PATCH: reverse string subscripting

PATCH: reverse string subscripting

[Sven Wischnowsky]

This is from the debian bug list:

  % a=abcd
  % echo $a[1,(r)d]

didn't work, because it stopped one character too early trying to find
the matching substring for `d'.

Bye
  Sven

Index: Src/params.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/params.c,v
retrieving revision 1.32
diff -u -r1.32 params.c
--- Src/params.c	2001/02/14 23:37:39	1.32
+++ Src/params.c	2001/04/05 11:21:51
@@ -1113,6 +1113,8 @@
 		if (beg < 0)
 		    beg += len;
 		if (beg >= 0 && beg < len) {
+                    char *de = d + len;
+
 		    if (a2) {
 			if (down) {
 			    if (!hasbeg)
@@ -1128,7 +1130,7 @@
 				*t = sav;
 			    }
 			} else
-			    for (r = beg, t = d + beg; *t; r++, t++) {
+			    for (r = beg, t = d + beg; t <= de; r++, t++) {
 				sav = *t;
 				*t = '\0';
 				if (pattry(pprog, d) &&
@@ -1148,7 +1150,7 @@
 				    return r;
 			    }
 			} else
-			    for (r = beg + 1, t = d + beg; *t; r++, t++)
+			    for (r = beg + 1, t = d + beg; t <= de; r++, t++)
 				if (pattry(pprog, t) &&
 				    !--num)
 				    return r;

-- 
Sven Wischnowsky                         wischnow@informatik.hu-berlin.de

PATCH: 3.0.8 Re: PATCH: reverse string subscripting

[Bart Schaefer]

On Apr 5,  1:22pm, Sven Wischnowsky wrote:
} 
}   % a=abcd
}   % echo $a[1,(r)d]
} 
} didn't work, because it stopped one character too early trying to find
} the matching substring for `d'.

It appears that all 3.0 versions of zsh have this same bug, for both
forward and reverse pattern matches.  The third hunk below is just an
optimization (avoid redoing the strlen()).


Index: Src/params.c
===================================================================
--- Src/params.c	2000/09/27 03:18:54	1.1.1.6.4.6
+++ Src/params.c	2001/04/05 16:01:19
@@ -468,12 +468,14 @@
 		    }
 		return a2 ? -1 : 0;
 	    } else {
+	    	char *de;
 		d = getstrvalue(v);
 		if (!d || !*d)
 		    return 0;
+		de = d + strlen(d);
 		if (a2) {
 		    if (down)
-			for (r = -2, t = d + strlen(d) - 1; t >= d; r--, t--) {
+			for (r = -2, t = de; t >= d; r--, t--) {
 			    sav = *t;
 			    *t = '\0';
 			    if (domatch(d, c, 0) && !--num) {
@@ -482,7 +484,7 @@
 			    }
 			    *t = sav;
 		    } else
-			for (r = 0, t = d; *t; r++, t++) {
+			for (r = 0, t = d; t <= de; r++, t++) {
 			    sav = *t;
 			    *t = '\0';
 			    if (domatch(d, c, 0) && !--num) {
@@ -493,11 +495,11 @@
 			}
 		} else {
 		    if (down)
-			for (r = -1, t = d + strlen(d) - 1; t >= d; r--, t--) {
+			for (r = -1, t = de - 1; t >= d; r--, t--) {
 			    if (domatch(t, c, 0) && !--num)
 				return r;
 		    } else
-			for (r = 1, t = d; *t; r++, t++)
+			for (r = 1, t = d; t < de; r++, t++)
 			    if (domatch(t, c, 0) && !--num)
 				return r;
 		}

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net   

Re: PATCH: reverse string subscripting

[Bart Schaefer]

On Apr 5,  1:22pm, Sven Wischnowsky wrote:
} Subject: PATCH: reverse string subscripting
}
} This is from the debian bug list:
} 
}   % a=abcd
}   % echo $a[1,(r)d]
} 
} didn't work, because it stopped one character too early trying to find
} the matching substring for `d'.

Note the (r) is forward pattern matching, not reverse; (R) is reverse.
Your patch appears to have fixed the bug only for the forward direction:

zagzig% x=abcd
zagzig% echo $x[(r)d]
d
zagzig% echo $x[1,(r)d]
abcd
zagzig% echo $x[(R)d]  
d
zagzig% echo $x[1,(R)d]

zagzig% echo $x[1,(R)c]
abc
zagzig% 

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net   

Re: PATCH: reverse string subscripting

[Sven Wischnowsky]

Bart Schaefer wrote:

> ...
> 
> Note the (r) is forward pattern matching, not reverse; (R) is reverse.
> Your patch appears to have fixed the bug only for the forward direction:

Ahem.

Bye
  Sven

Index: Src/params.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/params.c,v
retrieving revision 1.33
diff -u -r1.33 params.c
--- Src/params.c	2001/04/05 11:24:17	1.33
+++ Src/params.c	2001/04/06 07:35:07
@@ -1118,7 +1118,7 @@
 		    if (a2) {
 			if (down) {
 			    if (!hasbeg)
-				beg = len - 1;
+				beg = len;
 			    for (r = beg, t = d + beg; t >= d; r--, t--) {
 				sav = *t;
 				*t = '\0';
@@ -1143,7 +1143,7 @@
 		    } else {
 			if (down) {
 			    if (!hasbeg)
-				beg = len - 1;
+				beg = len;
 			    for (r = beg + 1, t = d + beg; t >= d; r--, t--) {
 				if (pattry(pprog, t) &&
 				    !--num)

-- 
Sven Wischnowsky                         wischnow@informatik.hu-berlin.de