Implement CPPMAGIC_IFELSE which operates similar to the C ? : operator, but is evaluated at preprocessing time.
Signed-off-by: David Gibson <[email protected]> --- ccan/cppmagic/cppmagic.h | 14 ++++++++++++++ ccan/cppmagic/test/run.c | 6 +++++- 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/ccan/cppmagic/cppmagic.h b/ccan/cppmagic/cppmagic.h index c4454e7..b5c3578 100644 --- a/ccan/cppmagic/cppmagic.h +++ b/ccan/cppmagic/cppmagic.h @@ -84,4 +84,18 @@ #define CPPMAGIC_ISEMPTY(...) \ CPPMAGIC_ISZERO(CPPMAGIC_NONEMPTY(__VA_ARGS__)) +/* + * CPPMAGIC_IFELSE - preprocessor conditional + * + * CPPMAGIC_IFELSE(@cond)(@if)(@else) + * expands to @else if @cond is '0', otherwise expands to @if + */ +#define _CPPMAGIC_IF_0(...) _CPPMAGIC_IF_0_ELSE +#define _CPPMAGIC_IF_1(...) __VA_ARGS__ _CPPMAGIC_IF_1_ELSE +#define _CPPMAGIC_IF_0_ELSE(...) __VA_ARGS__ +#define _CPPMAGIC_IF_1_ELSE(...) +#define _CPPMAGIC_IFELSE(cond_) CPPMAGIC_GLUE2(_CPPMAGIC_IF_, cond_) +#define CPPMAGIC_IFELSE(cond_) \ + _CPPMAGIC_IFELSE(CPPMAGIC_NONZERO(cond_)) + #endif /* CCAN_CPPMAGIC_H */ diff --git a/ccan/cppmagic/test/run.c b/ccan/cppmagic/test/run.c index fb2bfb9..0f8917d 100644 --- a/ccan/cppmagic/test/run.c +++ b/ccan/cppmagic/test/run.c @@ -17,7 +17,7 @@ static inline void check1(const char *orig, const char *expand, int main(void) { - plan_tests(21); + plan_tests(24); CHECK1(CPPMAGIC_NOTHING(), ""); CHECK1(CPPMAGIC_GLUE2(a, b), "ab"); @@ -47,6 +47,10 @@ int main(void) CHECK1(CPPMAGIC_ISEMPTY(0), "0"); CHECK1(CPPMAGIC_ISEMPTY(a, b, c), "0"); + CHECK1(CPPMAGIC_IFELSE(0)(abc)(def), "def"); + CHECK1(CPPMAGIC_IFELSE(1)(abc)(def), "abc"); + CHECK1(CPPMAGIC_IFELSE(not zero)(abc)(def), "abc"); + /* This exits depending on whether all tests passed */ return exit_status(); } -- 2.5.0 _______________________________________________ ccan mailing list [email protected] https://lists.ozlabs.org/listinfo/ccan
