/*=============================================================================
    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_PRIOR_05042005_1144)
#define FUSION_PRIOR_05042005_1144

#include <boost/fusion/support/config.hpp>
#include <boost/fusion/support/tag_of.hpp>

namespace boost {
namespace fusion {
// 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 prior_impl
{
    template <typename Iterator>
    struct apply {};
};

template <>
struct prior_impl<iterator_facade_tag>
{
    template <typename Iterator>
    struct apply : Iterator::template prior<Iterator> {};
};

template <>
struct prior_impl<boost_array_iterator_tag>;

template <>
struct prior_impl<mpl_iterator_tag>;

template <>
struct prior_impl<std_pair_iterator_tag>;
}

namespace result_of {
template <typename Iterator>
struct prior
    : extension::prior_impl<typename detail::tag_of<Iterator>::type>::
      template apply<Iterator>
{};
}

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

#endif
