+(defun keymap--menu-item-binding (val)
+ "Return the binding part of a menu-item."
+ (cond
+ ((not (consp val)) val) ;Not a menu-item.
+ ((eq 'menu-item (car val))
+ (let* ((binding (nth 2 val))
+ (plist (nthcdr 3 val))
+ (filter (plist-get plist :filter)))
+ (if filter (funcall filter binding)
+ binding)))
+ ((and (consp (cdr val)) (stringp (cadr val)))
+ (cddr val))
+ ((stringp (car val))
+ (cdr val))
+ (t val))) ;Not a menu-item either.
+
+(defun keymap--menu-item-with-binding (item binding)
+ "Build a menu-item like ITEM but with its binding changed to BINDING."
+ (cond
+ ((not (consp item)) binding) ;Not a menu-item.
+ ((eq 'menu-item (car item))
+ (setq item (copy-sequence item))
+ (let ((tail (nthcdr 2 item)))
+ (setcar tail binding)
+ ;; Remove any potential filter.
+ (if (plist-get (cdr tail) :filter)
+ (setcdr tail (plist-put (cdr tail) :filter nil))))
+ item)
+ ((and (consp (cdr item)) (stringp (cadr item)))
+ (cons (car item) (cons (cadr item) binding)))
+ (t (cons (car item) binding))))
+
+(defun keymap--merge-bindings (val1 val2)
+ "Merge bindings VAL1 and VAL2."
+ (let ((map1 (keymap--menu-item-binding val1))
+ (map2 (keymap--menu-item-binding val2)))
+ (if (not (and (keymapp map1) (keymapp map2)))
+ ;; There's nothing to merge: val1 takes precedence.
+ val1
+ (let ((map (list 'keymap map1 map2))
+ (item (if (keymapp val1) (if (keymapp val2) nil val2) val1)))
+ (keymap--menu-item-with-binding item map)))))
+