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Re: [xsl] Does the count() function require access to the whole subtree?

2014-01-12 13:28:10


Michael, doesn't the count() function require access to the whole subtree? 
How would a count be conducted by sitting at the top of a subtree? Perhaps 
you meant to say that the count() function is an absorption operation?


If you are evaluating count() or exists() on a sequence of nodes S, then when 
you encounter a node N that is a member of this sequence you know its impact on 
the result as soon as you see its start tag; you do not need to look at its 
subtree. This makes it different from, say, sum() or "=". This means that the 
existence of overlapping nodes within S is no problem for count() or exists(), 
whereas it is a problem for sum() or "=".

Michael Kay
Saxonica
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