mapmacro.h - tomo

(27 lines)
   1 // This file defines a MAP_LIST(fn, ...) function that applies a function to
   2 // every one of the varargs.
   3 // For example: baz(MAP_LIST(foo, 1, "x")) -> baz(foo(1), foo("x"))
   4 
   5 #pragma once
   6 
   7 #define EVAL0(...) __VA_ARGS__
   8 #define EVAL1(...) EVAL0(EVAL0(EVAL0(__VA_ARGS__)))
   9 #define EVAL2(...) EVAL1(EVAL1(EVAL1(__VA_ARGS__)))
  10 #define EVAL(...) EVAL2(EVAL2(EVAL2(__VA_ARGS__)))
  11 
  12 #define MAP_END(...)
  13 #define MAP_OUT
  14 #define MAP_COMMA ,
  15 
  16 #define MAP_GET_END2() 0, MAP_END
  17 #define MAP_GET_END1(...) MAP_GET_END2
  18 #define MAP_GET_END(...) MAP_GET_END1
  19 #define MAP_NEXT0(test, next, ...) next MAP_OUT
  20 
  21 #define MAP_LIST_NEXT1(test, next) MAP_NEXT0(test, MAP_COMMA next, 0)
  22 #define MAP_LIST_NEXT(test, next) MAP_LIST_NEXT1(MAP_GET_END test, next)
  23 
  24 #define MAP_LIST0(f, x, peek, ...) f(x) MAP_LIST_NEXT(peek, MAP_LIST1)(f, peek, __VA_ARGS__)
  25 #define MAP_LIST1(f, x, peek, ...) f(x) MAP_LIST_NEXT(peek, MAP_LIST0)(f, peek, __VA_ARGS__)
  26 
  27 #define MAP_LIST(f, ...) EVAL(MAP_LIST1(f, __VA_ARGS__, ()()(), ()()(), ()()(), 0))