(TAGS-LISP): Don't use `$(lispsource)'.
[bpt/emacs.git] / lisp / winner.el
dissimilarity index 83%
index 15a8699..2e35995 100644 (file)
-;;; winner.el  --- Restore window configuration or change 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.el provides a minor mode (`winner-mode') that does
-;;   essentially two things:
-;;
-;;     1) It keeps track of changing window configurations, so that
-;;        when you wish to go back to a previous view, all you have
-;;        to do is to press C-left a couple of times.
-;;
-;;     2) It lets you switch to other buffers by pressing C-right.
-;;
-;; To use Winner mode, put this line in your .emacs file:
-;;
-;;      (add-hook 'after-init-hook (lambda () (winner-mode 1)))
-\f
-;; Details:
-;;
-;;   1. You may of course decide to use other bindings than those
-;;      mentioned above.  Just set these variables in your .emacs:
-;;
-;;          `winner-prev-event'
-;;          `winner-next-event'
-;;
-;;   2. When you have found the view of  your choice
-;;      (using your favourite keys), you may press ctrl-space
-;;      (`winner-max-event') to `delete-other-windows'.
-;;
-;;   3. Winner now keeps one configuration stack for each frame.
-;;
-;;
-;;
-;;                           Yours sincerely,   Ivar Rummelhoff
-;;
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-
-;;; Code:
-
-
-
-;;;; Variables you may want to change
-
-(defvar winner-prev-event 'C-left
-  "Winner mode binds this event to the command `winner-previous'.")
-
-(defvar winner-next-event 'C-right
-  "Winner mode binds this event to the command `winner-next'.")
-
-(defvar winner-max-event 67108896      ; CTRL-space
-  "Event for deleting other windows
-after having selected a view with Winner.
-
-The normal functions of this event will also be performed.
-In the default case (CTRL-SPACE) the mark will be set.")
-
-(defvar winner-skip-buffers
-  '("*Messages*",
-    "*Compile-Log*",
-    ".newsrc-dribble",
-    "*Completions*",
-    "*Buffer list*")
-  "Exclude these buffer names
-from any \(Winner mode\) list of buffers.")
-
-(defvar winner-skip-regexps '("^ ")
-  "Exclude buffers with names matching any of these regexps.
-..from any \(Winner mode\) list of buffers.
-
-By default `winner-skip-regexps' is set to \(\"^ \"\),
-which excludes \"invisible buffers\".")
-
-\f
-(defvar winner-limit 50
-  "Winner will save no more than 2 * `winner-limit' window configurations.
-\(.. and no less than `winner-limit'.\)")
-
-(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-dont-bind-my-keys nil
-  "If non-nil: Do not use `winner-mode-map' in Winner mode.")
-
-
-
-;;;; Winner mode
-
-(eval-when-compile (require 'cl))
-
-
-(defvar winner-mode nil)               ; For the modeline.
-(defvar winner-mode-map nil "Keymap for Winner mode.")
-
-;;;###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
-     (on-p (let ((winner-frames-changed (frame-list)))
-            (winner-do-save))          ; Save current configurations
-          (add-hook 'window-configuration-change-hook 'winner-save-configuration)
-          (setq winner-mode t)
-          (run-hooks 'winner-mode-hook))
-     (t (remove-hook 'window-configuration-change-hook 'winner-save-configuration)
-       (when winner-mode
-         (setq winner-mode nil)
-         (run-hooks 'winner-mode-leave-hook))))
-    (force-mode-line-update)))
-
-
-;; List of frames which have changed
-(defvar winner-frames-changed nil)
-
-;; Time to save the window configuration.
-(defun winner-save-configuration ()
-  (push (selected-frame) winner-frames-changed)
-  (add-hook 'post-command-hook 'winner-do-save))
-
-\f
-(defun winner-do-save ()
-  (let ((current (selected-frame)))
-    (unwind-protect
-       (do ((frames winner-frames-changed (cdr frames)))
-           ((null frames))
-         (unless (memq (car frames) (cdr frames))
-           ;; Process each frame once.
