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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 |