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On Monday 06 December 2004 15:44, Michael Kay wrote:
> In the context of streaming, most of the techniques
> described are not very different from those used in the
> better XSLT processors. One big difference is that XSLT
> 1.0 is typically implemented using a dual push/pull
> model: XSLT instructions use a push pipeline to write a
> tree, while XPath expressions use a pull streaming model
> to read data from trees; whereas this paper describes a
> model that uses pull iterators uniformly.
Interesting you picked up this point from that paper. In the
context of the area I have been working in we have
traditionally had two implementations of XPath, one push
and one pull. These have now been unified into a single
implementation that can operate either as pull or push. For
implementation reasons the push does not look much like a
simple SAX filter approach but its a push never the less.
The rational for merging the two was partly functional
needs and partly the difficulty of supporting XPath2 over
two separate implementations.