ranged designated initializers in c99

main.c

#include <stdio.h>

#define E2(...) E1(E1(E1(E1(E1(E1(E1(E1(E1(E1(__VA_ARGS__))))))))))
#define E1(...) __VA_ARGS__
#define EMPTY()
#define DEFER1(m) m EMPTY()

#define APPLY3(F,a,x,y,v) F(a,0,x,y,v), F(a,1,x,y,v), F(a,2,x,y,v), \
                          F(a,3,x,y,v), F(a,4,x,y,v), F(a,5,x,y,v), \
                          F(a,6,x,y,v), F(a,7,x,y,v), F(a,8,x,y,v), \
                          F(a,9,x,y,v)
#define APPLY3_() APPLY3

#define F(a,b,x,y,v)     [(a*10+b)>=x && (a*10+b)<=y?(a*10+b):0]=v
#define F10(a,b,x,y,v)   DEFER1(APPLY3_)()(F, a*100+b, x, y, v)
#define F100(a,b,x,y,v)   DEFER1(APPLY3_)()(F10, a*1000+b, x, y, v)
#define F1000(a,b,x,y,v)   DEFER1(APPLY3_)()(F100, a*10000+b, x, y, v)
#define F10000(a,b,x,y,v)   DEFER1(APPLY3_)()(F1000, a*100000+b, x, y, v)
#define F100000(a,b,x,y,v)   DEFER1(APPLY3_)()(F10000, a*1000000+b, x, y, v)
#define F1000000(a,b,x,y,v)   DEFER1(APPLY3_)()(F100000, b, x, y, v)

#define RANGE(min,max,val) E2(DEFER1(APPLY3_)()(F100, 0, min, max, val))


int tbl[] = {
	RANGE('a', 'z', 42),
	RANGE('A', 'Z', 42),
	RANGE('0', '9', 42),
	[0] = 0; /* make sure to set [0], because it's overwritten by RANGE */ 
};

int
main(void)
{
	for (int i = 0; i < 256; ++i)
		if (tbl[i] == 42)
			putchar(i);
	putchar('\n');
}