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// Copyright (C) 2009-2012 Lorenzo Caminiti
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// Distributed under the Boost Software License, Version 1.0
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// (see accompanying file LICENSE_1_0.txt or a copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// Home at http://www.boost.org/libs/local_function
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#ifndef BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_HPP_
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#define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_HPP_
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// Boost.Preprocessor author P. Mensodines confirmed on an Boost email thread
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// (subject ``check if a token is a keyword (was "BOOST_PP_IS_UNARY()")'')
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// that it is OK to used `PP_IS_UNARY()` to check if tokens match predefined
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// "keyword" as it is done by the macros below (even if `PP_IS_UNARY()` is
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// technically only part of Boost.Preprocessor private API).
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#include <boost/preprocessor/detail/is_unary.hpp>
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#include <boost/preprocessor/cat.hpp>
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#include <boost/preprocessor/control/iif.hpp>
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#include <boost/preprocessor/tuple/eat.hpp>
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// PRIVATE //
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#define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_(a, b) \
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BOOST_PP_IS_UNARY(BOOST_PP_CAT(a, b))
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// PUBLIC //
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// `checking_prefix ## tokens` expand to unary (e.g., `(1)`) iff `tokens` start
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// with keyword to check.
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#define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_FRONT( \
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tokens, checking_prefix) \
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BOOST_PP_IIF(BOOST_PP_IS_UNARY(tokens), \
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/* on MSVC this check works even if tokens already unary but on */ \
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/* C++03 (including GCC) this check on non-unary tokens gives */ \
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/* a concatenation error -- so return false is tokens is not unary */ \
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0 BOOST_PP_TUPLE_EAT(2) \
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, \
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BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_ \
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)(checking_prefix, tokens)
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// `token ## checking_postfix` expand to unary (e.g., `(1)`) iff `token` is the
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// keyword to check. This check only works if `token` is a single token, it
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// will always expand to 0 if token is multiple tokens (e.g., `const *this`).
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// This check will expand to 0 with no error if `token` starts with a
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// non-alphanumeric symbol (e.g., `*this`).
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#define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_BACK( \
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token, checking_postfix) \
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BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_(token, checking_postfix)
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#endif // #include guard
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