relation/support/data_extractor.hpp

0001 // Boost.Bimap
0002 //
0003 // Copyright (c) 2006-2007 Matias Capeletto
0004 //
0005 // Distributed under the Boost Software License, Version 1.0.
0006 // (See accompanying file LICENSE_1_0.txt or copy at
0007 // http://www.boost.org/LICENSE_1_0.txt)
0008
0009 /// \file relation/support/data_extractor.hpp
0010 /// \brief Data extraction functor.
0011
0012 #ifndef BOOST_BIMAP_RELATION_SUPPORT_DATA_EXTRACTOR_HPP
0013 #define BOOST_BIMAP_RELATION_SUPPORT_DATA_EXTRACTOR_HPP
0014
0015 #if defined(_MSC_VER)
0016 #pragma once
0017 #endif
0018
0019 #include <boost/config.hpp>
0020
0021 #include <boost/bimap/relation/detail/metadata_access_builder.hpp>
0022
0023 /** \struct boost::bimaps::relation::support::data_extractor
0024
0025 \brief Data extraction functor.
0026
0027 \ingroup relation_group
0028                                                                     **/
0029
0030 #ifndef BOOST_BIMAP_DOXYGEN_WILL_NOT_PROCESS_THE_FOLLOWING_LINES
0031
0032 namespace boost {
0033 namespace bimaps {
0034 namespace relation {
0035 namespace support {
0036
0037 template< class Tag, class Relation >
0038 struct data_extractor_implementation;
0039
0040 template< class Relation >
0041 struct data_extractor_implementation< member_at::left, Relation >
0042 {
0043     typedef Relation argument_type;
0044     typedef BOOST_DEDUCED_TYPENAME Relation::left_value_type result_type;
0045
0046     BOOST_DEDUCED_TYPENAME Relation::left_value_type const &
0047         operator()(Relation const & rel) const
0048     {
0049         return rel.left;
0050     }
0051
0052     BOOST_DEDUCED_TYPENAME Relation::left_value_type &
0053         operator()(Relation       & rel) const
0054     {
0055         return rel.left;
0056     }
0057 };
0058
0059 template< class Relation >
0060 struct data_extractor_implementation< member_at::right, Relation >
0061 {
0062     typedef Relation argument_type;
0063     typedef BOOST_DEDUCED_TYPENAME Relation::right_value_type result_type;
0064
0065     BOOST_DEDUCED_TYPENAME Relation::right_value_type const &
0066         operator()(Relation const & rel) const
0067     {
0068         return rel.right;
0069     }
0070
0071     BOOST_DEDUCED_TYPENAME Relation::right_value_type &
0072         operator()(Relation       & rel) const
0073     {
0074         return rel.right;
0075     }
0076 };
0077
0078 template< class Tag, class Relation >
0079 struct data_extractor
0080 {
0081     typedef data_extractor_implementation
0082     <
0083         BOOST_DEDUCED_TYPENAME member_with_tag<Tag,Relation>::type,
0084         Relation
0085
0086     > type;
0087 };
0088
0089 template< class Relation >
0090 struct both_keys_extractor
0091 {
0092     typedef BOOST_DEDUCED_TYPENAME Relation::storage_base result_type;
0093
0094      const result_type & operator()(const Relation & rel) const
0095     {
0096         return rel;
0097     }
0098
0099     result_type & operator()( Relation & rel) const
0100     {
0101         return rel;
0102     }
0103 };
0104
0105 } // namespace support
0106 } // namespace relation
0107 } // namespace bimaps
0108 } // namespace boost
0109
0110 #endif // BOOST_BIMAP_DOXYGEN_WILL_NOT_PROCESS_THE_FOLLOWING_LINES
0111
0112 #endif // BOOST_BIMAP_RELATION_SUPPORT_DATA_EXTRACTOR_HPP
0113