preprocessor/facilities/va_opt.hpp

0001 # /* **************************************************************************
0002 #  *                                                                          *
0003 #  *     (C) Copyright Edward Diener 2019.
0004 #  *     Distributed under the Boost Software License, Version 1.0. (See
0005 #  *     accompanying file LICENSE_1_0.txt or copy at
0006 #  *     http://www.boost.org/LICENSE_1_0.txt)
0007 #  *                                                                          *
0008 #  ************************************************************************** */
0009 #
0010 # /* See http://www.boost.org for most recent version. */
0011 #
0012 # ifndef BOOST_PREPROCESSOR_FACILITIES_VA_OPT_HPP
0013 # define BOOST_PREPROCESSOR_FACILITIES_VA_OPT_HPP
0014 # include <boost/preprocessor/variadic/has_opt.hpp>
0015 # if BOOST_PP_VARIADIC_HAS_OPT()
0016 # include <boost/preprocessor/control/iif.hpp>
0017 # include <boost/preprocessor/facilities/check_empty.hpp>
0018 # include <boost/preprocessor/tuple/rem.hpp>
0019 # define BOOST_PP_VA_OPT_IMPL(atuple) \
0020     BOOST_PP_TUPLE_REM() atuple       \
0021 /**/
0022 # define BOOST_PP_VA_OPT(rdata,rempty,...)     \
0023     BOOST_PP_VA_OPT_IMPL                       \
0024         (                                      \
0025         BOOST_PP_IIF                           \
0026             (                                  \
0027             BOOST_PP_CHECK_EMPTY(__VA_ARGS__), \
0028             rempty,                            \
0029             rdata                              \
0030             )                                  \
0031         )                                      \
0032 /**/
0033 # endif /* BOOST_PP_VARIADIC_HAS_OPT() */
0034 # endif /* BOOST_PREPROCESSOR_FACILITIES_VA_OPT_HPP */