/*=============================================================================
    Copyright (c) 2011 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(BOOST_FUSION_SEGMENTED_ITERATOR_SEGMENTED_ITERATOR_HPP_INCLUDED)
#define BOOST_FUSION_SEGMENTED_ITERATOR_SEGMENTED_ITERATOR_HPP_INCLUDED

#include <boost/fusion/support/config.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/fusion/sequence/intrinsic_fwd.hpp>
#include <boost/fusion/iterator/iterator_facade.hpp>
#include <boost/fusion/iterator/deref.hpp>
#include <boost/fusion/iterator/deref_data.hpp>
#include <boost/fusion/iterator/key_of.hpp>
#include <boost/fusion/iterator/value_of.hpp>
#include <boost/fusion/iterator/value_of_data.hpp>
#include <boost/fusion/iterator/detail/segmented_equal_to.hpp>

namespace boost {
namespace fusion {
struct nil_;

namespace detail {
template <typename Stack>
struct segmented_next_impl;
}

// A segmented iterator wraps a "context", which is a cons list
// of ranges, the frontmost is range over values and the rest
// are ranges over internal segments.
template <typename Context>
struct segmented_iterator
    : iterator_facade<segmented_iterator<Context>, forward_traversal_tag>
{
    BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED explicit
    segmented_iterator(Context const& ctx)
        : context(ctx)
    {}

    //auto deref(it)
    //{
    //  return deref(begin(car(it.context)))
    //}
    template <typename It>
    struct deref
    {
        typedef
        typename result_of::deref<
        typename It::context_type::car_type::begin_type
        >::type
        type;

        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
        static type
        call(It const& it)
        {
            return *it.context.car.first;
        }
    };

    //auto deref_data(it)
    //{
    //  return deref_data(begin(car(it.context)))
    //}
    template <typename It>
    struct deref_data
    {
        typedef
        typename result_of::deref_data<
        typename It::context_type::car_type::begin_type
        >::type
        type;

        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
        static type
        call(It const& it)
        {
            return fusion::deref_data(it.context.car.first);
        }
    };

    //auto key_of(it)
    //{
    //  return key_of(begin(car(it.context)))
    //}
    template <typename It>
    struct key_of
        : result_of::key_of<typename It::context_type::car_type::begin_type>
    {};

    //auto value_of(it)
    //{
    //  return value_of(begin(car(it.context)))
    //}
    template <typename It>
    struct value_of
        : result_of::value_of<typename It::context_type::car_type::begin_type>
    {};

    //auto value_of_data(it)
    //{
    //  return value_of_data(begin(car(it.context)))
    //}
    template <typename It>
    struct value_of_data
        : result_of::value_of_data<typename It::context_type::car_type::begin_type>
    {};

    // Compare all the segment iterators in each stack, starting with
    // the bottom-most.
    template <
        typename It1
        , typename It2
        , int Size1 = It1::context_type::size::value
        , int Size2 = It2::context_type::size::value
        >
    struct equal_to
        : mpl::false_
    {};

    template <typename It1, typename It2, int Size>
    struct equal_to<It1, It2, Size, Size>
        : detail::segmented_equal_to<
          typename It1::context_type
        , typename It2::context_type
        >
    {};

    template <typename It>
    struct next
    {
        typedef detail::segmented_next_impl<typename It::context_type> impl;
        typedef segmented_iterator<typename impl::type> type;

        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
        static type
        call(It const& it)
        {
            return type(impl::call(it.context));
        }
    };

    typedef Context context_type;
    context_type context;
};

}
}

#endif