-           (select-frame (car frames))
-           (winner-push (current-window-configuration) (car frames))))
-      (setq winner-frames-changed nil)
-      (select-frame current)
-      (remove-hook 'post-command-hook 'winner-do-save))))
-
-
-
-
-
-;;;; Configuration stacks (one for each frame)
-
-
-(defvar winner-stacks nil) ; ------ " ------
-
-
-;; A stack of window configurations with some additional information.
-(defstruct (winner-stack
-           (:constructor winner-stack-new
-                         (config &aux
-                                 (data (list config))
-                                 (place data))))
-  data place (count 1))
-
-
-;; Return the stack of this frame
-(defun winner-stack (frame)
-  (let ((stack (cdr (assq frame winner-stacks))))
-    (if stack (winner-stack-data stack)
-      ;; Else make new stack
-      (letf (((selected-frame) frame))
-       (let ((config (current-window-configuration)))
-         (push (cons frame (winner-stack-new config))
-               winner-stacks)
-         (list config))))))
-
-
-
-\f
-;; Push this window configuration on the right stack,
-;; but make sure the stack doesn't get too large etc...
-(defun winner-push (config frame)
-  (let ((this (cdr (assq frame winner-stacks))))
-    (if (not this) (push (cons frame (winner-stack-new config))
-                        winner-stacks)
-      (push config (winner-stack-data this))
-      (when (> (incf (winner-stack-count this)) winner-limit)
-       ;; No more than 2*winner-limit configs
-       (setcdr (winner-stack-place this) nil)
-       (setf   (winner-stack-place this)
-               (winner-stack-data  this))
-       (setf   (winner-stack-count this) 1)))))
-
-
-
-
-
-
-
-
-;;;; Selecting a window configuration
-
-
-;; Return list of names of other buffers, excluding the current buffer
-;; and buffers specified by the user.
-(defun winner-other-buffers ()
-  (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))
-
-
-
-(defun winner-select (&optional arg)
-
-  "Change to previous or new window configuration.
-With arg start at position 1 if arg is positive, and
-at -1 if arg is negative;  else start at position 0.
-\(For Winner to record changes in window configurations,
-Winner mode must be turned on.\)"
-  (interactive "P")
-
-  (setq arg
-       (cond
-        ((not arg) nil)
-        ((> (prefix-numeric-value arg) 0) winner-next-event)
-        ((< (prefix-numeric-value arg) 0) winner-prev-event)
-        (t nil)))
-  (if arg (push arg unread-command-events))
-\f
-  (let ((stack (winner-stack (selected-frame)))
-       (store nil)
-       (buffers (winner-other-buffers))
-       (passed nil)
-       (config (current-window-configuration))
-       (pos 0) event)
-    ;; `stack'   and `store'  are stacks of window configuration while
-    ;; `buffers' and `passed' are stacks of buffer names.
-
-    (condition-case nil
-
-       (loop
-        (setq event (read-event))
-        (cond
-
-         ((eq event winner-prev-event)
-          (cond (passed     (push (pop passed) buffers)(decf pos))
-                ((cdr stack)(push (pop stack)  store)  (decf pos))
-                (t (setq stack (append (nreverse store) stack))
-                   (setq store nil)
-                   (setq pos   0))))
-
-         ((eq event winner-next-event)
-          (cond (store   (push (pop store)   stack)  (incf pos))
-                (buffers (push (pop buffers) passed) (incf pos))
-                (t (setq buffers (nreverse passed))
-                   (setq passed nil)
-                   (setq pos 0))))
-
-         ((eq event winner-max-event)
-          ;; Delete other windows and leave.
-          (delete-other-windows)
-          ;; Let this change be saved.
-          (setq pos -1)
-          ;; Perform other actions of this event.
