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3rdparty/boost_1_81_0/boost/mpl/empty_base.hpp 1.37 KB
63e88f80   Hu Chunming   提交三方库
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  #ifndef BOOST_MPL_EMPTY_BASE_HPP_INCLUDED
  #define BOOST_MPL_EMPTY_BASE_HPP_INCLUDED
  
  // Copyright Aleksey Gurtovoy 2001-2004
  //
  // 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.
  
  // $Id$
  // $Date$
  // $Revision$
  
  #include <boost/mpl/bool.hpp>
  #include <boost/mpl/aux_/config/msvc.hpp>
  #include <boost/mpl/aux_/config/workaround.hpp>
  #include <boost/mpl/aux_/lambda_support.hpp>
  
  #include <boost/type_traits/integral_constant.hpp>
  #include <boost/type_traits/is_empty.hpp>
  
  namespace boost { namespace mpl {
  
  // empty base class, guaranteed to have no members; inheritance from
  // 'empty_base' through the 'inherit' metafunction is a no-op - see 
  // "mpl/inherit.hpp> header for the details
  struct empty_base {};
  
  template< typename T >
  struct is_empty_base
      : false_
  {
  #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
      using false_::value;
  #endif
  };
  
  template<>
  struct is_empty_base<empty_base>
      : true_
  {
  #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
      using true_::value;
  #endif
  };
  
  }}
  
  namespace boost {
  
  template<> struct is_empty< mpl::empty_base >
      : public ::boost::integral_constant<bool,true>
  {
  public:
      BOOST_MPL_AUX_LAMBDA_SUPPORT_SPEC(1,is_empty,(mpl::empty_base))
  };
  
  }
  
  #endif // BOOST_MPL_EMPTY_BASE_HPP_INCLUDED