code.delx.au - gnu-emacs/blob - lisp/international/utf-8.el

   1 ;;; utf-8.el --- UTF-8 decoding/encoding support -*- coding: iso-2022-7bit -*-
   2
   3 ;; Copyright (C) 2001, 2004 Electrotechnical Laboratory, JAPAN.
   4 ;; Licensed to the Free Software Foundation.
   5 ;; Copyright (C) 2001, 2002 Free Software Foundation, Inc.
   6
   7 ;; Author: TAKAHASHI Naoto  <ntakahas@m17n.org>
   8 ;; Maintainer: FSF
   9 ;; Keywords: multilingual, Unicode, UTF-8, i18n
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software; you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation; either version 2, or (at your option)
  16 ;; any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  25 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  26 ;; Boston, MA 02111-1307, USA.
  27
  28 ;;; Commentary:
  29
  30 ;; The coding-system `mule-utf-8' basically supports encoding/decoding
  31 ;; of the following character sets to and from UTF-8:
  32 ;;
  33 ;;   ascii
  34 ;;   eight-bit-control
  35 ;;   latin-iso8859-1
  36 ;;   mule-unicode-0100-24ff
  37 ;;   mule-unicode-2500-33ff
  38 ;;   mule-unicode-e000-ffff
  39 ;;
  40 ;; On decoding, Unicode characters that do not fit into the above
  41 ;; character sets are handled as `eight-bit-control' or
  42 ;; `eight-bit-graphic' characters to retain the information about the
  43 ;; original byte sequence and text properties record the corresponding
  44 ;; unicode.
  45 ;;
  46 ;; Fixme: note that reading and writing invalid utf-8 may not be
  47 ;; idempotent -- to represent the bytes to fix that needs a new charset.
  48 ;;
  49 ;; Characters from other character sets can be encoded with mule-utf-8
  50 ;; by populating the translation table
  51 ;; `utf-translation-table-for-encode'.  Hash tables
  52 ;; `utf-subst-table-for-decode' and `utf-subst-table-for-encode' are
  53 ;; used to support encoding and decoding of about a quarter of the CJK
  54 ;; space between U+3400 and U+DFFF.
  55
  56 ;; UTF-8 is defined in RFC 3629.  A sketch of the encoding is:
  57
  58 ;;        scalar       |               utf-8
  59 ;;        value        | 1st byte  | 2nd byte  | 3rd byte
  60 ;; --------------------+-----------+-----------+----------
  61 ;; 0000 0000 0xxx xxxx | 0xxx xxxx |           |
  62 ;; 0000 0yyy yyxx xxxx | 110y yyyy | 10xx xxxx |
  63 ;; zzzz yyyy yyxx xxxx | 1110 zzzz | 10yy yyyy | 10xx xxxx
  64
  65 ;;; Code:
  66
  67 (defvar ucs-mule-to-mule-unicode (make-char-table 'translation-table nil)
  68   "Char table mapping characters to latin-iso8859-1 or mule-unicode-*.
  69
  70 If `unify-8859-on-encoding-mode' is non-nil, this table populates the
  71 translation-table named `utf-translation-table-for-encode'.")
  72
  73 (define-translation-table 'utf-translation-table-for-encode)
  74
  75
  76 ;; Map Cyrillic and Greek to iso-8859 charsets, which take half the
  77 ;; space of mule-unicode.  For Latin scripts this isn't very
  78 ;; important.  Hebrew and Arabic might go here too when there's proper
  79 ;; support for them.
  80
  81 (defvar utf-fragmentation-table (make-char-table 'translation-table nil)
  82   "Char-table normally mapping non-Latin mule-unicode-* chars to iso-8859-*.
  83
  84 If `utf-fragment-on-decoding' is non-nil, this table populates the
  85 translation-table named `utf-translation-table-for-decode'")
  86
  87 (defvar utf-defragmentation-table (make-char-table 'translation-table nil)
  88   "Char-table for reverse mapping of `utf-fragmentation-table'.
  89
  90 If `utf-fragment-on-decoding' is non-nil and
  91 `unify-8859-on-encoding-mode' is nil, this table populates the
  92 translation-table named `utf-translation-table-for-encode'")
  93
  94 (define-translation-table 'utf-translation-table-for-decode)
  95
  96
  97 (defvar ucs-mule-cjk-to-unicode (make-hash-table :test 'eq)
  98   "Hash table mapping Emacs CJK character sets to Unicode code points.
  99
 100 If `utf-translate-cjk-mode' is non-nil, this table populates the
 101 translation-hash-table named `utf-subst-table-for-encode'.")
 102
 103 (define-translation-hash-table 'utf-subst-table-for-encode
 104   ucs-mule-cjk-to-unicode)
 105
 106 (defvar ucs-unicode-to-mule-cjk (make-hash-table :test 'eq)
 107   "Hash table mapping Unicode code points to Emacs CJK character sets.
 108
 109 If `utf-translate-cjk-mode' is non-nil, this table populates the
 110 translation-hash-table named `utf-subst-table-for-decode'.")
