/*=============================================================================
    Copyright (c) 2001-2011 Joel de Guzman
    Copyright (c) 2005 Eric Niebler

    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_NEXT_IMPL_07172005_0836)
#define FUSION_NEXT_IMPL_07172005_0836

#include <boost/fusion/support/config.hpp>
#include <boost/fusion/iterator/next.hpp>
#include <boost/fusion/iterator/equal_to.hpp>
#include <boost/mpl/eval_if.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/type_traits/is_const.hpp>
#include <boost/type_traits/add_const.hpp>

namespace boost {
namespace fusion {
struct cons_iterator_tag;

template <typename Cons>
struct cons_iterator;

namespace extension {
template <typename Tag>
struct next_impl;

template <>
struct next_impl<cons_iterator_tag>
{
    template <typename Iterator>
    struct apply
    {
        typedef typename Iterator::cons_type cons_type;
        typedef typename cons_type::cdr_type cdr_type;

        typedef cons_iterator<
        typename mpl::eval_if<
        is_const<cons_type>
        , add_const<cdr_type>
        , mpl::identity<cdr_type>
        >::type>
        type;

        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
        static type
        call(Iterator const& i)
        {
            return type(i.cons.cdr);
        }
    };
};
}
}
}

#endif
