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;;; mule-caesar.el --- ROT 13-47 Caesar rotation utility -*- lexical-binding: t -*-
;; Copyright (C) 1997,1998 Free Software Foundation, Inc.
;; Author: MORIOKA Tomohiko <morioka@jaist.ac.jp>
;; Keywords: ROT 13-47, caesar, mail, news, text/x-rot13-47
;; This file is part of APEL (A Portable Emacs Library).
;; This program is free software; you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation; either version 2, or (at
;; your option) any later version.
;; This program is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
;;; Code:
(defun mule-caesar-region (start end &optional stride-ascii)
"Caesar rotation of current region.
Optional argument STRIDE-ASCII is rotation-size for Latin alphabet
(A-Z and a-z). For non-ASCII text, ROT-N/2 will be performed in any
case (N=charset-chars; 94 for 94 or 94x94 graphic character set; 96
for 96 or 96x96 graphic character set)."
(interactive "r\nP")
(setq stride-ascii (if stride-ascii
(mod stride-ascii 26)
13))
(save-excursion
(save-restriction
(narrow-to-region start end)
(goto-char start)
(while (< (point)(point-max))
(let* ((chr (following-char)))
(cond ((and (<= ?A chr) (<= chr ?Z))
(setq chr (+ chr stride-ascii))
(if (> chr ?Z)
(setq chr (- chr 26))
)
(delete-char 1)
(insert chr)
)
((and (<= ?a chr) (<= chr ?z))
(setq chr (+ chr stride-ascii))
(if (> chr ?z)
(setq chr (- chr 26))
)
(delete-char 1)
(insert chr)
)
((<= chr ?\x9f)
(forward-char)
)
(t
(let* ((stride (lsh (charset-chars (char-charset chr)) -1))
(ret (mapcar (lambda (octet)
(if (< octet 80)
(+ octet stride)
(- octet stride)
))
(cdr (split-char chr)))))
(delete-char 1)
(insert (make-char (char-charset chr)
(car ret)(car (cdr ret))))
)))
)))))
(require 'product)
(product-provide (provide 'mule-caesar) (require 'apel-ver))
;;; mule-caesar.el ends here
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