Re: [xsl] Problem using preceding-sibling

Subject: Re: [xsl] Problem using preceding-sibling
From: Jeni Tennison <jeni@xxxxxxxxxxxxxxxx>
Date: Tue, 14 May 2002 16:15:57 +0100
Hi Faroukh,

> I try to get the immediate sibling by checking the position, however
> I get always the first node.
> <xsl:variable name="cpo" select="position()"/>
> <xsl:element name="Preceding_GID">
>   <xsl:value-of select="generate-id(preceding-sibling::node()[position()=
> $cpo - 1])"/>
> </xsl:element>

You're a bit confused about the interaction between axes and the
position() function. The position() function gives you the position of
the context node amongst the other nodes you're looking at. If you did:

  child::Level2[position() = 1]

or the equivalent:


then you'd get the first Level1 child of the context node. If you did:


then you'd get the fifth Level2 descendant of the context node. If you


then you'd get the second following sibling of the context node.

Similarly, if you did:


then you get the immediately preceding sibling of the node
(preceding-sibling is a reverse axis, which means that positional
predicates, like the one hear, count in reverse document order, so you
get the nearest sibling node).

What you need, then, is simply:

    <xsl:value-of select="generate-id(preceding-sibling::node()[1])"/>

Although you could use:

    <xsl:value-of select="generate-id(../node()[position() = $cpo - 1])"/>

if you really wanted (it's likely to be a lot less efficient).

Note that there's no need to use xsl:element to create your elements
if you know what their names are.



Jeni Tennison

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