-;;; utf-8.el --- limited UTF-8 decoding/encoding support
+;;; utf-8.el --- limited UTF-8 decoding/encoding support -*- coding: iso-2022-7bit-*-
;; Copyright (C) 2001 Electrotechnical Laboratory, JAPAN.
;; Licensed to the Free Software Foundation.
;;; Commentary:
-;; The coding-system `mule-utf-8' supports encoding/decoding of the
-;; following character sets to and from UTF-8:
+;; The coding-system `mule-utf-8' basically supports encoding/decoding
+;; of the following character sets to and from UTF-8:
;;
;; ascii
;; eight-bit-control
;; mule-unicode-2500-33ff
;; mule-unicode-e000-ffff
;;
-;; Characters of other character sets cannot be encoded with
-;; mule-utf-8. Note that the mule-unicode charsets currently lack
-;; case and syntax information, so things like `downcase' will only
-;; work for characters from ASCII and Latin-1.
-;;
;; On decoding, Unicode characters that do not fit into the above
;; character sets are handled as `eight-bit-control' or
;; `eight-bit-graphic' characters to retain the information about the
;; original byte sequence.
+;;
+;; Characters from other character sets can be encoded with
+;; mule-utf-8 by populating the table `ucs-mule-to-mule-unicode' and
+;; registering the translation with `register-char-codings'.
;; UTF-8 is defined in RFC 2279. A sketch of the encoding is:
;;; Code:
+(defvar ucs-mule-to-mule-unicode (make-translation-table)
+ "Translation table for encoding to `mule-utf-8'.")
+;; Could have been done by ucs-tables loaded before.
+(unless (get 'ucs-mule-to-mule-unicode 'translation-table)
+ (define-translation-table 'ucs-mule-to-mule-unicode ucs-mule-to-mule-unicode))
(define-ccl-program ccl-decode-mule-utf-8
;;
;; charset | bytes in utf-8 | bytes in emacs
;; ascii | 1 | 1
;; -----------------------+----------------+---------------
;; eight-bit-control | 2 | 2
+ ;; eight-bit-graphic | 2 | 1
;; latin-iso8859-1 | 2 | 2
;; -----------------------+----------------+---------------
;; mule-unicode-0100-24ff | 2 | 4
(loop
(if (r5 < 0)
((r1 = -1)
- (read-multibyte-character r0 r1))
+ (read-multibyte-character r0 r1)
+ (translate-character ucs-mule-to-mule-unicode r0 r1))
(;; We have already done read-multibyte-character.
(r0 = r5)
(r1 = r6)
eight-bit-graphic, latin-iso8859-1 and mule-unicode-* are recognized.
Others are encoded as U+FFFD.")
+;; Dummy definition so that the CCL can be checked correctly; the
+;; actual data are loaded on demand.
+(unless (boundp 'ucs-mule-8859-to-mule-unicode) ; don't zap it
+ (define-translation-table 'ucs-mule-8859-to-mule-unicode))
+
+(defsubst utf-8-untranslated-to-ucs ()
+ (let ((b1 (char-after))
+ (b2 (char-after (1+ (point))))
+ (b3 (char-after (+ 2 (point))))
+ (b4 (char-after (+ 4 (point)))))
+ (if (and b1 b2 b3)
+ (cond ((< b1 ?\xf0)
+ (setq b2 (lsh (logand b2 ?\x3f) 6))
+ (setq b3 (logand b3 ?\x3f))
+ (logior b3 (logior b2 (lsh (logand b1 ?\x0f) 12))))
+ (b4
+ (setq b2 (lsh (logand b2 ?\x3f) 12))
+ (setq b3 (lsh (logand b3 ?\x3f) 6))
+ (setq b4 (logand b4 ?\x3f))
+ (logior b4 (logior b3 (logior b2 (lsh (logand b1 ?\x07)
+ 18)))))))))
+
+(defun utf-8-help-echo (window object position)
+ (format "Untranslated Unicode U+%04X"
+ (get-char-property position 'untranslated-utf-8 object)))
+
+(defvar utf-8-subst-table nil
+ "If non-nil, a hash table mapping `untranslatable utf-8' to Emacs characters.")
+
+;; We compose the untranslatable sequences into a single character.
+;; This is infelicitous for editing, because there's currently no
+;; mechanism for treating compositions as atomic, but is OK for
+;; display. We try to compose an appropriate character from a hash
+;; table of CJK characters to display correctly. Otherwise we use
+;; U+FFFD. What we really should have is hash table lookup from CCL
+;; so that we could do this properly. This function GCs too much.
+(defsubst utf-8-compose ()
+ "Put a suitable composition on an untranslatable sequence.
+Return the sequence's length."
+ (let* ((u (utf-8-untranslated-to-ucs))
+ (l (and u (if (>= u ?\x10000)
+ 4
+ 3)))
+ (subst (and utf-8-subst-table (gethash u utf-8-subst-table))))
+ (when u
+ (put-text-property (point) (min (point-max) (+ l (point)))
+ 'untranslated-utf-8 u)
+ (unless subst
+ (put-text-property (point) (min (point-max) (+ l (point)))
+ 'help-echo 'utf-8-help-echo)
+ (setq subst ?\e$,3u=\e(B))
+ (compose-region (point) (+ l (point)) subst)
+ l)))
+
+(defcustom utf-8-compose-scripts nil
+ "*Non-nil means compose various scipts on decoding utf-8 text."
