Update years in copyright notice; nfc.
[bpt/emacs.git] / lisp / winner.el
dissimilarity index 75%
index ad6ae43..de0dcde 100644 (file)
-;;; winner.el  --- Restore window configuration (or switch buffer)
-
-;; Copyright (C) 1997 Free Software Foundation. Inc.
-
-;; Author: Ivar Rummelhoff <ivarr@ifi.uio.no>
-;; Maintainer: Ivar Rummelhoff <ivarr@ifi.uio.no>
-;; Created: 27 Feb 1997
-;; Keywords: extensions, windows
-
-;; This file is part of GNU Emacs.
-
-;; GNU Emacs is free software; you can redistribute it and/or modify
-;; it under the terms of the GNU General Public License as published by
-;; the Free Software Foundation; either version 2, or (at your option)
-;; any later version.
-
-;; GNU Emacs is distributed in the hope that it will be useful,
-;; but WITHOUT ANY WARRANTY; without even the implied warranty of
-;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-;; GNU General Public License for more details.
-
-;; You should have received a copy of the GNU General Public License
-;; along with GNU Emacs; see the file COPYING.  If not, write to the
-;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-;; Boston, MA 02111-1307, USA.
-
-;;; Commentary:
-
-;; Winner mode is a global minor mode that when turned on records
-;; changes in window configuration.  This way the changes can be
-;; "undone" using the function `winner-undo'.  By default this one is
-;; bound to the key sequence ctrl-x left.  If you change your mind
-;; (while undoing), you can press ctrl-x right (calling
-;; `winner-redo').  Unlike the normal undo, you may have to skip
-;; through several identical window configurations in order to find
-;; the one you want.  This is a bug due to some techical limitations
-;; in Emacs and can maybe be fixed in the future.
-;; 
-;; In addition to this I have added `winner-switch' which is a program
-;; that switches to other buffers without disturbing Winner mode.  If
-;; you bind this command to a key sequence, you may step through all
-;; your buffers (except the ones mentioned in `winner-skip-buffers' or
-;; matched by `winner-skip-regexps').  With a numeric prefix argument
-;; skip several buffers at a time.
-
-;;; Code:
-
-(eval-when-compile (require 'cl))
-(require 'ring)
-
-(defvar winner-dont-bind-my-keys nil
-  "If non-nil: Do not use `winner-mode-map' in Winner mode.")
-
-(defvar winner-ring-size 100
-  "Maximum number of stored window configurations per frame.")
-
-(defvar winner-skip-buffers
-  '("*Messages*",
-    "*Compile-Log*",
-    ".newsrc-dribble",
-    "*Completions*",
-    "*Buffer list*")
-  "Exclude these buffer names from any \(Winner switch\) list of buffers.")
-
-(defvar winner-skip-regexps '("^ ")
-  "Winner excludes buffers with names matching any of these regexps.
-They are not included in any Winner mode list of buffers.
-
-By default `winner-skip-regexps' is set to \(\"^ \"\),
-which excludes \"invisible buffers\".")
-
-(defvar winner-ring-alist nil)
-
-(defsubst winner-ring (frame)
-  (or (cdr (assq frame winner-ring-alist))
-      (progn
-       (push (cons frame (make-ring winner-ring-size))
-             winner-ring-alist)
-       (cdar winner-ring-alist))))
-
-(defvar winner-modified-list nil)
-
-(defun winner-change-fun ()
-  (pushnew (selected-frame) winner-modified-list))
-
-(defun winner-save-new-configurations ()
-  (while winner-modified-list
-    (ring-insert
-     (winner-ring (car winner-modified-list))
-     (current-window-configuration (pop winner-modified-list)))))
-
-(defun winner-set (conf)
-  (set-window-configuration conf)
-  (if (eq (selected-window) (minibuffer-window))
-      (other-window 1)))
-
-
-;;; Winner mode  (a minor mode)
-
-(defvar winner-mode-hook nil
-  "Functions to run whenever Winner mode is turned on.")
-
-(defvar winner-mode-leave-hook nil
-  "Functions to run whenever Winner mode is turned off.")
-
-(defvar winner-mode nil) ; mode variable
-(defvar winner-mode-map nil "Keymap for Winner mode.")
-
-(defun winner-mode (&optional arg)
-  "Toggle Winner mode.
-With arg, turn Winner mode on if and only if arg is positive."
