Re: Using incremental parsing in Emacs

[Dmitry Gutov]

On 03.01.2020 22:05, Eli Zaretskii wrote:
> But that's just MO; I started this thread to maybe inspire someone to
> have a second look on the related features and propose ways of
> improving what we do today, both feature-wise and speed-wise, as I see
> quite a few complaints about lack of features and slowness in stuff
> like font-lock.

IME font-lock is slow:

- On long lines (which is hard to improve by simply implementing 
something in C),
- In certain major modes, on particular ones in CC Mode collection.

I imagine the latter is also caused by a relative complexity of the 
syntax in C++ and related languages, but also because, IIUC, CC Mode 
doesn't really do incremental parsing.

syntax-propertize-function, which is used by many other modes, kind of 
uses that paradigm, with a certain amount of success.

So the main thing I'd really expect from the new approach is "new 
features", i.e. ways to easier and more clearly express language syntax. 
Which, in turn, could entice our CC Mode developer to use it, with 
corresponding improvement in perceived performance. And, really, if 
TreeSitter's algorithmic complexity is good enough for us, it can 
probably be implemented in Lisp. With some critical section or two in C, 
maybe.