Subject: bug#16800: 24.3; flyspell works slow on very short words at the end of big file

From: Agustin Martin <[email-masked]>
Date: Sun, 23 Feb 2014 02:26:00 +0100

2014-02-22 22:03 GMT+01:00 Eli Zaretskii <[email-masked]>:

> > Date: Sat, 22 Feb 2014 22:55:11 +0400
> > From: Aleksey Cherepanov <[email-masked]>
> >
> > > > Emacs words are language sensitive too.
> > >
> > > But not in the same way as ispell/flyspell is.  The CASECHARS,
> > > NON-CASECHARS, and OTHERCHARS parameters of the dictionary are only
> > > taken into account by ispell/flyspell.
> >
> > I think one could define a dictionary like: ("my" "[a]" "[^a]" "" ...)
> > So the only letter for flyspell words is "a". That way "qqaaqqaaqq" is
> > one word for emacs and two words with garbage around for flyspell. I
> > think my solution fails in such case.
>
> It's more complex than that: with some languages, and at least with
> aspell, we take these parameters from the dictionary.  So they cannot
> be known in advance in some cases.
>

Hi,

Not yet sure if  I am missing something important, but I am playing with a
regexp search in flyspell-word-search-* functions based on what flyspell
thinks is the word to spellcheck (`word') and what thinks should not be
part of a word (`NOTCASECHARS'). Since no OTHERCHARS is used there may be
some intermediate matches being false positives that will be discarded once
flyspell-word checks them.

I have tested this in Alekseys's file and is apparently working well and in
this particular case with much better efficiency. Need to think about more
ad-hoc situations where it may fail or slow down things. Suggestions for
possible failures are welcome.

Patch is attached. I did the tests against an old and patched version of
flyspell.el (that shipped with Debian stable) and built the patch for it.
Should apply and work similarly in trunk's flyspell.el.

-- 
Agustin
--- flyspell.el.orig	2014-02-23 02:17:03.680107519 +0100
+++ flyspell.el	2014-02-23 02:50:50.634625248 +0100
@@ -1050,8 +1050,19 @@
   (save-excursion
     (let ((r '())
 	  (inhibit-point-motion-hooks t)
+	  (flyspell-not-casechars (flyspell-get-not-casechars))
 	  p)
-      (while (and (not r) (setq p (search-backward word bound t)))
+      (while 
+	  (and (not r) 
+	       (setq p 
+		     (re-search-backward
+		      (concat
+		       "\\(" flyspell-not-casechars "\\|\\b\\)"
+		       "\\(" word "\\)"
+		       flyspell-not-casechars
+		       )
+		      bound t)))
+	(goto-char (match-beginning 2))
 	(let ((lw (flyspell-get-word)))
 	  (if (and (consp lw)
 		   (if ignore-case
@@ -1068,8 +1079,19 @@
   (save-excursion
     (let ((r '())
 	  (inhibit-point-motion-hooks t)
+	  (flyspell-not-casechars (flyspell-get-not-casechars))
 	  p)
-      (while (and (not r) (setq p (search-forward word bound t)))
+      (while 
+	  (and (not r) 
+	       (setq p 
+		     (re-search-forward 
+		      (concat
+		       flyspell-not-casechars
+		       "\\(" word "\\)"
+		       "\\(" flyspell-not-casechars "\\|\\b\\)"
+		       )
+		      bound t)))
+	(goto-char (match-beginning 1))
 	(let ((lw (flyspell-get-word)))
 	  (if (and (consp lw) (string-equal (car lw) word))
 	      (setq r p)