Re: [xsl] XSL/XPath to generate a list of ancestors?

[Nathan Potter <ndp@xxxxxxxxxxxxxxxxxxxx>]

On May 12, 2008, at 9:13 AM, Michael Kay wrote:

> >      <xsl:template match="*" name="fullNameWorker" mode="fullName">
> >          <xsl:if test=".!=/">
> >              <xsl:apply-templates select=".." mode="fullName"/>
> >              <xsl:if test="..!=/">.</xsl:if>
> >              <xsl:value-of select="@name"/>
> >          </xsl:if>
> >      </xsl:template>
>
> Never use != to compare node identity. It can be very expensive and  
> it gives
> the wrong answer. For example if your document is
>
> <doc><subdoc>
>     ...
>   </subdoc></doc>
>
> then doc and subdoc both compare equal to "/", and if the document  
> is 100Mb
> in size then you will be comparing some very long strings to prove it.
>
> In 2.0, use "is". In 1.0, use generate-id(A)=generate-id(B).

I tried this:

     <xsl:template match="*" name="fullNameWorker" mode="fullName">
        <xsl:if test="generate-id(.)!=generate-id(/)">
            <xsl:apply-templates select=".." mode="fullName"/>
            <xsl:if test="generate-id(..)!=generate-id(/)">.</xsl:if>
            <xsl:value-of select="@name"/>
        </xsl:if>
     </xsl:template>

And it just nuked the stack when I tried to apply the transform:

Exception in thread "main" java.lang.StackOverflowError
	at org.jdom.Verifier.checkXMLName(Verifier.java:604)
	at org.jdom.Verifier.checkAttributeName(Verifier.java:116)
	at org.jdom.Attribute.setName(Attribute.java:360)
	at org.jdom.Attribute.<init>(Attribute.java:228)
	at org.jdom.Attribute.<init>(Attribute.java:276)
	at org.jdom.DefaultJDOMFactory.attribute(DefaultJDOMFactory.java:93)
	at org.jdom.input.SAXHandler.startElement(SAXHandler.java:544)
	at org.xml.sax.helpers.XMLFilterImpl.startElement(XMLFilterImpl.java: 
527)
	at org.jdom.transform.JDOMResult$DocumentBuilder.startElement 
(JDOMResult.java:519)
	at  
com.sun.org.apache.xml.internal.serializer.ToXMLSAXHandler.closeStartTag 
(ToXMLSAXHandler.java:205)
	at  
com.sun.org.apache.xml.internal.serializer.ToXMLSAXHandler.characters 
(ToXMLSAXHandler.java:524)
	at GregorSamsa.constraintTagWorker()
	at GregorSamsa.applyTemplates4()
	at GregorSamsa.applyTemplates4()

(Which leads me to ask: Why is there a Kafka character lurking in my  
XSLT implementation?)

Some how the recursion gets out of control.



Some more context for the XSL:


The goal was that when processing an element I need to generate it's  
linage in a "." separated string. So I need to insert a tag  
containing this lineage string into the element that is being processed/



    <xsl:template name="fullName">
        <fullName>
            <xsl:call-template name="fullNameWorker" />
        </fullName >
    </xsl:template>

    <xsl:template match="*" name="fullNameWorker" mode="fullName">
        <xsl:if test=".!=/">
            <xsl:apply-templates select=".." mode="fullName"/>
            <xsl:if test="..!=/">.</xsl:if>
            <xsl:value-of select="@name"/>
        </xsl:if>
    </xsl:template>

    <xsl:template match="*">
        <myNewNode>
		<xsl:call-template name="fullName">
	</myNewNode>
    </xsl:template>






> Michael Kay
> http://www.saxonica.com/

============================================================
Nathan Potter                 Oregon State University, COAS
ndp at coas.oregonstate.edu   104 Ocean. Admin. Bldg.
541 737 2293 voice            Corvallis, OR   97331-5503
541 737 2064 fax