Subject: bug#67262: python-ts-mode cannot identify triple-quoted-strings

From: Dmitry Gutov <[email-masked]>
Date: Mon, 27 Nov 2023 02:05:10 +0200

On 27/11/2023 01:43, Yuan Fu wrote:
> 
> On 11/26/23 6:58 AM, Dmitry Gutov wrote:
>> On 26/11/2023 04:04, Dmitry Gutov wrote:
>>> As for what to do about this one -- probably something involving 
>>> syntax-propertize-extend-region-functions, adding an entry which 
>>> would initialize the parser, but not call syntax-ppss-flush-cache 
>>> directly (or at least not just that). It would signal the earlier 
>>> position to extend to through some dynamic variable. This is getting 
>>> tricky enough to move from the individual major modes into treesit.el 
>>> proper, I think.
>>
>> Alternatively, we'd trigger updates eagerly from within 
>> treesit_record_change -- that would make it slower, invalidating the 
>> comment above it. Not sure by how much, though.
> 
> It seems to me that what we need is to force a re-parse at the beginning 
> of syntax-propertize or in syntax-ppss-flush-cache; the re-parse would 
> cause the notifier to run, which runs python--treesit-parser-after-change.

syntax-ppss-flush-cache is called by edits (and by the re-parse). It 
seems like it will be odd to have execution the other way around and/or 
add some hook into it which would call the re-parse and extend the 
region to be invalidated.

syntax-propertize could have another hook added, yes. Or an advice.

But it seems better to reuse some of the existing hooks, such as 
syntax-propertize-extend-region-functions. It treesit.c provided a way 
to fetch the newly-invalidated region, the treesit-major-mode-setup 
could add a new function to syntax-propertize-extend-region-functions 
which would invoke that feature. But even now it can instantiate the 
parse, which would call treesit-force-reparse internally, and then 
collect the info from the callbacks.

And yet another way - is to extend the region to be propertized from 
inside the major mode's syntax-propertize-function, invalidating some 
earlier entries too. The main problem with that, I think, is that every 
ts mode will have to repeat that trick. And that authors would have to 
know to do that. How to make that easier and more obvious, is a question.

Finally, if I'm right that bug#66732 has a similar cause, then a shared 
solution that can be reused by syntax and font-lock (or preferably just 
fix both in the same place) would be ideal.

> I'm not quite sure about how do we cause this re-parse. The 
> straightforward approach would be calling treesit-force-reparse[1] in 
> syntax-propertize/syntax-ppss-flush-cache. But ideally I'd like to keep 
> tree-sitter transparent for syntax.el. Maybe we can add a hook in 
> syntax-propertize/syntax-ppss-flush-cache.
> 
> [1] This function doesn't exist yet, but it's easy to define in lisp.

treesit-parser-root-node calls it anyway and does little else, so we 
could get by with just using it.