-  (interactive "P")
-  (let ((on-p (if arg (> (prefix-numeric-value arg) 0)
-               (not winner-mode))))
-    (cond
-     ;; Turn mode on
-     (on-p 
-      (setq winner-mode t)
-      (add-hook 'window-configuration-change-hook 'winner-change-fun)
-      (add-hook 'post-command-hook 'winner-save-new-configurations)
-      (setq winner-modified-list (frame-list))
-      (winner-save-new-configurations)
-      (run-hooks 'winner-mode-hook))
-     ;; Turn mode off
-     (winner-mode
-      (setq winner-mode nil)
-      (run-hooks 'winner-mode-leave-hook)))
-    (force-mode-line-update)))
-
-;; Inspired by undo (simple.el)
-(defun winner-undo (arg)
-  "Switch back to an earlier window configuration saved by Winner mode.
-In other words, \"undo\" changes in window configuration."
-  (interactive "p")
-  (cond
-   ((not winner-mode) (error "Winner mode is turned off"))
-   ((eq (selected-window) (minibuffer-window))
-    (error "No winner undo from minibuffer."))
-   (t (setq this-command t)
-      (if (eq last-command 'winner-undo)
-         ;; This was no new window configuration after all.
-         (ring-remove winner-pending-undo-ring 0)
-       (setq winner-pending-undo-ring (winner-ring (selected-frame)))
-       (setq winner-undo-counter 0))
-      (winner-undo-more (or arg 1))
-      (message "Winner undo (%d)!" winner-undo-counter)
-      (setq this-command 'winner-undo))))
-
-(defvar winner-pending-undo-ring nil)
-
-(defvar winner-undo-counter nil)
-
-(defun winner-undo-more (count)
-  "Undo N window configuration changes beyond what was already undone.
-Call `winner-undo-start' to get ready to undo recent changes,
-then call `winner-undo-more' one or more times to undo them."
-  (let ((len (ring-length winner-pending-undo-ring)))
-    (incf winner-undo-counter count)
-    (if (>= winner-undo-counter len)
-       (error "No further window configuration undo information")
-      (winner-set
-       (ring-ref winner-pending-undo-ring
-                winner-undo-counter)))))
-
-(defun winner-redo ()
-  "Restore a more recent window configuration saved by Winner mode."
-  (interactive)
-  (cond
-   ((eq last-command 'winner-undo)
-    (ring-remove winner-pending-undo-ring 0)
-    (winner-set
-     (ring-remove winner-pending-undo-ring 0))
-    (or (eq (selected-window) (minibuffer-window))
-       (message "Winner undid undo!")))
-   (t (error "Previous command was not a winner-undo"))))
-
-;;; Winner switch
-
-(defun winner-switch-buffer-list ()
-  (loop for buf in (buffer-list)
-       for name = (buffer-name buf)
-       unless (or (eq (current-buffer) buf)
-                  (member name winner-skip-buffers)
-                  (loop for regexp in winner-skip-regexps
-                        if (string-match regexp name) return t
-                        finally return nil))
-       collect name))
-  
-(defvar winner-switch-list nil)
-
-(defun winner-switch (count)
-  "Step through your buffers without disturbing `winner-mode'.
-`winner-switch' does not consider buffers mentioned in the list
-`winner-skip-buffers' or matched by `winner-skip-regexps'."
-  (interactive "p")
-  (decf count)
-  (setq this-command t)
-  (cond
-   ((eq last-command 'winner-switch)
-    (if winner-mode (ring-remove (winner-ring (selected-frame)) 0))
-    (bury-buffer (current-buffer))
-    (mapcar 'bury-buffer winner-switch-list))
-   (t (setq winner-switch-list (winner-switch-buffer-list))))
-  (setq winner-switch-list (nthcdr count winner-switch-list))
-  (or winner-switch-list
-      (setq winner-switch-list (winner-switch-buffer-list))
-      (error "No more buffers"))
-  (switch-to-buffer (pop winner-switch-list))
-  (message (concat "Winner: [%s] "
-                  (mapconcat 'identity winner-switch-list " "))
-          (buffer-name))
-  (setq this-command 'winner-switch))
-
-;;;; To be evaluated when the package is loaded:
-
-(unless winner-mode-map
-  (setq winner-mode-map (make-sparse-keymap))
-  (define-key winner-mode-map [?\C-x left]  'winner-undo)
-  (define-key winner-mode-map [?\C-x right] 'winner-redo))
-
-(unless (or (assq 'winner-mode minor-mode-map-alist)
-           winner-dont-bind-my-keys)
-  (push (cons 'winner-mode winner-mode-map)
-       minor-mode-map-alist))
-
-(unless (assq 'winner-mode minor-mode-alist)
-  (push '(winner-mode " Win") minor-mode-alist))
-
-(provide 'winner)
-
-;;; winner.el ends here
+;;; winner.el --- Restore old window configurations
+
+;; Copyright (C) 1997, 1998, 2001, 2002, 2003, 2004,
+;;   2005, 2006 Free Software Foundation. Inc.
