1 files changed, 29 insertions, 0 deletions
diff --git a/src/stdlib/mapmacro.h b/src/stdlib/mapmacro.h
new file mode 100644
index 00000000..5ed7a4b7
--- /dev/null
+++ b/src/stdlib/mapmacro.h
@@ -0,0 +1,29 @@
+#pragma once
+
+// This file defines a MAP_LIST(fn, ...) function that applies a function to
+// every one of the varargs.
+// For example: baz(MAP_LIST(foo, 1, "x")) -> baz(foo(1), foo("x"))
+
+#define EVAL0(...) __VA_ARGS__
+#define EVAL1(...) EVAL0(EVAL0(EVAL0(__VA_ARGS__)))
+#define EVAL2(...) EVAL1(EVAL1(EVAL1(__VA_ARGS__)))
+#define EVAL3(...) EVAL2(EVAL2(EVAL2(__VA_ARGS__)))
+#define EVAL4(...) EVAL3(EVAL3(EVAL3(__VA_ARGS__)))
+#define EVAL(...)  EVAL4(EVAL4(EVAL4(__VA_ARGS__)))
+
+#define MAP_END(...)
+#define MAP_OUT
+#define MAP_COMMA ,
+
+#define MAP_GET_END2() 0, MAP_END
+#define MAP_GET_END1(...) MAP_GET_END2
+#define MAP_GET_END(...) MAP_GET_END1
+#define MAP_NEXT0(test, next, ...) next MAP_OUT
+
+#define MAP_LIST_NEXT1(test, next) MAP_NEXT0(test, MAP_COMMA next, 0)
+#define MAP_LIST_NEXT(test, next)  MAP_LIST_NEXT1(MAP_GET_END test, next)
+
+#define MAP_LIST0(f, x, peek, ...) f(x) MAP_LIST_NEXT(peek, MAP_LIST1)(f, peek, __VA_ARGS__)
+#define MAP_LIST1(f, x, peek, ...) f(x) MAP_LIST_NEXT(peek, MAP_LIST0)(f, peek, __VA_ARGS__)
+
+#define MAP_LIST(f, ...) EVAL(MAP_LIST1(f, __VA_ARGS__, ()()(), ()()(), ()()(), 0))