RE: [xsl] match taste

Subject: RE: [xsl] match taste
From: "Michael Kay" <michael.h.kay@xxxxxxxxxxxx>
Date: Wed, 20 Nov 2002 09:05:56 -0000
> > 
> > Ive just been writing a lot of matches of the form:
> > 
> >   <xsl:template match="node1//node2">
> > 
> > and started to think about if I should be writing
> > 
> >   <xsl:template match="node2[ancestor::node1]">
> > 
> > Im not sure which one is more readable, probably the former,
> > but is there any more technical reason for choosing one over 
> > the other?
> >

I'm afraid the following answer is misinformed.
 
> You cannot compare these two matches.

Yes you can, they are equivalent.

> The first searches node1 and all node2 in the subtree.

Only a very naïve implementation would do it that way.

> The second one searches node2 and lookup the parents.
> Of course the second one is faster, but how do you
> position on parent of node2?

They should perform exactly the same.
> 
> 
> Maybe you want compare 
>   match="//node1//node2" 
> with 
>   match="//node2[ancestor::node1]"?

A leading "//" on a match pattern is completely redundant.

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

> 
> Then both will be inefficient (complete tree search).
> 
> Juergen Zink
> home: zink_softwarearchitekt@xxxxxx
> work: juergen.zink@xxxxxxxxxxxxxxxxxxxx
> 
> 
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