advance_impl.hpp

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/*=============================================================================
    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(FUSION_ADVANCE_IMPL_14122005_2015)
#define FUSION_ADVANCE_IMPL_14122005_2015

#include <boost/fusion/iterator/advance.hpp>
#include <boost/mpl/negate.hpp>

namespace boost { namespace fusion {

    struct reverse_view_iterator_tag;

    template <typename Iterator>
    struct reverse_view_iterator;

    namespace extension
    {
        template<typename Tag>
        struct advance_impl;

        template<>
        struct advance_impl<reverse_view_iterator_tag>
        {
            template<typename Iterator, typename Dist>
            struct apply
            {
                typedef typename Iterator::first_type first_type;
                typedef typename mpl::negate<Dist>::type negative_dist;
                typedef typename result_of::advance<first_type, negative_dist>::type advanced_type;
                typedef reverse_view_iterator<advanced_type> type;

                static type
                call(Iterator const& i)
                {
                    return type(boost::fusion::advance<negative_dist>(i.first));
                }
            };
        };
    }
}}

#endif