lisp/gnus/rfc1843.el

   1 ;;; rfc1843.el --- HZ (rfc1843) decoding
   2 ;; Copyright (c) 1998, 1999, 2000 Free Software Foundation, Inc.
   3
   4 ;; Author: Shenghuo Zhu <zsh@cs.rochester.edu>
   5 ;; Keywords: news HZ HZ+ mail i18n
   6
   7 ;; This file is a part of GNU Emacs.
   8
   9 ;; GNU Emacs is free software; you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published
  11 ;; by the Free Software Foundation; either version 2, or (at your
  12 ;; option) any later version.
  13
  14 ;; GNU Emacs is distributed in the hope that it will be useful, but
  15 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17 ;; General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  21 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  22 ;; Boston, MA 02111-1307, USA.
  23
  24 ;;; Commentary:
  25
  26 ;; Usage:
  27 ;; (require 'rfc1843)
  28 ;; (rfc1843-gnus-setup)
  29 ;;
  30 ;; Test:
  31 ;; (rfc1843-decode-string  "~{<:Ky2;S{#,NpJ)l6HK!#~}")
  32
  33 ;;; Code:
  34
  35 (eval-when-compile (require 'cl))
  36 (require 'mm-util)
  37
  38 (defvar rfc1843-word-regexp
  39   "~\\({\\([\041-\167][\041-\176]\\| \\)+\\)\\(~}\\|$\\)")
  40
  41 (defvar rfc1843-word-regexp-strictly
  42   "~\\({\\([\041-\167][\041-\176]\\)+\\)\\(~}\\|$\\)")
  43
  44 (defvar rfc1843-hzp-word-regexp
  45   "~\\({\\([\041-\167][\041-\176]\\| \\)+\\|\
  46 [<>]\\([\041-\175][\041-\176]\\| \\)+\\)\\(~}\\|$\\)")
  47
  48 (defvar rfc1843-hzp-word-regexp-strictly
  49   "~\\({\\([\041-\167][\041-\176]\\)+\\|\
  50 [<>]\\([\041-\175][\041-\176]\\)+\\)\\(~}\\|$\\)")
  51
  52 (defcustom rfc1843-decode-loosely nil
  53   "Loosely check HZ encoding if non-nil.
  54 When it is set non-nil, only buffers or strings with strictly
  55 HZ-encoded are decoded."
  56   :type 'boolean
  57   :group 'gnus)
  58
  59 (defcustom rfc1843-decode-hzp t
  60   "HZ+ decoding support if non-nil.
  61 HZ+ specification (also known as HZP) is to provide a standardized
  62 7-bit representation of mixed Big5, GB, and ASCII text for convenient
  63 e-mail transmission, news posting, etc.
  64 The document of HZ+ 0.78 specification can be found at
  65 ftp://ftp.math.psu.edu/pub/simpson/chinese/hzp/hzp.doc"
  66   :type 'boolean
  67   :group 'gnus)
  68
  69 (defcustom rfc1843-newsgroups-regexp "chinese\\|hz"
  70   "Regexp of newsgroups in which might be HZ encoded."
  71   :type 'string
  72   :group 'gnus)
  73
  74 (defun rfc1843-decode-region (from to)
  75   "Decode HZ in the region between FROM and TO."
  76   (interactive "r")
  77   (let (str firstc)
  78     (save-excursion
  79       (goto-char from)
  80       (if (or rfc1843-decode-loosely
  81               (re-search-forward (if rfc1843-decode-hzp
  82                                      rfc1843-hzp-word-regexp-strictly
  83                                    rfc1843-word-regexp-strictly) to t))
  84           (save-restriction
  85             (narrow-to-region from to)
  86             (goto-char (point-min))
  87             (while (re-search-forward (if rfc1843-decode-hzp
  88                                           rfc1843-hzp-word-regexp
  89                                         rfc1843-word-regexp) (point-max) t)
  90               ;;; Text with extents may cause XEmacs crash
  91               (setq str (buffer-substring-no-properties
  92                          (match-beginning 1)
  93                          (match-end 1)))
  94               (setq firstc (aref str 0))
  95               (insert (mm-decode-coding-string
  96                        (rfc1843-decode
  97                         (prog1
  98                             (substring str 1)
  99                           (delete-region (match-beginning 0) (match-end 0)))
 100                         firstc)
 101                        (if (eq firstc ?{) 'cn-gb-2312 'cn-big5))))
 102             (goto-char (point-min))
 103             (while (search-forward "~" (point-max) t)
 104               (cond ((eq (char-after) ?\n)
 105                      (delete-char -1)
 106                      (delete-char 1))
 107                     ((eq (char-after) ?~)
 108                      (delete-char 1)))))))))
 109
 110 (defun rfc1843-decode-string (string)
 111   "Decode HZ STRING and return the results."
