> Is anyone aware of publically available implementations of XPath,
> XQuery, and XSLT that operate in a streaming manner i.e. in a single
> pass over the input.
I don't think there are any. In the general case it's extremely
difficult to do. In fact, I don't think it's possible: the best you can
do is to discard the parts of the tree that you aren't going to need.
(Which might amount to the same thing in some cases)
> The academic literature mentions a number of systems that do not
> seem to be downloadable.
>
Academic papers have a nasty habit of abstracting away those aspects of
a problem that make it difficult to solve. I read one paper that talked
about rewriting path expressions to avoid use of the reverse axes, which
simplified the problem by ignoring positional predicates!
Michael Kay
