summaryrefslogtreecommitdiff
path: root/boost/local_function/detail/preprocessor/keyword/facility/is.hpp
diff options
context:
space:
mode:
Diffstat (limited to 'boost/local_function/detail/preprocessor/keyword/facility/is.hpp')
-rw-r--r--boost/local_function/detail/preprocessor/keyword/facility/is.hpp51
1 files changed, 51 insertions, 0 deletions
diff --git a/boost/local_function/detail/preprocessor/keyword/facility/is.hpp b/boost/local_function/detail/preprocessor/keyword/facility/is.hpp
new file mode 100644
index 0000000000..a5a1151a61
--- /dev/null
+++ b/boost/local_function/detail/preprocessor/keyword/facility/is.hpp
@@ -0,0 +1,51 @@
+
+// Copyright (C) 2009-2012 Lorenzo Caminiti
+// Distributed under the Boost Software License, Version 1.0
+// (see accompanying file LICENSE_1_0.txt or a copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+// Home at http://www.boost.org/libs/local_function
+
+#ifndef BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_HPP_
+#define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_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).
+#include <boost/preprocessor/detail/is_unary.hpp>
+#include <boost/preprocessor/cat.hpp>
+#include <boost/preprocessor/control/iif.hpp>
+#include <boost/preprocessor/tuple/eat.hpp>
+
+// PRIVATE //
+
+#define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_(a, b) \
+ BOOST_PP_IS_UNARY(BOOST_PP_CAT(a, b))
+
+// PUBLIC //
+
+// `checking_prefix ## tokens` expand to unary (e.g., `(1)`) iff `tokens` start
+// with keyword to check.
+#define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_FRONT( \
+ tokens, checking_prefix) \
+ BOOST_PP_IIF(BOOST_PP_IS_UNARY(tokens), \
+ /* on MSVC this check works even if tokens already unary but on */ \
+ /* C++03 (including GCC) this check on non-unary tokens gives */ \
+ /* a concatenation error -- so return false is tokens is not unary */ \
+ 0 BOOST_PP_TUPLE_EAT(2) \
+ , \
+ BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_ \
+ )(checking_prefix, tokens)
+
+// `token ## checking_postfix` expand to unary (e.g., `(1)`) iff `token` is the
+// keyword to check. This check only works if `token` is a single token, it
+// will always expand to 0 if token is multiple tokens (e.g., `const *this`).
+// This check will expand to 0 with no error if `token` starts with a
+// non-alphanumeric symbol (e.g., `*this`).
+#define BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_BACK( \
+ token, checking_postfix) \
+ BOOST_LOCAL_FUNCTION_DETAIL_PP_KEYWORD_FACILITY_IS_(token, checking_postfix)
+
+#endif // #include guard
+