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    <info>
        <title>Meta State Machine (MSM)</title>
        <author>
            <personname>Christophe Henry</personname>
            <email>christophe.j.henry@googlemail.com</email>
        </author>
        <copyright>
            <year>2008-2010</year>
            <holder>
                <phrase> Distributed under the Boost Software License, Version 1.0. (See
                    accompanying file LICENSE_1_0.txt or copy at <link
                        xlink:href="http://www.boost.org/LICENSE_1_0.txt"
                        >http://www.boost.org/LICENSE_1_0.txt</link> ) </phrase>
            </holder>
        </copyright>
    </info>
    <preface>
        <title>Preface</title>
        <para>MSM is a library allowing you to easily and quickly define state machines of very high
            performance. From this point, two main questions usually quickly arise, so please allow
            me to try answering them upfront.</para>
        <para>
            <itemizedlist>
                <listitem>
                    <para>When do I need a state machine?</para>
                    <para>More often that you think. Very often, one defined a state machine
                        informally without even noticing it. For example, one declares inside a
                        class some boolean attribute, say to remember that a task has been
                        completed. Later the boolean actually needs a third value, so it becomes an
                        int. A few weeks, a second attribute is needed. Then a third. Soon, you find
                        yourself writing:</para>
                    <para><code>void incoming_data(data)</code></para>
                    <para><code>{</code></para>
                    <para><code> if (data == packet_3 &amp;&amp; flag1 == work_done &amp;&amp; flag2
                            > step3)...</code></para>
                    <para><code>}</code></para>
                    <para>This starts to look like event processing (contained inside data) if some
                        stage of the object life has been achieved (but is ugly).</para>
                    <para>This could be a protocol definition and it is a common use case for state
                        machines. Another common one is a user interface. The stage of the user's
                        interaction defines if some button is active, a functionality is available,
                        etc.</para>
                    <para>But there are many more use cases if you start looking. Actually, a whole
                        model-driven development method, Executable UML
                        (http://en.wikipedia.org/wiki/Executable_UML) specifies its complete dynamic
                        behavior using state machines. Class diagram, state machine diagrams, and an
                        action language are all you absolutely need in the Executable UML
                        world.</para>
                </listitem>
                <listitem>
                    <para>Another state machine library? What for?</para>
                    <para>True, there are many state machine libraries. This should already be an
                        indication that if you're not using any of them, you might be missing
                        something. Why should you use this one? Unfortunately, when looking for a
                        good state machine library, you usually pretty fast hit one or several of
                        the following snags:<itemizedlist>
                            <listitem>
                                <para>speed: "state machines are slow" is usually the first
                                    criticism you might hear. While it is often an excuse not to use
                                    any and instead resort to dirty, hand-written implementations (I
                                    mean, no, yours are not dirty of course, I'm talking about other
                                    developers). MSM removes this often feeble excuse because it is
                                    blazingly fast. Most hand-written implementations will be beaten
                                    by MSM.</para>
                            </listitem>
                            <listitem>
                                <para>ease of use: good argument. If you used another library, you
                                    are probably right. Many state machine definitions will look
                                    similar to:</para>
                                <para><code>state s1 = new State; // a state</code></para>
                                <para><code>state s2 = new State; // another state</code></para>
                                <para><code>event e = new Event; // event</code></para>
                                <para><code>s1->addTransition(e,s2); // transition s1 ->
                                    s2</code></para>
                                <para>The more transitions you have, the less readable it is. A long
                                    time ago, there was not so much Java yet, and many electronic
                                    systems were built with a state machine defined by a simple
                                    transition table. You could easily see the whole structure and
                                    immediately see if you forgot some transitions. Thanks to our
                                    new OO techniques, this ease of use was gone. MSM gives you back
                                    the transition table and reduces the noise to the
                                    minimum.</para>
                            </listitem>
                            <listitem>
                                <para>expressiveness: MSM offers several front-ends and constantly
                                    tries to improve state machine definition techniques. For
                                    example, you can define a transition with eUML (one of MSM's
                                    front-ends) as:</para>
                                <para><code>state1 == state2 + event [condition] /
                                    action</code></para>
                                <para>This is not simply syntactic sugar. Such a formalized,
                                    readable structure allows easy communication with domain experts
                                    of a software to be constructed. Having domain experts
                                    understand your code will greatly reduce the number of
                                    bugs.</para>
                            </listitem>
                            <listitem>
                                <para>model-driven-development: a common difficulty of a
                                    model-driven development is the complexity of making a
                                    round-trip (generating code from model and then model from
                                    code). This is due to the fact that if a state machine structure
                                    is hard for you to read, chances are that your parsing tool will
                                    also have a hard time. MSM's syntax will hopefully help tool
                                    writers.</para>
                            </listitem>
                            <listitem>
                                <para>features: most developers use only 20% of the richly defined
                                    UML standard. Unfortunately, these are never the same 20% for
                                    all. And so, very likely, one will need something from the
                                    standard which is not implemented. MSM offers a very large part
                                    of the standard, with more on the way.</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>Let us not wait any longer, I hope you will enjoy MSM and have fun with
                        it!</para>
                </listitem>
            </itemizedlist>
        </para>
    </preface>
    <part>
        <title>User' guide</title>
        <chapter>
            <title>Founding idea</title>
            <para>Let's start with an example taken from the C++ Template Metaprogramming
                book:</para>
            <para>
                <code>class player : public state_machine&lt;player></code></para>
            <para><code>{ </code></para>
            <para><code>// The list of FSM states enum states { Empty, Open, Stopped, Playing,
                    Paused , initial_state = Empty }; </code></para>
            <para><code>// transition actions void start_playback(play const&amp;) { std::cout
                    &lt;&lt; "player::start_playback\n"; } </code></para>
            <para><code>void open_drawer(open_close const&amp;) { std::cout &lt;&lt;
                    "player::open_drawer\n"; } </code></para>
            <para><code>void close_drawer(open_close const&amp;) { std::cout &lt;&lt;
                    "player::close_drawer\n"; } </code></para>
            <para><code>void store_cd_info(cd_detected const&amp;) { std::cout &lt;&lt;
                    "player::store_cd_info\n"; } </code></para>
            <para><code>void stop_playback(stop const&amp;) { std::cout &lt;&lt;
                    "player::stop_playback\n"; } </code></para>
            <para><code>void pause_playback(pause const&amp;) { std::cout &lt;&lt;
                    "player::pause_playback\n"; } </code></para>
            <para><code>void resume_playback(play const&amp;) { std::cout &lt;&lt;
                    "player::resume_playback\n"; } </code></para>
            <para><code>void stop_and_open(open_close const&amp;) { std::cout &lt;&lt;
                    "player::stop_and_open\n"; } </code></para>
            <para><code>friend class state_machine&lt;player>; </code></para>
            <para><code>typedef player p; // makes transition table cleaner </code></para>
            <para><code>// Transition table </code></para>
            <para><code>struct transition_table : mpl::vector11&lt; </code></para>
            <para><code>row &lt; Stopped , play , Playing , &amp;p::start_playback >, </code></para>
            <para><code>row &lt; Stopped , open_close , Open , &amp;p::open_drawer >, </code></para>
            <para><code>row &lt; Open , open_close , Empty , &amp;p::close_drawer >, </code></para>
            <para><code>row &lt; Empty , open_close , Open , &amp;p::open_drawer >, </code></para>
            <para><code>row &lt; Empty , cd_detected , Stopped , &amp;p::store_cd_info >,
                </code></para>
            <para><code>row &lt; Playing , stop , Stopped , &amp;p::stop_playback >, </code></para>
            <para><code>row &lt; Playing , pause , Paused , &amp;p::pause_playback >, </code></para>
            <para><code>row &lt; Playing , open_close , Open , &amp;p::stop_and_open >,
                </code></para>
            <para><code>row &lt; Paused , play , Playing , &amp;p::resume_playback >, </code></para>
            <para><code>row &lt; Paused , stop , Stopped , &amp;p::stop_playback >, </code></para>
            <para><code>row &lt; Paused , open_close , Open , &amp;p::stop_and_open > </code></para>
            <para><code>> {}; </code></para>
            <para><code>// Replaces the default no-transition response. </code></para>
            <para><code>template &lt;class Event> int no_transition(int state, Event const&amp; e) {
                    std::cout &lt;&lt; "no transition from state " &lt;&lt; state &lt;&lt; " on
                    event " &lt;&lt; typeid(e).name() &lt;&lt; std::endl; return state; } };</code>
            </para>
            <para><code>void test() { player p; p.process_event(open_close());...}</code></para>
            <para>This example is the foundation for the idea driving MSM: a descriptive and
                expressive language based on a transition table with as little syntactic noise as
                possible, all this while offering as many features from the UML 2.0 standard as
                possible. MSM also offers several expressive state machine definition syntaxes with
                different trade-offs.</para>
        </chapter>
        <chapter>
            <title>UML Short Guide</title>
            <sect1>
                <title>What are state machines?</title>
                <para>State machines are the description of a thing's lifeline. They describe the
                    different stages of the lifeline, the events influencing it, and what it does
                    when a particular event is detected at a particular stage. They offer the
                    complete specification of the dynamic behavior of the thing.</para>
            </sect1>
            <sect1>
                <title>Concepts</title>
                <para>Thinking in terms of state machines is a bit surprising at first, so let us
                    have a quick glance at the concepts.</para>
                <sect2>
                    <title>State machine, state, transition, event </title>
                    <para>A state machine is a concrete model describing the behavior of a system.
                        It is composed of a finite number of states and transitions.</para>
                    <para>
                        <inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/sm.gif"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>A simple state has no sub states. It can have data, entry and exit
                        behaviors and deferred events. One can provide entry and exit behaviors
                        (also called actions) to states (or state machines), which are executed
                        whenever a state is entered or left, no matter how. A state can also have
                        internal transitions which cause no entry or exit behavior to be called. A
                        state can mark events as deferred. This means the event cannot be processed
                        if this state is active, but it must be retained. Next time a state not
                        deferring this event is active, the event will be processed, as if it had
                        just been fired. </para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/state.gif"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>A transition is the switching between active states, triggered by an
                        event. Actions and guard conditions can be attached to the transition. The
                        action executes when the transition fires, the guard is a Boolean operation
                        executed first and which can prevent the transition from firing by returning
                        false.</para>
                    <para>
                        <inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/transition.jpg"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>An initial state marks the first active state of a state machine. It has
                        no real existence and neither has the transition originating from it.</para>
                    <para>
                        <inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/init_state.gif"/>
                            </imageobject>
                        </inlinemediaobject></para>
                </sect2>
                <sect2>
                    <title>Submachines, orthogonal regions, pseudostates </title>
                    <para>A composite state is a state containing a region or decomposed in two or
                        more regions. A composite state contains its own set of states and regions. </para>
                    <para>A submachine is a state machine inserted as a state in another state
                        machine. The same submachine can be inserted more than once. </para>
                    <para>Orthogonal regions are parts of a composite state or submachine, each
                        having its own set of mutually exclusive set of states and transitions. </para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/regions.gif" width="60%" scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>UML also defines a number of pseudo states, which are considered important
                        concepts to model, but not enough to make them first-class citizens. The
                        terminate pseudo state terminates the execution of a state machine (MSM
                        handles this slightly differently. The state machine is not destroyed but no
                        further event processing occurs.). </para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/terminate.gif"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>An exit point pseudo state exits a composite state or a submachine and
                        forces termination of execution in all contained regions.</para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/exit.gif" width="60%" scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>An entry point pseudo state allows a kind of controlled entry inside a
                        composite. Precisely, it connects a transition outside the composite to a
                        transition inside the composite. An important point is that this mechanism
                        only allows a single region to be entered. In the above diagram, in region1,
                        the initial state would become active. </para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/entry_point.gif"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>There are also two more ways to enter a submachine (apart the obvious and
                        more common case of a transition terminating on the submachine as shown in
                        the region case). An explicit entry means that an inside state is the target
                        of a transition. Unlike with direct entry, no tentative encapsulation is
                        made, and only one transition is executed. An explicit exit is a transition
                        from an inner state to a state outside the submachine (not supported by
                        MSM). I would not recommend using explicit entry or exit. </para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/explicit.gif"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>The last entry possibility is using fork. A fork is an explicit entry into
                        one or more regions. Other regions are again activated using their initial
                        state. </para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/fork.gif" width="70%" scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                </sect2>
                <sect2>
                    <title>
                        <command xml:id="uml-history"/>History </title>
                    <para>UML defines two kinds of history, shallow history and deep history.
                        Shallow history is a pseudo state representing the most recent substate of a
                        submachine. A submachine can have at most one shallow history. A transition
                        with a history pseudo state as target is equivalent to a transition with the
                        most recent substate as target. And very importantly, only one transition
                        may originate from the history. Deep history is a shallow history
                        recursively reactivating the substates of the most recent substate. It is
                        represented like the shallow history with a star (H* inside a
                        circle).</para>
                    <para>
                        <inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/history.gif" width="60%" scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>History is not a completely satisfying concept. First of all, there can be
                        just one history pseudo state and only one transition may originate from it.
                        So they do not mix well with orthogonal regions as only one region can be
                        “remembered”. Deep history is even worse and looks like a last-minute
                        addition. History has to be activated by a transition and only one
                        transition originates from it, so how to model the transition originating
                        from the deep history pseudo state and pointing to the most recent substate
                        of the substate? As a bonus, it is also inflexible and does not accept new
                        types of histories. Let's face it, history sounds great and is useful in
                        theory, but the UML version is not quite making the cut. And therefore, MSM
                        provides a different version of this useful concept. </para>
                </sect2>
                <sect2>
                    <title><command xml:id="uml-anonymous"/>Completion transitions / anonymous
                        transitions</title>
                    <para>Completion events (or transitions), also called anonymous transitions, are
                        defined as transitions having no defined event triggering them. This means
                        that such transitions will immediately fire when a state being the source of
                        an anonymous transition becomes active, provided that a guard allows it.
                        They are useful in modeling algorithms as an activity diagram would normally
                        do. In the real-time world, they have the advantage of making it easier to
                        estimate how long a periodically executed action will last. For example,
                        consider the following diagram. </para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/completion.gif"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>The designer now knows at any time that he will need a maximum of 4
                        transitions. Being able to estimate how long a transition takes, he can
                        estimate how much of a time frame he will need to require (real-time tasks
                        are often executed at regular intervals). If he can also estimate the
                        duration of actions, he can even use graph algorithms to better estimate his
                        timing requirements. </para>
                </sect2>
                <sect2>
                    <title><command xml:id="UML-internal-transition"/> Internal transitions </title>
                    <para>Internal transitions are transitions executing in the scope of the active
                        state, being a simple state or a submachine. One can see them as a
                        self-transition of this state, without an entry or exit action
                        called.</para>
                </sect2>
                <sect2>
                    <title>
                        <command xml:id="transition-conflict"/>Conflicting transitions </title>
                    <para>If, for a given event, several transitions are enabled, they are said to
                        be in conflict. There are two kinds of conflicts: <itemizedlist>
                            <listitem>
                                <para>For a given source state, several transitions are defined,
                                    triggered by the same event. Normally, the guard condition in
                                    each transition defines which one is fired.</para>
                            </listitem>
                            <listitem>
                                <para>The source state is a submachine or simple state and the
                                    conflict is between a transition internal to this state and a
                                    transition triggered by the same event and having as target
                                    another state.</para>
                            </listitem>
                        </itemizedlist>The first one is simple; one only needs to define two or more
                        rows in the transition table, with the same source and trigger, with a
                        different guard condition. Beware, however, that the UML standard wants
                        these conditions to be not overlapping. If they do, the standard says
                        nothing except that this is incorrect, so the implementer is free to
                        implement it the way he sees fit. In the case of MSM, the transition
                        appearing last in the transition table gets selected first, if it returns
                        false (meaning disabled), the library tries with the previous one, and so
                        on.</para>
                    <para>
                        <inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/conflict1.gif"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>In the second case, UML defines that the most inner transition gets
                        selected first, which makes sense, otherwise no exit point pseudo state
                        would be possible (the inner transition brings us to the exit point, from
                        where the containing state machine can take over). </para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/conflict2.gif" width="60%" scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>MSM handles both cases itself, so the designer needs only concentrate on
                        its state machine and the UML subtleties (not overlapping conditions), not
                        on implementing this behavior himself. </para>
                </sect2>
            </sect1>
            <sect1>
                <title>State machine glossary</title>
                <para>
                    <itemizedlist>
                        <listitem>
                            <para>state machine: the life cycle of a thing. It is made of states,
                                regions, transitions and processes incoming events.</para>
                        </listitem>
                        <listitem>
                            <para>state: a stage in the life cycle of a state machine. A state (like
                                a submachine) can have an entry and exit behaviors.</para>
                        </listitem>
                        <listitem>
                            <para>event: an incident provoking (or not) a reaction of the state
                                machine</para>
                        </listitem>
                        <listitem>
                            <para>transition: a specification of how a state machine reacts to an
                                event. It specifies a source state, the event triggering the
                                transition, the target state (which will become the newly active
                                state if the transition is triggered), guard and actions.</para>
                        </listitem>
                        <listitem>
                            <para>action: an operation executed during the triggering of the
                                transition.</para>
                        </listitem>
                        <listitem>
                            <para>guard: a boolean operation being able to prevent the triggering of
                                a transition which would otherwise fire.</para>
                        </listitem>
                        <listitem>
                            <para>transition table: representation of a state machine. A state
                                machine diagram is a graphical, but incomplete representation of the
                                same model. A transition table, on the other hand, is a complete
                                representation.</para>
                        </listitem>
                        <listitem>
                            <para>initial state: The state in which the state machine starts. Having
                                several orthogonal regions means having as many initial
                                states.</para>
                        </listitem>
                        <listitem>
                            <para>submachine: A submachine is a state machine inserted as a state in
                                another state machine and can be found several times in a same state
                                machine.</para>
                        </listitem>
                        <listitem>
                            <para>orthogonal regions: (logical) parallel flow of execution of a
                                state machine. Every region of a state machine gets a chance to
                                process an incoming event.</para>
                        </listitem>
                        <listitem>
                            <para>terminate pseudo-state: when this state becomes active, it
                                terminates the execution of the whole state machine. MSM does not
                                destroy the state machine as required by the UML standard, however,
                                which lets you keep all the state machine's data.</para>
                        </listitem>
                        <listitem>
                            <para>entry/exit pseudo state: defined for submachines and are defined
                                as a connection between a transition outside of the submachine and a
                                transition inside the submachine. It is a way to enter or leave a
                                submachine through a predefined point.</para>
                        </listitem>
                        <listitem>
                            <para>fork: a fork allows explicit entry into several orthogonal regions
                                of a submachine.</para>
                        </listitem>
                        <listitem>
                            <para>history: a history is a way to remember the active state of a
                                submachine so that the submachine can proceed in its last active
                                state next time it becomes active.</para>
                        </listitem>
                        <listitem>
                            <para>completion events (also called completion/anonymous transitions):
                                when a transition has no named event triggering it, it automatically
                                fires when the source state is active, unless a guard forbids
                                it.</para>
                        </listitem>
                        <listitem>
                            <para>transition conflict: a conflict is present if for a given source
                                state and incoming event, several transitions are possible. UML
                                specifies that guard conditions have to solve the conflict.</para>
                        </listitem>
                        <listitem>
                            <para>internal transitions: transition from a state to itself without
                                having exit and entry actions being called.</para>
                        </listitem>
                    </itemizedlist>
                </para>
            </sect1>
        </chapter>
        <chapter>
            <title>Tutorial</title>
            <sect1>
                <title>Design</title>
                <para>MSM is divided between front–ends and back-ends. At the moment, there is just
                    one back-end. On the front-end side, you will find three of them which are as
                    many state machine description languages, with many more possible. For potential
                    language writers, this document contains a <link
                        xlink:href="#internals-front-back-interface">description of the interface
                        between front-end and back-end</link>.</para>
                <para>The first front-end is an adaptation of the example provided in the <link
                        xlink:href="http://boostpro.com/mplbook">MPL book</link> with actions
                    defined as pointers to state or state machine methods. The second one is based
                    on functors. The third, eUML (embedded UML) is an experimental language based on
                    Boost.Proto and Boost.Typeof and hiding most of the metaprogramming to increase
                    readability. Both eUML and the functor front-end also offer a functional library
                    (a bit like Boost.Phoenix) for use as action language (UML defining
                    none).</para>
            </sect1>
            <sect1>
                <title><command xml:id="basic-front-end"/>Basic front-end</title>
                <para>This is the historical front-end, inherited from the MPL book. It provides a
                    transition table made of rows of different names and functionality. Actions and
                    guards are defined as methods and referenced through a pointer in the
                    transition. This front-end provides a simple interface making easy state
                    machines easy to define, but more complex state machines a bit harder.</para>
                <sect2>
                    <title>A simple example</title>
                    <para>Let us have a look at a state machine diagram of the founding
                        example:</para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/SimpleTutorial.jpg" width="60%"
                                    scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>We are now going to build it with MSM's basic front-end. An <link
                            xlink:href="examples/SimpleTutorial.cpp">implementation</link> is also
                        provided.</para>
                </sect2>
                <sect2>
                    <title>Transition table</title>
                    <para>As previously stated, MSM is based on the transition table, so let us
                        define one:</para>
                    <programlisting> 
struct transition_table : mpl::vector&lt;
//    Start     Event        Target      Action                      Guard 
//   +---------+------------+-----------+---------------------------+----------------------------+ 
a_row&lt; Stopped , play       ,  Playing  , &amp;player_::start_playback                               >,
a_row&lt; Stopped , open_close ,  Open     , &amp;player_::open_drawer                                  >,
 _row&lt; Stopped , stop       ,  Stopped                                                           >,
//   +---------+------------+-----------+---------------------------+----------------------------+ 
a_row&lt; Open    , open_close ,  Empty    , &amp;player_::close_drawer                                 >,
//   +---------+------------+-----------+---------------------------+----------------------------+ 
a_row&lt; Empty   , open_close ,  Open     , &amp;player_::open_drawer                                  >,
  row&lt; Empty   , cd_detected,  Stopped  , &amp;player_::store_cd_info   , &amp;player_::good_disk_format >,
  row&lt; Empty   , cd_detected,  Playing  , &amp;player_::store_cd_info   , &amp;player_::auto_start       >,
//   +---------+------------+-----------+---------------------------+----------------------------+ 
a_row&lt; Playing , stop       ,  Stopped  , &amp;player_::stop_playback                                >,
a_row&lt; Playing , pause      ,  Paused   , &amp;player_::pause_playback                               >,
a_row&lt; Playing , open_close ,  Open     , &amp;player_::stop_and_open                                >,
//   +---------+------------+-----------+---------------------------+----------------------------+ 
a_row&lt; Paused  , end_pause  ,  Playing  , &amp;player_::resume_playback                              >,
a_row&lt; Paused  , stop       ,  Stopped  , &amp;player_::stop_playback                                >,
a_row&lt; Paused  , open_close ,  Open     , &amp;player_::stop_and_open                                >
//   +---------+------------+-----------+---------------------------+----------------------------+ 
> {};
                        </programlisting>
                    <para>You will notice that this is almost exactly our founding example. The only
                        change in the transition table is the different types of transitions (rows).
                        The founding example forces one to define an action method and offers no
                        guards. You have 4 basic row types:<itemizedlist>
                            <listitem>
                                <para><code>row</code> takes 5 arguments: start state, event, target
                                    state, action and guard.</para>
                            </listitem>
                            <listitem>
                                <para><code>a_row</code> (“a” for action) allows defining only the
                                    action and omit the guard condition.</para>
                            </listitem>
                            <listitem>
                                <para><code>g_row</code> (“g” for guard) allows omitting the action
                                    behavior and defining only the guard.</para>
                            </listitem>
                            <listitem>
                                <para><code>_row</code> allows omitting action and guard.</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>The signature for an action methods is void method_name (event
                        const&amp;), for example:</para>
                    <programlisting>void stop_playback(stop const&amp;)</programlisting>
                    <para>Action methods return nothing and take the argument as const reference. Of
                        course nothing forbids you from using the same action for several
                        events:</para>
                    <programlisting>template &lt;class Event> void stop_playback(Eventconst&amp;)</programlisting>
                    <para>Guards have as only difference the return value, which is a
                        boolean:</para>
                    <programlisting>bool good_disk_format(cd_detected const&amp; evt)</programlisting>
                    <para>The transition table is actually a MPL vector (or list), which brings the
                        limitation that the default maximum size of the table is 20. If you need
                        more transitions, overriding this default behavior is necessary, so you need
                        to add before any header:</para>
                    <programlisting>#define BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS
#define BOOST_MPL_LIMIT_VECTOR_SIZE 30 //or whatever you need                       
#define BOOST_MPL_LIMIT_MAP_SIZE 30 //or whatever you need                   </programlisting>
                    <para>The other limitation is that the MPL types are defined only up to 50
                        entries. For the moment, the only solution to achieve more is to add headers
                        to the MPL (luckily, this is not very complicated).</para>
                </sect2>
                <sect2>
                    <title>Defining states with entry/exit actions</title>
                    <para>While states were enums in the MPL book, they now are classes, which
                        allows them to hold data, provide entry, exit behaviors and be reusable (as
                        they do not know anything about the containing state machine). To define a
                        state, inherit from the desired state type. You will mainly use simple
                        states:</para>
                    <para>struct Empty : public msm::front::state&lt;> {};</para>
                    <para>They can optionally provide entry and exit behaviors:</para>
                    <programlisting language="C++">
struct Empty : public msm::front::state&lt;> 
{
    template &lt;class Event, class Fsm> 
    void on_entry(Event const&amp;, Fsm&amp; ) 
    {std::cout &lt;&lt;"entering: Empty" &lt;&lt; std::endl;} 
    template &lt;class Event, class Fsm> 
    void on_exit(Event const&amp;, Fsm&amp; ) 
    {std::cout &lt;&lt;"leaving: Empty" &lt;&lt; std::endl;} 
};
                    </programlisting>
                    <para>Notice how the entry and exit behaviors are templatized on the event and
                        state machine. Being generic facilitates reuse. There are more state types
                        (terminate, interrupt, pseudo states, etc.) corresponding to the UML
                        standard state types. These will be described in details in the next
                        sections.</para>
                </sect2>
                <sect2>
                    <title>What do you actually do inside actions / guards?</title>
                    <para>State machines define a structure and important parts of the complete
                        behavior, but not all. For example if you need to send a rocket to Alpha
                        Centauri, you can have a transition to a state "SendRocketToAlphaCentauri"
                        but no code actually sending the rocket. This is where you need actions. So
                        a simple action could be:</para>
                    <programlisting>template &lt;class Fire> void send_rocket(Fire const&amp;)
{
  fire_rocket();
}</programlisting>
                <para>Ok, this was simple. Now, we might want to give a direction. Let us suppose
                        this information is externally given when needed, it makes sense do use the
                        event for this:</para>
                <programlisting>// Event
struct Fire {Direction direction;};
template &lt;class Fire> void send_rocket(Fire const&amp; evt)
{
  fire_rocket(evt.direction);
}</programlisting>
                    <para>We might want to calculate the direction based not only on external data
                        but also on data accumulated during previous work. In this case, you might
                        want to have this data in the state machine itself. As transition actions
                        are members of the front-end, you can directly access the data:</para>
                    <programlisting>// Event
struct Fire {Direction direction;};
//front-end definition, see down
struct launcher_ : public msm::front::state_machine_def&lt;launcher_>{
Data current_calculation; 
template &lt;class Fire> void send_rocket(Fire const&amp; evt)
{
  fire_rocket(evt.direction, current_calculation);
}
...
};</programlisting>                    
                    <para>Entry and exit actions represent a behavior common to a state, no matter
                        through which transition it is entered or left. States being reusable, it
                        might make sense to locate your data there instead of in the state machine,
                        to maximize reuse and make code more readable. Entry and exit actions have
                        access to the state data (being state members) but also to the event and
                        state machine, like transition actions. This happens through the Event and
                        Fsm template parameters:</para>
                    <programlisting>struct Launching : public msm::front::state&lt;> 
{
    template &lt;class Event, class Fsm> 
    void on_entry(Event const&amp; evt, Fsm&amp; fsm) 
    {
       fire_rocket(evt.direction, fsm.current_calculation);
    } 
};</programlisting>
                    <para>Exit actions are also ideal for clanup when the state becomes
                        inactive.</para>
                    <para>Another possible use of the entry action is to pass data to substates /
                        submachines. Launching is a substate containing  a <code>data</code> attribute:</para>
                    <programlisting>struct launcher_ : public msm::front::state_machine_def&lt;launcher_>{
Data current_calculation;
// state machines also have entry/exit actions 
template &lt;class Event, class Fsm> 
void on_entry(Event const&amp; evt, Fsm&amp; fsm) 
{
   launcher_::Launching&amp; s = fsm.get_state&lt;launcher_::Launching&amp;>();
   s.data = fsm.current_calculation;
} 
...
};</programlisting>
                    <para>The <command xlink:href="#backend-fsm-constructor-args">set_states</command> back-end method allows you to replace a complete
                        state.</para>
                    <para>The <command xlink:href="#functor-front-end-actions">functor</command> front-end and eUML offer more capabilities.</para>
                    <para>However, this basic front-end also has special capabilities using the row2
                        / irow2 transitions.<command xlink:href="#basic-row2">_row2, a_row2, row2,
                            g_row2, a_irow2, irow2, g_irow2</command> let you call an action located
                        in any state of the current fsm or in the front-end itself, thus letting you
                        place useful data anywhere you see fit.</para>
                    <para>It is sometimes desirable to generate new events for the state machine
                        inside actions. Since the process_event method belongs to the back end, you
                        first need to gain a reference to it. The back end derives from the front
                        end, so one way of doing this is to use a cast:</para>
                    <programlisting>struct launcher_ : public msm::front::state_machine_def&lt;launcher_>{
template &lt;class Fire> void send_rocket(Fire const&amp; evt)
{
  fire_rocket();
  msm::back::state_machine&lt;launcher_> &amp;fsm = static_cast&lt;msm::back::state_machine&lt;launcher_> &amp;>(*this);
  fsm.process_event(rocket_launched());
}
...
};</programlisting>
                    <para>The same can be implemented inside entry/exit actions. Admittedly, this is
                        a bit awkward. A more natural mechanism is available using the <command
                            xlink:href="#functor-front-end-actions">functor</command>
                        front-end.</para>
                </sect2>
                <sect2>
                    <title>Defining a simple state machine</title>
                    <para>Declaring a state machine is straightforward and is done with a high
                        signal / noise ratio. In our player example, we declare the state machine
                        as:</para>
                    <programlisting>struct player_ : public msm::front::state_machine_def&lt;player_>{
                            /* see below */}</programlisting>
                    <para>This declares a state machine using the basic front-end. We now declare
                        inside the state machine structure the initial state:</para>
                    <para>
                        <programlisting>typedef Empty initial_state;</programlisting>
                    </para>
                    <para>And that is about all of what is absolutely needed. In the example, the
                        states are declared inside the state machine for readability but this is not
                        a requirements, states can be declared wherever you like.</para>
                    <para>All what is left to do is to pick a back-end (which is quite simple as
                        there is only one at the moment):</para>
                    <para>
                        <programlisting>typedef msm::back::state_machine&lt;player_> player;</programlisting>
                    </para>
                    <para>You now have a ready-to-use state machine with entry/exit actions, guards,
                        transition actions, a message queue so that processing an event can generate
                        another event. The state machine also adapted itself to your need and
                        removed almost all features we didn't use in this simple example. Note that
                        this is not per default the fastest possible state machine. See the section
                        "getting more speed" to know how to get the maximum speed. In a nutshell,
                        MSM cannot know about your usage of some features so you will have to
                        explicitly tell it.</para>
                    <para>State objects are built automatically with the state machine. They will
                        exist until state machine destruction. MSM is using Boost.Fusion behind the
                        hood. This unfortunately means that if you define more than 10 states, you
                        will need to extend the default:</para>
                    <para>
                        <programlisting>#define FUSION_MAX_VECTOR_SIZE 20 // or whatever you need
                        </programlisting>
                    </para>
                    <para>When an unexpected event is fired, the <code>no_transition(event, state
                            machine, state id)</code> method of the state machine is called . By
                        default, this method simply asserts when called. It is possible to overwrite
                        the <code>no_transition</code> method to define a different handling:</para>
                    <para>
                        <programlisting>template &lt;class Fsm,class Event> 
void no_transition(Event const&amp; e, Fsm&amp; ,int state){...}</programlisting>
                    </para>
                    <para><emphasis role="underline">Note</emphasis>: you might have noticed that
                        the tutorial calls <code>start()</code> on the state machine just after
                        creation. The start method will initiate the state machine, meaning it will
                        activate the initial state, which means in turn that the initial state's
                        entry behavior will be called. The reason why we need this will be explained
                        in the <link xlink:href="#backend-start">back-end part</link>. After a call
                        to start, the state machine is ready to process events. The same way,
                        calling <code>stop()</code> will cause the last exit actions to be called.</para>
                </sect2>
                <sect2>
                    <title>Defining a submachine</title>
                    <para>We now want to extend our last state machine by making the Playing state a
                        state machine itself (a submachine).</para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/CompositeTutorial.jpg" width="60%"
                                    scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>Again, an <link xlink:href="examples/CompositeTutorial.cpp">example</link>
                        is also provided.</para>
                    <para>A submachine really is a state machine itself, so we declare Playing as
                        such, choosing a front-end and a back-end:</para>
                    <para>
                        <programlisting>struct Playing_ : public msm::front::state_machine_def&lt;Playing_>{...} 
typedef msm::back::state_machine&lt;Playing_> Playing;</programlisting>
                    </para>
                    <para>Like for any state machine, one also needs a transition table and an
                        initial state:</para>
                    <para>
                        <programlisting> 
struct transition_table : mpl::vector&lt;
//    Start    Event    Target    Action                      Guard 
//   +--------+---------+--------+---------------------------+------+ 
a_row&lt; Song1  , NextSong, Song2  , &amp;Playing_::start_next_song        >,
a_row&lt; Song2  , NextSong, Song1  , &amp;Playing_::start_prev_song        >,
a_row&lt; Song2  , NextSong, Song3  , &amp;Playing_::start_next_song        >,
a_row&lt; Song3  , NextSong, Song2  , &amp;Playing_::start_prev_song        >
//   +--------+---------+--------+---------------------------+------+ 
> {};
                        </programlisting>
                    </para>
                    <para>
                        <programlisting>typedef Song1 initial_state; </programlisting>
                    </para>
                    <para>This is about all you need to do. MSM will now automatically recognize
                        Playing as a submachine and all events handled by Playing (NextSong and
                        PreviousSong) will now be automatically forwarded to Playing whenever this
                        state is active. All other state machine features described later are also
                        available. You can even decide to use a state machine sometimes as
                        submachine or sometimes as an independent state machine.</para>
                </sect2>
                <sect2>
                    <title>Orthogonal regions, terminate state, event deferring</title>
                    <para>It is a very common problem in many state machines to have to handle
                        errors. It usually involves defining a transition from all the states to a
                        special error state. Translation: not fun. It is also not practical to find
                        from which state the error originated. The following diagram shows an
                        example of what clearly becomes not very readable:</para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/error_no_regions.jpg" width="60%"
                                    scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>This is neither very readable nor beautiful. And we do not even have any
                        action on the transitions yet to make it even less readable.</para>
                    <para>Luckily, UML provides a helpful concept, orthogonal regions. See them as
                        lightweight state machines running at the same time inside a common state
                        machine and having the capability to influence one another. The effect is
                        that you have several active states at any time. We can therefore keep our
                        state machine from the previous example and just define a new region made of
                        two states, AllOk and ErrorMode. AllOk is most of the time active. But the
                        error_found error event makes the second region move to the new active state
                        ErrorMode. This event does not interest the main region so it will simply be
                        ignored. "<code>no_transition</code>" will be called only if no region at
                        all handles the event. Also, as UML mandates, every region gets a chance of
                        handling the event, in the order as declared by the
                            <code>initial_state</code> type.</para>
                    <para>Adding an orthogonal region is easy, one only needs to declare more states
                        in the <code>initial_state</code> typedef. So, adding a new region with
                        AllOk as the region's initial state is:</para>
                    <para>
                        <programlisting>typedef mpl::vector&lt;Empty,AllOk> initial_state;</programlisting>
                    </para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/Orthogonal-deferred.jpg" width="60%"
                                    scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>Furthermore, when you detect an error, you usually do not want events to
                        be further processed. To achieve this, we use another UML feature, terminate
                        states. When any region moves to a terminate state, the state machine
                        “terminates” (the state machine and all its states stay alive) and all
                        events are ignored. This is of course not mandatory, one can use orthogonal
                        regions without terminate states. MSM also provides a small extension to
                        UML, interrupt states. If you declare ErrorMode as interrupt state instead
                        of terminate state, the state machine will not handle any event other than
                        the one which ends the interrupt. So it's like a terminate state, with the
                        difference that you are allowed to resume the state machine when a condition
                        (like handling of the original error) is met. </para>
                    <para><command xml:id="basic-defer"/>Last but not least, this example also shows
                        here the handling of event deferring. Let's say someone puts a disc and
                        immediately presses play. The event cannot be handled, yet you'd want it to
                        be handled at a later point and not force the user to press play again. The
                        solution is to define it as deferred in the Empty and Open states and get it
                        handled in the first state where the event is not to be deferred. It can
                        then be handled or rejected. In this example, when Stopped becomes active,
                        the event will be handled because only Empty and Open defer the
                        event.</para>
                    <para>UML defines event deferring as a state property. To accommodate this, MSM
                        lets you specify this in states by providing a <code>deferred_events</code>
                        type:</para>
                    <programlisting>struct Empty : public msm::front::state&lt;> 
{
   // if the play event is fired while in this state, defer it until a state
   // handles or rejects it
   typedef mpl::vector&lt;play> deferred_events;
...
};                 </programlisting>
                    <para>Please have a look at the <link
                            xlink:href="examples/Orthogonal-deferred.cpp">complete
                        example</link>.</para>
                    <para>While this is wanted by UML and is simple, it is not always practical
                        because one could wish to defer only in certain conditions. One could also
                        want to make this be part of a transition action with the added bonus of a
                        guard for more sophisticated behaviors. It would also be conform to the MSM
                        philosophy to get as much as possible in the transition table, where you
                        have the whole state machine structure. This is also possible but not
                        practical with this front-end so we will need to pick a different row from
                        the functor front-end. For a complete description of the <code>Row</code>
                        type, please have a look at the <command xlink:href="#functor-front-end"
                            >functor front-end.</command></para>
                    <para>First, as there is no state where MSM can automatically find out the usage
                        of this feature, we need to require deferred events capability explicitly,
                        by adding a type in the state machine definition:</para>
                    <programlisting>struct player_ : public msm::front::state_machine_def&lt;player_>
{ 
    typedef int activate_deferred_events;
...
};                   </programlisting>
                    <para>We can now defer an event in any transition of the transition table by
                        using as action the predefined <code>msm::front::Defer</code> functor, for
                        example:</para>
                    <para>
                        <programlisting>Row &lt; Empty , play , none , Defer , none ></programlisting>
                    </para>
                    <para>This is an internal transition row(see <command
                            xlink:href="#internal-transitions">internal transitions</command>) but
                        you can ignore this for the moment. It just means that we are not leaving
                        the Empty state. What matters is that we use Defer as action. This is
                        roughly equivalent to the previous syntax but has the advantage of giving
                        you all the information in the transition table with the added power of
                        transition behavior.</para>
                    <para>The second difference is that as we now have a transition defined, this
                        transition can play in the resolution of <command
                            xlink:href="#transition-conflict">transition conflicts</command>. For
                        example, we could model an "if (condition2) move to Playing else if
                        (condition1) defer play event":</para>
                    <para>
                        <programlisting>Row   &lt; Empty , play , none    , Defer , condition1   >,
g_row &lt; Empty , play , Playing , &amp;player_::condition2 ></programlisting>
                    </para>
                    <para>Please have a look at <link xlink:href="examples/Orthogonal-deferred2.cpp"
                            >this possible implementation</link>.</para>
                </sect2>
                <sect2>
                    <title>History</title>
                    <para>UML defines two types of history, Shallow History and Deep History. In the
                        previous examples, if the player was playing the second song and the user
                        pressed pause, leaving Playing, at the next press on the play button, the
                        Playing state would become active and the first song would play again. Soon
                        would the first client complaints follow. They'd of course demand, that if
                        the player was paused, then it should remember which song was playing. But
                        it the player was stopped, then it should restart from the first song. How
                        can it be done? Of course, you could add a bit of programming logic and
                        generate extra events to make the second song start if coming from Pause.
