Chris@16: /*=============================================================================
Chris@16:     Copyright (c) 2001-2011 Joel de Guzman
Chris@16:     Copyright (c) 2006 Dan Marsden
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(BOOST_FUSION_AT_KEY_20060304_1755)
Chris@16: #define BOOST_FUSION_AT_KEY_20060304_1755
Chris@16: 
Chris@101: #include <boost/fusion/support/config.hpp>
Chris@16: #include <boost/type_traits/is_const.hpp>
Chris@16: #include <boost/fusion/sequence/intrinsic_fwd.hpp>
Chris@16: #include <boost/fusion/algorithm/query/find.hpp>
Chris@16: #include <boost/fusion/iterator/deref_data.hpp>
Chris@16: #include <boost/fusion/support/tag_of.hpp>
Chris@16: #include <boost/fusion/support/detail/access.hpp>
Chris@16: 
Chris@16: namespace boost { namespace fusion
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 at_key_impl
Chris@16:         {
Chris@16:             template <typename Seq, typename Key>
Chris@16:             struct apply
Chris@16:             {
Chris@16:                 typedef typename
Chris@16:                     result_of::deref_data<
Chris@16:                         typename result_of::find<Seq, Key>::type
Chris@16:                     >::type
Chris@16:                 type;
Chris@16: 
Chris@101:                 BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
Chris@16:                 static type
Chris@16:                 call(Seq& seq)
Chris@16:                 {
Chris@16:                     return fusion::deref_data(fusion::find<Key>(seq));
Chris@16:                 }
Chris@16:             };
Chris@16:         };
Chris@16: 
Chris@16:         template <>
Chris@16:         struct at_key_impl<sequence_facade_tag>
Chris@16:         {
Chris@16:             template <typename Sequence, typename Key>
Chris@16:             struct apply : Sequence::template at_key_impl<Sequence, Key> {};
Chris@16:         };
Chris@16: 
Chris@16:         template <>
Chris@16:         struct at_key_impl<boost_array_tag>;
Chris@16: 
Chris@16:         template <>
Chris@16:         struct at_key_impl<mpl_sequence_tag>;
Chris@16: 
Chris@16:         template <>
Chris@16:         struct at_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 at_key
Chris@16:             : extension::at_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 
Chris@16:         lazy_disable_if<
Chris@16:             is_const<Sequence>
Chris@16:           , result_of::at_key<Sequence, Key>
Chris@16:         >::type
Chris@16:     at_key(Sequence& seq)
Chris@16:     {
Chris@16:         return result_of::at_key<Sequence, Key>::call(seq);
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::at_key<Sequence const, Key>::type
Chris@16:     at_key(Sequence const& seq)
Chris@16:     {
Chris@16:         return result_of::at_key<Sequence const, Key>::call(seq);
Chris@16:     }
Chris@16: }}
Chris@16: 
Chris@16: #endif