boost/proto/detail/remove_typename.hpp
//============================================================================== // Copyright 2003 - 2011 LASMEA UMR 6602 CNRS/Univ. Clermont II // Copyright 2009 - 2011 LRI UMR 8623 CNRS/Univ Paris Sud XI // Copyright 2011 Eric Niebler // // Distributed under the Boost Software License, Version 1.0. // See accompanying file LICENSE.txt or copy at // http://www.boost.org/LICENSE_1_0.txt //============================================================================== #ifndef BOOST_PROTO_PREPROCESSOR_REMOVE_TYPENAME_HPP_INCLUDED #define BOOST_PROTO_PREPROCESSOR_REMOVE_TYPENAME_HPP_INCLUDED /*! * \file * \brief Defines the BOOST_PROTO_REMOVE_TYPENAME macro */ #include <boost/preprocessor/cat.hpp> #include <boost/preprocessor/expand.hpp> #include <boost/preprocessor/tuple/eat.hpp> #include <boost/preprocessor/control/iif.hpp> #include <boost/preprocessor/detail/is_unary.hpp> //============================================================================== // Boost.Preprocessor author P. Mensodines confirmed on an Boost email thread // (subject ``check if a token is a keyword (was "BOOST_PP_IS_UNARY()")'') // that it is OK to used `PP_IS_UNARY()` to check if tokens match predefined // "keyword" as it is done by the macros below (even if `PP_IS_UNARY()` is // technically only part of Boost.Preprocessor private API). //============================================================================== //============================================================================== // `checking_prefix ## tokens` expand to unary (e.g., `(1)`) iff `tokens` start // with keyword to check. //============================================================================== #define BOOST_PROTO_DETAILS_KEYWORD_FACILITY_IS_FRONT(T, CHECKING_PREFIX) \ BOOST_PP_IS_UNARY(BOOST_PP_CAT(CHECKING_PREFIX, T)) \ /**/ //============================================================================== // `is_front_macro(tokens)` is 1 iff `tokens` start with keyword to remove. // `removing_prefix ## <keyword-to-remove>` must expand to nothing. //============================================================================== #define BOOST_PROTO_DETAILS_KEYWORD_FACILITY_REMOVE_FRONT(TOKENS, IS_FRONT_MACRO, REMOVING_PREFIX) \ BOOST_PP_EXPAND( /* without EXPAND doesn't expand on MSVC */ \ BOOST_PP_IIF( \ IS_FRONT_MACRO(TOKENS) \ , BOOST_PP_CAT \ , TOKENS BOOST_PP_TUPLE_EAT(2) \ )(REMOVING_PREFIX, TOKENS) \ ) \ /**/ #define BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_IS_typename (1) /* unary */ #define typename_BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_IS (1) /* unary */ #define BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_REMOVE_typename /* nothing */ #define typename_BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_REMOVE /* nothing */ #define BOOST_PROTO_DETAILS_KEYWORD_IS_TYPENAME_FRONT(TOKENS) \ BOOST_PROTO_DETAILS_KEYWORD_FACILITY_IS_FRONT(TOKENS, BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_IS_) \ /**/ //============================================================================== /*! * \ingroup preprocessor * For any symbol \c X, this macro returns the same symbol from which a potential * leading \c typename keyword has been removed. If no typename keyword is present, * this macros evaluates to \c X itself without error. * * The original implementation of this macro is from Lorenzo Caminiti. * * \param X Symbol to remove \c typename from */ //============================================================================== #define BOOST_PROTO_REMOVE_TYPENAME(X) \ BOOST_PROTO_DETAILS_KEYWORD_FACILITY_REMOVE_FRONT( \ X \ , BOOST_PROTO_DETAILS_KEYWORD_IS_TYPENAME_FRONT \ , BOOST_PROTO_DETAILS_KEYWORD_TYPENAME_REMOVE_ \ ) \ /**/ #endif