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From: Yuan Fu <casouri@gmail.com>
To: Eli Zaretskii <eliz@gnu.org>
Cc: theodor thornhill <theo@thornhill.no>,
	geza.herman@gmail.com, Daniel Colascione <dancol@dancol.org>,
	emacs-devel@gnu.org
Subject: Re: treesit indentation "blinking"
Date: Sat, 1 Apr 2023 18:49:46 -0700	[thread overview]
Message-ID: <9F152CAA-6326-459F-84FF-87988B3A92B6@gmail.com> (raw)
In-Reply-To: <EED1F254-C8D2-4491-BF4F-C6BD57B9FE36@gmail.com>



> On Apr 1, 2023, at 12:39 PM, Yuan Fu <casouri@gmail.com> wrote:
> 
> 
> 
>> On Mar 30, 2023, at 7:58 AM, Eli Zaretskii <eliz@gnu.org> wrote:
>> 
>>> From: Herman, Géza <geza.herman@gmail.com>
>>> Cc: João Távora <joaotavora@gmail.com>,
>>> dgutov@yandex.ru, dancol@dancol.org,
>>> casouri@gmail.com, theo@thornhill.no, emacs-devel@gnu.org
>>> Date: Thu, 30 Mar 2023 12:26:16 +0200
>>> 
>>> Type this example into a c++-ts-mode buffer (I used "emacs -Q"):
>>> 
>>> --8<---------------cut here---------------start------------->8---
>>> int main() {
>>> for (;;) {
>>> printf("Hello world\n");
>>> }
>>> }
>>> --8<---------------cut here---------------end--------------->8---
>>> 
>>> This is how it will be indented as I wrote it here. c++-ts-mode doesn't
>>> re-indent anything during typing, even though it had the chance to do
>>> that, because electric-indent-mode is enabled by default, and
>>> electric-indent-chars contains the necessary characters.
>>> 
>>> Or, another example. Put the "void foo() { }" part first into a
>>> c++-ts-mode buffer, then write the main function:
>>> 
>>> --8<---------------cut here---------------start------------->8---
>>> int main() {
>>> int a = 0;
>>> for (;;) {
>>> printf("Hello!\n");
>>> }
>>> }
>>> 
>>> void foo() {
>>> }
>>> --8<---------------cut here---------------end--------------->8---
>>> 
>>> Again, c++-ts-mode doesn't indent anything.
>>> 
>>> If you change the example to contain "void foo();" instead of "void
>>> foo() { }", then indenting happens during typing the main function.
>>> 
>>> If you try adding "int a = 0;" into the first example, then it will be
>>> indented at typing the ";". But then for loop is still not get indented,
>>> and the buffer will look like this:
>>> 
>>> --8<---------------cut here---------------start------------->8---
>>> int main() {
>>> int a = 0;
>>> for (;;) {
>>> printf("Hello world\n");
>>> }
>>> }
>>> --8<---------------cut here---------------end--------------->8---
>>> 
>>> If you start by adding an empty comment, and then write the first
>>> example above the empty comment, the buffer will look like this:
>>> 
>>> --8<---------------cut here---------------start------------->8---
>>> int main() {
>>> for (;;) {
>>> printf("Hello world\n");
>>> }
>>> }
>>> 
>>> /**/
>>> --8<---------------cut here---------------end--------------->8---
>> 
>> Yuan and Theo, can you please look into these examples?  A simple
>> "C-c C-q" fixes the indentation, but the question is why it doesn't
>> happen while typing?
> 
> I’ll have a look!

Ok, the reason is that while you were typing, because the closing bracket was missing, the parser couldn’t produce a “good” parse tree. OTOH, the C parser can reasonably fix the source and produce something easy to use by our indenting rules (perhaps due to its simpler grammar) so you don’t see this problem in c-ts-mode.

If you enable electric-pair-mode so that the brackets are always balanced, then both c-ts-mode and c++-ts-mode should work fine.

Trying to solve this with heuristics is going against to grain, IMO. I think it’s acceptable to say that users of ts-modes should enabled electric-pair-mode, since it’s based on a parser, after all.

As for the blinking, I’ll let Theo to assess the solutions mentioned earlier (removing some indentation rules set on error nodes). 

