// Boost.Bimap

//

// Copyright (c) 2006-2007 Matias Capeletto

//

// Distributed under the Boost Software License, Version 1.0.

// (See accompanying file LICENSE_1_0.txt or copy at

// http://www.boost.org/LICENSE_1_0.txt)



/// \file relation/support/data_extractor.hpp

/// \brief Data extraction functor.



#ifndef BOOST_BIMAP_RELATION_SUPPORT_DATA_EXTRACTOR_HPP

#define BOOST_BIMAP_RELATION_SUPPORT_DATA_EXTRACTOR_HPP



#if defined(_MSC_VER) && (_MSC_VER>=1200)

#pragma once

#endif



#include <boost/config.hpp>



#include <boost/bimap/relation/detail/metadata_access_builder.hpp>



/** \struct boost::bimaps::relation::support::data_extractor



\brief Data extraction functor.



\ingroup relation_group

                                                                    **/



#ifndef BOOST_BIMAP_DOXYGEN_WILL_NOT_PROCESS_THE_FOLLOWING_LINES



namespace boost {

namespace bimaps {

namespace relation {

namespace support {



template< class Tag, class Relation >

struct data_extractor_implementation;



template< class Relation >

struct data_extractor_implementation< member_at::left, Relation > :

    public std::unary_function<Relation,BOOST_DEDUCED_TYPENAME Relation::left_value_type>

{

    BOOST_DEDUCED_TYPENAME Relation::left_value_type const &

        operator()(Relation const & rel) const

    {

        return rel.left;

    }



    BOOST_DEDUCED_TYPENAME Relation::left_value_type &

        operator()(Relation       & rel) const

    {

        return rel.left;

    }

};



template< class Relation >

struct data_extractor_implementation< member_at::right, Relation > :

    public std::unary_function<Relation,BOOST_DEDUCED_TYPENAME Relation::right_value_type>

{

    BOOST_DEDUCED_TYPENAME Relation::right_value_type const & 

        operator()(Relation const & rel) const

    {

        return rel.right;

    }



    BOOST_DEDUCED_TYPENAME Relation::right_value_type & 

        operator()(Relation       & rel) const

    {

        return rel.right;

    }

};



template< class Tag, class Relation >

struct data_extractor

{

    typedef data_extractor_implementation

    <

        BOOST_DEDUCED_TYPENAME member_with_tag<Tag,Relation>::type,

        Relation



    > type;

};



template< class Relation >

struct both_keys_extractor

{

    typedef BOOST_DEDUCED_TYPENAME Relation::storage_base result_type;



     const result_type & operator()(const Relation & rel) const

    {

        return rel;

    }



    result_type & operator()( Relation & rel) const

    {

        return rel;

    }

};



} // namespace support

} // namespace relation

} // namespace bimaps

} // namespace boost



#endif // BOOST_BIMAP_DOXYGEN_WILL_NOT_PROCESS_THE_FOLLOWING_LINES



#endif // BOOST_BIMAP_RELATION_SUPPORT_DATA_EXTRACTOR_HPP