                        Something like: </para>
                    <para>
                        <programlisting>if (Event == end_pause) 
{ 
   for (int i=0;i&lt; song number;++i) {player.process_event(NextSong()); } 
} </programlisting>
                    </para>
                    <para>Not much to like in this example, isn't it? To solve this problem, you
                        define what is called a shallow or a deep history. A shallow history
                        reactivates the last active substate of a submachine when this submachine
                        becomes active again. The deep history does the same recursively, so if this
                        last active substate of the submachine was itself a submachine, its last
                        active substate would become active and this will continue recursively until
                        an active state is a normal state. For example, let us have a look at the
                        following UML diagram: </para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/HistoryTutorial.jpg" width="60%"
                                    scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>Notice that the main difference compared to previous diagrams is that the
                        initial state is gone and replaced by a History symbol (the H inside a
                        circle).</para>
                    <para>As explained in the <command xlink:href="#uml-history">small UML
                            tutorial</command>, History is a good concept with a not completely
                        satisfying specification. MSM kept the concept but not the specification and
                        goes another way by making this a policy and you can add your own history
                        types (the <link xlink:href="#history-interface">reference</link> explains
                        what needs to be done). Furthermore, History is a backend policy. This
                        allows you to reuse the same state machine definition with different history
                        policies in different contexts.</para>
                    <para>Concretely, your frontend stays unchanged:</para>
                    <para>
                        <programlisting>struct Playing_ : public msm::front::state_machine_def&lt;Playing_></programlisting>
                    </para>
                    <para>You then add the policy to the backend as second parameter:</para>
                    <para>
                        <programlisting>typedef msm::back::state_machine&lt;Playing_,
    msm::back::ShallowHistory&lt;mpl::vector&lt;end_pause> > > Playing;</programlisting>
                    </para>
                    <para>This states that a shallow history must be activated if the Playing state
                        machine gets activated by the end_pause event and only this one (or any
                        other event added to the mpl::vector). If the state machine was in the
                        Stopped state and the event play was generated, the history would not be
                        activated and the normal initial state would become active. By default,
                        history is disabled. For your convenience the library provides in addition
                        to ShallowHistory a non-UML standard AlwaysHistory policy (likely to be your
                        main choice) which always activates history, whatever event triggers the
                        submachine activation. Deep history is not available as a policy (but could
                        be added). The reason is that it would conflict with policies which
                        submachines could define. Of course, if for example, Song1 were a state
                        machine itself, it could use the ShallowHistory policy itself thus creating
                        Deep History for itself. An <link xlink:href="examples/History.cpp"
                            >example</link> is also provided.</para>
                </sect2>
                <sect2>
                    <title>Completion (anonymous) transitions</title>
                    <para><command xml:id="anonymous-transitions"/>The following diagram shows an
                        example making use of this feature:</para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/Anonymous.jpg" width="60%" scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>Anonymous transitions are transitions without a named event. This means
                        that the transition automatically fires when the predecessor state is
                        entered (to be exact, after the entry action). Otherwise it is a normal
                        transition with actions and guards. Why would you need something like that?
                        A possible case would be if a part of your state machine implements some
                        algorithm, where states are steps of the algorithm implementation. Then,
                        using several anonymous transitions with different guard conditions, you are
                        actually implementing some if/else statement. Another possible use would be
                        a real-time system called at regular intervals and always doing the same
                        thing, meaning implementing the same algorithm. The advantage is that once
                        you know how long a transition takes to execute on the system, by
                        calculating the longest path (the number of transitions from start to end),
                        you can pretty much know how long your algorithm will take in the worst
                        case, which in turns tells you how much of a time frame you are to request
                        from a scheduler. </para>
                    <para>If you are using Executable UML (a good book describing it is "Executable
                        UML, a foundation for Model-Driven Architecture"), you will notice that it
                        is common for a state machine to generate an event to itself only to force
                        leaving a state. Anonymous transitions free you from this constraint.</para>
                    <para>If you do not use this feature in a concrete state machine, MSM will
                        deactivate it and you will not pay for it. If you use it, there is however a
                        small performance penalty as MSM will try to fire a compound event (the
                        other UML name for anonymous transitions) after every taken transition. This
                        will therefore double the event processing cost, which is not as bad as it
                        sounds as MSM’s execution speed is very high anyway.</para>
                    <para>To define such a transition, use “none” as event in the transition table,
                        for example:</para>
                    <para>
                        <programlisting>row &lt; State3 , none , State4 , &amp;p::State3ToState4 , &amp;p::always_true ></programlisting>
                    </para>
                    <para><link xlink:href="examples/AnonymousTutorial.cpp">An implementation</link>
                        of the state machine diagram is also provided.</para>
                </sect2>
                <sect2>
                    <title><command xml:id="internal-transitions"/>Internal transitions</title>
                    <para>Internal transitions are transitions executing in the scope of the active
                        state, a simple state or a submachine. One can see them as a self-transition
                        of this state, without an entry or exit action called. This is useful when
                        all you want is to execute some code for a given event in a given
                        state.</para>
                    <para>Internal transitions are specified as having a higher priority than normal
                        transitions. While it makes sense for a submachine with exit points, it is
                        surprising for a simple state. MSM lets you define the transition priority
                        by setting the transition’s position inside the transition table (see
                            <command xlink:href="#run-to-completion">internals</command> ). The
                        difference between "normal" and internal transitions is that internal
                        transitions have no target state, therefore we need new row types. We had
                        a_row, g_row, _row and row, we now add a_irow, g_irow, _irow and irow which
                        are like normal transitions but define no target state. For, example an
                        internal transition with a guard condition could be:</para>
                    <para>
                        <programlisting>g_irow &lt; Empty /*state*/,cd_detected/*event*/,&amp;p::internal_guard/* guard */></programlisting>
                    </para>
                    <para>These new row types can be placed anywhere in the transition table so that
                        you can still have your state machine structure grouped together. The only
                        difference of behavior with the UML standard is the missing notion of higher
                        priority for internal transitions. Please have a look at <link
                            xlink:href="examples/SimpleTutorialInternal.cpp">the
                        example</link>.</para>
                    <para>It is also possible to do it the UML-conform way by declaring a transition
                        table called <code>internal transition_table</code> inside the state itself
                        and using internal row types. For example:</para>
                    <programlisting>struct Empty : public msm::front::state&lt;> 
{
    struct internal_transition_table : mpl::vector&lt;
           a_internal &lt; cd_detected , Empty, &amp;Empty::internal_action >
    > {};
};</programlisting>
                    <para>This declares an internal transition table called
                        internal_transition_table and reacting on the event cd_detected by calling
                        internal_action on Empty. Let us note a few points:<itemizedlist>
                            <listitem>
                                <para>internal tables are NOT called transition_table but
                                    internal_transition_table</para>
                            </listitem>
                            <listitem>
                                <para>they use different but similar row types: a_internal,
                                    g_internal, _internal and internal.</para>
                            </listitem>
                            <listitem>
                                <para>These types take as first template argument the triggering
                                    event and then the action and guard method. Note that the only
                                    real difference to classical rows is the extra argument before
                                    the function pointer. This is the type on which the function
                                    will be called.</para>
                            </listitem>
                            <listitem>
                                <para>This also allows you, if you wish, to use actions and guards
                                    from another state of the state machine or in the state machine
                                    itself.</para>
                            </listitem>
                            <listitem>
                                <para>submachines can have an internal transition table and a
                                    classical transition table.</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>The <link xlink:href="examples/TestInternal.cpp">following example</link>
                        makes use of an a_internal. It also uses functor-based internal transitions
                        which will be explained in <command
                            xlink:href="#functor-internal-transitions">the functor
                            front-end</command>, please ignore them for the moment. Also note that
                        the state-defined internal transitions, having the highest priority (as
                        mandated by the UML standard), are tried before those defined inside the
                        state machine transition table.</para>
                    <para>Which method should you use? It depends on what you need:<itemizedlist>
                            <listitem>
                                <para>the first version (using irow) is simpler and likely to
                                    compile faster. It also lets you choose the priority of your
                                    internal transition.</para>
                            </listitem>
                            <listitem>
                                <para>the second version is more logical from a UML perspective and
                                    lets you make states more useful and reusable. It also allows
                                    you to call actions and guards on any state of the state
                                    machine.</para>
                            </listitem>
                        </itemizedlist>
                        <command xml:id="internal-transitions-note"/><emphasis role="underline"
                                ><emphasis role="bold">Note</emphasis></emphasis>: There is an added
                        possibility coming from this feature. The
                            <code>internal_transition_table</code> transitions being added directly
                        inside the main state machine's transition table, it is possible, if it is
                        more to your state, to distribute your state machine definition a bit like
                        Boost.Statechart, leaving to the state machine itself the only task of
                        declaring the states it wants to use using the
                            <code>explicit_creation</code> type definition. While this is not the
                        author's favorite way, it is still possible. A simplified example using only
                        two states will show this possibility:<itemizedlist>
                            <listitem>
                                <para><link
                                        xlink:href="examples/distributed_table/DistributedTable.cpp"
                                        >state machine definition</link></para>
                            </listitem>
                            <listitem>
                                <para>Empty <link xlink:href="examples/distributed_table/Empty.hpp"
                                        >header</link> and <link
                                        xlink:href="examples/distributed_table/Empty.cpp"
                                    >cpp</link></para>
                            </listitem>
                            <listitem>
                                <para>Open <link xlink:href="examples/distributed_table/Open.hpp"
                                        >header</link> and <link
                                        xlink:href="examples/distributed_table/Open.cpp"
                                    >cpp</link></para>
                            </listitem>
                            <listitem>
                                <para><link xlink:href="examples/distributed_table/Events.hpp"
                                        >events definition</link></para>
                            </listitem>
                        </itemizedlist></para>
                    <para>There is an added bonus offered for submachines, which can have both the
                        standard transition_table and an internal_transition_table (which has a
                        higher priority). This makes it easier if you decide to make a full
                        submachine from a state. It is also slightly faster than the standard
                        alternative, adding orthogonal regions, because event dispatching will, if
                        accepted by the internal table, not continue to the subregions. This gives
                        you a O(1) dispatch instead of O(number of regions). While the example is
                        with eUML, the same is also possible with any front-end.</para>
                </sect2>
                <sect2>
                    <title><command xml:id="basic-row2"/>more row types</title>
                    <para>It is also possible to write transitions using actions and guards not just
                        from the state machine but also from its contained states. In this case, one
                        must specify not just a method pointer but also the object on which to call
                        it. This transition row is called, not very originally, <code>row2</code>.
                        They come, like normal transitions in four flavors: <code>a_row2, g_row2,
                            _row2 and row2</code>. For example, a transition calling an action from
                        the state Empty could be:</para>
                    <para>
                        <programlisting>a_row2&lt;Stopped,open_close,Open,Empty
      /*action source*/,&amp;Empty::open_drawer/*action*/></programlisting>
                    </para>
                    <para>The same capabilities are also available for internal transitions so that
                        we have: <code>a_irow2, g_irow2, _irow2 and row2</code>. For transitions
                        defined as part of the <code>internal_transition_table</code>, you can use
                        the <command xlink:href="#internal-transitions">a_internal, g_internal,
                            _internal, internal</command> row types from the previous
                        sections.</para>
                    <para>These row types allow us to distribute the state machine code among
                        states, making them reusable and more useful. Using transition tables inside
                        states also contributes to this possibility. An <link
                            xlink:href="examples/SimpleTutorial2.cpp">example</link> of these new
                        rows is also provided.</para>
                </sect2>
                <sect2>
                    <title>Explicit entry / entry and exit pseudo-state / fork</title>
                    <para>MSM (almost) fully supports these features, described in the <command
                            xlink:href="#uml-history">small UML tutorial</command>. Almost because
                        there are currently two limitations: <itemizedlist>
                            <listitem>
                                <para>it is only possible to explicitly enter a sub- state of the
                                    target but not a sub-sub state.</para>
                            </listitem>
                            <listitem>
                                <para>it is not possible to explicitly exit. Exit points must be
                                    used.</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>Let us see a concrete example:</para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/entrytutorial.jpg" width="60%"
                                    scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>We find in this diagram:<itemizedlist>
                            <listitem>
                                <para>A “normal” activation of SubFsm2, triggered by event1. In each
                                    region, the initial state is activated, i.e. SubState1 and
                                    SubState1b.</para>
                            </listitem>
                            <listitem>
                                <para>An explicit entry into SubFsm2::SubState2 for region “1” with
                                    event2 as trigger, meaning that in region “2” the initial state,
                                    SubState1b, activated.</para>
                            </listitem>
                            <listitem>
                                <para>A fork into regions “1” and “2” to the explicit entries
                                    SubState2 and SubState2b, triggered by event3. Both states
                                    become active so no region is default activated (if we had a
                                    third one, it would be).</para>
                            </listitem>
                            <listitem>
                                <para>A connection of two transitions through an entry pseudo state,
                                    SubFsm2::PseudoEntry1, triggered by event4 and triggering also
                                    the second transition on the same event (both transitions must
                                    be triggered by the same event). Region “2” is default-activated
                                    and SubState1b becomes active.</para>
                            </listitem>
                            <listitem>
                                <para>An exit from SubFsm2 using an exit pseudo-state, PseudoExit1,
                                    triggered by event5 and connecting two transitions using the
                                    same event. Again, the event is forwarded to the second
                                    transition and both regions are exited, as SubFsm2 becomes
                                    inactive. Note that if no transition is defined from
                                    PseudoExit1, an error (as defined in the UML standard) will be
                                    detected and no_transition called.</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>The example is also <link xlink:href="examples/DirectEntryTutorial.cpp"
                            >fully implemented</link>.</para>
                    <para>This sounds complicated but the syntax is simple.</para>
                    <sect3>
                        <title>Explicit entry</title>
                        <para>First, to define that a state is an explicit entry, you have to make
                            it a state and mark it as explicit, giving as template parameters the
                            region id (the region id starts with 0 and corresponds to the first
                            initial state of the initial_state type sequence).</para>
                        <para>
                            <programlisting>struct SubFsm2_ : public msm::front::state_machine_def&lt;SubFsm2_> 
{
   struct SubState2 : public msm::front::state&lt;> , 
                      public msm::front::explicit_entry&lt;0> 
   {...};
...
};</programlisting>
                        </para>
                        <para>And define the submachine as:</para>
                        <para>
                            <programlisting>typedef msm::back::state_machine&lt;SubFsm2_> SubFsm2;</programlisting>
                        </para>
                        <para>You can then use it as target in a transition with State1 as
                            source:</para>
                        <para>
                            <programlisting>_row &lt; State1, Event2, SubFsm2::direct&lt; SubFsm2_::SubState2> > //SubFsm2_::SubState2: complete name of SubState2 (defined within SubFsm2_)</programlisting>
                        </para>
                        <para>The syntax deserves some explanation. SubFsm2_ is a front end.
                            SubState2 is a nested state, therefore the SubFsm2_::SubState2 syntax.
                            The containing machine (containing State1 and SubFsm2) refers to the
                            backend instance (SubFsm2). SubFsm2::direct states that an explicit
                            entry is desired.</para>
                        <para><command xml:id="explicit-entry-no-region-id"/>Thanks to the <command xlink:href="#backend-compile-time-analysis"
                                >mpl_graph</command> library you can also omit to provide the region
                            index and let MSM find out for you. The are however two points to note:<itemizedlist>
                                <listitem>
                                    <para>MSM can only find out the region index if the explicit
                                        entry state is somehow connected to an initial state through
                                        a transition, no matter the direction.</para>
                                </listitem>
                                <listitem>
                                    <para>There is a compile-time cost for this feature.</para>
                                </listitem>
                            </itemizedlist></para>
                        <para><emphasis role="underline">Note (also valid for forks)</emphasis>: in
                            order to make compile time more bearable for the more standard cases,
                            and unlike initial states, explicit entry states which are also not
                            found in the transition table of the entered submachine (a rare case) do
                            NOT get automatically created. To explicitly create such states, you
                            need to add in the state machine containing the explicit states a simple
                            typedef giving a sequence of states to be explicitly created
                            like:</para>
                        <para>
                            <programlisting>typedef mpl::vector&lt;SubState2,SubState2b> explicit_creation;</programlisting>
                        </para>
                        <para><emphasis role="underline">Note (also valid for forks)</emphasis>: At
                            the moment, it is not possible to use a submachine as the target of an
                            explicit entry. Please use entry pseudo states for an almost identical
                            effect.</para>
                    </sect3>
                    <sect3>
                        <title>Fork</title>
                        <para>Need a fork instead of an explicit entry? As a fork is an explicit
                            entry into states of different regions, we do not change the state
                            definition compared to the explicit entry and specify as target a list
                            of explicit entry states:</para>
                        <para>
                            <programlisting>_row &lt; State1, Event3, 
        mpl::vector&lt;SubFsm2::direct&lt;SubFsm2_::SubState2>, 
        SubFsm2::direct &lt;SubFsm2_::SubState2b>
     ></programlisting>
                        </para>
                        <para>With SubState2 defined as before and SubState2b defined as being in
                            the second region (Caution: MSM does not check that the region is
                            correct):</para>
                        <para>
                            <programlisting>struct SubState2b : public msm::front::state&lt;> , 
                    public msm::front::explicit_entry&lt;1></programlisting>
                        </para>
                    </sect3>
                    <sect3>
                        <title>Entry pseudo states</title>
                        <para> To define an entry pseudo state, you need derive from the
                            corresponding class and give the region id:</para>
                        <para>
                            <programlisting>struct PseudoEntry1 : public msm::front::entry_pseudo_state&lt;0></programlisting>
                        </para>
                        <para>And add the corresponding transition in the top-level state machine's
                            transition table:</para>
                        <para>
                            <programlisting>_row &lt; State1, Event4, SubFsm2::entry_pt&lt;SubFsm2_::PseudoEntry1> ></programlisting>
                        </para>
                        <para>And another in the SubFsm2_ submachine definition (remember that UML
                            defines an entry point as a connection between two transitions), for
                            example this time with an action method:</para>
                        <para>
                            <programlisting>_row &lt; PseudoEntry1, Event4, SubState3,&amp;SubFsm2_::entry_action ></programlisting>
                        </para>
                    </sect3>
                    <sect3>
                        <title> Exit pseudo states </title>
                        <para>And finally, exit pseudo states are to be used almost the same way,
                            but defined differently: it takes as template argument the event to be
                            forwarded (no region id is necessary):</para>
                        <para>
                            <programlisting>struct PseudoExit1 : public exit_pseudo_state&lt;event6></programlisting>
                        </para>
                        <para>And you need, like for entry pseudo states, two transitions, one in
                            the submachine:</para>
                        <para>
                            <programlisting>_row &lt; SubState3, Event5, PseudoExit1 ></programlisting>
                        </para>
                        <para>And one in the containing state machine:</para>
                        <para>
                            <programlisting>_row &lt; SubFsm2::exit_pt&lt;SubFsm2_::PseudoExit1>, Event6,State2 ></programlisting>
                        </para>
                        <para><emphasis role="underline">Important note 1:</emphasis> UML defines
                            transiting to an entry pseudo state and having either no second
                            transition or one with a guard as an error but defines no error
                            handling. MSM will tolerate this behavior; the entry pseudo state will
                            simply be the newly active state.</para>
                        <para><emphasis role="underline">Important note 2</emphasis>: UML defines
                            transiting to an exit pseudo state and having no second transition as an
                            error, and also defines no error handling. Therefore, it was decided to
                            implement exit pseudo state as terminate states and the containing
                            composite not properly exited will stay terminated as it was technically
                            “exited”.</para>
                        <para><emphasis role="underline">Important note 3:</emphasis> UML states
                            that for the exit point, the same event must be used in both
                            transitions. MSM relaxes this rule and only wants the event on the
                            inside transition to be convertible to the one of the outside
                            transition. In our case, event6 is convertible from event5. Notice that
                            the forwarded event must be named in the exit point definition. For
                            example, we could define event6 as simply as:</para>
                        <para>
                            <programlisting>struct event6 
{ 
    event6(){} 
    template &lt;class Event> 
    event6(Event const&amp;){} 
}; //convertible from any event</programlisting>
                        </para>
                    </sect3>
                </sect2>
                <sect2>
                    <title>Flags</title>
                    <para>This <link xlink:href="examples/Flags.cpp">tutorial</link> is devoted to a
                        concept not defined in UML: flags. It has been added into MSM after proving
                        itself useful on many occasions. Please, do not be frightened as we are not
                        talking about ugly shortcuts made of an improbable collusion of
                        Booleans.</para>
                    <para>If you look into the Boost.Statechart documentation you'll find this
                        code:</para>
                    <programlisting>if ( ( state_downcast&lt; const NumLockOff * >() != 0 ) &amp;&amp;
     ( state_downcast&lt; const CapsLockOff * >() != 0 ) &amp;&amp;
     ( state_downcast&lt; const ScrollLockOff * >() != 0 ) )
                        </programlisting>
                    <para>While correct and found in many UML books, this can be error-prone and a
                        potential time-bomb when your state machine grows and you add new states or
                        orthogonal regions.</para>
                    <para>And most of all, it hides the real question, which would be “does my state
                        machine's current state define a special property”? In this special case
                        “are my keys in a lock state”? So let's apply the Fundamental Theorem of
                        Software Engineering and move one level of abstraction higher.</para>
                    <para>In our player example, let's say we need to know if the player has a
                        loaded CD. We could do the same:</para>
                    <programlisting>if ( ( state_downcast&lt; const Stopped * >() != 0 ) &amp;&amp;
     ( state_downcast&lt; const Open * >() != 0 ) &amp;&amp;
     ( state_downcast&lt; const Paused * >() != 0 ) &amp;&amp;
     ( state_downcast&lt; const Playing * >() != 0 )) </programlisting>
                    <para>Or flag these 4 states as CDLoaded-able. You add a flag_list type into
                        each flagged state:</para>
                    <para>
                        <programlisting>typedef mpl::vector1&lt;CDLoaded> flag_list;</programlisting>
                    </para>
                    <para>You can even define a list of flags, for example in Playing:</para>
                    <para>
                        <programlisting>typedef mpl::vector2&lt;PlayingPaused,CDLoaded> flag_list;</programlisting>
                    </para>
                    <para>This means that Playing supports both properties. To check if your player
                        has a loaded CD, check if your flag is active in the current state:</para>
                    <para>
                        <programlisting>player p; if (p.is_flag_active&lt;CDLoaded>()) ... </programlisting>
                    </para>
                    <para>And what if you have orthogonal regions? How to decide if a state machine
                        is in a flagged state? By default, you keep the same code and the current
                        states will be OR'ed, meaning if one of the active states has the flag, then
                        is_flag_active returns true. Of course, in some cases, you might want that
                        all of the active states are flagged for the state to be active. You can
                        also AND the active states:</para>
                    <para>
                        <programlisting>if (p.is_flag_active&lt;CDLoaded,player::Flag_AND>()) ...</programlisting>
                    </para>
                    <para>The following diagram displays the flag situation in the tutorial.</para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/FlagsTutorial.jpg" width="60%"
                                    scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                </sect2>
                <sect2>
                    <title><command xml:id="event-hierarchy"/>Event Hierarchy</title>
                    <para>There are cases where one needs transitions based on categories of events.
                        An example is text parsing. Let's say you want to parse a string and use a
                        state machine to manage your parsing state. You want to parse 4 digits and
                        decide to use a state for every matched digit. Your state machine could look
                        like:</para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/ParsingDigits.jpg" width="30%"
                                    scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                    <para>But how to detect the digit event? We would like to avoid defining 10
                        transitions on char_0, char_1... between two states as it would force us to
                        write 4 x 10 transitions and the compile-time would suffer. To solve this
                        problem, MSM supports the triggering of a transition on a subclass event.
                        For example, if we define digits as: </para>
                    <programlisting>struct digit {};
struct char_0 : public digit {}; </programlisting>
                    <para>And to the same for other digits, we can now fire char_0, char_1 events
                        and this will cause a transition with "digit" as trigger to be taken.</para>
                    <para>An <link xlink:href="examples/ParsingDigits.cpp">example</link> with
                        performance measurement, taken from the documentation of Boost.Xpressive
                        illustrates this example. You might notice that the performance is actually
                        very good (in this case even better).</para>
                </sect2>
                <sect2>
                    <title>Customizing a state machine / Getting more speed</title>
                    <para>MSM is offering many UML features at a high-speed, but sometimes, you just
                        need more speed and are ready to give up some features in exchange. A
                        process_event is handling several tasks: <itemizedlist>
                            <listitem>
                                <para>checking for terminate/interrupt states</para>
                            </listitem>
                            <listitem>
                                <para>handling the message queue (for entry/exit/transition actions
                                    generating themselves events)</para>
                            </listitem>
                            <listitem>
                                <para>handling deferred events</para>
                            </listitem>
                            <listitem>
                                <para>catching exceptions (or not)</para>
                            </listitem>
                            <listitem>
                                <para>handling the state switching and action calls</para>
                            </listitem>
                        </itemizedlist>Of these tasks, only the last one is absolutely necessary to
                        a state machine (its core job), the other ones are nice-to-haves which cost
                        CPU time. In many cases, it is not so important, but in embedded systems,
                        this can lead to ad-hoc state machine implementations. MSM detects by itself
                        if a concrete state machine makes use of terminate/interrupt states and
                        deferred events and deactivates them if not used. For the other two, if you
                        do not need them, you need to help by indicating it in your implementation.
                        This is done with two simple typedefs:<itemizedlist>
                            <listitem>
                                <para><code>no_exception_thrown</code> indicates that behaviors will
                                    never throw and MSM does not need to catch anything</para>
                            </listitem>
                            <listitem>
                                <para><code>no_message_queue</code> indicates that no action will
                                    itself generate a new event and MSM can save us the message
                                    queue.</para>
                            </listitem>
                        </itemizedlist>The third configuration possibility, explained <link
                            xlink:href="#basic-defer">here</link>, is to manually activate deferred
                        events, using <code>activate_deferred_events</code>. For example, the
                        following state machine sets all three configuration types:</para>
                    <programlisting>struct player_ : public msm::front::state_machine_def&lt;player_>
{
   // no need for exception handling or message queue
   typedef int no_exception_thrown;
   typedef int no_message_queue;
   // also manually enable deferred events
   typedef int activate_deferred_events
   ...// rest of implementation
   };</programlisting>
                    <para><emphasis role="underline">Important note</emphasis>: As exit pseudo
                        states are using the message queue to forward events out of a submachine,
                        the <code>no_message_queue</code> option cannot be used with state machines
                        containing an exit pseudo state.</para>
                </sect2>
                <sect2>
                    <title>Choosing the initial event</title>
                    <para>A state machine is started using the <code>start</code> method. This
                        causes the initial state's entry behavior to be executed. Like every entry
                        behavior, it becomes as parameter the event causing the state to be entered.
                        But when the machine starts, there was no event triggered. In this case, MSM
                        sends <code>msm::back::state_machine&lt;...>::InitEvent</code>, which might
                        not be the default you'd want. For this special case, MSM provides a
                        configuration mechanism in the form of a typedef. If the state machine's
                        front-end definition provides an initial_event typedef set to another event,
                        this event will be used. For example:</para>
                    <programlisting>struct my_initial_event{};
struct player_ : public msm::front::state_machine_def&lt;player_>{
...
typedef my_initial_event initial_event; 
};</programlisting>
                </sect2>
                <sect2>
                    <title> Containing state machine (deprecated)</title>
                    <para>This feature is still supported in MSM for backward compatibility but made
                        obsolete by the fact that every guard/action/entry action/exit action get
                        the state machine passed as argument and might be removed at a later
                        time.</para>
                    <para>All of the states defined in the state machine are created upon state
                        machine construction. This has the huge advantage of a reduced syntactic
                        noise. The cost is a small loss of control for the user on the state
                        creation and access. But sometimes you needed a way for a state to get
                        access to its containing state machine. Basically, a state needs to change
                        its declaration to:</para>
                    <programlisting>struct Stopped : public msm::front::state&lt;sm_ptr></programlisting>
                    <para>And to provide a set_sm_ptr function: <code>void set_sm_ptr(player*
                            pl)</code></para>
                    <para>to get a pointer to the containing state machine. The same applies to
                        terminate_state / interrupt_state and entry_pseudo_state /
                        exit_pseudo_state. </para>
                </sect2>
            </sect1>
            <sect1>
                <title><command xml:id="functor-front-end"/>Functor front-end</title>
                <para>The functor front-end is the preferred front-end at the moment. It is more
                    powerful than the standard front-end and has a more readable transition table.
                    It also makes it easier to reuse parts of state machines. Like <command
                        xlink:href="#eUML-front-end">eUML</command>, it also comes with a good deal
                    of predefined actions. Actually, eUML generates a functor front-end through
                    Boost.Typeof and Boost.Proto so both offer the same functionality.</para>
                <para>The rows which MSM offered in the previous front-end come in different
                    flavors. We saw the a_row, g_row, _row, row, not counting internal rows. This is
                    already much to know, so why define new rows? These types have some
                    disadvantages: <itemizedlist>
                        <listitem>
                            <para>They are more typing and information than we would wish. This
                                means syntactic noise and more to learn.</para>
                        </listitem>
                        <listitem>
                            <para>Function pointers are weird in C++.</para>
                        </listitem>
                        <listitem>
                            <para>The action/guard signature is limited and does not allow for more
                                variations of parameters (source state, target state, current state
                                machine, etc.)</para>
                        </listitem>
                        <listitem>
                            <para>It is not easy to reuse action code from a state machine to
                                another.</para>
                        </listitem>
                    </itemizedlist></para>
                <sect2>
                    <title> Transition table </title>
                    <para>We can change the definition of the simple tutorial's transition table
                        to:</para>
                    <programlisting> 
struct transition_table : mpl::vector&lt;
//    Start     Event        Target      Action                      Guard 
//   +---------+------------+-----------+---------------------------+----------------------------+ 
Row  &lt; Stopped , play       ,  Playing  , start_playback            , none                       >,
Row  &lt; Stopped , open_close ,  Open     , open_drawer               , none                       >,
Row  &lt; Stopped , stop       ,  Stopped  , none                      , none                       >,
//   +---------+------------+-----------+---------------------------+----------------------------+ 
Row  &lt; Open    , open_close ,  Empty    , close_drawer              , none                       >,
//   +---------+------------+-----------+---------------------------+----------------------------+ 
Row  &lt; Empty   , open_close ,  Open     , open_drawer               , none                       >,
Row  &lt; Empty   , cd_detected,  Stopped  , store_cd_info             , good_disk_format           >,
g_row&lt; Empty   , cd_detected,  Playing  , &amp;player_::store_cd_info   , &amp;player_::auto_start       >,
//   +---------+------------+-----------+---------------------------+----------------------------+ 
Row  &lt; Playing , stop       ,  Stopped  , stop_playback             , none                       >,
Row  &lt; Playing , pause      ,  Paused   , pause_playback            , none                       >,
Row  &lt; Playing , open_close ,  Open     , stop_and_open             , none                       >,
//   +---------+------------+-----------+---------------------------+----------------------------+ 
Row  &lt; Paused  , end_pause  ,  Playing  , resume_playback           , none                       >,
Row  &lt; Paused  , stop       ,  Stopped  , stop_playback             , none                       >,
Row  &lt; Paused  , open_close ,  Open     , stop_and_open             , none                       >
//   +---------+------------+-----------+---------------------------+----------------------------+ 
> {};
                        </programlisting>
                    <para>Transitions are now of type "Row" with exactly 5 template arguments:
                        source state, event, target state, action and guard. Wherever there is
                        nothing (for example actions and guards), write "none". Actions and guards
                        are no more methods but functors getting as arguments the detected event,
                        the state machine, source and target state:</para>
                    <programlisting>struct store_cd_info 
{ 
    template &lt;class Fsm,class Evt,class SourceState,class TargetState> 
    void operator()(Evt const&amp;, Fsm&amp; fsm, SourceState&amp;,TargetState&amp; ) 
    {
        cout &lt;&lt; "player::store_cd_info" &lt;&lt; endl;
                            fsm.process_event(play());
    } 
}; </programlisting>
                    <para>The advantage of functors compared to functions are that functors are
                        generic and reusable. They also allow passing more parameters than just
                        events. The guard functors are the same but have an operator() returning a
                        bool.</para>
                    <para>It is also possible to mix rows from different front-ends. To show this, a
                        g_row has been left in the transition table. <emphasis role="underline"
                            >Note:</emphasis> in case the action functor is used in the transition
                        table of a state machine contained inside a top-level state machine, the
                        “fsm” parameter refers to the lowest-level state machine (referencing this
                        action), not the top-level one.</para>
                    <para>To illustrate the reusable point, MSM comes with a whole set of predefined
                        functors. Please refer to eUML for the <link xlink:href="#Reference-begin"
                            >full list</link>. For example, we are now going to replace the first
                        action by an action sequence and the guard by a more complex functor.</para>
                    <para>We decide we now want to execute two actions in the first transition
                        (Stopped -> Playing). We only need to change the action start_playback to
                        <programlisting>ActionSequence_&lt; mpl::vector&lt;some_action, start_playback> ></programlisting>and
                        now will execute some_action and start_playback every time the transition is
                        taken. ActionSequence_ is a functor calling each action of the mpl::vector
                        in sequence.</para>
                    <para>We also want to replace good_disk_format by a condition of the type:
                        “good_disk_format &amp;&amp; (some_condition || some_other_condition)”. We
                        can achieve this using And_ and Or_ functors:
                        <programlisting>And_&lt;good_disk_format,Or_&lt; some_condition , some_other_condition> ></programlisting>It
                        even starts looking like functional programming. MSM ships with functors for
                        operators, state machine usage, STL algorithms or container methods.</para>
                </sect2>
                <sect2>
                    <title>Defining states with entry/exit actions</title>
                    <para>You probably noticed that we just showed a different transition table and
                        that we even mixed rows from different front-ends. This means that you can
                        do this and leave the definitions for states unchanged. Most examples are
                        doing this as it is the simplest solution. You still enjoy the simplicity of
                        the first front-end with the extended power of the new transition types.
                        This <link xlink:href="examples/SimpleWithFunctors.cpp">tutorial</link>,
                        adapted from the earlier example does just this.</para>
                    <para>Of course, it is also possible to define states where entry and exit
                        actions are also provided as functors as these are generated by eUML and
                        both front-ends are equivalent. For example, we can define a state
                        as:</para>
                    <programlisting>struct Empty_Entry 
{ 
    template &lt;class Event,class Fsm,class State> 
    void operator()(Event const&amp;,Fsm&amp;,State&amp;) 
    {
        ... 
    } 
}; // same for Empty_Exit
struct Empty : public msm::front::euml::func_state&lt;Empty_Entry,Empty_Exit>{};</programlisting>
                    <para>This also means that you can, like in the transition table, write entry /
                        exit actions made of more complicated action combinations. The previous
                        example can therefore <link xlink:href="examples/SimpleWithFunctors2.cpp">be
                            rewritten</link>.</para>
                    <para>Usually, however, one will probably use the standard state definition as
                        it provides the same capabilities as this front-end state definition, unless
                        one needs some of the shipped predefined functors or is a fan of functional
                        programming.</para>
                </sect2>
                <sect2>
                    <title><command xml:id="functor-front-end-actions"/>What do you actually do inside actions / guards (Part 2)?</title>
                    <para>Using the basic front-end, we saw how to pass data to actions through the
                        event, that data common to all states could be stored in the state machine,
                        state relevant data could be stored in the state and access as template
                        parameter in the entry / exit actions. What was however missing was the
                        capability to access relevant state data in the transition action. This is
                        possible with this front-end. A transition's source and target state are
                        also given as arguments. If the current calculation's state was to be found
                        in the transition's source state (whatever it is), we could access
                        it:</para>
                    <programlisting>struct send_rocket 
{ 
    template &lt;class Fsm,class Evt,class SourceState,class TargetState> 
    void operator()(Evt const&amp;, Fsm&amp; fsm, SourceState&amp; src,TargetState&amp; ) 
    {
        fire_rocket(evt.direction, src.current_calculation);
    } 
}; </programlisting>
                <para>It was a little awkward to generate new events inside actions with the basic
                front-end. With the functor front-end it is much cleaner:</para>
                    <programlisting>struct send_rocket 
{ 
    template &lt;class Fsm,class Evt,class SourceState,class TargetState> 
    void operator()(Evt const&amp; evt, Fsm&amp; fsm, SourceState&amp; src,TargetState&amp;) 
    {
        fire_rocket(evt.direction, src.current_calculation);
        fsm.process_event(rocket_launched());
    } 
}; </programlisting>                    
                </sect2>
                <sect2>
                    <title>Defining a simple state machine</title>
                    <para>Like states, state machines can be defined using the previous front-end,
                        as the previous example showed, or with the functor front-end, which allows
                        you to define a state machine entry and exit functions as functors, as in
                            <link xlink:href="examples/SimpleWithFunctors2.cpp">this
                        example</link>.</para>
                </sect2>
                <sect2>
                    <title>Anonymous transitions</title>
                    <para>Anonymous (completion) transitions are transitions without a named event.
