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

    Copyright (c) 2001-2006 Joel de Guzman

    Copyright (c) 2005-2006 Dan Marsden



    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(BOOST_FUSION_DEQUE_VALUE_AT_IMPL_08122006_0756)

#define BOOST_FUSION_DEQUE_VALUE_AT_IMPL_08122006_0756



#include <boost/fusion/container/deque/detail/keyed_element.hpp>



#include <boost/mpl/equal_to.hpp>

#include <boost/mpl/assert.hpp>



namespace boost { namespace fusion { 



    struct deque_tag;



    namespace extension 

    {

        template<typename T>

        struct value_at_impl;

        

        template<>

        struct value_at_impl<deque_tag>

        {

            template<typename Sequence, typename N>

            struct apply

            {

                typedef typename Sequence::next_up next_up;

                typedef typename Sequence::next_down next_down;

                BOOST_MPL_ASSERT_RELATION(next_down::value, !=, next_up::value);

                

                typedef mpl::plus<next_down, mpl::int_<1> > offset;

                typedef mpl::int_<mpl::plus<N, offset>::value> adjusted_index;

                typedef typename detail::keyed_element_value_at<Sequence, adjusted_index>::type type;

            };

        };

    }

}}



#endif

