Re: Problems with DOM Parsing/Serialization and character encodings?

On 26 May 2004 04:41:00 -0700, matthew@xxxxxxxxxxxxxxxxxxxx (Matthew
Wilson) wrote:

>Are there any issues using Mozilla DOM Parsing or Serialization and
>character encodings?
>
>For example, using Cyrillic characters via numeric entity references
>(I hope I have that term correct) in an ISO-8859-1 document:
>
>   var text = "Выбрать";
>   var xml = "<?xml version='1.0' encoding='ISO-8859-1'?>\n<test>" +
>text + "</test>";
>   window.alert (xml);
>
>This outputs the string exactly as you would expect, with the numeric
>characters intact.
>
>If I then make an XMLDocument out of the text, and print the value of
>the text node:
>
>   var originalDoc = new DOMParser().parseFromString(xml, "text/xml");
>   window.alert (originalDoc.documentElement.childNodes[0].data);
>
>then I see the actual Cyrillic characters. I'll paste them in here,
>but I don't know how successful that will be:
>&#1042;&#1099;&#1073;&#1088;&#1072;&#1090;&#1100;

Alright, that should have appeared as a string of Cyrcill characters.

>I think that's still correct.
>
>Then if I serialize it back to a string and print the result, the
>numeric character entity references are gone, I still have the
>Cyrillic characters, and the XML declaration still has an encoding of
>ISO-8859-1:
>
>   var serializedDoc = new XMLSerializer().serializeToString
>(originalDoc);
>   window.alert (serializedDoc);
>
><?xml version="1.0" encoding="ISO-8859-1"?>
><test>&#1042;&#1099;&#1073;&#1088;&#1072;&#1090;&#1100;</test>
>
>That looks wrong to me. Any opinions?

OK, answering my own question: serializeToString only promises to
return the serialization "in the form of a Unicode string", that is,
it doesn't mind if it includes illegal characters (according to the
declared character encoding).

And I should use serializeToStream with the specified encoding if I
want to make sure that any improper characters are suitably escaped.

Is that the intention?

If so, what's the easiest way of getting a scriptable output stream
which I can use for serializeToStream? I just want to store the output
in memory.

At the moment I have the following ugly hack:
    var str = Components.classes["@mozilla.org/supports-string;1"].

createInstance(Components.interfaces.nsISupportsString);
    var outputStream = {
        write: function(buf, count) {
           str.data = str.data + buf;
           return count;
       }
    };
    serializer.serializeToStream (transformedDocument, outputStream,
"UTF-8");

but I would rather have a real nsIOutputStream implementation.

-- 
Matthew