RE: Matching a recursive local element structure

Thanks Michael, this gives me something to think about.
-David


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David A. Lee
dlee@xxxxxxxxxxx
http://www.xmlsh.org


-----Original Message-----
From: Michael Kay [mailto:mike@xxxxxxxxxxxx] 
Sent: Saturday, February 05, 2011 9:53 AM
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re:  Matching a recursive local element structure



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