bug#62333: 30.0.50; Issue with tree-sitter syntax tree during certain changes

[Dmitry Gutov]

On 30/03/2023 19:04, Eli Zaretskii wrote:
> > Date: Thu, 30 Mar 2023 15:50:31 +0000
> > From: Gregory Heytings <gregory@heytings.org>
> > cc: Dmitry Gutov <dgutov@yandex.ru>, wkirschbaum@gmail.com, casouri@gmail.com,
> >      62333@debbugs.gnu.org
> >
> > > No, the idea is to create the parser with these restrictions to begin
> > > with.
> >
> > Could you perhaps explain, with some fictitious code, what kind of
> > solution you imagine?  I'm not sure I understand (euphemism for: I'm sure
> > I don't understand) the problem statement.
>
> Something like
>
>    (treesit-make-parser LANGUAGE BUFFER nil START END)

What kind of code would be calling this?

What happens when the user types a character before START? What happens 
when they delete a character at START or END? Or a whole line?

> and
>
>    (treesit-parser-set-included-ranges RANGES...)
>
> (the latter already exists).

Indeed, a way to do this using tree-sitter indeed already exists, 
offloading the parsing of the regions to tree-sitter. OTOH, this way we 
only get tree-sitter features sorted into regions (parse tree, 
indentation, highlighting).

Whatever other Lisp-level features we wanted to behave differently 
between regions, we'd have do implement them the old way.

> > In what way would the restrictions you have in mind be different from
> > those of a regular narrowing?
>
> User-defined narrowing will never contradict parser restrictions.

IOW, user-defined narrowing should be only for visual purposes, as 
described in another email. And perhaps to restrict movement (which is 
related: you can't move to where you can't see).