bug#60894: 30.0.50; [PATCH] Add treesit-forward-sexp

[Theodor Thornhill]

Hi Emacs (also Juri and Mickey as you've expressed some interest for this)

This is an example patch for sexp movement with tree sitter.  I want to
put it out here to hopefully produce some discussion, sooner rather than
later.

Three initial questions:

1. What should a sexp be?

  Is it basically "everything", or is there a distincition between
  "word", "sexp" and "sentence"?  For lisp forward-sexp looks like a
  "jump over words, or a balanced pair of parens".  In other languages
  that can look a little weird - consider:

  ```
  foo().|bar().baz(); -> foo().bar|().baz(); -> foo().bar()|.baz();
  ```
  
  In a sense it could be considered "better", or at least distinct from
  forward-word to:

  ```
  foo().|bar().baz(); -> foo().bar()|.baz(); -> foo().bar().baz()|;
  ```

2. Should this new function be leveraged in transpose-sexps?

  IMO if the forward-sexp gets too close to forward-word, or
  forward-sentence we lose some nice properties with the current
  'treesit-transpose-sexps', namely (among others):

  ```
  f(String foo,| Integer bar) ->  void foo(Integer bar, String foo|)
  ```

  I know you Mickey have expressed some dissatisfaction with the current
  implementation - now is a good time to make some worthwhile
  improvements.


3. What are the "rules"?

  In c-mode, elisp-mode without paredit forward-sexp won't jump out of
  the current scope, however with paredit enabled it will.


If we simply want some code similar to this to live and slowly evolve I
guess we can install something like this patch after some tweaks and
iterate when we have more experience.

Anyway, I hope these questions and thoughs will spark some discussion,

Theo

0001-Add-treesit-forward-sexp.patch
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