Re: emacs-tree-sitter and Emacs

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> As mentioned in some other message, this design becomes inefficient when
>> you have two windows displaying a large buffer, one display near the end,
>> and the other near the beginning, and you make changes at the beginning
>> of the buffer.  I haven't seen any performance bug-reports or complaints
>> about it, so it appears that those circumstances are very rare.
> Or you open a buffer and jumps to point-max,

I don't think this case is handled inefficiently by the approach taken
by `syntax-propertize`: it will take some time, yes, but it's largely
unavoidable in general (it's the same time that tree-sitter's and
CC-mode's up-front full parse have to pay for).

> OTOH if the whole buffer has been parsed, this two-window setup
> shouldn’t be slow when making changes because incremental parsing is fast,
> and we don’t need to re-parse the whole buffer.

That's supposed to be true with tree-sitter and CC-mode, but with
`syntax-propertize` we reparse everything between the first and the
second window, even though most of it was likely left untouched and
parsed identically to last time.


        Stefan