lisp/gnus/rfc1843.el

   1 ;;; rfc1843.el --- HZ (rfc1843) decoding
   2
   3 ;; Copyright (C) 1998, 1999, 2000, 2002, 2003, 2004,
   4 ;;   2005, 2006 Free Software Foundation, Inc.
   5
   6 ;; Author: Shenghuo Zhu <zsh@cs.rochester.edu>
   7 ;; Keywords: news HZ HZ+ mail i18n
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published
  13 ;; by the Free Software Foundation; either version 2, or (at your
  14 ;; option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful, but
  17 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19 ;; General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  24 ;; Boston, MA 02110-1301, USA.
  25
  26 ;;; Commentary:
  27
  28 ;; Usage:
  29 ;; (require 'rfc1843)
  30 ;; (rfc1843-gnus-setup)
  31 ;;
  32 ;; Test:
  33 ;; (rfc1843-decode-string  "~{<:Ky2;S{#,NpJ)l6HK!#~}")
  34
  35 ;;; Code:
  36
  37 (eval-when-compile (require 'cl))
  38 (require 'mm-util)
  39
  40 (defvar gnus-decode-encoded-word-function)
  41 (defvar gnus-decode-header-function)
  42 (defvar gnus-newsgroup-name)
  43
  44 (defvar rfc1843-word-regexp
  45   "~\\({\\([\041-\167][\041-\176]\\| \\)+\\)\\(~}\\|$\\)")
  46
  47 (defvar rfc1843-word-regexp-strictly
  48   "~\\({\\([\041-\167][\041-\176]\\)+\\)\\(~}\\|$\\)")
  49
  50 (defvar rfc1843-hzp-word-regexp
  51   "~\\({\\([\041-\167][\041-\176]\\| \\)+\\|\
  52 \[<>]\\([\041-\175][\041-\176]\\| \\)+\\)\\(~}\\|$\\)")
  53
  54 (defvar rfc1843-hzp-word-regexp-strictly
  55   "~\\({\\([\041-\167][\041-\176]\\)+\\|\
  56 \[<>]\\([\041-\175][\041-\176]\\)+\\)\\(~}\\|$\\)")
  57
  58 (defcustom rfc1843-decode-loosely nil
  59   "Loosely check HZ encoding if non-nil.
  60 When it is set non-nil, only buffers or strings with strictly
  61 HZ-encoded are decoded."
  62   :type 'boolean
  63   :group 'mime)
  64
  65 (defcustom rfc1843-decode-hzp t
  66   "HZ+ decoding support if non-nil.
  67 HZ+ specification (also known as HZP) is to provide a standardized
  68 7-bit representation of mixed Big5, GB, and ASCII text for convenient
  69 e-mail transmission, news posting, etc.
  70 The document of HZ+ 0.78 specification can be found at
  71 ftp://ftp.math.psu.edu/pub/simpson/chinese/hzp/hzp.doc"
  72   :type 'boolean
  73   :group 'mime)
  74
  75 (defcustom rfc1843-newsgroups-regexp "chinese\\|hz"
  76   "Regexp of newsgroups in which might be HZ encoded."
  77   :type 'string
  78   :group 'mime)
  79
  80 (defun rfc1843-decode-region (from to)
  81   "Decode HZ in the region between FROM and TO."
  82   (interactive "r")
  83   (let (str firstc)
  84     (save-excursion
  85       (goto-char from)
  86       (if (or rfc1843-decode-loosely
  87               (re-search-forward (if rfc1843-decode-hzp
  88                                      rfc1843-hzp-word-regexp-strictly
  89                                    rfc1843-word-regexp-strictly) to t))
  90           (save-restriction
  91             (narrow-to-region from to)
  92             (goto-char (point-min))
  93             (while (re-search-forward (if rfc1843-decode-hzp
  94                                           rfc1843-hzp-word-regexp
  95                                         rfc1843-word-regexp) (point-max) t)
  96               ;;; Text with extents may cause XEmacs crash
  97               (setq str (buffer-substring-no-properties
  98                          (match-beginning 1)
  99                          (match-end 1)))
 100               (setq firstc (aref str 0))
 101               (insert (mm-decode-coding-string
 102                        (rfc1843-decode
 103                         (prog1
 104                             (substring str 1)
 105                           (delete-region (match-beginning 0) (match-end 0)))
 106                         firstc)
 107                        (if (eq firstc ?{) 'cn-gb-2312 'cn-big5))))
 108             (goto-char (point-min))
 109             (while (search-forward "~" (point-max) t)
 110               (cond ((eq (char-after) ?\n)
 111                      (delete-char -1)
 112                      (delete-char 1))
 113                     ((eq (char-after) ?~)
 114                      (delete-char 1)))))))))
 115
 116 (defun rfc1843-decode-string (string)
 117   "Decode HZ STRING and return the results."
