Subject: Re: bug#10145: 24.0.91; Word Isearch backward

From: Juri Linkov <[email-masked]>
Date: Tue, 29 Nov 2011 02:33:06 +0200

> from "emacs -Q", type: `a a RET b b RET M-s w C-r a a SPC b b'.
>
> At this point, the Isearch (word-type, backward) should succeed, but I
> see a failing one.

Thanks, this is a bug.

The comment in `isearch-search-and-update' says:

    ;; In reverse search, adding stuff at
    ;; the end may cause zero or many more chars to be
    ;; matched, in the string following point.
    ;; Allow all those possibilities without moving point as
    ;; long as the match does not extend past search origin.

and it calls `looking-at' to implement this.
But it doesn't take into account word search.

The following patch fixes this bug by using `wordify'
now exposed to Lisp:

=== modified file 'lisp/isearch.el'
--- lisp/isearch.el	2011-11-28 06:59:03 +0000
+++ lisp/isearch.el	2011-11-29 00:30:33 +0000
@@ -1648,8 +1643,10 @@ (defun isearch-search-and-update ()
 		   (if (and (eq case-fold-search t) search-upper-case)
 		       (setq case-fold-search
 			     (isearch-no-upper-case-p isearch-string isearch-regexp)))
-		   (looking-at (if isearch-regexp isearch-string
-				 (regexp-quote isearch-string))))
+		   (looking-at (cond
+				(isearch-regexp isearch-string)
+				(isearch-word (wordify isearch-string t))
+				(t (regexp-quote isearch-string)))))
 	       (error nil))
 	     (or isearch-yank-flag
 		 (<= (match-end 0)

=== modified file 'src/search.c'
--- src/search.c	2011-11-27 18:17:40 +0000
+++ src/search.c	2011-11-29 00:29:22 +0000
@@ -2078,13 +2078,12 @@ (at your option) any later version.
   XSETBUFFER (last_thing_searched, current_buffer);
 }
 
-/* Given STRING, a string of words separated by word delimiters,
-   compute a regexp that matches those exact words separated by
-   arbitrary punctuation.  If LAX is nonzero, the end of the string
-   need not match a word boundary unless it ends in whitespace.  */
-
-static Lisp_Object
-wordify (Lisp_Object string, int lax)
+DEFUN ("wordify", Fwordify, Swordify, 1, 2, 0,
+       doc: /* Given STRING, a string of words separated by word delimiters,
+compute a regexp that matches those exact words separated by
+arbitrary punctuation.  If LAX is non-nil, the end of the string
+need not match a word boundary unless it ends in whitespace.  */)
+  (Lisp_Object string, Lisp_Object lax)
 {
   register unsigned char *o;
   register EMACS_INT i, i_byte, len, punct_count = 0, word_count = 0;
@@ -2125,7 +2124,7 @@ (at your option) any later version.
     }
 
   adjust = - punct_count + 5 * (word_count - 1)
-    + ((lax && !whitespace_at_end) ? 2 : 4);
+    + ((!NILP (lax) && !whitespace_at_end) ? 2 : 4);
   if (STRING_MULTIBYTE (string))
     val = make_uninit_multibyte_string (len + adjust,
 					SBYTES (string)
@@ -2162,7 +2161,7 @@ (at your option) any later version.
       prev_c = c;
     }
 
-  if (!lax || whitespace_at_end)
+  if (NILP (lax) || whitespace_at_end)
     {
       *o++ = '\\';
       *o++ = 'b';
@@ -2220,7 +2219,7 @@ (at your option) any later version.
 Optional fourth argument is repeat count--search for successive occurrences.  */)
   (Lisp_Object string, Lisp_Object bound, Lisp_Object noerror, Lisp_Object count)
 {
-  return search_command (wordify (string, 0), bound, noerror, count, -1, 1, 0);
+  return search_command (Fwordify (string, Qnil), bound, noerror, count, -1, 1, 0);
 }
 
 DEFUN ("word-search-forward", Fword_search_forward, Sword_search_forward, 1, 4,
@@ -2234,7 +2233,7 @@ (at your option) any later version.
 Optional fourth argument is repeat count--search for successive occurrences.  */)
   (Lisp_Object string, Lisp_Object bound, Lisp_Object noerror, Lisp_Object count)
 {
-  return search_command (wordify (string, 0), bound, noerror, count, 1, 1, 0);
+  return search_command (Fwordify (string, Qnil), bound, noerror, count, 1, 1, 0);
 }
 
 DEFUN ("word-search-backward-lax", Fword_search_backward_lax, Sword_search_backward_lax, 1, 4,
@@ -2252,7 +2251,7 @@ (at your option) any later version.
 Optional fourth argument is repeat count--search for successive occurrences.  */)
   (Lisp_Object string, Lisp_Object bound, Lisp_Object noerror, Lisp_Object count)
 {
-  return search_command (wordify (string, 1), bound, noerror, count, -1, 1, 0);
+  return search_command (Fwordify (string, Qt), bound, noerror, count, -1, 1, 0);
 }
 
 DEFUN ("word-search-forward-lax", Fword_search_forward_lax, Sword_search_forward_lax, 1, 4,
@@ -2270,7 +2269,7 @@ (at your option) any later version.
 Optional fourth argument is repeat count--search for successive occurrences.  */)
   (Lisp_Object string, Lisp_Object bound, Lisp_Object noerror, Lisp_Object count)
 {
-  return search_command (wordify (string, 1), bound, noerror, count, 1, 1, 0);
+  return search_command (Fwordify (string, Qt), bound, noerror, count, 1, 1, 0);
 }
 
 DEFUN ("re-search-backward", Fre_search_backward, Sre_search_backward, 1, 4,
@@ -3229,6 +3228,7 @@ (at your option) any later version.
   defsubr (&Sposix_string_match);
   defsubr (&Ssearch_forward);
   defsubr (&Ssearch_backward);
+  defsubr (&Swordify);
   defsubr (&Sword_search_forward);
   defsubr (&Sword_search_backward);
   defsubr (&Sword_search_forward_lax);

Actually there are more places that require the Lisp call to `wordify'
like in `isearch-occur':

=== modified file 'lisp/isearch.el'
--- lisp/isearch.el	2011-11-28 06:59:03 +0000
+++ lisp/isearch.el	2011-11-29 00:30:33 +0000
@@ -1447,12 +1447,7 @@ (defun isearch-occur (regexp &optional n
   (interactive
    (list
     (cond
-     (isearch-word (concat "\\b" (replace-regexp-in-string
-				  "\\W+" "\\W+"
-				  (replace-regexp-in-string
-				   "^\\W+\\|\\W+$" "" isearch-string)
-				  nil t)
-			   "\\b"))
+     (isearch-word (wordify isearch-string))
      (isearch-regexp isearch-string)
      (t (regexp-quote isearch-string)))
     (if current-prefix-arg (prefix-numeric-value current-prefix-arg))))