 112   (let ((m (mm-multibyte-p)))
 113     (with-temp-buffer
 114       (when m
 115         (mm-enable-multibyte))
 116       (insert string)
 117       (inline
 118         (rfc1843-decode-region (point-min) (point-max)))
 119       (buffer-string))))
 120
 121 (defun rfc1843-decode (word &optional firstc)
 122   "Decode HZ WORD and return it."
 123   (let ((i -1) (s (substring word 0)) v)
 124     (if (or (not firstc) (eq firstc ?{))
 125         (while (< (incf i) (length s))
 126           (if (eq (setq v (aref s i)) ? ) nil
 127             (aset s i (+ 128 v))))
 128       (while (< (incf i) (length s))
 129         (if (eq (setq v (aref s i)) ? ) nil
 130           (setq v (+ (* 94 v) (aref s (1+ i)) -3135))
 131           (aset s i (+ (/ v 157) (if (eq firstc ?<) 201 161)))
 132           (setq v (% v 157))
 133           (aset s (incf i) (+ v (if (< v 63) 64 98))))))
 134     s))
 135
 136 (defun rfc1843-decode-article-body ()
 137   "Decode HZ encoded text in the article body."
 138   (if (string-match (concat "\\<\\(" rfc1843-newsgroups-regexp "\\)\\>")
 139                     (or gnus-newsgroup-name ""))
 140       (save-excursion
 141         (save-restriction
 142           (message-narrow-to-head)
 143           (let* ((inhibit-point-motion-hooks t)
 144                  (case-fold-search t)
 145                  (ct (message-fetch-field "Content-Type" t))
 146                  (ctl (and ct (ignore-errors
 147                                 (mail-header-parse-content-type ct)))))
 148             (if (and ctl (not (string-match "/" (car ctl))))
 149                 (setq ctl nil))
 150             (goto-char (point-max))
 151             (widen)
 152             (forward-line 1)
 153             (narrow-to-region (point) (point-max))
 154             (when (or (not ctl)
 155                       (equal (car ctl) "text/plain"))
 156               (rfc1843-decode-region (point) (point-max))))))))
 157
 158 (defvar rfc1843-old-gnus-decode-header-function  nil)
 159 (defvar gnus-decode-header-methods)
 160 (defvar gnus-decode-encoded-word-methods)
 161
 162 (defun rfc1843-gnus-setup ()
 163   "Setup HZ decoding for Gnus."
 164   (require 'gnus-art)
 165   (require 'gnus-sum)
 166   (add-hook 'gnus-article-decode-hook 'rfc1843-decode-article-body t)
 167   (setq gnus-decode-encoded-word-function
 168         'gnus-multi-decode-encoded-word-string
 169         gnus-decode-header-function
 170         'gnus-multi-decode-header
 171         gnus-decode-encoded-word-methods
 172         (nconc gnus-decode-encoded-word-methods
 173                (list
 174                 (cons (concat "\\<\\(" rfc1843-newsgroups-regexp "\\)\\>")
 175                       'rfc1843-decode-string)))
 176         gnus-decode-header-methods
 177         (nconc gnus-decode-header-methods
 178                (list
 179                 (cons (concat "\\<\\(" rfc1843-newsgroups-regexp "\\)\\>")
 180                       'rfc1843-decode-region)))))
 181
 182 (provide 'rfc1843)
 183
 184 ;;; rfc1843.el ends here