/*=============================================================================
    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_EQUAL_TO_05052005_1208)
#define FUSION_EQUAL_TO_05052005_1208

#include <boost/fusion/support/config.hpp>
#include <boost/type_traits/is_same.hpp>
#include <boost/fusion/support/tag_of.hpp>
#include <boost/type_traits/add_const.hpp>
#include <boost/fusion/support/is_iterator.hpp>
#include <boost/mpl/and.hpp>
#include <boost/utility/enable_if.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 equal_to_impl
{
    // default implementation
    template <typename I1, typename I2>
    struct apply
        : is_same<typename add_const<I1>::type, typename add_const<I2>::type>
    {};
};

template <>
struct equal_to_impl<iterator_facade_tag>
{
    template <typename It1, typename It2, typename Tag1, typename Tag2>
    struct dispatch : mpl::false_ {};

    template <typename It1, typename It2, typename Tag>
    struct dispatch<It1, It2, Tag, Tag> // same tag
        : It1::template equal_to<It1, It2>
    {};

    template<typename It1, typename It2>
    struct apply : dispatch<It1, It2,
        typename It1::fusion_tag, typename It2::fusion_tag>
    {};
};

template <>
struct equal_to_impl<boost_array_iterator_tag>;

template <>
struct equal_to_impl<mpl_iterator_tag>;

template <>
struct equal_to_impl<std_pair_iterator_tag>;
}

namespace result_of {
template <typename I1, typename I2>
struct equal_to
    : extension::equal_to_impl<typename detail::tag_of<I1>::type>::
      template apply<I1, I2>
{};
}

namespace iterator_operators {
template <typename Iter1, typename Iter2>
BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
inline typename
boost::enable_if<
mpl::and_<is_fusion_iterator<Iter1>, is_fusion_iterator<Iter2> >
, bool
>::type
operator==(Iter1 const&, Iter2 const&)
{
    return result_of::equal_to<Iter1, Iter2>::value;
}

template <typename Iter1, typename Iter2>
BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
inline typename
boost::enable_if<
mpl::and_<is_fusion_iterator<Iter1>, is_fusion_iterator<Iter2> >
, bool
>::type
operator!=(Iter1 const&, Iter2 const&)
{
    return !result_of::equal_to<Iter1, Iter2>::value;
}
}

using iterator_operators::operator==;
using iterator_operators::operator!=;
}
}

#endif
