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_AT_05042005_0722)
Chris@16: #define FUSION_AT_05042005_0722
Chris@16: 
Chris@101: #include <boost/fusion/support/config.hpp>
Chris@16: #include <boost/mpl/int.hpp>
Chris@101: #include <boost/mpl/if.hpp>
Chris@101: #include <boost/mpl/less.hpp>
Chris@101: #include <boost/mpl/empty_base.hpp>
Chris@16: #include <boost/type_traits/is_const.hpp>
Chris@16: #include <boost/fusion/sequence/intrinsic_fwd.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_tuple_tag; // boost::tuples::tuple 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:     struct std_tuple_tag; // std::tuple tag
Chris@16: 
Chris@16:     namespace extension
Chris@16:     {
Chris@16:         template <typename Tag>
Chris@16:         struct at_impl
Chris@16:         {
Chris@16:             template <typename Sequence, typename N>
Chris@16:             struct apply;
Chris@16:         };
Chris@16: 
Chris@16:         template <>
Chris@16:         struct at_impl<sequence_facade_tag>
Chris@16:         {
Chris@16:             template <typename Sequence, typename N>
Chris@16:             struct apply : Sequence::template at<Sequence, N> {};
Chris@16:         };
Chris@16: 
Chris@16:         template <>
Chris@16:         struct at_impl<boost_tuple_tag>;
Chris@16: 
Chris@16:         template <>
Chris@16:         struct at_impl<boost_array_tag>;
Chris@16: 
Chris@16:         template <>
Chris@16:         struct at_impl<mpl_sequence_tag>;
Chris@16: 
Chris@16:         template <>
Chris@16:         struct at_impl<std_pair_tag>;
Chris@16: 
Chris@16:         template <>
Chris@16:         struct at_impl<std_tuple_tag>;
Chris@16:     }
Chris@16: 
Chris@101:     namespace detail
Chris@101:     {
Chris@101:         template <typename Sequence, typename N, typename Tag>
Chris@101:         struct at_impl
Chris@101:             : mpl::if_<
Chris@101:                   mpl::less<N, typename extension::size_impl<Tag>::template apply<Sequence>::type>
Chris@101:                 , typename extension::at_impl<Tag>::template apply<Sequence, N>
Chris@101:                 , mpl::empty_base
Chris@101:               >::type
Chris@101:         {};
Chris@101:     }
Chris@101: 
Chris@16:     namespace result_of
Chris@16:     {
Chris@16:         template <typename Sequence, typename N>
Chris@16:         struct at
Chris@101:             : detail::at_impl<Sequence, N, typename detail::tag_of<Sequence>::type>
Chris@16:         {};
Chris@16: 
Chris@16:         template <typename Sequence, int N>
Chris@16:         struct at_c
Chris@16:             : at<Sequence, mpl::int_<N> >
Chris@16:         {};
Chris@16:     }
Chris@16: 
Chris@16: 
Chris@16:     template <typename N, 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<Sequence, N>
Chris@16:         >::type
Chris@16:     at(Sequence& seq)
Chris@16:     {
Chris@16:         return result_of::at<Sequence, N>::call(seq);
Chris@16:     }
Chris@16: 
Chris@16:     template <typename N, typename Sequence>
Chris@101:     BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
Chris@16:     inline typename result_of::at<Sequence const, N>::type
Chris@16:     at(Sequence const& seq)
Chris@16:     {
Chris@16:         return result_of::at<Sequence const, N>::call(seq);
Chris@16:     }
Chris@16: 
Chris@16:     template <int N, 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_c<Sequence, N>
Chris@16:         >::type
Chris@16:     at_c(Sequence& seq)
Chris@16:     {
Chris@16:         return fusion::at<mpl::int_<N> >(seq);
Chris@16:     }
Chris@16: 
Chris@16:     template <int N, typename Sequence>
Chris@101:     BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
Chris@16:     inline typename result_of::at_c<Sequence const, N>::type
Chris@16:     at_c(Sequence const& seq)
Chris@16:     {
Chris@16:         return fusion::at<mpl::int_<N> >(seq);
Chris@16:     }
Chris@16: }}
Chris@16: 
Chris@16: #endif
Chris@16: