diff options
Diffstat (limited to 'boost/vmd/is_empty.hpp')
-rw-r--r-- | boost/vmd/is_empty.hpp | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/boost/vmd/is_empty.hpp b/boost/vmd/is_empty.hpp new file mode 100644 index 0000000000..951c98bf6d --- /dev/null +++ b/boost/vmd/is_empty.hpp @@ -0,0 +1,95 @@ + +// (C) Copyright Edward Diener 2011-2015 +// Use, modification and distribution are subject to the Boost Software License, +// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at +// http://www.boost.org/LICENSE_1_0.txt). + +#if !defined(BOOST_VMD_IS_EMPTY_HPP) +#define BOOST_VMD_IS_EMPTY_HPP + +#include <boost/vmd/detail/setup.hpp> + +#if BOOST_PP_VARIADICS + +#include <boost/preprocessor/punctuation/is_begin_parens.hpp> +#include <boost/vmd/detail/is_empty.hpp> + +/* + + The succeeding comments in this file are in doxygen format. + +*/ + +/** \file +*/ + +/** \def BOOST_VMD_IS_EMPTY(...) + + \brief Tests whether its input is empty or not. + + The macro checks to see if the input is empty or not. + It returns 1 if the input is empty, else returns 0. + + The macro is a variadic macro taking any input. + For the VC++8 compiler (VS2005) the macro takes a single parameter of input to check. + + The macro is not perfect, and can not be so. The problem + area is if the input to be checked is a function-like + macro name, in which case either a compiler error can result + or a false result can occur. + + This macro is a replacement, using variadic macro support, + for the undocumented macro BOOST_PP_IS_EMPTY in the Boost + PP library. The code is taken from a posting by Paul Mensonides + of a variadic version for BOOST_PP_IS_EMPTY, and changed + in order to also support VC++. + + .... = variadic input, for VC++8 this must be a single parameter + + returns = 1 if the input is empty, 0 if it is not + + It is recommended to append BOOST_PP_EMPTY() to whatever input + is being tested in order to avoid possible warning messages + from some compilers about no parameters being passed to the macro + when the input is truly empty. + +*/ + +#if BOOST_VMD_MSVC_V8 + +#define BOOST_VMD_IS_EMPTY(sequence) \ + BOOST_VMD_DETAIL_IS_EMPTY_IIF \ + ( \ + BOOST_PP_IS_BEGIN_PARENS \ + ( \ + sequence \ + ) \ + ) \ + ( \ + BOOST_VMD_DETAIL_IS_EMPTY_GEN_ZERO, \ + BOOST_VMD_DETAIL_IS_EMPTY_PROCESS \ + ) \ + (sequence) \ +/**/ + +#else + +#define BOOST_VMD_IS_EMPTY(...) \ + BOOST_VMD_DETAIL_IS_EMPTY_IIF \ + ( \ + BOOST_PP_IS_BEGIN_PARENS \ + ( \ + __VA_ARGS__ \ + ) \ + ) \ + ( \ + BOOST_VMD_DETAIL_IS_EMPTY_GEN_ZERO, \ + BOOST_VMD_DETAIL_IS_EMPTY_PROCESS \ + ) \ + (__VA_ARGS__) \ +/**/ + +#endif /* BOOST_VMD_MSVC_V8 */ + +#endif /* BOOST_PP_VARIADICS */ +#endif /* BOOST_VMD_IS_EMPTY_HPP */ |