Re: [WIP PATCH] Adding keys to keymaps in alphabetical order (for use with `mode-line-mode-menu')

[Jim Porter <jporterbugs@gmail.com>]

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On 6/21/2021 5:31 AM, Lars Ingebrigtsen wrote:
> Jim Porter <jporterbugs@gmail.com> writes:
> 
>> I'll look into the best way to trigger a sort just before opening the
>> menu. Ideally, we could avoid re-sorting every time (unless the list
>> has changed), but that might be more work than it's worth, given that
>> the list is unlikely to be more than a few dozen elements.
> 
> Yeah, menus are usually short, so just sorting should be fine, I think.

Attached is a patch that I think should do this. I've only tested the 
new functions with `mode-line-mode-menu', so they might not work on all 
menus (hence, I've made them private for now). It's possible these 
functions would be more broadly useful, though.

Performance-wise, the cost is negligible for the default value of 
`mode-line-mode-menu': ~10ms for the first time and 0.02ms for 
subsequent calls.

- Jim

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From f25ba15da1148ee24c70e44f3d144fdf879edb0e Mon Sep 17 00:00:00 2001
From: Jim Porter <jporterbugs@gmail.com>
Date: Tue, 22 Jun 2021 21:52:37 -0700
Subject: [PATCH] Sort the items in 'mode-line-mode-menu' before displaying the
 menu

* lisp/bindings.el (bindings--menu-item-string, bindings--sort-keymap):
New functions.
(mode-line-major-mode-keymap, mode-line-minor-mode-keymap):
Sort 'mode-line-mode-menu'.
---
 lisp/bindings.el | 37 +++++++++++++++++++++++++++++++++----
 1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/lisp/bindings.el b/lisp/bindings.el
index 4e5497cc79..f3c4f42f78 100644
--- a/lisp/bindings.el
+++ b/lisp/bindings.el
@@ -330,22 +330,51 @@ bindings--define-key
 (defvar mode-line-mode-menu (make-sparse-keymap "Minor Modes") "\
 Menu of mode operations in the mode line.")
 
+(defun bindings--menu-item-string (item)
+  "Return the menu-item string for ITEM, or nil if not a menu-item."
+  (cond
+   ((not (consp item)) nil)             ; Not a menu-item.
+   ((eq 'menu-item (car item))
+    (eval (cadr item)))
+   ((stringp (car item))
+    (car item))
+   (t nil)))                            ; Not a menu-item either.
+
+(defun bindings--sort-keymap (keymap)
+  "Sort the bindings in KEYMAP in alphabetical order.
+The order of bindings in a keymap matters only when it is used as
+a menu, so this function is not useful for non-menu keymaps."
+  (or (keymapp keymap)
+      (signal 'wrong-type-argument (list 'keymapp keymap)))
+  (let ((menu-items
+         (sort (cdr keymap)
+               (lambda (a b)
+                 (string< (bindings--menu-item-string (cdr-safe a))
+                          (bindings--menu-item-string (cdr-safe b)))))))
+    (setcdr keymap menu-items)
+    keymap))
+
 (defvar mode-line-major-mode-keymap
   (let ((map (make-sparse-keymap)))
     (bindings--define-key map [mode-line down-mouse-1]
       `(menu-item "Menu Bar" ignore
         :filter ,(lambda (_) (mouse-menu-major-mode-map))))
     (define-key map [mode-line mouse-2] 'describe-mode)
-    (define-key map [mode-line down-mouse-3] mode-line-mode-menu)
+    (bindings--define-key map [mode-line down-mouse-3]
+      `(menu-item "Menu Bar" ,mode-line-mode-menu
+        :filter bindings--sort-keymap))
     map) "\
 Keymap to display on major mode.")
 
 (defvar mode-line-minor-mode-keymap
-  (let ((map (make-sparse-keymap)))
+  (let ((map (make-sparse-keymap))
+        (mode-menu-binding
+         `(menu-item "Menu Bar" ,mode-line-mode-menu
+           :filter bindings--sort-keymap)))
     (define-key map [mode-line down-mouse-1] 'mouse-minor-mode-menu)
     (define-key map [mode-line mouse-2] 'mode-line-minor-mode-help)
-    (define-key map [mode-line down-mouse-3] mode-line-mode-menu)
-    (define-key map [header-line down-mouse-3] mode-line-mode-menu)
+    (define-key map [mode-line down-mouse-3] mode-menu-binding)
+    (define-key map [header-line down-mouse-3] mode-menu-binding)
     map) "\
 Keymap to display on minor modes.")
 
-- 
2.25.1