Re: Question on getting tree-sitter matches

[Abin Simon]

> Unfortunately, that’s currently not possible. Could you elaborate on why you 
> need such feature?

This came up when working with 
https://github.com/meain/evil-textobj-tree-sitter.

In this repo, I pull queries from Neovim repo which dos similar things,
https://github.com/nvim-treesitter/nvim-treesitter-textobjects. They
have custom predicates added and one of them is `#make-range!` which is
used to combine two captures together to form a new capture.

You can find an example at
https://github.com/nvim-treesitter/nvim-treesitter-textobjects/blob/5b2bcb9ca8315879181f468b37a897100d631005/queries/perl/textobjects.scm#L5

((patter_matcher_m
   (start_delimiter) @_start
   (end_delimiter) @_end) @regex.outer
 (#make-range! "regex.inner" @_start @_end))

In here, they use `#make-range!` to form a `regex.inner` predicate by
combining `@_start` and `@_end` markers' ranges. Since we do not have
support for this predicate, I was working around this by converting the
query into the following:

https://github.com/meain/evil-textobj-tree-sitter/blob/66819ee8547e439f003fcb0e1647acade194bd1a/queries/perl/textobjects.scm#LL5-L8C3

((patter_matcher_m
   (start_delimiter)  @regex.inner._start
   (end_delimiter)  @regex.inner._end) @regex.outer
 )

Once we have this, we use `regex.inner._start` and `regex.inner._end` to
do something similar (but we need to be able to restrict the search to a
single match group).

You can find the relevant part of the code from the plugin here:

https://github.com/meain/evil-textobj-tree-sitter/blob/66819ee8547e439f003fcb0e1647acade194bd1a/evil-textobj-tree-sitter-core.el#L157