From: Noam Postavsky <npostavs@users.sourceforge.net>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: Emacs developers <emacs-devel@gnu.org>
Subject: Re: [Emacs-diffs] master c66aaa6: Recomplexify ‘delete-trailing-whitespace’ by treating \n as whitespace again
Date: Wed, 15 Mar 2017 23:04:38 -0400 [thread overview]
Message-ID: <CAM-tV--oe=9PL2cq2PrSZk5U20roLNcYcZCT=q=-ksFTdD03OA@mail.gmail.com> (raw)
In-Reply-To: <jwvvaraszp4.fsf-monnier+gmane.emacs.devel@gnu.org>
[-- Attachment #1: Type: text/plain, Size: 603 bytes --]
On Wed, Mar 15, 2017 at 10:52 PM, Stefan Monnier
<monnier@iro.umontreal.ca> wrote:
> Yes, it's normal: the "search" attempts a "match" from every whitespace.
> So if you have N consecutive whitespace chars in the middle of line,
> that gives you N attempts to "match" and every attempt takes O(N) steps
> to find that the end of the whitespace is not an LF.
>
> I don't understand how "\\s-+$" can be significantly faster than
> "[\s\t]+$" in this respect.
What? I though I said "\\s-+" is *slower* (though only by a factor of 2).
Anyway, how about the attached which removes the syntax table stuff.
[-- Attachment #2: 0001-Simplify-delete-trailing-whitespace-by-dropping-synt.patch --]
[-- Type: text/x-patch, Size: 1669 bytes --]
From 2275487232b96ca782ca671d60be002e3948a764 Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Wed, 15 Mar 2017 23:01:13 -0400
Subject: [PATCH] Simplify delete-trailing-whitespace by dropping syntax tables
* lisp/simple.el (delete-trailing-whitespace): Just match [[:blank:]]
independently of current syntax table.
---
lisp/simple.el | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/lisp/simple.el b/lisp/simple.el
index 369fbf7192..2cf8c13225 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -630,14 +630,13 @@ delete-trailing-whitespace
(save-excursion
(let ((end-marker (and end (copy-marker end))))
(goto-char (or start (point-min)))
- (with-syntax-table (make-syntax-table (syntax-table))
- ;; Don't delete formfeeds, even if they are considered whitespace.
- (modify-syntax-entry ?\f "_")
- (while (re-search-forward "\\s-$" end-marker t)
- (skip-syntax-backward "-" (line-beginning-position))
- (let ((b (point)) (e (match-end 0)))
- (when (region-modifiable-p b e)
- (delete-region b e)))))
+ ;; Note that trying to match all the trailing whitespace with
+ ;; just the regexp can be very slow (Bug#26079).
+ (while (re-search-forward "[[:blank:]]$" end-marker t)
+ (skip-syntax-backward "-" (line-beginning-position))
+ (let ((b (point)) (e (match-end 0)))
+ (when (region-modifiable-p b e)
+ (delete-region b e))))
(if end
(set-marker end-marker nil)
;; Delete trailing empty lines.
--
2.11.1
next prev parent reply other threads:[~2017-03-16 3:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20170315023157.29463.36647@vcs0.savannah.gnu.org>
[not found] ` <20170315023159.30AA520CAB@vcs0.savannah.gnu.org>
2017-03-15 11:28 ` [Emacs-diffs] master c66aaa6: Recomplexify ‘delete-trailing-whitespace’ by treating \n as whitespace again Stefan Monnier
2017-03-15 12:09 ` Noam Postavsky
2017-03-15 14:50 ` Stefan Monnier
2017-03-15 17:05 ` Noam Postavsky
2017-03-15 20:26 ` Stefan Monnier
2017-03-16 0:18 ` Noam Postavsky
2017-03-16 2:52 ` Stefan Monnier
2017-03-16 3:04 ` Noam Postavsky [this message]
2017-03-16 3:08 ` Stefan Monnier
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