Subject: [PATCH] Tree-sitter: fix an issue when searching subtree backward

From: Denis Zubarev <[email-masked]>
Date: Sun, 12 Nov 2023 02:38:33 +0300

Tags: patch

Steps to reproduce the issue:
1. emacs -Q
2. M-x find-file /tmp/t.py
3. paste to the buffer
 
Temp(1, 2) 
 
4. M-x python-ts-mode
5. Call search-subtree with backward flag
   M-x eval-expression (treesit-search-subtree
               (treesit--thing-at (point) "call")
               (lambda (n) (equal (treesit-node-type n ) "integer"))
               t)
It should return the second int node (#<treesit-node integer in 9-10>), but it returns nil.

I fixed it in treesit_traverse_child_helper.
Do not call treesit_traverse_sibling_helper when the named node is
required and the last child is the named node.
Otherwise treesit_traverse_sibling_helper will move cursor to the
previous sibling and the last node will be skipped.
I've added test for this bug.

In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.33, cairo version 1.16.0) of 2023-11-12 built on NUC-here
Repository revision: 400a71b8f2c5a49dce4f542adfd2fdb59eb34243
Repository branch: search-subtree-bacward-fix
Windowing system distributor 'The X.Org Foundation', version 11.0.12101004
System Description: Ubuntu 22.04.3 LTS

Configured using:
 'configure --with-modules --with-native-compilation=aot
 --with-imagemagick --with-json --with-tree-sitter --with-xft'

>From 88e913940cdd3c82afbdf2ad6520e1a1b9c2797b Mon Sep 17 00:00:00 2001
From: Denis Zubarev <[email-masked]>
Date: Sun, 12 Nov 2023 01:42:42 +0300
Subject: [PATCH] Fix an issue when searching subtree backward

* src/treesit.c (treesit_traverse_child_helper):
Do not call treesit_traverse_sibling_helper when the named node is
required and the last child is the named node.
Otherwise treesit_traverse_sibling_helper will move cursor to the
previous sibling and last node will be skipped.
* test/src/treesit-tests.el (treesit-search-subtree-forward-1):
(treesit-search-subtree-backward-1):
Add tests
---
 src/treesit.c             |  4 ++--
 test/src/treesit-tests.el | 30 ++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/src/treesit.c b/src/treesit.c
index 69b59fca11..4dcad751f4 100644
--- a/src/treesit.c
+++ b/src/treesit.c
@@ -3247,9 +3247,9 @@ treesit_traverse_child_helper (TSTreeCursor *cursor,
       /* First go to the last child.  */
       while (ts_tree_cursor_goto_next_sibling (cursor));
 
-      if (!named)
+      if (!named || (named && ts_node_is_named (ts_tree_cursor_current_node(cursor))))
 	return true;
-      /* Else named... */
+      /* Else named is required and last child is not named node */
       if (treesit_traverse_sibling_helper(cursor, false, true))
 	return true;
       else
diff --git a/test/src/treesit-tests.el b/test/src/treesit-tests.el
index 791e902bd0..c9b15c618c 100644
--- a/test/src/treesit-tests.el
+++ b/test/src/treesit-tests.el
@@ -1167,6 +1167,36 @@ treesit-defun-navigation-top-level
    treesit--ert-defun-navigation-top-level-master
    'top-level))
 
+(ert-deftest treesit-search-subtree-forward-1 ()
+  "Test search subtree forward."
+  (skip-unless (treesit-language-available-p 'python))
+  (require 'python)
+  (python-ts-mode)
+  (insert "Temp(1, 2)")
+  (goto-char (point-min))
+  (let ((node (treesit-search-subtree
+               (treesit--thing-at (point) "call")
+               (lambda (n) (equal (treesit-node-type n ) "integer")))))
+
+    (should node)
+    (should (equal (treesit-node-text node) "1"))))
+
+(ert-deftest treesit-search-subtree-backward-1 ()
+  "Test search subtree with backward=t."
+  (skip-unless (treesit-language-available-p 'python))
+  (require 'python)
+  (python-ts-mode)
+  (insert "Temp(1, 2)")
+  (goto-char (point-min))
+  (let ((node (treesit-search-subtree
+               (treesit--thing-at (point) "call")
+               (lambda (n) (equal (treesit-node-type n ) "integer"))
+               t)))
+
+    (should node)
+    (should (equal (treesit-node-text node) "2"))))
+
+
 ;; TODO
 ;; - Functions in treesit.el
 ;; - treesit-load-name-override-list
-- 
2.34.1