Subject: Re: [xsl] Getting Unexpected Results from .//* = $set-of-elements From: "G. Ken Holman g.ken.holman@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> Date: Fri, 23 Feb 2018 23:36:37 -0000 |
Your operands of "=" are nodes, and so you are checking the *value* of the elements when you say:
I doubt you wanted the *value* (concatenated string of descendent text nodes), but you probably want the identity.
some $elem in .//* satisfies ( for $each in $elements-to-keep return $elem is $each )
Because of my time limitation I've just thrown this together and haven't tested it ... and I haven't run your data ... but given you have key('elementsById',$id,.) I suspect you are not interested in the string value of each of the elements but their identity.
not.I'm implementing a filtering process where I want to filter out everything except the ancestors of specified elements (user provides a list of IDs to keep), as well as specific subelements of the ancestors (e.g., header elements within HTML sections).
I'm using Saxon PE 9.7.0.19 (as included with Oxygen 19.1) and and XSLT 2 template. The source doc is XHTML:
<?xml version="1.0" encoding="UTF-8"?> .. At the start of my processing I create a variable that is the list of elements to keep:
<xsl:variable name="elements-to-keep" as="element()*" select=" for $id in $element-ids-for-filtering return key('elementsById', $id, .) " />
I've verified that this produces the expected list of elements.
I then filter like so, here in the context of a template that handles html section elements:
<xsl:template mode="filter-by-element-id" match="xhtml:section | xhtml:div" priority="10"> <xsl:param name="elements-to-keep" as="element()*" tunnel="yes"/>
<xsl:choose> <xsl:when test=". = $elements-to-keep"> <xsl:next-match/> </xsl:when> <xsl:when test=".//* = $elements-to-keep"> <xsl:copy> <xsl:apply-templates mode="#current" select="@*, *"/> </xsl:copy> </xsl:when> <xsl:otherwise> <xsl:message>+ [DEBUG] filter-by-element-id: Section does not contain any elements to keep, ignoring it.</xsl:message> </xsl:otherwise> </xsl:choose> </xsl:template>
o;?What I think I'm saying is:
IF current element is in $elements-to-keep, keep it (next match copies it to output) IF any descendant of current element is in $elements-to-keep, process the current element Otherwise ignore the element.
In my test data I have this figure element:
<figure id="x88B6B95AEAD3 <img id="x88B6B95AEADC" /> </figure>
If I specify the ID of the figure, the result is as expected--I get the figure and all of the ancestor sections and nothing else.
However, if I specify the ID of the img element, I get not only the section I want but other sections, because the second <when> in the choice above resolves as true() when it should not.
Through experimentation I determined that the variable is whether or not the element with the ID is an empty element or
If the element is not empty, I get the correct behavior.
If the element is empty, I get the incorrect behavior.
Why would I be getting this behavior?
Could this be a Saxon bug or is there some subtlety in the "=" operator that I'm missing?
What's particularly odd is that I'm getting a false positive from elements that do not have the element in $elements-to-keep as a descendant.
Thanks,
Eliot -- Eliot Kimber http://contrext.com
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