 111
 112 (define-translation-hash-table 'utf-subst-table-for-decode
 113   ucs-unicode-to-mule-cjk)
 114
 115 (mapc
 116  (lambda (pair)
 117    (aset utf-fragmentation-table (car pair) (cdr pair))
 118    (aset utf-defragmentation-table (cdr pair) (car pair)))
 119  '((?\e$,1&d\e(B . ?\e,F4\e(B) (?\e$,1&e\e(B . ?\e,F5\e(B) (?\e$,1&f\e(B . ?\e,F6\e(B) (?\e$,1&h\e(B . ?\e,F8\e(B) (?\e$,1&i\e(B . ?\e,F9\e(B)
 120    (?\e$,1&j\e(B . ?\e,F:\e(B) (?\e$,1&l\e(B . ?\e,F<\e(B) (?\e$,1&n\e(B . ?\e,F>\e(B) (?\e$,1&o\e(B . ?\e,F?\e(B) (?\e$,1&p\e(B . ?\e,F@\e(B)
 121    (?\e$,1&q\e(B . ?\e,FA\e(B) (?\e$,1&r\e(B . ?\e,FB\e(B) (?\e$,1&s\e(B . ?\e,FC\e(B) (?\e$,1&t\e(B . ?\e,FD\e(B) (?\e$,1&u\e(B . ?\e,FE\e(B)
 122    (?\e$,1&v\e(B . ?\e,FF\e(B) (?\e$,1&w\e(B . ?\e,FG\e(B) (?\e$,1&x\e(B . ?\e,FH\e(B) (?\e$,1&y\e(B . ?\e,FI\e(B) (?\e$,1&z\e(B . ?\e,FJ\e(B)
 123    (?\e$,1&{\e(B . ?\e,FK\e(B) (?\e$,1&|\e(B . ?\e,FL\e(B) (?\e$,1&}\e(B . ?\e,FM\e(B) (?\e$,1&~\e(B . ?\e,FN\e(B) (?\e$,1&\7f\e(B . ?\e,FO\e(B)
 124    (?\e$,1' \e(B . ?\e,FP\e(B) (?\e$,1'!\e(B . ?\e,FQ\e(B) (?\e$,1'#\e(B . ?\e,FS\e(B) (?\e$,1'$\e(B . ?\e,FT\e(B) (?\e$,1'%\e(B . ?\e,FU\e(B)
 125    (?\e$,1'&\e(B . ?\e,FV\e(B) (?\e$,1''\e(B . ?\e,FW\e(B) (?\e$,1'(\e(B . ?\e,FX\e(B) (?\e$,1')\e(B . ?\e,FY\e(B) (?\e$,1'*\e(B . ?\e,FZ\e(B)
 126    (?\e$,1'+\e(B . ?\e,F[\e(B) (?\e$,1',\e(B . ?\e,F\\e(B) (?\e$,1'-\e(B . ?\e,F]\e(B) (?\e$,1'.\e(B . ?\e,F^\e(B) (?\e$,1'/\e(B . ?\e,F_\e(B)
 127    (?\e$,1'0\e(B . ?\e,F`\e(B) (?\e$,1'1\e(B . ?\e,Fa\e(B) (?\e$,1'2\e(B . ?\e,Fb\e(B) (?\e$,1'3\e(B . ?\e,Fc\e(B) (?\e$,1'4\e(B . ?\e,Fd\e(B)
 128    (?\e$,1'5\e(B . ?\e,Fe\e(B) (?\e$,1'6\e(B . ?\e,Ff\e(B) (?\e$,1'7\e(B . ?\e,Fg\e(B) (?\e$,1'8\e(B . ?\e,Fh\e(B) (?\e$,1'9\e(B . ?\e,Fi\e(B)
 129    (?\e$,1':\e(B . ?\e,Fj\e(B) (?\e$,1';\e(B . ?\e,Fk\e(B) (?\e$,1'<\e(B . ?\e,Fl\e(B) (?\e$,1'=\e(B . ?\e,Fm\e(B) (?\e$,1'>\e(B . ?\e,Fn\e(B)
 130    (?\e$,1'?\e(B . ?\e,Fo\e(B) (?\e$,1'@\e(B . ?\e,Fp\e(B) (?\e$,1'A\e(B . ?\e,Fq\e(B) (?\e$,1'B\e(B . ?\e,Fr\e(B) (?\e$,1'C\e(B . ?\e,Fs\e(B)
 131    (?\e$,1'D\e(B . ?\e,Ft\e(B) (?\e$,1'E\e(B . ?\e,Fu\e(B) (?\e$,1'F\e(B . ?\e,Fv\e(B) (?\e$,1'G\e(B . ?\e,Fw\e(B) (?\e$,1'H\e(B . ?\e,Fx\e(B)
 132    (?\e$,1'I\e(B . ?\e,Fy\e(B) (?\e$,1'J\e(B . ?\e,Fz\e(B) (?\e$,1'K\e(B . ?\e,F{\e(B) (?\e$,1'L\e(B . ?\e,F|\e(B) (?\e$,1'M\e(B . ?\e,F}\e(B)
 133    (?\e$,1'N\e(B . ?\e,F~\e(B)
 134
 135    (?\e$,1(!\e(B . ?\e,L!\e(B) (?\e$,1("\e(B . ?\e,L"\e(B) (?\e$,1(#\e(B . ?\e,L#\e(B) (?\e$,1($\e(B . ?\e,L$\e(B)
 136    (?\e$,1(%\e(B . ?\e,L%\e(B) (?\e$,1(&\e(B . ?\e,L&\e(B) (?\e$,1('\e(B . ?\e,L'\e(B) (?\e$,1((\e(B . ?\e,L(\e(B) (?\e$,1()\e(B . ?\e,L)\e(B)
 137    (?\e$,1(*\e(B . ?\e,L*\e(B) (?\e$,1(+\e(B . ?\e,L+\e(B) (?\e$,1(,\e(B . ?\e,L,\e(B) (?\e$,1(.\e(B . ?\e,L.\e(B) (?\e$,1(/\e(B . ?\e,L/\e(B)
 138    (?\e$,1(0\e(B . ?\e,L0\e(B) (?\e$,1(1\e(B . ?\e,L1\e(B) (?\e$,1(2\e(B . ?\e,L2\e(B) (?\e$,1(3\e(B . ?\e,L3\e(B) (?\e$,1(4\e(B . ?\e,L4\e(B)
 139    (?\e$,1(5\e(B . ?\e,L5\e(B) (?\e$,1(6\e(B . ?\e,L6\e(B) (?\e$,1(7\e(B . ?\e,L7\e(B) (?\e$,1(8\e(B . ?\e,L8\e(B) (?\e$,1(9\e(B . ?\e,L9\e(B)
 140    (?\e$,1(:\e(B . ?\e,L:\e(B) (?\e$,1(;\e(B . ?\e,L;\e(B) (?\e$,1(<\e(B . ?\e,L<\e(B) (?\e$,1(=\e(B . ?\e,L=\e(B) (?\e$,1(>\e(B . ?\e,L>\e(B)
 141    (?\e$,1(?\e(B . ?\e,L?\e(B) (?\e$,1(@\e(B . ?\e,L@\e(B) (?\e$,1(A\e(B . ?\e,LA\e(B) (?\e$,1(B\e(B . ?\e,LB\e(B) (?\e$,1(C\e(B . ?\e,LC\e(B)
 142    (?\e$,1(D\e(B . ?\e,LD\e(B) (?\e$,1(E\e(B . ?\e,LE\e(B) (?\e$,1(F\e(B . ?\e,LF\e(B) (?\e$,1(G\e(B . ?\e,LG\e(B) (?\e$,1(H\e(B . ?\e,LH\e(B)
 143    (?\e$,1(I\e(B . ?\e,LI\e(B) (?\e$,1(J\e(B . ?\e,LJ\e(B) (?\e$,1(K\e(B . ?\e,LK\e(B) (?\e$,1(L\e(B . ?\e,LL\e(B) (?\e$,1(M\e(B . ?\e,LM\e(B)
 144    (?\e$,1(N\e(B . ?\e,LN\e(B) (?\e$,1(O\e(B . ?\e,LO\e(B) (?\e$,1(P\e(B . ?\e,LP\e(B) (?\e$,1(Q\e(B . ?\e,LQ\e(B) (?\e$,1(R\e(B . ?\e,LR\e(B)
 145    (?\e$,1(S\e(B . ?\e,LS\e(B) (?\e$,1(T\e(B . ?\e,LT\e(B) (?\e$,1(U\e(B . ?\e,LU\e(B) (?\e$,1(V\e(B . ?\e,LV\e(B) (?\e$,1(W\e(B . ?\e,LW\e(B)
 146    (?\e$,1(X\e(B . ?\e,LX\e(B) (?\e$,1(Y\e(B . ?\e,LY\e(B) (?\e$,1(Z\e(B . ?\e,LZ\e(B) (?\e$,1([\e(B . ?\e,L[\e(B) (?\e$,1(\\e(B . ?\e,L\\e(B)
 147    (?\e$,1(]\e(B . ?\e,L]\e(B) (?\e$,1(^\e(B . ?\e,L^\e(B) (?\e$,1(_\e(B . ?\e,L_\e(B) (?\e$,1(`\e(B . ?\e,L`\e(B) (?\e$,1(a\e(B . ?\e,La\e(B)
 148    (?\e$,1(b\e(B . ?\e,Lb\e(B) (?\e$,1(c\e(B . ?\e,Lc\e(B) (?\e$,1(d\e(B . ?\e,Ld\e(B) (?\e$,1(e\e(B . ?\e,Le\e(B) (?\e$,1(f\e(B . ?\e,Lf\e(B)
 149    (?\e$,1(g\e(B . ?\e,Lg\e(B) (?\e$,1(h\e(B . ?\e,Lh\e(B) (?\e$,1(i\e(B . ?\e,Li\e(B) (?\e$,1(j\e(B . ?\e,Lj\e(B) (?\e$,1(k\e(B . ?\e,Lk\e(B)
