REGEX Globber (Wild Card Matching)
johnk at wrq.com
johnk at wrq.com
Sat Feb 23 12:49:30 AEST 1991
02-24-91 Seattle, WA
Hmm. Choke. (Foot in mouth). After griping about buggy routines and
literally seconds after posting this code the first time, I received
a wonderful new test evaluation tool which allows you to perform
coverage analysis during testing. Sure enough I found that about
25% of the paths in the program were never traversed in my current
test battery. After swallowing my (overly large) pride and coming
up with a test battery which covered the entire path of the program
I found a couple of minor logic bugs involving literal escapes (\)
within other patterns (ie [..] and * sequences). I have repackaged
these routines and included also the makefile I use and the test
battery I use to make things a bit easier.
jbk
Here is a *IX wildcard globber I butchered, hacked and cajoled together
after seeing and hearing about and becoming disgusted with several similar
routines which had one or more of the following attributes: slow, buggy,
required large levels of recursion on matches, required grotesque levels
of recursion on failing matches using '*', full of caveats about usability
or copyrights.
I submit this without copyright and with the clear understanding that
this code may be used by anyone, for any reason, with any modifications
and without any guarantees, warrantee or statements of usability of any
sort.
Having gotten those cow chips out of the way, these routines are fairly
well tested and reasonably fast. I have made an effort to fail on all
bad patterns and to quickly determine failing '*' patterns. This parser
will also do quite a bit of the '*' matching via quick linear loops versus
the standard blind recursive descent.
This parser has been submitted to profilers at various stages of development
and has come through quite well. If the last millisecond is important to
you then some time can be shaved by using stack allocated variables in
place of many of the pointer follows (which may be done fairly often) found
in regex_match and regex_match_after_star (ie *p, *t).
No attempt is made to provide general [pat,pat] comparisons. The specific
subcases supplied by these routines is [pat,text] which is sufficient
for the large majority of cases (should you care).
Since regex_match may return one of three different values depending upon
the pattern and text I have made a simple shell for convenience (match()).
Also included is an is_pattern routine to quickly check a potential pattern
for regex special characters. I even placed this all in a header file for
you lazy folks!
Having said all that, here is my own reinvention of the wheel. Please
enjoy it's use and I hope it is of some help to those with need ....
jbk
==================== BEGIN of Listing ====================
Checksum: 2543766536 (verify or update this with "brik")
==================== MATCHMAK ====================
#
#
# Makefile for match.c
#
# Created 01-20-91 JBK
# Last Modified 02-13-91 JBK
#
#
CC = cl
#
# This is FLAGS for optimized version
#FLAGS = /c /AL /G0 /F 0FFF /Ox /W4
#
# This is FLAGS for optimized version with main
#FLAGS = /D TEST /AL /G0 /F 0FFF /Ox /W4
#
# This is FLAGS for debugging versions with main
FLAGS = /D TEST /AL /G0 /F 0FFF /Od /W4 /Zi /qc
match.exe: match.c match.h
$(CC) $(FLAGS) match.c
==================== MATCHTST.BAT ====================
@echo The following tests should match
match test? testy
match test* test
match tes*t test
match *test test
match t*s*t test
match t*s*t tesseract
match t?s? test
match ?s*t psyot
match [a-z]s*t asset
match s[!gh]t set
match t[a-ce]st test
match tea[ea-c]up teacup
match [a-fh-z]* jack
match \i\** i*hello
match [\[-\]] [
match [a-z\\] \
match [a-z%_] b
match [\]] ]
match \i?* itch
match \i?* it
match ?*?*?t test
match ?*?*?*?* test
match *\]*\**\?*\[ ]this*is?atest[
@echo The following tests should fail
match hello
match test test
match \ test
match t*s*t texxeract
match t?st tst
match test? test
match s[!e]t set
match [] ]
match [ [
match [\[-\] [
match [a atest
match [a- atest
match [a-z atest
match [a-]* atest
match [a-fh-z jack
match [a-fh-z\] jack
match [a-fh-z] jack
match ?*?*?t*? test
match *????? test
==================== MATCH.H ====================
/*
EPSHeader
File: match.h
Author: J. Kercheval
Created: Sat, 01/05/1991 22:27:18
*/
/*
EPSRevision History
J. Kercheval Wed, 02/20/1991 22:28:37 Released to Public Domain
*/
/*
Wildcard Pattern Matching
*/
#ifndef BOOLEAN
# define BOOLEAN int
# define TRUE 1
# define FALSE 0
#endif
/*----------------------------------------------------------------------------
*
* Match the pattern PATTERN against the string TEXT;
* return TRUE if it matches, FALSE otherwise.
