Re: Tree-sitter navigation time grows as sqrt(line-number)

[Dmitry Gutov <dmitry@gutov.dev>]

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On 17/08/2023 17:36, Dmitry Gutov wrote:
> On 17/08/2023 17:25, Dmitry Gutov wrote:
>> On 17/08/2023 17:08, Felix wrote:
>>> Hi,
>>>
>>> I tried that patch, and it crashes emacs whenever i try to scroll inside
>>> a tree-sitter managed buffer.
>>>
>>> GNU Emacs 30.0.50 (build 22, x86_64-pc-linux-gnu, GTK+ Version 
>>> 3.24.38, cairo version 1.17.8) of 2023-08-17
>>>
>>> compiled with pgtk running on wayland.
>>
>> Thanks for testing. Does that happen in any ts mode, or some 
>> particular ones?
>>
>> If you run Emacs from the terminal, could you post the error backtrace?
>>
>> (Please keep emacs-devel in Cc).
> 
> For my part, I don't see it crash when scrolling (in ruby-ts-mdoe or 
> js-ts-mode, including larges files), but the test scenario by JD does 
> make it crash.
> 
> When running under GDB, the backtrace simply looks like this:
> 
> #0  0x00007ffff63bf93d in ts_tree_root_node (self=0x0) at lib/src/tree.c:36
> #1  0x00007ffff63a54e5 in ts_node_parent (self=...) at lib/src/node.c:462
> #2  0x00005555557f0d17 in Ftreesit_node_parent 
> (node=XIL(0x5555574908c5)) at treesit.c:1906
> #3  0x000055555576f62b in eval_sub (form=<optimized out>) at eval.c:2511
> #4  0x000055555576f987 in Fsetq (args=<optimized out>) at eval.c:483
> #5  0x000055555576f368 in eval_sub (form=<optimized out>) at eval.c:2462
> #6  0x000055555576ff75 in Fprogn (body=XIL(0)) at eval.c:436
> ...

Try this one.

I've read the tree-sitter docs a bit more, and also dropped the "else" 
case because it was unreachable anyway. I doesn't crash anymore here.

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diff --git a/src/treesit.c b/src/treesit.c
index 1f694e47201..46fbacaefe3 100644
--- a/src/treesit.c
+++ b/src/treesit.c
@@ -52,6 +52,7 @@ Copyright (C) 2021-2023 Free Software Foundation, Inc.
 #undef ts_node_named_descendant_for_byte_range
 #undef ts_node_next_named_sibling
 #undef ts_node_next_sibling
+#undef ts_node_parent
 #undef ts_node_prev_named_sibling
 #undef ts_node_prev_sibling
 #undef ts_node_start_byte
@@ -1895,21 +1896,15 @@ DEFUN ("treesit-node-parent",
   treesit_check_node (node);
   treesit_initialize ();
 
-  Lisp_Object return_value = Qnil;
-
   TSNode treesit_node = XTS_NODE (node)->node;
   Lisp_Object parser = XTS_NODE (node)->parser;
-  TSTreeCursor cursor;
-  if (!treesit_cursor_helper (&cursor, treesit_node, parser))
-    return return_value;
 
-  if (ts_tree_cursor_goto_parent (&cursor))
-  {
-    TSNode parent = ts_tree_cursor_current_node (&cursor);
-    return_value = make_treesit_node (parser, parent);
-  }
-  ts_tree_cursor_delete (&cursor);
-  return return_value;
+  TSNode parent = ts_node_parent (treesit_node);
+
+  if (ts_node_is_null (parent))
+    return Qnil;
+
+  return make_treesit_node (parser, parent);
 }
 
 DEFUN ("treesit-node-child",