                        We saw how this front-end uses <code>none</code> when no action or guard is
                        required. We can also use <code>none</code> instead of an event to mark an
                        anonymous transition. For example, the following transition makes an
                        immediate transition from State1 to State2:</para>
                    <programlisting>Row &lt; State1 , none , State2 ></programlisting>
                    <para>The following transition does the same but calling an action in the
                        process:</para>
                    <programlisting>Row &lt; State1 , none , State2 , State1ToState2, none ></programlisting>
                    <para>The following diagram shows an example and its <link
                            xlink:href="examples/AnonymousTutorialWithFunctors.cpp"
                            >implementation</link>:</para>
                    <para><inlinemediaobject>
                            <imageobject>
                                <imagedata fileref="images/Anonymous.jpg" width="70%" scalefit="1"/>
                            </imageobject>
                        </inlinemediaobject></para>
                </sect2>
                <sect2>
                    <title><command xml:id="functor-internal-transitions"/>Internal
                        transitions</title>
                    <para>The <link xlink:href="examples/SimpleTutorialInternalFunctors.cpp"
                            >following example</link> uses internal transitions with the functor
                        front-end. As for the simple standard front-end, both methods of defining
                        internal transitions are supported:<itemizedlist>
                            <listitem>
                                <para>providing a <code>Row</code> in the state machine's transition
                                    table with <code>none</code> as target state defines an internal
                                    transition.</para>
                            </listitem>
                            <listitem>
                                <para>providing an <code>internal_transition_table</code> made of
                                        <code>Internal</code> rows inside a state or submachine
                                    defines UML-conform internal transitions with higher
                                    priority.</para>
                            </listitem>
                            <listitem>
                                <para>transitions defined inside
                                        <code>internal_transition_table</code> require no source or
                                    target state as the source state is known (<code>Internal</code>
                                    really are <code>Row</code> without a source or target state)
                                    .</para>
                            </listitem>
                        </itemizedlist>Like for the <command xlink:href="#internal-transitions-note"
                            >standard front-end internal transitions</command>, internal transition
                        tables are added into the main state machine's table, thus allowing you to
                        distribute the transition table definition and reuse states.</para>
                    <para>There is an added bonus offered for submachines, which can have both the
                        standard transition_table and an internal_transition_table (which has higher
                        priority). This makes it easier if you decide to make a full submachine from
                        a state later. It is also slightly faster than the standard alternative,
                        adding orthogonal regions, because event dispatching will, if accepted by
                        the internal table, not continue to the subregions. This gives you a O(1)
                        dispatch instead of O(number of regions). While the example is with eUML,
                        the same is also possible with this front-end.</para>
                </sect2>
            </sect1>
            <sect1>
                <title><command xml:id="eUML-front-end"/>eUML (experimental)</title>
                <para><emphasis role="underline">Important note</emphasis>: eUML requires a compiler
                    supporting Boost.Typeof. More generally, eUML has experimental status because
                    some compilers will start crashing when a state machine becomes too big (usually
                    when you write huge actions).</para>
                <para>The previous front-ends are simple to write but still force an amount of
                    noise, mostly MPL types, so it would be nice to write code looking like C++
                    (with a C++ action language) directly inside the transition table, like UML
                    designers like to do on their state machine diagrams. If it were functional
                    programming, it would be even better. This is what eUML is for.</para>
                <para>eUML is a Boost.Proto and Boost.Typeof-based compile-time domain specific
                    embedded language. It provides grammars which allow the definition of
                    actions/guards directly inside the transition table or entry/exit in the state
                    definition. There are grammars for actions, guards, flags, attributes, deferred
                    events, initial states.</para>
                <para>It also relies on Boost.Typeof as a wrapper around the new decltype C++0x
                    feature to provide a compile-time evaluation of all the grammars. Unfortunately,
                    all the underlying Boost libraries are not Typeof-enabled, so for the moment,
                    you will need a compiler where Typeof is supported (like VC9-10, g++ >=
                    4.3).</para>
                <para>Examples will be provided in the next paragraphs. You need to include eUML
                    basic features: </para>
                <para>
                    <programlisting>#include &lt;msm/front/euml/euml.hpp></programlisting>
                </para>
                <para>To add STL support (at possible cost of longer compilation times), include: </para>
                <para>
                    <programlisting>#include &lt;msm/front/euml/stl.hpp></programlisting>
                </para>
                <para>eUML is defined in the namespace <code>msm::front::euml</code>.</para>
                <sect2>
                    <title>Transition table</title>
                    <para>A transition can be defined using eUML as: </para>
                    <para>
                        <programlisting>source + event [guard] / action == target</programlisting>
                    </para>
                    <para>or as</para>
                    <para>
                        <programlisting>target == source + event [guard] / action</programlisting>
                    </para>
                    <para>The first version looks like a drawn transition in a diagram, the second
                        one seems natural to a C++ developer.</para>
                    <para>The simple transition table written with the <command
                            xlink:href="#functor-front-end">functor front-end</command> can now be
                        written as:</para>
                    <programlisting>BOOST_MSM_EUML_TRANSITION_TABLE(( 
Stopped + play [some_guard] / (some_action , start_playback)  == Playing ,
Stopped + open_close/ open_drawer                             == Open    ,
Stopped + stop                                                == Stopped ,
Open    + open_close / close_drawer                           == Empty   ,
Empty   + open_close / open_drawer                            == Open    ,
Empty   + cd_detected [good_disk_format] / store_cd_info      == Stopped
),transition_table)                       </programlisting>
                    <para>Or, using the alternative notation, it can be:</para>
                    <programlisting>BOOST_MSM_EUML_TRANSITION_TABLE(( 
Playing  == Stopped + play [some_guard] / (some_action , start_playback) ,
Open     == Stopped + open_close/ open_drawer                            ,
Stopped  == Stopped + stop                                               ,
Empty    == Open    + open_close / close_drawer                          ,
Open     == Empty   + open_close / open_drawer                           ,
Stopped  == Empty   + cd_detected [good_disk_format] / store_cd_info
),transition_table)           </programlisting>
                    <para>The transition table now looks like a list of (readable) rules with little
                        noise.</para>
                    <para>UML defines guards between “[ ]” and actions after a “/”, so the chosen
                        syntax is already more readable for UML designers. UML also allows designers
                        to define several actions sequentially (our previous ActionSequence_)
                        separated by a comma. The first transition does just this: two actions
                        separated by a comma and enclosed inside parenthesis to respect C++ operator
                        precedence.</para>
                    <para>If this seems to you like it will cost you run-time performance, don't
                        worry, eUML is based on typeof (or decltype) which only evaluates the
                        parameters to BOOST_MSM_EUML_TRANSITION_TABLE and no run-time cost occurs.
                        Actually, eUML is only a metaprogramming layer on top of "standard" MSM
                        metaprogramming and this first layer generates the previously-introduced
                            <command xlink:href="#functor-front-end">functor
                        front-end</command>.</para>
                    <para>UML also allows designers to define more complicated guards, like
                        [good_disk_format &amp;&amp; (some_condition || some_other_condition)]. This
                        was possible with our previously defined functors, but using a complicated
                        template syntax. This syntax is now possible exactly as written, which means
                        without any syntactic noise at all.</para>
                </sect2>
                <sect2>
                    <title>A simple example: rewriting only our transition table</title>
                    <para>As an introduction to eUML, we will rewrite our tutorial's transition
                        table using eUML. This will require two or three changes, depending on the compiler:<itemizedlist>
                            <listitem>
                                <para>events must inherit from msm::front::euml::euml_event&lt;
                                    event_name ></para>
                            </listitem>
                            <listitem>
                                <para>states must inherit from msm::front::euml::euml_state&lt;
                                    state_name ></para>
                            </listitem>
                            <listitem>
                                <para>with VC, states must be declared before the front-end</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>We now can write the transition table like just shown, using
                        BOOST_MSM_EUML_DECLARE_TRANSITION_TABLE instead of
                        BOOST_MSM_EUML_TRANSITION_TABLE. The <link
                            xlink:href="examples/SimpleTutorialWithEumlTable.cpp">implementation</link> is pretty
                        straightforward.</para>
                    <para>The <link
                        xlink:href="examples/CompositeTutorialWithEumlTable.cpp">composite</link> implementation is slightly trickier because the submachine
                        has to be a msm::back::state_machine and a msm::front::euml::state. For
                        example:</para>
                    <programlisting>struct front_end : public msm::front::state_machine_def&lt;front_end>
{
...
};
struct submachine : public boost::msm::back::state_machine&lt;front_end>,
                    public msm::front::euml::euml_state&lt;submachine>
{
};</programlisting>
                    <para>Unfortunately, there is a bug with VC, which appears from time to time and
                        causes in a stack overflow. If you get a warning that the program is
                        recursive on all paths, revert to either standard eUML or another front-end
                        as Microsoft doesn't seem to intend to fix it.</para>
                    <para>We now have a new, more readable transition table with few changes to our
                        example. eUML can do much more so please follow the guide.</para>
                </sect2>
                <sect2>
                    <title>Defining events, actions and states with entry/exit actions</title>
                    <sect3>
                        <title>Events</title>
                        <para>Events must be proto-enabled. To achieve this, they must inherit from
                            a proto terminal (euml_event&lt;event-name>). eUML also provides a macro
                            to make this easier:</para>
                        <para>
                            <programlisting>BOOST_MSM_EUML_EVENT(play)</programlisting>
                        </para>
                        <para>This declares an event type and an instance of this type called
                                <code>play</code>, which is now ready to use in state or transition
                            behaviors.</para>
                        <para>There is a second macro, BOOST_MSM_EUML_EVENT_WITH_ATTRIBUTES, which
                            takes as second parameter the attributes an event will contain, using
                            the <command xlink:href="#eUML-attributes">attribute
                            syntax</command>.</para>
                        <para><emphasis role="underline">Note</emphasis>: as we now have events
                            defined as instances instead of just types, can we still process an
                            event by creating one on the fly, like:
                                <code>fsm.process_event(play());</code> or do we have to write:
                                <code>fsm.process_event(play);</code></para>
                        <para>The answer is you can do both. The second one is easier but unlike
                            other front-ends, the second uses a defined operator(), which creates an
                            event on the fly.</para>
                    </sect3>
                    <sect3>
                        <title>Actions</title>
                        <para>Actions (returning void) and guards (returning a bool) are defined
                            like previous functors, with the difference that they also must be
                            proto-enabled. This can be done by inheriting from euml_action&lt;
                            functor-name >. eUML also provides a macro:</para>
                        <programlisting>BOOST_MSM_EUML_ACTION(some_condition)
{
    template &lt;class Fsm,class Evt,class SourceState,class TargetState>
    bool operator()(Evt const&amp; ,Fsm&amp; ,SourceState&amp;,TargetState&amp; ) 
    { return true; }
}; </programlisting>
                        <para>Like for events, this macro declares a functor type and an instance
                            for use in transition or state behaviors.</para>
                        <para>It is possible to use the same action grammar from the transition
                            table to define state entry and exit behaviors. So
                                <code>(action1,action2)</code> is a valid entry or exit behavior
                            executing both actions in turn.</para>
                        <para>The state functors have a slightly different signature as there is no
                            source and target state but only a current state (entry/exit actions are
                            transition-independent), for example:</para>
                        <programlisting>BOOST_MSM_EUML_ACTION(Empty_Entry)
{
    template &lt;class Evt,class Fsm,class State>
    void operator()(Evt const&amp; ,Fsm&amp; ,State&amp; ) { ... }                           
    }; </programlisting>
                        <para><command xml:id="eUML-reuse-functor"/>It is also possible to reuse the functors from the functor front-end.
                            The syntax is however slightly less comfortable as we need to pretend
                            creating one on the fly for typeof. For example:</para>
                        <programlisting>struct start_playback 
{
        template &lt;class Fsm,class Evt,class SourceState,class TargetState>
        void operator()(Evt const&amp; ,Fsm&amp;,SourceState&amp; ,TargetState&amp; )
        {
         ...            
        }
};
BOOST_MSM_EUML_TRANSITION_TABLE((
Playing   == Stopped  + play        / start_playback() ,
...
),transition_table)</programlisting>                        
                    </sect3>
                    <sect3>
                        <title>States</title>
                        <para>There is also a macro for states. This macro has 2 arguments, first
                            the expression defining the state, then the state (instance)
                            name:</para>
                        <programlisting>BOOST_MSM_EUML_STATE((),Paused)</programlisting>
                        <para>This defines a simple state without entry or exit action. You can
                            provide in the expression parameter the state behaviors (entry and exit)
                            using the action grammar, like in the transition table:</para>
                        <programlisting>BOOST_MSM_EUML_STATE(((Empty_Entry,Dummy_Entry)/*2 entryactions*/,
                       Empty_Exit/*1 exit action*/ ),
                     Empty)</programlisting>
                        <para>This means that Empty is defined as a state with an entry action made
                            of two sub-actions, Empty_Entry and Dummy_Entry (enclosed inside
                            parenthesis), and an exit action, Empty_Exit.</para>
                        <para>There are several possibilitites for the <command
                                xml:id="eUML-build-state"/> expression syntax:<itemizedlist>
                                <listitem>
                                    <para>(): state without entry or exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1): state with entry but no exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2): state with entry and exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes): state with entry and exit
                                        action, defining some attributes (read further on).</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes,Configure): state with entry and
                                        exit action, defining some attributes (read further on) and
                                        flags (standard MSM flags) or deferred events (standard MSM
                                        deferred events).</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes,Configure,Base): state with entry
                                        and exit action, defining some attributes (read further on),
                                        flags and deferred events (plain msm deferred events) and a
                                        non-default base state (as defined in standard MSM).</para>
                                </listitem>
                            </itemizedlist></para>
                        <para>no_action is also defined, which does, well, nothing except being a
                            placeholder (needed for example as entry action if we have no entry but
                            an exit). Expr1 and Expr2 are a sequence of actions, obeying the same
                            action grammar as in the transition table (following the “/”
                            symbol).</para>
                        <para>The BOOST_MSM_EUML_STATE macro will allow you to define most common
                            states, but sometimes you will need more, for example provide in your
                            states some special behavior. In this case, you will have to do the
                            macro's job by hand, which is not very complicated. The state will need
                            to inherit from <code>msm::front::state&lt;></code>, like any state, and
                            from <code>euml_state&lt;state-name></code> to be proto-enabled. You
                            will then need to declare an instance for use in the transition table.
                            For example:</para>
                        <programlisting>struct Empty_impl : public msm::front::state&lt;> , public euml_state&lt;Empty_impl> 
{
   void activate_empty() {std::cout &lt;&lt; "switching to Empty " &lt;&lt; std::endl;}
   template &lt;class Event,class Fsm>
   void on_entry(Event const&amp; evt,Fsm&amp;fsm){...}
   template &lt;class Event,class Fsm>
   void on_exit(Event const&amp; evt,Fsm&amp;fsm){...}
};
//instance for use in the transition table
Empty_impl const Empty;</programlisting>
                        <para>Notice also that we defined a method named activate_empty. We would
                            like to call it inside a behavior. This can be done using the
                            BOOST_MSM_EUML_METHOD macro. </para>
                        <programlisting>BOOST_MSM_EUML_METHOD(ActivateEmpty_,activate_empty,activate_empty_,void,void)</programlisting>
                        <para>The first parameter is the name of the underlying functor, which you
                            could use with the functor front-end, the second is the state method
                            name, the third is the eUML-generated function, the fourth and fifth the
                            return value when used inside a transition or a state behavior. You can
                            now use this inside a transition:</para>
                        <programlisting>Empty == Open + open_close / (close_drawer,activate_empty_(target_))</programlisting>
                    </sect3>              
                </sect2>
                <sect2>
                    <title>Wrapping up a simple state machine and first complete examples</title>
                    <para>You can reuse the state machine definition method from the standard
                        front-end and simply replace the transition table by this new one. You can
                        also use eUML to define a state machine "on the fly" (if, for example, you
                        need to provide an on_entry/on_exit for this state machine as a functor).
                        For this, there is also a macro, <command xml:id="eUML-build-sm"
                        />BOOST_MSM_EUML_DECLARE_STATE_MACHINE, which has 2 arguments, an expression
                        describing the state machine and the state machine name. The expression has
                        up to 8 arguments:<itemizedlist>
                            <listitem>
                                <para>(Stt, Init): simplest state machine where only the transition
                                    table and initial state(s) are defined.</para>
                            </listitem>
                            <listitem>
                                <para>(Stt, Init, Expr1): state machine where the transition table,
                                    initial state and entry action are defined.</para>
                            </listitem>
                            <listitem>
                                <para>(Stt, Init, Expr1, Expr2): state machine where the transition
                                    table, initial state, entry and exit actions are defined.</para>
                            </listitem>
                            <listitem>
                                <para>(Stt, Init, Expr1, Expr2, Attributes): state machine where the
                                    transition table, initial state, entry and exit actions are
                                    defined. Furthermore, some attributes are added (read further
                                    on).</para>
                            </listitem>
                            <listitem>
                                <para>(Stt, Init, Expr1, Expr2, Attributes, Configure): state
                                    machine where the transition table, initial state, entry and
                                    exit actions are defined. Furthermore, some attributes (read
                                    further on), flags, deferred events and <link
                                        xlink:href="#eUML-Configuration">configuration
                                        capabilities</link> (no message queue / no exception
                                    catching) are added.</para>
                            </listitem>
                            <listitem>
                                <para>(Stt, Init, Expr1, Expr2, Attributes, Flags, Deferred , Base):
                                    state machine where the transition table, initial state, entry
                                    and exit actions are defined. Furthermore, attributes (read
                                    further on), flags , deferred events and configuration
                                    capabilities (no message queue / no exception catching) are
                                    added and a non-default base state (see the <link
                                        xlink:href="#backend-base-state">back-end
                                    description</link>) is defined.</para>
                            </listitem>
                        </itemizedlist>For example, a minimum state machine could be defined
                        as:</para>
                    <programlisting>BOOST_MSM_EUML_TRANSITION_TABLE(( 
),transition_table)                       </programlisting>
                    <programlisting>BOOST_MSM_EUML_DECLARE_STATE_MACHINE((transition_table,init_ &lt;&lt; Empty ),
                                     player_)</programlisting>
                    <para>Please have a look at the player tutorial written using eUML's <link
                            xlink:href="examples/SimpleTutorialEuml2.cpp">first syntax</link> and
                            <link xlink:href="examples/SimpleTutorialEuml.cpp">second syntax</link>.
                        The BOOST_MSM_EUML_DECLARE_ATTRIBUTE macro, to which we will get back
                        shortly, declares attributes given to an eUML type (state or event) using
                        the <command xlink:href="#eUML-attributes">attribute
                        syntax</command>.</para>
                </sect2>
                <sect2>
                    <title>Defining a submachine</title>
                    <para>Defining a submachine (see <link
                            xlink:href="examples/CompositeTutorialEuml.cpp">tutorial</link>) with
                        other front-ends simply means using a state which is a state machine in the
                        transition table of another state machine. This is the same with eUML. One
                        only needs define a second state machine and reference it in the transition
                        table of the containing state machine.</para>
                    <para>Unlike the state or event definition macros,
                        BOOST_MSM_EUML_DECLARE_STATE_MACHINE defines a type, not an instance because
                        a type is what the back-end requires. This means that you will need to
                        declare yourself an instance to reference your submachine into another state
                        machine, for example:</para>
                    <programlisting>BOOST_MSM_EUML_DECLARE_STATE_MACHINE(...,Playing_)
typedef msm::back::state_machine&lt;Playing_> Playing_type;
Playing_type const Playing;</programlisting>
                    <para>We can now use this instance inside the transition table of the containing
                        state machine:</para>
                    <programlisting>Paused == Playing + pause / pause_playback</programlisting>
                </sect2>
                <sect2>
                    <title>
                        <command xml:id="eUML-attributes"/>Attributes / Function call</title>
                    <para>We now want to make our grammar more useful. Very often, one needs only
                        very simple action methods, for example ++Counter or Counter > 5 where
                        Counter is usually defined as some attribute of the class containing the
                        state machine. It seems like a waste to write a functor for such a simple
                        action. Furthermore, states within MSM are also classes so they can have
                        attributes, and we would also like to provide them with attributes. </para>
                    <para>If you look back at our examples using the <link
                            xlink:href="examples/SimpleTutorialEuml2.cpp">first</link> and <link
                            xlink:href="examples/SimpleTutorialEuml.cpp">second</link> syntaxes, you
                        will find a BOOST_MSM_EUML_DECLARE_ATTRIBUTE and a BOOST_MSM_EUML_ATTRIBUTES
                        macro. The first one declares possible attributes:</para>
                    <programlisting>BOOST_MSM_EUML_DECLARE_ATTRIBUTE(std::string,cd_name)
BOOST_MSM_EUML_DECLARE_ATTRIBUTE(DiskTypeEnum,cd_type)</programlisting>
                    <para>This declares two attributes: cd_name of type std::string and cd_type of
                        type DiskTypeEnum. These attributes are not part of any event or state in
                        particular, we just declared a name and a type. Now, we can add attributes
                        to our cd_detected event using the second one:</para>
                    <programlisting>BOOST_MSM_EUML_ATTRIBUTES((attributes_ &lt;&lt; cd_name &lt;&lt; cd_type ), 
                          cd_detected_attributes)</programlisting>
                    <para>This declares an attribute list which is not linked to anything in
                        particular yet. It can be attached to a state or an event. For example, if
                        we want the event cd_detected to have these defined attributes we
                        write:</para>
                    <programlisting>BOOST_MSM_EUML_EVENT_WITH_ATTRIBUTES(cd_detected,cd_detected_attributes)</programlisting>
                    <para>For states, we use the BOOST_MSM_EUML_STATE macro, which has an expression
                        form where one can provide attributes. For example:</para>
                    <programlisting>BOOST_MSM_EUML_STATE((no_action /*entry*/,no_action/*exit*/,
                      attributes_ &lt;&lt; cd_detected_attributes),
                     some_state)</programlisting>
                    <para>OK, great, we now have a way to add attributes to a class, which we could
                        have done more easily, so what is the point? The point is that we can now
                        reference these attributes directly, at compile-time, in the transition
                        table. For example, in the example, you will find this transition:</para>
                    <programlisting>Stopped==Empty+cd_detected[good_disk_format&amp;&amp;(event_(cd_type)==Int_&lt;DISK_CD>())] </programlisting>
                    <para>Read event_(cd_type) as event_->cd_type with event_ a type generic for
                        events, whatever the concrete event is (in this particular case, it happens
                        to be a cd_detected as the transition shows).</para>
                    <para>The main advantage of this feature is that you do not need to define a new
                        functor and you do not need to look inside the functor to know what it does,
                        you have all at hand.</para>
                    <para>MSM provides more generic objects for state machine types:<itemizedlist>
                            <listitem>
                                <para>event_ : used inside any action, the event triggering the
                                    transition</para>
                            </listitem>
                            <listitem>
                                <para>state_: used inside entry and exit actions, the entered /
                                    exited state</para>
                            </listitem>
                            <listitem>
                                <para>source_: used inside a transition action, the source
                                    state</para>
                            </listitem>
                            <listitem>
                                <para>target_: used inside a transition action, the target
                                    state</para>
                            </listitem>
                            <listitem>
                                <para>fsm_: used inside any action, the (lowest-level) state machine
                                    processing the transition</para>
                            </listitem>
                            <listitem>
                                <para>Int_&lt;int value>: a functor representing an int</para>
                            </listitem>
                            <listitem>
                                <para>Char_&lt;value>: a functor representing a char</para>
                            </listitem>
                            <listitem>
                                <para>Size_t_&lt;value>: a functor representing a size_t</para>
                            </listitem>
                            <listitem>
                                <para>String_&lt;mpl::string> (boost >= 1.40): a functor
                                    representing a string.</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>These helpers can be used in two different ways:<itemizedlist>
                            <listitem>
                                <para>helper(attribute_name) returns the attribute with name
                                    attribute_name</para>
                            </listitem>
                            <listitem>
                                <para>helper returns the state / event type itself.</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>The second form is helpful if you want to provide your states with their
                        own methods, which you also want to use inside the transition table. In the
                            <link xlink:href="examples/SimpleTutorialEuml.cpp">above
                        tutorial</link>, we provide Empty with an activate_empty method. We would
                        like to create a eUML functor and call it from inside the transition table.
                        This is done using the MSM_EUML_METHOD / MSM_EUML_FUNCTION macros. The first
                        creates a functor to a method, the second to a free function. In the
                        tutorial, we write:</para>
                    <programlisting>MSM_EUML_METHOD(ActivateEmpty_,activate_empty,activate_empty_,void,void)</programlisting>
                    <para>The first parameter is the functor name, for use with the functor
                        front-end. The second is the name of the method to call. The third is the
                        function name for use with eUML, the fourth is the return type of the
                        function if used in the context of a transition action, the fifth is the
                        result type if used in the context of a state entry / exit action (usually
                        fourth and fifth are the same). We now have a new eUML function calling a
                        method of "something", and this "something" is one of the five previously
                        shown generic helpers. We can now use this in a transition, for
                        example:</para>
                    <programlisting>Empty == Open + open_close / (close_drawer,activate_empty_(target_))</programlisting>
                    <para>The action is now defined as a sequence of two actions: close_drawer and
                        activate_empty, which is called on the target itself. The target being Empty
                        (the state defined left), this really will call Empty::activate_empty().
                        This method could also have an (or several) argument(s), for example the
                        event, we could then call activate_empty_(target_ , event_).</para>
                    <para>More examples can be found in the <link
                            xlink:href="examples/CompilerStressTestEuml.cpp">terrible compiler
                            stress test</link>, the <link xlink:href="examples/SimpleTimer.cpp"
                            >timer example</link> or in the <link
                            xlink:href="examples/iPodSearchEuml.cpp">iPodSearch with eUML</link>
                        (for String_ and more).</para>
                </sect2>
                <sect2>
                    <title>Orthogonal regions, flags, event deferring</title>
                    <para>Defining orthogonal regions really means providing more initial states. To
                        add more initial states, “shift left” some, for example, if we had another
                        initial state named AllOk :</para>
                    <programlisting>BOOST_MSM_EUML_DECLARE_STATE_MACHINE((transition_table,
                                     init_ &lt;&lt; Empty &lt;&lt; AllOk ),
                                    player_)</programlisting>
                    <para>You remember from the <command xlink:href="#eUML-build-state"
                            >BOOST_MSM_EUML_STATE </command> and <command
                            xlink:href="#eUML-build-sm"
                            >BOOST_MSM_EUML_DECLARE_STATE_MACHINE</command> signatures that just
                        after attributes, we can define flags, like in the basic MSM front-end. To
                        do this, we have another "shift-left" grammar, for example:</para>
                    <programlisting>BOOST_MSM_EUML_STATE((no_action,no_action, attributes_ &lt;&lt;no_attributes_, 
                      /* flags */ configure_&lt;&lt; PlayingPaused &lt;&lt; CDLoaded), 
                    Paused)</programlisting>
                    <para>We now defined that Paused will get two flags, PlayingPaused and CDLoaded,
                        defined, with another macro:</para>
                    <programlisting>BOOST_MSM_EUML_FLAG(CDLoaded)</programlisting>
                    <para>This corresponds to the following basic front-end definition of
                        Paused:</para>
                    <programlisting>struct Paused : public msm::front::state&lt;>
{ 
   typedef mpl::vector2&lt;PlayingPaused,CDLoaded> flag_list; 
};</programlisting>
                    <para>Under the hood, what you get really is a mpl::vector2.</para>
                    <para><emphasis role="underline">Note</emphasis>: As we use the version of
                        BOOST_MSM_EUML_STATE's expression with 4 arguments, we need to tell eUML
                        that we need no attributes. Similarly to a <code>cout &lt;&lt; endl</code>,
                        we need a <code>attributes_ &lt;&lt; no_attributes_</code> syntax.</para>
                    <para>You can use the flag with the is_flag_active method of a state machine.
                        You can also use the provided helper function is_flag_ (returning a bool)
                        for state and transition behaviors. For example, in the <link
                            xlink:href="examples/iPodEuml.cpp">iPod implementation with eUML</link>,
                        you find the following transition:</para>
                    <programlisting>ForwardPressed == NoForward + EastPressed[!is_flag_(NoFastFwd)]</programlisting>
                    <para>The function also has an optional second parameter which is the state
                        machine on which the function is called. By default, fsm_ is used (the
                        current state machine) but you could provide a functor returning a reference
                        to another state machine.</para>
                    <para>eUML also supports defining deferred events in the state (state machine)
                        definition. To this aim, we can reuse the flag grammar. For example:</para>
                    <programlisting>BOOST_MSM_EUML_STATE((Empty_Entry,Empty_Exit, attributes_ &lt;&lt; no_attributes_,
                      /* deferred */ configure_&lt;&lt; play ),Empty) </programlisting>
                    <para>The configure_ left shift is also responsible for deferring events. Shift
                        inside configure_ a flag and the state will get a flag, shift an event and
                        it will get a deferred event. This replaces the basic front-end
                        definition:</para>
                    <programlisting>typedef mpl::vector&lt;play> deferred_events;</programlisting>
                    <para>In <link xlink:href="examples/OrthogonalDeferredEuml.cpp">this
                            tutorial</link>, player is defining a second orthogonal region with
                        AllOk as initial state. The <code>Empty</code> and <code>Open</code> states
                        also defer the event <code>play</code>. <code>Open</code>,
                            <code>Stopped</code> and <code>Pause</code> also support the flag
                            <code>CDLoaded</code> using the same left shift into
                            <code>configure_</code>.</para>
                    <para>In the functor front-end, we also had the possibility to defer an event
                        inside a transition, which makes possible conditional deferring. This is
                        also possible with eUML through the use of the defer_ order, as shown in
                            <link xlink:href="examples/OrthogonalDeferredEuml.cpp">this
                            tutorial</link>. You will find the following transition:</para>
                    <programlisting>Open + play / defer_</programlisting>
                    <para>This is an <command xlink:href="#eUML-internal">internal
                            transition</command>. Ignore it for the moment. Interesting is, that
                        when the event <code>play</code> is fired and <code>Open</code> is active,
                        the event will be deferred. Now add a guard and you can conditionally defer
                        the event, for example:</para>
                    <programlisting>Open + play [ some_condition ] / defer_</programlisting>
                    <para>This is similar to what we did with the functor front-end. This means that
                        we have the same constraints. Using defer_ instead of a state declaration,
                        we need to tell MSM that we have deferred events in this state machine. We
                        do this (again) using a configure_ declaration in the state machine
                        definition in which we shift the deferred_events configuration flag:</para>
                    <programlisting>BOOST_MSM_EUML_DECLARE_STATE_MACHINE((transition_table,
                                      init_ &lt;&lt; Empty &lt;&lt; AllOk,
                                      Entry_Action, 
                                      Exit_Action, 
                                      attributes_ &lt;&lt; no_attributes_,
                                      configure_&lt;&lt; deferred_events ),
                                    player_)</programlisting>
                    <para>A <link xlink:href="examples/OrthogonalDeferredEuml2.cpp">tutorial</link>
                        illustrates this possibility.</para>
                </sect2>
                <sect2>
                    <title>
                        <command xml:id="eUML-Configuration"/>Customizing a state machine / Getting
                        more speed</title>
                    <para>We just saw how to use configure_ to define deferred events or flags. We
                        can also use it to configure our state machine like we did with the other front-ends:<itemizedlist>
                            <listitem>
                                <para><code>configure_ &lt;&lt; no_exception</code>: disables
                                    exception handling</para>
                            </listitem>
                            <listitem>
                                <para><code>configure_ &lt;&lt; no_msg_queue</code> deactivates the
                                    message queue</para>
                            </listitem>
                            <listitem>
                                <para><code>configure_ &lt;&lt; deferred_events</code> manually
                                    enables event deferring</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>Deactivating the first two features and not activating the third if not
                        needed greatly improves the event dispatching speed of your state machine.
