enumstr.c

// [src] https://www.scs.stanford.edu/~dm/blog/va-opt.html
//
// gcc enum.c
// clang enum.c
// cl enum.c /Zc:preprocessor

#define PARENS ()

// Rescan macro tokens 256 times
#define EXPAND(arg) EXPAND1(EXPAND1(EXPAND1(EXPAND1(arg))))
#define EXPAND1(arg) EXPAND2(EXPAND2(EXPAND2(EXPAND2(arg))))
#define EXPAND2(arg) EXPAND3(EXPAND3(EXPAND3(EXPAND3(arg))))
#define EXPAND3(arg) EXPAND4(EXPAND4(EXPAND4(EXPAND4(arg))))
#define EXPAND4(arg) arg

#define FOR_EACH(macro, ...)                                    \
    __VA_OPT__(EXPAND(FOR_EACH_HELPER(macro, __VA_ARGS__)))
#define FOR_EACH_HELPER(macro, a1, ...)                         \
    macro(a1)                                                     \
    __VA_OPT__(FOR_EACH_AGAIN PARENS (macro, __VA_ARGS__))
#define FOR_EACH_AGAIN() FOR_EACH_HELPER

#define ENUM_CASE(name) case name: return #name;

#define MAKE_ENUM(type, typestr, ...)        \
typedef enum type { __VA_ARGS__ } type;      \
const char *typestr(type _e) {               \
    switch (_e) { default: return "";        \
    FOR_EACH(ENUM_CASE, __VA_ARGS__) }}

MAKE_ENUM(MyType, MyTypeStr, ZERO, ONE, TWO, THREE);

#include <stdio.h>

void test(MyType e) {
    printf("%s=%d\n", MyTypeStr(e), e);
}

int main() {
    test(ZERO);
    test(ONE);
    test(TWO);
    test(THREE);
}

/*
ZERO=0
ONE=1
TWO=2
THREE=3
*/