[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: SAX2/Java: Towards a final form
* Stefan Haustein | | Is "no namespace" reported with a null or empty String (for interned | Strings, the equals problem does not exist)? * David Megginson | | Empty string sounds like a reasonable suggestion when Namespace | processing is being performed; null when it is not (so that a bugs | in code will show up sooner). There is a problem with this: SAX filters should be able to compare names without knowing whether namespace processing is on or not. Allowing parts of names to be null makes this much more complicated, since this is a comparison of two three-string tuples. So from a filter point of view it would be much better if no part of a name could ever be null. (I'm a bit unsure what to do with the raw name when there is no original raw name.) | That's a good question -- should SAX2 require that all names and | Namespace URIs be interned (i.e. == to the results of | java.lang.String.intern)? This sounds like it could cause a huge performance gap between implementations. I think the MSXML driver and the SAX1 adapter will have to intern every name-part string that is passed to them, which I assume would be very costly. (The alternative would be breaking applications, unless there is a cheaper way.) Also, many parsers already do their own interning and support for SAX2, and these would then require either the solution above or a (non-costly) change to the parser itself. This definitely sounds like something that is easily forgotten, thus causing incompatibilities. Perhaps we should instead add an optional read-only property that returns an implementation of a StringInterner interface, which could look something like: public interface StringInterner { public String intern(String aString); public void clear(); // empties all internal tables, but is not // guaranteed to have an effect } Support for this property would then imply that all reported name-part strings are interned. We could also add a default implementation that just does aString.intern(), to make life easier for the implementors. --Lars M. xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ and on CD-ROM/ISBN 981-02-3594-1 To unsubscribe, mailto:majordomo@i... the following message; unsubscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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