+
+;; Author: Ivar Rummelhoff <ivarru@math.uio.no>
+;; Created: 27 Feb 1997
+;; Time-stamp: <2006-02-06 15:13:57 ttn>
+;; Keywords: convenience frames
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 2, or (at your option)
+;; any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs; see the file COPYING.  If not, write to the
+;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+;; Boston, MA 02110-1301, USA.
+
+;;; Commentary:
+
+;; Winner mode is a global minor mode that records the changes in the
+;; window configuration (i.e. how the frames are partitioned into
+;; windows) so that the changes can be "undone" using the command
+;; `winner-undo'.  By default this one is bound to the key sequence
+;; ctrl-c left.  If you change your mind (while undoing), you can
+;; press ctrl-c right (calling `winner-redo').  Even though it uses
+;; some features of Emacs20.3, winner.el should also work with
+;; Emacs19.34 and XEmacs20, provided that the installed version of
+;; custom is not obsolete.
+
+;; Winner mode was improved August 1998.
+;; Further improvements February 2002.
+
+;;; Code:
+
+(eval-when-compile
+  (require 'cl))
+
+
+(defmacro winner-active-region ()
+  (if (fboundp 'region-active-p)
+      '(region-active-p)
+    'mark-active))
+
+(defsetf winner-active-region () (store)
+  (if (fboundp 'zmacs-activate-region)
+      `(if ,store (zmacs-activate-region)
+        (zmacs-deactivate-region))
+    `(setq mark-active ,store)))
+
+(defalias 'winner-edges
+  (if (featurep 'xemacs) 'window-pixel-edges 'window-edges))
+(defalias 'winner-window-list
+  (if (featurep 'xemacs)
+      (lambda () (delq (minibuffer-window) (window-list nil 0)))
+    (lambda () (window-list nil 0))))
+
+(require 'ring)
+
+(unless (fboundp 'defgroup)
+  (defmacro defgroup (&rest rest)))
+
+(defgroup winner nil
+  "Restoring window configurations."
+  :group 'windows)
+
+(unless (fboundp 'defcustom)
+  (defmacro defcustom (symbol &optional initvalue docs &rest rest)
+    (list 'defvar symbol initvalue docs)))
+
+;;;###autoload
+(defcustom winner-mode nil
+  "Toggle Winner mode.
+Setting this variable directly does not take effect;
+use either \\[customize] or the function `winner-mode'."
+  :set #'(lambda (symbol value) (funcall symbol (or value 0)))
+  :initialize 'custom-initialize-default
+  :type    'boolean
+  :group   'winner
+  :require 'winner)
+
+(defcustom winner-dont-bind-my-keys nil
+  "If non-nil: Do not use `winner-mode-map' in Winner mode."
+  :type  'boolean
+  :group 'winner)
+
+(defcustom winner-ring-size 200
+  "Maximum number of stored window configurations per frame."
+  :type  'integer
+  :group 'winner)
+
+(defcustom winner-boring-buffers '("*Completions*")
+  "`winner-undo' will not restore windows displaying any of these buffers.
+You may want to include buffer names such as *Help*, *Apropos*,
+*Buffer List*, *info* and *Compile-Log*."
+  :type '(repeat string)
+  :group 'winner)
+
+
+
+
+\f
+;;;; Saving old configurations (internal variables and subroutines)
+
+
+;;; Current configuration
+
+;; List the windows according to their edges.
+(defun winner-sorted-window-list ()
+  (sort (winner-window-list)
+        (lambda (x y)
+          (loop for a in (winner-edges x)
+                for b in (winner-edges y)
+                while (= a b)
+                finally return (< a b)))))
+
+(defun winner-win-data ()
+  ;; Essential properties of the windows in the selected frame.
+  (loop for win in (winner-sorted-window-list)
+        collect (cons (winner-edges win) (window-buffer win))))
+
+;; This variable is updated with the current window configuration
+;; every time it changes.