 150    (?\e$,1(l\e(B . ?\e,Ll\e(B) (?\e$,1(m\e(B . ?\e,Lm\e(B) (?\e$,1(n\e(B . ?\e,Ln\e(B) (?\e$,1(o\e(B . ?\e,Lo\e(B) (?\e$,1(q\e(B . ?\e,Lq\e(B)
 151    (?\e$,1(r\e(B . ?\e,Lr\e(B) (?\e$,1(s\e(B . ?\e,Ls\e(B) (?\e$,1(t\e(B . ?\e,Lt\e(B) (?\e$,1(u\e(B . ?\e,Lu\e(B) (?\e$,1(v\e(B . ?\e,Lv\e(B)
 152    (?\e$,1(w\e(B . ?\e,Lw\e(B) (?\e$,1(x\e(B . ?\e,Lx\e(B) (?\e$,1(y\e(B . ?\e,Ly\e(B) (?\e$,1(z\e(B . ?\e,Lz\e(B) (?\e$,1({\e(B . ?\e,L{\e(B)
 153    (?\e$,1(|\e(B . ?\e,L|\e(B) (?\e$,1(~\e(B . ?\e,L~\e(B) (?\e$,1(\7f\e(B . ?\e,L\7f\e(B)))
 154
 155
 156 (defcustom utf-fragment-on-decoding nil
 157   "Whether or not to decode some chars in UTF-8/16 text into iso8859 charsets.
 158 Setting this means that the relevant Cyrillic and Greek characters are
 159 decoded into the iso8859 charsets rather than into
 160 mule-unicode-0100-24ff.  The iso8859 charsets take half as much space
 161 in the buffer, but using them may affect how the buffer can be re-encoded
 162 and may require a different input method to search for them, for instance.
 163 See `unify-8859-on-decoding-mode' and `unify-8859-on-encoding-mode'
 164 for mechanisms to make this largely transparent.
 165
 166 Setting this variable outside customize has no effect."
 167   :set (lambda (s v)
 168          (if v
 169              (progn
 170                (define-translation-table 'utf-translation-table-for-decode
 171                  utf-fragmentation-table)
 172                ;; Even if unify-8859-on-encoding-mode is off, make
 173                ;; mule-utf-* encode characters in
 174                ;; utf-fragmentation-table.
 175                (unless (eq (get 'utf-translation-table-for-encode
 176                                 'translation-table)
 177                            ucs-mule-to-mule-unicode)
 178                  (define-translation-table 'utf-translation-table-for-encode
 179                    utf-defragmentation-table)))
 180            (define-translation-table 'utf-translation-table-for-decode)
 181            ;; When unify-8859-on-encoding-mode is off, be sure to make
 182            ;; mule-utf-* disabled for characters in
 183            ;; utf-fragmentation-table.
 184            (unless (eq (get 'utf-translation-table-for-encode
 185                             'translation-table)
 186                        ucs-mule-to-mule-unicode)
 187              (define-translation-table 'utf-translation-table-for-encode)))
 188          (set-default s v))
 189   :version "21.4"
 190   :type 'boolean
 191   :group 'mule)
 192
 193
 194 (defconst utf-translate-cjk-charsets '(chinese-gb2312
 195                                        chinese-big5-1 chinese-big5-2
 196                                        japanese-jisx0208 japanese-jisx0212
 197                                        korean-ksc5601)
 198   "List of charsets supported by `utf-translate-cjk-mode'.")
 199
 200 (defconst utf-translate-cjk-unicode-range
 201   '((#x2e80 . #xd7a3)
 202     (#xff00 . #xffef))
 203   "List of Unicode code ranges supported by `utf-translate-cjk-mode'.")
 204
 205 ;; Return non-nil if CODE-POINT is in `utf-translate-cjk-unicode-range'.
 206 (defsubst utf-translate-cjk-substitutable-p (code-point)
 207   (let ((tail utf-translate-cjk-unicode-range)
 208         elt)
 209     (while tail
 210       (setq elt (car tail) tail (cdr tail))
 211       (if (and (>= code-point (car elt)) (<= code-point (cdr elt)))
 212           (setq tail nil)
 213         (setq elt nil)))
 214     elt))
 215
 216 (defvar utf-translate-cjk-lang-env nil
 217   "Language environment in which tables for `utf-translate-cjk-mode' is loaded.
 218 The value nil means that the tables are not yet loaded.")
 219
 220 (defun utf-translate-cjk-load-tables ()
 221   "Load tables for `utf-translate-cjk-mode'."
 222   ;; Fixme: Allow the use of the CJK charsets to be
 223   ;; customized by reordering and possible omission.
 224   (let ((redefined (< (hash-table-size ucs-mule-cjk-to-unicode) 43000)))
 225     (if redefined
 226         ;; Redefine them with realistic initial sizes and a
 227         ;; smallish rehash size to avoid wasting significant
 228         ;; space after they're built.
 229         (setq ucs-mule-cjk-to-unicode
 230               (make-hash-table :test 'eq :size 43000 :rehash-size 1000)
 231               ucs-unicode-to-mule-cjk
 232               (make-hash-table :test 'eq :size 21500 :rehash-size 1000)))
 233
 234     ;; Load the files explicitly, to avoid having to keep
 235     ;; around the large tables they contain (as well as the
 236     ;; ones which get built).
