| /* 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 |