seq/detail/is_empty.hpp

0001 # /* **************************************************************************
0002 #  *                                                                          *
0003 #  *     (C) Copyright Edward Diener 2015.
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_SEQ_DETAIL_IS_EMPTY_HPP
0013 # define BOOST_PREPROCESSOR_SEQ_DETAIL_IS_EMPTY_HPP
0014 #
0015 # include <boost/preprocessor/config/config.hpp>
0016 # include <boost/preprocessor/arithmetic/dec.hpp>
0017 # include <boost/preprocessor/logical/bool.hpp>
0018 # include <boost/preprocessor/logical/compl.hpp>
0019 # include <boost/preprocessor/seq/size.hpp>
0020 #
0021 /* An empty seq is one that is just BOOST_PP_SEQ_NIL */
0022 #
0023 # define BOOST_PP_SEQ_DETAIL_IS_EMPTY(seq) \
0024     BOOST_PP_COMPL \
0025         ( \
0026         BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq) \
0027         ) \
0028 /**/
0029 #
0030 # define BOOST_PP_SEQ_DETAIL_IS_EMPTY_SIZE(size) \
0031     BOOST_PP_COMPL \
0032         ( \
0033         BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY_SIZE(size) \
0034         ) \
0035 /**/
0036 #
0037 # define BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq) \
0038     BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY_SIZE(BOOST_PP_SEQ_DETAIL_EMPTY_SIZE(seq)) \
0039 /**/
0040 #
0041 # define BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY_SIZE(size) \
0042     BOOST_PP_BOOL(size) \
0043 /**/
0044 #
0045 # define BOOST_PP_SEQ_DETAIL_EMPTY_SIZE(seq) \
0046     BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(seq (nil))) \
0047 /**/
0048 #
0049 # endif