+(defvar winner-currents nil)
+
+;; The current configuration (+ the buffers involved).
+(defsubst winner-conf ()
+  (cons (current-window-configuration)
+        (winner-win-data)))
+
+
+;; Save current configuration.
+;; (Called below by `winner-save-old-configurations').
+(defun winner-remember ()
+  (let ((entry (assq (selected-frame) winner-currents)))
+    (if entry (setcdr entry (winner-conf))
+      (push (cons (selected-frame) (winner-conf))
+           winner-currents))))
+
+;; Consult `winner-currents'.
+(defun winner-configuration (&optional frame)
+  (or (cdr (assq (or frame (selected-frame)) winner-currents))
+      (letf (((selected-frame) frame))
+       (winner-conf))))
+
+
+
+;;; Saved configurations
+
+;; This variable contains the window cofiguration rings.
+;; The key in this alist is the frame.
+(defvar winner-ring-alist nil)
+
+;; Find the right ring.  If it does not exist, create one.
+(defsubst winner-ring (frame)
+  (or (cdr (assq frame winner-ring-alist))
+      (let ((ring (make-ring winner-ring-size)))
+        (ring-insert ring (winner-configuration frame))
+        (push (cons frame ring) winner-ring-alist)
+        ring)))
+
+\f
+;; If the same command is called several times in a row,
+;; we only save one window configuration.
+(defvar winner-last-command nil)
+
+;; Frames affected by the previous command.
+(defvar winner-last-frames nil)
+
+
+(defsubst winner-equal (a b)
+  "Check whether two Winner configurations (as produced by
+`winner-conf') are equal."
+  (equal (cdr a) (cdr b)))
+
+
+;; Save the current window configuration, if it has changed.
+;; If so return frame, otherwise return nil.
+(defun winner-insert-if-new (frame)
+  (unless (or (memq frame winner-last-frames)
+             (eq this-command 'winner-redo))
+    (let ((conf (winner-configuration frame))
+         (ring (winner-ring frame)))
+      (when (and (not (ring-empty-p ring))
+                (winner-equal conf (ring-ref ring 0)))
+        ;; When the previous configuration was very similar,
+        ;; keep only the latest.
+       (ring-remove ring 0))
+      (ring-insert ring conf)
+      (push frame winner-last-frames)
+      frame)))
+
+
+
+;;; Hooks
+
+;; Frames affected by the current command.
+(defvar winner-modified-list nil)
+
+;; Called whenever the window configuration changes
+;; (a `window-configuration-change-hook').
+(defun winner-change-fun ()
+  (unless (or (memq (selected-frame) winner-modified-list)
+              (/= 0 (minibuffer-depth)))
+    (push (selected-frame) winner-modified-list)))
+
+;; A `post-command-hook' for emacsen with
+;; `window-configuration-change-hook'.
+(defun winner-save-old-configurations ()
+  (when (zerop (minibuffer-depth))
+    (unless (eq this-command winner-last-command)
+      (setq winner-last-frames nil)
+      (setq winner-last-command this-command))
+    (dolist (frame winner-modified-list)
+      (winner-insert-if-new frame))
+    (setq winner-modified-list nil)
+    (winner-remember)))
+
+;; A `minibuffer-setup-hook'.
+(defun winner-save-unconditionally ()
+  (unless (eq this-command winner-last-command)
+    (setq winner-last-frames nil)
+    (setq winner-last-command this-command))
+  (winner-insert-if-new (selected-frame))
+  (winner-remember))
+
+;; A `post-command-hook' for other emacsen.
+;; Also called by `winner-undo' before "undoing".
+(defun winner-save-conditionally ()
+  (when (zerop (minibuffer-depth))
+    (winner-save-unconditionally)))
+
+
+
+\f
+;;;; Restoring configurations
+
+;; Works almost as `set-window-configuration',
+;; but does not change the contents or the size of the minibuffer,
+;; and tries to preserve the selected window.