-          (push event unread-command-events)
-          (return))
-         (t (push event unread-command-events) (return)))
-
-        (cond
-         ;; Display
-         (passed (set-window-buffer (selected-window) (car passed))
-                 (message (concat "Winner\(%d\): [%s] "
-                                  (mapconcat 'identity buffers " "))
-                          pos (car passed)))
-
-         (t (set-window-configuration (car stack))
-            (if (window-minibuffer-p (selected-window))
-                (other-window 1))
-            (message "Winner\(%d\)" pos))))
-
-      (quit (set-window-configuration config)
-           (setq pos 0)))
-    (if (zerop pos)
-       ;; Do not record these changes.
-       (remove-hook 'post-command-hook 'winner-do-save)
-      ;; Else update the buffer list and make sure that the displayed
-      ;; buffer is the same as the current buffer.
-      (switch-to-buffer (window-buffer)))))
-\f                                         
-                                          
-
-
-
-(defun winner-previous ()
-  "Change to previous window configuration."
-  (interactive)
-  (winner-select -1))
-
-(defun winner-next ()
-  "Change to new window configuration."
-  (interactive)
-  (winner-select 1))
-
-
-
-
-;;;; To be evaluated when the package is loaded:
-
-(unless winner-mode-map
-  (setq winner-mode-map (make-sparse-keymap))
-  (define-key winner-mode-map (vector winner-prev-event) 'winner-previous)
-  (define-key winner-mode-map (vector winner-next-event) 'winner-next))
-
-(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 Free Software Foundation. Inc.
+
+;; Author: Ivar Rummelhoff <ivarru@math.uio.no>
+;; Created: 27 Feb 1997
+;; Time-stamp: <1998-08-21 19:51:02 ivarr>
+;; 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., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, 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-x left.  If you change your mind (while undoing), you can
+;; press ctrl-x 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.
+
+;;; Code:
+
+(eval-when-compile
+  (require 'cl))
+
+(eval-when-compile
+  (cond
+   ((eq (aref (emacs-version) 0) ?X)
+    (defmacro winner-active-region ()
+      '(region-active-p))
+    (defsetf winner-active-region () (store)
+      `(if ,store (zmacs-activate-region)
+        (zmacs-deactivate-region))))
+   (t (defmacro winner-active-region ()
+       'mark-active)
+      (defsetf winner-active-region () (store)
+       `(setq mark-active ,store)))) )
+
+(require 'ring)
+
+(when (fboundp 'defgroup)
+  (defgroup winner nil
+    "Restoring window configurations."
+    :group 'windows))
+
+(unless (fboundp 'defcustom)
+  (defmacro defcustom (symbol &optional initvalue docs &rest rest)
+    (list 'defvar symbol initvalue docs)))
+
+\f
+;;;###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)
+          (winner-mode (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)
+
+
+
+
+;;;; Saving old configurations (internal variables and subroutines)
+
+;; This variable is updated with the current window configuration
+;; after every command, so that when command make changes in the
+;; window configuration, the last configuration can be saved.
+(defvar winner-currents nil)
+
+;; The current configuration (+ the buffers involved).
+(defsubst winner-conf ()
+  (list (current-window-configuration)
+       (loop for w being the windows
+             unless (window-minibuffer-p w)
+             collect (window-buffer w)) ))
+;;     (if winner-testvar (incf winner-testvar) ; For debugging purposes
+;;       (setq winner-testvar 0))))
+
+;; Save current configuration.
+;; (Called by `winner-save-old-configurations' below).
+(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))))
+
+
+
+;; 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))
+      (progn
+       (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)
+
+;; Save the current window configuration, if it has changed.
+;; Then return frame, else 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)))
+       (ring-remove ring 0))
+      (ring-insert ring conf)
+      (push frame winner-last-frames)
+      frame)))
+
+;; 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 (memq (selected-frame) winner-modified-list)
+    (push (selected-frame) winner-modified-list)))
+
+
+;; For Emacs20 (a `post-command-hook').
+(defun winner-save-old-configurations ()
+  (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)
+  ;;  (ir-trace ; For debugging purposes
+  ;;   "%S"
+  ;;   (loop with ring = (winner-ring (selected-frame))
+  ;;    for i from 0 to (1- (ring-length ring))
+  ;;    collect (caddr (ring-ref ring i))))
+  (winner-remember))
+
+;; For compatibility with other emacsen
+;; and called by `winner-undo' before "undoing".
