/* lib_stringmatch.c - stolen from Tcl.  Thanks, John. */
/* Author: John Ousterhout, ouster@sprite.berkeley.edu */
/*
 *----------------------------------------------------------------------
 *
 * exp_stringmatch --
 *
 *	See if a particular string matches a particular pattern.
 *
 * Results:
 *	The return value is 1 if string matches pattern, and
 *	0 otherwise.  The matching operation permits the following
 *	special characters in the pattern: *?\[] (see the manual
 *	entry for details on what these mean).
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
exp_stringmatch(string, pattern)
    register char *string;	/* String. */
    register char *pattern;	/* Pattern, which may contain
				 * special characters. */
{
    char c2;

    while (1) {
	/* See if we're at the end of both the pattern and the string.
	 * If so, we succeeded.  If we're at the end of the pattern
	 * but not at the end of the string, we failed.
	 */
	
	if (*pattern == 0) {
	    if (*string == 0) {
		return 1;
	    } else {
		return 0;
	    }
	}
	if ((*string == 0) && (*pattern != '*')) {
	    return 0;
	}

	/* Check for a "*" as the next pattern character.  It matches
	 * any substring.  We handle this by calling ourselves
	 * recursively for each postfix of string, until either we
	 * match or we reach the end of the string.
	 */
	
	if (*pattern == '*') {
	    pattern += 1;
	    if (*pattern == 0) {
		return 1;
	    }
	    while (*string != 0) {
		if (exp_stringmatch(string, pattern)) {
		    return 1;
		}
		string += 1;
	    }
	    return 0;
	}
    
	/* Check for a "?" as the next pattern character.  It matches
	 * any single character.
	 */

	if (*pattern == '?') {
	    goto thisCharOK;
	}

	/* Check for a "[" as the next pattern character.  It is followed
	 * by a list of characters that are acceptable, or by a range
	 * (two characters separated by "-").
	 */
	
	if (*pattern == '[') {
	    pattern += 1;
	    while (1) {
		if ((*pattern == ']') || (*pattern == 0)) {
		    return 0;
		}
		if (*pattern == *string) {
		    break;
		}
		if (pattern[1] == '-') {
		    c2 = pattern[2];
		    if (c2 == 0) {
			return 0;
		    }
		    if ((*pattern <= *string) && (c2 >= *string)) {
			break;
		    }
		    if ((*pattern >= *string) && (c2 <= *string)) {
			break;
		    }
		    pattern += 2;
		}
		pattern += 1;
	    }
	    while ((*pattern != ']') && (*pattern != 0)) {
		pattern += 1;
	    }
	    goto thisCharOK;
	}
    
	/* If the next pattern character is backslash, just strip it off
	 * so we do exact matching on the character that follows.
	 */
	
	if (*pattern == '\\') {
	    pattern += 1;
	    if (*pattern == 0) {
		return 0;
	    }
	}

	/* There's no special character.  Just make sure that the next
	 * characters of each string match.
	 */
	
	if (*pattern != *string) {
	    return 0;
	}

	thisCharOK: pattern += 1;
	string += 1;
    }
}