On Mon, Jan 14, 2002 at 06:24:29PM -0500, Barrie Slaymaker wrote:
>  At Matt's suggestion, there's a new machine that allows record oriented
>  processing of XML, XML::SAX::ByRecord, along with a supporting SAX
>  filter XML::Filter::DocSplitter.  X::S::ByRecord is documented below,
>  feedback/testing/patches on any/all of this is quite welcome.

I've been casually glancing at the list recently, and a couple of
mentions of XML::RAX started me thinking.

Is there a standard idiom for converting a SAX machine into an
iterator?  That is, something like this:

	my $xmlp = new XML::SAXIterator();

	## set iterator options
	## connect to a driver that produces SAX events
	## use $xmlp to drive the entire process

	while (defined ($result = $xmlp-> next())) {
		## process the result object
		## could be a tree fragment, a la DOM or XML::Twig
		## could be some other type of data entirely
	}

Writing event-based parsing code for lo these many years, my gut
feeling is that this isn't possible with XML::Parser or the SAX model
as it stands today.

However, it would be with the addition of a pause() method and a
next() method.  The pause() method would be called within a handler
stack, and tell the parser to pause it's dispatch loop; at the end
of the current handler, it would exit from the dispatch loop,
returning control to the main program.  The next() method would
start parsing if it hasn't begun yet, and would continue parsing
from where the parser left off previously.

A SAX parser would need to implement these methods, but SAX filters
would be building up object instance data during the parse, which would
be returned at the end of each iteration.  Thus, the filter would be
building up a twig, a Simple tree, a DOM-let, or some application 
defined structure (that's being unmarshalled from an XML stream).

I *think* it's a simple hack to the SAX model.  And I *think* there
are some uses to iterator based processing, but I can't seem to 
come up with anything more than a variation of a record processor.

Thoughts anyone?

Z.

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