split.c

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

/*
 - split - divide a string into fields, like awk split()
 = int split(char *string, char *fields[], int nfields, char *sep);
 */
int				/* number of fields, including overflow */
split(string, fields, nfields, sep)
char *string;
char *fields[];			/* list is not NULL-terminated */
int nfields;			/* number of entries available in fields[] */
char *sep;			/* "" white, "c" single char, "ab" [ab]+ */
{
	char *p = string;
	char c;			/* latest character */
	char sepc = sep[0];
	char sepc2;
	int fn;
	char **fp = fields;
	char *sepp;
	int trimtrail;

	/* white space */
	if (sepc == '\0') {
		while ((c = *p++) == ' ' || c == '\t')
			continue;
		p--;
		trimtrail = 1;
		sep = " \t";	/* note, code below knows this is 2 long */
		sepc = ' ';
	} else
		trimtrail = 0;
	sepc2 = sep[1];		/* now we can safely pick this up */

	/* catch empties */
	if (*p == '\0')
		return(0);

	/* single separator */
	if (sepc2 == '\0') {
		fn = nfields;
		for (;;) {
			*fp++ = p;
			fn--;
			if (fn == 0)
				break;
			while ((c = *p++) != sepc)
				if (c == '\0')
					return(nfields - fn);
			*(p-1) = '\0';
		}
		/* we have overflowed the fields vector -- just count them */
		fn = nfields;
		for (;;) {
			while ((c = *p++) != sepc)
				if (c == '\0')
					return(fn);
			fn++;
		}
		/* not reached */
	}

	/* two separators */
	if (sep[2] == '\0') {
		fn = nfields;
		for (;;) {
			*fp++ = p;
			fn--;
			while ((c = *p++) != sepc && c != sepc2)
				if (c == '\0') {
					if (trimtrail && **(fp-1) == '\0')
						fn++;
					return(nfields - fn);
				}
			if (fn == 0)
				break;
			*(p-1) = '\0';
			while ((c = *p++) == sepc || c == sepc2)
				continue;
			p--;
		}
		/* we have overflowed the fields vector -- just count them */
		fn = nfields;
		while (c != '\0') {
			while ((c = *p++) == sepc || c == sepc2)
				continue;
			p--;
			fn++;
			while ((c = *p++) != '\0' && c != sepc && c != sepc2)
				continue;
		}
		/* might have to trim trailing white space */
		if (trimtrail) {
			p--;
			while ((c = *--p) == sepc || c == sepc2)
				continue;
			p++;
			if (*p != '\0') {
				if (fn == nfields+1)
					*p = '\0';
				fn--;
			}
		}
		return(fn);
	}

	/* n separators */
	fn = 0;
	for (;;) {
		if (fn < nfields)
			*fp++ = p;
		fn++;
		for (;;) {
			c = *p++;
			if (c == '\0')
				return(fn);
			sepp = sep;
			while ((sepc = *sepp++) != '\0' && sepc != c)
				continue;
			if (sepc != '\0')	/* it was a separator */
				break;
		}
		if (fn < nfields)
			*(p-1) = '\0';
		for (;;) {
			c = *p++;
			sepp = sep;
			while ((sepc = *sepp++) != '\0' && sepc != c)
				continue;
			if (sepc == '\0')	/* it wasn't a separator */
				break;
		}
		p--;
	}

	/* not reached */
}

#ifdef TEST_SPLIT


/*
 * test program
 * pgm		runs regression
 * pgm sep	splits stdin lines by sep
 * pgm str sep	splits str by sep
 * pgm str sep n	splits str by sep n times
 */
int
main(argc, argv)
int argc;
char *argv[];
{
	char buf[512];
	int n;
#	define	MNF	10
	char *fields[MNF];

	if (argc > 4)
		for (n = atoi(argv[3]); n > 0; n--) {
			(void) strcpy(buf, argv[1]);
		}
	else if (argc > 3)
		for (n = atoi(argv[3]); n > 0; n--) {
			(void) strcpy(buf, argv[1]);
			(void) split(buf, fields, MNF, argv[2]);
		}
	else if (argc > 2)
		dosplit(argv[1], argv[2]);
	else if (argc > 1)
		while (fgets(buf, sizeof(buf), stdin) != NULL) {
			buf[strlen(buf)-1] = '\0';	/* stomp newline */
			dosplit(buf, argv[1]);
		}
	else
		regress();

	exit(0);
}

static void
dosplit(string, seps)
char *string;
char *seps;
{
#	define	NF	5
	char *fields[NF];
	int nf;

	nf = split(string, fields, NF, seps);
	print(nf, NF, fields);
}

static void
print(nf, nfp, fields)
int nf;
int nfp;
char *fields[];
{
	int fn;
	int bound;

	bound = (nf > nfp) ? nfp : nf;
	printf("%d:\t", nf);
	for (fn = 0; fn < bound; fn++)
		printf("\"%s\"%s", fields[fn], (fn+1 < nf) ? ", " : "\n");
}

