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1 | ;;; gnus-undo.el --- minor mode for undoing in Gnus |
2 | ;; Copyright (C) 1996,97 Free Software Foundation, Inc. | |
3 | ||
4 | ;; Author: Lars Magne Ingebrigtsen <larsi@ifi.uio.no> | |
5 | ;; Keywords: news | |
6 | ||
7 | ;; This file is part of GNU Emacs. | |
8 | ||
9 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
10 | ;; it under the terms of the GNU General Public License as published by | |
11 | ;; the Free Software Foundation; either version 2, or (at your option) | |
12 | ;; any later version. | |
13 | ||
14 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
15 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | ;; GNU General Public License for more details. | |
18 | ||
19 | ;; You should have received a copy of the GNU General Public License | |
20 | ;; along with GNU Emacs; see the file COPYING. If not, write to the | |
21 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
22 | ;; Boston, MA 02111-1307, USA. | |
23 | ||
24 | ;;; Commentary: | |
25 | ||
26 | ;; This package allows arbitrary undoing in Gnus buffers. As all the | |
27 | ;; Gnus buffers aren't very text-oriented (what is in the buffers is | |
28 | ;; just some random representation of the actual data), normal Emacs | |
29 | ;; undoing doesn't work at all for Gnus. | |
30 | ;; | |
31 | ;; This package works by letting Gnus register functions for reversing | |
32 | ;; actions, and then calling these functions when the user pushes the | |
33 | ;; `undo' key. As with normal `undo', there it is possible to set | |
34 | ;; undo boundaries and so on. | |
35 | ;; | |
36 | ;; Internally, the undo sequence is represented by the | |
37 | ;; `gnus-undo-actions' list, where each element is a list of functions | |
38 | ;; to be called, in sequence, to undo some action. (An "action" is a | |
39 | ;; collection of functions.) | |
40 | ;; | |
41 | ;; For instance, a function for killing a group will call | |
42 | ;; `gnus-undo-register' with a function that un-kills the group. This | |
43 | ;; package will put that function into an action. | |
44 | ||
45 | ;;; Code: | |
46 | ||
47 | (require 'gnus-util) | |
48 | (require 'gnus) | |
49 | ||
50 | (defvar gnus-undo-mode nil | |
51 | "Minor mode for undoing in Gnus buffers.") | |
52 | ||
53 | (defvar gnus-undo-mode-hook nil | |
54 | "Hook called in all `gnus-undo-mode' buffers.") | |
55 | ||
56 | ;;; Internal variables. | |
57 | ||
58 | (defvar gnus-undo-actions nil) | |
59 | (defvar gnus-undo-boundary t) | |
60 | (defvar gnus-undo-last nil) | |
61 | (defvar gnus-undo-boundary-inhibit nil) | |
62 | ||
63 | ;;; Minor mode definition. | |
64 | ||
65 | (defvar gnus-undo-mode-map nil) | |
66 | ||
67 | (unless gnus-undo-mode-map | |
68 | (setq gnus-undo-mode-map (make-sparse-keymap)) | |
69 | ||
70 | (gnus-define-keys gnus-undo-mode-map | |
71 | "\M-\C-_" gnus-undo | |
72 | "\C-_" gnus-undo | |
73 | "\C-xu" gnus-undo | |
74 | [(control /)] gnus-undo ; many people are used to type `C-/' on | |
75 | ; X terminals and get `C-_'. | |
76 | )) | |
77 | ||
78 | (defun gnus-undo-make-menu-bar () | |
79 | (when nil | |
80 | (define-key-after (current-local-map) [menu-bar file gnus-undo] | |
81 | (cons "Undo" 'gnus-undo-actions) | |
82 | [menu-bar file whatever]))) | |
83 | ||
84 | (defun gnus-undo-mode (&optional arg) | |
85 | "Minor mode for providing `undo' in Gnus buffers. | |
86 | ||
87 | \\{gnus-undo-mode-map}" | |
