bug#74963: Ambiguous treesit named and anonymous nodes in ruby-ts-mode

[Dmitry Gutov <dmitry@gutov.dev>]

Hi Juri,

On 24/12/2024 09:17, Juri Linkov wrote:
> While addition of '(and named "unless")' would be appreciated,
> I see that currently it's possible to do this by proving a predicate
> like there is 'ruby-ts--sexp-p' in
> 
>    (setq-local treesit-thing-settings
>                `((ruby
>                   (sexp ,(cons (rx
>                                 bol
>                                 (or
>                                  "class"
>                                  ...
>                                  )
>                                 eol)
>                                #'ruby-ts--sexp-p))
> 
> Then 'ruby-ts--sexp-p' could check for the named node "unless" as well.
> 
> But it seems such solution is less efficient than adding '(and named "unless")'.

Given that we're already calling a predicate every time (in 
ruby-ts-mode), we might as well add one more check. See the patch at the 
end.

Speaking of tricky examples though, here's a definition:

   module Bar
     class Foo
       def baz
       end
     end
   end

If you move point inside the keyword "module" or "class", C-M-f wouldn't 
move forward either as of the latest master. No such problem with "def".

Adding the check for "named" fixes the first two cases, but then C-M-f 
inside "def" jumps to after "baaz". Could be worked around with a 
special case, but I wonder what this difference comes from (haven't 
properly debugged yet).

diff --git a/lisp/progmodes/ruby-ts-mode.el b/lisp/progmodes/ruby-ts-mode.el
index 4ef0cb18eae..4b15c6cbf27 100644
--- a/lisp/progmodes/ruby-ts-mode.el
+++ b/lisp/progmodes/ruby-ts-mode.el
@@ -1120,6 +1120,10 @@ ruby-ts--sexp-p
        (equal (treesit-node-type (treesit-node-child node 0))
               "(")))

+(defun ruby-ts--sexp-list-p (node)
+  (when (treesit-node-check node 'named)
+    (ruby-ts--sexp-p node)))
+
  (defvar-keymap ruby-ts-mode-map
    :doc "Keymap used in Ruby mode"
    :parent prog-mode-map
@@ -1235,7 +1239,7 @@ ruby-ts-mode
                             "array"
                             "hash")
                            eol)
-                         #'ruby-ts--sexp-p))
+                         #'ruby-ts--sexp-list-p))
                   (text ,(lambda (node)
                            (or (member (treesit-node-type node)
                                        '("comment" "string_content" 
"heredoc_content"))