1 ;;; gnus-undo.el --- minor mode for undoing in Gnus
2 ;; Copyright (C) 1996,97,98,99 Free Software Foundation, Inc.
4 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
7 ;; This file is part of GNU Emacs.
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)
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.
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.
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 arbitrary representation of the actual data), normal Emacs
29 ;; undoing doesn't work at all for Gnus.
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.
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.)
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.
47 (eval-when-compile (require 'cl))
53 (defgroup gnus-undo nil
54 "Undoing in Gnus buffers."
57 (defcustom gnus-undo-limit 2000
58 "The number of undoable actions recorded."
62 (defcustom gnus-undo-mode nil
63 "Minor mode for undoing in Gnus buffers."
67 (defcustom gnus-undo-mode-hook nil
68 "Hook called in all `gnus-undo-mode' buffers."
72 ;;; Internal variables.
74 (defvar gnus-undo-actions nil)
75 (defvar gnus-undo-boundary t)
76 (defvar gnus-undo-last nil)
77 (defvar gnus-undo-boundary-inhibit nil)
79 ;;; Minor mode definition.
81 (defvar gnus-undo-mode-map nil)
83 (unless gnus-undo-mode-map
84 (setq gnus-undo-mode-map (make-sparse-keymap))
86 (gnus-define-keys gnus-undo-mode-map
90 ;; many people are used to type `C-/' on X terminals and get `C-_'.
91 [(control /)] gnus-undo))
93 (defun gnus-undo-make-menu-bar ()
94 ;; This is disabled for the time being.
96 (define-key-after (current-local-map) [menu-bar file gnus-undo]
97 (cons "Undo" 'gnus-undo-actions)
98 [menu-bar file whatever])))
100 (defun gnus-undo-mode (&optional arg)
101 "Minor mode for providing `undo' in Gnus buffers.
103 \\{gnus-undo-mode-map}"
105 (set (make-local-variable 'gnus-undo-mode)
106 (if (null arg) (not gnus-undo-mode)
107 (> (prefix-numeric-value arg) 0)))
108 (set (make-local-variable 'gnus-undo-actions) nil)
109 (set (make-local-variable 'gnus-undo-boundary) t)
112 (when (gnus-visual-p 'undo-menu 'menu)
113 (gnus-undo-make-menu-bar))
114 (gnus-add-minor-mode 'gnus-undo-mode "" gnus-undo-mode-map)
115 (make-local-hook 'post-command-hook)
116 (add-hook 'post-command-hook 'gnus-undo-boundary nil t)
117 (gnus-run-hooks 'gnus-undo-mode-hook)))
119 ;;; Interface functions.
121 (defun gnus-disable-undo (&optional buffer)
122 "Disable undoing in the current buffer."
127 (gnus-undo-mode -1)))
129 (defun gnus-undo-boundary ()
130 "Set Gnus undo boundary."
131 (if gnus-undo-boundary-inhibit
132 (setq gnus-undo-boundary-inhibit nil)
133 (setq gnus-undo-boundary t)))
135 (defun gnus-undo-force-boundary ()
136 "Set Gnus undo boundary."
137 (setq gnus-undo-boundary-inhibit nil
138 gnus-undo-boundary t))
140 (defun gnus-undo-register (form)
141 "Register FORMS as something to be performed to undo a change.
142 FORMS may use backtick quote syntax."
144 (gnus-undo-register-1
148 (put 'gnus-undo-register 'lisp-indent-function 0)
149 (put 'gnus-undo-register 'edebug-form-spec '(body))
151 (defun gnus-undo-register-1 (function)
152 "Register FUNCTION as something to be performed to undo a change."
155 ;; We are on a boundary, so we create a new action.
157 (push (list function) gnus-undo-actions)
158 (setq gnus-undo-boundary nil))
159 ;; Prepend the function to an old action.
161 (setcar gnus-undo-actions (cons function (car gnus-undo-actions))))
164 (setq gnus-undo-actions (list (list function)))))
165 ;; Limit the length of the undo list.
166 (let ((next (nthcdr gnus-undo-limit gnus-undo-actions)))
169 ;; We are not at a boundary...
170 (setq gnus-undo-boundary-inhibit t)))
173 "Undo some previous changes in Gnus buffers.
174 Repeat this command to undo more changes.
175 A numeric argument serves as a repeat count."
177 (unless gnus-undo-mode
178 (error "Undoing is not enabled in this buffer"))
179 (message "%s" last-command)
180 (when (or (not (eq last-command 'gnus-undo))
181 (not gnus-undo-last))
182 (setq gnus-undo-last gnus-undo-actions))
183 (let ((action (pop gnus-undo-last)))
185 (error "Nothing further to undo"))
186 (setq gnus-undo-actions (delq action gnus-undo-actions))
187 (setq gnus-undo-boundary t)
189 (funcall (pop action)))))
193 ;;; gnus-undo.el ends here