[xquery-talk] Question on expected XQuery return per standards

Geert Josten Geert.Josten at daidalos.nl
Sat Mar 28 13:55:26 PST 2009


Oh, by the way..

I converted the testcases from David Sewell to XSLT 1.0 and 2.0 as well (removed the $xml in front of the Xpath expressions and stored the $xml contents in a file to do the trick), just to see what various XSLT processors would be returning. To my surprise all of the processors I tried were returning p2 only, when running in XSLT 1.0 mode.

Is it true that Xpath 2.0 has changed the meaning of such expressions compared to Xpath 1.0?

Kind regards,
Geert

> -----Original Message-----
> From: talk-bounces at x-query.com 
> [mailto:talk-bounces at x-query.com] On Behalf Of Geert Josten
> Sent: zaterdag 28 maart 2009 12:56
> To: Ronald Bourret; Pavel Minaev
> Cc: talk at xquery.com
> Subject: RE: [xquery-talk] Question on expected XQuery return 
> per standards
> 
> Yes,
> 
> It starts making sense to me now as well. I keep forgetting 
> that $xml/p actually means $xml/child::p. And we all 
> understand intuitively what $xml/p[2] means (especially when 
> reading it as $xml/child::p[2])..
> 
> Just for the sake of completeness, I wrote a simplistic 
> self-contained testsuite with most interesting cases. If 
> someone of you lot could just take a look whether I didn't 
> make any mistakes, that would be appreciated.
> 
> Kind regards,
> Geert
> 
> >
> 
> 
> Drs. G.P.H. Josten
> Consultant
> 
> 
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> 
> > From: talk-bounces at x-query.com
> > [mailto:talk-bounces at x-query.com] On Behalf Of Ronald Bourret
> > Sent: vrijdag 27 maart 2009 21:53
> > To: Pavel Minaev
> > Cc: talk at xquery.com
> > Subject: Re: [xquery-talk] Question on expected XQuery return per 
> > standards
> >
> > Pavel Minaev wrote:
> > > On Fri, Mar 27, 2009 at 12:06 PM, Ronald Bourret 
> > > <rpbourret at rpbourret.com> wrote:
> > >> Hmmm. I would have thought that, in each case, only p2 
> is returned.
> > >>
> > >> According to the spec, "For each item in the input sequence, the 
> > >> predicate expression is evaluated using an inner focus, 
> defined as
> > >> follows: The context item is the item currently being
> > tested against
> > >> the predicate. The context size is the number of items in
> > the input
> > >> sequence. The context position is the position of the
> > context item within the input sequence."
> > >>
> > >> In each case, the input sequence is the result of $xml//p,
> > which is a
> > >> sequence of four p elements. Since the position is the position 
> > >> within this sequence, only p2 is in the second position.
> > >
> > > But it isn't. The standard is very clear that $xml//p expands to 
> > > $xml/descendant-or-self::node()/p. The ordering is also 
> very clear:
> > >
> > >   "Each non-initial occurrence of "//" in a path expression is 
> > > expanded as described in 3.2.4 Abbreviated Syntax, leaving
> > a sequence
> > > of steps separated by "/". This sequence of steps is then 
> evaluated 
> > > from left to right."
> > >
> > > and, obviously, in $xml/descendant-or-self::node()/p[2], 2 is the 
> > > position within the sequence of child nodes of the parent 
> of p, not 
> > > the expression as a whole.
> >
> > Thanks for the clarification. I had to think about it a bit
> > -- the parent isn't obviously involved until you realize that the 
> > parent is a descendant of $xml -- but that now makes sense.
> >
> > -- Ron
> > _______________________________________________
> > talk at x-query.com
> > http://x-query.com/mailman/listinfo/talk
> >
> 
> 


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