Re: Tree sitter support for C-like languages

[Yuan Fu <casouri@gmail.com>]

> On Nov 14, 2022, at 12:10 PM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> From: Yuan Fu <casouri@gmail.com>
>> Date: Mon, 14 Nov 2022 11:51:59 -0800
>> Cc: monnier@iro.umontreal.ca,
>> theo@thornhill.no,
>> emacs-devel@gnu.org
>> 
>>>> Well we update the parse tree and re-parse, but we currently don’t update the nodes created from the old tree. Keeping all nodes updated requires us to track all live nodes and update them whenever the buffer is edited.
>>> 
>>> I guess I still don't understand what exactly do you mean by "update
>>> the node".  Can you explain that in more detail?
>> 
>> My bad. So when buffer changes (insert in X, delete from X to Y), we inform tree-sitter of this change by “updating” the tree:
>> 
>>  const TSInputEdit edit =
>>    treesit_prepare_input_edit (start_byte, old_end_byte, new_end_byte);
>> 
>>  ts_tree_edit (tree, &edit);
>> 
>> Then when we re-parse, tree-sitter knows which part of the buffer has changed and needs to be re-parsed, and only parses those, hence “incremental parsing”. 
>> 
>> Tree-sitter nodes needs similar updates, so that it is in sync with the buffer text.
> 
> Doesn't the call to ts_tree_edit update those nodes?  

No.

> That is, aren't
> those nodes a part of the tree that gets updated by the ts_tree_edit
> call?

The node stores some information in itself (start_byte, end_byte, inlined data, etc), and references the tree for the rest. The information it stores needs to be updated separately.

Yuan