ceph/src/boost/boost/mpl/tag.hpp

   1
   2 #ifndef BOOST_MPL_TAG_HPP_INCLUDED
   3 #define BOOST_MPL_TAG_HPP_INCLUDED
   4
   5 // Copyright Aleksey Gurtovoy 2004
   6 //
   7 // Distributed under the Boost Software License, Version 1.0.
   8 // (See accompanying file LICENSE_1_0.txt or copy at
   9 // http://www.boost.org/LICENSE_1_0.txt)
  10 //
  11 // See http://www.boost.org/libs/mpl for documentation.
  12
  13 // $Id$
  14 // $Date$
  15 // $Revision$
  16
  17 #include <boost/mpl/eval_if.hpp>
  18 #include <boost/mpl/void.hpp>
  19 #include <boost/mpl/aux_/has_tag.hpp>
  20 #include <boost/mpl/aux_/config/eti.hpp>
  21
  22 namespace boost { namespace mpl {
  23
  24 namespace aux {
  25 template< typename T > struct tag_impl
  26 {
  27     typedef typename T::tag type;
  28 };
  29 }
  30
  31 template< typename T, typename Default = void_ > struct tag
  32 #if !defined(BOOST_MPL_CFG_MSVC_ETI_BUG)
  33     : if_<
  34           aux::has_tag<T>
  35         , aux::tag_impl<T>
  36         , Default
  37         >::type
  38 {
  39 #else
  40 {
  41     typedef typename eval_if<
  42           aux::has_tag<T>
  43         , aux::tag_impl<T>
  44         , Default
  45         >::type type;
  46
  47 #endif
  48 };
  49
  50 }}
  51
  52 #endif // BOOST_MPL_TAG_HPP_INCLUDED