From: Alan Mackenzie <acm@muc.de>
To: emacs-devel@gnu.org
Cc: martin rudalics <rudalics@gmx.at>,
Stefan Monnier <monnier@iro.umontreal.ca>
Subject: [acm@muc.de: Re: Emacs 22.2 release plans - request for a slight delay.]
Date: Fri, 7 Mar 2008 07:27:37 +0000 [thread overview]
Message-ID: <20080307072737.GA1334@muc.de> (raw)
----- Forwarded message from Alan Mackenzie <acm@muc.de> -----
Date: Thu, 6 Mar 2008 22:59:05 +0000
From: Alan Mackenzie <acm@muc.de>
To: Chong Yidong <cyd@stupidchicken.com>
Subject: Re: Emacs 22.2 release plans - request for a slight delay.
On Thu, Mar 06, 2008 at 10:38:57PM +0000, Alan Mackenzie wrote:
> Hi, Yidong,
[ .... ]
> I'm asking for a slight delay (perhaps over the weekend?) to fix a
> serious bug in C mode, namely:
> Subject: Re: Unbearably slow editing in .h files
> From: martin rudalics <rudalics@gmx.at> (and Stefan)
> Date: Sat, 23 Feb 2008 23:51:34 +0100
> Message-ID: <47C0A376.8080105@gmx.at>
> Visit lisp.h, go to the end of the buffer, and do
> M-x RET c-beginning-of-defun RET
> This is horrendously slow (~30 seconds).
> I've just had a look at c-beginning-of-defun, and I've narrowed the
> fault down to `c-in-knr-argdecl', where the code laboriously trundles
> back one paren pair at a time until it finds a "}" (or BOB). This is
> clearly suboptimal in a region with several hundred consecutive
> declarations without brace-blocks. There are ~900 consecutive
> paren-pairs in the tail of lisp.h.
> Even worse, c-in-knr-argdecl gets called twice, doubling the pain.
> Just how many paren/bracket pairs can there be in the K&R region of the
> header of a C function? There is no absolute limit, but such a region
> will typically look less extravagant than this:
> int foo (bar, baz, yuk)
> int bar [] ;
> int (*baz) (my_type) ;
> int (*) (void) (*yuk) (void) ;
> {
> , which has 7 such pairs. So perhaps if I put the limit at 32, this
> will be safe for any function not appearing in the Obfuscated C
> competition or deliberately written to break editors. :-)
> This will probably be a "quick and easy" change, taking, perhaps, an
> hour. However, it's probably worth while doing it calmly and carefully.
> ;-)
In fact, here's a provisional patch! C-M-a seems to run fast enough with
it, even in .../src/lisp.h.
*** cc-engine.el~ 2008-02-18 22:18:32.000000000 +0000
--- cc-engine.el 2008-03-06 22:55:31.263863296 +0000
***************
*** 6333,6339 ****
;; the searchable range.
(let* ((macro-start (c-query-macro-start))
(lim (max (or lim (point-min)) (or macro-start (point-min))))
! before-lparen after-rparen)
(narrow-to-region lim (c-point 'eol))
;; Search backwards for the defun's argument list. We give up if we
--- 6333,6340 ----
;; the searchable range.
(let* ((macro-start (c-query-macro-start))
(lim (max (or lim (point-min)) (or macro-start (point-min))))
! before-lparen after-rparen
! (pp-count-out 20)) ; Max number of paren/brace constructs before we give up
(narrow-to-region lim (c-point 'eol))
;; Search backwards for the defun's argument list. We give up if we
***************
*** 6355,6361 ****
;; {
(catch 'knr
! (while t ; go round one paren/bracket construct each time round.
(c-syntactic-skip-backward "^)]}")
(cond ((eq (char-before) ?\))
(setq after-rparen (point)))
--- 6356,6363 ----
;; {
(catch 'knr
! (while (> pp-count-out 0) ; go back one paren/bracket pair each time.
! (setq pp-count-out (1- pp-count-out))
(c-syntactic-skip-backward "^)]}")
(cond ((eq (char-before) ?\))
(setq after-rparen (point)))
--
Alan Mackenzie (Nuremberg, Germany).
----- End forwarded message -----
next reply other threads:[~2008-03-07 7:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-07 7:27 Alan Mackenzie [this message]
2008-03-16 14:11 ` [acm@muc.de: Re: Emacs 22.2 release plans - request for a slight delay.] martin rudalics
2008-03-16 19:36 ` Alan Mackenzie
2008-03-17 3:09 ` Stefan Monnier
2008-03-17 7:33 ` martin rudalics
2008-03-17 9:04 ` Alan Mackenzie
2008-03-17 9:30 ` martin rudalics
2008-03-25 23:17 ` Alan Mackenzie
2008-03-17 13:37 ` Stefan Monnier
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