Yuan


  reply	other threads:[~2023-04-02  1:49 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-22 20:49 treesit indentation "blinking" Daniel Colascione
2023-03-23  0:00 ` Yuan Fu
2023-03-23  0:07   ` Daniel Colascione
2023-03-23  1:02     ` Yuan Fu
2023-03-23  4:51       ` Daniel Colascione
2023-03-23 20:04         ` Yuan Fu
2023-03-23 21:10           ` Daniel Colascione
2023-03-23 21:24             ` Dmitry Gutov
2023-03-25  9:05               ` João Távora
2023-03-25 12:42                 ` Dmitry Gutov
2023-03-25 14:42                   ` Eli Zaretskii
2023-03-25 16:18                     ` João Távora
2023-03-28 22:11                       ` João Távora
2023-03-28 23:57                         ` Daniel Colascione
2023-03-29  2:26                         ` Eli Zaretskii
2023-03-29 22:30                           ` João Távora
2023-03-29 22:37                             ` Herman, Géza
2023-03-29 23:25                               ` João Távora
2023-03-30  7:47                                 ` Herman, Géza
2023-03-29 22:56                             ` Lynn Winebarger
2023-03-30  7:43                             ` Eli Zaretskii
2023-03-30  8:58                               ` Dmitry Gutov
2023-03-30  9:15                                 ` João Távora
2023-03-30  9:06                               ` João Távora
2023-03-30  9:20                                 ` Dmitry Gutov
2023-03-30  9:28                                   ` João Távora
2023-03-30  9:36                                     ` Dmitry Gutov
2023-03-30 10:00                                       ` João Távora
2023-03-30 16:29                                         ` Dmitry Gutov
2023-03-30 17:14                                           ` João Távora
2023-03-30 10:07                                 ` Eli Zaretskii
2023-03-30 10:26                                   ` Herman, Géza
2023-03-30 13:39                                     ` Eli Zaretskii
2023-03-30 15:03                                       ` Herman, Géza
2023-03-30 14:58                                     ` Eli Zaretskii
2023-04-01 19:39                                       ` Yuan Fu
2023-04-02  1:49                                         ` Yuan Fu [this message]
2023-04-02  5:31                                           ` Eli Zaretskii
2023-04-02 14:26                                           ` Alan Mackenzie
2023-04-02 15:48                                             ` João Távora
2023-04-02 17:04                                               ` Alan Mackenzie
2023-04-02 17:23                                                 ` João Távora
2023-04-02 17:51                                                   ` Eli Zaretskii
2023-04-02 18:04                                                     ` João Távora
2023-04-02 18:14                                                       ` Eli Zaretskii
2023-04-02 21:38                                                         ` João Távora
2023-04-02 21:21                                                   ` Dmitry Gutov
2023-04-02 21:40                                                     ` João Távora
2023-04-03  9:59                                                     ` Alan Mackenzie
2023-04-03 10:28                                                       ` João Távora
2023-04-03 12:07                                                       ` Dmitry Gutov
2023-04-03 12:56                                                         ` Alan Mackenzie
2023-04-03 20:58                                                           ` Dmitry Gutov
2023-04-03 21:59                                                         ` Daniel Colascione
2023-04-03 22:10                                                           ` Dmitry Gutov
2023-04-04  8:31                                                           ` João Távora
2023-04-07 14:20                                                           ` Daniel Martín
2023-04-08  1:32                                                             ` Dmitry Gutov
2023-04-08  2:42                                                               ` Yuan Fu
2023-04-08 18:59                                                               ` Daniel Martín
2023-04-03 21:47                                             ` parser error recovery algorithm vs " Stephen Leake
2023-04-04 12:01                                               ` John Yates
2023-04-04 13:40                                                 ` Dmitry Gutov
2023-04-04 16:00                                                   ` Stephen Leake
2023-04-04 13:50                                                 ` Stephen Leake
2023-04-04 14:05                                                   ` Dmitry Gutov
2023-03-30 11:05                                   ` João Távora
2023-03-30 14:00                                     ` Eli Zaretskii
2023-03-30 14:43                                       ` João Távora
2023-03-30 14:52                                         ` Eli Zaretskii
2023-03-30 15:42                                           ` João Távora
2023-03-25 16:14                   ` João Távora
2023-03-24 11:39             ` Eli Zaretskii

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