RE: positional predicates in XPath vs XQL

As I was saying to Chris, a misunderstanding of section 2.4 of the XPath
specification on predicates.

Howard

> -----Original Message-----
> From: owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> [mailto:owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx]On Behalf Of Michael Kay
> Sent: Saturday, November 24, 2001 3:04 AM
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: RE:  positional predicates in XPath vs XQL
>
>
> No, The XPath query /section/para[1] retrieves the first para element of
> every section. What made you think otherwise?
>
> Mike Kay
>
> > -----Original Message-----
> > From: owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> > [mailto:owner-xsl-list@xxxxxxxxxxxxxxxxxxxxxx]On Behalf Of Howard Katz
> > Sent: 23 November 2001 23:36
> > To: XSL-List@xxxxxxxxxxxxxxxxxxxxxx
> > Subject:  positional predicates in XPath vs XQL
> >
> >
> > I'm implementing an engine that evaluates XPath. I'm
> > currently working on
> > the part of the engine that implements positional predicates. I've
> > previously worked this out for location paths in XQL, but I think the
> > semantics are different in the two languages and want to make sure I
> > understand the differences.
> >
> > In XQL if you say (pretending for the moment that positions
> > start from 1 as
> > they do in XPath, rather than 0):
> >
> >      /section/para[ 1 ]
> >
> > and you have a tree that looks like this:
> >
> > 1  section
> > 2       para
> > 3       para
> > 4  section
> > 5       para
> > 6  section
> > 7       para
> > 8       para
> > 9       para
> >
> > you'll get back this nodeset:
> >
> > <2>, <5>, <7>
> >
> > You can paraphrase this XQL query as saying, "Give me back
> > the 1st child
> > node of each <section> element." Similarly, "/section/para[ 2
> > ]" returns
> > <3>, <8>, and if you say "/section/para[ 3 ]", you get back
> > the single node,
> > <9>.
> >
> > To my understanding, the same location path in XPath only
> > returns a single
> > node, <2>. Is my understanding correct?
> >
> > Howard
> >
> >
> >
> >
> >
> >
> >  XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list
> >
>
>
>  XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list
>
>


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