 237     (cond ((string= "Korean" current-language-environment)
 238            (load "subst-jis")
 239            (load "subst-big5")
 240            (load "subst-gb2312")
 241            (load "subst-ksc"))
 242           ((string= "Chinese-BIG5" current-language-environment)
 243            (load "subst-jis")
 244            (load "subst-ksc")
 245            (load "subst-gb2312")
 246            (load "subst-big5"))
 247           ((string= "Chinese-GB" current-language-environment)
 248            (load "subst-jis")
 249            (load "subst-ksc")
 250            (load "subst-big5")
 251            (load "subst-gb2312"))
 252           (t
 253            (load "subst-ksc")
 254            (load "subst-gb2312")
 255            (load "subst-big5")
 256            (load "subst-jis")))   ; jis covers as much as big5, gb2312
 257
 258     (when redefined
 259       (define-translation-hash-table 'utf-subst-table-for-decode
 260         ucs-unicode-to-mule-cjk)
 261       (define-translation-hash-table 'utf-subst-table-for-encode
 262         ucs-mule-cjk-to-unicode)
 263       (set-char-table-extra-slot (get 'utf-translation-table-for-encode
 264                                       'translation-table)
 265                                  1 ucs-mule-cjk-to-unicode))
 266
 267     (setq utf-translate-cjk-lang-env current-language-environment)))
 268
 269 (defun utf-lookup-subst-table-for-decode (code-point)
 270   (if (and utf-translate-cjk-mode
 271            (not utf-translate-cjk-lang-env)
 272            (utf-translate-cjk-substitutable-p code-point))
 273       (utf-translate-cjk-load-tables))
 274   (gethash code-point
 275            (get 'utf-subst-table-for-decode 'translation-hash-table)))
 276
 277
 278 (defun utf-lookup-subst-table-for-encode (char)
 279   (if (and utf-translate-cjk-mode
 280            (not utf-translate-cjk-lang-env)
 281            (memq (char-charset char) utf-translate-cjk-charsets))
 282       (utf-translate-cjk-load-tables))
 283   (gethash char
 284            (get 'utf-subst-table-for-encode 'translation-hash-table)))
 285
 286 (define-minor-mode utf-translate-cjk-mode
 287   "Whether the UTF based coding systems should decode/encode CJK characters.
 288 Enabling this allows the coding systems mule-utf-8,
 289 mule-utf-16le and mule-utf-16be to encode characters in the charsets
 290 `korean-ksc5601', `chinese-gb2312', `chinese-big5-1',
 291 `chinese-big5-2', `japanese-jisx0208' and `japanese-jisx0212', and to
 292 decode the corresponding unicodes into such characters.
 293
 294 Where the charsets overlap, the one preferred for decoding is chosen
 295 according to the language environment in effect when this option is
 296 turned on: ksc5601 for Korean, gb2312 for Chinese-GB, big5 for
 297 Chinese-Big5 and jisx for other environments.
 298
 299 This option is on by default.  If you are not interested in CJK
 300 characters and want to avoid some overhead on encoding/decoding
 301 by the above coding systems, you can customize this option to nil."
 302   :init-value t
 303   :version "21.4"
 304   :type 'boolean
 305   :group 'mule
 306   :global t
 307   (if utf-translate-cjk-mode
 308       (progn
 309         (define-translation-hash-table 'utf-subst-table-for-decode
 310           ucs-unicode-to-mule-cjk)
 311         (define-translation-hash-table 'utf-subst-table-for-encode
 312           ucs-mule-cjk-to-unicode)
 313         (set-char-table-extra-slot (get 'utf-translation-table-for-encode
 314                                         'translation-table)
 315                                    1 ucs-mule-cjk-to-unicode))
 316     (define-translation-hash-table 'utf-subst-table-for-decode
 317       (make-hash-table :test 'eq))
 318     (define-translation-hash-table 'utf-subst-table-for-encode
 319       (make-hash-table :test 'eq))
 320     (set-char-table-extra-slot (get 'utf-translation-table-for-encode
 321                                     'translation-table)
 322                                1 nil))
 323
 324   ;; Update safe-chars of mule-utf-* coding systems.
 325   (dolist (elt (coding-system-list t))
 326     (if (string-match "^mule-utf" (symbol-name elt))
 327         (let ((safe-charsets (coding-system-get elt 'safe-charsets))
 328               (safe-chars (coding-system-get elt 'safe-chars))
 329               (need-update nil))
 330           (dolist (charset utf-translate-cjk-charsets)
 331             (unless (eq utf-translate-cjk-mode (memq charset safe-charsets))
 332               (setq safe-charsets
 333                     (if utf-translate-cjk-mode
 334                         (cons charset safe-charsets)
 335                       (delq charset safe-charsets))
 336                     need-update t)
 337               (aset safe-chars (make-char charset) utf-translate-cjk-mode)))
 338           (when need-update
 339             (coding-system-put elt 'safe-charsets safe-charsets)
 340             (define-coding-system-internal elt))))))
 341
 342 (define-ccl-program ccl-mule-utf-untrans
 343   ;; R0 is an untranslatable Unicode code-point (U+3500..U+DFFF or
 344   ;; U+10000..U+10FFFF) or an invaid byte (#x00..#xFF).  Write
 345   ;; eight-bit-control/graphic sequence (2 to 4 chars) representing
 346   ;; UTF-8 sequence of r0.  Registers r4, r5, r6 are modified.
 347   ;;
 348   ;; This is a subrountine because we assume that this is called very
 349   ;; rarely (so we don't have to worry about the overhead of the
 350   ;; call).
 351   `(0
 352     ((r5 = ,(charset-id 'eight-bit-control))
 353      (r6 = ,(charset-id 'eight-bit-graphic))
 354      (if (r0 < #x100)
 355          ((r4 = ((r0 >> 6) | #xC0))
 356           (write-multibyte-character r6 r4))
 357        ((if (r0 < #x10000)
 358             ((r4 = ((r0 >> 12) | #xE0))
 359              (write-multibyte-character r6 r4))
 360           ((r4 = ((r0 >> 18) | #xF0))
 361            (write-multibyte-character r6 r4)
 362            (r4 = (((r0 >> 12) & #x3F) | #x80))
 363            (if (r4 < #xA0)
 364                (write-multibyte-character r5 r4)
 365              (write-multibyte-character r6 r4))))
 366         (r4 = (((r0 >> 6) & #x3F) | #x80))
 367         (if (r4 < #xA0)
 368             (write-multibyte-character r5 r4)
 369           (write-multibyte-character r6 r4))))
 370      (r4 = ((r0 & #x3F) | #x80))
 371      (if (r4 < #xA0)
 372          (write-multibyte-character r5 r4)
 373        (write-multibyte-character r6 r4)))))
 374
 375 (define-ccl-program ccl-decode-mule-utf-8
 376   ;;
 377   ;;        charset         | bytes in utf-8 | bytes in emacs
 378   ;; -----------------------+----------------+---------------
 379   ;;         ascii          |       1        |       1
 380   ;; -----------------------+----------------+---------------
 381   ;;    eight-bit-control   |       2        |       2
 382   ;;    eight-bit-graphic   |       2        |       1
 383   ;;     latin-iso8859-1    |       2        |       2
 384   ;; -----------------------+----------------+---------------
 385   ;; mule-unicode-0100-24ff |       2        |       4
 386   ;;        (< 0800)        |                |
 387   ;; -----------------------+----------------+---------------
 388   ;; mule-unicode-0100-24ff |       3        |       4
 389   ;;        (>= 8000)       |                |
 390   ;; mule-unicode-2500-33ff |       3        |       4
 391   ;; mule-unicode-e000-ffff |       3        |       4
 392   ;; -----------------------+----------------+---------------
 393   ;;      invalid byte      |       1        |       2
 394   ;;
 395   ;; Thus magnification factor is two.
