整理

include/boost/mpl/aux_/msvc_is_class.hpp

@@ -0,0 +1,58 @@
+
+#ifndef BOOST_MPL_AUX_MSVC_IS_CLASS_HPP_INCLUDED
+#define BOOST_MPL_AUX_MSVC_IS_CLASS_HPP_INCLUDED
+
+// Copyright Aleksey Gurtovoy 2002-2004
+//
+// 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/if.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/aux_/type_wrapper.hpp>
+#include <boost/mpl/aux_/yes_no.hpp>
+
+#include <boost/type_traits/is_reference.hpp>
+
+namespace boost { namespace mpl { namespace aux {
+
+template< typename T > struct is_class_helper
+{
+    typedef int (T::* type)();
+};
+
+// MSVC 6.x-specific lightweight 'is_class' implementation; 
+// Distinguishing feature: does not instantiate the type being tested.
+template< typename T >
+struct msvc_is_class_impl
+{
+    template< typename U>
+    static yes_tag  test(type_wrapper<U>*, /*typename*/ is_class_helper<U>::type = 0);
+    static no_tag   test(void const volatile*, ...);
+
+    enum { value = sizeof(test((type_wrapper<T>*)0)) == sizeof(yes_tag) };
+    typedef bool_<value> type;
+};
+
+// agurt, 17/sep/04: have to check for 'is_reference' upfront to avoid ICEs in
+// complex metaprograms
+template< typename T >
+struct msvc_is_class
+    : if_<
+          is_reference<T>
+        , false_
+        , msvc_is_class_impl<T>
+        >::type
+{
+};
+
+}}}
+
+#endif // BOOST_MPL_AUX_MSVC_IS_CLASS_HPP_INCLUDED