[Emacs-diffs] Changes to lisp/nxml/nxml-enc.el

[Mark A. Hershberger]

CVSROOT:        /sources/emacs
Module name:    emacs
Changes by:     Mark A. Hershberger <hexmode>   07/11/23 06:58:00

Index: lisp/nxml/nxml-enc.el
===================================================================
RCS file: lisp/nxml/nxml-enc.el
diff -N lisp/nxml/nxml-enc.el
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ lisp/nxml/nxml-enc.el       23 Nov 2007 06:57:49 -0000      1.1
@@ -0,0 +1,167 @@
+;;; nxml-enc.el --- XML encoding auto-detection
+
+;; Copyright (C) 2003 Free Software Foundation, Inc.
+
+;; Author: James Clark
+;; Keywords: XML
+
+;; This program 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 of
+;; the License, or (at your option) any later version.
+
+;; This program 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 this program; if not, write to the Free
+;; Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+;; MA 02111-1307 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))))
+
+(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)
+
+;;; nxml-enc.el ends here