Re: [xsl] Recursive function problem

[Nic Gibson <nicg@xxxxxxxxxx>]

On Wed, Jun 30, 2010 at 09:46:05AM +0100, Andrew Welch wrote:
> Wow that looks massively complicated for such a simple task!
> Assuming its all necessary and just answering your initial quesion,
> you have:

Thanks andrew. I knew it was something obvious. I'll go round
the back and give myself a good kicking :)

It *is* massively complex because it needs to handle about six
other variants on the same theme. There's a project here (the OUP)
to get content upgraded to a new model. The attribute based
content is part of the new model. However, it has to be converted
back to the original model for various output mechanisms that
can't yet cope with the new ones. So... I had to write the
code to be as generic as I possibly could.

cheers

nic 

> 
>        <name>
>            <xsl:copy-of select='@role'/>
>            <xsl:value-of select='dtg:attributes-to-elements(.,
> $name-attrs, $name-elems)'/>
>        </name>
> 
> ....and that value-of will always return a text node, so if your
> function is returning elements you will get the text value of those
> elements rather than the elements themselves.  If you change it to
> xsl:copy-of instead of value-of you will get the elements.
> 
> 
> cheers
> andrew
> 
> 
> 
> On 30 June 2010 09:28, Nic Gibson <nicg@xxxxxxxxxx> wrote:
> > Good morning
> >
> > I'm writing a function to be used as part of a content conversion from one
> > DTD to another. The input is in the following form:
> >
> > <names>
> > ? ?<nameGrp role="editor" foreNames="Donald B."
> > ? ? ? ?mainName="Redford">Donald B. Redford</nameGrp>
> > ? ?<nameGrp
> > ? ? ? ?foreNames="Thutmose" foreTitle="III">Thutmose III</nameGrp>
> > </names>
> >
> > and I need to get the output into the form:
> >
> > <names>
> > ? ?<name><fname>Donald B.</fname> <sname>Redford</sname></name>
> > ? ?<name><fname>Thutmose</fname> <ntitle>III</ntitle></name>
> > </names>
> >
> > I've clearly made an error in the function as the output I am getting is
> > on the lines of:
> >
> > <names>
> > ? ?<name>Donald B. Redford</name>
> > ? ?<name>Thutmose III</name>
> > </names>
> >
> > The relevant portions of the stylesheet are:
> >
> > <xsl:stylesheet
> > ? ?xmlns:dtg="http://dtg.oup.com/functions";
> > ? ?xmlns:xsl="http://www.w3.org/1999/XSL/Transform"; xmlns:xd="http://www.oxygenxml.com/ns/doc/xsl";
> > ? ?xmlns:xs="http://www.w3.org/2001/XMLSchema";
> > ? ?version="2.0" exclude-result-prefixes="dtg xd xs">
> >
> > ? ?<xsl:variable name='name-attrs' select="('foreNames', 'mainName', 'foreTitle')"/>
> > ? ?<xsl:variable name='name-elems' select="('fname', 'sname', 'ntitle')"/>
> >
> > ? ?<xsl:template match="/">
> > ? ? ? ?<names>
> > ? ? ? ? ? ?<xsl:apply-templates select='names/nameGrp'/>
> > ? ? ? ?</names>
> > ? ?</xsl:template>
> >
> > ? ?<xsl:template match='nameGrp'>
> > ? ? ? ?<name>
> > ? ? ? ? ? ?<xsl:copy-of select='@role'/>
> > ? ? ? ? ? ?<xsl:value-of select='dtg:attributes-to-elements(., $name-attrs, $name-elems)'/>
> > ? ? ? ?</name>
> > ? ?</xsl:template>
> >
> >
> > ? ?<xsl:function name='dtg:attributes-to-elements'>
> >
> > ? ? ? ?<xsl:param name="element"/>
> > ? ? ? ?<xsl:param name='attributes'/>
> > ? ? ? ?<xsl:param name='elements'/>
> >
> > ? ? ? ?<!-- only the listed attributes, not all of them -->
> > ? ? ? ?<xsl:variable name="attribs" select='$element/@*[local-name(.) = $attributes]'></xsl:variable>
> >
> > ? ? ? ?<!-- we want the attributes reverse sorted by the length of their values. -->
> > ? ? ? ?<xsl:variable name='sorted-attribs' as='item()*'>
