ext-boost/boost/mpl/aux_/na.hpp
2014-12-07 23:50:51 +01:00

95 lines
1.6 KiB
C++

#ifndef BOOST_MPL_AUX_NA_HPP_INCLUDED
#define BOOST_MPL_AUX_NA_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_/na_fwd.hpp>
#include <boost/mpl/aux_/config/msvc.hpp>
#include <boost/mpl/aux_/config/ctps.hpp>
namespace boost { namespace mpl {
template< typename T >
struct is_na
: false_
{
#if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
using false_::value;
#endif
};
template<>
struct is_na<na>
: true_
{
#if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
using true_::value;
#endif
};
template< typename T >
struct is_not_na
: true_
{
#if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
using true_::value;
#endif
};
template<>
struct is_not_na<na>
: false_
{
#if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
using false_::value;
#endif
};
#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
template< typename T, typename U > struct if_na
{
typedef T type;
};
template< typename U > struct if_na<na,U>
{
typedef U type;
};
#else
template< typename T > struct if_na_impl
{
template< typename U > struct apply
{
typedef T type;
};
};
template<> struct if_na_impl<na>
{
template< typename U > struct apply
{
typedef U type;
};
};
template< typename T, typename U > struct if_na
: if_na_impl<T>::template apply<U>
{
};
#endif
}}
#endif // BOOST_MPL_AUX_NA_HPP_INCLUDED