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;; china-util.el -- utilities for Chinese
;; Copyright (C) 1995 Free Software Foundation, Inc.
;; Copyright (C) 1995 Electrotechnical Laboratory, JAPAN.
;; Keywords: mule, multilingual, Chinese
;; 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 2, 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; see the file COPYING. If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
;;; Code:
;; Hz/ZW encoding stuffs
;; HZ is an encoding method for Chinese character set GB2312 used
;; widely in Internet. It is very similar to 7-bit environment of
;; ISO-2022. The difference is that HZ uses the sequence "~{" and
;; "~}" for designating GB2312 and ASCII respectively, hence, it
;; doesn't uses ESC (0x1B) code.
;; ZW is another encoding method for Chinese character set GB2312. It
;; encodes Chinese characters line by line by starting each line with
;; the sequence "zW". It also uses only 7-bit as HZ.
;; ISO-2022 escape sequence to designate GB2312.
(defvar iso2022-gb-designation "\e$A")
;; HZ escape sequence to designate GB2312.
(defvar hz-gb-designnation "~{")
;; ISO-2022 escape sequence to designate ASCII.
(defvar iso2022-ascii-designation "\e(B")
;; HZ escape sequence to designate ASCII.
(defvar hz-ascii-designnation "~}")
;; Regexp of ZW sequence to start GB2312.
(defvar zw-start-gb "^zW")
;; Regexp for start of GB2312 in an encoding mixture of HZ and ZW.
(defvar hz/zw-start-gb (concat hz-gb-designnation "\\|" zw-start-gb))
(defvar decode-hz-line-continuation nil
"Flag to tell if we should care line continuation convention of Hz.")
;;;###autoload
(defun decode-hz-region (beg end)
"Decode HZ/ZW encoded text in the current region.
Return the length of resulting text."
(interactive "r")
(save-excursion
(save-restriction
(narrow-to-region beg end)
;; We, at first, convert HZ/ZW to `coding-system-iso-2022-7',
;; then decode it.
;; "~\n" -> "\n"
(goto-char (point-min))
(while (search-forward "~" nil t)
(if (= (following-char) ?\n) (delete-char -1))
(if (not (eobp)) (forward-char 1)))
;; "^zW...\n" -> Chinese GB2312
;; "~{...~}" -> Chinese GB2312
(goto-char (point-min))
(let ((chinese-found nil))
(while (re-search-forward hz/zw-start-gb nil t)
(if (= (char-after (match-beginning 0)) ?z)
;; ZW -> coding-system-iso-20227-7
(progn
(delete-char -2)
(insert iso2022-gb-designation)
(end-of-line)
(insert iso2022-ascii-designation))
;; HZ -> coding-system-iso-20227-7
(delete-char -2)
(insert iso2022-gb-designation)
(let ((pos (save-excursion (end-of-line) (point))))
(if (search-forward hz-ascii-designnation pos t)
(replace-match iso2022-ascii-designation)
(if (not decode-hz-line-continuation)
(insert iso2022-ascii-designation)))))
(setq chinese-found t))
(if (or chinese-found
(let ((enable-multibyte-characters nil))
;; Here we check if the text contains EUC (China) codes.
;; If any, we had better decode them also.
(goto-char (point-min))
(re-search-forward "[\240-\377]" nil t)))
(decode-coding-region (point-min) (point-max)
'coding-system-euc-china)))
;; "~~" -> "~"
(goto-char (point-min))
(while (search-forward "~~" nil t) (delete-char -1))
(- (point-max) (point-min)))))
;;;###autoload
(defun decode-hz-buffer ()
"Decode HZ/ZW encoded text in the current buffer."
(interactive)
(decode-hz-region (point-min) (point-max)))
;;;###autoload
(defun encode-hz-region (beg end)
"Encode the text in the current region to HZ.
Return the length of resulting text."
(interactive "r")
(save-excursion
(save-restriction
(narrow-to-region beg end)
;; "~" -> "~~"
(goto-char (point-min))
(while (search-forward "~" nil t) (insert ?~))
;; Chinese GB2312 -> "~{...~}"
(goto-char (point-min))
(if (re-search-forward "\\cc" nil t)
(let ((enable-multibyte-characters nil)
pos)
(goto-char (setq pos (match-beginning 0)))
(encode-coding-region pos (point-max) 'coding-system-iso-2022-7)
(goto-char pos)
(while (search-forward iso2022-gb-designation nil t)
(delete-char -3)
(insert hz-gb-designnation))
(goto-char pos)
(while (search-forward iso2022-ascii-designation nil t)
(delete-char -3)
(insert hz-ascii-designnation))))
(- (point-max) (point-min)))))
;;;###autoload
(defun encode-hz-buffer ()
"Encode the text in the current buffer to HZ."
(interactive)
(encode-hz-region (point-min) (point-max)))
;;
(provide 'language/china-util)
;;; Local Variables:
;;; generated-autoload-file: "../loaddefs.el"
;;; End:
;;; china-util.el ends here
|
