XPath relative to variable's location in source document - xslt

Question

When iterating through the nodes in a node-set variable I want an XPATH 1.0 expression that returns all ancestors of a node (e.g., of $myVariable[7]) -- not the ancestors in the node-set variable, but ancestors in the original document.
I thought one of these would work, but neither does.
select="//*[generate-id()=generate-id($myVariable[7])]/ancestor::*"
select="id(generate-id($myVariable[7]))/ancestor::*"
Am I close?
Edit: It's not central to my question, but I had //ancestor; that extra slash is unnecessary.

Answer 1

Your expression:
//*[generate-id()=generate-id($myVariable[7])]/ancestor::*
is correct.
The reason it is "not working" may be due to the fact that $myVariable[7] doesn't contain what you are expecting.
Here is a simple complete example using the above expression and producing the expected. correct results:
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:variable name="myVariable"
select="/*/*/*/*/num"/>
<xsl:template match="/">
<xsl:for-each select=
"//*[generate-id()
=
generate-id($myVariable[7])
]
/ancestor::*
">
<xsl:value-of select="name()"/>
<xsl:text>
</xsl:text>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
when this transformation is applied on the following XML document:
<a>
<b>
<c>
<nums>
<num>01</num>
<num>02</num>
<num>03</num>
<num>04</num>
<num>05</num>
<num>06</num>
<num>07</num>
<num>08</num>
<num>09</num>
<num>10</num>
</nums>
</c>
</b>
</a>
the wanted, correct result (the names of all ancestors of $myVariable[7]) is produced:
a
b
c
nums