+(defun winner-set-conf (winconf)
+  (let* ((miniwin  (minibuffer-window))
+         (chosen   (selected-window))
+         (minisize (window-height miniwin)))
+    (letf (((window-buffer miniwin))
+           ((window-point  miniwin)))
+      (set-window-configuration winconf))
+    (cond
+     ((window-live-p chosen) (select-window chosen))
+     ((window-minibuffer-p (selected-window))
+      (other-window 1)))
+    (when (/= minisize (window-height miniwin))
+      (letf (((selected-window) miniwin) )
+        (setf (window-height) minisize)))))
+
+
+
+(defvar winner-point-alist nil)
+;; `set-window-configuration' restores old points and marks.  This is
+;; not what we want, so we make a list of the "real" (i.e. new) points
+;; and marks before undoing window configurations.
+;;
+;; Format of entries: (buffer (mark . mark-active) (window . point) ..)
+
+(defun winner-make-point-alist ()
+  (letf (((current-buffer)))
+    (loop with alist
+         for win in (winner-window-list)
+         for entry =
+          (or (assq (window-buffer win) alist)
+              (car (push (list (set-buffer (window-buffer win))
+                               (cons (mark t) (winner-active-region)))
+                         alist)))
+         do (push (cons win (window-point win))
+                   (cddr entry))
+         finally return alist)))
+
+(defun winner-get-point (buf win)
+  ;; Consult (and possibly extend) `winner-point-alist'.
+  ;; Returns nil iff buf no longer exists.
+  (when (buffer-name buf)
+    (let ((entry (assq buf winner-point-alist)))
+      (cond
+       (entry
+       (or (cdr (assq win (cddr entry)))
+           (cdr (assq nil (cddr entry)))
+           (letf (((current-buffer) buf))
+             (push (cons nil (point)) (cddr entry))
+             (point))))
+       (t (letf (((current-buffer) buf))
+           (push (list buf
+                       (cons (mark t) (winner-active-region))
+                       (cons nil (point)))
+                 winner-point-alist)
+           (point)))))))
+
+\f
+;; Make sure point does not end up in the minibuffer and delete
+;; windows displaying dead or boring buffers
+;; (c.f. `winner-boring-buffers').  Return nil iff all the windows
+;; should be deleted.  Preserve correct points and marks.
+(defun winner-set (conf)
+  ;; For the format of `conf', see `winner-conf'.
+  (let* ((buffers nil)
+        (alive
+          ;; Possibly update `winner-point-alist'
+         (loop for buf in (mapcar 'cdr (cdr conf))
+               for pos = (winner-get-point buf nil)
+               if (and pos (not (memq buf buffers)))
+               do (push buf buffers)
+               collect pos)))
+    (winner-set-conf (car conf))
+    (let (xwins)                        ; to be deleted
+
+      ;; Restore points
+      (dolist (win (winner-sorted-window-list))
+        (unless (and (pop alive)
+                     (setf (window-point win)
+                           (winner-get-point (window-buffer win) win))
+                     (not (member (buffer-name (window-buffer win))
+                                  winner-boring-buffers)))
+          (push win xwins)))            ; delete this window
+
+      ;; Restore marks
+      (letf (((current-buffer)))
+       (loop for buf in buffers
+             for entry = (cadr (assq buf winner-point-alist))
+             do (progn (set-buffer buf)
+                       (set-mark (car entry))
+                       (setf (winner-active-region) (cdr entry)))))
+      ;; Delete windows, whose buffers are dead or boring.
+      ;; Return t if this is still a possible configuration.
+      (or (null xwins)
+         (progn
+            (mapc 'delete-window (cdr xwins)) ; delete all but one
+            (unless (one-window-p t)
+              (delete-window (car xwins))
+              t))))))
+
+
+
+;;;; Winner mode  (a minor mode)
+
+(defcustom winner-mode-hook nil
+  "Functions to run whenever Winner mode is turned on."
+  :type 'hook
+  :group 'winner)
+
+(defcustom winner-mode-leave-hook nil
+  "Functions to run whenever Winner mode is turned off."
+  :type 'hook
+  :group 'winner)
+
+(defvar winner-mode-map
+  (let ((map (make-sparse-keymap)))
+    (define-key map [(control c) left] 'winner-undo)
+    (define-key map [(control c) right] 'winner-redo)
+    map)
+  "Keymap for Winner mode.")
+
+;; Check if `window-configuration-change-hook' is working.
+(defun winner-hook-installed-p ()
+  (save-window-excursion
+    (let ((winner-var nil)
+         (window-configuration-change-hook
+          '((lambda () (setq winner-var t)))))
+      (split-window)
+      winner-var)))
+
+\f
+;;;###autoload
+(defun winner-mode (&optional arg)
+  "Toggle Winner mode.
