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Diffstat (limited to 'lisp/international/rfc1843.el')
| -rw-r--r-- | lisp/international/rfc1843.el | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/lisp/international/rfc1843.el b/lisp/international/rfc1843.el new file mode 100644 index 00000000000..c1343274c93 --- /dev/null +++ b/lisp/international/rfc1843.el @@ -0,0 +1,131 @@ +;;; rfc1843.el --- HZ (rfc1843) decoding + +;; Copyright (C) 1998-2017 Free Software Foundation, Inc. + +;; Author: Shenghuo Zhu <zsh@cs.rochester.edu> +;; Keywords: news HZ HZ+ mail i18n + +;; This file is part of GNU Emacs. + +;; GNU Emacs 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 3 of the License, or +;; (at your option) any later version. + +;; GNU Emacs 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. If not, see <http://www.gnu.org/licenses/>. + +;;; Commentary: + +;; Test: +;; (rfc1843-decode-string "~{<:Ky2;S{#,NpJ)l6HK!#~}") + +;;; Code: + +(eval-when-compile (require 'cl)) + +(defvar rfc1843-word-regexp + "~\\({\\([\041-\167][\041-\176]\\| \\)+\\)\\(~}\\|$\\)") + +(defvar rfc1843-word-regexp-strictly + "~\\({\\([\041-\167][\041-\176]\\)+\\)\\(~}\\|$\\)") + +(defvar rfc1843-hzp-word-regexp + "~\\({\\([\041-\167][\041-\176]\\| \\)+\\|\ +[<>]\\([\041-\175][\041-\176]\\| \\)+\\)\\(~}\\|$\\)") + +(defvar rfc1843-hzp-word-regexp-strictly + "~\\({\\([\041-\167][\041-\176]\\)+\\|\ +[<>]\\([\041-\175][\041-\176]\\)+\\)\\(~}\\|$\\)") + +(defcustom rfc1843-decode-loosely nil + "Loosely check HZ encoding if non-nil. +When it is set non-nil, only buffers or strings with strictly +HZ-encoded are decoded." + :type 'boolean + :group 'mime) + +(defcustom rfc1843-decode-hzp t + "HZ+ decoding support if non-nil. +HZ+ specification (also known as HZP) is to provide a standardized +7-bit representation of mixed Big5, GB, and ASCII text for convenient +e-mail transmission, news posting, etc. +The document of HZ+ 0.78 specification can be found at +ftp://ftp.math.psu.edu/pub/simpson/chinese/hzp/hzp.doc" + :type 'boolean + :group 'mime) + +(defcustom rfc1843-newsgroups-regexp "chinese\\|hz" + "Regexp of newsgroups in which might be HZ encoded." + :type 'string + :group 'mime) + +(defun rfc1843-decode-region (from to) + "Decode HZ in the region between FROM and TO." + (interactive "r") + (let (str firstc) + (save-excursion + (goto-char from) + (if (or rfc1843-decode-loosely + (re-search-forward (if rfc1843-decode-hzp + rfc1843-hzp-word-regexp-strictly + rfc1843-word-regexp-strictly) to t)) + (save-restriction + (narrow-to-region from to) + (goto-char (point-min)) + (while (re-search-forward (if rfc1843-decode-hzp + rfc1843-hzp-word-regexp + rfc1843-word-regexp) (point-max) t) + (setq str (buffer-substring-no-properties + (match-beginning 1) + (match-end 1))) + (setq firstc (aref str 0)) + (insert (decode-coding-string + (rfc1843-decode + (prog1 + (substring str 1) + (delete-region (match-beginning 0) (match-end 0))) + firstc) + (if (eq firstc ?{) 'cn-gb-2312 'cn-big5)))) + (goto-char (point-min)) + (while (search-forward "~" (point-max) t) + (cond ((eq (char-after) ?\n) + (delete-char -1) + (delete-char 1)) + ((eq (char-after) ?~) + (delete-char 1))))))))) + +(defun rfc1843-decode-string (string) + "Decode HZ STRING and return the results." + (let ((m enable-multibyte-characters)) + (with-temp-buffer + (when m + (set-buffer-multibyte 'to)) + (insert string) + (inline + (rfc1843-decode-region (point-min) (point-max))) + (buffer-string)))) + +(defun rfc1843-decode (word &optional firstc) + "Decode HZ WORD and return it." + (let ((i -1) (s (substring word 0)) v) + (if (or (not firstc) (eq firstc ?{)) + (while (< (incf i) (length s)) + (if (eq (setq v (aref s i)) ? ) nil + (aset s i (+ 128 v)))) + (while (< (incf i) (length s)) + (if (eq (setq v (aref s i)) ? ) nil + (setq v (+ (* 94 v) (aref s (1+ i)) -3135)) + (aset s i (+ (/ v 157) (if (eq firstc ?<) 201 161))) + (setq v (% v 157)) + (aset s (incf i) (+ v (if (< v 63) 64 98)))))) + s)) + +(provide 'rfc1843) + +;;; rfc1843.el ends here |