Improve treesit-forward-sexp behavior for leaf nodes (bug#68899)

treesit-forward-sexp uses treesit--navigate-thing with 'restricted'
tactic.  In this tactic we don't move over the parent thing.  However,
this makes forward-sexp useless for symbols when point is in the
symbol rather than at the beginning of it: in that case, the symbol is
considered parent and treesit-forward-sexp won't move to the end of
it.

To solve that, we allow to move across the parent even in 'restricted'
mode if the parent is a leaf thing.

Here, "leaf thing" is defined as "doesn't have any child 'thing'
inside it".

* lisp/treesit.el (treesit--navigate-thing): Move over parent in
'restricted' tactic if the parent is a leaf thing.

(cherry picked from commit 9dbbf93a4a08f71cf5f2278ec2a22a722fe0e0f7)

diff --git a/lisp/treesit.el b/lisp/treesit.el
index fab2ddd88e6bfa020dd6fa743ace3917d866dca7..93b6b56534da28cd05f7d42e90c766f5e97e6b41 100644 (file)
--- a/lisp/treesit.el
+++ b/lisp/treesit.el
@@ -2662,9 +2662,17 @@ function is called recursively."
             (setq parent (treesit-node-top-level parent thing t)
                   prev nil
                   next nil))
-          ;; If TACTIC is `restricted', the implementation is very simple.
+          ;; If TACTIC is `restricted', the implementation is simple.
+          ;; In principle we don't go to parent's beg/end for
+          ;; `restricted' tactic, but if the parent is a "leaf thing"
+          ;; (doesn't have any child "thing" inside it), then we can
+          ;; move to the beg/end of it (bug#68899).
           (if (eq tactic 'restricted)
-              (setq pos (funcall advance (if (> arg 0) next prev)))
+              (setq pos (funcall
+                         advance
+                         (cond ((and (null next) (null prev)) parent)
+                               ((> arg 0) next)
+                               (t prev))))
             ;; For `nested', it's a bit more work:
             ;; Move...
             (if (> arg 0)