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// Copyright Aleksey Gurtovoy 2002-2004
// Distributed under the Boost Software License, Version 1.0. 
// (See accompanying file LICENSE_1_0.txt or copy at 
// See 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_<
        , false_
        , msvc_is_class_impl<T>