Re: Type Ahead Find

[Juri Linkov <juri@jurta.org>]

Richard Stallman <rms@gnu.org> writes:
>       But it allows to narrow the search only
>     to specific text part (such as e.g. in Firefox typing a ' before the
>     search string searches only links) which is currently not easily
>     implementable in Emacs.
>
> Making such a feature useful, and not intolerable, in the context
> of Emacs is not a simple matter.  I think I'd rather turn off any
> feature that makes some printing characters special in isearch.

The change I proposed has nothing to do with making some characters
special in isearch.

> Please let's not think about this now.  If you'd like to work
> on new features for after the release, how about implementing
> some of the features listed in etc/TODO?

This is not a new feature.  This is the change very closely related
to other recent fixes in isearch.el.  I want to finish all fixes
related to isearch.el before the next release.

Essentially, my proposed change is to make configurable the
currently hard-coded constraint imposed by `isearch-range-invisible'
in `isearch-search'.  The new variable `isearch-success-function'
will allow to override it with a user-defined function.

Also in the course of preparing this change I noticed some problems
in isearch.el related to searching of invisible text:

The lazy highlighting feature creates overlays even for matches inside
invisible texts.  A solution is to create a loop similar to the while-loop
in `isearch-search', but instead of `isearch-range-invisible' (which also
opens invisible overlays) to use the following condition in
`isearch-lazy-highlight-search':

    (text-property-any (match-beginning 0) (match-end 0)
                       'invisible nil)

This condition seems to be more correct even if it lazy-highlights
partly hidden matches.  An alternative condition

    (not (text-property-not-all (match-beginning 0) (match-end 0)
                                'invisible nil))

that lazy-highlights a match only if it is fully visible, doesn't
follow the logic of `isearch-range-invisible' used in `isearch-search'
which matches partly invisible text.

The current version of a patch is below:

Index: lisp/isearch.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/isearch.el,v
retrieving revision 1.261
diff -u -w -b -r1.261 isearch.el
--- lisp/isearch.el	18 Mar 2005 09:59:31 -0000	1.261
+++ lisp/isearch.el	20 Mar 2005 20:03:07 -0000
@@ -165,6 +165,11 @@
   "Function to save a function restoring the mode-specific isearch state
 to the search status stack.")
 
+(defvar isearch-success-function nil
+  "Function to report whether the new search match is considered successful.
+The function has two arguments: the positions of start and end of text
+matched by search.")
+
 ;; Search ring.
 
 (defvar search-ring nil
@@ -2039,7 +2046,8 @@
       (setq isearch-case-fold-search
 	    (isearch-no-upper-case-p isearch-string isearch-regexp)))
   (condition-case lossage
-      (let ((inhibit-point-motion-hooks search-invisible)
+      (let ((inhibit-point-motion-hooks
+	     (and (not isearch-success-function) search-invisible))
 	    (inhibit-quit nil)
 	    (case-fold-search isearch-case-fold-search)
 	    (search-spaces-regexp search-whitespace-regexp)
@@ -2052,12 +2060,15 @@
 		 isearch-string nil t))
 	  ;; Clear RETRY unless we matched some invisible text
 	  ;; and we aren't supposed to do that.
-	  (if (or (eq search-invisible t)
-		  (not isearch-success)
+	  (if (or (not isearch-success)
 		  (bobp) (eobp)
 		  (= (match-beginning 0) (match-end 0))
+		  (if isearch-success-function
+		      (funcall isearch-success-function
+			       (match-beginning 0) (match-end 0))
+		    (or (eq search-invisible t)
 		  (not (isearch-range-invisible
-			(match-beginning 0) (match-end 0))))
+			      (match-beginning 0) (match-end 0))))))
 	      (setq retry nil)))
 	(setq isearch-just-started nil)
 	(if isearch-success
@@ -2369,7 +2381,6 @@
                          isearch-lazy-highlight-window-end))))
     ;; something important did indeed change
     (lazy-highlight-cleanup t) ;kill old loop & remove overlays
-    (when (not isearch-error)
       (setq isearch-lazy-highlight-start-limit beg
 	    isearch-lazy-highlight-end-limit end)
       (setq isearch-lazy-highlight-window       (selected-window)
@@ -2384,7 +2395,7 @@
       (unless (equal isearch-string "")
 	(setq isearch-lazy-highlight-timer
 	      (run-with-idle-timer lazy-highlight-initial-delay nil
-				   'isearch-lazy-highlight-update))))))
+				 'isearch-lazy-highlight-update)))))
 
 (defun isearch-lazy-highlight-search ()
   "Search ahead for the next or previous match, for lazy highlighting.
@@ -2393,9 +2404,9 @@
 	(isearch-regexp isearch-lazy-highlight-regexp)
 	(search-spaces-regexp search-whitespace-regexp))
     (condition-case nil
-	(funcall (isearch-search-fun)
-		 isearch-lazy-highlight-last-string
-		 (if isearch-forward
+	(let ((retry t)
+	      (success nil)
+	      (bound (if isearch-forward
 		     (min (or isearch-lazy-highlight-end-limit (point-max))
 			  (if isearch-lazy-highlight-wrapped
 			      isearch-lazy-highlight-start
@@ -2403,8 +2414,22 @@
 		   (max (or isearch-lazy-highlight-start-limit (point-min))
 			(if isearch-lazy-highlight-wrapped
 			    isearch-lazy-highlight-end
-			  (window-start))))
-		 t)
+			      (window-start))))))
+	  (while retry
+	    (setq success
+		  (funcall (isearch-search-fun)
+			   isearch-lazy-highlight-last-string
+			   bound t))
+	    (if (or (not success)
+		    (eq (point) bound)
+		    (if isearch-success-function
+			(funcall isearch-success-function
+				 (match-beginning 0) (match-end 0))
+		      (text-property-any
+		       (match-beginning 0) (match-end 0)
+		       'invisible nil)))
+		(setq retry nil)))
+	  success)
       (error nil))))
 
 (defun isearch-lazy-highlight-update ()

-- 
Juri Linkov
http://www.jurta.org/emacs/