/*=============================================================================

    Copyright (c) 2001-2006 Joel de Guzman



    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)

==============================================================================*/

#if !defined(FUSION_VALUE_AT_05052005_0229)

#define FUSION_VALUE_AT_05052005_0229



#include <boost/mpl/int.hpp>

#include <boost/fusion/support/tag_of.hpp>



namespace boost { namespace fusion

{

    // Special tags:

    struct sequence_facade_tag;

    struct boost_tuple_tag; // boost::tuples::tuple tag

    struct array_tag; // boost::array tag

    struct mpl_sequence_tag; // mpl sequence tag

    struct std_pair_tag; // std::pair tag



    namespace extension

    {

        template <typename Tag>

        struct value_at_impl

        {

            template <typename Sequence, typename N>

            struct apply;

        };



        template <>

        struct value_at_impl<sequence_facade_tag>

        {

            template <typename Sequence, typename N>

            struct apply : Sequence::template value_at<Sequence, N> {};

        };



        template <>

        struct value_at_impl<boost_tuple_tag>;



        template <>

        struct value_at_impl<array_tag>;



        template <>

        struct value_at_impl<mpl_sequence_tag>;



        template <>

        struct value_at_impl<std_pair_tag>;

    }



    namespace result_of

    {

        template <typename Sequence, typename N>

        struct value_at

            : extension::value_at_impl<typename detail::tag_of<Sequence>::type>::

                template apply<Sequence, N>

        {};



        template <typename Sequence, int N>

        struct value_at_c

            : fusion::result_of::value_at<Sequence, mpl::int_<N> >

        {};

    }

}}



#endif



