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1 ;;; gnus-undo.el --- minor mode for undoing in Gnus
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2 ;; Copyright (C) 1996,97 Free Software Foundation, Inc.
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3
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4 ;; Author: Lars Magne Ingebrigtsen <larsi@ifi.uio.no>
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5 ;; Keywords: news
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6
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7 ;; This file is part of GNU Emacs.
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8
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9 ;; GNU Emacs is free software; you can redistribute it and/or modify
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10 ;; it under the terms of the GNU General Public License as published by
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11 ;; the Free Software Foundation; either version 2, or (at your option)
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12 ;; any later version.
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13
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14 ;; GNU Emacs is distributed in the hope that it will be useful,
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15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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17 ;; GNU General Public License for more details.
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18
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19 ;; You should have received a copy of the GNU General Public License
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20 ;; along with GNU Emacs; see the file COPYING. If not, write to the
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21 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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22 ;; Boston, MA 02111-1307, USA.
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23
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24 ;;; Commentary:
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25
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26 ;; This package allows arbitrary undoing in Gnus buffers. As all the
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27 ;; Gnus buffers aren't very text-oriented (what is in the buffers is
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28 ;; just some random representation of the actual data), normal Emacs
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29 ;; undoing doesn't work at all for Gnus.
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30 ;;
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31 ;; This package works by letting Gnus register functions for reversing
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32 ;; actions, and then calling these functions when the user pushes the
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33 ;; `undo' key. As with normal `undo', there it is possible to set
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34 ;; undo boundaries and so on.
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35 ;;
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36 ;; Internally, the undo sequence is represented by the
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37 ;; `gnus-undo-actions' list, where each element is a list of functions
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38 ;; to be called, in sequence, to undo some action. (An "action" is a
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39 ;; collection of functions.)
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40 ;;
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41 ;; For instance, a function for killing a group will call
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42 ;; `gnus-undo-register' with a function that un-kills the group. This
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43 ;; package will put that function into an action.
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44
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45 ;;; Code:
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46
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47 (require 'gnus-util)
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48 (require 'gnus)
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49
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50 (defvar gnus-undo-mode nil
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51 "Minor mode for undoing in Gnus buffers.")
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52
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53 (defvar gnus-undo-mode-hook nil
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54 "Hook called in all `gnus-undo-mode' buffers.")
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55
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56 ;;; Internal variables.
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57
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58 (defvar gnus-undo-actions nil)
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59 (defvar gnus-undo-boundary t)
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60 (defvar gnus-undo-last nil)
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61 (defvar gnus-undo-boundary-inhibit nil)
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62
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63 ;;; Minor mode definition.
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64
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65 (defvar gnus-undo-mode-map nil)
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66
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67 (unless gnus-undo-mode-map
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68 (setq gnus-undo-mode-map (make-sparse-keymap))
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69
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70 (gnus-define-keys gnus-undo-mode-map
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118
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71 "\M-\C-_" gnus-undo
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72 "\C-_" gnus-undo
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73 "\C-xu" gnus-undo
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140
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74 ;; many people are used to type `C-/' on X terminals and get `C-_'.
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75 [(control /)] gnus-undo))
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98
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76
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77 (defun gnus-undo-make-menu-bar ()
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140
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78 ;; This is disabled for the time being.
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98
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79 (when nil
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140
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80 (define-key-after (current-local-map) [menu-bar file gnus-undo]
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81 (cons "Undo" 'gnus-undo-actions)
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82 [menu-bar file whatever])))
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98
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83
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84 (defun gnus-undo-mode (&optional arg)
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85 "Minor mode for providing `undo' in Gnus buffers.
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86
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87 \\{gnus-undo-mode-map}"
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88 (interactive "P")
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89 (set (make-local-variable 'gnus-undo-mode)
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90 (if (null arg) (not gnus-undo-mode)
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91 (> (prefix-numeric-value arg) 0)))
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92 (set (make-local-variable 'gnus-undo-actions) nil)
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93 (set (make-local-variable 'gnus-undo-boundary) t)
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94 (when gnus-undo-mode
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95 ;; Set up the menu.
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96 (when (gnus-visual-p 'undo-menu 'menu)
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97 (gnus-undo-make-menu-bar))
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98 ;; Don't display anything in the mode line -- too annoying.
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99 ;;(unless (assq 'gnus-undo-mode minor-mode-alist)
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100 ;; (push '(gnus-undo-mode " Undo") minor-mode-alist))
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101 (unless (assq 'gnus-undo-mode minor-mode-map-alist)
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102 (push (cons 'gnus-undo-mode gnus-undo-mode-map)
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103 minor-mode-map-alist))
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104 (make-local-hook 'post-command-hook)
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122
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105 (add-hook 'post-command-hook 'gnus-undo-boundary nil t)
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98
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106 (run-hooks 'gnus-undo-mode-hook)))
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107
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108 ;;; Interface functions.
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109
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110 (defun gnus-disable-undo (&optional buffer)
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111 "Disable undoing in the current buffer."
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112 (interactive)
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113 (save-excursion
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114 (when buffer
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115 (set-buffer buffer))
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116 (gnus-undo-mode -1)))
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117
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118 (defun gnus-undo-boundary ()
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119 "Set Gnus undo boundary."
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120 (if gnus-undo-boundary-inhibit
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121 (setq gnus-undo-boundary-inhibit nil)
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122 (setq gnus-undo-boundary t)))
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123
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140
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124 (defun gnus-undo-force-boundary ()
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125 "Set Gnus undo boundary."
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126 (setq gnus-undo-boundary-inhibit nil
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127 gnus-undo-boundary t))
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128
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129 (defun gnus-undo-register (form)
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130 "Register FORMS as something to be performed to undo a change.
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131 FORMS may use backtick quote syntax."
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132 (when gnus-undo-mode
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133 (gnus-undo-register-1
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134 `(lambda ()
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135 ,form))))
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136
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137 (put 'gnus-undo-register 'lisp-indent-function 0)
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138 (put 'gnus-undo-register 'edebug-form-spec '(body))
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139
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140 (defun gnus-undo-register-1 (function)
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141 "Register FUNCTION as something to be performed to undo a change."
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142 (when gnus-undo-mode
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143 (cond
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144 ;; We are on a boundary, so we create a new action.
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145 (gnus-undo-boundary
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146 (push (list function) gnus-undo-actions)
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147 (setq gnus-undo-boundary nil))
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148 ;; Prepend the function to an old action.
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149 (gnus-undo-actions
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150 (setcar gnus-undo-actions (cons function (car gnus-undo-actions))))
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151 ;; Initialize list.
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152 (t
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153 (setq gnus-undo-actions (list (list function)))))
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154 (setq gnus-undo-boundary-inhibit t)))
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155
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156 (defun gnus-undo (n)
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157 "Undo some previous changes in Gnus buffers.
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158 Repeat this command to undo more changes.
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159 A numeric argument serves as a repeat count."
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160 (interactive "p")
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161 (unless gnus-undo-mode
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162 (error "Undoing is not enabled in this buffer"))
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163 (message "%s" last-command)
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164 (when (or (not (eq last-command 'gnus-undo))
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165 (not gnus-undo-last))
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166 (setq gnus-undo-last gnus-undo-actions))
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167 (let ((action (pop gnus-undo-last)))
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168 (unless action
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169 (error "Nothing further to undo"))
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170 (setq gnus-undo-actions (delq action gnus-undo-actions))
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171 (setq gnus-undo-boundary t)
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172 (while action
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173 (funcall (pop action)))))
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174
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175 (provide 'gnus-undo)
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176
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177 ;;; gnus-undo.el ends here
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