macro-args-iter.h

#define STRINGIZE(arg) STRINGIZE1(arg)
#define STRINGIZE1(arg) STRINGIZE2(arg)
#define STRINGIZE2(arg) #arg

#define CONCATENATE(arg1, arg2) CONCATENATE1(arg1, arg2)
#define CONCATENATE1(arg1, arg2) CONCATENATE2(arg1, arg2)
#define CONCATENATE2(arg1, arg2) arg1##arg2

#define FOR_EACH_1(what, ...) what(__VA_ARGS__);
#define FOR_EACH_2(what, x, ...) \
  what(x);                       \
  FOR_EACH_1(what, __VA_ARGS__);
#define FOR_EACH_3(what, x, ...) \
  what(x);                       \
  FOR_EACH_2(what, __VA_ARGS__);
#define FOR_EACH_4(what, x, ...) \
  what(x);                       \
  FOR_EACH_3(what, __VA_ARGS__);
#define FOR_EACH_5(what, x, ...) \
  what(x);                       \
  FOR_EACH_4(what, __VA_ARGS__);
#define FOR_EACH_6(what, x, ...) \
  what(x);                       \
  FOR_EACH_5(what, __VA_ARGS__);
#define FOR_EACH_7(what, x, ...) \
  what(x);                       \
  FOR_EACH_6(what, __VA_ARGS__);
#define FOR_EACH_8(what, x, ...) \
  what(x);                       \
  FOR_EACH_7(what, __VA_ARGS__);
#define FOR_EACH_9(what, x, ...) \
  what(x);                       \
  FOR_EACH_8(what, __VA_ARGS__);
#define FOR_EACH_10(what, x, ...) \
  what(x);                        \
  FOR_EACH_9(what, __VA_ARGS__);
#define FOR_EACH_11(what, x, ...) \
  what(x);                        \
  FOR_EACH_10(what, __VA_ARGS__);
#define FOR_EACH_12(what, x, ...) \
  what(x);                        \
  FOR_EACH_11(what, __VA_ARGS__);
#define FOR_EACH_13(what, x, ...) \
  what(x);                        \
  FOR_EACH_12(what, __VA_ARGS__);
#define FOR_EACH_14(what, x, ...) \
  what(x);                        \
  FOR_EACH_13(what, __VA_ARGS__);
#define FOR_EACH_15(what, x, ...) \
  what(x);                        \
  FOR_EACH_14(what, __VA_ARGS__);
#define FOR_EACH_16(what, x, ...) \
  what(x);                        \
  FOR_EACH_15(what, __VA_ARGS__);

#define FOR_EACH_NARG(...) FOR_EACH_NARG_(__VA_ARGS__, FOR_EACH_RSEQ_N())
#define FOR_EACH_NARG_(...) FOR_EACH_ARG_N(__VA_ARGS__)
#define FOR_EACH_ARG_N(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, \
                       _14, _15, _16, N, ...)                                  \
  N
#define FOR_EACH_RSEQ_N() \
  16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0

#define FOR_EACH_(N, what, ...) CONCATENATE(FOR_EACH_, N)(what, __VA_ARGS__)
#define FOR_EACH(what, ...) \
  FOR_EACH_(FOR_EACH_NARG(__VA_ARGS__), what, __VA_ARGS__)