ragel_test.rl

#include <assert.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>

static const uint64_t ERROR = ~0lu;

struct match {
	size_t so, eo;
};

#define YYMAXNMATCH 32

%%{
	machine foo;

	action A {
		matches[nmatches++].so = p-start;
	}

	action E {
		for(int i = nmatches-1; i>=0; --i) if(!defined[i]) {
			matches[i].eo = p-start;
			defined[i] = 1;
			break;
		}
	}


	main := [ \t]*[ \t]+(((((([0-9]{1,3}) >A %E [.]){3} >A %E [0-9]{1,3}) >A %E ([/][0-9]+){0,1} >A %E ) >A %E |(((([0-9a-f:]{2,39}) >A %E ) >A %E |(([0-9a-f:]{0,29}[:]((([0-9]{1,3}) >A %E [.]){3} >A %E [0-9]{1,3}) >A %E ) >A %E ) >A %E ) >A %E ([/][0-9]+){0,1} >A %E ) >A %E ) >A %E |([a-z0-9._]+) >A %E ) >A %E [ \t\n]* ;

}%%

static int lex(const char *p, struct match matches[])
{
	const char *start = p, *pe = p + strlen(p), *eof = pe;
	size_t cs;
	char defined[YYMAXNMATCH] = {0};
	size_t nmatches = 0;
	%% write data;
	%% write init;
	%% write exec;
	if(cs < %%{ write first_final; }%% ) return -1;
	else return nmatches;
}

char* display_match(const char* s, struct match matches[], int mno) {
	static char buf[1024];
	snprintf(buf, sizeof buf, "%.*s", (int)(matches[mno].eo - matches[mno].so), s+matches[mno].so);
	return buf;
}


#include <regex.h>
int main()
{
	struct match matches[YYMAXNMATCH];
	const char *expr = " 127.0.0.1/24";
	int mno = lex(expr, matches);
	if(mno == -1) {
		fprintf(stderr, "fail\n");
		return 1;
	} else {
		printf("n matches: %d\n", mno);
		for(int i=0; i< mno; ++i)
			printf("%s\n", display_match(expr, matches, i));
	}

	return mno;
}