Better concat that doesn't need a size argument

1 files changed, 21 insertions, 1 deletions

diff --git a/src/util.h b/src/util.h
index 64b39e3..278d809 100644
--- a/src/util.h
+++ b/src/util.h
@@ -17,10 +17,30 @@ extern void __attribute__((noreturn)) die_(const char *err, ...);
 extern void *xmalloc(size_t size);
 extern void *xrealloc(void *ptr, size_t size);
 extern char *xstrdup(const char *str);
-extern char *concat(size_t count, ...);
 extern unsigned char *hash_file(FILE *fp);
 extern void sha1_to_hex(const unsigned char *sha1, char *buf);
 extern void hex_to_sha1(const char *s, unsigned char *sha1);
 extern uint32_t generate_seed();
 
+/* crazy macros for returning the number of arguments in __VA_ARGS__ */
+/* See https://stackoverflow.com/questions/2308243/ */
+#define PP_NARG(...) __PP_NARG(__VA_ARGS__, __PP_RSEQ_N())
+#define __PP_NARG(...) __PP_ARG_N(__VA_ARGS__)
+#define __PP_ARG_N(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13,     \
+                   _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, \
+                   _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, \
+                   _38, _39, _40, _41, _42, _43, _44, _45, _46, _47, _48, _49, \
+                   _50, _51, _52, _53, _54, _55, _56, _57, _58, _59, _60, _61, \
+                   _62, _63, N, ...) N
+
+#define __PP_RSEQ_N()                                                          \
+	63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47,    \
+	        46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32,    \
+	        31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17,    \
+	        16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0
+
+#define concat(...) concat_(PP_NARG(__VA_ARGS__), __VA_ARGS__)
+
+extern char *concat_(size_t count, ...);
+
 #endif