Add 'treesit-forward-comment' with 'forward-comment-function'

* lisp/treesit.el (treesit-forward-comment): New function.
(treesit-major-mode-setup): Set 'forward-comment-function' to
'treesit-forward-comment' if the 'comment' thing is defined.

* src/syntax.c (forward-comment-function): New variable.
(Fforward_comment): Call the function from 'forward-comment-function'
when it's non-nil (bug#75609).

1 files changed, 8 insertions, 0 deletions

diff --git a/src/syntax.c b/src/syntax.c
index 6ffa8a94c7f..e25618ee03d 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -2434,6 +2434,9 @@ between them, return t; otherwise return nil.  */)
   int dummy2;
   unsigned short int quit_count = 0;
 
+  if (!NILP (Vforward_comment_function))
+    return calln (Vforward_comment_function, count);
+
   CHECK_FIXNUM (count);
   count1 = XFIXNUM (count);
   stop = count1 > 0 ? ZV : BEGV;
@@ -3796,6 +3799,11 @@ In both cases, LIMIT bounds the search. */);
   DEFSYM (Qcomment_end_can_be_escaped, "comment-end-can-be-escaped");
   Fmake_variable_buffer_local (Qcomment_end_can_be_escaped);
 
+  DEFVAR_LISP ("forward-comment-function", Vforward_comment_function,
+               doc: /* If non-nil, `forward-comment' delegates to this function.
+Should take the same arguments and behave similarly to `forward-comment'.  */);
+  Vforward_comment_function = Qnil;
+
   defsubr (&Ssyntax_table_p);
   defsubr (&Ssyntax_table);
   defsubr (&Sstandard_syntax_table);