FOR_EACH macro with two or more params in call macro

Question

Here is some C++ macro code that simulates for-loops to eliminate copy and pasted code.

#define SEMICOLON ;
#define LOL(x) print(x)
#define LOLZ(...) FOR_EACH(LOL, SEMICOLON, ##__VA_ARGS__)

LOLZ("hi", "my", "friend", "!");

// result
print("hi"); print("my"); print("friend"); print("!");

And also I can show the code to create this macros (I found this here on Stack Overflow):

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

#define FOR_EACH_NARG(...) FOR_EACH_NARG_(__VA_ARGS__, FOR_EACH_RSEQ_N())
#define FOR_EACH_NARG_(...) EXPAND(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 CONCATENATE(x,y) x##y
#define FOR_EACH_(N, what, delimiter, ...) EXPAND(CONCATENATE(FOR_EACH_, N)(what, delimiter, __VA_ARGS__))


#define FOR_EACH(what, delimiter, ...) FOR_EACH_(FOR_EACH_NARG(__VA_ARGS__), what, delimiter, __VA_ARGS__)

But I have difficulty with two arguments for the function: I need use func(x, y) at one iteration of this macro. Calling macro must be looks like:

MY_DUAL_FOREACH_LIKE_MACRO(
  x1, y1,
  x2, y2,
  x3, y3
)

// and I expect to get:
func(x1, y1); func(x2, y2); func(x3, y3);

If I add "y" near the "x" argument at macro I will got x2 unsed substitutions of calling "what" argument:

func(x1, y1); func(x2, y2); func(x3, y3); func(, ); func(, ); func(, );

If you have experience in this, please help me recode this macro to dual arguments type FOR_EACH macro.

FOR_EACH macro with two or more params in call macro

3 Answers