local_function/aux_/symbol.hpp

0001
0002 // Copyright (C) 2009-2012 Lorenzo Caminiti
0003 // Distributed under the Boost Software License, Version 1.0
0004 // (see accompanying file LICENSE_1_0.txt or a copy at
0005 // http://www.boost.org/LICENSE_1_0.txt)
0006 // Home at http://www.boost.org/libs/local_function
0007
0008 #ifndef BOOST_LOCAL_FUNCTION_AUX_SYMBOL_HPP_
0009 #define BOOST_LOCAL_FUNCTION_AUX_SYMBOL_HPP_
0010
0011 #include <boost/preprocessor/cat.hpp>
0012 #include <boost/preprocessor/seq/cat.hpp>
0013 #include <boost/preprocessor/seq/transform.hpp>
0014
0015 // PRIVATE //
0016
0017 // NOTE: INFIX is used to separate symbols concatenated together. Some of these
0018 // symbols are user-defined so they can be anything. Because they can contain
0019 // underscore `_` and/or start with capital letters, it is NOT safe for the
0020 // INFIX to be the underscore `_` character because that could lead to library
0021 // defined symbols containing double underscores `__` or a leading underscore
0022 // (followed or not by a capital letter) in the global namespace. All these
0023 // symbols are reserved by the C++ standard: (1) "each name that contains a
0024 // double underscore (_ _) or begins with an underscore followed by an
0025 // uppercase letter is reserved to the implementation" and (2) "each name that
0026 // begins with an underscore is reserved to the implementation for use as a
0027 // name in the global namespace".
0028 #define BOOST_LOCAL_FUNCTION_AUX_SYMBOL_INFIX_ X // `X` used as separator.
0029
0030 #define BOOST_LOCAL_FUNCTION_AUX_SYMBOL_PREFIX_ boost_local_function_aux
0031
0032 #define BOOST_LOCAL_FUNCTION_AUX_SYMBOL_POSTFIX_(s, unused, tokens) \
0033     BOOST_PP_CAT(tokens, BOOST_LOCAL_FUNCTION_AUX_SYMBOL_INFIX_)
0034
0035 // PUBLIC //
0036
0037 // Prefixes this library reserved symbol.
0038 #define BOOST_LOCAL_FUNCTION_AUX_SYMBOL(seq) \
0039     BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_TRANSFORM( \
0040             BOOST_LOCAL_FUNCTION_AUX_SYMBOL_POSTFIX_, \
0041             ~, (BOOST_LOCAL_FUNCTION_AUX_SYMBOL_PREFIX_) seq ))
0042
0043 // Postfixes this library reserved symbol.
0044 #define BOOST_LOCAL_FUNCTION_AUX_SYMBOL_POSTFIX(seq) \
0045     BOOST_PP_SEQ_CAT(BOOST_PP_SEQ_TRANSFORM( \
0046             BOOST_LOCAL_FUNCTION_AUX_SYMBOL_POSTFIX_, \
0047             ~, seq (BOOST_LOCAL_FUNCTION_AUX_SYMBOL_PREFIX_) ))
0048
0049 #endif // #include guard
0050