hideshow: Rework previous changes

* lisp/progmodes/hideshow.el (hs-grok-mode-type): Improve 'hs--set-variable'.
* lisp/progmodes/python.el (python-base-mode, python-ts-mode):
Provide backward-compatibility for older versions.

2 files changed, 40 insertions, 22 deletions

diff --git a/lisp/progmodes/hideshow.el b/lisp/progmodes/hideshow.el
index 764fdb66848..c8b4e68f00f 100644
--- a/lisp/progmodes/hideshow.el
+++ b/lisp/progmodes/hideshow.el
@@ -1019,21 +1019,21 @@ Otherwise, return nil."
           (when (>= (point) q)
             (list (and hideable p) (point))))))))
 
-(defun hs--set-variable (var old-nth &optional default)
+(defun hs--set-variable (var nth &optional default)
   "Set Hideshow VAR if already not set.
 This function is meant to be used for backward compatibility with
 `hs-special-modes-alist'.
 
-OLD-NTH is a number indicating NTH element of `hs-special-modes-alist'.
+NTH must be a number indicating NTH element of
+`hs-special-modes-alist' or a function.
 
 DEFAULT is a value to use as fallback."
   (unless (local-variable-p var) ; Already set, nothing to do.
-    (if-let* (old-nth
-              (old-lookup (assoc major-mode hs-special-modes-alist)))
-        (set (make-local-variable var)
-             (if (integerp old-nth)
-                 (nth old-nth old-lookup)
-               (funcall old-nth old-lookup)))
+    (if-let* ((old-lookup (assoc major-mode hs-special-modes-alist))
+              (val (if (integerp nth)
+                       (nth nth old-lookup)
+                     (funcall nth old-lookup))))
+        (set (make-local-variable var) val)
       (when default
         (set (make-local-variable var) default)))))
 
@@ -1048,12 +1048,14 @@ If `hs-special-modes-alist' has information associated with the current
 buffer's major mode, use that.  Otherwise, guess start, end and
 `comment-start' regexps; `forward-sexp' function; and
 adjust-block-beginning function."
-  (hs--set-variable 'hs-block-start-regexp #'caadr)
-  (hs--set-variable 'hs-block-start-mdata-select #'cadadr)
+  (hs--set-variable 'hs-block-start-regexp
+                    (lambda (v) (car (ensure-list (nth 1 v)))))
+  (hs--set-variable 'hs-block-start-mdata-select
+                    (lambda (v) (cadr (ensure-list (nth 1 v)))))
   (hs--set-variable 'hs-block-end-regexp 2)
   (hs--set-variable 'hs-c-start-regexp 3
                     (string-trim-right (regexp-quote comment-start)))
-  (hs--set-variable 'hs-forward-sexp-function 4)
+  (hs--set-variable 'hs-forward-sexp-function 4 #'forward-sexp)
   (hs--set-variable 'hs-adjust-block-beginning-function 5)
   (hs--set-variable 'hs-find-block-beginning-function 6)
   (hs--set-variable 'hs-find-next-block-function 7)
diff --git a/lisp/progmodes/python.el b/lisp/progmodes/python.el
index 12557aecf4d..c4cf7ec46cf 100644
--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -7355,15 +7355,30 @@ implementations: `python-mode' and `python-ts-mode'."
                       #'python-eldoc-function))))
   (eldoc-add-command-completions "python-indent-dedent-line-backspace")
 
-  (setq-local hs-block-start-regexp python-nav-beginning-of-block-regexp)
-  ;; Use the empty string as end regexp so it doesn't default to
-  ;; "\\s)".  This way parens at end of defun are properly hidden.
-  (setq-local hs-block-end-regexp "")
-  (setq-local hs-c-start-regexp "#")
-  (setq-local hs-forward-sexp-function #'python-hideshow-forward-sexp-function)
-  (setq-local hs-find-block-beginning-function #'python-nav-beginning-of-block)
-  (setq-local hs-find-next-block-function #'python-hideshow-find-next-block)
-  (setq-local hs-looking-at-block-start-predicate #'python-info-looking-at-beginning-of-block)
+  (if (< emacs-major-version 31)
+      (dolist (mode '(python-mode python-ts-mode))
+        (add-to-list
+         'hs-special-modes-alist
+         `(,mode
+           ,python-nav-beginning-of-block-regexp
+           ;; Use the empty string as end regexp so it doesn't default to
+           ;; "\\s)".  This way parens at end of defun are properly hidden.
+           ""
+           "#"
+           python-hideshow-forward-sexp-function
+           nil
+           python-nav-beginning-of-block
+           python-hideshow-find-next-block
+           python-info-looking-at-beginning-of-block)))
+    (setq-local hs-block-start-regexp python-nav-beginning-of-block-regexp)
+    ;; Use the empty string as end regexp so it doesn't default to
+    ;; "\\s)".  This way parens at end of defun are properly hidden.
+    (setq-local hs-block-end-regexp "")
+    (setq-local hs-c-start-regexp "#")
+    (setq-local hs-forward-sexp-function #'python-hideshow-forward-sexp-function)
+    (setq-local hs-find-block-beginning-function #'python-nav-beginning-of-block)
+    (setq-local hs-find-next-block-function #'python-hideshow-find-next-block)
+    (setq-local hs-looking-at-block-start-predicate #'python-info-looking-at-beginning-of-block))
 
   (setq-local outline-regexp (python-rx (* space) block-start))
   (setq-local outline-level
@@ -7437,8 +7452,9 @@ implementations: `python-mode' and `python-ts-mode'."
     (setq-local forward-sexp-function #'treesit-forward-sexp
                 treesit-sexp-thing 'sexp)
 
-    (setq-local hs-treesit-things '(or defun sexp))
-    (setq-local hs-adjust-block-end-function #'python-ts-hs-adjust-block-end-fn)
+    (when (>= emacs-major-version 31)
+      (setq-local hs-treesit-things '(or defun sexp))
+      (setq-local hs-adjust-block-end-function #'python-ts-hs-adjust-block-end-fn))
 
     (setq-local syntax-propertize-function #'python--treesit-syntax-propertize)