*
* A match means the entire string TEXT is used up in matching.
*
* In the pattern string:
* `*' matches any sequence of characters
* `?' matches any character
* [SET] matches any character in the specified set,
* [!SET] or [^SET] matches any character not in the specified set.
*
* Note: the standard regex character '+' (one or more) should by
* simulated by using "?*" which is equivelant here.
*
* A set is composed of characters or ranges; a range looks like
* character hyphen character (as in 0-9 or A-Z). [0-9a-zA-Z_] is the
* minimul set of characters allowed in the [..] pattern construct.
* Other characters are allowed (ie. 8 bit characters) if your system
* will support them.
*
* To suppress the special syntactic significance of any of `[]*?!^-\',
* and match the character exactly, precede it with a `\'.
*
----------------------------------------------------------------------------*/
BOOLEAN match (char *pattern, char *text);
/*----------------------------------------------------------------------------
*
* Return TRUE if PATTERN has any special wildcard characters
*
----------------------------------------------------------------------------*/
BOOLEAN is_pattern (char *pattern);
==================== MATCH.C ====================
/*
EPSHeader
File: match.c
Author: J. Kercheval
Created: Sat, 01/05/1991 22:21:49
*/
/*
EPSRevision History
J. Kercheval Wed, 02/20/1991 22:29:01 Released to Public Domain
J. Kercheval Fri, 02/22/1991 15:29:01 fix '\' bugs (two :( of them)
*/
/*
Wildcard Pattern Matching
*/
#include "match.h"
#define ABORT 2 /* end of search indicator */
BOOLEAN regex_match_after_star (char *pattern, char *text);
/*----------------------------------------------------------------------------
*
* Return TRUE if PATTERN has any special wildcard characters
*
----------------------------------------------------------------------------*/
BOOLEAN is_pattern (char *p)
{
while ( *p ) {
switch ( *p++ ) {
case '?':
case '*':
case '[':
return TRUE;
case '\\':
if ( !*p++ ) return FALSE;
}
}
return FALSE;
}
/*----------------------------------------------------------------------------
*
* Match the pattern PATTERN against the string TEXT;
* return TRUE if it matches, FALSE otherwise.
*
* A match means the entire string TEXT is used up in matching.
*
* In the pattern string:
* `*' matches any sequence of characters
* `?' matches any character
* [SET] matches any character in the specified set,
* [!SET] or [^SET] matches any character not in the specified set.
*
* Note: the standard regex character '+' (one or more) should by
* simulated by using "?*" which is equivelant here.
*
* A set is composed of characters or ranges; a range looks like
* character hyphen character (as in 0-9 or A-Z). [0-9a-zA-Z_] is the
* minimul set of characters allowed in the [..] pattern construct.
* Other characters are allowed (ie. 8 bit characters) if your system
* will support them.
*
* To suppress the special syntactic significance of any of `[]*?!^-\',
* and match the character exactly, precede it with a `\'.
*
----------------------------------------------------------------------------*/
BOOLEAN regex_match ( register char *p, register char *t )
{
register char range_start, range_end; /* start and end in range */
BOOLEAN invert; /* is this [..] or [!..] */
BOOLEAN member_match; /* have I matched the [..] construct? */
BOOLEAN loop; /* should I terminate? */
for ( ; *p; p++, t++ ) {
/* if this is the end of the text then this is the end of the match */
if (!*t) {
return ( *p == '*' && *++p == '\0' ) ? TRUE : ABORT;
}
/* determine and react to pattern type */
switch ( *p ) {
/* single any character match */
case '?':
break;
/* multiple any character match */
case '*':
return regex_match_after_star (p, t);
/* [..] construct, single member/exclusion character match */
case '[': {
/* move to beginning of range */
p++;
/* check if this is a member match or exclusion match */
invert = FALSE;
if ( *p == '!' || *p == '^') {
invert = TRUE;
p++;
}
/* if closing bracket here or at range start then we have a
malformed pattern */
if ( *p == ']' ) {
return ABORT;
}
member_match = FALSE;
loop = TRUE;
while ( loop ) {
/* if end of construct then loop is done */
if (*p == ']') {
loop = FALSE;
continue;
}
/* matching a '!', '^', '-', '\' or a ']' */
if ( *p == '\\' ) {
range_start = range_end = *++p;
}
else {
range_start = range_end = *p;
}
/* if end of pattern then bad pattern (Missing ']') */
if (!range_start)
return ABORT;
/* check for range bar */
if (*++p == '-') {
/* get the range end */
range_end = *++p;
/* if end of pattern or construct then bad pattern */
if (range_end == '\0' || range_end == ']')
return ABORT;
/* special character range end */
if (range_end == '\\')
range_end = *++p;
/* move just beyond this range */
p++;
}
/* if the text character is in range then match found.
