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55535639 | 1 | ;;; rot13.el --- display a buffer in rot13 |
c88ab9ce | 2 | |
9750e079 ER |
3 | ;; Copyright (C) 1988 Free Software Foundation, Inc. |
4 | ||
55535639 | 5 | ;; Author: Howard Gayle |
e5167999 | 6 | ;; Maintainer: FSF |
3b4a6e27 JB |
7 | |
8 | ;; This file is part of GNU Emacs. | |
9 | ||
10 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
11 | ;; it under the terms of the GNU General Public License as published by | |
e5167999 | 12 | ;; the Free Software Foundation; either version 2, or (at your option) |
3b4a6e27 JB |
13 | ;; any later version. |
14 | ||
15 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
16 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ;; GNU General Public License for more details. | |
19 | ||
20 | ;; You should have received a copy of the GNU General Public License | |
b578f267 EN |
21 | ;; along with GNU Emacs; see the file COPYING. If not, write to the |
22 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
23 | ;; Boston, MA 02111-1307, USA. | |
3b4a6e27 | 24 | |
07b3798c | 25 | ;;; Commentary: |
3b4a6e27 | 26 | |
716e9939 | 27 | ;; The single entry point, `rot13-other-window', performs a Caesar cipher |
d9ecc911 | 28 | ;; encrypt/decrypt on the current buffer and displays the result in another |
716e9939 | 29 | ;; window. Rot13 encryption is sometimes used on USENET as a read-at-your- |
d9ecc911 ER |
30 | ;; own-risk wrapper for material some might consider offensive, such as |
31 | ;; ethnic humor. | |
32 | ;; | |
716e9939 | 33 | ;; Written by Howard Gayle. |
3b4a6e27 JB |
34 | ;; This hack is mainly to show off the char table stuff. |
35 | ||
e5167999 ER |
36 | ;;; Code: |
37 | ||
3b4a6e27 JB |
38 | (defvar rot13-display-table |
39 | (let ((table (make-display-table)) | |
40 | (i 0)) | |
41 | (while (< i 26) | |
342df1e2 RS |
42 | (aset table (+ i ?a) (vector (+ (% (+ i 13) 26) ?a))) |
43 | (aset table (+ i ?A) (vector (+ (% (+ i 13) 26) ?A))) | |
3b4a6e27 JB |
44 | (setq i (1+ i))) |
45 | table) | |
46 | "Char table for rot 13 display.") | |
47 | ||
8931b34a | 48 | ;;;###autoload |
3b4a6e27 | 49 | (defun rot13-other-window () |
7d002ae1 | 50 | "Display current buffer in rot 13 in another window. |
c8c6b45a EZ |
51 | The text itself is not modified, only the way it is displayed is affected. |
52 | ||
53 | To terminate the rot13 display, delete that window. As long as that window | |
54 | is not deleted, any buffer displayed in it will become instantly encoded | |
55 | in rot 13. | |
56 | ||
1604ce98 | 57 | See also `toggle-rot13-mode'." |
3b4a6e27 JB |
58 | (interactive) |
59 | (let ((w (display-buffer (current-buffer) t))) | |
60 | (set-window-display-table w rot13-display-table))) | |
61 | ||
dcd12c89 RS |
62 | ;;;###autoload |
63 | (defun toggle-rot13-mode () | |
64 | "Toggle the use of rot 13 encoding for the current window." | |
65 | (interactive) | |
66 | (if (eq (window-display-table (selected-window)) rot13-display-table) | |
67 | (set-window-display-table (selected-window) nil) | |
68 | (if (null (window-display-table (selected-window))) | |
69 | (set-window-display-table (selected-window) rot13-display-table)))) | |
70 | ||
3b4a6e27 | 71 | (provide 'rot13) |
c88ab9ce ER |
72 | |
73 | ;;; rot13.el ends here |