                        Our <link xlink:href="examples/EumlSimple.cpp">speed testing</link> example
                        with eUML does this for the best performance.</para>
                    <para><emphasis role="underline">Important note</emphasis>: As exit pseudo
                        states are using the message queue to forward events out of a submachine,
                        the <code>no_message_queue</code> option cannot be used with state machines
                        containing an exit pseudo state.</para>
                </sect2>
                <sect2>
                    <title>Completion / Anonymous transitions</title>
                    <para>Anonymous transitions (See <command xlink:href="#uml-anonymous">UML
                            tutorial</command>) are transitions without a named event, which are
                        therefore triggered immediately when the source state becomes active,
                        provided a guard allows it. As there is no event, to define such a
                        transition, simply omit the “+” part of the transition (the event), for
                        example: </para>
                    <programlisting>State3 == State4 [always_true] / State3ToState4
State4 [always_true] / State3ToState4 == State3</programlisting>
                    <para>Please have a look at <link
                            xlink:href="examples/AnonymousTutorialEuml.cpp">this example</link>,
                        which implements the <command xlink:href="#anonymous-transitions">previously
                            defined</command> state machine with eUML.</para>
                </sect2>
                <sect2>
                    <title><command xml:id="eUML-internal"/>Internal transitions</title>
                    <para>Like both other front-ends, eUML supports two ways of defining internal transitions:<itemizedlist>
                            <listitem>
                                <para>in the state machine's transition table. In this case, you
                                    need to specify a source state, event, actions and guards but no
                                    target state, which eUML will interpret as an internal
                                    transition, for example this defines a transition internal to
                                    Open, on the event open_close:</para>
                                <programlisting>Open + open_close [internal_guard1] / internal_action1</programlisting>
                                <para><link xlink:href="examples/EumlInternal.cpp">A full
                                        example</link> is also provided.</para>
                            </listitem>
                            <listitem>
                                <para>in a state's <code>internal_transition_table</code>. For
                                    example:</para>
                                <programlisting>BOOST_MSM_EUML_DECLARE_STATE((Open_Entry,Open_Exit),Open_def)
struct Open_impl : public Open_def
{
   BOOST_MSM_EUML_DECLARE_INTERNAL_TRANSITION_TABLE((
        open_close [internal_guard1] / internal_action1
   ))
};</programlisting>
                                <para>Notice how we do not need to repeat that the transition
                                    originates from Open as we already are in Open's context. </para>
                                <para>The <link xlink:href="examples/EumlInternalDistributed.cpp"
                                        >implementation</link> also shows the added bonus offered
                                    for submachines, which can have both the standard
                                    transition_table and an internal_transition_table (which has
                                    higher priority). This makes it easier if you decide to make a
                                    full submachine from a state. It is also slightly faster than
                                    the standard alternative, adding orthogonal regions, because
                                    event dispatching will, if accepted by the internal table, not
                                    continue to the subregions. This gives you a O(1) dispatch
                                    instead of O(number of regions).</para>
                            </listitem>
                        </itemizedlist></para>
                </sect2>
                <sect2>
                    <title>Other state types</title>
                    <para>We saw the <command xlink:href="#eUML-build-state">build_state</command>
                        function, which creates a simple state. Likewise, eUML provides other
                        state-building macros for other types of states:<itemizedlist>
                            <listitem>
                                <para>BOOST_MSM_EUML_TERMINATE_STATE takes the same arguments as
                                    BOOST_MSM_EUML_STATE and defines, well, a terminate
                                    state.</para>
                            </listitem>
                            <listitem>
                                <para>BOOST_MSM_EUML_INTERRUPT_STATE takes the same arguments as
                                    BOOST_MSM_EUML_STATE and defines an interrupt state. However,
                                    the expression argument must contain as first element the event
                                    ending the interruption, for example:
                                        <code>BOOST_MSM_EUML_INTERRUPT_STATE(( end_error /*end
                                        interrupt event*/,ErrorMode_Entry,ErrorMode_Exit
                                        ),ErrorMode)</code></para>
                            </listitem>
                            <listitem>
                                <para>BOOST_MSM_EUML_EXIT_STATE takes the same arguments as
                                    BOOST_MSM_EUML_STATE and defines an exit pseudo state. However,
                                    the expression argument must contain as first element the event
                                    propagated from the exit point:
                                        <code>BOOST_MSM_EUML_EXIT_STATE(( event6 /*propagated
                                        event*/,PseudoExit1_Entry,PseudoExit1_Exit
                                        ),PseudoExit1)</code></para>
                            </listitem>
                            <listitem>
                                <para>BOOST_MSM_EUML_EXPLICIT_ENTRY_STATE defines an entry pseudo
                                    state. It takes 3 parameters: the region index to be entered is
                                    defined as an int argument, followed by the configuration
                                    expression like BOOST_MSM_EUML_STATE and the state name, so that
                                        <code>BOOST_MSM_EUML_EXPLICIT_ENTRY_STATE(0 /*region
                                        index*/,( SubState2_Entry,SubState2_Exit ),SubState2)</code>
                                    defines an entry state into the first region of a
                                    submachine.</para>
                            </listitem>
                            <listitem>
                                <para>BOOST_MSM_EUML_ENTRY_STATE defines an entry pseudo state. It
                                    takes 3 parameters: the region index to be entered is defined as
                                    an int argument, followed by the configuration expression like
                                    BOOST_MSM_EUML_STATE and the state name, so that
                                        <code>BOOST_MSM_EUML_ENTRY_STATE(0,(
                                        PseudoEntry1_Entry,PseudoEntry1_Exit ),PseudoEntry1)</code>
                                    defines a pseudo entry state into the first region of a
                                    submachine.</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>To use these states in the transition table, eUML offers the functions
                            <code>explicit_</code>, <code>exit_pt_</code> and
                        <code>entry_pt_</code>. For example, a direct entry into the substate
                        SubState2 from SubFsm2 could be:</para>
                    <programlisting>explicit_(SubFsm2,SubState2) == State1 + event2</programlisting>
                    <para>Forks being a list on direct entries, eUML supports a logical syntax
                        (state1, state2, ...), for example:</para>
                    <programlisting>(explicit_(SubFsm2,SubState2), 
 explicit_(SubFsm2,SubState2b),
 explicit_(SubFsm2,SubState2c)) == State1 + event3 </programlisting>
                    <para>An entry point is entered using the same syntax as explicit entries:
                        <programlisting>entry_pt_(SubFsm2,PseudoEntry1) == State1 + event4</programlisting></para>
                    <para>For exit points, it is again the same syntax except that exit points are
                        used as source of the transition:
                        <programlisting>State2 == exit_pt_(SubFsm2,PseudoExit1) + event6 </programlisting></para>
                    <para>The <link xlink:href="examples/DirectEntryEuml.cpp">entry tutorial</link>
                        is also available with eUML.</para>
                </sect2>
                <sect2>
                    <title>Helper functions</title>
                    <para>We saw a few helpers but there are more, so let us have a more complete description:<itemizedlist>
                            <listitem>
                                <para>event_ : used inside any action, the event triggering the
                                    transition</para>
                            </listitem>
                            <listitem>
                                <para>state_: used inside entry and exit actions, the entered /
                                    exited state</para>
                            </listitem>
                            <listitem>
                                <para>source_: used inside a transition action, the source
                                    state</para>
                            </listitem>
                            <listitem>
                                <para>target_: used inside a transition action, the target
                                    state</para>
                            </listitem>
                            <listitem>
                                <para>fsm_: used inside any action, the (deepest-level) state
                                    machine processing the transition</para>
                            </listitem>
                            <listitem>
                                <para>These objects can also be used as a function and return an
                                    attribute, for example event_(cd_name)</para>
                            </listitem>
                            <listitem>
                                <para>Int_&lt;int value>: a functor representing an int</para>
                            </listitem>
                            <listitem>
                                <para>Char_&lt;value>: a functor representing a char</para>
                            </listitem>
                            <listitem>
                                <para>Size_t_&lt;value>: a functor representing a size_t</para>
                            </listitem>
                            <listitem>
                                <para>True_ and False_ functors returning true and false
                                    respectively</para>
                            </listitem>
                            <listitem>
                                <para>String_&lt;mpl::string> (boost >= 1.40): a functor
                                    representing a string.</para>
                            </listitem>
                            <listitem>
                                <para>if_then_else_(guard, action, action) where action can be an
                                    action sequence</para>
                            </listitem>
                            <listitem>
                                <para>if_then_(guard, action) where action can be an action
                                    sequence</para>
                            </listitem>
                            <listitem>
                                <para>while_(guard, action) where action can be an action
                                    sequence</para>
                            </listitem>
                            <listitem>
                                <para>do_while_(guard, action) where action can be an action
                                    sequence</para>
                            </listitem>
                            <listitem>
                                <para>for_(action, guard, action, action) where action can be an
                                    action sequence</para>
                            </listitem>
                            <listitem>
                                <para>process_(some_event [, some state machine] [, some state
                                    machine] [, some state machine] [, some state machine]) will
                                    call process_event (some_event) on the current state machine or
                                    on the one(s) passed as 2nd , 3rd, 4th, 5th argument. This allow
                                    sending events to several external machines</para>
                            </listitem>
                            <listitem>
                                <para>process2_(some_event,Value [, some state machine] [, some
                                    state machine] [, some state machine]) will call process_event
                                    (some_event(Value)) on the current state machine or on the
                                    one(s) passed as 3rd, 4th, 5th argument</para>
                            </listitem>
                            <listitem>
                                <para>is_ flag_(some_flag[, some state machine]) will call
                                    is_flag_active on the current state machine or on the one passed
                                    as 2nd argument</para>
                            </listitem>
                            <listitem>
                                <para>Predicate_&lt;some predicate>: Used in STL algorithms. Wraps
                                    unary/binary functions to make them eUML-compatible so that they
                                    can be used in STL algorithms</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>This can be quite fun. For example, </para>
                    <programlisting>/( if_then_else_(--fsm_(m_SongIndex) > Int_&lt;0>(),/*if clause*/
                 show_playing_song, /*then clause*/
                 (fsm_(m_SongIndex)=Int_&lt;1>(),process_(EndPlay))/*else clause*/
                 ) 
  )</programlisting>
                    <para>means: if (fsm.SongIndex > 0, call show_playing_song else
                        {fsm.SongIndex=1; process EndPlay on fsm;}</para>
                    <para>A few examples are using these features:<itemizedlist>
                            <listitem>
                                <para>the iPod example introduced at the BoostCon09 <link
                                        xlink:href="examples/iPodEuml.cpp">has been rewritten</link>
                                    with eUML (weak compilers please move on...)</para>
                            </listitem>
                            <listitem>
                                <para>the iPodSearch example also introduced at the BoostCon09 <link
                                        xlink:href="examples/iPodSearchEuml.cpp">has been
                                        rewritten</link> with eUML. In this example, you will also
                                    find some examples of STL functor usage.</para>
                            </listitem>
                            <listitem>
                                <para><link xlink:href="examples/SimpleTimer.cpp">A simpler
                                        timer</link> example is a good starting point. </para>
                            </listitem>
                        </itemizedlist></para>
                    <para>There is unfortunately a small catch. Defining a functor using
                        MSM_EUML_METHOD or MSM_EUML_FUNCTION will create a correct functor. Your own
                        eUML functors written as described at the beginning of this section will
                        also work well, <emphasis role="underline">except</emphasis>, for the
                        moment, with the while_, if_then_, if_then_else_ functions.</para>
                </sect2>
                <sect2>
                    <title>Phoenix-like STL support</title>
                    <para>eUML supports most C++ operators (except address-of). For example it is
                        possible to write event_(some_attribute)++ or [source_(some_bool) &amp;&amp;
                        fsm_(some_other_bool)]. But a programmer needs more than operators in his
                        daily programming. The STL is clearly a must have. Therefore, eUML comes in
                        with a lot of functors to further reduce the need for your own functors for
                        the transition table. For almost every algorithm or container method of the
                        STL, a corresponding eUML function is defined. Like Boost.Phoenix, “.” And
                        “->” of call on objects are replaced by a functional programming paradigm,
                        for example:<itemizedlist>
                            <listitem>
                                <para>begin_(container), end_(container): return iterators of a
                                    container.</para>
                            </listitem>
                            <listitem>
                                <para>empty_(container): returns container.empty()</para>
                            </listitem>
                            <listitem>
                                <para>clear_(container): container.clear()</para>
                            </listitem>
                            <listitem>
                                <para>transform_ : std::transform</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>In a nutshell, almost every STL method or algorithm is matched by a
                        corresponding functor, which can then be used in the transition table or
                        state actions. The <link xlink:href="#Reference-begin">reference</link>
                        lists all eUML functions and the underlying functor (so that this
                        possibility is not reserved to eUML but also to the functor-based
                        front-end). The file structure of this Phoenix-like library matches the one
                        of Boost.Phoenix. All functors for STL algorithms are to be found in:</para>
                    <programlisting>#include &lt;msm/front/euml/algorithm.hpp></programlisting>
                    <para>The algorithms are also divided into sub-headers, matching the phoenix
                        structure for simplicity:</para>
                    <programlisting>#include &lt; msm/front/euml/iteration.hpp> 
#include &lt; msm/front/euml/transformation.hpp>
#include &lt; msm/front/euml/querying.hpp> </programlisting>
                    <para>Container methods can be found in:</para>
                    <programlisting>#include &lt; msm/front/euml/container.hpp></programlisting>
                    <para>Or one can simply include the whole STL support (you will also need to
                        include euml.hpp):</para>
                    <programlisting>#include &lt; msm/front/euml/stl.hpp></programlisting>
                    <para>A few examples (to be found in <link
                            xlink:href="examples/iPodSearchEuml.cpp">this tutorial</link>):<itemizedlist>
                            <listitem>
                                <para><code>push_back_(fsm_(m_tgt_container),event_(m_song))</code>:
                                    the state machine has an attribute m_tgt_container of type
                                    std::vector&lt;OneSong> and the event has an attribute m_song of
                                    type OneSong. The line therefore pushes m_song at the end of
                                    m_tgt_container</para>
                            </listitem>
                            <listitem>
                                <para><code>if_then_( state_(m_src_it) !=
                                        end_(fsm_(m_src_container)),
                                        process2_(OneSong(),*(state_(m_src_it)++)) )</code>: the
                                    current state has an attribute m_src_it (an iterator). If this
                                    iterator != fsm.m_src_container.end(), process OneSong on fsm,
                                    copy-constructed from state.m_src_it which we
                                    post-increment</para>
                            </listitem>
                        </itemizedlist></para>
                </sect2>
                <sect2>
                    <title><command xml:id="eUML-phoenix"/>Writing actions with Boost.Phoenix (in development)</title>
                    <para> It is also possible to write actions, guards, state entry and exit
                        actions using a reduced set of Boost.Phoenix capabilities. This feature
                        is still in development stage, so you might get here and there some
                        surprise. Simple cases, however, should work well. What will not work
                        will be mixing of eUML and Phoenix functors. Writing guards in one
                        language and actions in another is ok though.</para>
                    <para>Phoenix also supports a larger syntax than what will ever be possible
                        with eUML, so you can only use a reduced set of phoenix's grammar. This
                        is due to the nature of eUML. The run-time transition table definition
                        is translated to a type using Boost.Typeof. The result is a "normal" MSM
                        transition table made of functor types. As C++ does not allow mixing
                        run-time and compile-time constructs, there will be some limit (trying
                        to instantiate a template class MyTemplateClass&lt;i> where i is an int
                        will give you an idea). This means following valid Phoenix constructs
                        will not work:</para>
                    <para>
                        <itemizedlist>
                            <listitem>
                                <para>literals</para>
                            </listitem>
                            <listitem>
                                <para>function pointers</para>
                            </listitem>
                            <listitem>
                                <para>bind</para>
                            </listitem>
                            <listitem>
                                <para>->*</para>
                            </listitem>
                        </itemizedlist>
                    </para>
                    <para>MSM also provides placeholders which make more sense in its context
                        than arg1.. argn:</para>
                    <para>
                        <itemizedlist>
                            <listitem>
                                <para>_event: the event triggering the transition</para>
                            </listitem>
                            <listitem>
                                <para>_fsm: the state machine processing the event</para>
                            </listitem>
                            <listitem>
                                <para>_source: the source state of the transition</para>
                            </listitem>
                            <listitem>
                                <para>_target: the target state of the transition</para>
                            </listitem>
                            <listitem>
                                <para>_state: for state entry/exit actions, the entry/exit
                                    state</para>
                            </listitem>
                        </itemizedlist>
                    </para>
                    <para>Future versions of MSM will support Phoenix better. You can contribute
                        by finding out cases which do not work but should, so that they can be
                        added.</para>
                    <para>Phoenix support is not activated by default. To activate it, add
                        before any MSM header: #define BOOST_MSM_EUML_PHOENIX_SUPPORT.</para>
                    <para>A <link
                        xlink:href="examples/SimplePhoenix.cpp">simple example</link> shows some basic capabilities.</para>
                </sect2>
            </sect1>
            <sect1>
                <title>Back-end</title>
                <para>There is, at the moment, one back-end. This back-end contains the library
                    engine and defines the performance and functionality trade-offs. The currently
                    available back-end implements most of the functionality defined by the UML 2.0
                    standard at very high runtime speed, in exchange for longer compile-time. The
                    runtime speed is due to a constant-time double-dispatch and self-adapting
                    capabilities allowing the framework to adapt itself to the features used by a
                    given concrete state machine. All unneeded features either disable themselves or
                    can be manually disabled. See section 5.1 for a complete description of the
                    run-to-completion algorithm.</para>
                <sect2>
                    <title>Creation </title>
                    <para>MSM being divided between front and back-end, one needs to first define a
                        front-end. Then, to create a real state machine, the back-end must be
                        declared:
                        <programlisting>typedef msm::back::state_machine&lt;my_front_end> my_fsm;</programlisting></para>
                    <para>We now have a fully functional state machine type. The next sections will
                        describe what can be done with it.</para>
                </sect2>
                <sect2>
                    <title><command xml:id="backend-start"/>Starting and stopping a state
                        machine</title>
                    <para>The <code>start()</code> method starts the state machine, meaning it will
                        activate the initial state, which means in turn that the initial state's
                        entry behavior will be called. We need the start method because you do not
                        always want the entry behavior of the initial state to be called immediately
                        but only when your state machine is ready to process events. A good example
                        of this is when you use a state machine to write an algorithm and each loop
                        back to the initial state is an algorithm call. Each call to start will make
                        the algorithm run once. The <link xlink:href="examples/iPodSearch.cpp"
                            >iPodSearch</link> example uses this possibility.</para>
                    <para>The <code>stop()</code> method works the same way. It will cause the exit
                        actions of the currently active states(s) to be called.</para>
                    <para>Both methods are actually not an absolute need. Not calling them will
                        simply cause your first entry or your last exit action not to be
                        called.</para>
                </sect2>
                <sect2>
                    <title>Event dispatching</title>
                    <para>The main reason to exist for a state machine is to dispatch events. For
                        MSM, events are objects of a given event type. The object itself can contain
                        data, but the event type is what decides of the transition to be taken. For
                        MSM, if some_event is a given type (a simple struct for example) and e1 and
                        e2 concrete instances of some_event, e1 and e2 are equivalent, from a
                        transition perspective. Of course, e1 and e2 can have different values and
                        you can use them inside actions. Events are dispatched as const reference,
                        so actions cannot modify events for obvious side-effect reasons. To dispatch
                        an event of type some_event, you can simply create one on the fly or
                        instantiate if before processing: </para>
                    <programlisting>my_fsm fsm; fsm.process_event(some_event());
some_event e1; fsm.process_event(e1)</programlisting>
                    <para>Creating an event on the fly will be optimized by the compiler so the
                        performance will not degrade.</para>
                </sect2>
                <sect2>
                    <title>Active state(s)</title>
                    <para>The backend also offers a way to know which state is active, though you
                        will normally only need this for debugging purposes. If what you need simply
                        is doing something with the active state, <command
                            xlink:href="#UML-internal-transition">internal transitions</command> or
                            <command xlink:href="#backend-visitor">visitors</command> are a better
                        alternative. If you need to know what state is active, const int*
                        current_state() will return an array of state ids. Please refer to the
                            <command xlink:href="#internals-state-id">internals section</command> to
                        know how state ids are generated.</para>
                </sect2>
                <sect2>
                    <title><command xml:id="back-end-serialization"/>Serialization</title>
                    <para>A common need is the ability to save a state machine and restore it at a
                        different time. MSM supports this feature for the basic and functor
                        front-ends, and in a more limited manner for eUML. MSM supports
                        boost::serialization out of the box (by offering a <code>serialize</code>
                        function). Actually, for basic serialization, you need not do much, a MSM
                        state machine is serializable almost like any other type. Without any
                        special work, you can make a state machine remember its state, for
                        example:</para>
                    <para>
                        <programlisting>MyFsm fsm;
// write to archive
std::ofstream ofs("fsm.txt");
// save fsm to archive
{
    boost::archive::text_oarchive oa(ofs);
    // write class instance to archive
    oa &lt;&lt; fsm;
}                                                  </programlisting>
                    </para>
                    <para>Loading back is very similar:</para>
                    <para>
                        <programlisting>MyFsm fsm;
{
    // create and open an archive for input
    std::ifstream ifs("fsm.txt");
    boost::archive::text_iarchive ia(ifs);
    // read class state from archive
    ia >> fsm;
}                                          </programlisting>
                    </para>
                    <para>This will (de)serialize the state machine itself but not the concrete
                        states' data. This can be done on a per-state basis to reduce the amount of
                        typing necessary. To allow serialization of a concrete state, provide a
                        do_serialize typedef and implement the serialize function:</para>
                    <para>
                        <programlisting>struct Empty : public msm::front::state&lt;> 
{
    // we want Empty to be serialized. First provide the typedef
    typedef int do_serialize;
    // then implement serialize
    template&lt;class Archive>
    void serialize(Archive &amp; ar, const unsigned int /* version */)
    {
        ar &amp; some_dummy_data;
    }
    Empty():some_dummy_data(0){}           
    int some_dummy_data;
};                        </programlisting>
                    </para>
                    <para>You can also serialize data contained in the front-end class. Again, you
                        need to provide the typedef and implement serialize:</para>
                    <para>
                        <programlisting>struct player_ : public msm::front::state_machine_def&lt;player_>
{
    //we might want to serialize some data contained by the front-end
    int front_end_data;
    player_():front_end_data(0){}
    // to achieve this, provide the typedef
    typedef int do_serialize;
    // and implement serialize
    template&lt;class Archive>
    void serialize(Archive &amp; ar, const unsigned int )
    {
        ar &amp; front_end_data;
    }  
...
};                                               </programlisting>
                    </para>
                    <para>The saving of the back-end data (the current state(s)) is valid for all
                        front-ends, so a front-end written using eUML can be serialized. However, to
                        serialize a concrete state, the macros like
                            <code>BOOST_MSM_EUML_STATE</code> cannot be used, so the state will have
                        to be implemented by directly inheriting from
                            <code>front::euml::euml_state</code>.</para>
                    <para>The only limitiation is that the event queues cannot be serialized so
                        serializing must be done in a stable state, when no event is being
                        processed. You can serialize during event processing only if using no queue
                        (deferred or event queue).</para>
                    <para>This <link
                        xlink:href="examples/Serialize.cpp">example</link> shows a state machine which we serialize after processing an
                        event. The <code>Empty</code> state also has some data to serialize.</para>
                </sect2>
                <sect2>
                    <title><command xml:id="backend-base-state"/>Base state type </title>
                    <para>Sometimes, one needs to customize states to avoid repetition and provide a
                        common functionality, for example in the form of a virtual method. You might
                        also want to make your states polymorphic so that you can call typeid on
                        them for logging or debugging. It is also useful if you need a visitor, like
                        the next section will show. You will notice that all front-ends offer the
                        possibility of adding a base type. Note that all states and state machines
                        must have the same base state, so this could reduce reuse. For example,
                        using the basic front end, you need to:<itemizedlist>
                            <listitem>
                                <para>Add the non-default base state in your msm::front::state&lt;>
                                    definition, as first template argument (except for
                                    interrupt_states for which it is the second argument, the first
                                    one being the event ending the interrupt), for example,
                                    my_base_state being your new base state for all states in a
                                    given state machine:
                                    <programlisting>struct Empty : public msm::front::state&lt;my_base_state></programlisting>
                                    Now, my_base_state is your new base state. If it has a virtual
                                    function, your states become polymorphic. MSM also provides a
                                    default polymorphic base type,
                                        <code>msm::front::polymorphic_state</code>
                                </para>
                            </listitem>
                            <listitem>
                                <para>Add the user-defined base state in the state machine frontend
                                    definition, as a second template argument, for example:
                                    <programlisting>struct player_ : public msm::front::state_machine&lt;player_,my_base_state>             </programlisting></para>
                            </listitem>
                        </itemizedlist></para>
                    <para>You can also ask for a state with a given id (which you might have gotten
                        from current_state()) using <code>const base_state* get_state_by_id(int id)
                            const</code> where base_state is the one you just defined. You can now
                        do something polymorphically.</para>
                </sect2>
                <sect2>
                    <title><command xml:id="backend-visitor"/>Visitor</title>
                    <para>In some cases, having a pointer-to-base of the currently active states is
                        not enough. You might want to call non-virtually a method of the currently
                        active states. It will not be said that MSM forces the virtual keyword down
                        your throat!</para>
                    <para>To achieve this goal, MSM provides its own variation of a visitor pattern
                        using the previously described user-defined state technique. If you add to
                        your user-defined base state an <code>accept_sig</code> typedef giving the
                        return value (unused for the moment) and parameters and provide an accept
                        method with this signature, calling visit_current_states will cause accept
                        to be called on the currently active states. Typically, you will also want
                        to provide an empty default accept in your base state in order in order not
                        to force all your states to implement accept. For example your base state
                        could be:</para>
                    <programlisting>struct my_visitable_state
{
   // signature of the accept function
   typedef args&lt;void> accept_sig;
   // we also want polymorphic states
   virtual ~my_visitable_state() {}
   // default implementation for states who do not need to be visited
   void accept() const {}
};</programlisting>
                    <para>This makes your states polymorphic and visitable. In this case, accept is
                        made const and takes no argument. It could also be:</para>
                    <programlisting>struct SomeVisitor {…};
struct my_visitable_state
{
    // signature of the accept function
    typedef args&lt;void,SomeVisitor&amp;> accept_sig;
    // we also want polymorphic states
    virtual ~my_visitable_state() {}
    // default implementation for states who do not need to be visited
    void accept(SomeVisitor&amp;) const {}
};</programlisting>
                    <para>And now, <code>accept</code> will take one argument (it could also be
                        non-const). By default, <code>accept</code> takes up to 2 arguments. To get
                        more, set #define BOOST_MSM_VISITOR_ARG_SIZE to another value before
                        including state_machine.hpp. For example:</para>
                    <programlisting>#define BOOST_MSM_VISITOR_ARG_SIZE 3
#include &lt;boost/msm/back/state_machine.hpp></programlisting>
                    <para>Note that accept will be called on ALL active states <emphasis
                            role="underline">and also automatically on sub-states of a
                            submachine</emphasis>.</para>
                    <para><emphasis role="underline">Important warning</emphasis>: The method
                        visit_current_states takes its parameter by value, so if the signature of
                        the accept function is to contain a parameter passed by reference, pass this
                        parameter with a boost:ref/cref to avoid undesired copies or slicing. So,
                        for example, in the above case, call:</para>
                    <programlisting>SomeVisitor vis; sm.visit_current_states(boost::ref(vis));</programlisting>
                    <para>This <link xlink:href="examples/SM-2Arg.cpp">example</link> uses a
                        visiting function with 2 arguments.</para>
                </sect2>
                <sect2>
                    <title>Flags</title>
                    <para>Flags is a MSM-only concept, supported by all front-ends, which base
                        themselves on the functions: </para>
                    <programlisting>template &lt;class Flag> bool is_flag_active()
template &lt;class Flag,class BinaryOp> bool is_flag_active()</programlisting>
                    <para>These functions return true if the currently active state(s) support the
                        Flag property. The first variant ORs the result if there are several
                        orthogonal regions, the second one expects OR or AND, for example:</para>
                    <programlisting>my_fsm.is_flag_active&lt;MyFlag>()
my_fsm.is_flag_active&lt;MyFlag,my_fsm_type::Flag_OR>()</programlisting>
                    <para>Please refer to the front-ends sections for usage examples.</para>
                </sect2>
                <sect2>
                    <title>Getting a state</title>
                    <para>It is sometimes necessary to have the client code get access to the
                        states' data. After all, the states are created once for good and hang
                        around as long as the state machine does so why not use it? You simply just
                        need sometimes to get information about any state, even inactive ones. An
                        example is if you want to write a coverage tool and know how many times a
                        state was visited. To get a state, use the get_state method giving the state
                        name, for example: </para>
                    <programlisting>player::Stopped* tempstate = p.get_state&lt;player::Stopped*>();</programlisting>
                    <para> or </para>
                    <programlisting>player::Stopped&amp; tempstate2 = p.get_state&lt;player::Stopped&amp;>();</programlisting>
                    <para>depending on your personal taste. </para>
                </sect2>
                <sect2>
                    <title><command xml:id="backend-fsm-constructor-args"/> State machine constructor with arguments </title>
                    <para>You might want to define a state machine with a non-default constructor.
                        For example, you might want to write: </para>
                    <programlisting>struct player_ : public msm::front::state_machine_def&lt;player_> 
{ 
    player_(int some_value){…} 
}; </programlisting>
                    <para>This is possible, using the back-end as forwarding object: </para>
                    <programlisting>typedef msm::back::state_machine&lt;player_ > player; player p(3);</programlisting>
                    <para>The back-end will call the corresponding front-end constructor upon
                        creation.</para>
                    <para>You can pass arguments up to the value of the
                        BOOST_MSM_CONSTRUCTOR_ARG_SIZE macro (currently 5) arguments. Change this
                        value before including any header if you need to overwrite the default. </para>
                    <para>You can also pass arguments by reference (or const-reference) using
                        boost::ref (or boost::cref):</para>
                    <programlisting>struct player_ : public msm::front::state_machine_def&lt;player_>  
{
   player_(SomeType&amp; t, int some_value){…}  
}; 

typedef msm::back::state_machine&lt;player_ > player; 
SomeType data;
player p(boost::ref(data),3);
                    </programlisting>
                    <para>Normally, MSM default-constructs all its states or submachines. There are
                        however cases where you might not want this. An example is when you use a
                        state machine as submachine, and this submachine used the above defined
                        constructors. You can add as first argument of the state machine constructor
                        an expression where existing states are passed and copied:</para>
                    <programlisting>player p( back::states_ &lt;&lt; state_1 &lt;&lt; ... &lt;&lt; state_n , boost::ref(data),3);</programlisting>  
                <para>Where state_1..n are instances of some or all of the states of the state
                        machine. Submachines being state machines, this can recurse, for example, if
                        Playing is a submachine containing a state Song1 having itself a constructor
                        where some data is passed:</para>                    
                    <programlisting>player p( back::states_ &lt;&lt; Playing(back::states_ &lt;&lt; Song1(some_Song1_data)) , 
          boost::ref(data),3);</programlisting>
                    <para>It is also possible to replace a given state by a new instance at any time
                        using <code>set_states()</code> and the same syntax, for example:
                        <programlisting>p.set_states( back::states_ &lt;&lt; state_1 &lt;&lt; ... &lt;&lt; state_n );</programlisting></para>
                    <para>An <link xlink:href="examples/Constructor.cpp"
                        >example</link> making intensive use of this capability is provided.</para>
                </sect2>
                <sect2>
                    <title><command xml:id="backend-tradeof-rt-ct"/>Trading run-time speed for
                        better compile-time / multi-TU compilation</title>
                    <para>MSM is optimized for run-time speed at the cost of longer compile-time.
                        This can become a problem with older compilers and big state machines,
                        especially if you don't really care about run-time speed that much and would
                        be satisfied by a performance roughly the same as most state machine
                        libraries. MSM offers a back-end policy to help there. But before you try
                        it, if you are using a VC compiler, deactivate the /Gm compiler option
                        (default for debug builds). This option can cause builds to be 3 times
                        longer... If the compile-time still is a problem, read further. MSM offers a
                        policy which will speed up compiling in two main cases:<itemizedlist>
                            <listitem>
                                <para>many transition conflicts</para>
                            </listitem>
                            <listitem>
                                <para>submachines</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>The back-end <code>msm::back::state_machine</code> has a policy argument
                        (first is the front-end, then the history policy) defaulting to
                            <code>favor_runtime_speed</code>. To switch to
                            <code>favor_compile_time</code>, which is declared in
                            <code>&lt;msm/back/favor_compile_time.hpp></code>, you need to:<itemizedlist>
                            <listitem>
                                <para>switch the policy to <code>favor_compile_time</code> for the
                                    main state machine (and possibly submachines)</para>
                            </listitem>
                            <listitem>
                                <para>move the submachine declarations into their own header which
                                    includes
                                    <code>&lt;msm/back/favor_compile_time.hpp></code></para>
                            </listitem>
                            <listitem>
                                <para>add for each submachine a cpp file including your header and
                                    calling a macro, which generates helper code, for
                                    example:</para>
                                <programlisting>#include "mysubmachine.hpp"
BOOST_MSM_BACK_GENERATE_PROCESS_EVENT(mysubmachine)</programlisting>
                            </listitem>
                            <listitem>
                                <para>configure your compiler for multi-core compilation</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>You will now compile your state machine on as many cores as you have
                        submachines, which will greatly speed up the compilation if you factor your
                        state machine into smaller submachines.</para>
                    <para>Independently, transition conflicts resolution will also be much
                        faster.</para>
                    <para>This policy uses boost.any behind the hood, which means that we will lose
                        one feature which MSM offers with the default policy, <link
                            xlink:href="#event-hierarchy">event hierarchy</link>. The following
                        example takes our iPod example and speeds up compile-time by using this
                        technique. We have:<itemizedlist>
                            <listitem>
                                <para><link xlink:href="examples/iPod_distributed/iPod.cpp">our main
                                        state machine and main function</link></para>
                            </listitem>
                            <listitem>
                                <para><link xlink:href="examples/iPod_distributed/PlayingMode.hpp"
                                        >PlayingMode moved to a separate header</link></para>
                            </listitem>
                            <listitem>
                                <para><link xlink:href="examples/iPod_distributed/PlayingMode.cpp">a
                                        cpp for PlayingMode</link></para>
                            </listitem>
                            <listitem>
                                <para><link xlink:href="examples/iPod_distributed/MenuMode.hpp"
                                        >MenuMode moved to a separate header</link></para>
                            </listitem>
                            <listitem>
                                <para><link xlink:href="examples/iPod_distributed/MenuMode.cpp">a
                                        cpp for MenuMode</link></para>
                            </listitem>
                            <listitem>
                                <para><link xlink:href="examples/iPod_distributed/Events.hpp">events
                                        move to a separate header as all machines use
                                    it</link></para>
                            </listitem>
                        </itemizedlist>
                    </para>
                </sect2>
                <sect2>
                    <title><command xml:id="backend-compile-time-analysis"/>Compile-time state machine analysis </title>
                    <para>A MSM state machine being a metaprogram, it is only logical that cheking
                        for the validity of a concrete state machine happens compile-time. To this
                        aim, using the compile-time graph library <link xlink:href="http://www.dynagraph.org/mpl_graph/">mpl_graph</link> (delivered at the moment
                        with MSM) from Gordon Woodhull, MSM provides several compile-time checks:<itemizedlist>
                            <listitem>
                                <para>Check that orthogonal regions ar truly orthogonal.</para>
                            </listitem>
                            <listitem>
                                <para>Check that all states are either reachable from the initial
                                    states or are explicit entries / pseudo-entry states.</para>
                            </listitem>
                        </itemizedlist></para>
                    <para>To make use of this feature, the back-end provides a policy (default is no
                        analysis), <code>msm::back::mpl_graph_fsm_check</code>. For example:</para>
                    <programlisting> typedef msm::back::state_machine&lt; player_,msm::back::mpl_graph_fsm_check> player;           </programlisting>
                    <para>As MSM is now using Boost.Parameter to declare policies, the policy choice
                        can be made at any position after the front-end type (in this case
                        <code>player_</code>).</para>
                    <para>In case an error is detected, a compile-time assertion is provoked.</para>
                    <para>This feature is not enabled by default because it has a non-neglectable
                        compile-time cost. The algorithm is linear if no explicit or pseudo entry
                        states are found in the state machine, unfortunately still O(number of
                        states * number of entry states) otherwise. This will be improved in future
                        versions of MSM.</para>
                    <para>The same algorithm is also used in case you want to omit providing the
                        region index in the <command xlink:href="#explicit-entry-no-region-id">explicit entry / pseudo entry state</command> declaration.</para>
                    <para>The author's advice is to enable the checks after any state machine
                        structure change and disable it again after sucessful analysis.</para>
                    <para>The <link xlink:href="examples/TestErrorOrthogonality.cpp">following example</link> provokes an assertion if one of the first two lines
                        of the transition table is used.</para>
                </sect2>
                <sect2>
                    <title><command xml:id="backend-enqueueing"/> Enqueueing events for later
                        processing </title>
                    <para>Calling <code>process_event(Event const&amp;)</code> will immediately
                        process the event with run-to-completion semantics. You can also enqueue the
                        events and delay their processing by calling <code>enqueue_event(Event
                            const&amp;)</code> instead. Calling <code>execute_queued_events()</code> will then
                        process all enqueued events (in FIFO order).</para>
                    <para>You can query the queue size by calling <code>get_message_queue_size()</code>.</para>
                </sect2>  
                <sect2>
                    <title><command xml:id="backend-queues"/> Customizing the message queues </title>
                    <para>MSM uses by default a std::deque for its queues (one message queue for
                        events generated during run-to-completion or with
                        <code>enqueue_event</code>, one for deferred events). Unfortunately, on some
                        STL implementations, it is a very expensive container in size and copying
                        time. Should this be a problem, MSM offers an alternative based on
                        boost::circular_buffer. The policy is msm::back::queue_container_circular.
                        To use it, you need to provide it to the back-end definition:</para>
                        <programlisting> typedef msm::back::state_machine&lt; player_,msm::back::queue_container_circular> player;           </programlisting>
                    <para>You can access the queues with get_message_queue and get_deferred_queue,
                        both returning a reference or a const reference to the queues themselves.
                        Boost::circular_buffer is outside of the scope of this documentation. What
                        you will however need to define is the queue capacity (initially is 0) to
                        what you think your queue will at most grow, for example (size 1 is
                        common):</para>
                    <programlisting> fsm.get_message_queue().set_capacity(1);           </programlisting>
                </sect2>                  
                <sect2>
                    <title><command xml:id="backend-boost-parameter"/>Policy definition with Boost.Parameter </title>
                    <para>MSM uses Boost.Parameter to allow easier definition of
                        back::state_machine&lt;> policy arguments (all except the front-end). This
                        allows you to define policy arguments (history, compile-time / run-time,
                        state machine analysis, container for the queues) at any position, in any
                        number. For example: </para> 
                    <programlisting> typedef msm::back::state_machine&lt; player_,msm::back::mpl_graph_fsm_check> player;  
 typedef msm::back::state_machine&lt; player_,msm::back::AlwaysHistory> player;  
 typedef msm::back::state_machine&lt; player_,msm::back::mpl_graph_fsm_check,msm::back::AlwaysHistory> player; 
 typedef msm::back::state_machine&lt; player_,msm::back::AlwaysHistory,msm::back::mpl_graph_fsm_check> player;      </programlisting>                    
                </sect2>   
                <sect2>
                    <title><command xml:id="backend-state-switch"/>Choosing when to switch active
                        states </title>
                    <para>The UML Standard is silent about a very important question: when a
                        transition fires, at which exact point is the target state the new active
                        state of a state machine? At the end of the transition? After the source
                        state has been left? What if an exception is thrown? The Standard considers
                        that run-to-completion means a transition completes in almost no time. But
                        even this can be in some conditions a very very long time. Consider the
                        following example. We have a state machine representing a network
                        connection. We can be <code>Connected</code> and <code>Disconnected</code>. When we move from one
                        state to another, we send a (Boost) Signal to another entity. By default,
                        MSM makes the target state as the new state after the transition is
                        completed. We want to send a signal based on a flag is_connected which is
                        true when in state Connected.</para>
                    <para>We are in state <code>Disconnected</code> and receive an event <code>connect</code>. The transition
                        action will ask the state machine <code>is_flag_active&lt;is_connected></code> and will
                        get... false because we are still in <code>Disconnected</code>. Hmm, what to do? We could
                        queue the action and execute it later, but it means an extra queue, more
                        work and higher run-time.</para>
                    <para>MSM provides the possibility (in form of a policy) for a front-end to
                        decide when the target state becomes active. It can be:<itemizedlist>
                            <listitem>
                                <para>before the transition fires, if the guard will allow the
                                    transition to fire:
                                        <code>active_state_switch_before_transition</code></para>
                            </listitem>
                            <listitem>
                                <para>after calling the exit action of the source state:
                                        <code>active_state_switch_after_exit</code></para>
                            </listitem>
                            <listitem>
                                <para>after the transition action is executed:
                                        <code>active_state_switch_after_transition_action</code></para>
                            </listitem>
                            <listitem>
                                <para>after the entry action of the target state is executed
                                    (default): <code>active_state_switch_after_entry</code></para>
                            </listitem>
                        </itemizedlist>The problem and the solution is shown for the
                        <link xlink:href="examples/ActiveStateSetBeforeTransition.cpp">functor-front-end</link> 
                        and <link xlink:href="examples/ActivateStateBeforeTransitionEuml.cpp">eUML</link>. Removing <code>active_state_switch_before_transition</code>
                        will show the default state.   </para>                    
                </sect2>                   
            </sect1>
        </chapter>
        <chapter>
            <title> Performance / Compilers</title>
            <para>Tests were made on different PCs running Windows XP and Vista and compiled with
                VC9 SP1 or Ubuntu and compiled with g++ 4.2 and 4.3. For these tests, the same
                player state machine was written using Boost.Statechart, as a <link
                    xlink:href="examples/SCSimple.cpp">state machine with only simple states</link>
                and as a <link xlink:href="examples/SCComposite.cpp">state machine with a composite
                    state</link>. The same simple and composite state machines are implemented with
                MSM with a standard frontend <link xlink:href="examples/MsmSimple.cpp"
                    >(simple)</link><link xlink:href="examples/MsmComposite.cpp">(composite)</link>,
                the simple one also with <link xlink:href="examples/MsmSimpleFunctors.cpp"
                    >functors</link> and with <link xlink:href="examples/EumlSimple.cpp"
                >eUML</link>. As these simple machines need no terminate/interrupt states, no
                message queue and have no-throw guarantee on their actions, the MSM state machines
                are defined with minimum functionality. Test machine is a Q6600 2.4GHz, Vista
                64.</para>
            <sect1>
                <title>Speed</title>
                <para>VC9:<itemizedlist>
                        <listitem>
                            <para>The simple test completes 90 times faster with MSM than with
                                Boost.Statechart</para>
                        </listitem>
                        <listitem>
                            <para>The composite test completes 25 times faster with MSM</para>
                        </listitem>
                    </itemizedlist></para>
                <para>gcc 4.2.3 (Ubuntu 8.04 in VMWare, same PC):<itemizedlist>
                        <listitem>
                            <para>The simple test completes 46 times faster with MSM</para>
                        </listitem>
                        <listitem>
                            <para>The composite test completes 19 times faster with Msm</para>
                        </listitem>
                    </itemizedlist></para>
            </sect1>
            <sect1>
                <title>Executable size</title>
                <para>There are some worries that MSM generates huge code. Is it true? The 2
                    compilers I tested disagree with this claim. On VC9, the test state machines
                    used in the performance section produce executables of 14kB (for simple and
                    eUML) and 21kB (for the composite). This includes the test code and iostreams.
                    By comparison, an empty executable with iostreams generated by VC9 has a size of
                    7kB. Boost.Statechart generates executables of 43kB and 54kB. As a bonus, eUML
                    comes for “free” in terms of executable size. You even get a speed gain. With
                    g++ 4.3, it strongly depends on the compiler options (much more than VC). A good
                    size state machine with –O3 can generate an executable of 600kB, and with eUML
                    you can get to 1.5MB. Trying with –Os –s I come down to 18kB and 30kB for the
                    test state machines, while eUML will go down to 1MB (which is still big), so in
                    this case eUML does not come for free.</para>
            </sect1>
            <sect1>
                <title>Supported compilers</title>
                <para>For a current status, have a look at the <link
                        xlink:href="http://www.boost.org/development/tests/trunk/developer/msm.html"
                        >regression tests</link>.</para>
                <para>MSM was successfully tested with: <itemizedlist>
                        <listitem>
                            <para>VC8 (partly), VC9, VC10</para>
                        </listitem>
                        <listitem>
                            <para>g++ 4.0.1 and higher</para>
                        </listitem>
                        <listitem>
                            <para>Intel 10.1 and higher</para>
                        </listitem>
                        <listitem>
                            <para>Clang 2.9</para>
                        </listitem>
                        <listitem>
                            <para>Green Hills Software MULTI for ARM v5.0.5 patch 4416 (Simple and
                                Composite tutorials)</para>
                        </listitem>
                        <listitem>
                            <para>Partial support for IBM compiler</para>
                        </listitem>
                    </itemizedlist></para>
                <para>VC8 and to some lesser extent VC9 suffer from a bug. Enabling the option
                    "Enable Minimal Rebuild" (/Gm) will cause much higher compile-time (up to three
                    times with VC8!). This option being activated per default in Debug mode, this
                    can be a big problem.</para>
            </sect1>
            <sect1>
                <title> Limitations </title>
                <para>
                    <itemizedlist>
                        <listitem>
                            <para>Compilation times of state machines with > 80 transitions that are
                                going to make you storm the CFO's office and make sure you get a
                                shiny octocore with 12GB RAM by next week, unless he's interested in
                                paying you watch the compiler agonize for hours... (Make sure you
                                ask for dual 24" as well, it doesn't hurt).</para>
                        </listitem>
                        <listitem>
                            <para>eUML allows very long constructs but will also quickly increase
                                your compile time on some compilers (VC9, VC10) with buggy decltype
                                support (I suspect some at least quadratic algorithms there). Even
                                g++ 4.4 shows some regression compared to 4.3 and will crash if the
                                constructs become too big.</para>
                        </listitem>
                        <listitem>
                            <para>Need to overwrite the mpl::vector/list default-size-limit of 20
                                and fusion default vector size of 10 if more than 10 states found in
                                a state machine</para>
                        </listitem>
                    </itemizedlist>
                </para>
            </sect1>
            <sect1>
                <title> Compilers corner </title>
                <para>Compilers are sometimes full of surprises and such strange errors happened in
                    the course of the development that I wanted to list the most fun for readers’
                    entertainment.</para>
                <para><emphasis role="underline">VC8</emphasis>: </para>
                <programlisting>template &lt;class StateType>
typename ::boost::enable_if&lt;
       typename ::boost::mpl::and_&lt;
                typename ::boost::mpl::not_&lt;
                    typename has_exit_pseudo_states&lt;StateType>::type
                >::type,
                typename ::boost::mpl::not_&lt;
                    typename is_pseudo_exit&lt;StateType>::type
                >::type 
       >::type,
       BaseState*>::type                   </programlisting>
                <para>I get the following error:</para>
                <para>error C2770: invalid explicit template argument(s) for '`global
                    namespace'::boost::enable_if&lt;...>::...' </para>
                <para>If I now remove the first “::” in ::boost::mpl , the compiler shuts up. So in
                    this case, it is not possible to follow Boost’s guidelines.</para>
                <para><emphasis role="underline">VC9</emphasis>:<itemizedlist>
                        <listitem>
                            <para>This one is my all times’ favorite. Do you know why the exit
                                pseudo states are referenced in the transition table with a
                                “submachine::exit_pt” ? Because “exit” will crash the compiler.