make sure the range letters have the proper
relationship to one another before comparison */
if ( range_start < range_end ) {
if (*t >= range_start && *t <= range_end) {
member_match = TRUE;
loop = FALSE;
}
}
else {
if (*t >= range_end && *t <= range_start) {
member_match = TRUE;
loop = FALSE;
}
}
}
/* if there was a match in an exclusion set then no match */
/* if there was no match in a member set then no match */
if ((invert && member_match) ||
!(invert || member_match))
return FALSE;
/* if this is not an exclusion then skip the rest of the [...]
construct that already matched. */
if (member_match) {
while (*p != ']') {
/* bad pattern (Missing ']') */
if (!*p)
return ABORT;
/* skip exact match */
if (*p == '\\') {
p++;
}
/* move to next pattern char */
p++;
}
}
break;
}
/* next character is quoted and must match exactly */
case '\\':
/* move pattern pointer to quoted char and fall through */
p++;
/* must match this character exactly */
default:
if (*p != *t)
return FALSE;
}
}
/* if end of text not reached then the pattern fails */
return !*t;
}
/*----------------------------------------------------------------------------
*
* recursively call regex_match with final segment of PATTERN and of TEXT.
*
----------------------------------------------------------------------------*/
BOOLEAN regex_match_after_star (register char *p, register char *t)
{
register BOOLEAN match;
register nextp;
/* pass over existing ? and * in pattern */
while ( *p == '?' || *p == '*' ) {
/* take one char for each ? */
if ( *p == '?' ) {
/* if end of text then no match */
if ( !*t++ ) {
return ABORT;
}
}
/* move to next char in pattern */
p++;
}
/* if end of pattern we have matched regardless of text left */
if ( !*p ) {
return TRUE;
}
/* get the next character to match which must be a literal or '[' */
nextp = *p;
if ( nextp == '\\' )
nextp = p[1];
/* Continue until we run out of text or definite result seen */
match = FALSE;
while ( match == FALSE ) {
/* a precondition for matching is that the next character
in the pattern match the next character in the text or that
the next pattern char is the beginning of a range. Increment
text pointer as we go here */
if ( nextp == *t || nextp == '[' ) {
match = regex_match(p, t);
}
/* if the end of text is reached then no match */
if ( !*t++ ) match = ABORT;
}
/* return result */
return match;
}
/*----------------------------------------------------------------------------
*
* This is a shell to regex_match to return only a true BOOLEAN value
*
----------------------------------------------------------------------------*/
BOOLEAN match( char *p, char *t)
{
return ( regex_match(p,t) == TRUE ) ? TRUE : FALSE;
}
#ifdef TEST
/*
* This test main expects as first arg the pattern and as second arg
* the match string. Output is yaeh or nay on match.
*/
#include <stdio.h>
int main(int argc, char *argv[])
{
if (argc == 3) {
if (is_pattern(argv[1])) {
if (match(argv[1],argv[2])) {
printf(" Match Successful\n");
}
else {
printf(" Match Fails\n");
}
}
else {
printf(" Bad Pattern\n");
}
}
else printf(" Bad Breath\n");
return(0);
}
#endif
==================== END of Listing ====================
--
John Kercheval -- 127 NW Bowdion Pl #105 -- Seattle, WA 98107-4960
Home(Voice): (206) 547-4676 -------- Work (Voice): (206) 324-0350
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