bug#66989: 30.0.50; tree-sitter: treesit-defun-at-point wrong behavior in python-ts-mode

[Yuan Fu]

> On Nov 9, 2023, at 12:13 AM, Yuan Fu <casouri@gmail.com> wrote:
> 
> 
> 
>> On Nov 8, 2023, at 12:37 PM, Zubarev Dv <dvzubarev@yandex.ru> wrote:
>> 
>> Initially I thought that it is the second definition.  It seems to be more 
>> intuitive. But after reading code, I was sure its the first case.
>> 
>> But I actually don't sure that all three "things" are needed at once.
>> For example,  I think for `thing-at-point` only enclosing parent is needed.
>> If parent is nil, it may optionally fallback to the next sibling thing.
>> `treesit--navigate-thing` uses only `parent` and `next` or `prev`.
>> I was playing with creating evil text objects, based on your awesome
>> work with "things".
>> I ended up extracting the second part (;; 2. Find the parent) from 
>> `treesit--things-around`.
>> Since I only need to find enclosing parent and I don't want to pay for
>> what I don't use.
>> So it seems no function uses all results from `treesit--things-around`.
>> 
>> Maybe it makes sense to decompose `treesit--things-around` into two
>> functions:
>> 1. (treesit--enclosing-thing (pos thing)) - returns node or nil if no
>> enclosing parent
>> 2. (treesit--find-sibling (pos thing dir)) - return sibling node in
>> specified direction.
> 
> Makes sense. I think separating into two functions is ok. For 
> treesit--enclosing-thing, we might as well call it treesit--thing-at-point 
> ;-) Tentative plan: retire treesit—things-around, add 
> treesit--enclosing-thing (as --thing-at-point), add treesit--find-sibling (as 
> --sibling-thing), add treesit-node-enclose-p which tests whether a node 
> encloses another node.
> 
>> 
>> BTW, I've found another unexpected behavior on the same code:
>> 
>> 
>> 1. python-ts-mode
>> 
>> def premain():
>>   pa|ss
>> def main():
>>   pass
>> 2. after
>> (goto-char (treesit--navigate-thing (point) 1 'end 
>> treesit-defun-type-regexp))
>> 
>> def premain():
>>   pass
>> def main():
>>   pass|
>> 
>> cursor in the end of the second function
>> 
>> 3. but if you move cursor to the beginning of pass
>> 
>> def premain():
>>   |pass
>> def main():
>>   pass
>> 
>> 4.  after
>> (goto-char (treesit--navigate-thing (point) 1 'end 
>> treesit-defun-type-regexp))
>> 
>> def premain():
>>   pass|
>> def main():
>>   pass
>> 
>> This behavior does not affected by the fix proposed in the first message.
> 
> In the first case, treesit--navigate-thing returns a non-nil NEXT node. And 
> treesit—navigate will prioritize NEXT node over PARENT node (because it 
> assumes PARENT node always encloses NEXT node). Fixing the original problem 
> should fix this too.
> 
> Yuan

I’ve pushed to master four new functions: treesit--thing-prev, 
treesit--thing-next, treesit--thing-at, treesit-node-enclosed-p. And I updated 
other functions to use the new functions. Now your original example and the 
later ones should all work right.

Yuan