bug#58711: Treesit hangs when calling treesit-search-forward

[Wilhelm Kirschbaum]

forward-sexp works well with the below code, but when calling treesit-node-prev-sibling it will traverse up the list, which is then breaking backward-up-list when defining forward-sexp in the major mode.

(defun heex--treesit-largest-node-at-point ()
  "Find the largest node at point."
  (save-excursion
    (forward-comment (point-max))
    (let ((node-list
           (cl-loop for node = (treesit-node-at (point))
                    then (treesit-node-parent node)
                    while node
                    if (eq (treesit-node-start node)
                           (point))
                    collect node)))
      (car (last node-list)))))

(defun heex--treesit-backward-sexp ()
  "Forward sexp for Heex using treesit."
  (let* ((largest-node (heex--treesit-largest-node-at-point))
         (sibling (treesit-node-prev-sibling largest-node)))
    (when sibling
      (goto-char (treesit-node-start sibling)))))

(defun heex--treesit-forward-sexp ()
  "Forward sexp for Heex using treesit."
  (let* ((largest-node (heex--treesit-largest-node-at-point))
         (sibling (treesit-node-next-sibling largest-node)))
    (when sibling
      (goto-char (treesit-node-start sibling))
      (forward-comment (- (point-max))))))

On Thu, 10 Nov 2022 at 10:14, Yuan Fu <casouri@gmail.com> wrote:

> On Nov 9, 2022, at 10:44 PM, Wilhelm Kirschbaum <wilhelm@floatpays.co.za> wrote:
>
> I finally had some time to have a look. I don't see any more issues, thank you for the fantastic work on this. The defun-type-regexp is not enough to identify a defun in elixir this is the query I am using currently:
>
> (defvar elixir--treesit-query-defun
>   (let ((query `((call
>      target: (identifier) @type
>      (arguments
>       [
>        (alias) @name
>        (identifier) @name
>        (call target: (identifier)) @name
>        (binary_operator
>         left: (call target: (identifier)) @name
>         operator: "when")
>        ])
>      (:match ,elixir--definition-keywords-re @type)
>      ))))
>     (treesit-query-compile 'elixir query)))
>
> Regex will work in most cases I guess, but does not really deal with more complex queries for more complex cases like in elixir as there is not one type which is always the defun. elixir relies heavily on macros and different defun macros can be defined on the fly.

You can try the following procedure: use a regex to find the next/previous call, then perform some check on whether it’s indeed a defun, if not, keep searching for the next/previous call.


> Maybe if there is an option for using either a regex or a function?

Yes, instead of a regex you can pass a predicate function.

>
> I am also not sure how forward-sexp can work with the current treesit-search-forward-goto function as it does not take into consideration the level. Is there perhaps a way to move forward/backward, but do not jump to parents or children?

If you want to move in the same level, perhaps you can use treesit-next/prev/sibling?

Yuan