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74 lines
2.5 KiB
EmacsLisp
74 lines
2.5 KiB
EmacsLisp
;;; rot13.el --- display a buffer in rot13
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;; Copyright (C) 1988 Free Software Foundation, Inc.
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;; Author: Howard Gayle
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;; Maintainer: FSF
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to the
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;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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;; Boston, MA 02111-1307, USA.
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;;; Commentary:
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;; The single entry point, `rot13-other-window', performs a Caesar cipher
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;; encrypt/decrypt on the current buffer and displays the result in another
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;; window. Rot13 encryption is sometimes used on USENET as a read-at-your-
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;; own-risk wrapper for material some might consider offensive, such as
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;; ethnic humor.
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;;
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;; Written by Howard Gayle.
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;; This hack is mainly to show off the char table stuff.
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;;; Code:
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(defvar rot13-display-table
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(let ((table (make-display-table))
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(i 0))
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(while (< i 26)
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(aset table (+ i ?a) (vector (+ (% (+ i 13) 26) ?a)))
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(aset table (+ i ?A) (vector (+ (% (+ i 13) 26) ?A)))
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(setq i (1+ i)))
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table)
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"Char table for rot 13 display.")
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;;;###autoload
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(defun rot13-other-window ()
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"Display current buffer in rot 13 in another window.
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The text itself is not modified, only the way it is displayed is affected.
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To terminate the rot13 display, delete that window. As long as that window
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is not deleted, any buffer displayed in it will become instantly encoded
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in rot 13.
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See also `toggle-rot13-mode'."
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(interactive)
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(let ((w (display-buffer (current-buffer) t)))
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(set-window-display-table w rot13-display-table)))
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;;;###autoload
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(defun toggle-rot13-mode ()
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"Toggle the use of rot 13 encoding for the current window."
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(interactive)
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(if (eq (window-display-table (selected-window)) rot13-display-table)
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(set-window-display-table (selected-window) nil)
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(if (null (window-display-table (selected-window)))
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(set-window-display-table (selected-window) rot13-display-table))))
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(provide 'rot13)
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;;; rot13.el ends here
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