 118   (let ((m (mm-multibyte-p)))
 119     (with-temp-buffer
 120       (when m
 121         (mm-enable-multibyte))
 122       (insert string)
 123       (inline
 124         (rfc1843-decode-region (point-min) (point-max)))
 125       (buffer-string))))
 126
 127 (defun rfc1843-decode (word &optional firstc)
 128   "Decode HZ WORD and return it."
 129   (let ((i -1) (s (substring word 0)) v)
 130     (if (or (not firstc) (eq firstc ?{))
 131         (while (< (incf i) (length s))
 132           (if (eq (setq v (aref s i)) ? ) nil
 133             (aset s i (+ 128 v))))
 134       (while (< (incf i) (length s))
 135         (if (eq (setq v (aref s i)) ? ) nil
 136           (setq v (+ (* 94 v) (aref s (1+ i)) -3135))
 137           (aset s i (+ (/ v 157) (if (eq firstc ?<) 201 161)))
 138           (setq v (% v 157))
 139           (aset s (incf i) (+ v (if (< v 63) 64 98))))))
 140     s))
 141
 142 (defun rfc1843-decode-article-body ()
 143   "Decode HZ encoded text in the article body."
 144   (if (string-match (concat "\\<\\(" rfc1843-newsgroups-regexp "\\)\\>")
 145                     (or gnus-newsgroup-name ""))
 146       (save-excursion
 147         (save-restriction
 148           (message-narrow-to-head)
 149           (let* ((inhibit-point-motion-hooks t)
 150                  (case-fold-search t)
 151                  (ct (message-fetch-field "Content-Type" t))
 152                  (ctl (and ct (mail-header-parse-content-type ct))))
 153             (if (and ctl (not (string-match "/" (car ctl))))
 154                 (setq ctl nil))
 155             (goto-char (point-max))
 156             (widen)
 157             (forward-line 1)
 158             (narrow-to-region (point) (point-max))
 159             (when (or (not ctl)
 160                       (equal (car ctl) "text/plain"))
 161               (rfc1843-decode-region (point) (point-max))))))))
 162
 163 (defvar rfc1843-old-gnus-decode-header-function  nil)
 164 (defvar gnus-decode-header-methods)
 165 (defvar gnus-decode-encoded-word-methods)
 166
 167 (defun rfc1843-gnus-setup ()
 168   "Setup HZ decoding for Gnus."
 169   (require 'gnus-art)
 170   (require 'gnus-sum)
 171   (add-hook 'gnus-article-decode-hook 'rfc1843-decode-article-body t)
 172   (setq gnus-decode-encoded-word-function
 173         'gnus-multi-decode-encoded-word-string
 174         gnus-decode-header-function
 175         'gnus-multi-decode-header
 176         gnus-decode-encoded-word-methods
 177         (nconc gnus-decode-encoded-word-methods
 178                (list
 179                 (cons (concat "\\<\\(" rfc1843-newsgroups-regexp "\\)\\>")
 180                       'rfc1843-decode-string)))
 181         gnus-decode-header-methods
 182         (nconc gnus-decode-header-methods
 183                (list
 184                 (cons (concat "\\<\\(" rfc1843-newsgroups-regexp "\\)\\>")
 185                       'rfc1843-decode-region)))))
 186
 187 (provide 'rfc1843)
 188
 189 ;;; arch-tag: 5149c301-a6ca-4731-9c9d-ba616e2cb687
 190 ;;; rfc1843.el ends here