                                “Exit” is not possible either because it will crash the compiler on
                                one machine, but not on another (the compiler was installed from the
                                same disk).</para>
                        </listitem>
                        <listitem>
                            <para>Sometimes, removing a policy crashes the compiler, so some
                                versions are defining a dummy policy called WorkaroundVC9.</para>
                        </listitem>
                        <listitem>
                            <para>Typeof: While g++ and VC9 compile “standard” state machines in
                                comparable times, Typeof (while in both ways natively supported)
                                seems to behave in a quadratic complexity with VC9 and VC10.</para>
                        </listitem>
                        <listitem>
                            <para>eUML: in case of a compiler crash, changing the order of state
                                definitions (first states without entry or exit) sometimes solves
                                the problem.</para>
                        </listitem>
                    </itemizedlist></para>
                <para><emphasis role="underline">g++ 4.x</emphasis>: Boring compiler, almost all is
                    working almost as expected. Being not a language lawyer I am unsure about the
                    following “Typeof problem”. VC9 and g++ disagree on the question if you can
                    derive from the BOOST_TYPEOF generated type without first defining a typedef. I
                    will be thankful for an answer on this. I only found two ways to break the compiler:<itemizedlist>
                        <listitem>
                            <para>Add more eUML constructs until something explodes (especially with
                                g++-4.4) </para>
                        </listitem>
                        <listitem>
                            <para>The build_terminate function uses 2 mpl::push_back instead of
                                mpl::insert_range because g++ would not accept insert_range.</para>
                        </listitem>
                    </itemizedlist></para>
                <para>You can test your compiler’s decltype implementation with the <link
                        xlink:href="examples/CompilerStressTestEuml.cpp">following stress
                        test</link> and reactivate the commented-out code until the compiler
                    crashes.</para>
            </sect1>
        </chapter>
        <chapter>
            <title>Questions &amp; Answers, tips</title>
            <para><emphasis role="underline">Where should I define a state machine?</emphasis>: The
                tutorials are implemented in a simple cpp source file for simplicity. I want to
                model dynamic behavior of a class as a state machine, how should I define the state
                machine?</para>
            <para><emphasis role="underline">Answer</emphasis>: Usually you'll want to implement the
                state machine as an attribute of the class. Unfortunately, a concrete state machine
                is a typedef, which cannot be forward-declared. This leaves you with two
                possibilities: <itemizedlist>
                    <listitem>
                        <para>Provide the state machine definition inside the header class and
                            contain an instance as attribute. Simple, but with several drawbacks:
                            using namespace directives are not advised, and compile-time cost for
                            all modules including the header.</para>
                    </listitem>
                    <listitem>
                        <para>Keep the state machine as (shared) pointer to void inside the <link
                                xlink:href="examples/FsmAsPtr.hpp">class definition</link>, and
                            implement the state machine in the <link
                                xlink:href="examples/FsmAsPtr.cpp">cpp file</link>. Minimum
                            compile-time, using directives are okay, but the state machine is now
                            located inside the heap.</para>
                    </listitem>
                </itemizedlist></para>
            <para><emphasis role="underline">Question</emphasis>: on_entry gets as argument, the
                sent event. What event do I get when the state becomes default-activated (because it
                is an initial state)?</para>
            <para>
                <emphasis role="underline">Answer</emphasis>: To allow you to know that the state
                was default-activated, MSM generates a boost::msm::InitEvent default event. </para>
            <para><emphasis role="underline">Question</emphasis>: Why do I see no call to
                no_transition in my submachine? </para>
            <para><emphasis role="underline">Answer</emphasis>: Because of the priority rule defined
                by UML. It says that in case of transition conflict, the most inner state has a
                higher priority. So after asking the inner state, the containing composite has to be
                also asked to handle the transition and could find a possible transition.</para>
            <para><emphasis role="underline">Question</emphasis>: Why do I get a compile error
                saying the compiler cannot convert to a function ...Fsm::*(some_event)? </para>
            <para><emphasis role="underline">Answer</emphasis>: You probably defined a transition
                triggered by the event some_event, but used a guard/action method taking another
                event. </para>
            <para><emphasis role="underline">Question</emphasis>: Why do I get a compile error
                saying something like “too few” or “too many” template arguments? </para>
            <para><emphasis role="underline">Answer</emphasis>: You probably defined a transition in
                form of a a_row or g_row where you wanted just a _row or the other way around. With
                Row, it could mean that you forgot a "none". </para>
            <para><emphasis role="underline">Question</emphasis>: Why do I get a very long compile
                error when I define more than 20 rows in the transition table? </para>
            <para><emphasis role="underline">Answer</emphasis>: MSM uses Boost.MPL under the hood
                and this is the default maximum size. Please define the following 3 macros before
                including any MSM headers: </para>
            <programlisting>#define BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS
#define BOOST_MPL_LIMIT_VECTOR_SIZE 30 // or whatever you need               
#define BOOST_MPL_LIMIT_MAP_SIZE 30 // or whatever you need </programlisting>
            <para><emphasis role="underline">Question</emphasis>: Why do I get this error: ”error
                C2977: 'boost::mpl::vector' : too many template arguments”? </para>
            <para><emphasis role="underline">Answer</emphasis>: The first possibility is that you
                defined a transition table as, say, vector17 and have 18 entries. The second is that
                you have 17 entries and have a composite state. Under the hood, MSM adds a row for
                every event in the composite transition table. The third one is that you used a
                mpl::vector without the number of entries but are close to the MPL default of 50 and
                have a composite, thus pushing you above 50. Then you need mpl/vector60/70….hpp and
                a mpl/map60/70….hpp </para>
            <para><emphasis role="underline">Question</emphasis>: Why do I get a very long compile
                error when I define more than 10 states in a state machine? </para>
            <para><emphasis role="underline">Answer</emphasis>: MSM uses Boost.Fusion under the hood
                and this is the default maximum size. Please define the following macro before
                including any MSM headers: </para>
            <programlisting>#define FUSION_MAX_VECTOR_SIZE 20 // or whatever you need </programlisting>
        </chapter>
        <chapter>
            <title>Internals</title>
            <para>This chapter describes the internal machinery of the back-end, which can be useful
                for UML experts but can be safely ignored for most users. For implementers, the
                interface between front- and back- end is also described in detail.</para>
            <sect1>
                <title><command xml:id="run-to-completion"/>Backend: Run To Completion</title>
                <para>The back-end implements the following run-to completion algorithm:<itemizedlist>
                        <listitem>
                            <para>Check if one region of the concrete state machine is in a
                                terminate or interrupt state. If yes, event processing is disabled
                                while the condition lasts (forever for a terminate pseudo-state,
                                while active for an interrupt pseudo-state).</para>
                        </listitem>
                        <listitem>
                            <para>If the message queue feature is enabled and if the state machine
                                is already processing an event, push the currently processed event
                                into the queue and end processing. Otherwise, remember that the
                                state machine is now processing an event and continue.</para>
                        </listitem>
                        <listitem>
                            <para>If the state machine detected that no deferred event is used, skip
                                this step. Otherwise, mark the first deferred event from the
                                deferred queue as active.</para>
                        </listitem>
                        <listitem>
                            <para>Now start the core of event dispatching. If exception handling is
                                activated, this will happen inside a try/catch block and the
                                front-end <code>exception_caught</code> is called if an exception
                                occurs. </para>
                        </listitem>
                        <listitem>
                            <para>The event is now dispatched in turn to every region, in the order
                                defined by the initial state front-end definition. This will, for
                                every region, call the corresponding front-end transition definition
                                (the "row" or "Row" of the transition table).</para>
                        </listitem>
                        <listitem>
                            <para>Without transition conflict, if for a given region a transition is
                                possible, the guard condition is checked. If it returns
                                    <code>true</code>, the transition processing continues and the
                                current state's exit action is called, followed by the transition
                                action behavior and the new active state's entry behavior.</para>
                        </listitem>
                        <listitem>
                            <para>With transition conflicts (several possible transitions,
                                disambiguated by mutually exclusive guard conditions), the guard
                                conditions are tried in reverse order of their transition definition
                                in the transition table. The first one returning <code>true</code>
                                selects its transition. Note that this is not defined by the UML
                                standard, which simply specifies that if the guard conditions are
                                not mutually exclusive, the state machine is ill-formed and the
                                behaviour undefined. Relying on this implementation-specific
                                behaviour will make it harder for the developer to support another
                                state machine framework.</para>
                        </listitem>
                        <listitem>
                            <para>If at least one region processes the event, this event is seen as
                                having been accepted. If not, the library calls
                                    <code>no_transition</code> on the state machine for every
                                contained region.</para>
                        </listitem>
                        <listitem>
                            <para>If the currently active state is a submachine, the behaviour is
                                slightly different. The UML standard specifies that internal
                                transitions have to be tried first, so the event is first dispatched
                                to the submachine. Only if the submachine does not accept the event
                                are other (non internal) transitions tried.</para>
                        </listitem>
                        <listitem>
                            <para>This back-end supports simple states' and submachines' internal
                                transitions. These are provided in the state's
                                    <code>internal_transition_table</code> type. Transitions defined
                                in this table are added at the end of the main state machine's
                                transition table, but with a lesser priority than the submachine's
                                transitions (defined in <code>transition_table</code>). This means,
                                for simple states, that these transitions have higher priority than
                                non-internal transitions, conform to the UML standard which gives
                                higher priority to deeper-level transitions. For submachines, this
                                is a non-standard addition which can help make event processing
                                faster by giving a chance to bypass subregion processing. With
                                standard UML, one would need to add a subregion only to process
                                these internal transitions, which would be slower.</para>
                        </listitem>
                        <listitem>
                            <para>After the dispatching itself, the deferred event marked in step 3
                                (if any) now gets a chance of processing.</para>
                        </listitem>
                        <listitem>
                            <para>Then, events queued in the message queue also get a dispatching
                                chance</para>
                        </listitem>
                        <listitem>
                            <para>Finally, completion / anonymous transitions, if to be found in the
                                transition table, also get their dispatching chance.</para>
                        </listitem>
                    </itemizedlist></para>
                <para>This algorithm illustrates how the back-end configures itself at compile-time
                    as much as possible. Every feature not found in a given state machine definition
                    is deactivated and has therefore no runtime cost. Completion events, deferred
                    events, terminate states, dispatching to several regions, internal transitions
                    are all deactivated if not used. User configuration is only for exception
                    handling and message queue necessary.</para>
            </sect1>
            <sect1>
                <title><command xml:id="internals-front-back-interface"/>Frontend / Backend
                    interface</title>
                <para>The design of MSM tries to make front-ends and back-ends (later) to be as
                    interchangeable as possible. Of course, no back-end will ever implement every
                    feature defined by any possible front-end and inversely, but the goal is to make
                    it as easy as possible to extend the current state of the library.</para>
                <para>To achieve this, MSM divides the functionality between both sides: the
                    front-end is a sort of user interface and is descriptive, the back-end
                    implements the state machine engine.</para>
                <para>MSM being based on a transition table, a concrete state machine (or a given
                    front-end) must provide a transition_table. This transition table must be made
                    of rows. And each row must tell what kind of transition it is and implement the
                    calls to the actions and guards. A state machine must also define its regions
                    (marked by initial states) And that is about the only constraints for
                    front-ends. How the rows are described is implementer's choice. </para>
                <para>Every row must provide:</para>
                <itemizedlist>
                    <listitem>
                        <para>A <code>Source</code> typedef indicating, well, the type of the source
                            state.</para>
                    </listitem>
                    <listitem>
                        <para>A <code>Target</code> typedef indicating, well, the type of the target
                            state.</para>
                    </listitem>
                    <listitem>
                        <para>A <code>Evt</code> typedef indicating the type of the event triggering
                            the transition.</para>
                    </listitem>
                    <listitem>
                        <para>A <code>row_type_tag</code> typedef indicating the type of the
                            transition.</para>
                    </listitem>
                    <listitem>
                        <para>Rows having a type requiring transition actions must provide a static
                            function <code>action_call</code> with the following signature: <code>
                                template &lt;class Fsm,class SourceState,class TargetState,class
                                AllStates> </code></para>
                        <para><code>static void action_call (Fsm&amp; fsm, Event const&amp; evt,
                                SourceState&amp;, TargetState&amp;, AllStates&amp;) </code></para>
                        <para>The function gets as parameters the (back-end) state machine, the
                            event, source and target states and a container (in the current
                            back-end, a fusion::set) of all the states defined in the state machine.
                            For example, as the back-end has the front-end as basic class,
                                <code>action_call</code> is simply defined as
                                <code>(fsm.*action)(evt)</code>.</para>
                    </listitem>
                    <listitem>
                        <para>Rows having a type requiring a guard must provide a static function
                                <code>guard_call</code> with the following signature:<code
                            > </code></para>
                        <para><code>template &lt;class Fsm,class SourceState,class TargetState,class
                                AllStates></code></para>
                        <para><code>static bool guard_call (Fsm&amp;, Event const&amp;,
                                SourceState&amp;, TargetState&amp;, AllStates&amp;)</code></para>
                    </listitem>
                    <listitem>
                        <para>The possible transition (row) types are:<itemizedlist>
                                <listitem>
                                    <para>a_row_tag: a transition with actions and no guard</para>
                                </listitem>
                                <listitem>
                                    <para>g_row_type: a transition with a guard and no
                                        actions</para>
                                </listitem>
                                <listitem>
                                    <para>_row_tag: a transition without actions or guard</para>
                                </listitem>
                                <listitem>
                                    <para>row_tag: a transition with guard and actions</para>
                                </listitem>
                                <listitem>
                                    <para>a_irow_tag: an internal transition (defined inside the
                                            <code>transition_table</code>) with actions</para>
                                </listitem>
                                <listitem>
                                    <para>g_irow_tag: an internal transition (defined inside the
                                            <code>transition_table</code>) with guard</para>
                                </listitem>
                                <listitem>
                                    <para>irow_tag: an internal transition (defined inside the
                                            <code>transition_table</code>) with actions and
                                        guards</para>
                                </listitem>
                                <listitem>
                                    <para>_irow_tag: an internal transition (defined inside the
                                            <code>transition_table</code>) without action or guard.
                                        Due to higher priority for internal transitions, this is
                                        equivalent to a "ignore event"</para>
                                </listitem>
                                <listitem>
                                    <para>sm_a_i_row_tag: an internal transition (defined inside the
                                            <code>internal_transition_table</code>) with
                                        actions</para>
                                </listitem>
                                <listitem>
                                    <para>sm_g_i_row_tag: an internal transition (defined inside the
                                            <code>internal_transition_table</code>) with
                                        guard</para>
                                </listitem>
                                <listitem>
                                    <para>sm_i_row_tag: an internal transition (defined inside the
                                            <code>internal_transition_table</code>) with actions and
                                        guards</para>
                                </listitem>
                                <listitem>
                                    <para>sm__i_row_tag: an internal transition (defined inside the
                                            <code>internal_transition_table</code>) without action
                                        or guard. Due to higher priority for internal transitions,
                                        this is quivalent to a "ignore event"</para>
                                </listitem>
                            </itemizedlist></para>
                    </listitem>
                </itemizedlist>
                <para>Furthermore, a front-end must provide the definition of states and state
                    machines. State machine definitions must provide (the implementer is free to
                    provide it or let it be done by every concrete state machine. Different MSM
                    front-ends took one or the other approach):<itemizedlist>
                        <listitem>
                            <para><code>initial_state</code>: This typedef can be a single state or
                                a mpl container and provides the initial states defining one or
                                several orthogonal regions.</para>
                        </listitem>
                        <listitem>
                            <para><code>transition_table</code>: This typedef is a MPL sequence of
                                transition rows.</para>
                        </listitem>
                        <listitem>
                            <para><code>configuration</code>: this typedef is a MPL sequence of
                                known types triggering special behavior in the back-end, for example
                                if a concrete fsm requires a message queue or exception
                                catching.</para>
                        </listitem>
                    </itemizedlist></para>
                <para>States and state machines must both provide a (possibly empty) definition of:<itemizedlist>
                        <listitem>
                            <para><code>flag_list</code>: the flags being active when this state or
                                state machine become the current state of the fsm.</para>
                        </listitem>
                        <listitem>
                            <para><code>deferred_events</code>: events being automatically deferred
                                when the state is the current state of the fsm.</para>
                        </listitem>
                        <listitem>
                            <para><code>internal_transition_table</code>: the internal transitions
                                of this state.</para>
                        </listitem>
                        <listitem>
                            <para><code>on_entry</code> and <code>on_exit</code> methods.</para>
                        </listitem>
                    </itemizedlist></para>
            </sect1>
            <sect1>
                <title><command xml:id="internals-state-id"/> Generated state ids </title>
                <para>Normally, one does not need to know the ids are generated for all the states
                    of a state machine, unless for debugging purposes, like the pstate function does
                    in the tutorials in order to display the name of the current state. This section
                    will show how to automatically display typeid-generated names, but these are not
                    very readable on all platforms, so it can help to know how the ids are
                    generated. The ids are generated using the transition table, from the “Start”
                    column up to down, then from the “Next” column, up to down, as shown in the next
                    image: </para>
                <para><inlinemediaobject>
                        <imageobject>
                            <imagedata fileref="images/AnnexA.jpg" width="90%" scalefit="1"/>
                        </imageobject>
                    </inlinemediaobject></para>
                <para>Stopped will get id 0, Open id 1, ErrorMode id 6 and SleepMode (seen only in
                    the “Next” column) id 7. If you have some implicitly created states, like
                    transition-less initial states or states created using the explicit_creation
                    typedef, these will be added as a source at the end of the transition table. If
                    you have submachine states, a row will be added for them at the end of the
                    table, after the automatically or explicitly created states, which can change
                    their id. The next help you will need for debugging would be to call the
                    current_state method of the state_machine class, then the display_type helper to
                    generate a readable name from the id. If you do not want to go through the
                    transition table to fill an array of names, the library provides another helper,
                    fill_state_names, which, given an array of sufficient size (please see next
                    section to know how many states are defined in the state machine), will fill it
                    with typeid-generated names. </para>
            </sect1>
            <sect1>
                <title>Metaprogramming tools</title>
                <para>We can find for the transition table more uses than what we have seen so far.
                    Let's suppose you need to write a coverage tool. A state machine would be
                    perfect for such a job, if only it could provide some information about its
                    structure. Thanks to the transition table and Boost.MPL, it does.</para>
                <para>What is needed for a coverage tool? You need to know how many states are
                    defined in the state machine, and how many events can be fired. This way you can
                    log the fired events and the states visited in the life of a concrete machine
                    and be able to perform some coverage analysis, like “fired 65% of all possible
                    events and visited 80% of the states defined in the state machine”. To achieve
                    this, MSM provides a few useful tools:<itemizedlist>
                        <listitem>
                            <para>generate_state_set&lt;transition table>: returns a mpl::set of all
                                the states defined in the table.</para>
                        </listitem>
                        <listitem>
                            <para>generate_event_set&lt;transition table>: returns a mpl::set of all
                                the events defined in the table.</para>
                        </listitem>
                        <listitem>
                            <para>using mpl::size&lt;>::value you can get the number of elements in
                                the set.</para>
                        </listitem>
                        <listitem>
                            <para>display_type defines an operator() sending typeid(Type).name() to
                                cout.</para>
                        </listitem>
                        <listitem>
                            <para>fill_state_names fills an array of char const* with names of all
                                states (found by typeid)</para>
                        </listitem>
                        <listitem>
                            <para>using mpl::for_each on the result of generate_state_set and
                                generate_event_set passing display_type as argument will display all
                                the states of the state machine.</para>
                        </listitem>
                        <listitem>
                            <para>let's suppose you need to recursively find the states and events
                                defined in the composite states and thus also having a transition
                                table. Calling recursive_get_transition_table&lt;Composite> will
                                return you the transition table of the composite state, recursively
                                adding the transition tables of all sub-state machines and
                                sub-sub...-sub-state machines. Then call generate_state_set or
                                generate_event_set on the result to get the full list of states and
                                events. </para>
                        </listitem>
                    </itemizedlist></para>
                <para> An <link xlink:href="examples/BoostCon09Full.cpp">example</link> shows the
                    tools in action. </para>
            </sect1>
        </chapter>
        <chapter>
            <title>Acknowledgements</title>
            <para>I am in debt to the following people who helped MSM along the way.</para>
            <sect1>
                <title>MSM v2</title>
                <para>
                    <itemizedlist>
                        <listitem>
                            <para>Thanks to Dave Abrahams for managing the review</para>
                        </listitem>
                        <listitem>
                            <para>Thanks to Eric Niebler for his patience correcting my grammar
                                errors</para>
                        </listitem>
                        <listitem>
                            <para>Special thanks to Joel de Guzman who gave me very good ideas at
                                the BoostCon09. These ideas were the starting point of the redesign.
                                Any time again, Joel ☺</para>
                        </listitem>
                        <listitem>
                            <para>Thanks to Richard O’Hara for making Green Hills bring a patch in
                                less than 1 week, thus adding one more compiler to the supported
                                list.</para>
                        </listitem>
                        <listitem>
                            <para>Big thanks to those who took the time to write a review: Franz
                                Alt, David Bergman, Michael Caisse, Barend Gehrels, Darryl Greene,
                                Juraj Ivancic, Erik Nelson, Kenny Riddile.</para>
                        </listitem>
                        <listitem>
                            <para>Thanks to Matt Calabrese, Juraj Ivancic, Adam Merz and Joseph Wu
                                for reporting bugs.</para>
                        </listitem>
                        <listitem>
                            <para>Thanks to Thomas Mistretta for providing an addition to the
                                section "What do you actually do inside actions / guards".</para>
                        </listitem>
                    </itemizedlist>
                </para>
            </sect1>
            <sect1>
                <title> MSM v1</title>
                <para>
                    <itemizedlist>
                        <listitem>
                            <para>The original version of this framework is based on the brilliant
                                work of David Abrahams and Aleksey Gurtovoy who laid down the base
                                and the principles of the framework in their excellent book, “C++
                                template Metaprogramming”. The implementation also makes heavy use
                                of the boost::mpl.</para>
                        </listitem>
                        <listitem>
                            <para>Thanks to Jeff Flinn for his idea of the user-defined base state
                                and his review which allowed MSM to be presented at the
                                BoostCon09.</para>
                        </listitem>
                        <listitem>
                            <para>Thanks to my MSM v1 beta testers, Christoph Woskowski and Franz
                                Alt for using the framework with little documentation and to my
                                private reviewer, Edouard Alligand</para>
                        </listitem>
                    </itemizedlist>
                </para>
            </sect1>
        </chapter>
        <chapter>
            <title>Version history</title>
            <sect1>
                <title>From V2.20 to V2.21 (Boost 1.47)</title>
                <para>
                    <itemizedlist>
                        <listitem>
                            <para>Added a <command xlink:href="#backend-start">stop()</command>
                                method in the back-end.</para>
                        </listitem>
                        <listitem>
                            <para><command xlink:href="#eUML-phoenix">Added partial support for
                                    Boost.Phoenix functors in eUML</command></para>
                        </listitem>
                        <listitem>
                            <para>Added the possibility to choose when <command xlink:href="#backend-state-switch">state switching</command>
                                occurs.</para>
                        </listitem>
                        <listitem>
                            <para>Bugfixes<itemizedlist>
                                    <listitem>
                                        <para>Trac 5117, 5253, 5533, 5573</para>
                                    </listitem>
                                    <listitem>
                                        <para>gcc warnings about unused variables</para>
                                    </listitem>
                                    <listitem>
                                        <para>better implemenation of favor_compile_time back-end
                                            policy</para>
                                    </listitem>
                                    <listitem>
                                        <para>bug with eUML and state construction</para>
                                    </listitem>
                                    <listitem>
                                        <para>incorrect eUML event and state macros</para>
                                    </listitem>
                                    <listitem>
                                        <para>incorrect event type passed to a direct entry state's
                                            on_entry action</para>
                                    </listitem>
                                    <listitem>
                                        <para>more examples</para>
                                    </listitem>
                                </itemizedlist></para>
                        </listitem>
                    </itemizedlist>
                </para>
            </sect1>
            <sect1>
                <title>From V2.12 to V2.20 (Boost 1.46)</title>
                <para>
                    <itemizedlist>
                        <listitem>
                            <para>Compile-time state machine analysis using mpl_graph:</para>
                            <itemizedlist>
                                <listitem>
                                    <para><command xlink:href="#backend-compile-time-analysis">checking of region orthogonality</command>.</para>
                                </listitem>
                                <listitem>
                                    <para><command xlink:href="#backend-compile-time-analysis">search for unreachable states</command>.</para>
                                </listitem>
                                <listitem>
                                    <para><command xlink:href="#explicit-entry-no-region-id">automatic region index search for pseudo entry or explicit
                                        entry states</command>.</para>
                                </listitem>
                            </itemizedlist>
                        </listitem>
                        <listitem>
                            <para><command xlink:href="#backend-boost-parameter">Boost.Parameter interface definition</command> for
                                msm::back::state_machine&lt;> template arguments.</para>
                        </listitem>
                        <listitem>
                            <para><command xlink:href="#backend-queues">Possibility to provide a
                                container</command> for the event and deferred event queues. A
                                policy implementation based on a more efficient Boost.CircularBuffer
                                is provided.</para>
                        </listitem>
                        <listitem>
                            <para>msm::back::state_machine&lt;>::is_flag_active method made
                                const.</para>
                        </listitem>
                        <listitem>
                            <para>added possibility to <command xlink:href="#backend-enqueueing"
                                >enqueue events</command> for delayed processing.</para>
                        </listitem>
                        <listitem>
                            <para>Bugfixes<itemizedlist>
                                <listitem>
                                    <para>Trac 4926</para>
                                </listitem>
                                <listitem>
                                    <para>stack overflow using the Defer functor</para>
                                </listitem>
                                <listitem>
                                    <para>anonymous transition of a submachine not called for
                                        the initial state</para>
                                </listitem>
                            </itemizedlist></para>
                        </listitem>
                    </itemizedlist>
                </para>
            </sect1>
            <sect1>
                <title>From V2.10 to V2.12  (Boost 1.45)</title>
                <para>
                    <itemizedlist>
                        <listitem>
                            <para>Support for <command xlink:href="#back-end-serialization">serialization</command></para>
                        </listitem>
                        <listitem>
                            <para><command xlink:href="#eUML-reuse-functor">Possibility to use
                                normal functors</command> (from functor front-end) in
                                eUML.</para>
                        </listitem>
                        <listitem>
                            <para><command xlink:href="#backend-fsm-constructor-args">New constructors</command> where substates / submachines can be taken as
                                arguments. This allows passing arguments to the constructor of a
                                submachine.</para>
                        </listitem>
                        <listitem>
                            <para>Bugfixes</para>
                        </listitem>
                    </itemizedlist>
                </para>
            </sect1>
            <sect1>
                <title>From V2.0 to V2.12  (Boost 1.44)</title>
                <para>
                    <itemizedlist>
                        <listitem>
                            <para>New documentation</para>
                        </listitem>
                        <listitem>
                            <para>Internal transitions. Either as part of the transition table or
                                using a state's internal transition table</para>
                        </listitem>
                        <listitem>
                            <para>increased dispatch and copy speed</para>
                        </listitem>
                        <listitem>
                            <para><command xlink:href="#basic-row2">new row types</command> for the
                                basic front-end</para>
                        </listitem>
                        <listitem>
                            <para>new eUML syntax, better attribute support, macros to ease
                                developer's life. Even VC8 seems to like it better.</para>
                        </listitem>
                        <listitem>
                            <para>New policy for reduced compile-time at the cost of dispatch
                                speed</para>
                        </listitem>
                        <listitem>
                            <para>Support for base events</para>
                        </listitem>
                        <listitem>
                            <para>possibility to choose the initial event</para>
                        </listitem>
                    </itemizedlist>
                </para>
            </sect1>
        </chapter>
    </part>
    <part>
        <title><command xml:id="Reference-begin"/>Reference</title>
        <chapter>
            <title>eUML operators and basic helpers</title>
            <para>The following table lists the supported operators: </para>
            <para>
                <table frame="all">
                    <title>Operators and state machine helpers</title>
                    <tgroup cols="3">
                        <colspec colname="c1" colnum="1"/>
                        <colspec colname="c2" colnum="2"/>
                        <colspec colname="c3" colnum="3"/>
                        <thead>
                            <row>
                                <entry>eUML function / operator</entry>
                                <entry>Description</entry>
                                <entry>Functor</entry>
                            </row>
                        </thead>
                        <tbody>
                            <row>
                                <entry>&amp;&amp;</entry>
                                <entry>Calls lazily Action1&amp;&amp; Action2</entry>
                                <entry>And_</entry>
                            </row>
                            <row>
                                <entry>||</entry>
                                <entry>Calls lazily Action1|| Action2</entry>
                                <entry>Or_</entry>
                            </row>
                            <row>
                                <entry>!</entry>
                                <entry>Calls lazily !Action1</entry>
                                <entry>Not_</entry>
                            </row>
                            <row>
                                <entry>!=</entry>
                                <entry>Calls lazily Action1 != Action2</entry>
                                <entry>NotEqualTo_</entry>
                            </row>
                            <row>
                                <entry>==</entry>
                                <entry>Calls lazily Action1 == Action2</entry>
                                <entry>EqualTo_</entry>
                            </row>
                            <row>
                                <entry>></entry>
                                <entry>Calls lazily Action1 > Action2</entry>
                                <entry>Greater_</entry>
                            </row>
                            <row>
                                <entry>>=</entry>
                                <entry>Calls lazily Action1 >= Action2</entry>
                                <entry>Greater_Equal_</entry>
                            </row>
                            <row>
                                <entry>&lt;</entry>
                                <entry>Calls lazily Action1 &lt; Action2</entry>
                                <entry>Less_</entry>
                            </row>
                            <row>
                                <entry>&lt;=</entry>
                                <entry>Calls lazily Action1 &lt;= Action2</entry>
                                <entry>Less_Equal_</entry>
                            </row>
                            <row>
                                <entry>&amp;</entry>
                                <entry>Calls lazily Action1 &amp; Action2</entry>
                                <entry>Bitwise_And_</entry>
                            </row>
                            <row>
                                <entry>|</entry>
                                <entry>Calls lazily Action1 | Action2</entry>
                                <entry>Bitwise_Or_</entry>
                            </row>
                            <row>
                                <entry>^</entry>
                                <entry>Calls lazily Action1 ^ Action2</entry>
                                <entry>Bitwise_Xor_</entry>
                            </row>
                            <row>
                                <entry>--</entry>
                                <entry>Calls lazily --Action1 / Action1--</entry>
                                <entry>Pre_Dec_ / Post_Dec_</entry>
                            </row>
                            <row>
                                <entry>++</entry>
                                <entry>Calls lazily ++Action1 / Action1++</entry>
                                <entry>Pre_Inc_ / Post_Inc_</entry>
                            </row>
                            <row>
                                <entry>/</entry>
                                <entry>Calls lazily Action1 / Action2</entry>
                                <entry>Divides_</entry>
                            </row>
                            <row>
                                <entry>/=</entry>
                                <entry>Calls lazily Action1 /= Action2</entry>
                                <entry>Divides_Assign_</entry>
                            </row>
                            <row>
                                <entry>*</entry>
                                <entry>Calls lazily Action1 * Action2</entry>
                                <entry>Multiplies_</entry>
                            </row>
                            <row>
                                <entry>*=</entry>
                                <entry>Calls lazily Action1 *= Action2</entry>
                                <entry>Multiplies_Assign_</entry>
                            </row>
                            <row>
                                <entry>+ (binary)</entry>
                                <entry>Calls lazily Action1 + Action2</entry>
                                <entry>Plus_</entry>
                            </row>
                            <row>
                                <entry>+ (unary)</entry>
                                <entry>Calls lazily +Action1</entry>
                                <entry>Unary_Plus_</entry>
                            </row>
                            <row>
                                <entry>+=</entry>
                                <entry>Calls lazily Action1 += Action2</entry>
                                <entry>Plus_Assign_</entry>
                            </row>
                            <row>
                                <entry>- (binary)</entry>
                                <entry>Calls lazily Action1 - Action2</entry>
                                <entry>Minus_</entry>
                            </row>
                            <row>
                                <entry>- (unary)</entry>
                                <entry>Calls lazily -Action1</entry>
                                <entry>Unary_Minus_</entry>
                            </row>
                            <row>
                                <entry>-=</entry>
                                <entry>Calls lazily Action1 -= Action2</entry>
                                <entry>Minus_Assign_</entry>
                            </row>
                            <row>
                                <entry>%</entry>
                                <entry>Calls lazily Action1 % Action2</entry>
                                <entry>Modulus_</entry>
                            </row>
                            <row>
                                <entry>%=</entry>
                                <entry>Calls lazily Action1 %= Action2</entry>
                                <entry>Modulus_Assign_</entry>
                            </row>
                            <row>
                                <entry>>></entry>
                                <entry>Calls lazily Action1 >> Action2</entry>
                                <entry>ShiftRight_</entry>
                            </row>
                            <row>
                                <entry>>>=</entry>
                                <entry>Calls lazily Action1 >>= Action2</entry>
                                <entry>ShiftRight_Assign_</entry>
                            </row>
                            <row>
                                <entry>&lt;&lt;</entry>
                                <entry>Calls lazily Action1 &lt;&lt; Action2</entry>
                                <entry>ShiftLeft_</entry>
                            </row>
                            <row>
                                <entry>&lt;&lt;=</entry>
                                <entry>Calls lazily Action1 &lt;&lt;= Action2</entry>
                                <entry>ShiftLeft_Assign_</entry>
                            </row>
                            <row>
                                <entry>[] (works on vector, map, arrays)</entry>
                                <entry>Calls lazily Action1 [Action2]</entry>
                                <entry>Subscript_</entry>
                            </row>
                            <row>
                                <entry>if_then_else_(Condition,Action1,Action2)</entry>
                                <entry>Returns either the result of calling Action1 or the result of
                                    calling Action2</entry>
                                <entry>If_Else_</entry>
                            </row>
                            <row>
                                <entry>if_then_(Condition,Action)</entry>
                                <entry>Returns the result of calling Action if Condition</entry>
                                <entry>If_Then_</entry>
                            </row>
                            <row>
                                <entry>while_(Condition, Body)</entry>
                                <entry>While Condition(), calls Body(). Returns nothing</entry>
                                <entry>While_Do_</entry>
                            </row>
                            <row>
                                <entry>do_while_(Condition, Body)</entry>
                                <entry>Calls Body() while Condition(). Returns nothing</entry>
                                <entry>Do_While_</entry>
                            </row>
                            <row>
                                <entry>for_(Begin,Stop,EndLoop,Body)</entry>
                                <entry>Calls for(Begin;Stop;EndLoop){Body;}</entry>
                                <entry>For_Loop_</entry>
                            </row>
                            <row>
                                <entry>process_(Event [,fsm1] [,fsm2] [,fsm3] [,fsm4])</entry>
                                <entry>Processes Event on the current state machine (if no fsm
                                    specified) or on up to 4 state machines returned by an
                                    appropriate functor.</entry>
                                <entry>Process_</entry>
                            </row>
                            <row>
                                <entry>process2_(Event, Data [,fsm1] [,fsm2] [,fsm3])</entry>
                                <entry>Processes Event on the current state machine (if no fsm
                                    specified) or on up to 2 state machines returned by an
                                    appropriate functor. The event is copy-constructed from what
                                    Data() returns.</entry>
                                <entry>Process2_</entry>
                            </row>
                            <row>
                                <entry>is_flag_(Flag [,fsm])</entry>
                                <entry>Calls is_flag_active() on the current state machine or the
                                    one returned by calling fsm.</entry>
                                <entry>Get_Flag_</entry>
                            </row>
                            <row>
                                <entry>event_ [(attribute name)]</entry>
                                <entry>Returns the current event (as const reference)</entry>
                                <entry>GetEvent_</entry>
                            </row>
                            <row>
                                <entry>source_ [(attribute name)]</entry>
                                <entry>Returns the source state of the currently triggered
                                    transition (as reference). If an attribute name is provided,
                                    returns the attribute by reference.</entry>
                                <entry>GetSource_</entry>
                            </row>
                            <row>
                                <entry>target_ [(attribute name)]</entry>
                                <entry>Returns the target state of the currently triggered
                                    transition (as reference). If an attribute name is provided,
                                    returns the attribute by reference.</entry>
                                <entry>GetTarget_</entry>
                            </row>
                            <row>
                                <entry>state_ [(attribute name)]</entry>
                                <entry>Returns the source state of the currently active state (as
                                    reference). Valid inside a state entry/exit action. If an
                                    attribute name is provided, returns the attribute by
                                    reference.</entry>
                                <entry>GetState_</entry>
                            </row>
                            <row>
                                <entry>fsm_ [(attribute name)]</entry>
                                <entry>Returns the current state machine (as reference). Valid
                                    inside a state entry/exit action or a transition. If an
                                    attribute name is provided, returns the attribute by
                                    reference.</entry>
                                <entry>GetFsm_</entry>
                            </row>
                            <row>
                                <entry>substate_(state_name [,fsm])</entry>
                                <entry>Returns (as reference) the state state_name referenced in the
                                    current state machine or the one given as argument.</entry>
                                <entry>SubState_</entry>
                            </row>
                        </tbody>
                    </tgroup>
                </table>
            </para>
            <para>To use these functions, you need to include: </para>
            <para><code>#include &lt;msm/front/euml/euml.hpp></code></para>
        </chapter>
        <chapter>
            <title>
                <command xml:id="eUML-STL-all"/>Functional programming </title>
            <para>To use these functions, you need to include: </para>
            <para><code>#include &lt;msm/front/euml/stl.hpp></code></para>
            <para>or the specified header in the following tables.</para>
            <para>The following tables list the supported STL algorithms: </para>
            <para>
                <command xml:id="eUML-STL-querying"/>
                <table frame="all">
                    <title>STL algorithms</title>
                    <tgroup cols="2">
                        <colspec colname="c2" colnum="1"/>
                        <colspec colname="c3" colnum="2"/>
                        <thead>
                            <row>
                                <entry>STL algorithms in querying.hpp</entry>
                                <entry>Functor</entry>
                            </row>
                        </thead>
                        <tbody>
                            <row>
                                <entry>find_(first, last, value)</entry>
                                <entry>Find_</entry>
                            </row>
                            <row>
                                <entry>find_if_(first, last, value)</entry>
                                <entry>FindIf_</entry>
                            </row>
                            <row>
                                <entry>lower_bound_(first, last, value [,opᵃ])</entry>
                                <entry>LowerBound_</entry>
                            </row>
                            <row>
                                <entry>upper_bound_(first, last, value [,opᵃ])</entry>
                                <entry>UpperBound_</entry>
                            </row>
                            <row>
                                <entry>equal_range_(first, last, value [,opᵃ])</entry>
                                <entry>EqualRange_</entry>
                            </row>
                            <row>
                                <entry>binary_search_(first, last, value [,opᵃ])</entry>
                                <entry>BinarySearch_</entry>
                            </row>
                            <row>
                                <entry>min_element_(first, last[,opᵃ])</entry>
                                <entry>MinElement_</entry>
                            </row>
                            <row>
                                <entry>max_element_(first, last[,opᵃ])</entry>
                                <entry>MaxElement_</entry>
                            </row>
                            <row>
                                <entry>adjacent_find_(first, last[,opᵃ])</entry>
                                <entry>AdjacentFind_</entry>
                            </row>
                            <row>
                                <entry>find_end_( first1, last1, first2, last2 [,op ᵃ])</entry>
                                <entry>FindEnd_</entry>
                            </row>
                            <row>
                                <entry>find_first_of_( first1, last1, first2, last2 [,op ᵃ])</entry>
                                <entry>FindFirstOf_</entry>
                            </row>
                            <row>
                                <entry>equal_( first1, last1, first2 [,op ᵃ])</entry>
                                <entry>Equal_</entry>
                            </row>
                            <row>
                                <entry>search_( first1, last1, first2, last2 [,op ᵃ])</entry>
                                <entry>Search_</entry>
                            </row>
                            <row>
                                <entry>includes_( first1, last1, first2, last2 [,op ᵃ])</entry>
                                <entry>Includes_</entry>
                            </row>
                            <row>
                                <entry>lexicographical_compare_ ( first1, last1, first2, last2 [,op
                                    ᵃ]) </entry>
                                <entry>LexicographicalCompare_</entry>
                            </row>
                            <row>
                                <entry>count_(first, last, value [,size])</entry>
                                <entry>Count_</entry>
                            </row>
                            <row>
                                <entry>count_if_(first, last, op ᵃ [,size])</entry>
                                <entry>CountIf_</entry>
                            </row>
                            <row>
                                <entry>distance_(first, last)</entry>
                                <entry>Distance_</entry>
                            </row>
                            <row>
                                <entry>mismatch _( first1, last1, first2 [,op ᵃ])</entry>
                                <entry>Mismatch_</entry>
                            </row>
                        </tbody>
                    </tgroup>
                </table>
            </para>
            <para>
                <command xml:id="eUML-STL-iteration"/>
                <table frame="all">
                    <title>STL algorithms</title>
                    <tgroup cols="2">
                        <colspec colname="c2" colnum="1"/>
                        <colspec colname="c3" colnum="2"/>
                        <thead>
                            <row>
                                <entry>STL algorithms in iteration.hpp</entry>
                                <entry>Functor</entry>
                            </row>
                        </thead>
                        <tbody>
                            <row>
                                <entry>for_each_(first,last, unary opᵃ)</entry>
                                <entry>ForEach_</entry>
                            </row>
                            <row>
                                <entry>accumulate_first, last, init [,opᵃ])</entry>
                                <entry>Accumulate_</entry>
                            </row>
                        </tbody>
                    </tgroup>
                </table>
            </para>
            <para>
                <command xml:id="eUML-STL-transformation"/>
                <table>
                    <title>STL algorithms</title>
                    <tgroup cols="2">
                        <colspec colname="c2" colnum="1"/>
                        <colspec colname="c3" colnum="2"/>
                        <thead>
                            <row>
                                <entry>STL algorithms in transformation.hpp</entry>
