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## Struct template regex_compiler

boost::xpressive::regex_compiler — Class template regex_compiler is a factory for building basic_regex objects from a string.

## Synopsis

    // In header: <boost/xpressive/regex_compiler.hpp>

    template<typename BidiIter, typename RegexTraits, typename CompilerTraits>
    struct regex_compiler {
      // types
      typedef BidiIter                            iterator_type;
      typedef iterator_value< BidiIter >::type    char_type;
      typedef regex_constants::syntax_option_type flag_type;
      typedef RegexTraits                         traits_type;
      typedef traits_type::string_type            string_type;
      typedef traits_type::locale_type            locale_type;
      typedef traits_type::char_class_type        char_class_type;

      // construct/copy/destruct
      explicit regex_compiler(RegexTraits const & = RegexTraits());

      // public member functions
      locale_type imbue(locale_type);
      locale_type getloc() const;
      template<typename InputIter>
        basic_regex< BidiIter >
        compile(InputIter, InputIter, flag_type = regex_constants::ECMAScript);
      template<typename InputRange>
        disable_if< is_pointer< InputRange >, basic_regex< BidiIter > >::type
        compile(InputRange const &, flag_type = regex_constants::ECMAScript);
      basic_regex< BidiIter >
      compile(char_type const *, flag_type = regex_constants::ECMAScript);
      basic_regex< BidiIter > compile(char_type const *, std::size_t, flag_type);
      basic_regex< BidiIter > & operator[](string_type const &);
      basic_regex< BidiIter > const & operator[](string_type const &) const;

      // private member functions
      bool is_upper_(char_type) const;
    };

## Description

Class template regex_compiler is used to construct a basic_regex object from a string. The string should contain a valid regular expression. You can imbue a regex_compiler object with a locale, after which all basic_regex objects created with that regex_compiler object will use that locale. After creating a regex_compiler object, and optionally imbueing it with a locale, you can call the compile() method to construct a basic_regex object, passing it the string representing the regular expression. You can call compile() multiple times on the same regex_compiler object. Two basic_regex objects compiled from the same string will have different regex_id's.

### `regex_compiler` public construct/copy/destruct

1.     explicit regex_compiler(RegexTraits const & traits = RegexTraits());

### `regex_compiler` public member functions

1.     locale_type imbue(locale_type loc);

   Specify the locale to be used by a `regex_compiler`.

   Parameters:

   `loc` | The locale that this `regex_compiler` should use.

   Returns: | The previous locale.

2.     locale_type getloc() const;

   Get the locale used by a `regex_compiler`.

   Returns: | The locale used by this regex_compiler.

3.     template<typename InputIter>
         basic_regex< BidiIter >
         compile(InputIter begin, InputIter end,
                 flag_type flags = regex_constants::ECMAScript);

   Builds a `basic_regex` object from a range of characters.

   Parameters:

   `begin` | The beginning of a range of characters representing the regular expression to compile.
   `end` | The end of a range of characters representing the regular expression to compile.
   `flags` | Optional bitmask that determines how the pat string is interpreted. (See syntax_option_type.)

   Requires: | InputIter is a model of the InputIterator concept. [begin,end) is a valid range. The range of characters specified by [begin,end) contains a valid string-based representation of a regular expression.
   Returns: | A basic_regex object corresponding to the regular expression represented by the character range.
   Throws: | regex_error when the range of characters has invalid regular expression syntax.

4.     template<typename InputRange>
         disable_if< is_pointer< InputRange >, basic_regex< BidiIter > >::type
         compile(InputRange const & pat,
                 flag_type flags = regex_constants::ECMAScript);

   This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

5.     basic_regex< BidiIter >
       compile(char_type const * begin,
               flag_type flags = regex_constants::ECMAScript);

   This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

6.     basic_regex< BidiIter >
       compile(char_type const * begin, std::size_t size, flag_type flags);

   This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

7.     basic_regex< BidiIter > & operator[](string_type const & name);

   Return a reference to the named regular expression. If no such named regular expression exists, create a new regular expression and return a reference to it.

   Parameters:

   `name` | A std::string containing the name of the regular expression.

   Requires: | The string is not empty.
   Throws: | bad_alloc on allocation failure.

8.     basic_regex< BidiIter > const & operator[](string_type const & name) const;

   This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

### `regex_compiler` private member functions

1.     bool is_upper_(char_type ch) const;