Re: [xsl] curious behavior of select= and predicates

[Jeni Tennison <jeni@xxxxxxxxxxxxxxxx>]

Hi Robert,

> First oddity -- i had always understood that "self::node()" could be
> abbreviated as just ".". but if i replace the select expression with
> ".[displacement]", i get the error

A predicate is only allowed in a Step, not with an AbbreviatedStep.
"." is not textually replaced by "self::node()".

> I want the "car" template to return its string value only if it's
> the third in context position. (again, a weird thing to do but humor
> me.) shouldn't i be able to write:
>
> <xsl:template match="car">
>  <xsl:value-of select="self::node()[position() = 3]"/>  # just pos 3
> </xsl:template>

No. Within the predicate, the position() function returns the position
of the context node (the node that you're testing with the predicate)
amongst the nodes that you've selected in the step. You've only
selected one node with the step, the <car> element itself. The
position of the <car> element that you're testing with the predicate
is always 1 because you only select one of them.

To test the position of the <car> element amongst the <car> elements
that are having templates applied to them, use the position() function
outside the predicate, where the current node list is made up of those
<car> elements. Use:

<xsl:template match="car">
  <xsl:if test="position() = 3">
    <xsl:value-of select="." />
  </xsl:if>
</xsl:template>

Cheers,

Jeni

---
Jeni Tennison
http://www.jenitennison.com/


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