[mange@freemail.hu: next-single-property-change and narrowed buffers]

[mange@freemail.hu: next-single-property-change and narrowed buffers]

[Richard Stallman]

Would someone please fix this and DTRT?

------- Start of forwarded message -------
From: Magnus Henoch <mange@freemail.hu>
To: emacs-pretest-bug@gnu.org
Jabber-Id: legoscia@jabber.cd.chalmers.se
Date: Fri, 08 Sep 2006 15:04:00 +0200
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Subject: next-single-property-change and narrowed buffers
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	autolearn=failed version=3.0.4

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

The docsting of next-single-property-change promises that it will
never return a value equal to the position given, but it does if the
buffer is narrowed and the next property change occurs after the
narrowed region.  Test case:

(defun test-nspc ()
  (interactive)
  (with-current-buffer (get-buffer-create "*test-nspc*")
    (fundamental-mode)
    (erase-buffer)
    (insert (make-string 100 ?\ ))
    (add-text-properties 25 50 '(test-nspc t))
    (narrow-to-region 1 49)
    (let ((pos (point-min)))
      (while pos
	(message "pos is %s" pos)
	(let ((old-pos pos))
	  (setq pos (next-single-property-change pos 'test-nspc))
	  (when (and pos (<= pos old-pos))
	    (error "%s is <= %s" pos old-pos)))))))

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------- End of forwarded message -------

Re: Fwd: next-single-property-change and narrowed buffers

[Stefan Monnier]

> Would someone please fix this and DTRT?

> The docsting of next-single-property-change promises that it will
> never return a value equal to the position given, but it does if the
> buffer is narrowed and the next property change occurs after the
> narrowed region.  Test case:

I believe the patch below corrects this problem (for related functions as
well).  Can you confirm?


        Stefan


--- orig/src/textprop.c
+++ mod/src/textprop.c
@@ -1001,17 +1001,16 @@
 	 && (NILP (limit) || next->position < XFASTINT (limit)))
     next = next_interval (next);
 
-  if (NULL_INTERVAL_P (next))
-    return limit;
-  if (NILP (limit))
-    XSETFASTINT (limit, (STRINGP (object)
-			 ? SCHARS (object)
-			 : BUF_ZV (XBUFFER (object))));
-  if (!(next->position < XFASTINT (limit)))
+  if (NULL_INTERVAL_P (next)
+      || (next->position
+	  >= (INTEGERP (limit)
+	      ? XFASTINT (limit)
+	      : (STRINGP (object)
+		 ? SCHARS (object)
+		 : BUF_ZV (XBUFFER (object))))))
     return limit;
-
-  XSETFASTINT (position, next->position);
-  return position;
+  else
+    return make_number (next->position);
 }
 
 /* Return 1 if there's a change in some property between BEG and END.  */
@@ -1083,16 +1082,16 @@
 	 && (NILP (limit) || next->position < XFASTINT (limit)))
     next = next_interval (next);
 
-  if (NULL_INTERVAL_P (next))
-    return limit;
-  if (NILP (limit))
-    XSETFASTINT (limit, (STRINGP (object)
-			 ? SCHARS (object)
-			 : BUF_ZV (XBUFFER (object))));
-  if (!(next->position < XFASTINT (limit)))
+  if (NULL_INTERVAL_P (next)
+      || (next->position
+	  >= (INTEGERP (limit)
+	      ? XFASTINT (limit)
+	      : (STRINGP (object)
+		 ? SCHARS (object)
+		 : BUF_ZV (XBUFFER (object))))))
     return limit;
-
-  return make_number (next->position);
+  else
+    return make_number (next->position);
 }
 
 DEFUN ("previous-property-change", Fprevious_property_change,
@@ -1132,14 +1131,15 @@
 	 && (NILP (limit)
 	     || (previous->position + LENGTH (previous) > XFASTINT (limit))))
     previous = previous_interval (previous);
-  if (NULL_INTERVAL_P (previous))
-    return limit;
-  if (NILP (limit))
-    XSETFASTINT (limit, (STRINGP (object) ? 0 : BUF_BEGV (XBUFFER (object))));
-  if (!(previous->position + LENGTH (previous) > XFASTINT (limit)))
-    return limit;
 
-  return make_number (previous->position + LENGTH (previous));
+  if (NULL_INTERVAL_P (previous)
+      || (previous->position + LENGTH (previous)
+	  <= (INTEGERP (limit)
+	      ? XFASTINT (limit)
+	      : (STRINGP (object) ? 0 : BUF_BEGV (XBUFFER (object))))))
+    return limit;
+  else
+    return make_number (previous->position + LENGTH (previous));
 }
 
 DEFUN ("previous-single-property-change", Fprevious_single_property_change,
@@ -1184,14 +1184,15 @@
 	 && (NILP (limit)
 	     || (previous->position + LENGTH (previous) > XFASTINT (limit))))
     previous = previous_interval (previous);
-  if (NULL_INTERVAL_P (previous))
-    return limit;
-  if (NILP (limit))
-    XSETFASTINT (limit, (STRINGP (object) ? 0 : BUF_BEGV (XBUFFER (object))));
-  if (!(previous->position + LENGTH (previous) > XFASTINT (limit)))
-    return limit;
 
-  return make_number (previous->position + LENGTH (previous));
+  if (NULL_INTERVAL_P (previous)
+      || (previous->position + LENGTH (previous)
+	  <= (INTEGERP (limit)
+	      ? XFASTINT (limit)
+	      : (STRINGP (object) ? 0 : BUF_BEGV (XBUFFER (object))))))
+    return limit;
+  else
+    return make_number (previous->position + LENGTH (previous));
 }
 \f
 /* Callers note, this can GC when OBJECT is a buffer (or nil).  */

Re: Fwd: next-single-property-change and narrowed buffers

[Magnus Henoch]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

> I believe the patch below corrects this problem (for related functions as
> well).  Can you confirm?

Yes, this fixes the problem for me.  Thanks!

Magnus