+(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))
+
+
+
+
+\f;;;; Restoring configurations
+
+;; Works almost as `set-window-configuration',
+;; but doesn't change the contents or the size of the minibuffer.
+(defun winner-set-conf (winconf)
+  (let ((miniwin (minibuffer-window))
+       (minisel (window-minibuffer-p (selected-window))))
+    (let ((minibuf   (window-buffer miniwin))
+         (minipoint (window-point  miniwin))
+         (minisize  (window-height miniwin)))
+      (set-window-configuration winconf)
+      (setf (window-buffer miniwin) minibuf
+           (window-point  miniwin) minipoint)
+      (when (/= minisize (window-height miniwin)) 
+       (letf (((selected-window) miniwin) )
+         ;; Clumsy due to cl-macs-limitation
+         (setf (window-height) minisize)))
+      (cond
+       (minisel (select-window miniwin))
+       ((window-minibuffer-p (selected-window))
+       (other-window 1))))))
+
+
+(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
+         with entry 
+         for win being the windows
+         do (cond
+             ((window-minibuffer-p win))
+             ((setq entry (assq win alist)) 
+              ;; Update existing entry
+              (push (cons win (window-point win))
+                    (cddr entry)))
+             (t;; Else create new entry
+              (push (list (set-buffer (window-buffer win))
+                          (cons (mark t) (winner-active-region))
+                          (cons win (window-point win)))
+                    alist)))
+         finally return alist)))
+
+
+(defun winner-get-point (buf win)
+  ;; Consult (and possibly extend) `winner-point-alist'.
+  (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 doesn't end up in the minibuffer and
+;; delete windows displaying dead buffers.  Return nil
+;; if and only if all the windows should have been deleted.
+;; Do not move neither points nor marks.
+(defun winner-set (conf)
+  (let* ((buffers nil)
+        (origpoints
+         (loop for buf in (cadr 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) ; These windows should be deleted
+      (loop for win being the windows
+           unless (window-minibuffer-p win)
+           do (if (pop origpoints)
+                  (setf (window-point win)
+                        ;; Restore point
+                        (winner-get-point
+                         (window-buffer win)
+                         win))
+                (push win xwins))) ; delete this window
+      ;; Restore mark
+      (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.
+      ;; Return t if this is still a possible configuration.
+      (or (null xwins)
+         (progn (mapcar 'delete-window (cdr xwins))
+                (if (one-window-p t)
+                    nil  ; No windows left
+                  (progn (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 nil "Keymap for Winner mode.")
+
+;; Is `window-configuration-change-hook' 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-unconditionally)))
+      (setq winner-modified-list (frame-list))
+      (winner-save-old-configurations)
+      (run-hooks 'winner-mode-hook))
+     ;; 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-unconditionally)
+      (run-hooks 'winner-mode-leave-hook)))
+    (force-mode-line-update)))
+
+\f;; 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-unconditionally)   ; 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)))))))
+(defun winner-win-data () 
+  ;; Essential properties of the windows in the selected frame.
+  (loop for win being the windows
+       unless (window-minibuffer-p win)
+       collect (list (window-buffer win)
+                     (window-width  win)
+                     (window-height win))))
+\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 all right.
+    (t                                 ; Else; discharge it and try another 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
+     (ring-remove winner-pending-undo-ring 0))
+    (unless (eq (selected-window) (minibuffer-window))
+      (message "Winner undid undo")))
+   (t (error "Previous command was not a winner-undo"))))
+\f
+;;; To be evaluated when the package is loaded:
+
+(if (fboundp 'compare-window-configurations)
+    (defalias 'winner-equal 'compare-window-configurations)
+  (defalias 'winner-equal 'equal))
+
+(unless winner-mode-map
+  (setq winner-mode-map (make-sparse-keymap))
+  (define-key winner-mode-map [(control x) left] 'winner-undo)
+  (define-key winner-mode-map [(control 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