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Fixes for empty tuple processing

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Edward Diener
2014-04-27 12:00:13 -04:00
parent 21ccb35814
commit f80bb83f3b
5 changed files with 87 additions and 6 deletions
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27
include/boost/preprocessor/tuple/elem.hpp
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@ -8,7 +8,7 @@
# */
#
# /* Revised by Paul Mensonides (2002-2011) */
# /* Revised by Edward Diener (2011) */
# /* Revised by Edward Diener (2011,2014) */
#
# /* See http://www.boost.org for most recent version. */
#
@ -21,15 +21,38 @@
# include <boost/preprocessor/tuple/rem.hpp>
# include <boost/preprocessor/variadic/elem.hpp>
#
# if BOOST_PP_VARIADICS && BOOST_PP_VARIADICS_MSVC
# include <boost/preprocessor/comparison/equal.hpp>
# include <boost/preprocessor/control/iif.hpp>
# include <boost/preprocessor/tuple/size.hpp>
# endif
#
# if BOOST_PP_VARIADICS
# if BOOST_PP_VARIADICS_MSVC
# define BOOST_PP_TUPLE_ELEM(...) BOOST_PP_TUPLE_ELEM_I(BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_ELEM_O_, __VA_ARGS__), (__VA_ARGS__))
# define BOOST_PP_TUPLE_ELEM_I(m, args) BOOST_PP_TUPLE_ELEM_II(m, args)
# define BOOST_PP_TUPLE_ELEM_II(m, args) BOOST_PP_CAT(m ## args,)
/*
Use BOOST_PP_TUPLE_ELEM_O_2_CAT if it is a single element tuple ( which might be empty )
else use BOOST_PP_REM. This fixes a VC++ problem with an empty tuple and BOOST_PP_TUPLE_ELEM
functionality.
*/
# define BOOST_PP_TUPLE_ELEM_O_2_CAT(...) BOOST_PP_CAT(__VA_ARGS__,)
# define BOOST_PP_TUPLE_ELEM_O_2_SINGLE(n, tuple) BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_TUPLE_ELEM_O_2_CAT tuple)
# define BOOST_PP_TUPLE_ELEM_O_2_ANY(n, tuple) BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_REM tuple)
# define BOOST_PP_TUPLE_ELEM_O_2(n, tuple) \
BOOST_PP_IIF \
( \
BOOST_PP_EQUAL(BOOST_PP_TUPLE_SIZE(tuple),1), \
BOOST_PP_TUPLE_ELEM_O_2_SINGLE, \
BOOST_PP_TUPLE_ELEM_O_2_ANY \
) \
(n, tuple) \
/**/
# else
# define BOOST_PP_TUPLE_ELEM(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_ELEM_O_, __VA_ARGS__)(__VA_ARGS__)
# define BOOST_PP_TUPLE_ELEM_O_2(n, tuple) BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_REM tuple)
# endif
# define BOOST_PP_TUPLE_ELEM_O_2(n, tuple) BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_REM tuple)
# define BOOST_PP_TUPLE_ELEM_O_3(size, n, tuple) BOOST_PP_TUPLE_ELEM_O_2(n, tuple)
# else
# if BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MSVC()