#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.

 // $Source: /cvsroot/boost/boost/boost/mpl/tag.hpp,v $

 // $Date: 2004/09/02 15:40:42 $

 // $Revision: 1.2 $

 #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