diff options
Diffstat (limited to 'lisp/simple.el')
| -rw-r--r-- | lisp/simple.el | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/lisp/simple.el b/lisp/simple.el index a757876328..51c9100d2c 100644 --- a/lisp/simple.el +++ b/lisp/simple.el @@ -2958,6 +2958,41 @@ behavior." (undo-auto--boundary-ensure-timer)) ;; End auto-boundary section +(defun undo-amalgamate-change-group (handle) + "Amalgamate changes in change-group since HANDLE. +Remove all undo boundaries between the state of HANDLE and now. +HANDLE is as returned by `prepare-change-group'." + (dolist (elt handle) + (with-current-buffer (car elt) + (setq elt (cdr elt)) + (when (consp buffer-undo-list) + (let ((old-car (car-safe elt)) + (old-cdr (cdr-safe elt))) + (unwind-protect + (progn + ;; Temporarily truncate the undo log at ELT. + (when (consp elt) + (setcar elt t) (setcdr elt nil)) + (when + (or (null elt) ;The undo-log was empty. + ;; `elt' is still in the log: normal case. + (eq elt (last buffer-undo-list)) + ;; `elt' is not in the log any more, but that's because + ;; the log is "all new", so we should remove all + ;; boundaries from it. + (not (eq (last buffer-undo-list) (last old-cdr)))) + (cl-callf (lambda (x) (delq nil x)) + (if (car buffer-undo-list) + buffer-undo-list + ;; Preserve the undo-boundaries at either ends of the + ;; change-groups. + (cdr buffer-undo-list))))) + ;; Reset the modified cons cell ELT to its original content. + (when (consp elt) + (setcar elt old-car) + (setcdr elt old-cdr)))))))) + + (defcustom undo-ask-before-discard nil "If non-nil ask about discarding undo info for the current command. Normally, Emacs discards the undo info for the current command if |