| // 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/member_with_tag.hpp |
| /// \brief member_with_tag<tag,relation> metafunction |
| |
| #ifndef BOOST_BIMAP_RELATION_SUPPORT_MEMBER_WITH_TAG_HPP |
| #define BOOST_BIMAP_RELATION_SUPPORT_MEMBER_WITH_TAG_HPP |
| |
| #if defined(_MSC_VER) && (_MSC_VER>=1200) |
| #pragma once |
| #endif |
| |
| #include <boost/config.hpp> |
| |
| #include <boost/bimap/relation/member_at.hpp> |
| #include <boost/bimap/detail/debug/static_error.hpp> |
| #include <boost/utility/enable_if.hpp> |
| #include <boost/type_traits/is_same.hpp> |
| #include <boost/mpl/bool.hpp> |
| #include <boost/mpl/not.hpp> |
| #include <boost/mpl/and.hpp> |
| |
| /** \struct boost::bimaps::relation::support::member_with_tag |
| |
| \brief Metafunction to convert user tags to the member_at idiom. |
| |
| \code |
| |
| template< class Tag, class Relation > |
| struct member_with_tag |
| { |
| typedef member_at::{side} type; |
| }; |
| |
| \endcode |
| |
| We have to allow that all the metafunctions that works with tags |
| and retrieves data from a Relation will work with member_at idiom |
| even if the type was tagged. This will be great for the user, |
| because he can choose to tag a member after he is using the |
| relation and the code will still work. |
| |
| If we perform this check in every metafunction it will be very |
| tedious and error prone, so instead of that all metafunctions |
| that works with relations first call this metafunction that |
| convert the tag to a member_at tag. |
| |
| See also member_at, is_tag_of_member_at_left, is_tag_of_member_at_right. |
| \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, |
| class Enable = void |
| > |
| struct member_with_tag |
| { |
| BOOST_BIMAP_STATIC_ERROR( MEMBER_WITH_TAG_FAILURE, (Relation,Tag) ); |
| }; |
| |
| template< class Relation > |
| struct member_with_tag |
| < |
| member_at::left, Relation, void |
| > |
| { |
| typedef member_at::left type; |
| }; |
| |
| template< class Relation > |
| struct member_with_tag |
| < |
| member_at::right, Relation, void |
| > |
| { |
| typedef member_at::right type; |
| }; |
| |
| template< class Relation > |
| struct member_with_tag |
| < |
| member_at::info, Relation, void |
| > |
| { |
| typedef member_at::info type; |
| }; |
| |
| |
| template< class Tag, class Relation > |
| struct member_with_tag |
| < |
| Tag, Relation, |
| BOOST_DEDUCED_TYPENAME enable_if |
| < |
| mpl::and_ |
| < |
| mpl::not_< is_same<Tag,member_at::left> >, |
| is_same |
| < |
| Tag, |
| BOOST_DEDUCED_TYPENAME Relation::left_tag |
| > |
| > |
| |
| >::type |
| > |
| { |
| typedef member_at::left type; |
| }; |
| |
| template< class Tag, class Relation > |
| struct member_with_tag |
| < |
| Tag, |
| Relation, |
| BOOST_DEDUCED_TYPENAME enable_if |
| < |
| mpl::and_ |
| < |
| mpl::not_< is_same<Tag,member_at::right> >, |
| is_same |
| < |
| Tag, |
| BOOST_DEDUCED_TYPENAME Relation::right_tag |
| > |
| > |
| |
| >::type |
| > |
| { |
| typedef member_at::right type; |
| }; |
| |
| template< class Tag, class Relation > |
| struct member_with_tag |
| < |
| Tag, Relation, |
| BOOST_DEDUCED_TYPENAME enable_if |
| < |
| mpl::and_ |
| < |
| mpl::not_< is_same<Tag,member_at::info> >, |
| is_same |
| < |
| Tag, |
| BOOST_DEDUCED_TYPENAME Relation::info_tag |
| > |
| > |
| |
| >::type |
| > |
| { |
| typedef member_at::info type; |
| }; |
| |
| } // namespace support |
| } // namespace relation |
| } // namespace bimaps |
| } // namespace boost |
| |
| #endif // BOOST_BIMAP_DOXYGEN_WILL_NOT_PROCESS_THE_FOLLOWING_LINES |
| |
| #endif // BOOST_BIMAP_RELATION_SUPPORT_MEMBER_WITH_TAG_HPP |
| |
| |