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Diffstat (limited to 'lisp/gnus/gnus-undo.el')
| -rw-r--r-- | lisp/gnus/gnus-undo.el | 173 |
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diff --git a/lisp/gnus/gnus-undo.el b/lisp/gnus/gnus-undo.el new file mode 100644 index 00000000000..ebae58e3002 --- /dev/null +++ b/lisp/gnus/gnus-undo.el @@ -0,0 +1,173 @@ +;;; gnus-undo.el --- minor mode for undoing in Gnus +;; Copyright (C) 1996,97 Free Software Foundation, Inc. + +;; Author: Lars Magne Ingebrigtsen <larsi@ifi.uio.no> +;; Keywords: news + +;; 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: + +;; This package allows arbitrary undoing in Gnus buffers. As all the +;; Gnus buffers aren't very text-oriented (what is in the buffers is +;; just some random representation of the actual data), normal Emacs +;; undoing doesn't work at all for Gnus. +;; +;; This package works by letting Gnus register functions for reversing +;; actions, and then calling these functions when the user pushes the +;; `undo' key. As with normal `undo', there it is possible to set +;; undo boundaries and so on. +;; +;; Internally, the undo sequence is represented by the +;; `gnus-undo-actions' list, where each element is a list of functions +;; to be called, in sequence, to undo some action. (An "action" is a +;; collection of functions.) +;; +;; For instance, a function for killing a group will call +;; `gnus-undo-register' with a function that un-kills the group. This +;; package will put that function into an action. + +;;; Code: + +(require 'gnus-util) +(require 'gnus) + +(defvar gnus-undo-mode nil + "Minor mode for undoing in Gnus buffers.") + +(defvar gnus-undo-mode-hook nil + "Hook called in all `gnus-undo-mode' buffers.") + +;;; Internal variables. + +(defvar gnus-undo-actions nil) +(defvar gnus-undo-boundary t) +(defvar gnus-undo-last nil) +(defvar gnus-undo-boundary-inhibit nil) + +;;; Minor mode definition. + +(defvar gnus-undo-mode-map nil) + +(unless gnus-undo-mode-map + (setq gnus-undo-mode-map (make-sparse-keymap)) + + (gnus-define-keys gnus-undo-mode-map + "\M-\C-_" gnus-undo + "\C-_" gnus-undo + "\C-xu" gnus-undo + [(control /)] gnus-undo ; many people are used to type `C-/' on + ; X terminals and get `C-_'. + )) + +(defun gnus-undo-make-menu-bar () + (when nil + (define-key-after (current-local-map) [menu-bar file gnus-undo] + (cons "Undo" 'gnus-undo-actions) + [menu-bar file whatever]))) + +(defun gnus-undo-mode (&optional arg) + "Minor mode for providing `undo' in Gnus buffers. + +\\{gnus-undo-mode-map}" + (interactive "P") + (set (make-local-variable 'gnus-undo-mode) + (if (null arg) (not gnus-undo-mode) + (> (prefix-numeric-value arg) 0))) + (set (make-local-variable 'gnus-undo-actions) nil) + (set (make-local-variable 'gnus-undo-boundary) t) + (when gnus-undo-mode + ;; Set up the menu. + (when (gnus-visual-p 'undo-menu 'menu) + (gnus-undo-make-menu-bar)) + ;; Don't display anything in the mode line -- too annoying. + ;;(unless (assq 'gnus-undo-mode minor-mode-alist) + ;; (push '(gnus-undo-mode " Undo") minor-mode-alist)) + (unless (assq 'gnus-undo-mode minor-mode-map-alist) + (push (cons 'gnus-undo-mode gnus-undo-mode-map) + minor-mode-map-alist)) + (make-local-hook 'post-command-hook) + (add-hook 'post-command-hook 'gnus-undo-boundary nil t) + (add-hook 'gnus-summary-exit-hook 'gnus-undo-boundary) + (run-hooks 'gnus-undo-mode-hook))) + +;;; Interface functions. + +(defun gnus-disable-undo (&optional buffer) + "Disable undoing in the current buffer." + (interactive) + (save-excursion + (when buffer + (set-buffer buffer)) + (gnus-undo-mode -1))) + +(defun gnus-undo-boundary () + "Set Gnus undo boundary." + (if gnus-undo-boundary-inhibit + (setq gnus-undo-boundary-inhibit nil) + (setq gnus-undo-boundary t))) + +(defun gnus-undo-register (form) + "Register FORMS as something to be performed to undo a change. +FORMS may use backtick quote syntax." + (when gnus-undo-mode + (gnus-undo-register-1 + `(lambda () + ,form)))) + +(put 'gnus-undo-register 'lisp-indent-function 0) +(put 'gnus-undo-register 'edebug-form-spec '(body)) + +(defun gnus-undo-register-1 (function) + "Register FUNCTION as something to be performed to undo a change." + (when gnus-undo-mode + (cond + ;; We are on a boundary, so we create a new action. + (gnus-undo-boundary + (push (list function) gnus-undo-actions) + (setq gnus-undo-boundary nil)) + ;; Prepend the function to an old action. + (gnus-undo-actions + (setcar gnus-undo-actions (cons function (car gnus-undo-actions)))) + ;; Initialize list. + (t + (setq gnus-undo-actions (list (list function))))) + (setq gnus-undo-boundary-inhibit t))) + +(defun gnus-undo (n) + "Undo some previous changes in Gnus buffers. +Repeat this command to undo more changes. +A numeric argument serves as a repeat count." + (interactive "p") + (unless gnus-undo-mode + (error "Undoing is not enabled in this buffer")) + (message "%s" last-command) + (when (or (not (eq last-command 'gnus-undo)) + (not gnus-undo-last)) + (setq gnus-undo-last gnus-undo-actions)) + (let ((action (pop gnus-undo-last))) + (unless action + (error "Nothing further to undo")) + (setq gnus-undo-actions (delq action gnus-undo-actions)) + (setq gnus-undo-boundary t) + (while action + (funcall (pop action))))) + +(provide 'gnus-undo) + +;;; gnus-undo.el ends here |