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

    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_BEGIN_IMPL_09122006_2034)

#define BOOST_FUSION_DEQUE_BEGIN_IMPL_09122006_2034



#include <boost/fusion/container/deque/deque_iterator.hpp>



#include <boost/mpl/equal_to.hpp>

#include <boost/mpl/if.hpp>



namespace boost { namespace fusion { 



    struct deque_tag;



    namespace extension 

    {

        template<typename T>

        struct begin_impl;

        

        template<>

        struct begin_impl<deque_tag>

        {

            template<typename Sequence>

            struct apply

            {

                typedef typename mpl::if_<

                    mpl::equal_to<typename Sequence::next_down, typename Sequence::next_up>,

                    deque_iterator<Sequence, 0>,

                    deque_iterator<

                    Sequence, mpl::plus<typename Sequence::next_down, mpl::int_<1> >::value> >::type type;

                

                static type call(Sequence& seq)

                {

                    return type(seq);

                }

            };

        };

    }

}}



#endif

