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

    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_09172005_1146)
#define FUSION_ADVANCE_09172005_1146

#include <boost/fusion/support/config.hpp>
#include <boost/fusion/iterator/detail/advance.hpp>
#include <boost/fusion/support/category_of.hpp>

#include <boost/mpl/int.hpp>
#include <boost/mpl/assert.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/fusion/support/tag_of.hpp>

namespace boost {
namespace fusion {
struct random_access_traversal_tag;

// Special tags:
struct iterator_facade_tag; // iterator facade tag
struct boost_array_iterator_tag; // boost::array iterator tag
struct mpl_iterator_tag; // mpl sequence iterator tag
struct std_pair_iterator_tag; // std::pair iterator tag

namespace extension {
template <typename Tag>
struct advance_impl
{
    // default implementation
    template <typename Iterator, typename N>
    struct apply :
        mpl::if_c<
    (N::value > 0)
    , advance_detail::forward<Iterator, N::value>
    , advance_detail::backward<Iterator, N::value>
    >::type
    {
        BOOST_MPL_ASSERT_NOT((traits::is_random_access<Iterator>));
    };
};

template <>
struct advance_impl<iterator_facade_tag>
{
    template <typename Iterator, typename N>
    struct apply : Iterator::template advance<Iterator, N> {};
};

template <>
struct advance_impl<boost_array_iterator_tag>;

template <>
struct advance_impl<mpl_iterator_tag>;

template <>
struct advance_impl<std_pair_iterator_tag>;
}

namespace result_of {
template <typename Iterator, int N>
struct advance_c
    : extension::advance_impl<typename detail::tag_of<Iterator>::type>::template apply<Iterator, mpl::int_<N> >
{};

template <typename Iterator, typename N>
struct advance
    : extension::advance_impl<typename detail::tag_of<Iterator>::type>::template apply<Iterator, N>
{};
}

template <int N, typename Iterator>
BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
inline typename result_of::advance_c<Iterator, N>::type const
advance_c(Iterator const& i)
{
    return result_of::advance_c<Iterator, N>::call(i);
}

template<typename N, typename Iterator>
BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
inline typename result_of::advance<Iterator, N>::type const
advance(Iterator const& i)
{
    return result_of::advance<Iterator, N>::call(i);
}

}
} // namespace boost::fusion

#endif
