1 ;;; nxml-enc.el --- XML encoding auto-detection
3 ;; Copyright (C) 2003, 2007, 2008 Free Software Foundation, Inc.
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software; you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation; either version 3, or (at your option)
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs; see the file COPYING. If not, write to the
22 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
23 ;; Boston, MA 02110-1301, USA.
27 ;; User entry points are nxml-start-auto-coding and
28 ;; nxml-stop-auto-coding. This is separate from nxml-mode, because
29 ;; this cannot be autoloaded. It may use
30 ;; `xmltok-get-declared-encoding-position' which can be autoloaded.
31 ;; It's separate from rng-auto.el so it can be byte-compiled, and
32 ;; because it provides independent, useful functionality.
36 (defvar nxml-file-name-ignore-case
37 (memq system-type
'(vax-vms windows-nt
)))
39 (defvar nxml-cached-file-name-auto-coding-regexp nil
)
40 (defvar nxml-cached-auto-mode-alist nil
)
42 (defun nxml-file-name-auto-coding-regexp ()
43 "Return regexp for filenames for which XML auto-coding should be done."
44 (if (eq auto-mode-alist nxml-cached-auto-mode-alist
)
45 nxml-cached-file-name-auto-coding-regexp
46 (let ((alist auto-mode-alist
)
47 (case-fold-search nxml-file-name-ignore-case
)
49 (setq nxml-cached-auto-mode-alist alist
)
51 (when (eq (cdar alist
) 'nxml-mode
)
52 (setq regexps
(cons (caar alist
) regexps
)))
53 (setq alist
(cdr alist
)))
54 (setq nxml-cached-file-name-auto-coding-regexp
55 (if (null (cdr regexps
))
57 (mapconcat (lambda (r)
58 (concat "\\(?:" r
"\\)"))
62 (defvar nxml-non-xml-set-auto-coding-function nil
63 "The function that `set-auto-coding-function' should call for non-XML files.")
64 (defun nxml-set-auto-coding (file-name size
)
65 (if (let ((case-fold-search nxml-file-name-ignore-case
)
66 (regexp (nxml-file-name-auto-coding-regexp)))
68 (string-match regexp file-name
)))
69 (nxml-set-xml-coding file-name size
)
70 (and nxml-non-xml-set-auto-coding-function
71 (funcall nxml-non-xml-set-auto-coding-function file-name size
))))
73 (defun nxml-set-xml-coding (file-name size
)
74 "Function to use as `set-auto-coding-function' when file is known to be XML."
75 (nxml-detect-coding-system (+ (point) (min size
1024))))
77 (declare-function xmltok-get-declared-encoding-position
"xmltok"
78 (&optional limit
)) ; autoloaded
80 (defun nxml-detect-coding-system (limit)
81 (if (< limit
(+ (point) 2))
82 (if (eq (char-after) 0) 'no-conversion
'utf-8
)
83 (let ((first-two-chars (list (char-after)
84 (char-after (1+ (point))))))
85 (cond ((equal first-two-chars
'(#xFE
#xFF
))
86 (and (coding-system-p 'utf-16-be
) 'utf-16-be
))
87 ((equal first-two-chars
'(#xFF
#xFE
))
88 (and (coding-system-p 'utf-16-le
) 'utf-16-le
))
89 ((memq 0 first-two-chars
)
90 ;; Certainly not well-formed XML;
91 ;; perhaps UTF-16 without BOM.
92 ;; In any case, we can't handle it.
93 ;; no-conversion gives the user a chance to fix it.
95 ;; There are other things we might try here in the future
96 ;; eg UTF-8 BOM, UTF-16 with no BOM
97 ;; translate to EBCDIC
99 (let ((enc-pos (xmltok-get-declared-encoding-position limit
)))
100 (cond ((consp enc-pos
)
101 (or (nxml-mime-charset-coding-system
102 (buffer-substring-no-properties (car enc-pos
)
104 ;; We have an encoding whose name we don't recognize.
106 ;; raw-text seems the best bet: since we got
107 ;; the XML decl it must be a superset of ASCII,
108 ;; so we don't need to go to no-conversion
111 ;; invalid XML declaration
114 (defun nxml-mime-charset-coding-system (charset)
115 (let ((charset-sym (intern (downcase charset
)))
116 (coding-systems (coding-system-list t
))
118 (while (and coding-systems
(not ret
))
119 (setq coding-system
(car coding-systems
))
120 (if (eq (coding-system-get coding-system
'mime-charset
)
122 (setq ret coding-system
)
123 (setq coding-systems
(cdr coding-systems
))))
126 (defun nxml-start-auto-coding ()
127 "Do encoding auto-detection as specified in the XML standard.
128 Applied to any files that `auto-mode-alist' says should be handled by
131 (unless (eq set-auto-coding-function
'nxml-set-auto-coding
)
132 (let ((inhibit-quit t
))
133 (setq nxml-non-xml-set-auto-coding-function set-auto-coding-function
)
134 (setq set-auto-coding-function
'nxml-set-auto-coding
))))
136 (defun nxml-stop-auto-coding ()
137 "Stop doing encoding auto-detection as specified in the XML standard."
139 (when (eq set-auto-coding-function
'nxml-set-auto-coding
)
140 (let ((inhibit-quit t
))
141 (setq set-auto-coding-function nxml-non-xml-set-auto-coding-function
)
142 (setq nxml-non-xml-set-auto-coding-function nil
))))
144 (unless (coding-system-p 'us-ascii
)
146 ;; Unicode Emacs uses ?- last time I looked
148 "ISO 2022 based 7-bit encoding for ASCII (MIME:US-ASCII)"
150 '((safe-charsets ascii
)
151 (mime-charset . us-ascii
))))
153 ;; Emacs 21.3.50 makes us-ascii an alias for iso-safe without
154 ;; giving it a mime-charset property.
155 (unless (coding-system-get 'us-ascii
'mime-charset
)
156 (coding-system-put 'us-ascii
'mime-charset
'us-ascii
))
158 ;; Work around bug in Emacs 21.3
160 (when (and (coding-system-p 'utf-16-le
)
161 (eq (coding-system-get 'utf-16-le
'pre-write-conversion
)
162 'utf-16-le-pre-write-conversion
))
163 (coding-system-put 'utf-16-le
'pre-write-conversion nil
))
165 (when (and (coding-system-p 'utf-16-le
)
166 (eq (coding-system-get 'utf-16-be
'pre-write-conversion
)
167 'utf-16-be-pre-write-conversion
))
168 (coding-system-put 'utf-16-be
'pre-write-conversion nil
))
172 ;; arch-tag: c2436247-78f3-418c-8069-85dc5335d083
173 ;;; nxml-enc.el ends here