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[xsl] Re: dynamic XPath?

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"Passin, Tom" <tpassin@xxxxxxxxxxxx> wrote in message
news:5D3C2276FD64424297729EB733ED1F76AF95BB@xxxxxxxxxxxxxxxxxxxxxx
> [Yue Ma]
>
> > This could be a dumb question:
> > Is there a way we can evaluate a dynamic XPath like:
> > <xsl:if test="$tagPath = 'actual value'">
> > The tagPath is something like "//root/tag1/tag2"
> >
> > Seems we can not do it with XSLT 1.0,  right?
> >
>
> Yes we can, depending on how complicated you want the path expression to
> be.

This is quite exaggerated. See below.

> Here is an example -
>
> XML source -
>
> <root>
> <e1>This is e1</e1>
> <e2>This is e2</e2>
> </root>
>
> =========================
>
> Stylesheet -
>
> <xsl:stylesheet version="1.0"
> xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
> <!-- Path to test against -->
> <xsl:variable name='tagPath' select='"/root/e2"'/>
>
> <xsl:template match="/root/*">
> <!-- Create a variable to hold a current path expression -->
> <!-- Standard expression to create a string for the path of the
> current node --> <xsl:variable name='path'>
> /<xsl:for-each select="ancestor::*">
>    <xsl:value-of select="name()"
> />/</xsl:for-each><xsl:value-of select = "name()" />
> </xsl:variable>

What is so "standard" about this expression? It does not uniquely identify
the node -- so it should not qualify as an acceptable solution.


>
> <!-- Test the expression -->
> <xsl:if test='normalize-space($path)=$tagPath'>Got path for
> <xsl:value-of select='name()'/></xsl:if>
> </xsl:template>
>
> </xsl:stylesheet>


This comparison will work in rare cases and will not work in general if
$tagPath evaluates to a single node having preceding siblings.

It will also "work" for more than one node (in case $tagPath evaluates to a
nodeset of two or more nodes) and most probably is not what the author of
the original message wanted.



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Cheers,

Dimitre Novatchev.
http://fxsl.sourceforge.net/ -- the home of FXSL




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