| 1 | ;;; rot13.el --- display a buffer in rot13. |
| 2 | |
| 3 | ;; Copyright (C) 1988 Free Software Foundation, Inc. |
| 4 | |
| 5 | ;; Author: Howard Gayle: |
| 6 | ;; Maintainer: FSF |
| 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 |
| 12 | ;; the Free Software Foundation; either version 2, or (at your option) |
| 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 |
| 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. |
| 24 | |
| 25 | ;;; Commentary: |
| 26 | |
| 27 | ;; The single entry point, `rot13-other-window', performs a Caesar cipher |
| 28 | ;; encrypt/decrypt on the current buffer and displays the result in another |
| 29 | ;; window. Rot13 encryption is sometimes used on USENET as a read-at-your- |
| 30 | ;; own-risk wrapper for material some might consider offensive, such as |
| 31 | ;; ethnic humor. |
| 32 | ;; |
| 33 | ;; Written by Howard Gayle. |
| 34 | ;; This hack is mainly to show off the char table stuff. |
| 35 | |
| 36 | ;;; Code: |
| 37 | |
| 38 | (defvar rot13-display-table |
| 39 | (let ((table (make-display-table)) |
| 40 | (i 0)) |
| 41 | (while (< i 26) |
| 42 | (aset table (+ i ?a) (vector (+ (% (+ i 13) 26) ?a))) |
| 43 | (aset table (+ i ?A) (vector (+ (% (+ i 13) 26) ?A))) |
| 44 | (setq i (1+ i))) |
| 45 | table) |
| 46 | "Char table for rot 13 display.") |
| 47 | |
| 48 | ;;;###autoload |
| 49 | (defun rot13-other-window () |
| 50 | "Display current buffer in rot 13 in another window. |
| 51 | To terminate the rot13 display, delete that window." |
| 52 | (interactive) |
| 53 | (let ((w (display-buffer (current-buffer) t))) |
| 54 | (set-window-display-table w rot13-display-table))) |
| 55 | |
| 56 | ;;;###autoload |
| 57 | (defun toggle-rot13-mode () |
| 58 | "Toggle the use of rot 13 encoding for the current window." |
| 59 | (interactive) |
| 60 | (if (eq (window-display-table (selected-window)) rot13-display-table) |
| 61 | (set-window-display-table (selected-window) nil) |
| 62 | (if (null (window-display-table (selected-window))) |
| 63 | (set-window-display-table (selected-window) rot13-display-table)))) |
| 64 | |
| 65 | (provide 'rot13) |
| 66 | |
| 67 | ;;; rot13.el ends here |