//-----------------------------------------------------------------------------

// boost variant/detail/over_sequence.hpp header file

// See http://www.boost.org for updates, documentation, and revision history.

//-----------------------------------------------------------------------------

//

// Copyright (c) 2003

// Eric Friedman

//

// Portions Copyright (C) 2002 David Abrahams

//

// 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)

#ifndef BOOST_VARIANT_DETAIL_OVER_SEQUENCE_HPP

#define BOOST_VARIANT_DETAIL_OVER_SEQUENCE_HPP

#include "boost/mpl/aux_/config/ctps.hpp"

#if defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)

#   include "boost/mpl/eval_if.hpp"

#   include "boost/mpl/bool.hpp"

#   include "boost/mpl/identity.hpp"

#   include "boost/type.hpp"

#endif

namespace boost {

namespace detail { namespace variant {

///////////////////////////////////////////////////////////////////////////////

// (detail) class over_sequence

//

// Wrapper used to indicate bounded types for variant are from type sequence.

//

template <typename Types>

struct over_sequence

{

    typedef Types type;

};

///////////////////////////////////////////////////////////////////////////////

// (detail) metafunction is_over_sequence (modeled on code by David Abrahams)

//

// Indicates whether the specified type is of form over_sequence<...> or not.

//

#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)

template <typename T>

struct is_over_sequence

    : mpl::false_

{

};

template <typename Types>

struct is_over_sequence< over_sequence<Types> >

    : mpl::true_

{

};

#else // defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)

typedef char (&yes_over_sequence_t)[1];

typedef char (&no_over_sequence_t)[2];

no_over_sequence_t is_over_sequence_test(...);

template<typename T>

yes_over_sequence_t is_over_sequence_test(

      type< ::boost::detail::variant::over_sequence<T> >

    );

template<typename T>

struct is_over_sequence_impl

{

    BOOST_STATIC_CONSTANT(bool, value = (

          sizeof(is_over_sequence_test(type<T>()))

          == sizeof(yes_over_sequence_t)

        ));

};

template <typename T>

struct is_over_sequence

    : mpl::bool_<

          ::boost::detail::variant::is_over_sequence_impl<T>::value

        >

{

};

#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION workaround

}} // namespace detail::variant

} // namespace boost

#endif // BOOST_VARIANT_DETAIL_OVER_SEQUENCE_HPP