SAX: Next Round (Lexical Event Handler)

David Megginson david at
Sun Jan 31 21:30:56 GMT 1999

David Brownell writes:

 > > > I haven't checked, but I think that this gives us everything we need
 > > > for DOM level one.
 > Doesn't quite ... there's some more DTD information needed to:
 > 	*  ensure that PIs within the DTD (e.g. internal subset)
 > 	   don't show up anywhere in the DOM tree (ugh);

You can determine this using the start/end DTD events and start/end
entity events, I think.

 > 	*  see declarations of external general entities;

Do we need the declarations, or just the boundaries -- or, in other
words, do we need to provide information about declared but unused
external parsed entities?  Sorry I'm too lazy to puzzle this out from
the spec right now.

 > 	*  expose values of defaults so that the DOM can ensure
 > 	   that defaulted attributes always have values;

The parser should take care of this.

 > 	*  distinguish attributes which were defaulted from those
 > 	   that were explicitly in the document.

Yes, this is necessary, as a few others have also pointed out
(grumble, grumble).

 > (In addition the above, if XML namespaces are to be layerable over
 > a normal XML 1.0 parser, declarations of all other entities need to
 > be exposed so they can be examined for conformance:  they must not
 > contain colons!)

This is probably overkill for SAX -- if someone wants to layer
namespaces on top of SAX, they'll have to miss this one.

 > > I wonder whether LexicalHandler ought to extend DocumentHandler.  The
 > > events it reports are synchronous with the events reported by
 > > DocumentHandler.  It seems to me that applications are always going to
 > > want to implement either DocumentHandler or both DocumentHandler and
 > > LexicalHandler.

Probably -- the problem is that if we extend Parser then we'll have
both a setDocumentHandler and a setLexicalDocumentHandler event, and
that causes some funny problems that I'd rather punt.

All the best,


David Megginson                 david at

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