group adjacent with constraints? - grouping

Question

I'm having an issue while using group-adjacent. Below a simplified XML snippet :
<Paras>
<Para tag="Bind">
<Content>some standalone Bind data</Content>
</Para>
<Para tag="L3">
<Content>some header data</Content>
</Para>
<Para tag="BStep.n=1">
<Content>some data</Content>
</Para>
<Para tag="Bind">
<Content>some data</Content>
</Para>
<Para tag="BStep.n+">
<Content>some data</Content>
</Para>
<Para tag="BStep.n+">
<Content>some data</Content>
</Para>
<Para tag="Bind">
<Content>some data</Content>
</Para>
<Para tag="Bind">
<Content>some data</Content>
</Para>
<Para tag="L1">
<Content>some header</Content>
</Para>
<Para tag="BBox.n=1">
<Content>some data</Content>
</Para>
<Para tag="BBox.n+">
<Content>some data</Content>
</Para>
<Para tag="Bind">
<Content>some data</Content>
</Para>
<Para tag="BBox.n+">
<Content>some data</Content>
</Para>
<Para tag="Bind">
<Content>some data</Content>
</Para>
<Para tag="L2">
<Content>some header</Content>
</Para>
</Paras>
What I like to get after final transformation is something as below :
<Paras>
<Para tag="Bind">
<Content>some standalone Bind data</Content>
</Para>
<Para tag="L3">
<Content>some header data</Content>
</Para>
<StepGroup>
<Steps>
<Para tag="BStep.n=1">some data</Para>
<Para tag="Bind">some data</Para>
</Steps>
<Steps>
<Para tag="BStep.n+">some data</Para>
</Steps>
<Steps>
<Para tag="BStep.n+">some data</Para>
<Para tag="Bind">some data</Para>
<Para tag="Bind">some data</Para>
</Steps>
</StepGroup>
<Para tag="L1">
<Content>some header</Content>
</Para>
<BoxGroup>
<Steps>
<Para tag="BBox.n=1">some data</Para>
<Para tag="BBox.n+">some data</Para>
<Para tag="Bind">some data</Para>
</Steps>
<Steps>
<Para tag="BBox.n+">some data</Para>
<Para tag="Bind">some data</Para>
</Steps>
</BoxGroup>
<Para tag="L2">
<Content>some header</Content>
</Para>
</Paras>
Or, to make it a bit textual : All 'bstep' type of tags and 'bind' tags that are adjacent to each other should be grouped in a StepGroup Element, and also all 'bblock' type of tags that are adjacent, including Bind tags, should be grouped in a 'BoxGroup' element.
I used following xslt (only partly shown) :
<!-- Some data above this left out ... -->
<xsl:for-each-group select="current-group()" group-adjacent="#tag='BStep.boxnmb.n=1' or #tag='BStep.boxnmb.n+' or #tag='Bind' or #tag='BStep.nobox' ">
<xsl:choose>
<xsl:when test="current-grouping-key()">
<StepGroup>
<!-- do some stuff with group / not included now -->
<xsl:apply-templates select="current-group()"/>
</StepGroup>
</xsl:when>
<xsl:otherwise>
<xsl:for-each-group select="current-group()" group-adjacent="#tag='BBox.n=1' or #tag='BBox.n+' or #tag='Bind'">
<xsl:choose>
<xsl:when test="current-grouping-key()">
<BoxGroup>
<xsl:apply-templates select="current-group()"/>
</BoxGroup>
</xsl:when>
This works partly, but as I have 'Bind' tags in both types of adjacent groups I need to be able to modify the group-adjacent keys so that for the 'StepGroup' only 'Binds' are included where the element has a 'Step type' tag, and for the 'BoxGroup' only 'Binds' where the previous element has a 'Box type' tag. I've tried some things but all resulting in nice error messages, so I hope someone can point me in the right direction here.

