Re: [PATCH] xml-escape-region

[Daniel Colascione]

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On Oct 8, 2009, at 1:29 AM, Stefan Monnier wrote:

> > > > +;;;##autoload
> > > > +(defun xml-escape-region (beg end)
> > > > +  (interactive "*r")
> > > > +  (let ((escaped (xml-escape-string (buffer-substring beg end))))
> > > > +    (delete-region beg end)
> > > > +    (insert escaped)))
> > >
> > > I'd rather not autoload such a function.
>
> > Do you mean that it should be loaded all the time, or that the user  
> > should
> > have to explicitly load xml.el before using the function?
>
> Yes.
>
> > If the latter, then that would make binding it to a key
> > less convenient.
>
> Hmm... didn't notice you defined it as a command.  How often/when do  
> you
> need to use/bind such a command other than in an sgml/xml-related file
> (where the major mode might decide to preload such a command)?

Pretty often, actually. XML (or XML-like syntax) crops up in a lot of  
places, including
literal strings in many programming languages. Some basic XML-editing  
functionality being available everywhere would be useful.
> >  (let ((search-re (mapconcat #'regexp-quote
> >                              (mapcar #'cdr xml-entity-alist)
> >                              "\\|"))
>
> Rather than a big \| of single chars, why not make a [...] regexp?
> If you use regexp-opt, it should happen automatically.

I figured the constant-factor overhead of regexp-opt (and its  
autoloading) wasn't worth it for such a simple regexp.


> Actually, now that I look at it, xml-entity-alist is poorly defined.
> Instead of being a list of pairs of string and string (where the  
> second
> string is always of size 1), it should be a list of pairs of string
> and char.

I think the idea was to be able to replace multi-character strings  
with XML entities defined for the current document.

> Also this code is also applicable to sgml and there's related
> code in sgml-mode.el.  If someone wants to consolidate, that would
> be welcome.

Does anyone actually use the unquotep parameter? It seems like quoting  
and unquoting should be separate functions. Nevertheless, the patch  
below should preserve existing behavior. I've also renamed the XML  
functions to better match existing code, e.g., base64.

> >    (save-excursion
> >      (goto-char beg)
> >      (while (re-search-forward search-re end t)
> >        (replace-match (concat "&"
> >                               (car (rassoc (match-string 0)
> >                                            xml-entity-alist))
> >                               ";"))))))
>
> If you use a backward-search, you don't need to turn `end' (nor  
> `start')
> into a marker.

Good idea.

Index: xml.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/xml.el,v
retrieving revision 1.64
diff -u -r1.64 xml.el
- --- xml.el    5 Jan 2009 03:19:57 -0000       1.64
+++ xml.el      8 Oct 2009 05:58:20 -0000
@@ -840,6 +840,40 @@

 (defalias 'xml-print 'xml-debug-print)

+
+;;;###autoload
+(defun xml-encode-region (start end)
+  "XML-escape text between START and END according to `xml-entity- 
alist`."
+  (interactive "*r")
+
+  (let ((search-re (mapconcat #'regexp-quote
+                              (mapcar #'cdr xml-entity-alist)
+                              "\\|")))
+    (save-excursion
+      (goto-char end)
+      (while (re-search-backward search-re start t)
+        (replace-match (concat "&"
+                               (car (rassoc (match-string 0)
+                                            xml-entity-alist))
+                               ";"))
+        (goto-char (match-beginning 0))))))
+
+;;;###autoload
+(defun xml-decode-region (start end)
+  "Decode XML entities between START and END according to `xml-entity- 
alist`."
+  (interactive "*r")
+  (let ((search-re (concat "&\\("
+                           (mapconcat #'regexp-quote
+                                      (mapcar #'car xml-entity-alist)
+                                      "\\|")
+                           "\\);")))
+
+    (save-excursion
+      (goto-char end)
+      (while (re-search-backward search-re start t)
+        (replace-match (cdr (assoc (match-string 1) xml-entity-alist)))
+        (goto-char (match-beginning 0))))))
+
 (defun xml-escape-string (string)
   "Return the string with entity substitutions made from
 xml-entity-alist."
Index: textmodes/sgml-mode.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/textmodes/sgml-mode.el,v
retrieving revision 1.141
diff -u -r1.141 sgml-mode.el
- --- textmodes/sgml-mode.el    24 Sep 2009 23:22:20 -0000      1.141
+++ textmodes/sgml-mode.el      8 Oct 2009 05:58:21 -0000
@@ -1097,21 +1097,10 @@
 Only &, < and > are quoted, the rest is left untouched.
 With prefix argument UNQUOTEP, unquote the region."
   (interactive "r\nP")
- -  (save-restriction
- -    (narrow-to-region start end)
- -    (goto-char (point-min))
- -    (if unquotep
- -     ;; FIXME: We should unquote other named character references as well.
- -     (while (re-search-forward
- -             "\\(&\\(amp\\|\\(l\\|\\(g\\)\\)t\\)\\)[][<>&;\n\t \"%!'(),/=?]"
- -             nil t)
- -       (replace-match (if (match-end 4) ">" (if (match-end 3) "<" "&")) t t
- -                      nil (if (eq (char-before (match-end 0)) ?\;) 0 1)))
- -      (while (re-search-forward "[&<>]" nil t)
- -     (replace-match (cdr (assq (char-before) '((?& . "&amp;")
- -                                               (?< . "&lt;")
- -                                               (?> . "&gt;"))))
- -                    t t)))))
+  (if unquote
+      (xml-decode-region start end)
+    (xml-encode-region start end)))
+

 (defun sgml-pretty-print (beg end)
   "Simple-minded pretty printer for SGML.

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