What are the potential problems with the filtering approach? What is the
"stopping problem"? If I understand this correctly it involves converting an
xslt file into a stateful sax event processor. The end result would seem to be
similar to the best possible results achievable with the pruning approach.
Edward Middleton
Xalan is capable of "streaming processing".
The interesting challenge is to work out when you can discard parts of
the tree that won't be needed again. I think this could be done quite
easily for a small class of very simple stylesheets, but the general
problem is quite hard.
That's been our conclusion. XSLT's semantics require at least the
appearance of having the whole document in memory at once. Figuring out
how to reduce
The terminology Xalan uses for these issues:
Filtering: An optimization consisting of not building portions of the
source model which stylesheet analysis proves will never be referenced by
the stylesheet. Conceptually straightforward, but runs into the "stopping
problem" to some extent; may be hard to apply generally. May require some
rewriting of the stylesheet and/or retaining of "stub" branches of the
tree to avoid breaking XPaths. NOT IMPLEMENTED at this time.
XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list