* bug#19892: 25.0.50; hideshow: hs-hide-all-non-comment-function example infloop
@ 2015-02-17 22:45 Michael Heerdegen
2019-08-02 19:08 ` Lars Ingebrigtsen
2019-08-02 19:17 ` Lars Ingebrigtsen
0 siblings, 2 replies; 3+ messages in thread
From: Michael Heerdegen @ 2015-02-17 22:45 UTC (permalink / raw)
To: 19892; +Cc: ttn, dann
Hello,
(CCing the authors of hideshow specified in the file header)
in the header of hideshow.el, we have the following paragraph:
--8<---------------cut here---------------start------------->8---
;; Some languages (e.g., Java) are deeply nested, so the normal behavior
;; of `hs-hide-all' (hiding all but top-level blocks) results in very
;; little information shown, which is not very useful. You can use the
;; variable `hs-hide-all-non-comment-function' to implement your idea of
;; what is more useful. For example, the following code shows the next
;; nested level in addition to the top-level:
;;
;; (defun ttn-hs-hide-level-1 ()
;; (hs-hide-level 1)
;; (forward-sexp 1))
;; (setq hs-hide-all-non-comment-function 'ttn-hs-hide-level-1)
--8<---------------cut here---------------end--------------->8---
But this doesn't always work. For example, eval the above example in
emacs -Q, open "files.el", M-x hs-minor-mode, M-x hs-hide-all. You get
an infloop.
AFAICT the definition should be (or at least it works with that)
(defun ttn-hs-hide-level-1 ()
(when (hs-looking-at-block-start-p)
(hs-hide-level 1))
(forward-sexp 1))
Secondly, there is this comment in `hs-hide-all' which confuses me a bit:
;; Go to end of matched data to prevent from getting stuck
;; with an endless loop.
Which match data is meant there? It is either match data from before
hiding the block - then it should be documented that
`hs-hide-all-non-comment-function' must not change match data, I guess,
or the call should be wrapped into `save-match-data'. Or it is even the
case that `hs-hide-all-non-comment-function' must set the match data
(how?), which then should probably be documented.
Thanks,
Michael.
In GNU Emacs 25.0.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.14.5)
of 2015-02-15 on drachen
Repository revision: ba5bc0ee7c81f2122072bee162fcf1dbd8b2a8f2
Windowing system distributor `The X.Org Foundation', version 11.0.11602901
System Description: Debian GNU/Linux 8.0 (jessie)
Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GSETTINGS NOTIFY
LIBXML2 FREETYPE XFT ZLIB
Important settings:
value of $LC_ALL: de_DE.utf8
value of $LC_COLLATE: C
value of $LC_TIME: C
value of $LANG: de_DE.utf8
locale-coding-system: utf-8-unix
Major mode: Emacs-Lisp
Minor modes in effect:
magit-auto-revert-mode: t
rainbow-delimiters-mode: t
paredit-mode: t
on-screen-global-mode: t
ml-scale-mode: t
interaction-log-mode: t
highlight-defined-mode: t
helm-descbinds-mode: t
helm-mode: t
shell-dirtrack-mode: t
helm-occur-match-plugin-mode: t
helm-match-plugin-mode: t
helm-autoresize-mode: t
global-diff-hl-mode: t
diff-hl-mode: t
diff-auto-refine-mode: t
recentf-mode: t
which-function-mode: t
winner-mode: t
show-paren-mode: t
auto-image-file-mode: t
tooltip-mode: t
global-eldoc-mode: t
eldoc-mode: t
mouse-wheel-mode: t
prettify-symbols-mode: t
file-name-shadow-mode: t
global-font-lock-mode: t
font-lock-mode: t
blink-cursor-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
buffer-read-only: t
column-number-mode: t
line-number-mode: t
hs-minor-mode: t
^ permalink raw reply [flat|nested] 3+ messages in thread
* bug#19892: 25.0.50; hideshow: hs-hide-all-non-comment-function example infloop
2015-02-17 22:45 bug#19892: 25.0.50; hideshow: hs-hide-all-non-comment-function example infloop Michael Heerdegen
@ 2019-08-02 19:08 ` Lars Ingebrigtsen
2019-08-02 19:17 ` Lars Ingebrigtsen
1 sibling, 0 replies; 3+ messages in thread
From: Lars Ingebrigtsen @ 2019-08-02 19:08 UTC (permalink / raw)
To: Michael Heerdegen; +Cc: ttn, dann, 19892
Michael Heerdegen <michael_heerdegen@web.de> writes:
> in the header of hideshow.el, we have the following paragraph:
[...]