#define	RNF	5		/* some table entries know this */
struct {
	char *str;
	char *seps;
	int nf;
	char *fi[RNF];
} tests[] = {
	"",		" ",	0,	{ "" },
	" ",		" ",	2,	{ "", "" },
	"x",		" ",	1,	{ "x" },
	"xy",		" ",	1,	{ "xy" },
	"x y",		" ",	2,	{ "x", "y" },
	"abc def  g ",	" ",	5,	{ "abc", "def", "", "g", "" },
	"  a bcd",	" ",	4,	{ "", "", "a", "bcd" },
	"a b c d e f",	" ",	6,	{ "a", "b", "c", "d", "e f" },
	" a b c d ",	" ",	6,	{ "", "a", "b", "c", "d " },

	"",		" _",	0,	{ "" },
	" ",		" _",	2,	{ "", "" },
	"x",		" _",	1,	{ "x" },
	"x y",		" _",	2,	{ "x", "y" },
	"ab _ cd",	" _",	2,	{ "ab", "cd" },
	" a_b  c ",	" _",	5,	{ "", "a", "b", "c", "" },
	"a b c_d e f",	" _",	6,	{ "a", "b", "c", "d", "e f" },
	" a b c d ",	" _",	6,	{ "", "a", "b", "c", "d " },

	"",		" _~",	0,	{ "" },
	" ",		" _~",	2,	{ "", "" },
	"x",		" _~",	1,	{ "x" },
	"x y",		" _~",	2,	{ "x", "y" },
	"ab _~ cd",	" _~",	2,	{ "ab", "cd" },
	" a_b  c~",	" _~",	5,	{ "", "a", "b", "c", "" },
	"a b_c d~e f",	" _~",	6,	{ "a", "b", "c", "d", "e f" },
	"~a b c d ",	" _~",	6,	{ "", "a", "b", "c", "d " },

	"",		" _~-",	0,	{ "" },
	" ",		" _~-",	2,	{ "", "" },
	"x",		" _~-",	1,	{ "x" },
	"x y",		" _~-",	2,	{ "x", "y" },
	"ab _~- cd",	" _~-",	2,	{ "ab", "cd" },
	" a_b  c~",	" _~-",	5,	{ "", "a", "b", "c", "" },
	"a b_c-d~e f",	" _~-",	6,	{ "a", "b", "c", "d", "e f" },
	"~a-b c d ",	" _~-",	6,	{ "", "a", "b", "c", "d " },

	"",		"  ",	0,	{ "" },
	" ",		"  ",	2,	{ "", "" },
	"x",		"  ",	1,	{ "x" },
	"xy",		"  ",	1,	{ "xy" },
	"x y",		"  ",	2,	{ "x", "y" },
	"abc def  g ",	"  ",	4,	{ "abc", "def", "g", "" },
	"  a bcd",	"  ",	3,	{ "", "a", "bcd" },
	"a b c d e f",	"  ",	6,	{ "a", "b", "c", "d", "e f" },
	" a b c d ",	"  ",	6,	{ "", "a", "b", "c", "d " },

	"",		"",	0,	{ "" },
	" ",		"",	0,	{ "" },
	"x",		"",	1,	{ "x" },
	"xy",		"",	1,	{ "xy" },
	"x y",		"",	2,	{ "x", "y" },
	"abc def  g ",	"",	3,	{ "abc", "def", "g" },
	"\t a bcd",	"",	2,	{ "a", "bcd" },
	"  a \tb\t c ",	"",	3,	{ "a", "b", "c" },
	"a b c d e ",	"",	5,	{ "a", "b", "c", "d", "e" },
	"a b\tc d e f",	"",	6,	{ "a", "b", "c", "d", "e f" },
	" a b c d e f ",	"",	6,	{ "a", "b", "c", "d", "e f " },

	NULL,		NULL,	0,	{ NULL },
};

static void
regress()
{
	char buf[512];
	int n;
	char *fields[RNF+1];
	int nf;
	int i;
	int printit;
	char *f;

	for (n = 0; tests[n].str != NULL; n++) {
		(void) strcpy(buf, tests[n].str);
		fields[RNF] = NULL;
		nf = split(buf, fields, RNF, tests[n].seps);
		printit = 0;
		if (nf != tests[n].nf) {
			printf("split `%s' by `%s' gave %d fields, not %d\n",
				tests[n].str, tests[n].seps, nf, tests[n].nf);
			printit = 1;
		} else if (fields[RNF] != NULL) {
			printf("split() went beyond array end\n");
			printit = 1;
		} else {
			for (i = 0; i < nf && i < RNF; i++) {
				f = fields[i];
				if (f == NULL)
					f = "(NULL)";
				if (strcmp(f, tests[n].fi[i]) != 0) {
					printf("split `%s' by `%s', field %d is `%s', not `%s'\n",
						tests[n].str, tests[n].seps,
						i, fields[i], tests[n].fi[i]);
					printit = 1;
				}
			}
		}
		if (printit)
			print(nf, RNF, fields);
	}
}
#endif