 396   ;;
 397   `(2
 398     ((r6 = ,(charset-id 'latin-iso8859-1))
 399      (read r0)
 400      (loop
 401       (if (r0 < #x80)
 402           ;; 1-byte encoding, i.e., ascii
 403           (write-read-repeat r0))
 404       (if (r0 < #xc2)
 405           ;; continuation byte (invalid here) or 1st byte of overlong
 406           ;; 2-byte sequence.
 407           ((call ccl-mule-utf-untrans)
 408            (r6 = ,(charset-id 'latin-iso8859-1))
 409            (read r0)
 410            (repeat)))
 411
 412       ;; Read the 2nd byte.
 413       (read r1)
 414       (if ((r1 & #b11000000) != #b10000000) ; Invalid 2nd byte
 415           ((call ccl-mule-utf-untrans)
 416            (r6 = ,(charset-id 'latin-iso8859-1))
 417            ;; Handle it in the next loop.
 418            (r0 = r1)
 419            (repeat)))
 420
 421       (if (r0 < #xe0)
 422           ;; 2-byte encoding 00000yyyyyxxxxxx = 110yyyyy 10xxxxxx
 423           ((r1 &= #x3F)
 424            (r1 |= ((r0 & #x1F) << 6))
 425            ;; Now r2 holds scalar value.  We don't have to check
 426            ;; `overlong sequence' because r0 >= 0xC2.
 427
 428            (if (r1 >= 256)
 429                ;; mule-unicode-0100-24ff (< 0800)
 430                ((r0 = ,(charset-id 'mule-unicode-0100-24ff))
 431                 (r1 -= #x0100)
 432                 (r2 = (((r1 / 96) + 32) << 7))
 433                 (r1 %= 96)
 434                 (r1 += (r2 + 32))
 435                 (translate-character
 436                  utf-translation-table-for-decode r0 r1)
 437                 (write-multibyte-character r0 r1)
 438                 (read r0)
 439                 (repeat))
 440              (if (r1 >= 160)
 441                  ;; latin-iso8859-1
 442                  ((r1 -= 128)
 443                   (write-multibyte-character r6 r1)
 444                   (read r0)
 445                   (repeat))
 446                ;; eight-bit-control
 447                ((r0 = ,(charset-id 'eight-bit-control))
 448                 (write-multibyte-character r0 r1)
 449                 (read r0)
 450                 (repeat))))))
 451
 452       ;; Read the 3rd bytes.
 453       (read r2)
 454       (if ((r2 & #b11000000) != #b10000000) ; Invalid 3rd byte
 455           ((call ccl-mule-utf-untrans)
 456            (r0 = r1)
 457            (call ccl-mule-utf-untrans)
 458            (r6 = ,(charset-id 'latin-iso8859-1))
 459            ;; Handle it in the next loop.
 460            (r0 = r2)
 461            (repeat)))
 462
 463       (if (r0 < #xF0)
 464           ;; 3byte encoding
 465           ;; zzzzyyyyyyxxxxxx = 1110zzzz 10yyyyyy 10xxxxxx
 466           ((r3 = ((r0 & #xF) << 12))
 467            (r3 |= ((r1 & #x3F) << 6))
 468            (r3 |= (r2 & #x3F))
 469
 470            (if (r3 < #x800)             ; `overlong sequence'
 471                ((call ccl-mule-utf-untrans)
 472                 (r0 = r1)
 473                 (call ccl-mule-utf-untrans)
 474                 (r0 = r2)
 475                 (call ccl-mule-utf-untrans)
 476                 (r6 = ,(charset-id 'latin-iso8859-1))
 477                 (read r0)
 478                 (repeat)))
 479
 480            (if (r3 < #x2500)
 481                ;; mule-unicode-0100-24ff (>= 0800)
 482                ((r0 = ,(charset-id 'mule-unicode-0100-24ff))
 483                 (r3 -= #x0100)
 484                 (r3 //= 96)
 485                 (r1 = (r7 + 32))
 486                 (r1 += ((r3 + 32) << 7))
 487                 (translate-character
 488                  utf-translation-table-for-decode r0 r1)
 489                 (write-multibyte-character r0 r1)
 490                 (read r0)
 491                 (repeat)))
 492
 493            (if (r3 < #x3400)
 494                ;; mule-unicode-2500-33ff
 495                ((r0 = r3)               ; don't zap r3
 496                 (lookup-integer utf-subst-table-for-decode r0 r1)
 497                 (if (r7 == 0)
 498                     ((r0 = ,(charset-id 'mule-unicode-2500-33ff))
 499                      (r3 -= #x2500)
 500                      (r3 //= 96)
 501                      (r1 = (r7 + 32))
 502                      (r1 += ((r3 + 32) << 7))))
 503                 (write-multibyte-character r0 r1)
 504                 (read r0)
 505                 (repeat)))
 506
 507            (if (r3 < #xE000)
 508                ;; Try to convert to CJK chars, else
 509                ;; keep them as eight-bit-{control|graphic}.
 510                ((r0 = r3)
 511                 (lookup-integer utf-subst-table-for-decode r3 r1)
 512                 (if r7
 513                     ;; got a translation
 514                     ((write-multibyte-character r3 r1)
 515                      (read r0)
 516                      (repeat))
 517                   ((call ccl-mule-utf-untrans)
 518                    (r6 = ,(charset-id 'latin-iso8859-1))
 519                    (read r0)
 520                    (repeat)))))
 521
 522            ;; mule-unicode-e000-ffff
 523            ;; Fixme: fffe and ffff are invalid.
 524            (r0 = r3)            ; don't zap r3
 525            (lookup-integer utf-subst-table-for-decode r0 r1)
 526            (if (r7 == 0)
 527                ((r0 = ,(charset-id 'mule-unicode-e000-ffff))
 528                 (r3 -= #xe000)
 529                 (r3 //= 96)
 530                 (r1 = (r7 + 32))
 531                 (r1 += ((r3 + 32) << 7))))
 532            (write-multibyte-character r0 r1)
 533            (read r0)
 534            (repeat)))
 535
 536       ;; Read the 4th bytes.
 537       (read r3)
 538       (if ((r3 & #b11000000) != #b10000000) ; Invalid 4th byte
 539           ((call ccl-mule-utf-untrans)
 540            (r0 = r1)
 541            (call ccl-mule-utf-untrans)
 542            (r0 = r2)
 543            (call ccl-mule-utf-untrans)
 544            (r6 = ,(charset-id 'latin-iso8859-1))
 545            ;; Handle it in the next loop.
 546            (r0 = r3)
 547            (repeat)))
 548
 549       (if (r0 < #xF8)
 550           ;; 4-byte encoding:
 551           ;; wwwzzzzzzyyyyyyxxxxxx = 11110www 10zzzzzz 10yyyyyy 10xxxxxx
 552           ;; keep those bytes as eight-bit-{control|graphic}
 553           ;; Fixme: allow lookup in utf-subst-table-for-decode.
