boost/vmd/is_empty_array.hpp

0001
0002 //  (C) Copyright Edward Diener 2011-2015
0003 //  Use, modification and distribution are subject to the Boost Software License,
0004 //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
0005 //  http://www.boost.org/LICENSE_1_0.txt).
0006
0007 #if !defined(BOOST_VMD_IS_EMPTY_ARRAY_HPP)
0008 #define BOOST_VMD_IS_EMPTY_ARRAY_HPP
0009
0010 #include <boost/vmd/detail/setup.hpp>
0011
0012 #if BOOST_PP_VARIADICS
0013
0014 #include <boost/preprocessor/control/iif.hpp>
0015 #include <boost/vmd/is_array.hpp>
0016 #include <boost/vmd/identity.hpp>
0017 #include <boost/vmd/detail/is_empty_array.hpp>
0018
0019 /*
0020
0021   The succeeding comments in this file are in doxygen format.
0022
0023 */
0024
0025 /** \file
0026 */
0027
0028 /** \def BOOST_VMD_IS_EMPTY_ARRAY(sequence)
0029
0030     \brief Tests whether a sequence is an empty Boost PP array.
0031
0032     An empty Boost PP array is a two element tuple where the first
0033     size element is 0 and the second element is a tuple with a single
0034     empty element, ie. '(0,())'.
0035
0036     sequence = a possible empty array
0037
0038     returns = 1 if the sequence is an empty Boost PP array,
0039               0 if it is not.
0040
0041     The macro will generate a preprocessing error if the sequence
0042     is in the form of an array but its first tuple element, instead
0043     of being a number, is a preprocessor token which VMD cannot parse,
0044     as in the example '(&0,())' which is a valid tuple but an invalid
0045     array.
0046
0047 */
0048
0049 #define BOOST_VMD_IS_EMPTY_ARRAY(sequence) \
0050     BOOST_VMD_IDENTITY_RESULT \
0051         ( \
0052         BOOST_PP_IIF \
0053             ( \
0054             BOOST_VMD_IS_ARRAY(sequence), \
0055             BOOST_VMD_DETAIL_IS_EMPTY_ARRAY_SIZE, \
0056             BOOST_VMD_IDENTITY(0) \
0057             ) \
0058         (sequence) \
0059         ) \
0060 /**/
0061
0062 /** \def BOOST_VMD_IS_EMPTY_ARRAY_D(d,sequence)
0063
0064     \brief Tests whether a sequence is an empty Boost PP array. Re-entrant version.
0065
0066     An empty Boost PP array is a two element tuple where the first
0067     size element is 0 and the second element is a tuple with a single
0068     empty element, ie. '(0,())'.
0069
0070     d        = The next available BOOST_PP_WHILE iteration. <br/>
0071     sequence = a possible empty array
0072
0073     returns = 1 if the sequence is an empty Boost PP array,
0074               0 if it is not.
0075
0076     The macro will generate a preprocessing error if the sequence
0077     is in the form of an array but its first tuple element, instead
0078     of being a number, is a preprocessor token which VMD cannot parse,
0079     as in the example '(&0,())' which is a valid tuple but an invalid
0080     array.
0081
0082 */
0083
0084 #define BOOST_VMD_IS_EMPTY_ARRAY_D(d,sequence) \
0085     BOOST_VMD_IDENTITY_RESULT \
0086         ( \
0087         BOOST_PP_IIF \
0088             ( \
0089             BOOST_VMD_IS_ARRAY_D(d,sequence), \
0090             BOOST_VMD_DETAIL_IS_EMPTY_ARRAY_SIZE, \
0091             BOOST_VMD_IDENTITY(0) \
0092             ) \
0093         (sequence) \
0094         ) \
0095 /**/
0096
0097 #endif /* BOOST_PP_VARIADICS */
0098 #endif /* BOOST_VMD_IS_EMPTY_ARRAY_HPP */