                                <entry>Functor</entry>
                            </row>
                        </thead>
                        <tbody>
                            <row>
                                <entry>copy_(first, last, result)</entry>
                                <entry>Copy_</entry>
                            </row>
                            <row>
                                <entry>copy_backward_(first, last, result)</entry>
                                <entry>CopyBackward_</entry>
                            </row>
                            <row>
                                <entry>reverse_(first, last)</entry>
                                <entry>Reverse_</entry>
                            </row>
                            <row>
                                <entry>reverse_copy_(first, last , result)</entry>
                                <entry>ReverseCopy_</entry>
                            </row>
                            <row>
                                <entry>remove_(first, last, value)</entry>
                                <entry>Remove_</entry>
                            </row>
                            <row>
                                <entry>remove_if_(first, last , opᵃ)</entry>
                                <entry>RemoveIf_</entry>
                            </row>
                            <row>
                                <entry>remove_copy_(first, last , output, value)</entry>
                                <entry>RemoveCopy_</entry>
                            </row>
                            <row>
                                <entry>remove_copy_if_(first, last, output, opᵃ)</entry>
                                <entry>RemoveCopyIf_</entry>
                            </row>
                            <row>
                                <entry>fill_(first, last, value)</entry>
                                <entry>Fill_</entry>
                            </row>
                            <row>
                                <entry>fill_n_(first, size, value)ᵇ</entry>
                                <entry>FillN_</entry>
                            </row>
                            <row>
                                <entry>generate_(first, last, generatorᵃ)</entry>
                                <entry>Generate_</entry>
                            </row>
                            <row>
                                <entry>generate_(first, size, generatorᵃ)ᵇ</entry>
                                <entry>GenerateN_</entry>
                            </row>
                            <row>
                                <entry>unique_(first, last [,opᵃ])</entry>
                                <entry>Unique_</entry>
                            </row>
                            <row>
                                <entry>unique_copy_(first, last, output [,opᵃ])</entry>
                                <entry>UniqueCopy_</entry>
                            </row>
                            <row>
                                <entry>random_shuffle_(first, last [,opᵃ])</entry>
                                <entry>RandomShuffle_</entry>
                            </row>
                            <row>
                                <entry>rotate_copy_(first, middle, last, output)</entry>
                                <entry>RotateCopy_</entry>
                            </row>
                            <row>
                                <entry>partition_ (first, last [,opᵃ])</entry>
                                <entry>Partition_</entry>
                            </row>
                            <row>
                                <entry>stable_partition_ (first, last [,opᵃ])</entry>
                                <entry>StablePartition_</entry>
                            </row>
                            <row>
                                <entry>stable_sort_(first, last [,opᵃ])</entry>
                                <entry>StableSort_</entry>
                            </row>
                            <row>
                                <entry>sort_(first, last [,opᵃ])</entry>
                                <entry>Sort_</entry>
                            </row>
                            <row>
                                <entry>partial_sort_(first, middle, last [,opᵃ])</entry>
                                <entry>PartialSort_</entry>
                            </row>
                            <row>
                                <entry>partial_sort_copy_ (first, last, res_first, res_last [,opᵃ]) </entry>
                                <entry>PartialSortCopy_</entry>
                            </row>
                            <row>
                                <entry>nth_element_(first, nth, last [,opᵃ])</entry>
                                <entry>NthElement_</entry>
                            </row>
                            <row>
                                <entry>merge_( first1, last1, first2, last2, output [,op ᵃ])</entry>
                                <entry>Merge_</entry>
                            </row>
                            <row>
                                <entry>inplace_merge_(first, middle, last [,opᵃ])</entry>
                                <entry>InplaceMerge_</entry>
                            </row>
                            <row>
                                <entry>set_union_(first1, last1, first2, last2, output [,op
                                    ᵃ])</entry>
                                <entry>SetUnion_</entry>
                            </row>
                            <row>
                                <entry>push_heap_(first, last [,op ᵃ])</entry>
                                <entry>PushHeap_</entry>
                            </row>
                            <row>
                                <entry>pop_heap_(first, last [,op ᵃ])</entry>
                                <entry>PopHeap_</entry>
                            </row>
                            <row>
                                <entry>make_heap_(first, last [,op ᵃ])</entry>
                                <entry>MakeHeap_</entry>
                            </row>
                            <row>
                                <entry>sort_heap_(first, last [,op ᵃ])</entry>
                                <entry>SortHeap_</entry>
                            </row>
                            <row>
                                <entry>next_permutation_(first, last [,op ᵃ])</entry>
                                <entry>NextPermutation_</entry>
                            </row>
                            <row>
                                <entry>prev_permutation_(first, last [,op ᵃ])</entry>
                                <entry>PrevPermutation_</entry>
                            </row>
                            <row>
                                <entry>inner_product_(first1, last1, first2, init [,op1ᵃ] [,op2ᵃ]) </entry>
                                <entry>InnerProduct_</entry>
                            </row>
                            <row>
                                <entry>partial_sum_(first, last, output [,opᵃ])</entry>
                                <entry>PartialSum_</entry>
                            </row>
                            <row>
                                <entry>adjacent_difference_(first, last, output [,opᵃ])</entry>
                                <entry>AdjacentDifference_</entry>
                            </row>
                            <row>
                                <entry>replace_(first, last, old_value, new_value)</entry>
                                <entry>Replace_</entry>
                            </row>
                            <row>
                                <entry>replace_if_(first, last, opᵃ, new_value)</entry>
                                <entry>ReplaceIf_</entry>
                            </row>
                            <row>
                                <entry>replace_copy_(first, last, result, old_value,
                                    new_value)</entry>
                                <entry>ReplaceCopy_</entry>
                            </row>
                            <row>
                                <entry>replace_copy_if_(first, last, result, opᵃ, new_value)</entry>
                                <entry>ReplaceCopyIf_</entry>
                            </row>
                            <row>
                                <entry>rotate_(first, middle, last)ᵇ</entry>
                                <entry>Rotate_</entry>
                            </row>
                        </tbody>
                    </tgroup>
                </table>
            </para>
            <para>
                <command xml:id="eUML-STL-container"/>
                <table>
                    <title>STL container methods</title>
                    <tgroup cols="2">
                        <colspec colname="c2" colnum="1"/>
                        <colspec colname="c3" colnum="2"/>
                        <thead>
                            <row>
                                <entry>STL container methods(common) in container.hpp</entry>
                                <entry>Functor</entry>
                            </row>
                        </thead>
                        <tbody>
                            <row>
                                <entry>container::reference front_(container)</entry>
                                <entry>Front_</entry>
                            </row>
                            <row>
                                <entry>container::reference back_(container)</entry>
                                <entry>Back_</entry>
                            </row>
                            <row>
                                <entry>container::iterator begin_(container)</entry>
                                <entry>Begin_</entry>
                            </row>
                            <row>
                                <entry>container::iterator end_(container)</entry>
                                <entry>End_</entry>
                            </row>
                            <row>
                                <entry>container::reverse_iterator rbegin_(container)</entry>
                                <entry>RBegin_</entry>
                            </row>
                            <row>
                                <entry>container::reverse_iterator rend_(container)</entry>
                                <entry>REnd_</entry>
                            </row>
                            <row>
                                <entry>void push_back_(container, value)</entry>
                                <entry>Push_Back_</entry>
                            </row>
                            <row>
                                <entry>void pop_back_(container, value)</entry>
                                <entry>Pop_Back_</entry>
                            </row>
                            <row>
                                <entry>void push_front_(container, value)</entry>
                                <entry>Push_Front_</entry>
                            </row>
                            <row>
                                <entry>void pop_front_(container, value)</entry>
                                <entry>Pop_Front_</entry>
                            </row>
                            <row>
                                <entry>void clear_(container)</entry>
                                <entry>Clear_</entry>
                            </row>
                            <row>
                                <entry>size_type capacity_(container)</entry>
                                <entry>Capacity_</entry>
                            </row>
                            <row>
                                <entry>size_type size_(container)</entry>
                                <entry>Size_</entry>
                            </row>
                            <row>
                                <entry>size_type max_size_(container)</entry>
                                <entry>Max_Size_</entry>
                            </row>
                            <row>
                                <entry>void reserve_(container, value)</entry>
                                <entry>Reserve _</entry>
                            </row>
                            <row>
                                <entry>void resize_(container, value)</entry>
                                <entry>Resize _</entry>
                            </row>
                            <row>
                                <entry>iterator insert_(container, pos, value)</entry>
                                <entry>Insert_</entry>
                            </row>
                            <row>
                                <entry>void insert_( container , pos, first, last)</entry>
                                <entry>Insert_</entry>
                            </row>
                            <row>
                                <entry>void insert_( container , pos, number, value)</entry>
                                <entry>Insert_</entry>
                            </row>
                            <row>
                                <entry>void swap_( container , other_container)</entry>
                                <entry>Swap_</entry>
                            </row>
                            <row>
                                <entry>void erase_( container , pos)</entry>
                                <entry>Erase_</entry>
                            </row>
                            <row>
                                <entry>void erase_( container , first, last) </entry>
                                <entry>Erase_</entry>
                            </row>
                            <row>
                                <entry>bool empty_( container)</entry>
                                <entry>Empty_</entry>
                            </row>
                        </tbody>
                    </tgroup>
                </table>
            </para>
            <para>
                <table>
                    <title>STL list methods</title>
                    <tgroup cols="2">
                        <colspec colname="c2" colnum="1"/>
                        <colspec colname="c3" colnum="2"/>
                        <thead>
                            <row>
                                <entry>std::list methods in container.hpp</entry>
                                <entry>Functor</entry>
                            </row>
                        </thead>
                        <tbody>
                            <row>
                                <entry>void list_remove_(container, value)</entry>
                                <entry>ListRemove_</entry>
                            </row>
                            <row>
                                <entry>void list_remove_if_(container, opᵃ)</entry>
                                <entry>ListRemove_If_</entry>
                            </row>
                            <row>
                                <entry>void list_merge_(container, other_list)</entry>
                                <entry>ListMerge_</entry>
                            </row>
                            <row>
                                <entry>void list_merge_(container, other_list, opᵃ)</entry>
                                <entry>ListMerge_</entry>
                            </row>
                            <row>
                                <entry>void splice_(container, iterator, other_list)</entry>
                                <entry>Splice_</entry>
                            </row>
                            <row>
                                <entry>void splice_(container, iterator, other_list,
                                    iterator)</entry>
                                <entry>Splice_</entry>
                            </row>
                            <row>
                                <entry>void splice_(container, iterator, other_list, first,
                                    last)</entry>
                                <entry>Splice_</entry>
                            </row>
                            <row>
                                <entry>void list_reverse_(container)</entry>
                                <entry>ListReverse_</entry>
                            </row>
                            <row>
                                <entry>void list_unique_(container)</entry>
                                <entry>ListUnique_</entry>
                            </row>
                            <row>
                                <entry>void list_unique_(container, opᵃ)</entry>
                                <entry>ListUnique_</entry>
                            </row>
                            <row>
                                <entry>void list_sort_(container)</entry>
                                <entry>ListSort_</entry>
                            </row>
                            <row>
                                <entry>void list_sort_(container, opᵃ)</entry>
                                <entry>ListSort_</entry>
                            </row>
                        </tbody>
                    </tgroup>
                </table>
            </para>
            <para>
                <table>
                    <title>STL associative container methods </title>
                    <tgroup cols="2">
                        <colspec colname="c2" colnum="1"/>
                        <colspec colname="c3" colnum="2"/>
                        <thead>
                            <row>
                                <entry>Associative container methods in container.hpp</entry>
                                <entry>Functor</entry>
                            </row>
                        </thead>
                        <tbody>
                            <row>
                                <entry>iterator insert_(container, pos, value)</entry>
                                <entry>Insert_</entry>
                            </row>
                            <row>
                                <entry>void insert_( container , first, last)</entry>
                                <entry>Insert_</entry>
                            </row>
                            <row>
                                <entry>pair&lt;iterator, bool> insert_( container , value)</entry>
                                <entry>Insert_</entry>
                            </row>
                            <row>
                                <entry>void associative_erase_( container , pos)</entry>
                                <entry>Associative_Erase_</entry>
                            </row>
                            <row>
                                <entry>void associative_erase_( container , first, last)</entry>
                                <entry>Associative_Erase_</entry>
                            </row>
                            <row>
                                <entry>size_type associative_erase_( container , key)</entry>
                                <entry>Associative_Erase_</entry>
                            </row>
                            <row>
                                <entry>iterator associative_find_( container , key)</entry>
                                <entry>Associative_Find_</entry>
                            </row>
                            <row>
                                <entry>size_type associative_count_( container , key)</entry>
                                <entry>AssociativeCount_</entry>
                            </row>
                            <row>
                                <entry>iterator associative_lower_bound_( container , key)</entry>
                                <entry>Associative_Lower_Bound_</entry>
                            </row>
                            <row>
                                <entry>iterator associative_upper_bound_( container , key)</entry>
                                <entry>Associative_Upper_Bound_</entry>
                            </row>
                            <row>
                                <entry>pair&lt;iterator, iterator> associative_equal_range_(
                                    container , key)</entry>
                                <entry>Associative_Equal_Range_</entry>
                            </row>
                        </tbody>
                    </tgroup>
                </table>
            </para>
            <para>
                <table>
                    <title>STL pair</title>
                    <tgroup cols="2">
                        <colspec colname="c2" colnum="1"/>
                        <colspec colname="c3" colnum="2"/>
                        <thead>
                            <row>
                                <entry>std::pair in container.hpp</entry>
                                <entry>Functor</entry>
                            </row>
                        </thead>
                        <tbody>
                            <row>
                                <entry>first_type first_(pair&lt;T1, T2>)</entry>
                                <entry>First_</entry>
                            </row>
                            <row>
                                <entry>second_type second_(pair&lt;T1, T2>)</entry>
                                <entry>Second_</entry>
                            </row>
                        </tbody>
                    </tgroup>
                </table>
            </para>
            <para>
                <table>
                    <title>STL string</title>
                    <tgroup cols="3">
                        <colspec colname="newCol1" colnum="1"/>
                        <colspec colname="c2" colnum="2"/>
                        <colspec colname="c3" colnum="3"/>
                        <thead>
                            <row>
                                <entry>STL string method</entry>
                                <entry>std::string method in container.hpp</entry>
                                <entry>Functor</entry>
                            </row>
                        </thead>
                        <tbody>
                            <row>
                                <entry>substr (size_type pos, size_type size)</entry>
                                <entry>string substr_(container, pos, length)</entry>
                                <entry>Substr_</entry>
                            </row>
                            <row>
                                <entry>int compare(string)</entry>
                                <entry>int string_compare_(container, another_string)</entry>
                                <entry>StringCompare_</entry>
                            </row>
                            <row>
                                <entry>int compare(char*)</entry>
                                <entry>int string_compare_(container, another_string)</entry>
                                <entry>StringCompare_</entry>
                            </row>
                            <row>
                                <entry>int compare(size_type pos, size_type size, string)</entry>
                                <entry>int string_compare_(container, pos, size,
                                    another_string)</entry>
                                <entry>StringCompare_</entry>
                            </row>
                            <row>
                                <entry>int compare (size_type pos, size_type size, string, size_type
                                    length)</entry>
                                <entry>int string_compare_(container, pos, size, another_string,
                                    length)</entry>
                                <entry>StringCompare_</entry>
                            </row>
                            <row>
                                <entry>string&amp; append(const string&amp;)</entry>
                                <entry>string&amp; append_(container, another_string)</entry>
                                <entry>Append_</entry>
                            </row>
                            <row>
                                <entry>string&amp; append (charT*)</entry>
                                <entry>string&amp; append_(container, another_string)</entry>
                                <entry>Append_</entry>
                            </row>
                            <row>
                                <entry>string&amp; append (string , size_type pos, size_type
                                    size)</entry>
                                <entry>string&amp; append_(container, other_string, pos,
                                    size)</entry>
                                <entry>Append_</entry>
                            </row>
                            <row>
                                <entry>string&amp; append (charT*, size_type size)</entry>
                                <entry>string&amp; append_(container, another_string,
                                    length)</entry>
                                <entry>Append_</entry>
                            </row>
                            <row>
                                <entry>string&amp; append (size_type size, charT)</entry>
                                <entry>string&amp; append_(container, size, char)</entry>
                                <entry>Append_</entry>
                            </row>
                            <row>
                                <entry>string&amp; append (iterator begin, iterator end)</entry>
                                <entry>string&amp; append_(container, begin, end)</entry>
                                <entry>Append_</entry>
                            </row>
                            <row>
                                <entry>string&amp; insert (size_type pos, charT*)</entry>
                                <entry>string&amp; string_insert_(container, pos,
                                    other_string)</entry>
                                <entry>StringInsert_</entry>
                            </row>
                            <row>
                                <entry>string&amp; insert(size_type pos, charT*,size_type n)</entry>
                                <entry>string&amp; string_insert_(container, pos, other_string,
                                    n)</entry>
                                <entry>StringInsert_</entry>
                            </row>
                            <row>
                                <entry>string&amp; insert(size_type pos,size_type n, charT
                                    c)</entry>
                                <entry>string&amp; string_insert_(container, pos, n, c)</entry>
                                <entry>StringInsert_</entry>
                            </row>
                            <row>
                                <entry>string&amp; insert (size_type pos, const string&amp;)</entry>
                                <entry>string&amp; string_insert_(container, pos,
                                    other_string)</entry>
                                <entry>StringInsert_</entry>
                            </row>
                            <row>
                                <entry>string&amp; insert (size_type pos, const string&amp;,
                                    size_type pos1, size_type n)</entry>
                                <entry>string&amp; string_insert_(container, pos, other_string,
                                    pos1, n)</entry>
                                <entry>StringInsert_</entry>
                            </row>
                            <row>
                                <entry>string&amp; erase(size_type pos=0, size_type n=npos)</entry>
                                <entry>string&amp; string_erase_(container, pos, n)</entry>
                                <entry>StringErase_</entry>
                            </row>
                            <row>
                                <entry>string&amp; assign(const string&amp;)</entry>
                                <entry>string&amp; string_assign_(container, another_string)</entry>
                                <entry>StringAssign_</entry>
                            </row>
                            <row>
                                <entry>string&amp; assign(const charT*)</entry>
                                <entry>string&amp; string_assign_(container, another_string)</entry>
                                <entry>StringAssign_</entry>
                            </row>
                            <row>
                                <entry>string&amp; assign(const string&amp;, size_type pos,
                                    size_type n)</entry>
                                <entry>string&amp; string_assign_(container, another_string, pos,
                                    n)</entry>
                                <entry>StringAssign_</entry>
                            </row>
                            <row>
                                <entry>string&amp; assign(const charT*, size_type n)</entry>
                                <entry>string&amp; string_assign_(container, another_string,
                                    n)</entry>
                                <entry>StringAssign_</entry>
                            </row>
                            <row>
                                <entry>string&amp; assign(size_type n, charT c)</entry>
                                <entry>string&amp; string_assign_(container, n, c)</entry>
                                <entry>StringAssign_</entry>
                            </row>
                            <row>
                                <entry>string&amp; assign(iterator first, iterator last)</entry>
                                <entry>string&amp; string_assign_(container, first, last)</entry>
                                <entry>StringAssign_</entry>
                            </row>
                            <row>
                                <entry>string&amp; replace(size_type pos, size_type n, const
                                    string&amp;)</entry>
                                <entry>string&amp; string_replace_(container, pos, n,
                                    another_string)</entry>
                                <entry>StringReplace_</entry>
                            </row>
                            <row>
                                <entry>string&amp; replace(size_type pos, size_type n, const charT*,
                                    size_type n1)</entry>
                                <entry>string&amp; string_replace_(container, pos, n,
                                    another_string, n1)</entry>
                                <entry>StringReplace_</entry>
                            </row>
                            <row>
                                <entry>string&amp; replace(size_type pos, size_type n, const
                                    charT*)</entry>
                                <entry>string&amp; string_replace_(container, pos, n,
                                    another_string)</entry>
                                <entry>StringReplace_</entry>
                            </row>
                            <row>
                                <entry>string&amp; replace(size_type pos, size_type n, size_type n1,
                                    charT c)</entry>
                                <entry>string&amp; string_replace_(container, pos, n, n1, c)</entry>
                                <entry>StringReplace_</entry>
                            </row>
                            <row>
                                <entry>string&amp; replace(iterator first, iterator last, const
                                    string&amp;)</entry>
                                <entry>string&amp; string_replace_(container, first, last,
                                    another_string)</entry>
                                <entry>StringReplace_</entry>
                            </row>
                            <row>
                                <entry>string&amp; replace(iterator first, iterator last, const
                                    charT*, size_type n)</entry>
                                <entry>string&amp; string_replace_(container, first, last,
                                    another_string, n)</entry>
                                <entry>StringReplace_</entry>
                            </row>
                            <row>
                                <entry>string&amp; replace(iterator first, iterator last, const
                                    charT*)</entry>
                                <entry>string&amp; string_replace_(container, first, last,
                                    another_string)</entry>
                                <entry>StringReplace_</entry>
                            </row>
                            <row>
                                <entry>string&amp; replace(iterator first, iterator last, size_type
                                    n, charT c)</entry>
                                <entry>string&amp; string_replace_(container, first, last, n,
                                    c)</entry>
                                <entry>StringReplace_</entry>
                            </row>
                            <row>
                                <entry>string&amp; replace(iterator first, iterator last, iterator
                                    f, iterator l)</entry>
                                <entry>string&amp; string_replace_(container, first, last, f,
                                    l)</entry>
                                <entry>StringReplace_</entry>
                            </row>
                            <row>
                                <entry>const charT* c_str()</entry>
                                <entry>const charT* c_str_(container)</entry>
                                <entry>CStr_</entry>
                            </row>
                            <row>
                                <entry>const charT* data()</entry>
                                <entry>const charT* string_data_(container)</entry>
                                <entry>StringData_</entry>
                            </row>
                            <row>
                                <entry>size_type copy(charT* buf, size_type n, size_type pos =
                                    0)</entry>
                                <entry>size_type string_copy_(container, buf, n, pos); size_type
                                    string_copy_(container, buf, n) </entry>
                                <entry>StringCopy_</entry>
                            </row>
                            <row>
                                <entry>size_type find(charT* s, size_type pos, size_type n)</entry>
                                <entry>size_type string_find_(container, s, pos, n)</entry>
                                <entry>StringFind_</entry>
                            </row>
                            <row>
                                <entry>size_type find(charT* s, size_type pos=0)</entry>
                                <entry>size_type string_find_(container, s, pos); size_type
                                    string_find_(container, s) </entry>
                                <entry>StringFind_</entry>
                            </row>
                            <row>
                                <entry>size_type find(const string&amp; s, size_type pos=0)</entry>
                                <entry>size_type string_find_(container, s, pos) size_type
                                    string_find_(container, s) </entry>
                                <entry>StringFind_</entry>
                            </row>
                            <row>
                                <entry>size_type find(charT c, size_type pos=0)</entry>
                                <entry>size_type string_find_(container, c, pos) size_type
                                    string_find_(container, c) </entry>
                                <entry>StringFind_</entry>
                            </row>
                            <row>
                                <entry>size_type rfind(charT* s, size_type pos, size_type n)</entry>
                                <entry>size_type string_rfind_(container, s, pos, n)</entry>
                                <entry>StringRFind_</entry>
                            </row>
                            <row>
                                <entry>size_type rfind(charT* s, size_type pos=npos)</entry>
                                <entry>size_type string_rfind_(container, s, pos); size_type
                                    string_rfind_(container, s) </entry>
                                <entry>StringRFind_</entry>
                            </row>
                            <row>
                                <entry>size_type rfind(const string&amp; s, size_type
                                    pos=npos)</entry>
                                <entry>size_type string_rfind_(container, s, pos); size_type
                                    string_rfind_(container, s) </entry>
                                <entry>StringRFind_</entry>
                            </row>
                            <row>
                                <entry>size_type rfind(charT c, size_type pos=npos)</entry>
                                <entry>size_type string_rfind_(container, c, pos) size_type
                                    string_rfind_(container, c) </entry>
                                <entry>StringRFind_</entry>
                            </row>
                            <row>
                                <entry>size_type find_first_of(charT* s, size_type pos, size_type
                                    n)</entry>
                                <entry>size_type find_first_of_(container, s, pos, n)</entry>
                                <entry>StringFindFirstOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_first_of (charT* s, size_type pos=0)</entry>
                                <entry>size_type find_first_of_(container, s, pos); size_type
                                    find_first_of_(container, s) </entry>
                                <entry>StringFindFirstOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_first_of (const string&amp; s, size_type
                                    pos=0)</entry>
                                <entry>size_type find_first_of_(container, s, pos); size_type
                                    find_first_of_(container, s) </entry>
                                <entry>StringFindFirstOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_first_of (charT c, size_type pos=0)</entry>
                                <entry>size_type find_first_of_(container, c, pos) size_type
                                    find_first_of_(container, c) </entry>
                                <entry>StringFindFirstOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_first_not_of(charT* s, size_type pos,
                                    size_type n)</entry>
                                <entry>size_type find_first_not_of_(container, s, pos, n)</entry>
                                <entry>StringFindFirstNotOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_first_not_of (charT* s, size_type
                                    pos=0)</entry>
                                <entry>size_type find_first_not_of_(container, s, pos); size_type
                                    find_first_not_of_(container, s) </entry>
                                <entry>StringFindFirstNotOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_first_not_of (const string&amp; s, size_type
                                    pos=0)</entry>
                                <entry>size_type find_first_not_of_(container, s, pos); size_type
                                    find_first_not_of_(container, s) </entry>
                                <entry>StringFindFirstNotOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_first_not_of (charT c, size_type
                                    pos=0)</entry>
                                <entry>size_type find_first_not_of_(container, c, pos); size_type
                                    find_first_not_of_(container, c) </entry>
                                <entry>StringFindFirstNotOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_last_of(charT* s, size_type pos, size_type
                                    n)</entry>
                                <entry>size_type find_last_of_(container, s, pos, n)</entry>
                                <entry>StringFindLastOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_last_of (charT* s, size_type pos=npos)</entry>
                                <entry>size_type find_last_of_(container, s, pos); size_type
                                    find_last_of_(container, s) </entry>
                                <entry>StringFindLastOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_last_of (const string&amp; s, size_type
                                    pos=npos)</entry>
                                <entry>size_type find_last_of_(container, s, pos); size_type
                                    find_last_of_(container, s) </entry>
                                <entry>StringFindLastOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_last_of (charT c, size_type pos=npos)</entry>
                                <entry>size_type find_last_of_(container, c, pos); size_type
                                    find_last_of_(container, c) </entry>
                                <entry>StringFindLastOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_last_not_of(charT* s, size_type pos, size_type
                                    n)</entry>
                                <entry>size_type find_last_not_of_(container, s, pos, n)</entry>
                                <entry>StringFindLastNotOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_last_not_of (charT* s, size_type
                                    pos=npos)</entry>
                                <entry>size_type find_last_not_of_(container, s, pos); size_type
                                    find_last_of_(container, s) </entry>
                                <entry>StringFindLastNotOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_last_not_of (const string&amp; s, size_type
                                    pos=npos)</entry>
                                <entry>size_type find_last_not_of_(container, s, pos); size_type
                                    find_last_not_of_(container, s) </entry>
                                <entry>StringFindLastNotOf_</entry>
                            </row>
                            <row>
                                <entry>size_type find_last_not_of (charT c, size_type
                                    pos=npos)</entry>
                                <entry>size_type find_last_not_of_(container, c, pos); size_type
                                    find_last_not_of_(container, c) </entry>
                                <entry>StringFindLastNotOf_</entry>
                            </row>
                        </tbody>
                    </tgroup>
                </table>
            </para>
            <para><emphasis role="underline">Notes</emphasis>: <itemizedlist>
                    <listitem>
                        <para>ᵃ: algorithms requiring a predicate need to make them eUML compatible
                            by wrapping them inside a Predicate_ functor. For example,
                            std::less&lt;int> => Predicate_&lt;std::less&lt;int> >()</para>
                    </listitem>
                    <listitem>
                        <para>ᵇ: If using the SGI STL implementation, these functors use the SGI
                            return value</para>
                    </listitem>
                </itemizedlist>
            </para>
        </chapter>
        <refentry>
            <refnamediv>
                <refname>Common headers</refname>
                <refpurpose>The common types used by front- and back-ends</refpurpose>
            </refnamediv>
            <refsect1>
                <title>msm/common.hpp</title>
                <para>This header provides one type, wrap, which is an empty type whose only reason
                    to exist is to be cheap to construct, so that it can be used with mpl::for_each,
                    as shown in the Metaprogramming book, chapter 9.</para>
                <classsynopsis>
                    <ooclass>
                        <classname>template &lt;class Dummy> wrap{};</classname>
                    </ooclass>
                </classsynopsis>
            </refsect1>
            <refsect1>
                <title>msm/row_tags.hpp</title>
                <para>This header contains the row type tags which front-ends can support partially
                    or totally. Please see the <command xlink:href="#internals-front-back-interface"
                        >Internals</command> section for a description of the different
                    types.</para>
            </refsect1>
        </refentry>
        <refentry>
            <refnamediv>
                <refname>Back-end</refname>
                <refpurpose>The back-end headers</refpurpose>
            </refnamediv>
            <refsect1>
                <title>msm/back/state_machine.hpp</title>
                <para> This header provides one type, state_machine, MSM's state machine engine
                    implementation.</para>
                <classsynopsis>
                    <ooclass>
                        <classname>template &lt;class Derived,class HistoryPolicy=NoHistory,class
                            CompilePolicy=favor_runtime_speed> state_machine</classname>
                    </ooclass>
                </classsynopsis>
                <refsect2>
                    <title> Template arguments </title>
                    <refsect3>
                        <title> Derived </title>
                        <para>The name of the front-end state machine definition. All three
                            front-ends are possible.</para>
                    </refsect3>
                    <refsect3>
                        <title> HistoryPolicy </title>
                        <para>The desired history. This can be: AlwaysHistory, NoHistory,
                            ShallowHistory. Default is NoHistory.</para>
                    </refsect3>
                    <refsect3>
                        <title> CompilePolicy </title>
                        <para>The trade-off performance / compile-time. There are two predefined
                            policies, favor_runtime_speed and favor_compile_time. Default is
                            favor_runtime_speed, best performance, longer compile-time. See <link
                                xlink:href="#backend-tradeof-rt-ct">the backend</link>.</para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title> methods </title>
                    <refsect3>
                        <title>start</title>
                        <para> The start methods must be called before any call to process_event. It
                            activates the entry action of the initial state(s). This allows you to
                            choose when a state machine can start. See <link
                                xlink:href="#backend-start">backend</link>.</para>
                        <methodsynopsis>
                            <methodname>void start</methodname>
                            <methodparam>
                                <funcparams/>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>process_event</title>
                        <para>The event processing method implements the double-dispatch. Each call
                            to this function with a new event type instantiates a new dispatch
                            algorithm and increases compile-time.</para>
                        <methodsynopsis>
                            <methodname>template &lt;class Event> HandledEnum
                                process_event</methodname>
                            <methodparam>
                                <funcparams>Event const&amp;</funcparams>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>current_state</title>
                        <para>Returns the ids of currently active states. You will typically need it
                            only for debugging or logging purposes.</para>
                        <methodsynopsis>
                            <methodname>const int* current_state const</methodname>
                            <methodparam>
                                <funcparams/>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>get_state_by_id</title>
                        <para>Returns the state whose id is given. As all states of a concrete state
                            machine share a common base state, the return value is a base state. If
                            the id corresponds to no state, a null pointer is returned.</para>
                        <methodsynopsis>
                            <methodname>const BaseState* get_state_by_id const</methodname>
                            <methodparam>
                                <funcparams>int id</funcparams>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>is_contained</title>
                        <para>Helper returning true if the state machine is contained as a
                            submachine of another state machine.</para>
                        <methodsynopsis>
                            <methodname>bool is_contained const</methodname>
                            <methodparam>
                                <funcparams/>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>get_state</title>
                        <para>Returns the required state of the state machine as a pointer. A
                            compile error will occur if the state is not to be found in the state
                            machine.</para>
                        <methodsynopsis>
                            <methodname>template &lt;class State> State* get_state</methodname>
                            <methodparam>
                                <funcparams/>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>get_state</title>
                        <para>Returns the required state of the state machine as a reference. A
                            compile error will occur if the state is not to be found in the state
                            machine.</para>
                        <methodsynopsis>
                            <methodname>template &lt;class State> State&amp; get_state</methodname>
                            <methodparam>
                                <funcparams/>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>is_flag_active</title>
                        <para>Returns true if the given flag is currently active. A flag is active
                            if the active state of one region is tagged with this flag (using OR as
                            BinaryOp) or active states of <emphasis role="underline">all</emphasis>
                            regions (using AND as BinaryOp)</para>
                        <methodsynopsis>
                            <methodname>template &lt;class Flag,class BinaryOp> bool
                                is_flag_active</methodname>
                            <methodparam>
                                <funcparams/>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>is_flag_active</title>
                        <para>Returns true if the given flag is currently active. A flag is active
                            if the active state of one region is tagged with this flag.</para>
                        <methodsynopsis>
                            <methodname>template &lt;class Flag> bool is_flag_active</methodname>
                            <methodparam>
                                <funcparams/>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>visit_current_states</title>
                        <para>Visits all active states and their substates. A state is visited using
                            the <code>accept</code> method without argument. The base class of all
                            states must provide an <code>accept_sig</code> type.</para>
                        <methodsynopsis>
                            <methodname>void visit_current_states</methodname>
                            <methodparam>
                                <funcparams/>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>visit_current_states</title>
                        <para>Visits all active states and their substates. A state is visited using
                            the <code>accept</code> method with arguments. The base class of all
                            states must provide an <code>accept_sig</code> type defining the
                            signature and thus the number and type of the parameters.</para>
                        <methodsynopsis>
                            <methodname>void visit_current_states</methodname>
                            <methodparam>
                                <funcparams>any-type param1, any-type param2,...</funcparams>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>defer_event</title>
                        <para> Defers the provided event. This method can be called only if at least
                            one state defers an event or if the state machine provides the
                                <code>activate_deferred_events</code>(see <link
                                xlink:href="examples/Orthogonal-deferred2.cpp">example</link>) type
                            either directly or using the deferred_events configuration of eUML
                                (<code>configure_ &lt;&lt; deferred_events</code>)</para>
                        <methodsynopsis>
                            <methodname>template &lt;class Event> void defer_event</methodname>
                            <methodparam>
                                <funcparams>Event const&amp;</funcparams>
                            </methodparam>
                        </methodsynopsis>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>Types</title>
                    <refsect3>
                        <title>nr_regions </title>
                        <para>The number of orthogonal regions contained in the state machine</para>
                    </refsect3>
                    <refsect3>
                        <title>entry_pt</title>
                        <para>This nested type provides the necessary typedef for entry point
                            pseudostates.
                                <code>state_machine&lt;...>::entry_pt&lt;state_name></code> is a
                            transition's valid target inside the containing state machine's
                            transition table.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>entry_pt</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>exit_pt</title>
                        <para>This nested type provides the necessary typedef for exit point
                            pseudostates. <code>state_machine&lt;...>::exit_pt&lt;state_name></code>
                            is a transition's valid source inside the containing state machine's
                            transition table.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>exit_pt</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>direct</title>
                        <para>This nested type provides the necessary typedef for an explicit entry
                            inside a submachine.
                                <code>state_machine&lt;...>::direct&lt;state_name></code> is a
                            transition's valid target inside the containing state machine's
                            transition table.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>direct</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>stt</title>
                        <para>Calling state_machine&lt;frontend>::stt returns a mpl::vector
                            containing the transition table of the state machine. This type can then
                            be used with generate_state_set or generate_event_set.</para>
                    </refsect3>
                </refsect2>
            </refsect1>
            <refsect1>
                <title>args.hpp</title>
                <para>This header provides one type, args. which provides the necessary types for a
                    visitor implementation.</para>
            </refsect1>
            <refsect1>
                <title><command xml:id="history-interface"/>msm/back/history_policies.hpp</title>
                <para>This header provides the out-of-the-box history policies supported by MSM.
                    There are 3 such policies.</para>
                <refsect2>
                    <title>Every history policy must implement the following methods: </title>
                    <refsect3>
                        <title> set_initial_states </title>
                        <para> This method is called by msm::back::state_machine when constructed.
                            It gives the policy a chance to save the ids of all initial states
                            (passed as array).</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>void set_initial_states</funcdef>
                                <paramdef>
                                    <funcparams>int* const</funcparams>
                                </paramdef>
                            </funcprototype>
                        </funcsynopsis>
                    </refsect3>
                    <refsect3>
                        <title> history_exit </title>
                        <para>This method is called by msm::back::state_machine when the submachine
                            is exited. It gives the policy a chance to remember the ids of the last
                            active substates of this submachine (passed as array).</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>void history_exit</funcdef>
                                <paramdef>
                                    <funcparams>int* const</funcparams>
                                </paramdef>
                            </funcprototype>
                        </funcsynopsis>
                    </refsect3>
                    <refsect3>
                        <title> history_entry </title>
                        <para>This method is called by msm::back::state_machine when the submachine
                            is entered. It gives the policy a chance to set the active states
                            according to the policy's aim. The policy gets as parameter the event
                            which activated the submachine and returns an array of active states
                            ids.</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class Event> int* const history_exit</funcdef>
                                <paramdef>
                                    <funcparams>Event const&amp;</funcparams>
                                </paramdef>
                            </funcprototype>
                        </funcsynopsis>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>Out-of-the-box policies: </title>
                    <refsect3>
                        <title>NoHistory</title>
                        <para>This policy is the default used by state_machine. No active state of a
                            submachine is remembered and at every new activation of the submachine,
                            the initial state(s) are activated. </para>
                    </refsect3>
                    <refsect3>
                        <title>AlwaysHistory</title>
                        <para>This policy is a non-UML-standard extension. The active state(s) of a
                            submachine is (are) always remembered at every new activation of the
                            submachine. </para>
                    </refsect3>
                    <refsect3>
                        <title>ShallowHistory</title>
                        <para>This policy activates the active state(s) of a submachine if the event
                            is found in the policy's event list. </para>
                    </refsect3>
                </refsect2>
            </refsect1>
            <refsect1>
                <title>msm/back/default_compile_policy.hpp</title>
                <para>This header contains the definition of favor_runtime_speed. This policy has
                    two settings:<itemizedlist>
                        <listitem>
                            <para>Submachines dispatch faster because their transitions are added
                                into their containing machine's transition table instead of simply
                                forwarding events.</para>
                        </listitem>
                        <listitem>
                            <para>It solves transition conflicts at compile-time</para>
                        </listitem>
                    </itemizedlist></para>
            </refsect1>
            <refsect1>
                <title>msm/back/favor_compile_time.hpp</title>
                <para>This header contains the definition of favor_compile_time. This policy has two settings:<itemizedlist>
                        <listitem>
                            <para>Submachines dispatch is slower because all events, even those with
                                no dispatch chance, are forwarded to submachines. In exchange, no
                                row is added into the containing machine's transition table, which
                                reduces compile-time.</para>
                        </listitem>
                        <listitem>
                            <para>It solves transition conflicts at run-time.</para>
                        </listitem>
                    </itemizedlist></para>
            </refsect1>
            <refsect1>
                <title>msm/back/metafunctions.hpp </title>
                <para>This header contains metafunctions for use by the library. Three metafunctions
                    can be useful for the user:<itemizedlist>
                        <listitem>
                            <para><code>generate_state_set&lt; stt ></code>: generates the list of
                                all states referenced by the transition table stt. If stt is a
                                recursive table (generated by
                                    <code>recursive_get_transition_table</code>), the metafunction
                                finds recursively all states of the submachines. A non-recursive
                                table can be obtained with some_backend_fsm::stt.</para>
                        </listitem>
                        <listitem>
                            <para><code>generate_event_set&lt; stt></code>: generates the list of
                                all events referenced by the transition table stt. If stt is a
                                recursive table (generated by
                                    <code>recursive_get_transition_table</code>), the metafunction
                                finds recursively all events of the submachines. A non-recursive
                                table can be obtained with some_backend_fsm::stt.</para>
                        </listitem>
                        <listitem>
                            <para><code>recursive_get_transition_table&lt;fsm></code>: recursively
                                extends the transition table of the state machine fsm with tables
                                from the submachines.</para>
                        </listitem>
                    </itemizedlist></para>
            </refsect1>
            <refsect1>
                <title>msm/back/tools.hpp </title>
                <para> This header contains a few metaprogramming tools to get some information out
                    of a state machine.</para>
                <refsect2>
                    <title>fill_state_names </title>
                    <refsect3>
                        <title>attributes </title>
                        <para> fill_state_names has for attribute:<itemizedlist>
                                <listitem>
                                    <para><code>char const** m_names</code>: an already allocated
                                        array of const char* where the typeid-generated names of a
                                        state machine states will be witten.</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>constructor </title>
                        <constructorsynopsis>
                            <methodparam>
                                <funcparams>char const** names_to_fill</funcparams>
                            </methodparam>
                        </constructorsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>usage</title>
                        <para> fill_state_names is made for use in a mpl::for_each iterating on a
                            state list and writing inside a pre-allocated array the state names.
