Could someone explain to me what the recent change in simple.el (appended
below) does?
I'm especially wondering why we turned a check for `equiv' into a check for
(listp equiv), thus allowing nil values through: the following code doesn't
seem to make uch sense when equiv is nil.
Stefan
2005-04-11 Richard M. Stallman <[EMAIL PROTECTED]>
* simple.el (undo): Record t in undo-equiv-table
for the redo record made by an undo-in-region.
Index: lisp/simple.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/simple.el,v
retrieving revision 1.708
retrieving revision 1.709
diff -u -r1.708 -r1.709
--- lisp/simple.el 7 Apr 2005 15:15:15 -0000 1.708
+++ lisp/simple.el 11 Apr 2005 18:09:45 -0000 1.709
@@ -1279,7 +1279,9 @@
(defalias 'advertised-undo 'undo)
(defconst undo-equiv-table (make-hash-table :test 'eq :weakness t)
- "Table mapping redo records to the corresponding undo one.")
+ "Table mapping redo records to the corresponding undo one.
+A redo record for undo-in-region maps to t.
+A redo record for ordinary undo maps to the following (earlier) undo.")
(defvar undo-in-region nil
"Non-nil if `pending-undo-list' is not just a tail of `buffer-undo-list'.")
@@ -1339,7 +1341,7 @@
(message (if undo-in-region
(if equiv "Redo in region!" "Undo in region!")
(if equiv "Redo!" "Undo!"))))
- (when (and equiv undo-no-redo)
+ (when (and (listp equiv) undo-no-redo)
;; The equiv entry might point to another redo record if we have done
;; undo-redo-undo-redo-... so skip to the very last equiv.
(while (let ((next (gethash equiv undo-equiv-table)))
@@ -1350,10 +1352,13 @@
(prefix-numeric-value arg)
1))
;; Record the fact that the just-generated undo records come from an
- ;; undo operation, so we can skip them later on.
+ ;; undo operation--that is, they are redo records.
+ ;; In the ordinary case (not within a region), map the redo
+ ;; record to the following undos.
;; I don't know how to do that in the undo-in-region case.
- (unless undo-in-region
- (puthash buffer-undo-list pending-undo-list undo-equiv-table))
+ (puthash buffer-undo-list
+ (if undo-in-region t pending-undo-list)
+ undo-equiv-table)
;; Don't specify a position in the undo record for the undo command.
;; Instead, undoing this should move point to where the change is.
(let ((tail buffer-undo-list)
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