P99_ALLBUTLAST P99_CHS P99_DUPL P99_HAS_COMMA P99_IS_EMPTY P99_LAST P99_NARG P99_SELS P99_SKP P99_SUB

P99_IS_EMPTY #define P99_IS_EMPTY (   ... ) Value: P00_ISEMPTY( \ /* test if there is just one argument, that might be empty */ \ P99_HAS_COMMA(__VA_ARGS__), \ /* test if P99_IS__EQ__ together with the argument \ adds a comma */ \ P99_HAS_COMMA(P00_IS__EQ__ __VA_ARGS__), \ /* test if the argument together with a parenthesis \ adds a comma */ \ P99_HAS_COMMA(__VA_ARGS__ (/*empty*/)), \ /* test if placing it between P99_IS__EQ__ and the \ parenthesis adds a comma */ \ P99_HAS_COMMA(P00_IS__EQ__ __VA_ARGS__ (/*empty*/)) \ ) Test if the argument list is empty. This expands to token 1 if the list was empty and to token 0 if there was anything other than a comment in the list. The implementation of this macro is kind of tricky and relies heavily on the fact that a function macro (P00_IS__EQ__ in this case) is left untouched if it is not followed by a parenthesis. See http://gustedt.wordpress.com/2010/06/08/detect-empty-macro-arguments/ Returns tokens 0 or 1 Warning This macro should work for most reasonable invocations (balanced parenthesis and stuff like that). The only case that definitely does not work is when called with another macro X at the end of its argument list, where X itself expects more than one argument. The particular cases where X receives 0, 1 or a variable number of arguments should be fine. Definition at line 75 of file p99_args.h.