                            Example:</para>
                        <programlisting>typedef some_fsm::stt Stt;
typedef msm::back::generate_state_set&lt;Stt>::type all_states; //states
static char const* state_names[mpl::size&lt;all_states>::value];
// array to fill with names
// fill the names of the states defined in the state machine
mpl::for_each&lt;all_states,boost::msm::wrap&lt;mpl::placeholders::_1> > 
    (msm::back::fill_state_names&lt;Stt>(state_names));
// display all active states
for (unsigned int i=0;i&lt;some_fsm::nr_regions::value;++i)
{
    std::cout &lt;&lt; " -> " 
              &lt;&lt; state_names[my_fsm_instance.current_state()[i]] 
              &lt;&lt; std::endl;
}</programlisting>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>get_state_name </title>
                    <refsect3>
                        <title> attributes </title>
                        <para>get_state_name has for attributes:<itemizedlist>
                                <listitem>
                                    <para>std::string&amp; m_name: the return value of the
                                        iteration</para>
                                </listitem>
                                <listitem>
                                    <para>int m_state_id: the searched state's id</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>constructor</title>
                        <para>The constructor takes as argument a reference to the string to fill
                            with the state name and the id which must be searched.</para>
                        <constructorsynopsis>
                            <methodparam>
                                <funcparams>string&amp; name_to_fill,int state_id</funcparams>
                            </methodparam>
                        </constructorsynopsis>
                    </refsect3>
                    <refsect3>
                        <title> usage</title>
                        <para>This type is made for the same search as in the previous example,
                            using a mpl::for_each to iterate on states. After the iteration, the
                            state name reference has been set.</para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>display_type </title>
                    <refsect3>
                        <title> attributes </title>
                        <para>none</para>
                    </refsect3>
                    <refsect3>
                        <title> usage</title>
                        <para>Reusing the state list from the previous example, we can output all
                            state names:</para>
                        <para><code>mpl::for_each&lt;all_states,boost::msm::wrap&lt;mpl::placeholders::_1>
                                >(msm::back::display_type ());</code></para>
                    </refsect3>
                </refsect2>
            </refsect1>
        </refentry>
        <refentry>
            <refnamediv>
                <refname>Front-end</refname>
                <refpurpose>The front-end headers</refpurpose>
            </refnamediv>
            <refsect1>
                <title>msm/front/common_states.hpp</title>
                <para>This header contains the predefined types to serve as base for states or state machines:<itemizedlist>
                        <listitem>
                            <para>default_base_state: non-polymorphic empty type.</para>
                        </listitem>
                        <listitem>
                            <para>polymorphic_state: type with a virtual destructor, which makes all
                                states polymorphic.</para>
                        </listitem>
                    </itemizedlist></para>
            </refsect1>
            <refsect1>
                <title>msm/front/completion_event.hpp</title>
                <para>This header contains one type, <code>none</code>. This type has several
                    meanings inside a transition table:<itemizedlist>
                        <listitem>
                            <para>as action or guard: that there is no action or guard</para>
                        </listitem>
                        <listitem>
                            <para>as target state: that the transition is an internal
                                transition</para>
                        </listitem>
                        <listitem>
                            <para>as event: the transition is an anonymous (completion)
                                transition</para>
                        </listitem>
                    </itemizedlist></para>
            </refsect1>
            <refsect1>
                <title>msm/front/functor_row.hpp</title>
                <para>This header implements the functor front-end's transitions and helpers.</para>
                <refsect2>
                    <title>Row</title>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template &lt;class Source,class Event,class Target,class
                                    Action,class Guard> Row</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>tags</title>
                        <para>row_type_tag is defined differently for every specialization:<itemizedlist>
                                <listitem>
                                    <para>all 5 template parameters means a normal transition with
                                        action and guard: <code>typedef row_tag
                                        row_type_tag;</code></para>
                                </listitem>
                                <listitem>
                                    <para>Row&lt;Source,Event,Target,none,none> a normal transition
                                        without action or guard: <code>typedef _row_tag
                                            row_type_tag;</code></para>
                                </listitem>
                                <listitem>
                                    <para>Row&lt;Source,Event,Target,Action,none> a normal
                                        transition without guard: <code>typedef a_row_tag
                                            row_type_tag;</code></para>
                                </listitem>
                                <listitem>
                                    <para>Row&lt;Source,Event,Target,none,Guard> a normal transition
                                        without action: <code>typedef g_row_tag
                                        row_type_tag;</code></para>
                                </listitem>
                                <listitem>
                                    <para>Row&lt;Source,Event,none,Action,none> an internal
                                        transition without guard: <code>typedef a_irow_tag
                                            row_type_tag;</code></para>
                                </listitem>
                                <listitem>
                                    <para>Row&lt;Source,Event,none,none,Guard> an internal
                                        transition without action: <code>typedef g_irow_tag
                                            row_type_tag;</code></para>
                                </listitem>
                                <listitem>
                                    <para>Row&lt;Source,Event,none,none,Guard> an internal
                                        transition with action and guard: <code>typedef irow_tag
                                            row_type_tag;</code></para>
                                </listitem>
                                <listitem>
                                    <para>Row&lt;Source,Event,none,none,none> an internal transition
                                        without action or guard: <code>typedef _irow_tag
                                            row_type_tag;</code></para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>methods</title>
                        <para>Like any other front-end, Row implements the two necessary static
                            functions for action and guard call. Each function receives as parameter
                            the (deepest-level) state machine processsing the event, the event
                            itself, the source and target states and all the states contained in a
                            state machine.</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class Fsm,class SourceState,class TargetState,
                                    class AllStates> static void action_call</funcdef>
                                <paramdef>
                                    <funcparams>Fsm&amp; fsm,Event const&amp;
                                        evt,SourceState&amp;,TargetState,AllStates&amp;</funcparams>
                                </paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class Fsm,class SourceState,class TargetState,
                                    class AllStates> static bool guard_call</funcdef>
                                <paramdef>
                                    <funcparams>Fsm&amp; fsm,Event const&amp;
                                        evt,SourceState&amp;,TargetState,AllStates&amp;</funcparams>
                                </paramdef>
                            </funcprototype>
                        </funcsynopsis>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>Internal</title>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template &lt;class Event,class Action,class Guard>
                                    Internal</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>tags</title>
                        <para>row_type_tag is defined differently for every specialization:<itemizedlist>
                                <listitem>
                                    <para>all 3 template parameters means an internal transition
                                        with action and guard: <code>typedef sm_i_row_tag
                                            row_type_tag;</code></para>
                                </listitem>
                                <listitem>
                                    <para>Internal&lt;Event,none,none> an internal transition
                                        without action or guard: <code>typedef sm__i_row_tag
                                            row_type_tag;</code></para>
                                </listitem>
                                <listitem>
                                    <para>Internal&lt;Event,Action,none> an internal transition
                                        without guard: <code>typedef sm_a_i_row_tag
                                            row_type_tag;</code></para>
                                </listitem>
                                <listitem>
                                    <para>Internal&lt;Event,none,Guard> an internal transition
                                        without action: <code>typedef sm_g_i_row_tag
                                            row_type_tag;</code></para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>methods</title>
                        <para>Like any other front-end, Internal implements the two necessary static
                            functions for action and guard call. Each function receives as parameter
                            the (deepest-level) state machine processsing the event, the event
                            itself, the source and target states and all the states contained in a
                            state machine.</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class Fsm,class SourceState,class TargetState,
                                    class AllStates> static void action_call</funcdef>
                                <paramdef>
                                    <funcparams>Fsm&amp; fsm,Event const&amp;
                                        evt,SourceState&amp;,TargetState,AllStates&amp;</funcparams>
                                </paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class Fsm,class SourceState,class TargetState,
                                    class AllStates> static bool guard_call</funcdef>
                                <paramdef>
                                    <funcparams>Fsm&amp; fsm,Event const&amp;
                                        evt,SourceState&amp;,TargetState,AllStates&amp;</funcparams>
                                </paramdef>
                            </funcprototype>
                        </funcsynopsis>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>ActionSequence_</title>
                    <para>This functor calls every element of the template Sequence (which are also
                        callable functors) in turn. It is also the underlying implementation of the
                        eUML sequence grammar (action1,action2,...).</para>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template &lt;class Sequence> ActionSequence_</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>methods</title>
                        <para>This helper functor is made for use in a transition table and in a
                            state behavior and therefore implements an operator() with 3 and with 4
                            arguments:</para>
                        <para>
                            <funcsynopsis>
                                <funcprototype>
                                    <funcdef>template &lt;class Evt,class Fsm,class
                                        SourceState,class TargetState> operator()</funcdef>
                                    <paramdef>Evt const&amp; ,Fsm&amp; ,SourceState&amp;
                                        ,TargetState&amp; </paramdef>
                                </funcprototype>
                            </funcsynopsis>
                        </para>
                        <para>
                            <funcsynopsis>
                                <funcprototype>
                                    <funcdef>template &lt;class Evt,class Fsm,class State>
                                        operator()</funcdef>
                                    <paramdef>Evt const&amp;, Fsm&amp;, State&amp;</paramdef>
                                </funcprototype>
                            </funcsynopsis>
                        </para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>Defer</title>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>Defer</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>methods</title>
                        <para>This helper functor is made for use in a transition table and
                            therefore implements an operator() with 4 arguments:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class Evt,class Fsm,class SourceState,class
                                    TargetState> operator()</funcdef>
                                <paramdef>Evt const&amp;, Fsm&amp; , SourceState&amp;,
                                    TargetState&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                    </refsect3>
                </refsect2>
            </refsect1>
            <refsect1>
                <title>msm/front/internal_row.hpp</title>
                <para>This header implements the internal transition rows for use inside an
                    internal_transition_table. All these row types have no source or target state,
                    as the backend will recognize internal transitions from this
                    internal_transition_table.</para>
                <refsect2>
                    <title>methods</title>
                    <para>Like any other front-end, the following transition row types implements
                        the two necessary static functions for action and guard call. Each function
                        receives as parameter the (deepest-level) state machine processsing the
                        event, the event itself, the source and target states and all the states
                        contained in a state machine.</para>
                    <funcsynopsis>
                        <funcprototype>
                            <funcdef>template &lt;class Fsm,class SourceState,class TargetState,
                                class AllStates> static void action_call</funcdef>
                            <paramdef>
                                <funcparams>Fsm&amp; fsm,Event const&amp;
                                    evt,SourceState&amp;,TargetState,AllStates&amp;</funcparams>
                            </paramdef>
                        </funcprototype>
                    </funcsynopsis>
                    <funcsynopsis>
                        <funcprototype>
                            <funcdef>template &lt;class Fsm,class SourceState,class TargetState,
                                class AllStates> static bool guard_call</funcdef>
                            <paramdef>
                                <funcparams>Fsm&amp; fsm,Event const&amp;
                                    evt,SourceState&amp;,TargetState,AllStates&amp;</funcparams>
                            </paramdef>
                        </funcprototype>
                    </funcsynopsis>
                </refsect2>
                <refsect2>
                    <title>a_internal</title>
                    <refsect3>
                        <title>definition</title>
                        <para>This is an internal transition with an action called during the
                            transition.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt; class Event, class CalledForAction, void
                                    (CalledForAction::*action)(Event const&amp;)>
                                    a_internal</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>template parameters</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the internal
                                        transition.</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForAction: the type on which the action method will
                                        be called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>action: a pointer to the method which CalledForAction
                                        provides.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>g_internal</title>
                    <para>This is an internal transition with a guard called before the transition
                        and allowing the transition if returning true.</para>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt; class Event, class CalledForGuard, bool
                                    (CalledForGuard::*guard)(Event const&amp;)>
                                    g_internal</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>template parameters</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the internal
                                        transition.</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForGuard: the type on which the guard method will be
                                        called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>guard: a pointer to the method which CalledForGuard
                                        provides.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>internal</title>
                    <para>This is an internal transition with a guard called before the transition
                        and allowing the transition if returning true. It also calls an action
                        called during the transition.</para>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt; class Event, class CalledForAction, void
                                    (CalledForAction::*action)(Event const&amp;), class
                                    CalledForGuard, bool (CalledForGuard::*guard)(Event const&amp;)>
                                    internal</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>template parameters</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the internal transition</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForAction: the type on which the action method will
                                        be called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>action: a pointer to the method which CalledForAction
                                        provides.</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForGuard: the type on which the guard method will be
                                        called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>guard: a pointer to the method which CalledForGuard
                                        provides.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>_internal</title>
                    <para>This is an internal transition without action or guard. This is equivalent
                        to an explicit "ignore event".</para>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt; class Event > _internal</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>template parameters</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the internal
                                        transition.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                </refsect2>
            </refsect1>
            <refsect1>
                <title>msm/front/row2.hpp</title>
                <para>This header contains the variants of row2, which are an extension of the
                    standard row transitions for use in the transition table. They offer the
                    possibility to define action and guard not only in the state machine, but in any
                    state of the state machine. They can also be used in internal transition tables
                    through their irow2 variants.</para>
                <refsect2>
                    <title>methods</title>
                    <para>Like any other front-end, the following transition row types implements
                        the two necessary static functions for action and guard call. Each function
                        receives as parameter the (deepest-level) state machine processsing the
                        event, the event itself, the source and target states and all the states
                        contained in a state machine.</para>
                    <funcsynopsis>
                        <funcprototype>
                            <funcdef>template &lt;class Fsm,class SourceState,class TargetState,
                                class AllStates> static void action_call</funcdef>
                            <paramdef>
                                <funcparams>Fsm&amp; fsm,Event const&amp;
                                    evt,SourceState&amp;,TargetState,AllStates&amp;</funcparams>
                            </paramdef>
                        </funcprototype>
                    </funcsynopsis>
                    <funcsynopsis>
                        <funcprototype>
                            <funcdef>template &lt;class Fsm,class SourceState,class TargetState,
                                class AllStates> static bool guard_call</funcdef>
                            <paramdef>
                                <funcparams>Fsm&amp; fsm,Event const&amp;
                                    evt,SourceState&amp;,TargetState,AllStates&amp;</funcparams>
                            </paramdef>
                        </funcprototype>
                    </funcsynopsis>
                </refsect2>
                <refsect2>
                    <title>_row2</title>
                    <para>This is a transition without action or guard. The state machine only
                        changes active state.</para>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt; class Source, class Event, class Target >
                                    _row2</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>template parameters</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Target: the target state of the transition.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>a_row2</title>
                    <para>This is a transition with action and without guard.</para>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt; class Source, class Event, class Target,
                                </classname>
                            </ooclass>
                        </classsynopsis>
                        <classsynopsis>
                            <ooclass>
                                <classname>class CalledForAction, void
                                    (CalledForAction::*action)(Event const&amp;) > _row2</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>template parameters</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Target: the target state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForAction: the type on which the action method will
                                        be called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>action: a pointer to the method which CalledForAction
                                        provides.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>g_row2</title>
                    <para>This is a transition with guard and without action.</para>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt; class Source, class Event, class Target,
                                </classname>
                            </ooclass>
                        </classsynopsis>
                        <classsynopsis>
                            <ooclass>
                                <classname>class CalledForGuard, bool (CalledForGuard::*guard)(Event
                                    const&amp;) > _row2</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>template parameters</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Target: the target state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForGuard: the type on which the guard method will be
                                        called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>guard: a pointer to the method which CalledForGuard
                                        provides.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>row2</title>
                    <para>This is a transition with guard and action.</para>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt; class Source, class Event, class Target,
                                </classname>
                            </ooclass>
                        </classsynopsis>
                        <classsynopsis>
                            <ooclass>
                                <classname>class CalledForAction, void
                                    (CalledForAction::*action)(Event const&amp;), </classname>
                            </ooclass>
                        </classsynopsis>
                        <classsynopsis>
                            <ooclass>
                                <classname>class CalledForGuard, bool (CalledForGuard::*guard)(Event
                                    const&amp;) > _row2</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>template parameters</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Target: the target state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForAction: the type on which the action method will
                                        be called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>action: a pointer to the method which CalledForAction
                                        provides.</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForGuard: the type on which the guard method will be
                                        called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>guard: a pointer to the method which CalledForGuard
                                        provides.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>a_irow2</title>
                    <para>This is an internal transition for use inside a transition table, with
                        action and without guard.</para>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt; class Source, class Event, </classname>
                            </ooclass>
                        </classsynopsis>
                        <classsynopsis>
                            <ooclass>
                                <classname>class CalledForAction, void
                                    (CalledForAction::*action)(Event const&amp;) > _row2</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>template parameters</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForAction: the type on which the action method will
                                        be called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>action: a pointer to the method which CalledForAction
                                        provides.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>g_irow2</title>
                    <para>This is an internal transition for use inside a transition table, with
                        guard and without action.</para>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt; class Source, class Event, </classname>
                            </ooclass>
                        </classsynopsis>
                        <classsynopsis>
                            <ooclass>
                                <classname>class CalledForGuard, bool (CalledForGuard::*guard)(Event
                                    const&amp;) > _row2</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>template parameters</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForGuard: the type on which the guard method will be
                                        called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>guard: a pointer to the method which CalledForGuard
                                        provides.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>irow2</title>
                    <para>This is an internal transition for use inside a transition table, with
                        guard and action.</para>
                    <refsect3>
                        <title>definition</title>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt; class Source, class Event, </classname>
                            </ooclass>
                        </classsynopsis>
                        <classsynopsis>
                            <ooclass>
                                <classname>class CalledForAction, void
                                    (CalledForAction::*action)(Event const&amp;), </classname>
                            </ooclass>
                        </classsynopsis>
                        <classsynopsis>
                            <ooclass>
                                <classname>class CalledForGuard, bool (CalledForGuard::*guard)(Event
                                    const&amp;) > _row2</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>template parameters</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForAction: the type on which the action method will
                                        be called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>action: a pointer to the method which CalledForAction
                                        provides.</para>
                                </listitem>
                                <listitem>
                                    <para>CalledForGuard: the type on which the guard method will be
                                        called. It can be either a state of the containing state
                                        machine or the state machine itself.</para>
                                </listitem>
                                <listitem>
                                    <para>guard: a pointer to the method which CalledForGuard
                                        provides.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                </refsect2>
            </refsect1>
            <refsect1>
                <title>msm/front/state_machine_def.hpp</title>
                <para>This header provides the implementation of the <command
                        xlink:href="#basic-front-end">basic front-end</command>. It contains one
                    type, <code>state_machine_def</code></para>
                <refsect2>
                    <title>state_machine_def definition</title>
                    <para>This type is the basic class for a basic (or possibly any other)
                        front-end. It provides the standard row types (which includes internal
                        transitions) and a default implementation of the required methods and
                        typedefs.</para>
                    <classsynopsis>
                        <ooclass>
                            <classname>template &lt;class Derived,class BaseState =
                                default_base_state> state_machine_def</classname>
                        </ooclass>
                    </classsynopsis>
                    <refsect3>
                        <title>typedefs</title>
                        <para>
                            <itemizedlist>
                                <listitem>
                                    <para>flag_list: by default, no flag is set in the state
                                        machine</para>
                                </listitem>
                                <listitem>
                                    <para>deferred_events: by default, no event is deferred.</para>
                                </listitem>
                                <listitem>
                                    <para>configuration: by default, no configuration customization
                                        is done.</para>
                                </listitem>
                            </itemizedlist>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>row methods</title>
                        <para>Like any other front-end, the following transition row types
                            implements the two necessary static functions for action and guard call.
                            Each function receives as parameter the (deepest-level) state machine
                            processsing the event, the event itself, the source and target states
                            and all the states contained in a state machine (ignored).</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class Fsm,class SourceState,class TargetState,
                                    class AllStates> static void action_call</funcdef>
                                <paramdef>
                                    <funcparams>Fsm&amp; fsm,Event const&amp;
                                        evt,SourceState&amp;,TargetState,AllStates&amp;</funcparams>
                                </paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class Fsm,class SourceState,class TargetState,
                                    class AllStates> static bool guard_call</funcdef>
                                <paramdef>
                                    <funcparams>Fsm&amp; fsm,Event const&amp;
                                        evt,SourceState&amp;,TargetState,AllStates&amp;</funcparams>
                                </paramdef>
                            </funcprototype>
                        </funcsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>a_row</title>
                        <para>This is a transition with action and without guard.</para>
                        <para><ooclass>
                                <classname>template&lt; class Source, class Event, class Target,
                                    void (Derived::*action)(Event const&amp;) > a_row</classname>
                            </ooclass><itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Target: the target state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>action: a pointer to the method provided by the concrete
                                        front-end (represented by <code>Derived</code>).</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>g_row</title>
                        <para>This is a transition with guard and without action.</para>
                        <para><ooclass>
                                <classname>template&lt; class Source, class Event, class Target,
                                    bool (Derived::*guard)(Event const&amp;) > g_row</classname>
                            </ooclass><itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Target: the target state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>guard: a pointer to the method provided by the concrete
                                        front-end (represented by <code>Derived</code>).</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>row</title>
                        <para>This is a transition with guard and action.</para>
                        <para><ooclass>
                                <classname>template&lt; class Source, class Event, class Target,
                                    void (Derived::*action)(Event const&amp;), bool
                                    (Derived::*guard)(Event const&amp;) > row</classname>
                            </ooclass><itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Target: the target state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>action: a pointer to the method provided by the concrete
                                        front-end (represented by <code>Derived</code>).</para>
                                </listitem>
                                <listitem>
                                    <para>guard: a pointer to the method provided by the concrete
                                        front-end (represented by <code>Derived</code>).</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>_row</title>
                        <para>This is a transition without action or guard. The state machine only
                            changes active state.</para>
                        <para><ooclass>
                                <classname>template&lt; class Source, class Event, class Target >
                                    _row</classname>
                            </ooclass><itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Target: the target state of the transition.</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>a_irow</title>
                        <para>This is an internal transition for use inside a transition table, with
                            action and without guard.</para>
                        <para><ooclass>
                                <classname>template&lt; class Source, class Event, void
                                    (Derived::*action)(Event const&amp;) > a_irow</classname>
                            </ooclass><itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>action: a pointer to the method provided by the concrete
                                        front-end (represented by <code>Derived</code>).</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>g_irow</title>
                        <para>This is an internal transition for use inside a transition table, with
                            guard and without action.</para>
                        <para><ooclass>
                                <classname>template&lt; class Source, class Event, bool
                                    (Derived::*guard)(Event const&amp;) > g_irow</classname>
                            </ooclass><itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>guard: a pointer to the method provided by the concrete
                                        front-end (represented by <code>Derived</code>).</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>irow</title>
                        <para>This is an internal transition for use inside a transition table, with
                            guard and action.</para>
                        <para><ooclass>
                                <classname>template&lt; class Source, class Event, void
                                    (Derived::*action)(Event const&amp;), bool
                                    (Derived::*guard)(Event const&amp;) > irow</classname>
                            </ooclass><itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>action: a pointer to the method provided by the concrete
                                        front-end (represented by <code>Derived</code>).</para>
                                </listitem>
                                <listitem>
                                    <para>guard: a pointer to the method provided by the concrete
                                        front-end (represented by <code>Derived</code>).</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>_irow</title>
                        <para>This is an internal transition without action or guard. As it does
                            nothing, it means "ignore event".</para>
                        <para><ooclass>
                                <classname>template&lt; class Source, class Event >
                                    _irow</classname>
                            </ooclass><itemizedlist>
                                <listitem>
                                    <para>Event: the event triggering the transition.</para>
                                </listitem>
                                <listitem>
                                    <para>Source: the source state of the transition.</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>methods</title>
                        <para><code>state_machine_def</code> provides a default implementation in
                            case of an event which cannot be processed by a state machine (no
                            transition found). The implementation is using a
                                <code>BOOST_ASSERT</code> so that the error will only be noticed in
                            debug mode. Overwrite this method in your implementation to change the
                            behavior.</para>
                        <para>
                            <funcsynopsis>
                                <funcprototype>
                                    <funcdef>template &lt;class Fsm,class Event> static void
                                        no_transition</funcdef>
                                    <paramdef>
                                        <funcparams>Event const&amp; ,Fsm&amp;, int
                                            state</funcparams>
                                    </paramdef>
                                </funcprototype>
                            </funcsynopsis>
                        </para>
                        <para><code>state_machine_def</code> provides a default implementation in
                            case an exception is thrown by a state (entry/exit) or transition
                            (action/guard) behavior. The implementation is using a
                                <code>BOOST_ASSERT</code> so that the error will only be noticed in
                            debug mode. Overwrite this method in your implementation to change the
                            behavior. This method will be called only if exception handling is not
                            deactivated (default) by defining
                            <code>has_no_message_queue</code>.</para>
                        <para>
                            <funcsynopsis>
                                <funcprototype>
                                    <funcdef>template &lt;class Fsm,class Event> static void
                                        exception_caught</funcdef>
                                    <paramdef>
                                        <funcparams>Event const&amp; ,Fsm&amp;,
                                            std::exception&amp;</funcparams>
                                    </paramdef>
                                </funcprototype>
                            </funcsynopsis>
                        </para>
                    </refsect3>
                </refsect2>
            </refsect1>
            <refsect1>
                <title>msm/front/states.hpp </title>
                <para>This header provides the different states (except state machines) for the
                    basic front-end (or mixed with other front-ends).</para>
                <refsect2>
                    <title>types</title>
                    <para>This header provides the following types:</para>
                    <refsect3>
                        <title>no_sm_ptr</title>
                        <para>deprecated: default policy for states. It means that states do not
                            need to save a pointer to their containing state machine.</para>
                    </refsect3>
                    <refsect3>
                        <title>sm_ptr</title>
                        <para>deprecated: state policy. It means that states need to save a pointer
                            to their containing state machine. When seeing this flag, the back-end
                            will call set_sm_ptr(fsm*) and give itself as argument.</para>
                    </refsect3>
                    <refsect3>
                        <title>state</title>
                        <para>Basic type for simple states. Inherit from this type to define a
                            simple state. The first argument is needed if you want your state (and
                            all others used in a concrete state machine) to inherit a basic type for
                            logging or providing a common behavior.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt;class Base = default_base_state,class
                                    SMPtrPolicy = no_sm_ptr> state</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>terminate_state</title>
                        <para>Basic type for terminate states. Inherit from this type to define a
                            terminate state. The first argument is needed if you want your state
                            (and all others used in a concrete state machine) to inherit a basic
                            type for logging or providing a common behavior.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt;class Base = default_base_state,class
                                    SMPtrPolicy = no_sm_ptr> terminate_state</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>interrupt_state</title>
                        <para>Basic type for interrupt states. Interrupt states prevent any further
                            event handling until EndInterruptEvent is sent. Inherit from this type
                            to define a terminate state. The first argument is the name of the event
                            ending the interrupt. The second argument is needed if you want your
                            state (and all others used in a concrete state machine) to inherit a
                            basic type for logging or providing a common behavior.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt;class EndInterruptEvent,class Base =
                                    default_base_state,</classname>
                            </ooclass>
                        </classsynopsis>
                        <classsynopsis>
                            <ooclass>
                                <classname>class SMPtrPolicy = no_sm_ptr>
                                    interrupt_state</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>explicit_entry</title>
                        <para>Inherit from this type <emphasis role="underline">in
                                addition</emphasis> to the desired state type to enable this state
                            for direct entering. The template parameter gives the region id of the
                            state (regions are numbered in the order of the
                                <code>initial_state</code> typedef).</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template &lt;int ZoneIndex=-1> explicit_entry</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>entry_pseudo_state</title>
                        <para>Basic type for entry pseudo states. Entry pseudo states are an
                            predefined entry into a submachine and connect two transitions. The
                            first argument is the id of the region entered by this state (regions
                            are numbered in the order of the <code>initial_state</code> typedef).
                            The second argument is needed if you want your state (and all others
                            used in a concrete state machine) to inherit a basic type for logging or
                            providing a common behavior.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt;int RegionIndex=-1,class Base =
                                    default_base_state,</classname>
                            </ooclass>
                        </classsynopsis>
                        <classsynopsis>
                            <ooclass>
                                <classname>class SMPtrPolicy = no_sm_ptr>
                                    entry_pseudo_state</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>exit_pseudo_state</title>
                        <para>Basic type for exit pseudo states. Exit pseudo states are an
                            predefined exit from a submachine and connect two transitions. The first
                            argument is the name of the event which will be "thrown" out of the exit
                            point. This event does not need to be the same as the one sent by the
                            inner region but must be convertible from it. The second argument is
                            needed if you want your state (and all others used in a concrete state
                            machine) to inherit a basic type for logging or providing a common
                            behavior.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template&lt;class Event,class Base =
                                    default_base_state,</classname>
                            </ooclass>
                        </classsynopsis>
                        <classsynopsis>
                            <ooclass>
                                <classname>class SMPtrPolicy = no_sm_ptr>
                                    exit_pseudo_state</classname>
                            </ooclass>
                        </classsynopsis>
                    </refsect3>
                </refsect2>
            </refsect1>
            <refsect1>
                <title>msm/front/euml/euml.hpp</title>
                <para>This header includes all of eUML except the STL functors.</para>
            </refsect1>
            <refsect1>
                <title>msm/front/euml/stl.hpp</title>
                <para>This header includes all the functors for STL support in eUML. These <command
                        xlink:href="#eUML-STL-all">tables</command> show a full description.</para>
            </refsect1>
            <refsect1>
                <title>msm/front/euml/algorithm.hpp</title>
                <para>This header includes all the functors for STL algorithms support in eUML.
                    These <command xlink:href="#eUML-STL-all">tables</command> show a full
                    description.</para>
            </refsect1>
            <refsect1>
                <title>msm/front/euml/iteration.hpp</title>
                <para>This header includes iteration functors for STL support in eUML. This <command
                        xlink:href="#eUML-STL-iteration">tables</command> shows a full
                    description.</para>
            </refsect1>
            <refsect1>
                <title>msm/front/euml/querying.hpp</title>
                <para>This header includes querying functors for STL support in eUML. This <command
                        xlink:href="#eUML-STL-querying">tables</command> shows a full
                    description.</para>
            </refsect1>
            <refsect1>
                <title>msm/front/euml/transformation.hpp</title>
                <para>This header includes transformation functors for STL support in eUML. This
                        <command xlink:href="#eUML-STL-transformation">tables</command> shows a full
                    description.</para>
            </refsect1>
            <refsect1>
                <title>msm/front/euml/container.hpp</title>
                <para>This header includes container functors for STL support in eUML (functors
                    calling container methods). This <command xlink:href="#eUML-STL-container"
                        >tables</command> shows a full description. It also provides npos for
                    strings.</para>
                <refsect2>
                    <title>Npos_&lt;container type></title>
                    <para>Functor returning npos for transition or state behaviors. Like all
                        constants, only the functor form exists, so parenthesis are necessary.
                        Example:</para>
                    <para><code>string_find_(event_(m_song),Char_&lt;'S'>(),Size_t_&lt;0>()) !=
                            Npos_&lt;string>() // compare result of string::find with
                        npos</code></para>
                </refsect2>
            </refsect1>
            <refsect1>
                <title>msm/front/euml/stt_grammar.hpp</title>
                <para>This header provides the transition table grammars. This includes internal
                    transition tables.</para>
                <refsect2>
                    <title>functions</title>
                    <refsect3>
                        <title>build_stt</title>
                        <para>The function build_stt evaluates the grammar-conform expression as
                            parameter. It returns a transition table, which is a mpl::vector of
                            transitions (rows) or, if the expression is ill-formed (does not match
                            the grammar), the type <code>invalid_type</code>, which will lead to a
                            compile-time static assertion when this transition table is passed to a
                            state machine. </para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template&lt;class Expr> [mpl::vector&lt;...> /
                                    msm::front::euml::invalid_type] build_stt</funcdef>
                                <paramdef>Expr const&amp; expr</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                    </refsect3>
                    <refsect3>
                        <title>build_internal_stt</title>
                        <para>The function build_internal_stt evaluates the grammar-conform
                            expression as parameter. It returns a transition table, which is a
                            mpl::vector of transitions (rows) or, if the expression is ill-formed
                            (does not match the grammar), the type <code>invalid_type</code>, which
                            will lead to a compile-time static assertion when this transition table
                            is passed to a state machine. </para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template&lt;class Expr> [mpl::vector&lt;...> /
                                    msm::front::euml::invalid_type] build_internal_stt</funcdef>
                                <paramdef>Expr const&amp; expr</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                    </refsect3>
                </refsect2>
                <refsect2>
                    <title>grammars</title>
                    <refsect3>
                        <title><command xml:id="reference-stt-grammar">transition
                            table</command></title>
                        <para>The transition table accepts the following grammar:</para>
                        <programlisting>Stt := Row | (Stt ',' Stt)
Row := (Target '==' (SourcePlusEvent)) /* first syntax*/
       | ( (SourcePlusEvent) '==' Target ) /* second syntax*/
       | (SourcePlusEvent) /* internal transitions */
SourcePlusEvent := (BuildSource '+' BuildEvent)/* standard transition*/ 
                   | (BuildSource) /* anonymous transition */
BuildSource := state_tag | (state_tag '/' Action) | (state_tag '[' Guard ']') 
            | (state_tag '[' Guard ']' '/' Action)
BuildEvent := event_tag | (event_tag '/' Action) | (event_tag '[' Guard ']') 
            | (event_tag '[' Guard ']' '/' Action)</programlisting>
                        <para>The grammars Action and Guard are defined in state_grammar.hpp and
                            guard_grammar.hpp respectively. state_tag and event_tag are inherited
                            from euml_state (or other state variants) and euml_event respectively.
