Chris@16: /*=============================================================================
Chris@16:     Copyright (c) 2001-2011 Joel de Guzman
Chris@16: 
Chris@16:     Distributed under the Boost Software License, Version 1.0. (See accompanying 
Chris@16:     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: ==============================================================================*/
Chris@16: #if !defined(FUSION_HAS_KEY_09232005_1454)
Chris@16: #define FUSION_HAS_KEY_09232005_1454
Chris@16: 
Chris@101: #include <boost/fusion/support/config.hpp>
Chris@16: #include <boost/fusion/sequence/intrinsic_fwd.hpp>
Chris@16: #include <boost/fusion/support/tag_of.hpp>
Chris@16: #include <boost/fusion/iterator/equal_to.hpp>
Chris@16: #include <boost/fusion/algorithm/query/find.hpp>
Chris@16: #include <boost/fusion/sequence/intrinsic/end.hpp>
Chris@16: #include <boost/mpl/not.hpp>
Chris@16: 
Chris@16: namespace boost { namespace fusion
Chris@16: {
Chris@16:     struct void_;
Chris@16: 
Chris@16:     // Special tags:
Chris@16:     struct sequence_facade_tag;
Chris@16:     struct boost_array_tag; // boost::array tag
Chris@16:     struct mpl_sequence_tag; // mpl sequence tag
Chris@16:     struct std_pair_tag; // std::pair tag
Chris@16: 
Chris@16:     namespace extension
Chris@16:     {
Chris@16:         template <typename Tag>
Chris@16:         struct has_key_impl
Chris@16:         {
Chris@16:             template <typename Seq, typename Key>
Chris@16:             struct apply
Chris@16:               : mpl::not_<
Chris@16:                     typename result_of::equal_to<
Chris@16:                         typename result_of::find<Seq, Key>::type
Chris@16:                       , typename result_of::end<Seq>::type
Chris@16:                     >::type
Chris@16:                 >::type
Chris@16:             {};
Chris@16:         };
Chris@16: 
Chris@16:         template <>
Chris@16:         struct has_key_impl<sequence_facade_tag>
Chris@16:         {
Chris@16:             template <typename Sequence, typename Key>
Chris@16:             struct apply : Sequence::template has_key<Sequence, Key> {};
Chris@16:         };
Chris@16: 
Chris@16:         template <>
Chris@16:         struct has_key_impl<boost_array_tag>;
Chris@16: 
Chris@16:         template <>
Chris@16:         struct has_key_impl<mpl_sequence_tag>;
Chris@16: 
Chris@16:         template <>
Chris@16:         struct has_key_impl<std_pair_tag>;
Chris@16:     }
Chris@16:     
Chris@16:     namespace result_of
Chris@16:     {
Chris@16:         template <typename Sequence, typename Key>
Chris@16:         struct has_key 
Chris@16:             : extension::has_key_impl<typename detail::tag_of<Sequence>::type>::
Chris@16:                 template apply<Sequence, Key>
Chris@16:         {};
Chris@16:     }
Chris@16: 
Chris@16:     template <typename Key, typename Sequence>
Chris@101:     BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
Chris@16:     inline typename result_of::has_key<Sequence, Key>::type
Chris@16:     has_key(Sequence const&)
Chris@16:     {
Chris@16:         typedef typename result_of::has_key<Sequence, Key>::type result;
Chris@16:         return result();
Chris@16:     }
Chris@16: }}
Chris@16: 
Chris@16: #endif
Chris@16: