In C++20 variadic data can be empty. This means that BOOST_PP_VARIADIC_SIZE now returns 0 for empty data instead of 1, and that conversions to and from empty variadic data and lists or arrays, which can be empty, work properly.

2020-06-29 21:57:23 -04:00
parent ffb26db146
commit 3ac4c915a3
14 changed files with 173 additions and 16 deletions
--- a/include/boost/preprocessor/tuple/reverse.hpp
+++ b/include/boost/preprocessor/tuple/reverse.hpp
@ -17,9 +17,11 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
 # include <boost/preprocessor/facilities/overload.hpp>
 # include <boost/preprocessor/tuple/size.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 #
 # /* BOOST_PP_TUPLE_REVERSE */
 #
@ -31,7 +33,12 @@
 #        define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
 #    else
 #        define BOOST_PP_TUPLE_REVERSE(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_REVERSE_O_, __VA_ARGS__)(__VA_ARGS__)
-#        define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        if BOOST_PP_VARIADIC_HAS_OPT()
+#            define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_TUPLE_REVERSE_O_1_SIZE(BOOST_PP_VARIADIC_SIZE tuple,tuple)
+#            define BOOST_PP_TUPLE_REVERSE_O_1_SIZE(size,tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_IF(size,size,1)) tuple
+#        else
+#            define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        endif
 #    endif
 #    define BOOST_PP_TUPLE_REVERSE_O_2(size, tuple) BOOST_PP_TUPLE_REVERSE_O_1(tuple)
 # else
--- a/include/boost/preprocessor/tuple/size.hpp
+++ b/include/boost/preprocessor/tuple/size.hpp
@ -15,10 +15,19 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
 #
 # if BOOST_PP_VARIADICS
-#    if BOOST_PP_VARIADICS_MSVC
+#    if BOOST_PP_VARIADIC_HAS_OPT()
+#        if BOOST_PP_VARIADICS_MSVC
+#            define BOOST_PP_TUPLE_SIZE(tuple) BOOST_PP_TUPLE_SIZE_CHECK(BOOST_PP_CAT(BOOST_PP_VARIADIC_SIZE tuple,))
+#        else
+#            define BOOST_PP_TUPLE_SIZE(tuple) BOOST_PP_TUPLE_SIZE_CHECK(BOOST_PP_VARIADIC_SIZE tuple)
+#        endif
+#        define BOOST_PP_TUPLE_SIZE_CHECK(size) BOOST_PP_IF(size,size,1)
+#    elif BOOST_PP_VARIADICS_MSVC
 #        define BOOST_PP_TUPLE_SIZE(tuple) BOOST_PP_CAT(BOOST_PP_VARIADIC_SIZE tuple,)
 #    else
 #        define BOOST_PP_TUPLE_SIZE(tuple) BOOST_PP_VARIADIC_SIZE tuple
--- a/include/boost/preprocessor/tuple/to_array.hpp
+++ b/include/boost/preprocessor/tuple/to_array.hpp
@ -15,9 +15,11 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
 # include <boost/preprocessor/facilities/overload.hpp>
 # include <boost/preprocessor/tuple/size.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 #
 # /* BOOST_PP_TUPLE_TO_ARRAY */
 #
@ -29,7 +31,12 @@
 #        define BOOST_PP_TUPLE_TO_ARRAY_1(tuple) (BOOST_PP_TUPLE_SIZE(tuple), tuple)
 #    else
 #        define BOOST_PP_TUPLE_TO_ARRAY(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_TO_ARRAY_, __VA_ARGS__)(__VA_ARGS__)
-#        define BOOST_PP_TUPLE_TO_ARRAY_1(tuple) (BOOST_PP_VARIADIC_SIZE tuple, tuple)
+#        if BOOST_PP_VARIADIC_HAS_OPT()
+#            define BOOST_PP_TUPLE_TO_ARRAY_1(tuple) BOOST_PP_TUPLE_TO_ARRAY_1_SIZE(BOOST_PP_VARIADIC_SIZE tuple, tuple)
+#            define BOOST_PP_TUPLE_TO_ARRAY_1_SIZE(size,tuple) (BOOST_PP_IF(size,size,1), tuple)
+#        else
+#            define BOOST_PP_TUPLE_TO_ARRAY_1(tuple) (BOOST_PP_VARIADIC_SIZE tuple, tuple)
+#        endif
 #    endif
 #    define BOOST_PP_TUPLE_TO_ARRAY_2(size, tuple) (size, tuple)
 # else
--- a/include/boost/preprocessor/tuple/to_list.hpp
+++ b/include/boost/preprocessor/tuple/to_list.hpp
@ -17,9 +17,11 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
 # include <boost/preprocessor/facilities/overload.hpp>
 # include <boost/preprocessor/tuple/size.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 #
 # /* BOOST_PP_TUPLE_TO_LIST */
 #
@ -31,7 +33,12 @@
 #        define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
 #    else
 #        define BOOST_PP_TUPLE_TO_LIST(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_TO_LIST_O_, __VA_ARGS__)(__VA_ARGS__)
-#        define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        if BOOST_PP_VARIADIC_HAS_OPT()
+#            define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_TUPLE_TO_LIST_O_1_SIZE(BOOST_PP_VARIADIC_SIZE tuple, tuple)
+#            define BOOST_PP_TUPLE_TO_LIST_O_1_SIZE(size,tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_IF(size,size,1)) tuple
+#        else
+#            define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        endif
 #    endif
 #    define BOOST_PP_TUPLE_TO_LIST_O_2(size, tuple) BOOST_PP_TUPLE_TO_LIST_O_1(tuple)
 # else
--- a/include/boost/preprocessor/tuple/to_seq.hpp
+++ b/include/boost/preprocessor/tuple/to_seq.hpp
@ -15,9 +15,11 @@
 #
 # include <boost/preprocessor/cat.hpp>
 # include <boost/preprocessor/config/config.hpp>
+# include <boost/preprocessor/control/if.hpp>
 # include <boost/preprocessor/facilities/overload.hpp>
 # include <boost/preprocessor/tuple/size.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 #
 # /* BOOST_PP_TUPLE_TO_SEQ */
 #
@ -29,7 +31,12 @@
 #        define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
 #    else
 #        define BOOST_PP_TUPLE_TO_SEQ(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_TO_SEQ_O_, __VA_ARGS__)(__VA_ARGS__)
-#        define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        if BOOST_PP_VARIADIC_HAS_OPT()
+#            define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_TUPLE_TO_SEQ_O_1_SIZE(BOOST_PP_VARIADIC_SIZE tuple, tuple)
+#            define BOOST_PP_TUPLE_TO_SEQ_O_1_SIZE(size,tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_IF(size,size,1)) tuple
+#        else
+#            define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        endif
 #    endif
 #    define BOOST_PP_TUPLE_TO_SEQ_O_2(size, tuple) BOOST_PP_TUPLE_TO_SEQ_O_1(tuple)
 # else