> ;; (defun ttn-hs-hide-level-1 ()
> ;; (hs-hide-level 1)
> ;; (forward-sexp 1))
> ;; (setq hs-hide-all-non-comment-function 'ttn-hs-hide-level-1)
>
> But this doesn't always work. For example, eval the above example in
> emacs -Q, open "files.el", M-x hs-minor-mode, M-x hs-hide-all. You get
> an infloop.
>
> AFAICT the definition should be (or at least it works with that)
>
> (defun ttn-hs-hide-level-1 ()
> (when (hs-looking-at-block-start-p)
> (hs-hide-level 1))
> (forward-sexp 1))
I've confirmed that the example still infloops in Emacs 27, and that
your example doesn't, so I've committed it to the Emacs trunk.
> Secondly, there is this comment in `hs-hide-all' which confuses me a bit:
>
> ;; Go to end of matched data to prevent from getting stuck
> ;; with an endless loop.
>
> Which match data is meant there? It is either match data from before
> hiding the block - then it should be documented that
> `hs-hide-all-non-comment-function' must not change match data, I guess,
> or the call should be wrapped into `save-match-data'. Or it is even the
> case that `hs-hide-all-non-comment-function' must set the match data
> (how?), which then should probably be documented.
Here's the code:
(progn
(goto-char (match-beginning 1))
(unless (if hs-hide-all-non-comment-function
(funcall hs-hide-all-non-comment-function)
(hs-hide-block-at-point t))
;; Go to end of matched data to prevent from getting stuck
;; with an endless loop.
(goto-char (match-end 0))))
`hs-hide-block-at-point' calls a lot of functions that change match
data, so presumably `hs-hide-all-non-comment-function' is allowed, too.
But this all seems nonsensical -- what `match-end' points to here seems
pretty random. So it looks like a bug to me.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
^ permalink raw reply [flat|nested] 3+ messages in thread
* bug#19892: 25.0.50; hideshow: hs-hide-all-non-comment-function example infloop
2015-02-17 22:45 bug#19892: 25.0.50; hideshow: hs-hide-all-non-comment-function example infloop Michael Heerdegen
2019-08-02 19:08 ` Lars Ingebrigtsen
@ 2019-08-02 19:17 ` Lars Ingebrigtsen
1 sibling, 0 replies; 3+ messages in thread
From: Lars Ingebrigtsen @ 2019-08-02 19:17 UTC (permalink / raw)
To: Michael Heerdegen; +Cc: ttn, dann, 19892
This was introduced (by me applying the following patch) seven years
ago.
Hm... Oh, I see what the brittle logic here really is. The code (by
default) calls this function:
(defun hs-hide-block-at-point (&optional end comment-reg)
[...]
(when (hs-looking-at-block-start-p)
And:
(defun hs-looking-at-block-start-p ()
"Return non-nil if the point is at the block start."
(and (looking-at hs-block-start-regexp)
(save-match-data (not (nth 8 (syntax-ppss))))))
So if the match is successful, but whatever (nth 8 (syntax-ppss)) means
doesn't, then we go to the end of that match data.
So it kinda works... But not if `hs-hide-all-non-comment-function' is
set. I'll try to rework this in a more logical fashion.
commit 43956923c00921499e0582f5da4cd739bc005240
Author: Sébastien Gross <seb@chezwam.org>
Date: Wed Apr 11 01:34:25 2012 +0200
(hs-hide-all): Don't infloop on comments that start in the middle of the line.
Fixes: debbugs:10496
diff --git a/lisp/progmodes/hideshow.el b/lisp/progmodes/hideshow.el
--- a/lisp/progmodes/hideshow.el
+++ b/lisp/progmodes/hideshow.el
@@ -804,7 +804,10 @@
(if (match-beginning 1)
- ;; we have found a block beginning
+ ;; We have found a block beginning.
(progn
(goto-char (match-beginning 1))
- (if hs-hide-all-non-comment-function
- (funcall hs-hide-all-non-comment-function)
- (hs-hide-block-at-point t)))
+ (unless (if hs-hide-all-non-comment-function
+ (funcall hs-hide-all-non-comment-function)
+ (hs-hide-block-at-point t))
+ ;; Go to end of matched data to prevent from getting stuck
+ ;; with an endless loop.
+ (goto-char (match-end 0))))
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-02-17 22:45 bug#19892: 25.0.50; hideshow: hs-hide-all-non-comment-function example infloop Michael Heerdegen
2019-08-02 19:08 ` Lars Ingebrigtsen
2019-08-02 19:17 ` Lars Ingebrigtsen
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