+With arg, turn Winner mode on if and only if arg is positive."
+  (interactive "P")
+  (let ((on-p (if arg (> (prefix-numeric-value arg) 0)
+               (not winner-mode))))
+    (cond
+     ;; Turn mode on
+     (on-p
+      (setq winner-mode t)
+      (cond
+       ((winner-hook-installed-p)
+       (add-hook 'window-configuration-change-hook 'winner-change-fun)
+      (add-hook 'post-command-hook 'winner-save-old-configurations))
+       (t (add-hook 'post-command-hook 'winner-save-conditionally)))
+      (add-hook 'minibuffer-setup-hook 'winner-save-unconditionally)
+      (setq winner-modified-list (frame-list))
+      (winner-save-old-configurations)
+      (run-hooks 'winner-mode-hook)
+      (when (interactive-p) (message "Winner mode enabled")))
+     ;; Turn mode off
+     (winner-mode
+      (setq winner-mode nil)
+      (remove-hook 'window-configuration-change-hook 'winner-change-fun)
+      (remove-hook 'post-command-hook 'winner-save-old-configurations)
+      (remove-hook 'post-command-hook 'winner-save-conditionally)
+      (remove-hook 'minibuffer-setup-hook 'winner-save-unconditionally)
+      (run-hooks 'winner-mode-leave-hook)
+      (when (interactive-p) (message "Winner mode disabled"))))))
+
+;; Inspired by undo (simple.el)
+
+(defvar winner-undo-frame nil)
+
+(defvar winner-pending-undo-ring nil
+  "The ring currently used by `winner-undo'.")
+(defvar winner-undo-counter nil)
+(defvar winner-undone-data  nil) ; There confs have been passed.
+
+(defun winner-undo ()
+  "Switch back to an earlier window configuration saved by Winner mode.
+In other words, \"undo\" changes in window configuration."
+  (interactive)
+  (cond
+   ((not winner-mode) (error "Winner mode is turned off"))
+   (t (unless (and (eq last-command 'winner-undo)
+                  (eq winner-undo-frame (selected-frame)))
+       (winner-save-conditionally)     ; current configuration->stack
+       (setq winner-undo-frame (selected-frame))
+       (setq winner-point-alist (winner-make-point-alist))
+       (setq winner-pending-undo-ring (winner-ring (selected-frame)))
+       (setq winner-undo-counter 0)
+       (setq winner-undone-data (list (winner-win-data))))
+      (incf winner-undo-counter)       ; starting at 1
+      (when (and (winner-undo-this)
+                (not (window-minibuffer-p (selected-window))))
+       (message "Winner undo (%d / %d)"
+                winner-undo-counter
+                (1- (ring-length winner-pending-undo-ring)))))))
+
+
+
+\f
+(defun winner-undo-this ()             ; The heart of winner undo.
+  (loop
+   (cond
+    ((>= winner-undo-counter (ring-length winner-pending-undo-ring))
+     (message "No further window configuration undo information")
+     (return nil))
+
+    ((and                              ; If possible configuration
+      (winner-set (ring-ref winner-pending-undo-ring
+                           winner-undo-counter))
+                                        ; .. and new configuration
+      (let ((data (winner-win-data)))
+       (and (not (member data winner-undone-data))
+            (push data winner-undone-data))))
+     (return t))                       ; .. then everything is fine.
+    (t ;; Otherwise, discharge it (and try the next one).
+     (ring-remove winner-pending-undo-ring winner-undo-counter)))))
+
+
+(defun winner-redo ()                  ; If you change your mind.
+  "Restore a more recent window configuration saved by Winner mode."
+  (interactive)
+  (cond
+   ((eq last-command 'winner-undo)
+    (winner-set
+     (if (zerop (minibuffer-depth))
+         (ring-remove winner-pending-undo-ring 0)
+       (ring-ref winner-pending-undo-ring 0)))
+    (unless (eq (selected-window) (minibuffer-window))
+      (message "Winner undid undo")))
+   (t (error "Previous command was not a `winner-undo'"))))
+
+;;; To be evaluated when the package is loaded:
+
+(unless (or (assq 'winner-mode minor-mode-map-alist)
+           winner-dont-bind-my-keys)
+  (push (cons 'winner-mode winner-mode-map)
+       minor-mode-map-alist))
+
+(provide 'winner)
+;; arch-tag: 686d1c1b-010e-42ca-a192-b5685112418f
+;;; winner.el ends here