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Diffstat (limited to 'lisp/nxml/nxml-enc.el')
| -rw-r--r-- | lisp/nxml/nxml-enc.el | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/lisp/nxml/nxml-enc.el b/lisp/nxml/nxml-enc.el new file mode 100644 index 00000000000..115db17ad70 --- /dev/null +++ b/lisp/nxml/nxml-enc.el @@ -0,0 +1,173 @@ +;;; nxml-enc.el --- XML encoding auto-detection + +;; Copyright (C) 2003, 2007 Free Software Foundation, Inc. + +;; Author: James Clark +;; Keywords: XML + +;; 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 3, 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, Inc., 51 Franklin Street, Fifth Floor, +;; Boston, MA 02110-1301, USA. + +;;; Commentary: + +;; User entry points are nxml-start-auto-coding and +;; nxml-stop-auto-coding. This is separate from nxml-mode, because +;; this cannot be autoloaded. It may use +;; `xmltok-get-declared-encoding-position' which can be autoloaded. +;; It's separate from rng-auto.el so it can be byte-compiled, and +;; because it provides independent, useful functionality. + +;;; Code: + +(defvar nxml-file-name-ignore-case + (memq system-type '(vax-vms windows-nt))) + +(defvar nxml-cached-file-name-auto-coding-regexp nil) +(defvar nxml-cached-auto-mode-alist nil) + +(defun nxml-file-name-auto-coding-regexp () + "Return regexp for filenames for which XML auto-coding should be done." + (if (eq auto-mode-alist nxml-cached-auto-mode-alist) + nxml-cached-file-name-auto-coding-regexp + (let ((alist auto-mode-alist) + (case-fold-search nxml-file-name-ignore-case) + regexps) + (setq nxml-cached-auto-mode-alist alist) + (while alist + (when (eq (cdar alist) 'nxml-mode) + (setq regexps (cons (caar alist) regexps))) + (setq alist (cdr alist))) + (setq nxml-cached-file-name-auto-coding-regexp + (if (null (cdr regexps)) + (car regexps) + (mapconcat (lambda (r) + (concat "\\(?:" r "\\)")) + regexps + "\\|")))))) + +(defvar nxml-non-xml-set-auto-coding-function nil + "The function that `set-auto-coding-function' should call for non-XML files.") +(defun nxml-set-auto-coding (file-name size) + (if (let ((case-fold-search nxml-file-name-ignore-case) + (regexp (nxml-file-name-auto-coding-regexp))) + (and regexp + (string-match regexp file-name))) + (nxml-set-xml-coding file-name size) + (and nxml-non-xml-set-auto-coding-function + (funcall nxml-non-xml-set-auto-coding-function file-name size)))) + +(defun nxml-set-xml-coding (file-name size) + "Function to use as `set-auto-coding-function' when file is known to be XML." + (nxml-detect-coding-system (+ (point) (min size 1024)))) + +(declare-function xmltok-get-declared-encoding-position "xmltok" + (&optional limit)) ; autoloaded + +(defun nxml-detect-coding-system (limit) + (if (< limit (+ (point) 2)) + (if (eq (char-after) 0) 'no-conversion 'utf-8) + (let ((first-two-chars (list (char-after) + (char-after (1+ (point)))))) + (cond ((equal first-two-chars '(#xFE #xFF)) + (and (coding-system-p 'utf-16-be) 'utf-16-be)) + ((equal first-two-chars '(#xFF #xFE)) + (and (coding-system-p 'utf-16-le) 'utf-16-le)) + ((memq 0 first-two-chars) + ;; Certainly not well-formed XML; + ;; perhaps UTF-16 without BOM. + ;; In any case, we can't handle it. + ;; no-conversion gives the user a chance to fix it. + 'no-conversion) + ;; There are other things we might try here in the future + ;; eg UTF-8 BOM, UTF-16 with no BOM + ;; translate to EBCDIC + (t + (let ((enc-pos (xmltok-get-declared-encoding-position limit))) + (cond ((consp enc-pos) + (or (nxml-mime-charset-coding-system + (buffer-substring-no-properties (car enc-pos) + (cdr enc-pos))) + ;; We have an encoding whose name we don't recognize. + ;; What to do? + ;; raw-text seems the best bet: since we got + ;; the XML decl it must be a superset of ASCII, + ;; so we don't need to go to no-conversion + 'raw-text)) + (enc-pos 'utf-8) + ;; invalid XML declaration + (t nil)))))))) + +(defun nxml-mime-charset-coding-system (charset) + (let ((charset-sym (intern (downcase charset))) + (coding-systems (coding-system-list t)) + coding-system ret) + (while (and coding-systems (not ret)) + (setq coding-system (car coding-systems)) + (if (eq (coding-system-get coding-system 'mime-charset) + charset-sym) + (setq ret coding-system) + (setq coding-systems (cdr coding-systems)))) + ret)) + +(defun nxml-start-auto-coding () + "Do encoding auto-detection as specified in the XML standard. +Applied to any files that `auto-mode-alist' says should be handled by +`nxml-mode'." + (interactive) + (unless (eq set-auto-coding-function 'nxml-set-auto-coding) + (let ((inhibit-quit t)) + (setq nxml-non-xml-set-auto-coding-function set-auto-coding-function) + (setq set-auto-coding-function 'nxml-set-auto-coding)))) + +(defun nxml-stop-auto-coding () + "Stop doing encoding auto-detection as specified in the XML standard." + (interactive) + (when (eq set-auto-coding-function 'nxml-set-auto-coding) + (let ((inhibit-quit t)) + (setq set-auto-coding-function nxml-non-xml-set-auto-coding-function) + (setq nxml-non-xml-set-auto-coding-function nil)))) + +(unless (coding-system-p 'us-ascii) + (make-coding-system + ;; Unicode Emacs uses ?- last time I looked + 'us-ascii 2 ?- + "ISO 2022 based 7-bit encoding for ASCII (MIME:US-ASCII)" + '(ascii) + '((safe-charsets ascii) + (mime-charset . us-ascii)))) + +;; Emacs 21.3.50 makes us-ascii an alias for iso-safe without +;; giving it a mime-charset property. +(unless (coding-system-get 'us-ascii 'mime-charset) + (coding-system-put 'us-ascii 'mime-charset 'us-ascii)) + +;; Work around bug in Emacs 21.3 + +(when (and (coding-system-p 'utf-16-le) + (eq (coding-system-get 'utf-16-le 'pre-write-conversion) + 'utf-16-le-pre-write-conversion)) + (coding-system-put 'utf-16-le 'pre-write-conversion nil)) + +(when (and (coding-system-p 'utf-16-le) + (eq (coding-system-get 'utf-16-be 'pre-write-conversion) + 'utf-16-be-pre-write-conversion)) + (coding-system-put 'utf-16-be 'pre-write-conversion nil)) + +(provide 'nxml-enc) + +;; arch-tag: c2436247-78f3-418c-8069-85dc5335d083 +;;; nxml-enc.el ends here |