[xsl] Recursive grouping won't recurse...

Subject: [xsl] Recursive grouping won't recurse...
From: "Hunsberger, Peter" <Peter.Hunsberger@xxxxxxxxxx>
Date: Thu, 4 Jul 2002 12:15:21 -0500
I'm still shaky on grouping with keys so I've probably missed something
obvious, but I can't get a grouping to work when it has to group on a
recursive structure.  The input looks essentially like the following:

	<list>
	   <a type="1" flag="false"/>
	   <b type="2" flag="false"/>
	   <c type="3" flag="false">
	      <d type="4" flag="true"/>
	      <e type="4" flag="true"/>
	      <f type="5" flag="true"/>
	     <g type="5" flag="true"/>
	   </c>
	</list>
	<list>
	   <a type="1" flag="false"/>
	   <b type="2" flag="false"/>
	   <c type="3" flag="false">
	      <d type="7" flag="false">
	         <e type="4" flag="true"/>
	         <e type="4" flag="true"/>
	      </d>
	   </c>
	</list>

Where, if there are adjacent nodes with the same type than the flag will be
true, otherwise the flag will always be false.  It could be possible for
adjacent nodes to have the same type with the flag set to false. The same
structure could go many more levels deep than shown here. The desired output
is

	<list>
	   <a type="1" flag="false"/>
	   <b type="2" flag="false"/>
	   <c type="3" flag="false">
	      <group>
	         <d type="4" flag="true"/>
	         <e type="4" flag="true"/>
                    </group>
	      <group>
	         <f type="5" flag="true"/>
	        <g type="5" flag="true"/>
	      </group>
	   </c>
	</list>
	<list>
	   <a type="1" flag="false"/>
	   <b type="2" flag="false"/>
	   <c type="3" flag="false">
	      <d type="7" flag="false">
	         <group>
	            <e type="4" flag="true"/>
	            <e type="4" flag="true"/>
	         </group>
	      </d>
	   </c>
	</list>

Where any adjacent nodes of the same type and with "flag" = true are
enclosed in a group.  The XSLT I have resembles the following (extracted
from a larger XSLT with other things going on):

<xsl:key select="." name="menus" match="*" use="@type"/>

<xsl:template match="list">
   <xsl:apply-templates select="." mode="menu"/>
</xsl:template>

<xsl:template match="*" mode="menu">
   <xsl:for-each select="*[generate-id() = generate-id(key('menus',
@type))]">
      <xsl:choose>
         <xsl:when test="@flag='true'">
            <group>
               <xsl:copy select=".">
                  <xsl:apply-templates select="@* | text()"/>
                  <xsl:apply-templates select="." mode="menu"/>
               </xsl:copy>
               <xsl:for-each
select="current()/following-sibling::*[current()/@type = @type]">
                  <xsl:copy select="current()">
                     <xsl:apply-templates select="@* | text()"/>
                     <xsl:apply-templates select="." mode="menu"/>
                  </xsl:copy>
               </xsl:for-each>
            </group>
         </xsl:when>
         <xsl:otherwise>
            <xsl:copy select=".">
               <xsl:apply-templates select="@* | text()"/>
               <xsl:apply-templates select="." mode="menu"/>
            </xsl:copy>
            <xsl:for-each
select="current()/following-sibling::*[current()/@type = @type]">
               <xsl:copy select="current()">
                  <xsl:apply-templates select="@* | text()"/>
                  <xsl:apply-templates select="." mode="menu"/>
               </xsl:copy>
            </xsl:for-each>
         </xsl:otherwise>
      </xsl:choose>
   </xsl:for-each>
</xsl:template>

This will produce the desired results for a first level group (as in the
first list), but does not produce the desired results for a second level
group (as in the second list).  The issue is, I'm sure, with the way the key
works, but I'm not clear what the problem is?  

I've also tried doing the same thing with using named templates instead of
modes with the same results.  I'll have to add additional case handling
templates once I've got this working so I'd rather stick with modes if
possible...

BTW, is there a nice way to say "self and siblings" so that you don't have
to copy the current node and then copy the siblings?

Peter Hunsberger

Phone: 901-495-5252
E-mail: Peter.Hunsberger@xxxxxxxxxx


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