+ :group 'mule
+ :type 'boolean) ; omitted in Emacs 21.1
+
+(defun utf-8-post-read-conversion (length)
+ "Compose untranslated utf-8 sequences into single characters.
+Also compose particular scripts if `utf-8-compose-scripts' is non-nil."
+ (save-excursion
+ ;; Can't do eval-when-compile to insert a multibyte constant
+ ;; version of the string in the loop, since it's always loaded as
+ ;; unibyte from a byte-compiled file.
+ (let ((range (string-as-multibyte "^\341-\377")))
+ (while (and (skip-chars-forward
+ range)
+ (not (eobp)))
+ (forward-char (utf-8-compose)))))
+ ;; Fixme: Takahashi-san implies it may not work this easily -- needs
+ ;; checking with him.
+ (when (and utf-8-compose-scripts (> length 1))
+ ;; These currently have definitions which cover the relevant
+ ;; Unicodes. We could avoid loading thai-util &c by checking
+ ;; whether the region contains any characters with the appropriate
+ ;; categories. There aren't yet Unicode-based rules for Tibetan.
+ (save-excursion (setq length (diacritic-post-read-conversion length)))
+ (save-excursion (setq length (thai-post-read-conversion length)))
+ (save-excursion (setq length (lao-post-read-conversion length)))
+ (save-excursion (setq length (devanagari-post-read-conversion length))))
+ length)
+
+(defun utf-8-pre-write-conversion (beg end)
+ "Semi-dummy pre-write function effectively to autoload ucs-tables."
+ ;; Ensure translation table is loaded.
+ (require 'ucs-tables)
+ ;; Don't do this again.
+ (coding-system-put 'mule-utf-8 'pre-write-conversion nil)
+ nil)
+
(make-coding-system
'mule-utf-8 4 ?u
"UTF-8 encoding for Emacs-supported Unicode characters.
-The supported Emacs character sets are:
- ascii
- eight-bit-control
- eight-bit-graphic
- latin-iso8859-1
- mule-unicode-0100-24ff
- mule-unicode-2500-33ff
- mule-unicode-e000-ffff
+The supported Emacs character sets are the following, plus others
+which may be included in the translation table
+`ucs-mule-to-mule-unicode':
+ ascii
+ eight-bit-control
+ eight-bit-graphic
+ latin-iso8859-1
+ latin-iso8859-2
+ latin-iso8859-3
+ latin-iso8859-4
+ cyrillic-iso8859-5
+ greek-iso8859-7
+ hebrew-iso8859-8
+ latin-iso8859-9
+ latin-iso8859-14
+ latin-iso8859-15
+ mule-unicode-0100-24ff
+ mule-unicode-2500-33ff
+ mule-unicode-e000-ffff
Unicode characters out of the ranges U+0000-U+33FF and U+E200-U+FFFF
are decoded into sequences of eight-bit-control and eight-bit-graphic
-characters to preserve their byte sequences. Emacs characters out of
-these ranges are encoded into U+FFFD.
-
-Note that, currently, characters in the mule-unicode charsets have no
-syntax and case information. Thus, for instance, upper- and
-lower-casing commands won't work with them."
+characters to preserve their byte sequences and composed to display as
+a single character. Emacs characters that can't be encoded to these
+ranges are encoded as U+FFFD."
'(ccl-decode-mule-utf-8 . ccl-encode-mule-utf-8)
'((safe-charsets
eight-bit-control
eight-bit-graphic
latin-iso8859-1
+ latin-iso8859-15
+ latin-iso8859-14
+ latin-iso8859-9
+ hebrew-iso8859-8
+ greek-iso8859-7
+ cyrillic-iso8859-5
+ latin-iso8859-4
+ latin-iso8859-3
+ latin-iso8859-2
+ vietnamese-viscii-lower
+ vietnamese-viscii-upper
+ thai-tis620
+ ipa
+ ethiopic
+ indian-is13194
+ katakana-jisx0201
+ chinese-sisheng
+ lao
mule-unicode-0100-24ff
mule-unicode-2500-33ff
mule-unicode-e000-ffff)
(mime-charset . utf-8)
(coding-category . coding-category-utf-8)
- (valid-codes (0 . 255))))
+ (valid-codes (0 . 255))
+ (pre-write-conversion . utf-8-pre-write-conversion)
+ (post-read-conversion . utf-8-post-read-conversion)))
(define-coding-system-alias 'utf-8 'mule-utf-8)
+;; I think this needs special private charsets defined for the
+;; untranslated sequences, if it's going to work well.
+
+;;; (defun utf-8-compose-function (pos to pattern &optional string)
+;;; (let* ((prop (get-char-property pos 'composition string))
+;;; (l (and prop (- (cadr prop) (car prop)))))
+;;; (cond ((and l (> l (- to pos)))
+;;; (delete-region pos to))
+;;; ((and (> (char-after pos) 224)
+;;; (< (char-after pos) 256)
+;;; (save-restriction
+;;; (narrow-to-region pos to)
+;;; (utf-8-compose)))
+;;; t))))
+
+;;; (dotimes (i 96)
+;;; (aset composition-function-table
+;;; (+ 128 i)
+;;; `((,(string-as-multibyte "[\200-\237\240-\377]")
+;;; . utf-8-compose-function))))
+
;;; utf-8.el ends here
projects / emacs.git / commitdiff