66 lines
1.5 KiB
C++
66 lines
1.5 KiB
C++
/* Copyright 2006-2009 Joaquin M Lopez Munoz.
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*
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* See http://www.boost.org/libs/flyweight for library home page.
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*/
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#ifndef BOOST_FLYWEIGHT_DETAIL_IS_PLACEHOLDER_EXPR_HPP
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#define BOOST_FLYWEIGHT_DETAIL_IS_PLACEHOLDER_EXPR_HPP
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#if defined(_MSC_VER)
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#pragma once
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#endif
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#include <boost/type_traits/is_same.hpp>
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#include <boost/mpl/apply.hpp>
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#include <boost/mpl/aux_/lambda_support.hpp>
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#include <boost/mpl/not.hpp>
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#include <boost/preprocessor/facilities/intercept.hpp>
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#include <boost/preprocessor/repetition/enum_params.hpp>
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namespace boost{
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namespace flyweights{
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namespace detail{
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/* is_placeholder_expression<T> indicates whether T is an
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* MPL placeholder expression.
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*/
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template<typename T>
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struct is_placeholder_expression_helper
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{
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template<
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BOOST_PP_ENUM_PARAMS(
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BOOST_MPL_LIMIT_METAFUNCTION_ARITY,typename BOOST_PP_INTERCEPT)
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>
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struct apply{
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typedef int type;
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};
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BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_placeholder_expression_helper,(T))
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};
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template<typename T>
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struct is_placeholder_expression:
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mpl::not_<is_same<
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typename mpl::apply<
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is_placeholder_expression_helper<T>,
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BOOST_PP_ENUM_PARAMS(
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BOOST_MPL_LIMIT_METAFUNCTION_ARITY,int BOOST_PP_INTERCEPT)
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>::type,
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int
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> >
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{};
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} /* namespace flyweights::detail */
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} /* namespace flyweights */
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} /* namespace boost */
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#endif
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