 554           ((r4 = ((r0 & #x7) << 18))
 555            (r4 |= ((r1 & #x3F) << 12))
 556            (r4 |= ((r2 & #x3F) << 6))
 557            (r4 |= (r3 & #x3F))
 558
 559            (if (r4 < #x10000)           ; `overlong sequence'
 560                ((call ccl-mule-utf-untrans)
 561                 (r0 = r1)
 562                 (call ccl-mule-utf-untrans)
 563                 (r0 = r2)
 564                 (call ccl-mule-utf-untrans)
 565                 (r0 = r3)
 566                 (call ccl-mule-utf-untrans))
 567              ((r0 = r4)
 568               (call ccl-mule-utf-untrans))))
 569
 570         ;; Unsupported sequence.
 571         ((call ccl-mule-utf-untrans)
 572          (r0 = r1)
 573          (call ccl-mule-utf-untrans)
 574          (r0 = r2)
 575          (call ccl-mule-utf-untrans)
 576          (r0 = r3)
 577          (call ccl-mule-utf-untrans)))
 578       (r6 = ,(charset-id 'latin-iso8859-1))
 579       (read r0)
 580       (repeat)))
 581
 582
 583     ;; At EOF...
 584     (if (r0 >= 0)
 585         ;; r0 >= #x80
 586         ((call ccl-mule-utf-untrans)
 587          (if (r1 >= 0)
 588              ((r0 = r1)
 589               (call ccl-mule-utf-untrans)
 590               (if (r2 >= 0)
 591                   ((r0 = r2)
 592                    (call ccl-mule-utf-untrans)
 593                    (if (r3 >= 0)
 594                        ((r0 = r3)
 595                         (call ccl-mule-utf-untrans))))))))))
 596
 597   "CCL program to decode UTF-8.
 598 Basic decoding is done into the charsets ascii, latin-iso8859-1 and
 599 mule-unicode-*, but see also `utf-fragmentation-table' and
 600 `ucs-mule-cjk-to-unicode'.
 601 Encodings of un-representable Unicode characters are decoded asis into
 602 eight-bit-control and eight-bit-graphic characters.")
 603
 604 (define-ccl-program ccl-mule-utf-8-encode-untrans
 605   ;; UTF-8 decoder generates an UTF-8 sequence represented by a
 606   ;; sequence eight-bit-control/graphic chars for an untranslatable
 607   ;; character and an invalid byte.
 608   ;;
 609   ;; This CCL parses that sequence (the first byte is already in r1),
 610   ;; writes out the original bytes of that sequence, and sets r5 to
 611   ;; -1.
 612   ;;
 613   ;; If the eight-bit-control/graphic sequence is shorter than what r1
 614   ;; suggests, it sets r5 and r6 to the last character read that
 615   ;; should be handled by the next loop of a caller.
 616   ;;
 617   ;; Note: For UTF-8 validation, we only check if a character is
 618   ;; eight-bit-control/graphic or not.  It may result in incorrect
 619   ;; handling of random binary data, but such a data can't be encoded
 620   ;; by UTF-8 anyway.  At least, UTF-8 decoders doesn't generate such
 621   ;; a sequence even if a source contains invalid byte-sequence.
 622   `(0
 623     (;; Read the 2nd byte.
 624      (read-multibyte-character r5 r6)
 625      (r0 = (r5 != ,(charset-id 'eight-bit-control)))
 626      (if ((r5 != ,(charset-id 'eight-bit-graphic)) & r0)
 627          ((write r1)                    ; invalid UTF-8
 628           (r1 = -1)
 629           (end)))
 630
 631      (if (r1 <= #xC3)
 632          ;; 2-byte sequence for an originally invalid byte.
 633          ((r6 &= #x3F)
 634           (r6 |= ((r1 & #x1F) << 6))
 635           (write r6)
 636           (r5 = -1)
 637           (end)))
 638
 639      (write r1 r6)
 640      (r2 = r1)
 641      (r1 = -1)
 642      ;; Read the 3rd byte.
 643      (read-multibyte-character r5 r6)
 644      (r0 = (r5 != ,(charset-id 'eight-bit-control)))
 645      (if ((r5 != ,(charset-id 'eight-bit-graphic)) & r0)
 646          (end))                         ; invalid UTF-8
 647      (write r6)
 648      (if (r2 < #xF0)
 649          ;; 3-byte sequence for an untranslated character.
 650          ((r5 = -1)
 651           (end)))
 652      ;; Read the 4th byte.
 653      (read-multibyte-character r5 r6)
 654      (r0 = (r5 != ,(charset-id 'eight-bit-control)))
 655      (if ((r5 != ,(charset-id 'eight-bit-graphic)) & r0)
 656          (end))                 ; invalid UTF-8
 657      ;; 4-byte sequence for an untranslated character.
 658      (write r6)
 659      (r5 = -1)
 660      (end))
 661
 662     ;; At EOF...
 663     ((r5 = -1)
 664      (if (r1 >= 0)
 665          (write r1)))))
 666
 667 (define-ccl-program ccl-encode-mule-utf-8
 668   `(1
 669     ((r5 = -1)
 670      (loop
 671       (if (r5 < 0)
 672           (read-multibyte-character r0 r1)
 673         ;; Pre-read character is in r5 (charset-ID) and r6 (code-point).
