Function: cancel-change-group

cancel-change-group is a byte-compiled function defined in subr.el.gz.

Signature

(cancel-change-group HANDLE)

Documentation

Finish a change group made with prepare-change-group (which see).

This finishes the change group by reverting all of its changes.

Probably introduced at or before Emacs version 22.1.

Source Code

;; Defined in /usr/src/emacs/lisp/subr.el.gz
(defun cancel-change-group (handle)
  "Finish a change group made with `prepare-change-group' (which see).
This finishes the change group by reverting all of its changes."
  (dolist (elt handle)
    (with-current-buffer (car elt)
      (setq elt (cdr elt))
      (save-restriction
	;; Widen buffer temporarily so if the buffer was narrowed within
	;; the body of `atomic-change-group' all changes can be undone.
	(widen)
	(let ((old-car (car-safe elt))
	      (old-cdr (cdr-safe elt))
	      ;; Use `pending-undo-list' temporarily since `undo-more' needs
	      ;; it, but restore it afterwards so as not to mess with an
	      ;; ongoing sequence of `undo's.
	      (pending-undo-list
	       ;; Use `buffer-undo-list' unconditionally (bug#39680).
	       buffer-undo-list))
          (unwind-protect
              (progn
                ;; Temporarily truncate the undo log at ELT.
                (when (consp elt)
                  (setcar elt nil) (setcdr elt nil))
                ;; Make sure there's no confusion.
                (when (and (consp elt) (not (eq elt (last pending-undo-list))))
                  (error "Undoing to some unrelated state"))
                ;; Undo it all.
                (save-excursion
                  (while (listp pending-undo-list) (undo-more 1)))
                ;; Revert the undo info to what it was when we grabbed
                ;; the state.
                (setq buffer-undo-list elt))
            ;; Reset the modified cons cell ELT to its original content.
            (when (consp elt)
              (setcar elt old-car)
              (setcdr elt old-cdr))))))))