Re: Update on tree-sitter structure navigation

[Hugo Thunnissen]

Ihor Radchenko <yantar92@posteo.net> writes:

> Yuan Fu <casouri@gmail.com> writes:
>
>> In the months after wrapping up tree-sitter stuff in emacs-29, I was
>> thinking about how to implement structural navigation and extracting
>> information from the parser with tree-sitter. In emacs-29 we have
>> things like treesit-beginning/end-of-defun, and treesit-defun-name. I
>> was thinking maybe we can generalize this to support getting arbitrary
>> “thing” at point, move around them, and getting information like the
>> name of a defun, its arglist, parent of a class, type of an variable
>> declaration, etc, in a language-agnostic way.
>
> Note that Org mode also does all of these using
> https://orgmode.org/worg/dev/org-element-api.html
>
> It would be nice if we could converge to more consistent interface
> across all the modes. For example, by extending `thing-at-point' to handle
> parsed elements, not just simplistic regexp-based "thing" boundaries
> exposed by `thing-at-point' now.
>
> Org approaches getting name/begin/end/arguments using a common API:
>
> (org-element-property :begin NODE)
> (org-element-property :end NODE)
> (org-element-property :contents-begin NODE)
> (org-element-property :contents-end NODE)
> (org-element-property :name NODE)
> (org-element-property :args NODE)
>
> Language-agnostic "thing"s will certainly be welcome, especially given
> that tree-sitter grammars use inconsistent naming schemes, which have to
> be learned separately, and may even change with grammar versions.
>
> I think that both NODE types and attributes can be standardized.
>

It would be great to see standardization that can work with more than
just tree-sitter.  Depending on how extensive such a generic NODE type
and accompanying API are, I could see standardization of a lot of things
that are currently implemented in major modes, to name a few:

- indentation
- fontification
- thing-at-point
- imenu
- simple forms of completion (variables, function names in buffer)

I have some idea of the underpinnings, but I have never implemented a
full major mode so it is hard for me to judge the practicality of
this. How much would be practical to standardize, without needlessly
complicated/resource-heavy abstractions?