1 2 // Copyright (C) 2009-2012 Lorenzo Caminiti 3 // Distributed under the Boost Software License, Version 1.0 4 // (see accompanying file LICENSE_1_0.txt or a copy at 5 // http://www.boost.org/LICENSE_1_0.txt) 6 // Home at http://www.boost.org/libs/local_function 7 8 #ifndef BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_HPP_ 9 #define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_HPP_ 10 11 // Boost.Preprocessor author P. Mensodines confirmed on an Boost email thread 12 // (subject ``check if a token is a keyword (was "BOOST_PP_IS_UNARY()")'') 13 // that it is OK to used `PP_IS_UNARY()` to check if tokens match predefined 14 // "keyword" as it is done by the macros below (even if `PP_IS_UNARY()` is 15 // technically only part of Boost.Preprocessor private API). 16 #include <boost/preprocessor/detail/is_unary.hpp> 17 #include <boost/preprocessor/cat.hpp> 18 #include <boost/preprocessor/control/iif.hpp> 19 #include <boost/preprocessor/tuple/eat.hpp> 20 21 // PRIVATE // 22 23 #define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_(a, b) \ 24 BOOST_PP_IS_UNARY(BOOST_PP_CAT(a, b)) 25 26 // PUBLIC // 27 28 // `checking_prefix ## tokens` expand to unary (e.g., `(1)`) iff `tokens` start 29 // with keyword to check. 30 #define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_FRONT( \ 31 tokens, checking_prefix) \ 32 BOOST_PP_IIF(BOOST_PP_IS_UNARY(tokens), \ 33 /* on MSVC this check works even if tokens already unary but on */ \ 34 /* C++03 (including GCC) this check on non-unary tokens gives */ \ 35 /* a concatenation error -- so return false is tokens is not unary */ \ 36 0 BOOST_PP_TUPLE_EAT(2) \ 37 , \ 38 BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_ \ 39 )(checking_prefix, tokens) 40 41 // `token ## checking_postfix` expand to unary (e.g., `(1)`) iff `token` is the 42 // keyword to check. This check only works if `token` is a single token, it 43 // will always expand to 0 if token is multiple tokens (e.g., `const *this`). 44 // This check will expand to 0 with no error if `token` starts with a 45 // non-alphanumeric symbol (e.g., `*this`). 46 #define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_BACK( \ 47 token, checking_postfix) \ 48 BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_(token, checking_postfix) 49 50 #endif // #include guard 51 52