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Re: [xsl] Matching a recursive local element structure


Subject: Re: [xsl] Matching a recursive local element structure
From: Michael Kay <mike@xxxxxxxxxxxx>
Date: Sat, 05 Feb 2011 14:53:23 +0000

I think that it's reasonably easy, from a given global element declaration, to construct a list of possible paths to descendents of that element, where the paths are in the form of regular expressions, for example HTML/BODY/(LIST/ITEM)*. It's also not a hard problem to determine whether a particular element matches one of these regular expressions. The tough bit is translating these regular expressions into XSLT match patterns.

But if you allow predicates in your patterns, there would seem to be at least two ways of doing it. One is to use regular expressions directly:

match="*[matches(string-join(ancestor::*/local-name(),'/'), 'HTML/BODY/(LIST/ITEM)*')]"

The other is for the predicate to include a call to a recursive function - I haven't worked out the details of what it might look like, but it seems clear enough that it's possible (it would be easier if there were a more straightforward way of writing a function that tests whether an element matches a given pattern).

Can it be done without predicates? I think almost certainly not.

Note: all of this assumes the absence of wildcards in the schema.

Michael Kay
Saxonica


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