/*=============================================================================

    Copyright (c) 2001-2006 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_TAG_OF_09232005_0845)

#define FUSION_TAG_OF_09232005_0845



#include <boost/utility/enable_if.hpp>

#include <boost/type_traits/remove_const.hpp>

#include <boost/fusion/support/tag_of_fwd.hpp>

#include <boost/fusion/support/detail/is_mpl_sequence.hpp>

#include <boost/mpl/has_xxx.hpp>

#include <boost/mpl/identity.hpp>

#include <boost/mpl/assert.hpp>

#include <boost/mpl/bool.hpp>

#include <boost/mpl/if.hpp>

#include <utility>



namespace boost

{

    template <typename T, std::size_t N>

    class array; // forward



    namespace tuples

    {

        struct null_type;



        template <

            class T0, class T1, class T2, class T3, class T4,

            class T5, class T6, class T7, class T8, class T9

        >

        class tuple;



        template <class Head, class Tail>

        struct cons;

    }

}



namespace boost { namespace fusion

{

    struct non_fusion_tag;

    struct mpl_sequence_tag;



    namespace detail

    {

        BOOST_MPL_HAS_XXX_TRAIT_DEF(fusion_tag)



        template<typename Sequence>

        struct is_specialized

          : mpl::false_

        {};



        template <

            class T0, class T1, class T2, class T3, class T4,

            class T5, class T6, class T7, class T8, class T9

        >

        struct is_specialized<tuples::tuple<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9> >

          : mpl::true_

        {};



        template <class Head, class Tail>

        struct is_specialized<tuples::cons<Head, Tail> >

          : mpl::true_

        {};



        template <>

        struct is_specialized<tuples::null_type>

          : mpl::true_

        {};



        template <typename T, std::size_t N>

        struct is_specialized<boost::array<T, N> >

          : mpl::true_

        {};



        template<typename T1, typename T2>

        struct is_specialized<std::pair<T1, T2> >

          : mpl::true_

        {};

    }



    namespace traits

    {

        template <typename Sequence, typename Active>

        struct tag_of

          : mpl::if_< detail::is_mpl_sequence<Sequence>,

              mpl::identity<mpl_sequence_tag>,

              mpl::identity<non_fusion_tag> >::type

        {

            BOOST_MPL_ASSERT_NOT((detail::is_specialized<Sequence>));

        };



        template <typename Sequence>

        struct tag_of<Sequence, typename boost::enable_if<detail::has_fusion_tag<Sequence> >::type>

        {

            typedef typename Sequence::fusion_tag type;

        };

    }



    namespace detail

    {

        template<typename T>

        struct tag_of

            : traits::tag_of<typename remove_const<T>::type>

        {};

    }

}}

#endif

