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/* Copyright 2006-2009 Joaquin M Lopez Munoz.
* 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/flyweight for library home page.
*/
#ifndef BOOST_FLYWEIGHT_DETAIL_IS_PLACEHOLDER_EXPR_HPP
#define BOOST_FLYWEIGHT_DETAIL_IS_PLACEHOLDER_EXPR_HPP
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/type_traits/is_same.hpp>
#include <boost/mpl/apply.hpp>
#include <boost/mpl/aux_/lambda_support.hpp>
#include <boost/mpl/not.hpp>
#include <boost/preprocessor/facilities/intercept.hpp>
#include <boost/preprocessor/repetition/enum_params.hpp>
namespace boost{
namespace flyweights{
namespace detail{
/* is_placeholder_expression<T> indicates whether T is an
* MPL placeholder expression.
*/
template<typename T>
struct is_placeholder_expression_helper
{
template<
BOOST_PP_ENUM_PARAMS(
BOOST_MPL_LIMIT_METAFUNCTION_ARITY,typename BOOST_PP_INTERCEPT)
>
struct apply{
typedef int type;
};
BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_placeholder_expression_helper,(T))
};
template<typename T>
struct is_placeholder_expression:
mpl::not_<is_same<
typename mpl::apply<
is_placeholder_expression_helper<T>,
BOOST_PP_ENUM_PARAMS(
BOOST_MPL_LIMIT_METAFUNCTION_ARITY,int BOOST_PP_INTERCEPT)
>::type,
int
> >
{};
} /* namespace flyweights::detail */
} /* namespace flyweights */
} /* namespace boost */
#endif
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