                            For example, following declarations are possible:</para>
                        <programlisting>target == source + event [guard] / action,
source + event [guard] / action == target,
source + event [guard] / (action1,action2) == target,
target == source + event [guard] / (action1,action2),
target == source + event,
source + event == target,
target == source + event [guard],
source + event [guard] == target,
target == source + event / action,
source + event /action == target,
source / action == target, /*anonymous transition*/
target == source / action, /*anonymous transition*/
source + event /action, /* internal transition*/</programlisting>
                    </refsect3>
                    <refsect3>
                        <title>internal transition table</title>
                        <para>The internal transition table accepts the following grammar:</para>
                        <programlisting>IStt := BuildEvent | (IStt ',' IStt)</programlisting>
                        <para>BuildEvent being defined for both internal and standard transition
                            tables.</para>
                    </refsect3>
                </refsect2>
            </refsect1>
            <refsect1>
                <title>msm/front/euml/guard_grammar.hpp</title>
                <para>This header contains the <code>Guard</code> grammar used in the previous
                    section. This grammar is long but pretty simple:</para>
                <programlisting>Guard := action_tag | (Guard '&amp;&amp;' Guard) 
        | (Guard '||' Guard) | ... /* operators*/
        | (if_then_else_(Guard,Guard,Guard)) | (function (Action,...Action))</programlisting>
                <para>Most C++ operators are supported (address-of is not). With
                        <code>function</code> is meant any eUML predefined function or any self-made
                    (using <code>MSM_EUML_METHOD</code> or <code>MSM_EUML_FUNCTION</code>). Action
                    is a grammar defined in state_grammar.hpp.</para>
            </refsect1>
            <refsect1>
                <title>msm/front/euml/state_grammar.hpp</title>
                <para>This header provides the grammar for actions and the different grammars and
                    functions to build states using eUML.</para>
                <refsect2>
                    <title>action grammar</title>
                    <para>Like the guard grammar, this grammar supports relevant C++ operators and
                        eUML functions:</para>
                    <programlisting>Action := action_tag | (Action '+' Action) 
          | ('--' Action) | ... /* operators*/
          | if_then_else_(Guard,Action,Action) | if_then_(Action) 
          | while_(Guard,Action) 
          | do_while_(Guard,Action) | for_(Action,Guard,Action,Action) 
          | (function(Action,...Action))
ActionSequence := Action | (Action ',' Action)</programlisting>
                    <para>Relevant operators are: ++ (post/pre), -- (post/pre), dereferencing, +
                        (unary/binary), - (unary/binary), *, /, %, &amp;(bitwise), | (bitwise),
                        ^(bitwise), +=, -=, *=, /=, %=, &lt;&lt;=, >>=, &lt;&lt;, >>, =, [].</para>
                </refsect2>
                <refsect2>
                    <title>attributes</title>
                    <para>This grammar is used to add attributes to states (or state machines) or
                        events: It evaluates to a fusion::map. You can use two forms:<itemizedlist>
                            <listitem>
                                <para><code>attributes_ &lt;&lt; no_attributes_</code></para>
                            </listitem>
                            <listitem>
                                <para><code>attributes_ &lt;&lt; attribute_1 &lt;&lt; ... &lt;&lt;
                                        attribute_n</code></para>
                            </listitem>
                        </itemizedlist></para>
                    <para>Attributes can be of any default-constructible type (fusion
                        requirement).</para>
                </refsect2>
                <refsect2>
                    <title>configure</title>
                    <para>This grammar also has two forms:<itemizedlist>
                            <listitem>
                                <para><code>configure_ &lt;&lt; no_configure_</code></para>
                            </listitem>
                            <listitem>
                                <para><code>configure_ &lt;&lt; type_1 &lt;&lt; ... &lt;&lt;
                                        type_n</code></para>
                            </listitem>
                        </itemizedlist></para>
                    <para>This grammar is used to create inside one syntax:<itemizedlist>
                            <listitem>
                                <para>flags: <code>configure_ &lt;&lt; some_flag</code> where
                                    some_flag inherits from <code>euml_flag&lt;some_flag></code> or
                                    is defined using BOOST_MSM_EUML_FLAG.</para>
                            </listitem>
                            <listitem>
                                <para>deferred events: <code>configure_ &lt;&lt; some_event</code>
                                    where some_event inherits from
                                        <code>euml_event&lt;some_event></code> or is defined using
                                    BOOST_MSM_EUML_EVENT or
                                    BOOST_MSM_EUML_EVENT_WITH_ATTRIBUTES.</para>
                            </listitem>
                            <listitem>
                                <para>configuration (message queue, manual deferring, exception
                                    handling): <code>configure_ &lt;&lt; some_config</code> where
                                    some_config inherits from
                                        <code>euml_config&lt;some_config></code>. At the moment,
                                    three predefined objects exist (in msm//front/euml/common.hpp):<itemizedlist>
                                        <listitem>
                                            <para>no_exception: disable catching exceptions</para>
                                        </listitem>
                                        <listitem>
                                            <para>no_msg_queue: disable message queue</para>
                                        </listitem>
                                        <listitem>
                                            <para>deferred_events: manually enable handling of
                                                deferred events</para>
                                        </listitem>
                                    </itemizedlist></para>
                            </listitem>
                        </itemizedlist></para>
                </refsect2>
                <refsect2>
                    <title>initial states</title>
                    <para>The grammar to define initial states for a state machine is: <code>init_
                            &lt;&lt; state_1 &lt;&lt; ... &lt;&lt; state_n</code> where
                        state_1...state_n inherit from euml_state or is defined using
                        BOOST_MSM_EUML_STATE, BOOST_MSM_EUML_INTERRUPT_STATE,
                        BOOST_MSM_EUML_TERMINATE_STATE, BOOST_MSM_EUML_EXPLICIT_ENTRY_STATE,
                        BOOST_MSM_EUML_ENTRY_STATE or BOOST_MSM_EUML_EXIT_STATE.</para>
                </refsect2>
                <refsect2>
                    <title>functions</title>
                    <refsect3>
                        <title>build_sm</title>
                        <para>This function has several overloads. The return type is not relevant
                            to you as only decltype (return type) is what one needs.</para>
                        <para>Defines a state machine without entry or exit:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Stt,class Init>
                                    func_state_machine&lt;...> build_sm</funcdef>
                                <paramdef>Stt ,Init</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines a state machine with entry behavior:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Stt,class Init,class
                                    Expr1> func_state_machine&lt;...> build_sm</funcdef>
                                <paramdef>Stt ,Init,Expr1 const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines a state machine with entry and exit behaviors:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Stt,class Init,class
                                    Expr1, class Expr2> func_state_machine&lt;...>
                                    build_sm</funcdef>
                                <paramdef>Stt ,Init,Expr1 const&amp;,Expr2 const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines a state machine with entry, exit behaviors and
                            attributes:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Stt,class Init,class
                                    Expr1, class Expr2, class Attributes> func_state_machine&lt;...>
                                    build_sm</funcdef>
                                <paramdef>Stt ,Init,Expr1 const&amp;, Expr2 const&amp;, Attributes
                                    const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines a state machine with entry, exit behaviors, attributes and
                            configuration (deferred events, flags):</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Stt,class Init,class
                                    Expr1, class Expr2, class Attributes, class Configure>
                                    func_state_machine&lt;...> build_sm</funcdef>
                                <paramdef>Stt ,Init,Expr1 const&amp;, Expr2 const&amp;, Attributes
                                    const&amp;, Configure const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines a state machine with entry, exit behaviors, attributes,
                            configuration (deferred events, flags) and a base state:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Stt,class Init,class
                                    Expr1, class Expr2, class Attributes, class Configure, class
                                    Base> func_state_machine&lt;...> build_sm</funcdef>
                                <paramdef>Stt ,Init,Expr1 const&amp;, Expr2 const&amp;, Attributes
                                    const&amp;, Configure const&amp;, Base</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Notice that this function requires the extra parameter class
                            StateNameTag to disambiguate state machines having the same parameters
                            but still being different.</para>
                    </refsect3>
                    <refsect3>
                        <title>build_state</title>
                        <para>This function has several overloads. The return type is not relevant
                            to you as only decltype (return type) is what one needs.</para>
                        <para>Defines a simple state without entry or exit:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>func_state&lt;class StateNameTag,...> build_state</funcdef>
                                <paramdef/>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines a simple state with entry behavior:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Expr1>
                                    func_state&lt;...> build_state</funcdef>
                                <paramdef>Expr1 const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines a simple state with entry and exit behaviors:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Expr1, class Expr2>
                                    func_state&lt;...> build_state</funcdef>
                                <paramdef>Expr1 const&amp;,Expr2 const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines a simple state with entry, exit behaviors and
                            attributes:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Expr1, class Expr2,
                                    class Attributes> func_state&lt;...> build_state</funcdef>
                                <paramdef>Expr1 const&amp;, Expr2 const&amp;, Attributes
                                    const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines a simple state with entry, exit behaviors, attributes and
                            configuration (deferred events, flags):</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Expr1, class Expr2,
                                    class Attributes, class Configure> func_state&lt;...>
                                    build_state</funcdef>
                                <paramdef>Expr1 const&amp;, Expr2 const&amp;, Attributes const&amp;,
                                    Configure const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines a simple state with entry, exit behaviors, attributes,
                            configuration (deferred events, flags) and a base state:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Expr1, class Expr2,
                                    class Attributes, class Configure, class Base>
                                    func_state&lt;...> build_state</funcdef>
                                <paramdef>Expr1 const&amp;, Expr2 const&amp;, Attributes const&amp;,
                                    Configure const&amp;, Base</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Notice that this function requires the extra parameter class
                            StateNameTag to disambiguate states having the same parameters but still
                            being different.</para>
                    </refsect3>
                    <refsect3>
                        <title>build_terminate_state</title>
                        <para>This function has the same overloads as build_state.</para>
                    </refsect3>
                    <refsect3>
                        <title>build_interrupt_state</title>
                        <para>This function has several overloads. The return type is not relevant
                            to you as only decltype (return type) is what one needs.</para>
                        <para>Defines an interrupt state without entry or exit:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class EndInterruptEvent>
                                    func_state&lt;...> build_interrupt_state</funcdef>
                                <paramdef>EndInterruptEvent const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an interrupt state with entry behavior:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class
                                    EndInterruptEvent,class Expr1> func_state&lt;...>
                                    build_interrupt_state</funcdef>
                                <paramdef>EndInterruptEvent const&amp;,Expr1 const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an interrupt state with entry and exit behaviors:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class
                                    EndInterruptEvent,class Expr1, class Expr2> func_state&lt;...>
                                    build_interrupt_state</funcdef>
                                <paramdef>EndInterruptEvent const&amp;,Expr1 const&amp;,Expr2
                                    const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an interrupt state with entry, exit behaviors and
                            attributes:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class
                                    EndInterruptEvent,class Expr1, class Expr2, class Attributes>
                                    func_state&lt;...> build_interrupt_state</funcdef>
                                <paramdef>EndInterruptEvent const&amp;,Expr1 const&amp;, Expr2
                                    const&amp;, Attributes const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an interrupt state with entry, exit behaviors, attributes and
                            configuration (deferred events, flags):</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class
                                    EndInterruptEvent,class Expr1, class Expr2, class Attributes,
                                    class Configure> func_state&lt;...>
                                    build_interrupt_state</funcdef>
                                <paramdef>EndInterruptEvent const&amp;,Expr1 const&amp;, Expr2
                                    const&amp;, Attributes const&amp;, Configure
                                    const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an interrupt state with entry, exit behaviors, attributes,
                            configuration (deferred events, flags) and a base state:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class
                                    EndInterruptEvent,class Expr1, class Expr2, class Attributes,
                                    class Configure, class Base> func_state&lt;...>
                                    build_interrupt_state</funcdef>
                                <paramdef>EndInterruptEvent const&amp;,Expr1 const&amp;, Expr2
                                    const&amp;, Attributes const&amp;, Configure const&amp;,
                                    Base</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Notice that this function requires the extra parameter class
                            StateNameTag to disambiguate states having the same parameters but still
                            being different.</para>
                    </refsect3>
                    <refsect3>
                        <title>build_entry_state</title>
                        <para>This function has several overloads. The return type is not relevant
                            to you as only decltype (return type) is what one needs.</para>
                        <para>Defines an entry pseudo state without entry or exit:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,int RegionIndex>
                                    entry_func_state&lt;...> build_entry_state</funcdef>
                                <paramdef/>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an entry pseudo state with entry behavior:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,int RegionIndex,class
                                    Expr1> entry_func_state&lt;...> build_entry_state</funcdef>
                                <paramdef>Expr1 const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an entry pseudo state with entry and exit behaviors:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,int RegionIndex,class
                                    Expr1, class Expr2> entry_func_state&lt;...>
                                    build_entry_state</funcdef>
                                <paramdef>Expr1 const&amp;,Expr2 const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an entry pseudo state with entry, exit behaviors and
                            attributes:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,int RegionIndex,class
                                    Expr1, class Expr2, class Attributes> entry_func_state&lt;...>
                                    build_entry_state</funcdef>
                                <paramdef>Expr1 const&amp;, Expr2 const&amp;, Attributes
                                    const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an entry pseudo state with entry, exit behaviors, attributes
                            and configuration (deferred events, flags):</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,int RegionIndex,class
                                    Expr1, class Expr2, class Attributes, class Configure>
                                    entry_func_state&lt;...> build_entry_state</funcdef>
                                <paramdef>Expr1 const&amp;, Expr2 const&amp;, Attributes const&amp;,
                                    Configure const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an entry pseudo state with entry, exit behaviors, attributes,
                            configuration (deferred events, flags) and a base state:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,int RegionIndex,class
                                    Expr1, class Expr2, class Attributes, class Configure, class
                                    Base> entry_func_state&lt;...> build_entry_state</funcdef>
                                <paramdef>Expr1 const&amp;, Expr2 const&amp;, Attributes const&amp;,
                                    Configure const&amp;, Base</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Notice that this function requires the extra parameter class
                            StateNameTag to disambiguate states having the same parameters but still
                            being different.</para>
                    </refsect3>
                    <refsect3>
                        <title>build_exit_state</title>
                        <para>This function has several overloads. The return type is not relevant
                            to you as only decltype (return type) is what one needs.</para>
                        <para>Defines an exit pseudo state without entry or exit:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Event>
                                    exit_func_state&lt;...> build_exit_state</funcdef>
                                <paramdef>Event const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an exit pseudo state with entry behavior:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Event,class Expr1>
                                    exit_func_state&lt;...> build_exit_state</funcdef>
                                <paramdef>Event const&amp;,Expr1 const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an exit pseudo state with entry and exit behaviors:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Event,class Expr1,
                                    class Expr2> exit_func_state&lt;...> build_exit_state</funcdef>
                                <paramdef>Event const&amp;,Expr1 const&amp;,Expr2
                                    const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an exit pseudo state with entry, exit behaviors and
                            attributes:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Event,class Expr1,
                                    class Expr2, class Attributes> exit_func_state&lt;...>
                                    build_exit_state</funcdef>
                                <paramdef>Event const&amp;,Expr1 const&amp;, Expr2 const&amp;,
                                    Attributes const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an exit pseudo state with entry, exit behaviors, attributes
                            and configuration (deferred events, flags):</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Event,class Expr1,
                                    class Expr2, class Attributes, class Configure>
                                    exit_func_state&lt;...> build_exit_state</funcdef>
                                <paramdef>Event const&amp;,Expr1 const&amp;, Expr2 const&amp;,
                                    Attributes const&amp;, Configure const&amp;</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Defines an exit pseudo state with entry, exit behaviors, attributes,
                            configuration (deferred events, flags) and a base state:</para>
                        <funcsynopsis>
                            <funcprototype>
                                <funcdef>template &lt;class StateNameTag,class Event,class Expr1,
                                    class Expr2, class Attributes, class Configure, class Base>
                                    exit_func_state&lt;...> build_exit_state</funcdef>
                                <paramdef>Event const&amp;,Expr1 const&amp;, Expr2 const&amp;,
                                    Attributes const&amp;, Configure const&amp;, Base</paramdef>
                            </funcprototype>
                        </funcsynopsis>
                        <para>Notice that this function requires the extra parameter class
                            StateNameTag to disambiguate states having the same parameters but still
                            being different.</para>
                    </refsect3>
                    <refsect3>
                        <title>build_explicit_entry_state</title>
                        <para>This function has the same overloads as build_entry_state and
                            explicit_entry_func_state as return type.</para>
                    </refsect3>
                </refsect2>
            </refsect1>
            <refsect1>
                <title>msm/front/euml/common.hpp</title>
                <refsect2>
                    <title>types</title>
                    <refsect3>
                        <title>euml_event</title>
                        <para>The basic type for events with eUML.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template &lt;class EventName> euml_event;</classname>
                            </ooclass>
                        </classsynopsis>
                        <programlisting>struct play : euml_event&lt;play>{};</programlisting>
                    </refsect3>
                    <refsect3>
                        <title>euml_state</title>
                        <para>The basic type for states with eUML. You will usually not use this
                            type directly as it is easier to use BOOST_MSM_EUML_STATE,
                            BOOST_MSM_EUML_INTERRUPT_STATE, BOOST_MSM_EUML_TERMINATE_STATE,
                            BOOST_MSM_EUML_EXPLICIT_ENTRY_STATE, BOOST_MSM_EUML_ENTRY_STATE or
                            BOOST_MSM_EUML_EXIT_STATE.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template &lt;class StateName> euml_state;</classname>
                            </ooclass>
                        </classsynopsis>
                        <para>You can however use this type directly if you want to provide your
                            state with extra functions or provide entry or exit behaviors without
                            functors, for example:</para>
                        <programlisting>struct Empty : public msm::front::state&lt;> , public euml_state&lt;Empty> 
{
    void foo() {...}
    template &lt;class Event,class Fsm>
    void on_entry(Event const&amp; evt,Fsm&amp; fsm){...}
};</programlisting>
                    </refsect3>
                    <refsect3>
                        <title>euml_flag</title>
                        <para>The basic type for flags with eUML.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template &lt;class FlagName> euml_flag;</classname>
                            </ooclass>
                        </classsynopsis>
                        <programlisting>struct PlayingPaused: euml_flag&lt;PlayingPaused>{};</programlisting>
                    </refsect3>
                    <refsect3>
                        <title>euml_action</title>
                        <para>The basic type for state or transition behaviors and guards with
                            eUML.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template &lt;class AcionName> euml_action;</classname>
                            </ooclass>
                        </classsynopsis>
                        <programlisting>struct close_drawer : euml_action&lt;close_drawer>
{
    template &lt;class Fsm,class Evt,class SourceState,class TargetState>
    void operator()(Evt const&amp; , Fsm&amp;, SourceState&amp; ,TargetState&amp; ) {...}
};</programlisting>
                        <para>Or, as state entry or exit behavior:</para>
                        <programlisting>struct Playing_Entry : euml_action&lt;Playing_Entry>
{
    template &lt;class Event,class Fsm,class State>
    void operator()(Event const&amp;,Fsm&amp; fsm,State&amp; ){...}
};</programlisting>
                    </refsect3>
                    <refsect3>
                        <title>euml_config</title>
                        <para>The basic type for configuration possibilities with eUML.</para>
                        <classsynopsis>
                            <ooclass>
                                <classname>template &lt;class ConfigName> euml_config;</classname>
                            </ooclass>
                        </classsynopsis>
                        <para>You normally do not use this type directly but instead the instances
                            of predefined configuration:<itemizedlist>
                                <listitem>
                                    <para>no_exception: disable catching exceptions</para>
                                </listitem>
                                <listitem>
                                    <para>no_msg_queue: disable message queue. The message queue
                                        allows you to send an event for procesing while in an event
                                        processing.</para>
                                </listitem>
                                <listitem>
                                    <para>deferred_events: manually enable handling of deferred
                                        events</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>invalid_type</title>
                        <para>Type returned by grammar parsers if the grammar is invalid. Seeing
                            this type will result in a static assertion.</para>
                    </refsect3>
                    <refsect3>
                        <title>no_action</title>
                        <para>Placeholder type for use in entry/exit or transition behaviors, which
                            does absolutely nothing.</para>
                    </refsect3>
                    <refsect3>
                        <title>source_</title>
                        <para>Generic object or function for the source state of a given transition:<itemizedlist>
                                <listitem>
                                    <para>as object: returns by reference the source state of a
                                        transition, usually to be used by another function (usually
                                        one created by MSM_EUML_METHOD or MSM_EUML_FUNCTION).</para>
                                    <para>Example:
                                        <programlisting>some_user_function_(source_)</programlisting></para>
                                </listitem>
                                <listitem>
                                    <para>as function: returns by reference the attribute passed as
                                        parameter.</para>
                                    <para>Example:
                                        <programlisting>source_(m_counter)++</programlisting></para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>target_</title>
                        <para>Generic object or function for the target state of a given transition:<itemizedlist>
                                <listitem>
                                    <para>as object: returns by reference the target state of a
                                        transition, usually to be used by another function (usually
                                        one created by MSM_EUML_METHOD or MSM_EUML_FUNCTION).</para>
                                    <para>Example:
                                        <programlisting>some_user_function_(target_)</programlisting></para>
                                </listitem>
                                <listitem>
                                    <para>as function: returns by reference the attribute passed as
                                        parameter.</para>
                                    <para>Example:
                                        <programlisting>target_(m_counter)++</programlisting></para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>state_</title>
                        <para>Generic object or function for the state of a given entry / exit
                            behavior. state_ means source_ while in the context of an exit behavior
                            and target_ in the context of an entry behavior:<itemizedlist>
                                <listitem>
                                    <para>as object: returns by reference the current state, usually
                                        to be used by another function (usually one created by
                                        MSM_EUML_METHOD or MSM_EUML_FUNCTION).</para>
                                    <para>Example:
                                        <programlisting>some_user_function_(state_) // calls some_user_function on the current state</programlisting></para>
                                </listitem>
                                <listitem>
                                    <para>as function: returns by reference the attribute passed as
                                        parameter.</para>
                                    <para>Example:
                                        <programlisting>state_(m_counter)++</programlisting></para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>event_</title>
                        <para>Generic object or function for the event triggering a given transition
                            (valid in a transition behavior, as well as in state entry/exit behaviors):<itemizedlist>
                                <listitem>
                                    <para>as object: returns by reference the event of a transition,
                                        usually to be used by another function (usually one created
                                        by MSM_EUML_METHOD or MSM_EUML_FUNCTION).</para>
                                    <para>Example:
                                        <programlisting>some_user_function_(event_)</programlisting></para>
                                </listitem>
                                <listitem>
                                    <para>as function: returns by reference the attribute passed as
                                        parameter.</para>
                                    <para>Example:
                                        <programlisting>event_(m_counter)++</programlisting></para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>fsm_</title>
                        <para>Generic object or function for the state machine containing a given transition:<itemizedlist>
                                <listitem>
                                    <para>as object: returns by reference the event of a transition,
                                        usually to be used by another function (usually one created
                                        by MSM_EUML_METHOD or MSM_EUML_FUNCTION).</para>
                                    <para>Example:
                                        <programlisting>some_user_function_(fsm_)</programlisting></para>
                                </listitem>
                                <listitem>
                                    <para>as function: returns by reference the attribute passed as
                                        parameter.</para>
                                    <para>Example:
                                        <programlisting>fsm_(m_counter)++</programlisting></para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>substate_</title>
                        <para>Generic object or function returning a state of a given state machine:<itemizedlist>
                                <listitem>
                                    <para>with 1 parameter: returns by reference the state passed as
                                        parameter, usually to be used by another function (usually
                                        one created by MSM_EUML_METHOD or MSM_EUML_FUNCTION).</para>
                                    <para>Example:
                                        <programlisting>some_user_function_(substate_(my_state))</programlisting></para>
                                </listitem>
                                <listitem>
                                    <para>with 2 parameters: returns by reference the state passed
                                        as first parameter from the state machine passed as second
                                        parameter, usually to be used by another function (usually
                                        one created by MSM_EUML_METHOD or MSM_EUML_FUNCTION). This
                                        makes sense when used in combination with attribute_.</para>
                                    <para>Example (equivalent to the previous example):
                                        <programlisting>some_user_function_(substate_(my_state,fsm_))</programlisting></para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>attribute_</title>
                        <para>Generic object or function returning the attribute passed (by name) as
                            second parameter of the thing passed as first (a state, event or state
                            machine). Example: </para>
                        <para>
                            <programlisting>attribute_(substate_(my_state),cd_name_attribute)++</programlisting>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>True_</title>
                        <para>Functor returning true for transition or state behaviors. Like all
                            constants, only the functor form exists, so parenthesis are necessary.
                            Example:</para>
                        <para>
                            <programlisting>if_then_(True_(),/* some action always called*/)</programlisting>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>False_</title>
                        <para>Functor returning false for transition or state behaviors. Like all
                            constants, only the functor form exists, so parenthesis are necessary.
                            Example:</para>
                        <para>
                            <programlisting>if_then_(False_(),/* some action never called */)</programlisting>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>Int_&lt;int value></title>
                        <para>Functor returning an integer value for transition or state behaviors.
                            Like all constants, only the functor form exists, so parenthesis are
                            necessary. Example:</para>
                        <para>
                            <programlisting>target_(m_ringing_cpt) = Int_&lt;RINGING_TIME>() // RINGING_TIME is a constant</programlisting>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>Char_&lt;char value></title>
                        <para>Functor returning a char value for transition or state behaviors. Like
                            all constants, only the functor form exists, so parenthesis are
                            necessary. Example:</para>
                        <para>
                            <programlisting>// look for 'S' in event.m_song
[string_find_(event_(m_song),Char_&lt;'S'>(),Size_t_&lt;0>()) != Npos_&lt;string>()]</programlisting>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>Size_t_&lt;size_t value></title>
                        <para>Functor returning a size_t value for transition or state behaviors.
                            Like all constants, only the functor form exists, so parenthesis are
                            necessary. Example:</para>
                        <para>
                            <programlisting>substr_(event_(m_song),Size_t_&lt;1>()) // returns a substring of event.m_song</programlisting>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>String_ &lt; mpl::string ></title>
                        <para>Functor returning a string for transition or state behaviors. Like all
                            constants, only the functor form exists, so parenthesis are necessary.
                            Requires boost >= 1.40 for mpl::string.</para>
                        <para>Example:</para>
                        <para>
                            <programlisting>// adds "Let it be" to fsm.m_src_container
push_back_(fsm_(m_src_container), String_&lt;mpl::string&lt;'Let','it ','be'> >())</programlisting>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>Predicate_ &lt; some_stl_compatible_functor ></title>
                        <para>This functor eUML-enables a STL functor (for use in an algorithm).
                            This is necessary because all what is in the transition table must be a
                            eUML terminal.</para>
                        <para>Example:</para>
                        <programlisting>//equivalent to: 
//std::accumulate(fsm.m_vec.begin(),fsm.m_vec.end(),1,std::plus&lt;int>())== 1
accumulate_(begin_(fsm_(m_vec)),end_(fsm_(m_vec)),Int_&lt;1>(),
            Predicate_&lt;std::plus&lt;int> >()) == Int_&lt;1>())</programlisting>
                    </refsect3>
                    <refsect3>
                        <title>process_</title>
                        <para>This function sends an event to up to 4 state machines by calling
                                <code>process_event</code> on them:<itemizedlist>
                                <listitem>
                                    <para><code>process_(some_event)</code> : processes an event in
                                        the current (containing) state machine.</para>
                                </listitem>
                                <listitem>
                                    <para><code>process_(some_event [,fsm1...fsm4] )</code> :
                                        processes the same event in the 1-4 state machines passed as
                                        argument.</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>process2_</title>
                        <para>This function sends an event to up to 3 state machines by calling
                                <code>process_event</code> on them and copy-constructing the event
                            from the data passed as second parameter:<itemizedlist>
                                <listitem>
                                    <para><code>process2_(some_event, some_data)</code> : processes
                                        an event in the current (containing) state machine.</para>
                                </listitem>
                                <listitem>
                                    <para><code>process2_(some_event, some_data [,fsm1...fsm3]
                                            )</code> : processes the same event in the 1-3 state
                                        machines passed as argument.</para>
                                </listitem>
                            </itemizedlist></para>
                        <para>Example: </para>
                        <para>
                            <programlisting>// processes NotFound on current state machine, 
// copy-constructed with event.m_song
process2_(NotFound,event_(m_song))</programlisting>
                        </para>
                        <para>With the following definitions:</para>
                        <programlisting>BOOST_MSM_EUML_DECLARE_ATTRIBUTE(std::string,m_song)//declaration of m_song
NotFound (const string&amp; data) // copy-constructor of NotFound</programlisting>
                    </refsect3>
                    <refsect3>
                        <title>is_flag_</title>
                        <para>This function tells if a flag is active by calling
                                <code>is_flag_active</code> on the current state machine or one
                            passed as parameter:<itemizedlist>
                                <listitem>
                                    <para><code>is_flag_(some_flag)</code> : calls
                                            <code>is_flag_active</code> on the current (containing)
                                        state machine.</para>
                                </listitem>
                                <listitem>
                                    <para><code>is_flag_(some_flag, some_fsm)</code> :calls
                                            <code>is_flag_active</code> on the state machine.passed
                                        as argument.</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>defer_</title>
                        <para>This object defers the current event by calling
                                <code>defer_event</code> on the current state machine.
                            Example:</para>
                        <programlisting>Empty() + play() / defer_</programlisting>
                    </refsect3>
                    <refsect3>
                        <title>explicit_(submachine-name,state-name)</title>
                        <para>Used as transition's target, causes an explicit entry into the given
                            state from the given submachine. Several explicit_ as targets, separated
                            by commas, means a fork. The state must have been declared as such using
                            BOOST_MSM_EUML_EXPLICIT_ENTRY_STATE.</para>
                    </refsect3>
                    <refsect3>
                        <title>entry_pt_(submachine-name,state-name)</title>
                        <para>Used as transition's target from a containing state machine, causes
                            submachine-name to be entered using the given entry pseudo-state. This
                            state must have been declared as pseudo entry using
                            BOOST_MSM_EUML_ENTRY_STATE.</para>
                    </refsect3>
                    <refsect3>
                        <title>exit_pt_(submachine-name,state-name)</title>
                        <para>Used as transition's source from a containing state machine, causes
                            submachine-name to be left using the given exit pseudo-state. This state
                            must have been declared as pseudo exit using
                            BOOST_MSM_EUML_EXIT_STATE.</para>
                    </refsect3>
                    <refsect3>
                        <title>MSM_EUML_FUNCTION</title>
                        <para>This macro creates a eUML function and a functor for use with the
                            functor front-end, based on a free function:<itemizedlist>
                                <listitem>
                                    <para>first parameter: the name of the functor</para>
                                </listitem>
                                <listitem>
                                    <para>second parameter: the underlying function</para>
                                </listitem>
                                <listitem>
                                    <para>third parameter: the eUML function name</para>
                                </listitem>
                                <listitem>
                                    <para>fourth parameter: the return type if used in a transition
                                        behavior</para>
                                </listitem>
                                <listitem>
                                    <para>fifth parameter: the return type if used in a state
                                        behavior (entry/exit)</para>
                                </listitem>
                            </itemizedlist> Note that the function itself can take up to 5
                            arguments.</para>
                        <para>Example:</para>
                        <para>
                            <programlisting>MSM_EUML_FUNCTION(BinarySearch_,std::binary_search,binary_search_,bool,bool)</programlisting>
                        </para>
                        <para>Can be used like:</para>
                        <para>
                            <programlisting>binary_search_(begin_(fsm_(m_var)),end_(fsm_(m_var)),Int_&lt;9>())</programlisting>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>MSM_EUML_METHOD</title>
                        <para>This macro creates a eUML function and a functor for use with the
                            functor front-end, based on a method:<itemizedlist>
                                <listitem>
                                    <para>first parameter: the name of the functor</para>
                                </listitem>
                                <listitem>
                                    <para>second parameter: the underlying function</para>
                                </listitem>
                                <listitem>
                                    <para>third parameter: the eUML function name</para>
                                </listitem>
                                <listitem>
                                    <para>fourth parameter: the return type if used in a transition
                                        behavior</para>
                                </listitem>
                                <listitem>
                                    <para>fifth parameter: the return type if used in a state
                                        behavior (entry/exit)</para>
                                </listitem>
                            </itemizedlist> Note that the method itself can take up to 4 arguments
                            (5 like for a free function - 1 for the object on which the method is
                            called).</para>
                        <para>Example:</para>
                        <programlisting>struct Empty : public msm::front::state&lt;> , public euml_state&lt;Empty> 
{
     void activate_empty() {std::cout &lt;&lt; "switching to Empty " &lt;&lt; std::endl;}
... 
};
MSM_EUML_METHOD(ActivateEmpty_,activate_empty,activate_empty_,void,void)</programlisting>
                        <para>Can be used like:</para>
                        <para>
                            <programlisting>Empty == Open + open_close / (close_drawer , activate_empty_(target_))</programlisting>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_ACTION(action-instance-name)</title>
                        <para>This macro declares a behavior type and a const instance for use in
                            state or transition behaviors. The action implementation itself follows
                            the macro declaration, for example:</para>
                        <programlisting>BOOST_MSM_EUML_ACTION(good_disk_format)
{
     template &lt;class Fsm,class Evt,class SourceState,class TargetState>
     void/bool operator()(Evt const&amp; evt,Fsm&amp;,SourceState&amp; ,TargetState&amp; ){...}
};</programlisting>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_FLAG(flag-instance-name)</title>
                        <para>This macro declares a flag type and a const instance for use in
                            behaviors.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_FLAG_NAME(flag-instance-name)</title>
                        <para>This macro returns the name of the flag type generated by
                            BOOST_MSM_EUML_FLAG. You need this where the type is required (usually
                            with the back-end method is_flag_active). For example:</para>
                        <programlisting>fsm.is_flag_active&lt;BOOST_MSM_EUML_FLAG_NAME(CDLoaded)>()</programlisting>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_DECLARE_ATTRIBUTE(event-type,event-name)</title>
                        <para>This macro declares an attribute called event-name of type event-type.
                            This attribute can then be made part of an attribute list using
                            BOOST_MSM_EUML_ATTRIBUTES.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_ATTRIBUTES(attributes-expression,attributes-name)</title>
                        <para>This macro declares an attribute list called attributes-name based on
                            the expression as first argument. These attributes can then be made part
                            of an event using BOOST_MSM_EUML_EVENT_WITH_ATTRIBUTES, of a state as
                            3rd parameter of BOOST_MSM_EUML_STATE or of a state machine as 5th
                            parameter of BOOST_MSM_EUML_DECLARE_STATE_MACHINE.</para>
                        <para>Attributes are added using left-shift, for example:</para>
                        <programlisting>// m_song is of type std::string
BOOST_MSM_EUML_DECLARE_ATTRIBUTE(std::string,m_song)
// contains one attribute, m_song
BOOST_MSM_EUML_ATTRIBUTES((attributes_ &lt;&lt; m_song ), FoundDef)</programlisting>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_EVENT(event-instance name)</title>
                        <para>This macro defines an event type (event-instance-name_helper) and
                            declares a const instance of this event type called event-instance-name
                            for use in a transition table or state behaviors.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_EVENT_WITH_ATTRIBUTES(event-instance-name,attributes)</title>
                        <para>This macro defines an event type (event-instance-name_helper) and
                            declares a const instance of this event type called event-instance-name
                            for use in a transition table or state behaviors. The event will have as
                            attributes the ones passed by the second argument:</para>
                        <para><code>BOOST_MSM_EUML_EVENT_WITH_ATTRIBUTES(Found,FoundDef)</code>
                        </para>
                        <para>The created event instance supports operator()(attributes) so that
                            <programlisting>my_back_end.process_event(Found(some_string))</programlisting>
                            is possible.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_EVENT_NAME(event-instance-name)</title>
                        <para>This macro returns the name of the event type generated by
                            BOOST_MSM_EUML_EVENT or BOOST_MSM_EUML_EVENT_WITH_ATTRIBUTES. You need
                            this where the type is required (usually inside a back-end definition).
                            For example:</para>
                        <para>
                            <programlisting>typedef msm::back::state_machine&lt;Playing_,
msm::back::ShallowHistory&lt;mpl::vector&lt;BOOST_MSM_EUML_EVENT_NAME(end_pause)
> > > Playing_type;</programlisting>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_STATE(build-expression,state-instance-name)</title>
                        <para>This macro defines a state type (state-instance-name_helper) and
                            declares a const instance of this state type called state-instance-name
                            for use in a transition table or state behaviors.</para>
                        <para>There are several possibilitites for the expression syntax:<itemizedlist>
                                <listitem>
                                    <para>(): state without entry or exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1): state with entry but no exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2): state with entry and exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes): state with entry and exit
                                        action, defining some attributes.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes,Configure): state with entry and
                                        exit action, defining some attributes and flags (standard
                                        MSM flags) or deferred events (standard MSM deferred
                                        events).</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes,Configure,Base): state with entry
                                        and exit action, defining some attributes, flags and
                                        deferred events (plain msm deferred events) and a
                                        non-default base state (as defined in standard MSM).</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_INTERRUPT_STATE(build-expression,state-instance-name)</title>
                        <para>This macro defines an interrupt state type
                            (state-instance-name_helper) and declares a const instance of this state
                            type called state-instance-name for use in a transition table or state
                            behaviors.</para>
                        <para>There are several possibilitites for the expression syntax. In all of
                            them, the first argument is the name of the event (generated by one of
                            the previous macros) ending the interrupt:<itemizedlist>
                                <listitem>
                                    <para>(end_interrupt_event): interrupt state without entry or
                                        exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(end_interrupt_event,Expr1): interrupt state with entry
                                        but no exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(end_interrupt_event,Expr1,Expr2): interrupt state with
                                        entry and exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(end_interrupt_event,Expr1,Expr2,Attributes): interrupt
                                        state with entry and exit action, defining some
                                        attributes.</para>
                                </listitem>
                                <listitem>
                                    <para>(end_interrupt_event,Expr1,Expr2,Attributes,Configure):
                                        interrupt state with entry and exit action, defining some
                                        attributes and flags (standard MSM flags) or deferred events
                                        (standard MSM deferred events).</para>
                                </listitem>
                                <listitem>
                                    <para>(end_interrupt_event,Expr1,Expr2,Attributes,Configure,Base):
                                        interrupt state with entry and exit action, defining some
                                        attributes, flags and deferred events (plain msm deferred
                                        events) and a non-default base state (as defined in standard
                                        MSM).</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_TERMINATE_STATE(build-expression,state-instance-name)</title>
                        <para>This macro defines a terminate pseudo-state type
                            (state-instance-name_helper) and declares a const instance of this state
                            type called state-instance-name for use in a transition table or state
                            behaviors.</para>
                        <para>There are several possibilitites for the expression syntax:<itemizedlist>
                                <listitem>
                                    <para>(): terminate pseudo-state without entry or exit
                                        action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1): terminate pseudo-state with entry but no exit
                                        action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2): terminate pseudo-state with entry and exit
                                        action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes): terminate pseudo-state with
                                        entry and exit action, defining some attributes.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes,Configure): terminate pseudo-state
                                        with entry and exit action, defining some attributes and
                                        flags (standard MSM flags) or deferred events (standard MSM
                                        deferred events).</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes,Configure,Base): terminate
                                        pseudo-state with entry and exit action, defining some
                                        attributes, flags and deferred events (plain msm deferred
                                        events) and a non-default base state (as defined in standard
                                        MSM).</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_EXIT_STATE(build-expression,state-instance-name)</title>
                        <para>This macro defines an exit pseudo-state type
                            (state-instance-name_helper) and declares a const instance of this state
                            type called state-instance-name for use in a transition table or state
                            behaviors.</para>
                        <para>There are several possibilitites for the expression syntax:<itemizedlist>
                                <listitem>
                                    <para>(forwarded_event):exit pseudo-state without entry or exit
                                        action.</para>
                                </listitem>
                                <listitem>
                                    <para>(forwarded_event,Expr1): exit pseudo-state with entry but
                                        no exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(forwarded_event,Expr1,Expr2): exit pseudo-state with
                                        entry and exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(forwarded_event,Expr1,Expr2,Attributes): exit
                                        pseudo-state with entry and exit action, defining some
                                        attributes.</para>
                                </listitem>
                                <listitem>
                                    <para>(forwarded_event,Expr1,Expr2,Attributes,Configure): exit
                                        pseudo-state with entry and exit action, defining some
                                        attributes and flags (standard MSM flags) or deferred events
                                        (standard MSM deferred events).</para>
                                </listitem>
                                <listitem>
                                    <para>(forwarded_event,Expr1,Expr2,Attributes,Configure,Base):
                                        exit pseudo-state with entry and exit action, defining some
                                        attributes, flags and deferred events (plain msm deferred
                                        events) and a non-default base state (as defined in standard
                                        MSM).</para>
                                </listitem>
                            </itemizedlist></para>
                        <para>Note that the forwarded_event must be constructible from the event
                            sent by the submachine containing the exit point.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_ENTRY_STATE(int
                            region-index,build-expression,state-instance-name)</title>
                        <para>This macro defines an entry pseudo-state type
                            (state-instance-name_helper) and declares a const instance of this state
                            type called state-instance-name for use in a transition table or state
                            behaviors.</para>
                        <para>There are several possibilitites for the expression syntax:<itemizedlist>
                                <listitem>
                                    <para>(): entry pseudo-state without entry or exit
                                        action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1): entry pseudo-state with entry but no exit
                                        action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2): entry pseudo-state with entry and exit
                                        action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes): entry pseudo-state with entry
                                        and exit action, defining some attributes.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes,Configure): entry pseudo-state
                                        with entry and exit action, defining some attributes and
                                        flags (standard MSM flags) or deferred events (standard MSM
                                        deferred events).</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes,Configure,Base): entry
                                        pseudo-state with entry and exit action, defining some
                                        attributes, flags and deferred events (plain msm deferred
                                        events) and a non-default base state (as defined in standard
                                        MSM).</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_EXPLICIT_ENTRY_STATE(int
                            region-index,build-expression,state-instance-name)</title>
                        <para>This macro defines a submachine's substate type
                            (state-instance-name_helper), which can be explicitly entered and also
                            declares a const instance of this state type called state-instance-name
                            for use in a transition table or state behaviors.</para>
                        <para>There are several possibilitites for the expression syntax:<itemizedlist>
                                <listitem>
                                    <para>(): state without entry or exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1): state with entry but no exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2): state with entry and exit action.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes): state with entry and exit
                                        action, defining some attributes.</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes,Configure): state with entry and
                                        exit action, defining some attributes and flags (standard
                                        MSM flags) or deferred events (standard MSM deferred
                                        events).</para>
                                </listitem>
                                <listitem>
                                    <para>(Expr1,Expr2,Attributes,Configure,Base): state with entry
                                        and exit action, defining some attributes, flags and
                                        deferred events (plain msm deferred events) and a
                                        non-default base state (as defined in standard MSM).</para>
                                </listitem>
                            </itemizedlist></para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_STATE_NAME(state-instance-name)</title>
                        <para>This macro returns the name of the state type generated by
                            BOOST_MSM_EUML_STATE or other state macros. You need this where the type
                            is required (usually using a backend function). For example:</para>
                        <para>
                            <programlisting>fsm.get_state&lt;BOOST_MSM_EUML_STATE_NAME(StringFind)&amp;>().some_state_function();</programlisting>
                        </para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_DECLARE_STATE(build-expression,state-instance-name)</title>
                        <para>Like BOOST_MSM_EUML_STATE but does not provide an instance, simply a
                            type declaration.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_DECLARE_INTERRUPT_STATE(build-expression,state-instance-name)</title>
                        <para>Like BOOST_MSM_EUML_INTERRUPT_STATE but does not provide an instance,
                            simply a type declaration.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_DECLARE_TERMINATE_STATE(build-expression,state-instance-name)</title>
                        <para>Like BOOST_MSM_EUML_TERMINATE_STATE but does not provide an instance,
                            simply a type declaration.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_DECLARE_EXIT_STATE(build-expression,state-instance-name)</title>
                        <para>Like BOOST_MSM_EUML_EXIT_STATE but does not provide an instance,
                            simply a type declaration.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_DECLARE_ENTRY_STATE(int
                            region-index,build-expression,state-instance-name)</title>
                        <para>Like BOOST_MSM_EUML_ENTRY_STATE but does not provide an instance,
                            simply a type declaration.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_DECLARE_EXPLICIT_ENTRY_STATE(int
                            region-index,build-expression,state-instance-name)</title>
                        <para>Like BOOST_MSM_EUML_EXPLICIT_ENTRY_STATE but does not provide an
                            instance, simply a type declaration.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_TRANSITION_TABLE(expression,
                            table-instance-name)</title>
                        <para>This macro declares a transition table type and also declares a const
                            instance of the table which can then be used in a state machine
                            declaration (see BOOST_MSM_EUML_DECLARE_STATE_MACHINE).The expression
                            must follow the <command xlink:href="#reference-stt-grammar">transition
                                table grammar</command>.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_DECLARE_TRANSITION_TABLE(iexpression,table-instance-name)</title>
                        <para>Like BOOST_MSM_EUML_TRANSITION_TABLE but does not provide an instance,
                            simply a type declaration.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_INTERNAL_TRANSITION_TABLE(expression,
                            table-instance-name)</title>
                        <para>This macro declares a transition table type and also declares a const
                            instance of the table.The expression must follow the <command
                                xlink:href="#reference-stt-grammar">transition table
                                grammar</command>. For the moment, this macro is not used.</para>
                    </refsect3>
                    <refsect3>
                        <title>BOOST_MSM_EUML_DECLARE_INTERNAL_TRANSITION_TABLE(iexpression,table-instance-name)</title>
                        <para>Like BOOST_MSM_EUML_TRANSITION_TABLE but does not provide an instance,
                            simply a type declaration. This is currently the only way to declare an
                            internal transition table with eUML. For example:</para>
                        <programlisting>BOOST_MSM_EUML_DECLARE_STATE((Open_Entry,Open_Exit),Open_def)
struct Open_impl : public Open_def
{
    BOOST_MSM_EUML_DECLARE_INTERNAL_TRANSITION_TABLE((
          open_close [internal_guard1] / internal_action1 ,
          open_close [internal_guard2] / internal_action2
    ))
};                    </programlisting>
                    </refsect3>
                </refsect2>
            </refsect1>
        </refentry>
    </part>
</book>
