match expression in c

main.c

void main() {
    char* first =
        match(char *, 1) {
            when(1):
                return "Drake";
            when(2):
                return "Charles";
            otherwise:
                return "";
            end
        }

    char *last =
        match (char *, first) {
            when("Drake"):
                return "Lucas";
            otherwise:
                return "Don't know";
            end
        }

    printf("%s %s", first, last);
}

match.h

#ifndef __MATCH__
#define __MATCH__

#include <stdio.h>
#include <string.h>

#define match_concat(x,y) x##y

#define match(type,x) \
    ({ \
        __auto_type value = x; \
        int _eq(typeof (x) a, typeof (x) b) { \
            return a == b; \
        } \
        int _streq(const char* a, const char* b) { \
            return strcmp (a,b) == 0; \
        } \
        type _match(typeof (x) value) { \
            if (0)

#define _when(x, idx) \
            } \
            if (_Generic(x, char *: _streq, const char *: _streq, default: _eq)(value,x)) { \
                goto match_concat(match_label_, idx); \
            } \
            if (0) { \
                match_concat(match_label_, idx)

#define _otherwise(idx) \
    } \
    goto match_concat(match_label_, idex); \
    if (0) { \
        match_concat(match_label_, idex)

#define end \
            } \
        } \
        _match(value); \
    }); {


#define when(x) _when(x, __COUNTER__)
#define otherwise _otherwise(__COUNTER__)

#endif