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# inserter (class)

### Synopsis

    template<
          typename State
        , typename Operation
        >
    struct inserter
    {
        typedef State state;
        typedef Operation operation;
    };

### Description

A general-purpose model of the Inserter concept.

### Header

    #include <boost/mpl/inserter.hpp>

### Model of

Inserter

### Parameters

Parameter | Requirement | Description
--- | --- | ---
`State` | Any type | A initial state.
`Operation` | Binary Lambda Expression | An output operation.

### Expression semantics

The semantics of an expression are defined only where they differ from, or are not defined in Inserter.

For any binary Lambda Expression `op` and arbitrary type `state`:

Expression | Semantics
--- | ---
`inserter<op,state>` | An Inserter.

### Complexity

Amortized constant time.

### Example

    template< typename N > struct is_odd : bool_< ( N::value % 2 ) > {};

    typedef copy<
          range_c<int,0,10>
        , inserter< // a filtering 'push_back' inserter
              vector<>
            , if_< is_odd<_2>, push_back<_1,_2>, _1 >
            >
        >::type odds;

    BOOST_MPL_ASSERT(( equal< odds, vector_c<int,1,3,5,7,9>, equal_to<_,_> > ));

### See also

Algorithms, Inserter, Reversible Algorithm, front_inserter, back_inserter