88 | (interactive "P") | |
89 | (set (make-local-variable 'gnus-undo-mode) | |
90 | (if (null arg) (not gnus-undo-mode) | |
91 | (> (prefix-numeric-value arg) 0))) | |
92 | (set (make-local-variable 'gnus-undo-actions) nil) | |
93 | (set (make-local-variable 'gnus-undo-boundary) t) | |
94 | (when gnus-undo-mode | |
95 | ;; Set up the menu. | |
96 | (when (gnus-visual-p 'undo-menu 'menu) | |
97 | (gnus-undo-make-menu-bar)) | |
98 | ;; Don't display anything in the mode line -- too annoying. | |
99 | ;;(unless (assq 'gnus-undo-mode minor-mode-alist) | |
100 | ;; (push '(gnus-undo-mode " Undo") minor-mode-alist)) | |
101 | (unless (assq 'gnus-undo-mode minor-mode-map-alist) | |
102 | (push (cons 'gnus-undo-mode gnus-undo-mode-map) | |
103 | minor-mode-map-alist)) | |
104 | (make-local-hook 'post-command-hook) | |
105 | (add-hook 'post-command-hook 'gnus-undo-boundary nil t) | |
106 | (add-hook 'gnus-summary-exit-hook 'gnus-undo-boundary) | |
107 | (run-hooks 'gnus-undo-mode-hook))) | |
108 | ||
109 | ;;; Interface functions. | |
110 | ||
111 | (defun gnus-disable-undo (&optional buffer) | |
112 | "Disable undoing in the current buffer." | |
113 | (interactive) | |
114 | (save-excursion | |
115 | (when buffer | |
116 | (set-buffer buffer)) | |
117 | (gnus-undo-mode -1))) | |
118 | ||
119 | (defun gnus-undo-boundary () | |
120 | "Set Gnus undo boundary." | |
121 | (if gnus-undo-boundary-inhibit | |
122 | (setq gnus-undo-boundary-inhibit nil) | |
123 | (setq gnus-undo-boundary t))) | |
124 | ||
125 | (defun gnus-undo-register (form) | |
126 | "Register FORMS as something to be performed to undo a change. | |
127 | FORMS may use backtick quote syntax." | |
128 | (when gnus-undo-mode | |
129 | (gnus-undo-register-1 | |
130 | `(lambda () | |
131 | ,form)))) | |
132 | ||
133 | (put 'gnus-undo-register 'lisp-indent-function 0) | |
134 | (put 'gnus-undo-register 'edebug-form-spec '(body)) | |
135 | ||
136 | (defun gnus-undo-register-1 (function) | |
137 | "Register FUNCTION as something to be performed to undo a change." | |
138 | (when gnus-undo-mode | |
139 | (cond | |
140 | ;; We are on a boundary, so we create a new action. | |
141 | (gnus-undo-boundary | |
142 | (push (list function) gnus-undo-actions) | |
143 | (setq gnus-undo-boundary nil)) | |
144 | ;; Prepend the function to an old action. | |
145 | (gnus-undo-actions | |
146 | (setcar gnus-undo-actions (cons function (car gnus-undo-actions)))) | |
147 | ;; Initialize list. | |
148 | (t | |
149 | (setq gnus-undo-actions (list (list function))))) | |
150 | (setq gnus-undo-boundary-inhibit t))) | |
151 | ||
152 | (defun gnus-undo (n) | |
153 | "Undo some previous changes in Gnus buffers. | |
154 | Repeat this command to undo more changes. | |
155 | A numeric argument serves as a repeat count." | |
156 | (interactive "p") | |
157 | (unless gnus-undo-mode | |
158 | (error "Undoing is not enabled in this buffer")) | |
159 | (message "%s" last-command) | |
160 | (when (or (not (eq last-command 'gnus-undo)) | |
161 | (not gnus-undo-last)) | |
162 | (setq gnus-undo-last gnus-undo-actions)) | |
163 | (let ((action (pop gnus-undo-last))) | |
164 | (unless action | |
165 | (error "Nothing further to undo")) | |
166 | (setq gnus-undo-actions (delq action gnus-undo-actions)) | |
167 | (setq gnus-undo-boundary t) | |
168 | (while action | |
169 | (funcall (pop action))))) | |
170 | ||
171 | (provide 'gnus-undo) | |
172 | ||
173 | ;;; gnus-undo.el ends here |