PATCH: Re: Beginning of line matching

[Peter Stephenson <pws@xxxxxxx>]

"Bart Schaefer" wrote:
> On Mar 26, 12:31pm, Ian Lynagh wrote:
> } 
> } I would have expected ${FOO/(#s)/X} and ${${FOO/(#m)(#s)?/X$MATCH}:-X}
> } to be equivalent, but it seems that only the second one has the desired
> } effect when FOO is not empty. Is there a reason the first doesn't behave
> } as I expected?
> 
> AFAICT, it's because "start of string" is considered to begin with the
> first real character, thus after the implicit intial empty substring.
> 
> This should probably be considered a bug.
> 
> Compare ${FOO/()/X}, and also ${FOO//()/X} ...

It seems to be this simple to fix all these problems.  I think the test
for a non-zero-length match was to try and avoid possible problems
caused by infinite loops, but I don't see anything that would cause
infinite loops.  The parameter tests still pass (other forms of pattern
matching aren't affected).

This could probably go in 4.0, I suppose.

Index: Src/glob.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/glob.c,v
retrieving revision 1.25
diff -u -r1.25 glob.c
--- Src/glob.c	22 Feb 2002 17:28:06 -0000	1.25
+++ Src/glob.c	8 Apr 2002 17:38:39 -0000
@@ -2291,7 +2291,7 @@
 		for (; t < s + l; t++, patoffset++) {
 		    /* Find the longest match from this position. */
 		    set_pat_start(p, t-s);
-		    if (pattry(p, t) && patinput > t) {
+		    if (pattry(p, t)) {
 			char *mpos = patinput;
 			if (!(fl & SUB_LONG) && !(p->flags & PAT_PURES)) {
 			    char *ptr;
@@ -2371,7 +2371,7 @@
 		if (t > s && t[-1] == Meta)
 		    t--;
 		set_pat_start(p, t-s);
-		if (pattry(p, t) && patinput > t && !--n) {
+		if (pattry(p, t) && !--n) {
 		    /* Found the longest match */
 		    char *mpos = patinput;
 		    if (!(fl & SUB_LONG) && !(p->flags & PAT_PURES)) {

-- 
Peter Stephenson <pws@xxxxxxx>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 392070


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