Re: [xsl] testing preceding sibling always evaluates true

[Hank Ratzesberger <hankr@xxxxxxxx>]

Thank you Michael.

I just received the 4th edition (it really is hardbound!)
so I could check if anything had changed, but on p. 602 :

 There are three kinds of expressions in XPath 2.0 whose result
 is guaranteed to be a sequence of nodes in document order...

  o Any axis step (even and axis step like <preceding-sibling::*> that
    uses a reverse axis delivers its results in forwards document order)

But, reading on... p. 618

 In effect, the predicate operator <[]> has a higher precedence (it
 binds more tightly) than the path operator </>

That's a bit subtle, but OK, now I know, XPath has an evaluation
precedence to consider.

--Hank


On 07/29/2011 11:19 AM, Michael Kay wrote:
> > I believe the issue is (and I would like some clarification), is that
> > axis steps always return nodes in document order so
> >
> > preceding-sibling::w:p[1]
> >
> > will always return the first paragraph with its TableCaption child.
> >
> > I believe the work around for this, to collect the nodes in search
> > order, is to make them a set,
> >
> > (preceding-sibling::w:p)[1]
> No this is wrong. preceding-sibling::w:p[1] selects the most recent w:p
> element (the last in document order), whereas
> (preceding-sibling::w:p)[1] selects the first in document order.
>
> Michael Kay
> Saxonica


--
Louis (Hank) Ratzesberger
sopac.ucsd.edu