#ifndef BOOST_MPL_TAG_HPP_INCLUDED

#define BOOST_MPL_TAG_HPP_INCLUDED

// Copyright Aleksey Gurtovoy 2004

//

// 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)

//

// See http://www.boost.org/libs/mpl for documentation.

// $Id: tag.hpp 49267 2008-10-11 06:19:02Z agurtovoy $

// $Date: 2008-10-11 02:19:02 -0400 (Sat, 11 Oct 2008) $

// $Revision: 49267 $

#include <boost/mpl/eval_if.hpp>

#include <boost/mpl/void.hpp>

#include <boost/mpl/aux_/has_tag.hpp>

#include <boost/mpl/aux_/config/eti.hpp>

namespace boost { namespace mpl {

namespace aux {

template< typename T > struct tag_impl

{

    typedef typename T::tag type;

};

}

template< typename T, typename Default = void_ > struct tag

#if !defined(BOOST_MPL_CFG_MSVC_ETI_BUG)

    : if_< 

          aux::has_tag<T>

        , aux::tag_impl<T>

        , Default

        >::type

{

#else

{

    typedef typename eval_if< 

          aux::has_tag<T>

        , aux::tag_impl<T>

        , Default

        >::type type;

#endif

};

}}

#endif // BOOST_MPL_TAG_HPP_INCLUDED