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Diffstat (limited to 'boost/flyweight/detail/not_placeholder_expr.hpp')
| -rw-r--r-- | boost/flyweight/detail/not_placeholder_expr.hpp | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/boost/flyweight/detail/not_placeholder_expr.hpp b/boost/flyweight/detail/not_placeholder_expr.hpp new file mode 100644 index 0000000000..a62bd09301 --- /dev/null +++ b/boost/flyweight/detail/not_placeholder_expr.hpp @@ -0,0 +1,58 @@ +/* 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 |