> > 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.
> 
> I think it should be possible to assert by static analysis 
> whether a certain template only accesses descendants of the 
> context node. If this can be asserted for all templates in 
> the style sheet, and if you can arrange the processing within 
> a template so that nodes are only accessed once locally, you 
> can discard nodes processed by directly called templates from 
> memory. Making such assertions shouldn't be that hard if the 
> XPath expressions within the templates use only nodes form 
> the descendant-or-self axis. 

That's precisely what I meant by "a small class of very simple
stylesheets". I came to the conclusion that there are so few real
stylesheets like this that it's not worth the trouble.

Michael Kay
Software AG
home: Michael.H.Kay@xxxxxxxxxxxx
work: Michael.Kay@xxxxxxxxxxxxxx 


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