 674         ((r0 = r5)
 675          (r1 = r6)
 676          (r5 = -1)))
 677       (translate-character utf-translation-table-for-encode r0 r1)
 678
 679       (if (r0 == ,(charset-id 'ascii))
 680           (write-repeat r1))
 681
 682       (if (r0 == ,(charset-id 'latin-iso8859-1))
 683           ;; r1          scalar                  utf-8
 684           ;;       0000 0yyy yyxx xxxx    110y yyyy 10xx xxxx
 685           ;; 20    0000 0000 1010 0000    1100 0010 1010 0000
 686           ;; 7f    0000 0000 1111 1111    1100 0011 1011 1111
 687           ((r0 = (((r1 & #x40) >> 6) | #xc2))
 688            (r1 &= #x3f)
 689            (r1 |= #x80)
 690            (write r0)
 691            (write-repeat r1)))
 692
 693       (if (r0 == ,(charset-id 'mule-unicode-0100-24ff))
 694           ((r0 = ((((r1 & #x3f80) >> 7) - 32) * 96))
 695            ;; #x3f80 == (0011 1111 1000 0000)b
 696            (r1 &= #x7f)
 697            (r1 += (r0 + 224))           ; 240 == -32 + #x0100
 698            ;; now r1 holds scalar value
 699            (if (r1 < #x0800)
 700                ;; 2byte encoding
 701                ((write ((r1 >> 6) | #xC0))
 702                 (r1 &= #x3F)
 703                 (r1 |= #x80)
 704                 (write-repeat r1))
 705              ;; 3byte encoding
 706              ((write ((r1 >> 12) | #xE0))
 707               (write  (((r1 & #x0FC0) >> 6) | #x80))
 708               (r1 &= #x3F)
 709               (r1 |= #x80)
 710               (write-repeat r1)))))
 711
 712       (if (r0 == ,(charset-id 'mule-unicode-2500-33ff))
 713           ((r0 = ((((r1 & #x3f80) >> 7) - 32) * 96))
 714            (r1 &= #x7f)
 715            (r1 += (r0 + 9440))          ; 9440 == -32 + #x2500
 716            ;; now r1 holds scalar value
 717            (write ((r1 >> 12) | #xE0))
 718            (write  (((r1 & #x0FC0) >> 6) | #x80))
 719            (r1 &= #x3F)
 720            (r1 |= #x80)
 721            (write-repeat r1)))
 722
 723       (if (r0 == ,(charset-id 'mule-unicode-e000-ffff))
 724           ((r0 = ((((r1 & #x3f80) >> 7) - 32) * 96))
 725            (r1 &= #x7f)
 726            (r1 += (r0 + 57312))         ; 57312 == -32 + #xe000
 727            ;; now r1 holds scalar value
 728            (write ((r1 >> 12) | #xE0))
 729            (write  (((r1 & #x0FC0) >> 6) | #x80))
 730            (r1 &= #x3F)
 731            (r1 |= #x80)
 732            (write-repeat r1)))
 733
 734       (if (r0 == ,(charset-id 'eight-bit-control))
 735           ;; r1          scalar                  utf-8
 736           ;;       0000 0yyy yyxx xxxx    110y yyyy 10xx xxxx
 737           ;; 80    0000 0000 1000 0000    1100 0010 1000 0000
 738           ;; 9f    0000 0000 1001 1111    1100 0010 1001 1111
 739           ((write #xC2)
 740            (write-repeat r1)))
 741
 742       (if (r0 == ,(charset-id 'eight-bit-graphic))
 743           ;; r1          scalar                  utf-8
 744           ;;       0000 0yyy yyxx xxxx    110y yyyy 10xx xxxx
 745           ;; a0    0000 0000 1010 0000    1100 0010 1010 0000
 746           ;; ff    0000 0000 1111 1111    1101 1111 1011 1111
 747           ((r0 = (r1 >= #xC0))
 748            (r0 &= (r1 <= #xC3))
 749            (r4 = (r1 >= #xE1))
 750            (r4 &= (r1 <= #xF7))
 751            (r0 |= r4)
 752            (if r0
 753                ((call ccl-mule-utf-8-encode-untrans)
 754                 (repeat))
 755              (write-repeat r1))))
 756
 757       (lookup-character utf-subst-table-for-encode r0 r1)
 758       (if r7            ; lookup succeeded
 759           (if (r0 < #x800)
 760               ;; 2byte encoding
 761               ((write ((r0 >> 6) | #xC0))
 762                (r1 &= #x3F)
 763                (r1 |= #x80)
 764                (write-repeat r1))
 765             ;; 3byte encoding
 766             ((write ((r0 >> 12) | #xE0))
 767              (write  (((r0 & #x0FC0) >> 6) | #x80))
 768              (r1 &= #x3F)
 769              (r1 |= #x80)
 770              (write-repeat r1))))
 771
 772       ;; Unsupported character.
 773       ;; Output U+FFFD, which is `ef bf bd' in UTF-8.
 774       (write #xef)
 775       (write #xbf)
 776       (write-repeat #xbd))))
 777   "CCL program to encode into UTF-8.")
 778
 779
 780 (define-ccl-program ccl-untranslated-to-ucs
 781   `(0
 782     (if (r1 == 0)
 783         nil
 784       (if (r0 <= #xC3)                  ; 2-byte encoding
 785           ((r0 = ((r0 & #x3) << 6))
 786            (r0 |= (r1 & #x3F))
 787            (r1 = 2))
 788         (if (r2 == 0)
 789             (r1 = 0)
 790           (if (r0 < #xF0)               ; 3-byte encoding, as above
 791               ((r0 = ((r0 & #xF) << 12))
 792                (r0 |= ((r1 & #x3F) << 6))
 793                (r0 |= (r2 & #x3F))
 794                (r1 = 3))
 795             (if (r3 == 0)
 796                 (r1 = 0)
 797               ((r0 = ((r0 & #x7) << 18))
 798                (r0 |= ((r1 & #x3F) << 12))
 799                (r0 |= ((r2 & #x3F) << 6))
 800                (r0 |= (r3 & #x3F))
 801                (r1 = 4))))))))
 802   "Decode 2-, 3-, or 4-byte sequences in r0, r1, r2 [,r3] to unicodes in r0.
 803 Set r1 to the byte length.  r0 == 0 for invalid sequence.")
 804
 805 (defvar utf-8-ccl-regs (make-vector 8 0))
 806
 807 (defsubst utf-8-untranslated-to-ucs ()
 808   "Return the UCS code for an untranslated sequence of raw bytes t point.
 809 Only for 3- or 4-byte sequences."
 810   (aset utf-8-ccl-regs 0 (or (char-after) 0))
 811   (aset utf-8-ccl-regs 1 (or (char-after (1+ (point))) 0))
 812   (aset utf-8-ccl-regs 2 (or (char-after (+ 2 (point))) 0))
 813   (aset utf-8-ccl-regs 3 (or (char-after (+ 3 (point))) 0))
 814   (ccl-execute 'ccl-untranslated-to-ucs utf-8-ccl-regs))
 815
 816 (defun utf-8-help-echo (window object position)
 817   (format "Untranslated Unicode U+%04X"
 818           (get-char-property position 'untranslated-utf-8 object)))
 819
 820 ;; We compose the untranslatable sequences into a single character,
 821 ;; and move point to the next character.
 822 ;; This is infelicitous for editing, because there's currently no
 823 ;; mechanism for treating compositions as atomic, but is OK for
 824 ;; display.  They are composed to U+FFFD with help-echo which
 825 ;; indicates the unicodes they represent.  This function GCs too much.
 826
 827 ;; If utf-translate-cjk-mode is non-nil, this function is called with
 828 ;; HASH-TABLE which translates CJK characters into some of CJK
 829 ;; charsets.
 830
 831 (defsubst utf-8-compose (hash-table)
 832   "Put a suitable composition on an untranslatable sequence at point.
 833 If HASH-TABLE is non-nil, try to translate CJK characters by it at first.
 834 Move point to the end of the sequence."
 835   (utf-8-untranslated-to-ucs)
 836   (let ((l (aref utf-8-ccl-regs 1))
 837         ch)
 838     (if (> l 0)
 839         (if (and hash-table
 840                  (setq ch (gethash (aref utf-8-ccl-regs 0)  hash-table)))
 841             (progn
 842               (insert ch)
 843               (delete-region (point) (min (point-max) (+ l (point)))))
 844           (setq ch (aref utf-8-ccl-regs 0))
 845           (put-text-property (point) (min (point-max) (+ l (point)))
 846                              'untranslated-utf-8 ch)
 847           (put-text-property (point) (min (point-max) (+ l (point)))
 848                              'help-echo 'utf-8-help-echo)
 849           (if (= l 2)
 850               (put-text-property (point) (min (point-max) (+ l (point)))
 851                                  'display (format "\\%03o" ch))
 852             (compose-region (point) (+ l (point)) ?\e$,3u=\e(B))
 853           (forward-char l))
 854       (forward-char 1))))
 855
 856 (defcustom utf-8-compose-scripts nil
 857   "*Non-nil means compose various scripts on decoding utf-8 text."
