From: Tino Calancha <tino.calancha@gmail.com>
To: npostavs@users.sourceforge.net
Cc: 25410@debbugs.gnu.org
Subject: bug#25410: 26.0.50; Refine an unified diff hunk only if adds lines
Date: Thu, 12 Jan 2017 14:32:02 +0900 (JST) [thread overview]
Message-ID: <alpine.DEB.2.20.1701121429350.5813@calancha-pc> (raw)
In-Reply-To: <87wpe0zz0s.fsf@users.sourceforge.net>
On Wed, 11 Jan 2017, npostavs@users.sourceforge.net wrote:
> Tino Calancha <tino.calancha@gmail.com> writes:
>
>> From a performance point of view, current code in the case where
>> the hunk just adds lines is not as patological as the opposite one.
>> M-! git diff ef8c9f8^ ef8c9f8 RET
>
> By the way, with Emacs 25.1, I notice trying to refine this gives me a
> regex stack overflow error. Probably my recent changes to the regex
> stack limits allow Emacs to spend more time on this instead of
> overflowing.
Yeah, your commit has revealed such nasty regexp's. Before we get
a stack overflow and the refine of the hunk ends.
>> We might use the first patch in this thread or the following one:
>
> It's probably okay to use the first patch (i.e., don't bother checking
> for delete-only hunks), with an added comment about the asymmetry. But
> I think it would be better to change diff-refine-hunk to avoid the
> inefficient regex, like this:
I agree with you it's better to not use such heavy regexp matching
too many lines.
Your patch LGTM. Thank very much.
>From f5ea9e585b535390a69e442d83ecbeec8e8e18d2 Mon Sep 17 00:00:00 2001
>From: Noam Postavsky <npostavs@gmail.com>
>Date: Wed, 11 Jan 2017 23:21:38 -0500
>Subject: [PATCH v1] Avoid inefficient regex in diff-refine-hunk
(Bug#25410)
>
>* lisp/vc/diff-mode.el (diff--forward-while-leading-char): New function.
>(diff-refine-hunk): Use it instead of trying to match multiple lines
>with a single lines.
>---
> lisp/vc/diff-mode.el | 27 +++++++++++++++++----------
> 1 file changed, 17 insertions(+), 10 deletions(-)
>
>diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
>index 9dfcd94..915e0b1 100644
>--- a/lisp/vc/diff-mode.el
>+++ b/lisp/vc/diff-mode.el
>@@ -2062,6 +2062,15 @@ diff-refine-preproc
> (declare-function smerge-refine-subst "smerge-mode"
> (beg1 end1 beg2 end2 props-c &optional preproc props-r
props-a))
>
>+(defun diff--forward-while-leading-char (char bound)
>+ "Move point until reaching a line not starting with CHAR.
>+Return new point, if it was moved."
>+ (let ((pt nil))
>+ (while (and (< (point) bound) (eql (following-char) char))
>+ (forward-line 1)
>+ (setq pt (point)))
>+ pt))
>+
> (defun diff-refine-hunk ()
> "Highlight changes of hunk at point at a finer granularity."
> (interactive)
>@@ -2081,16 +2090,14 @@ diff-refine-hunk
> (goto-char beg)
> (pcase style
> (`unified
>- (while (re-search-forward
>- (eval-when-compile
>- (let ((no-LF-at-eol-re "\\(?:\\\\.*\n\\)?"))
>- (concat "^\\(?:-.*\n\\)+" no-LF-at-eol-re
>- "\\(\\)"
>- "\\(?:\\+.*\n\\)+" no-LF-at-eol-re)))
>- end t)
>- (smerge-refine-subst (match-beginning 0) (match-end 1)
>- (match-end 1) (match-end 0)
>- nil 'diff-refine-preproc props-r
props-a)))
>+ (while (re-search-forward "^-" end t)
>+ (let ((beg-del (progn (beginning-of-line) (point)))
>+ beg-add end-add)
>+ (when (and (setq beg-add (diff--forward-while-leading-char
?- end))
>+ (or (diff--forward-while-leading-char ?\\ end)
t)
>+ (setq end-add (diff--forward-while-leading-char
?+ end)))
>+ (smerge-refine-subst beg-del beg-add beg-add end-add
>+ nil 'diff-refine-preproc props-r
props-a)))))
> (`context
> (let* ((middle (save-excursion (re-search-forward "^---")))
> (other middle))
>--
>2.9.3
>
next prev parent reply other threads:[~2017-01-12 5:32 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-10 10:08 bug#25410: 26.0.50; Refine an unified diff hunk only if adds lines Tino Calancha
2017-01-10 14:22 ` npostavs
2017-01-10 15:07 ` Tino Calancha
2017-01-11 2:49 ` Tino Calancha
2017-01-11 8:13 ` Tino Calancha
[not found] ` <87wpe0zz0s.fsf@users.sourceforge.net>
2017-01-12 5:32 ` Tino Calancha [this message]
2017-01-13 4:50 ` npostavs
2017-01-13 6:14 ` Tino Calancha
2017-01-13 12:11 ` Tino Calancha
2017-01-13 16:31 ` Noam Postavsky
2017-01-14 5:38 ` Tino Calancha
2017-01-19 1:55 ` npostavs
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