> > ? ? ? ? ? ?<xsl:perform-sort select='$attribs' >
> > ? ? ? ? ? ? ? ?<xsl:sort select='string-length(string(.))' order="descending"/>
> > ? ? ? ? ? ?</xsl:perform-sort>
> > ? ? ? ?</xsl:variable>
> >
> > ? ? ? ?<xsl:if test='count($attributes) != count($elements)'>
> > ? ? ? ? ? ?<xsl:message terminate="yes">attributes-to-elements - attribute and element sequences must be the same size.</xsl:message>
> > ? ? ? ?</xsl:if>
> >
> > ? ? ? ?<xsl:value-of select='dtg:attr-to-elem-impl(string($element), $sorted-attribs, $attributes, $elements)'/>
> >
> > ? ?</xsl:function>
> >
> >
> > ? ?<xsl:function name="dtg:attr-to-elem-impl">
> >
> > ? ? ? ?<xsl:param name='source'/>
> > ? ? ? ?<xsl:param name='input-attribs'/>
> > ? ? ? ?<xsl:param name='attrib-names'/>
> > ? ? ? ?<xsl:param name='element-names'/>
> >
> > ? ? ? ?<xsl:variable name='current-val' select='string($input-attribs[1])'/>
> > ? ? ? ?<xsl:variable name='current-name' select='local-name($input-attribs[1])'/>
> > ? ? ? ?<xsl:variable name='index' select='index-of($attrib-names, $current-name)'/>
> > ? ? ? ?<xsl:variable name='output-element' select='$element-names[$index]'/>
> > ? ? ? ?<xsl:variable name="next-attribs" select='$input-attribs[position() gt 1]'/>
> >
> > ? ? ? ?<xsl:choose>
> >
> > ? ? ? ? ? ?<xsl:when test="$source = ''">
> > ? ? ? ? ? ? ? ?<xsl:value-of select="$source"/>
> > ? ? ? ? ? ?</xsl:when>
> >
> > ? ? ? ? ? ?<xsl:when test="count($input-attribs) = 0">
> > ? ? ? ? ? ? ? ?<xsl:value-of select="$source"/>
> > ? ? ? ? ? ?</xsl:when>
> >
> > ? ? ? ? ? ?<xsl:when test="contains($source, $current-val)">
> >
> > ? ? ? ? ? ? ? ?<xsl:variable name='new-element'>
> > ? ? ? ? ? ? ? ? ? ?<xsl:element name="{$output-element}"><xsl:value-of select="$current-val"/></xsl:element>
> > ? ? ? ? ? ? ? ?</xsl:variable>
> >
> > ? ? ? ? ? ? ? ?<xsl:variable name='before' select="substring-before($source, $current-val)"/>
> > ? ? ? ? ? ? ? ?<xsl:variable name='after' select="substring-after($source, $current-val)"/>
> >
> > ? ? ? ? ? ? ? ?<xsl:variable name='result-before'
> > ? ? ? ? ? ? ? ? ? ?select="dtg:attr-to-elem-impl($before, $next-attribs, $attrib-names, $element-names)"/>
> > ? ? ? ? ? ? ? ?<xsl:variable name='result-after'
> > ? ? ? ? ? ? ? ? ? ?select="dtg:attr-to-elem-impl($after, $next-attribs, $attrib-names, $element-names)"/>
> >
> > ? ? ? ? ? ? ? ?<xsl:sequence select="($result-before, $new-element, $result-after)"/>
> >
> > ? ? ? ? ? ?</xsl:when>
> >
> > ? ? ? ? ? ?<xsl:otherwise>
> > ? ? ? ? ? ? ? ?<xsl:sequence select="dtg:attr-to-elem-impl($source, $next-attribs, $attrib-names, $element-names)"/>
> > ? ? ? ? ? ?</xsl:otherwise>
> >
> > ? ? ? ?</xsl:choose>
> >
> > ? ?</xsl:function>
> >
> > </xsl:stylesheet>
> >
> > The large number of variables is due to my having traced through this in the oXygen debugger.
> > I've seen (in the degugger) that $new-element does contain the element created but it
> > appears to be lost before the result is generated.
> >
> > I'm pretty sure the error is in either the variable (new-element) that should be
> > creating the element or in the xsl:sequence instructions. However, I'm having a failing
> > to see the wood for the trees moment. Any pointers would be gratefully received.
> >
> > By the way the recursion for result-before and result-after shoudl be safe as I know
> > that the content of each attribute can only occur once in the text.
> >
> > cheers
> >
> > nic
> >
> >
> 
> 
> 
> -- 
> Andrew Welch
> http://andrewjwelch.com
> Kernow: http://kernowforsaxon.sf.net/