/* Copyright 2006-2008 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_NOT_PLACEHOLDER_EXPR_HPP | |
#define BOOST_FLYWEIGHT_DETAIL_NOT_PLACEHOLDER_EXPR_HPP | |
#if defined(_MSC_VER)&&(_MSC_VER>=1200) | |
#pragma once | |
#endif | |
/* BOOST_FLYWEIGHT_NOT_A_PLACEHOLDER_EXPRESSION can be inserted at the end | |
* of a class template parameter declaration: | |
* template< | |
* typename X0,...,typename Xn | |
* BOOST_FLYWEIGHT_NOT_A_PLACEHOLDER_EXPRESSION | |
* > | |
* struct foo... | |
* to prevent instantiations from being treated as MPL placeholder | |
* expressions in the presence of placeholder arguments; this is useful | |
* to avoid masking of a metafunction class nested ::apply during | |
* MPL invocation. | |
*/ | |
#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */ | |
#include <boost/detail/workaround.hpp> | |
#if BOOST_WORKAROUND(__GNUC__, <4)||\ | |
BOOST_WORKAROUND(__GNUC__,==4)&&(__GNUC_MINOR__<2) | |
/* The default trick on which the macro is based, namely adding a int=0 | |
* defaulted template parameter, does not work in GCC prior to 4.2 due to | |
* an unfortunate compiler non-standard extension, as explained in | |
* http://lists.boost.org/boost-users/2007/07/29866.php | |
* We resort to an uglier technique, adding defaulted template parameters | |
* so as to exceed BOOST_MPL_LIMIT_METAFUNCTION_ARITY. | |
*/ | |
#include <boost/mpl/limits/arity.hpp> | |
#include <boost/preprocessor/facilities/intercept.hpp> | |
#include <boost/preprocessor/repetition/enum_trailing_params.hpp> | |
#define BOOST_FLYWEIGHT_NOT_A_PLACEHOLDER_EXPRESSION \ | |
BOOST_PP_ENUM_TRAILING_PARAMS( \ | |
BOOST_MPL_LIMIT_METAFUNCTION_ARITY,typename=int BOOST_PP_INTERCEPT) | |
#define BOOST_FLYWEIGHT_NOT_A_PLACEHOLDER_EXPRESSION_DEF \ | |
BOOST_PP_ENUM_TRAILING_PARAMS( \ | |
BOOST_MPL_LIMIT_METAFUNCTION_ARITY,typename BOOST_PP_INTERCEPT) | |
#else | |
#define BOOST_FLYWEIGHT_NOT_A_PLACEHOLDER_EXPRESSION ,int=0 | |
#define BOOST_FLYWEIGHT_NOT_A_PLACEHOLDER_EXPRESSION_DEF ,int | |
#endif | |
#endif |