整理

include/boost/mpl/empty_base.hpp

@@ -0,0 +1,63 @@
+
+#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