third_party/boost/include/boost/fusion/view/nview/detail/prior_impl.hpp

/*=============================================================================
    Copyright (c) 2009 Hartmut Kaiser

    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_NVIEW_PRIOR_IMPL_SEP_24_2009_0142PM)
#define BOOST_FUSION_NVIEW_PRIOR_IMPL_SEP_24_2009_0142PM

#include <boost/mpl/prior.hpp>

namespace boost { namespace fusion
{
    struct nview_iterator_tag;

    template <typename Sequence, typename Pos>
    struct nview_iterator;

    namespace extension
    {
        template <typename Tag>
        struct prior_impl;

        template <>
        struct prior_impl<nview_iterator_tag>
        {
            template <typename Iterator>
            struct apply 
            {
                typedef typename Iterator::first_type::iterator_type first_type;
                typedef typename Iterator::sequence_type sequence_type;

                typedef nview_iterator<sequence_type,
                    typename mpl::prior<first_type>::type> type;

                static type
                call(Iterator const& i)
                {
                    return type(i.seq);
                }
            };
        };
    }

}}

#endif