Re: Tree-sitter integration on feature/tree-sitter

[Yoav Marco]

Yoav Marco <yoavm448@gmail.com> writes:

> Okay, so the problem here is that neovim supports making up arbitrary
> captures as a range over other captures: (#make-range! "c" @a @b) means
> "make a new capture @c that spans from @a to @b". It helps when you e.g
> want to make a capture spanning only two children of a node and not the
> other children.
>
> The problem is, making up new captures in Lisp isn't trivial, it would
> need special support form the C side.
>
> Could we support this?
>
> 1. We could allow a special case where if Lisp predicate return a list
>    (name beg end) that would have the same effect as "make new capture
>    @c with range @a, @b".
>
> 2. But captures are returned from treesit-query-capture as pairs of
>    (capture-name . node), and we can't just make up a node with
>    arbitrary range.
>
> 3. We could report non-boolean capture results by just appending that
>    result to the list of pairs, but that just adds complexity to users
>    of treesit-query-capture. And it doesn't support the simpler use case
>    of 1, where it's just reported as a normal capture.


I dug a little through the neovim code. #make-range! is implemented in
nvim-treesitter, not mainline neovim. And they don't create a new node
for the range, just compute the range itself.

I think the best course of action is to support elisp predicates in some
way, and let users post-process the output of treesit-query-capture if
they added queries that return non-boolean results.

> Abin Simon <abinsimon10@gmail.com> writes:
>
>> I ran into similar issues in the meain/evil-textobj-tree-sitter and had
>> to write scritps to convert them to something that works in emacs.

I see you wrote a go program to pre-process #make-range!. I also had to do
something similar in
https://github.com/emacs-tree-sitter/tree-sitter-langs/pull/99
due to predicate incompatibility, though I do it in Elisp right after
reading the query file. So I guess it's a valid solution too.