Cleaning the buffer-undo-list of unwanted entries

Question

When multiple-cursors is deactivated, I would like to remove from the buffer-undo-list all entries that look like this:

(apply activate-cursor-for-undo 40)

(apply deactivate-cursor-after-undo 38)

How can I remove all such entries in one fell swoop?

BACKGROUND: I am storing the buffer-undo-list and buffer-undo-tree in the desktop restore file, and I'd like to make it smaller so that Emacs will handle starting and shutting down more efficiently.

Answer 1

The following code fragment should do what you want:

(require 'cl-lib)
(setq buffer-undo-list
      (cl-remove-if (lambda (x) (and (consp x) (eq (car x) 'apply)
                     (setq x (cdr x))
                     (consp x) (memq (car x) '(activate-cursor-for-undo deactivate-cursor-after-undo))
                     (setq x (cdr x))
                     (consp x) (numberp (car x))))
            buffer-undo-list))

(Note, that this is not fully tested. Comments welcome.)