 858   :group 'mule
 859   :version "21.4"
 860   :type 'boolean)
 861
 862 (defun utf-8-post-read-conversion (length)
 863   "Compose untranslated utf-8 sequences into single characters.
 864 If `utf-translate-cjk-mode' is non-nil, tries to translate CJK characters.
 865 Also compose particular scripts if `utf-8-compose-scripts' is non-nil."
 866   (save-excursion
 867     (save-restriction
 868       (narrow-to-region (point) (+ (point) length))
 869       ;; Can't do eval-when-compile to insert a multibyte constant
 870       ;; version of the string in the loop, since it's always loaded as
 871       ;; unibyte from a byte-compiled file.
 872       (let ((range (string-as-multibyte "^\xc0-\xc3\xe1-\xf7"))
 873             hash-table ch)
 874         (when utf-translate-cjk-mode
 875           (if (not utf-translate-cjk-lang-env)
 876               ;; Check these characters:
 877               ;;   "U+2e80-U+33ff", "U+ff00-U+ffef"
 878               ;; We may have to translate them to CJK charsets.
 879               (let ((range2 "\e$,29@\e(B-\e$,2G\7f\e$,3r`\e(B-\e$,3u/\e(B"))
 880                 (skip-chars-forward (concat range range2))
 881                 (unless (eobp)
 882                   (utf-translate-cjk-load-tables)
 883                   (setq range (concat range range2)))
 884           (setq hash-table (get 'utf-subst-table-for-decode
 885                                 'translation-hash-table)))))
 886         (while (and (skip-chars-forward range)
 887                     (not (eobp)))
 888           (setq ch (following-char))
 889           (if (< ch 256)
 890               (utf-8-compose hash-table)
 891             (if (and hash-table
 892                      (setq ch (gethash (encode-char ch 'ucs) hash-table)))
 893                 (progn
 894                   (insert ch)
 895                   (delete-char 1))
 896               (forward-char 1)))))
 897
 898       (when (and utf-8-compose-scripts (> length 1))
 899         ;; These currently have definitions which cover the relevant
 900         ;; unicodes.  We could avoid loading thai-util &c by checking
 901         ;; whether the region contains any characters with the appropriate
 902         ;; categories.  There aren't yet Unicode-based rules for Tibetan.
 903         (diacritic-compose-region (point-max) (point-min))
 904         (thai-compose-region (point-max) (point-min))
 905         (lao-compose-region (point-max) (point-min))
 906         (devanagari-compose-region (point-max) (point-min))
 907         (malayalam-compose-region (point-max) (point-min))
 908         (tamil-compose-region (point-max) (point-min)))
 909       (- (point-max) (point-min)))))
 910
 911 (defun utf-8-pre-write-conversion (beg end)
 912   "Prepare for `utf-translate-cjk-mode' to encode text between BEG and END.
 913 This is used as a post-read-conversion of utf-8 coding system."
 914   (if (and utf-translate-cjk-mode
 915            (not utf-translate-cjk-lang-env)
 916            (save-excursion
 917              (goto-char beg)
 918              (re-search-forward "\\cc\\|\\cj\\|\\ch" end t)))
 919       (utf-translate-cjk-load-tables))
 920   nil)
 921
 922 (make-coding-system
 923  'mule-utf-8 4 ?u
 924  "UTF-8 encoding for Emacs-supported Unicode characters.
 925 It supports Unicode characters of these ranges:
 926     U+0000..U+33FF, U+E000..U+FFFF.
 927 They correspond to these Emacs character sets:
 928     ascii, latin-iso8859-1, mule-unicode-0100-24ff,
 929     mule-unicode-2500-33ff, mule-unicode-e000-ffff
 930
 931 On decoding (e.g. reading a file), Unicode characters not in the above
 932 ranges are decoded into sequences of eight-bit-control and
 933 eight-bit-graphic characters to preserve their byte sequences.  The
 934 byte sequence is preserved on i/o for valid utf-8, but not necessarily
 935 for invalid utf-8.
 936
 937 On encoding (e.g. writing a file), Emacs characters not belonging to
 938 any of the character sets listed above are encoded into the UTF-8 byte
 939 sequence representing U+FFFD (REPLACEMENT CHARACTER)."
 940
 941  '(ccl-decode-mule-utf-8 . ccl-encode-mule-utf-8)
 942  `((safe-charsets
 943     ascii
 944     eight-bit-control
 945     eight-bit-graphic
 946     latin-iso8859-1
 947     mule-unicode-0100-24ff
 948     mule-unicode-2500-33ff
 949     mule-unicode-e000-ffff
 950     ,@(if utf-translate-cjk-mode
 951           utf-translate-cjk-charsets))
 952    (mime-charset . utf-8)
 953    (coding-category . coding-category-utf-8)
 954    (valid-codes (0 . 255))
 955    (pre-write-conversion . utf-8-pre-write-conversion)
 956    (post-read-conversion . utf-8-post-read-conversion)
 957    (translation-table-for-encode . utf-translation-table-for-encode)
 958    (dependency unify-8859-on-encoding-mode
 959                unify-8859-on-decoding-mode
 960                utf-fragment-on-decoding
 961                utf-translate-cjk-mode)))
 962
 963 (define-coding-system-alias 'utf-8 'mule-utf-8)
 964
 965 ;; I think this needs special private charsets defined for the
 966 ;; untranslated sequences, if it's going to work well.
 967
 968 ;;; (defun utf-8-compose-function (pos to pattern &optional string)
 969 ;;;   (let* ((prop (get-char-property pos 'composition string))
 970 ;;;      (l (and prop (- (cadr prop) (car prop)))))
 971 ;;;     (cond ((and l (> l (- to pos)))
 972 ;;;        (delete-region pos to))
 973 ;;;       ((and (> (char-after pos) 224)
 974 ;;;             (< (char-after pos) 256)
 975 ;;;             (save-restriction
 976 ;;;               (narrow-to-region pos to)
 977 ;;;               (utf-8-compose)))
 978 ;;;        t))))
 979
 980 ;;; (dotimes (i 96)
 981 ;;;   (aset composition-function-table
 982 ;;;     (+ 128 i)
 983 ;;;     `((,(string-as-multibyte "[\200-\237\240-\377]")
 984 ;;;        . utf-8-compose-function))))
 985
 986 ;;; arch-tag: b08735b7-753b-4ae6-b754-0f3efe4515c5
 987 ;;; utf-8.el ends here