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Re: Quick Xpath

• To: Uche Ogbuji <uche.ogbuji@f...>
• Subject: Re: Quick Xpath
• From: bob mcwhirter <bob@w...>
• Date: Wed, 17 Jul 2002 23:43:49 -0400 (EDT)
• Cc: Jeni Tennison <jeni@j...>, xml-dev@l...
• In-reply-to: <E17V1kF-00055N-00@m...>

> > Howsabout given:
> > 
> > 	(//foo | //bar)[4]
> > 
> > Would that be the 4th occurrence of either foo or bar, in document 
> > order?  That's just an implementational nightmare.
> 
> I don't see it as an implementation nightmare at all, having implemented 
> XPath.  Yes it would probably be a nightmare for the user, but so would:
> 
> 10: PRINT "I'm cool"
> 20: GOTO 10
> 
> If the user wants to do something silly, it's not XPath's business to get in 
> his way.

Efficiency-speaking, it's a nightmare.  At least the only solution I've come
up with includes walking the entire tree in order to determine the relative
(possibly interleaved) order of your foos and bars.  I guess the argument
is that //x walks the whole tree anyhow, and maybe you could do something
intelligent.

fwiw, sure, if the tree was unchanging and the tree-builder was kind enough
to enumerate the nodes for us, then ordering wouldn't be a pain.  But, for
jaxen, since we support k different object models, the assumptions we can
make are weak, as best.  

	-bob

• Follow-Ups:
  • Re: Quick Xpath
    • From: Amelia A Lewis <amyzing@t...>

• References:
  • Re: Quick Xpath
    • From: Uche Ogbuji <uche.ogbuji@f...>

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