Answer 1

I don't fully understand your requirements, here is some partial solution
<xsl:stylesheet
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="2.0">
<xsl:strip-space elements="*"/>
<xsl:output indent="yes"/>
<xsl:template match="#* | node()">
<xsl:copy>
<xsl:apply-templates select="#* , node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="Paras">
<xsl:copy>
<xsl:for-each-group select="Para" group-adjacent="matches(#tag, 'BStep|Bind')">
<xsl:choose>
<xsl:when test="current-grouping-key()">
<StepGroup>
<xsl:for-each-group select="current-group()" group-starting-with="Para[matches(#tag, 'BStep')]">
<Step>
<xsl:apply-templates select="current-group()"/>
</Step>
</xsl:for-each-group>
</StepGroup>
</xsl:when>
<xsl:otherwise>
<xsl:for-each-group select="current-group()" group-adjacent="matches(#tag, 'BBox|Bind')">
<xsl:choose>
<xsl:when test="current-grouping-key()">
<BoxGroup>
<xsl:apply-templates select="current-group()"/>
</BoxGroup>
</xsl:when>
<xsl:otherwise>
<xsl:apply-templates select="current-group()"/>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each-group>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each-group>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
[edit]
Here is an adaption of the first stylesheet that should do the first level of grouping as you asked for:
<xsl:stylesheet
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="2.0">
<xsl:strip-space elements="*"/>
<xsl:output indent="yes"/>
<xsl:template match="#* | node()">
<xsl:copy>
<xsl:apply-templates select="#* , node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="Paras">
<xsl:copy>
<xsl:for-each-group select="Para"
group-adjacent="matches(#tag, 'BStep|Bind')
and (self::Para[matches(#tag, 'BStep')]
or preceding-sibling::*[not(matches(#tag, 'Bind'))][1][self::Para[matches(#tag, 'BStep')]])">
<xsl:choose>
<xsl:when test="current-grouping-key()">
<StepGroup>
<xsl:for-each-group select="current-group()" group-starting-with="Para[matches(#tag, 'BStep')]">
<Step>
<xsl:apply-templates select="current-group()"/>
</Step>
</xsl:for-each-group>
</StepGroup>
</xsl:when>
<xsl:otherwise>
<xsl:for-each-group select="current-group()" group-adjacent="matches(#tag, 'BBox|Bind')">
<xsl:choose>
<xsl:when test="current-grouping-key()">
<BoxGroup>
<xsl:apply-templates select="current-group()"/>
</BoxGroup>
</xsl:when>
<xsl:otherwise>
<xsl:apply-templates select="current-group()"/>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each-group>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each-group>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
When I apply that with Saxon 9 to your input document I get
<Paras>
<StepGroup>
<Step>
<Para tag="BStep.n=1">
<Content>some data</Content>
</Para>
<Para tag="Bind">
<Content>some data</Content>
</Para>
</Step>
<Step>
<Para tag="BStep.n+">
<Content>some data</Content>
</Para>
</Step>
<Step>
<Para tag="BStep.n+">
<Content>some data</Content>
</Para>
<Para tag="Bind">
<Content>some data</Content>
</Para>
<Para tag="Bind">
<Content>some data</Content>
</Para>
</Step>
</StepGroup>
<Para tag="L1">
<Content>some header</Content>
</Para>
<BoxGroup>
<Para tag="BBox.n=1">
<Content>some data</Content>
</Para>
<Para tag="BBox.n+">
<Content>some data</Content>
</Para>
<Para tag="Bind">
<Content>some data</Content>
</Para>
<Para tag="BBox.n+">
<Content>some data</Content>
</Para>
<Para tag="Bind">
<Content>some data</Content>
</Para>
</BoxGroup>
<Para tag="L2">
<Content>some header</Content>
</Para>
</Paras>
I realize this is not yet a final solution but I have so far not understood what defines the grouping inside of a BoxGroup. Maybe you can explain that in more detail or you can fix that part yourself.