Re: Tree Sitter and highlights.scm file

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 30 Nov 2023 11:35:42 +0000
> From: Tad Lispy <hello@tad-lispy.com>
> 
> Hi! It's my first post ever to a mailing list, so I hope I do everything
> right.  I'm also not very experienced with Emacs Lisp.
> 
> Here is my context. I'm working on a major mode for a new programming
> language.  I'd like to leverage the built-in Tree Sitter support for
> syntax highlighting.  My colleague works on the Tree Sitter grammar. In
> their repository there is a file called `queries/highlights.scm`. It's a
> scheme file that contains queries for different syntactic elements. Most
> other grammars I see also have such file, so I think it's standard in
> Tree Sitter grammars. I think it's generated by the `tree-sitter`
> command line program and later customized by a grammar author. It looks
> like all the necessary information for syntax highlighting is there.
> Since it's also a lisp, it should be possible to use this file to
> automatically derive font lock rules. But all examples of tree sitter
> modes I see re-implement all the queries in Emacs Lisp with
> `treesit-font-lock-rules` function. Why is that?
> 
> Before Emacs 29 there was a suite of 3rd party packages maintained by
> Tuấn-Anh Nguyễn. One of the packages is a library of Tree Sitter
> languages, that for each language contains the `highlights.scm` file.
> See for example
> https://github.com/emacs-tree-sitter/tree-sitter-langs/blob/master/queries/elm/highlights.scm.
> So it looks like previously it was possible to utilize this file. Can we
> still do it with Emacs 29?

Yuan, any comments?