Re: Tricky transformation task

(list guidelines would suggest that a different subject line would have
been better, for teh archives)

Your suggested output seems to be missing some lines, eg (if I
understand your input) there is an object 4 as one end of link 18 that
isn't listed in your output.

I added an <end/> stop element just to simplify the end of recursion
testing (as it's time to go home, mainly)

<LINKS>
      <LINK ID="2" O1-ID="1" O2-ID="3"/>
      <LINK ID="10" O1-ID="1" O2-ID="11"/>
      <LINK ID="14" O1-ID="11" O2-ID="15"/>
      <LINK ID="18" O1-ID="2" O2-ID="4"/>
      <LINK ID="22" O1-ID="2" O2-ID="8"/>
      <LINK ID="26" O1-ID="8" O2-ID="17"/>
      <end/>
 </LINKS>



$ saxon8 links.xml links.xsl
<?xml version="1.0" encoding="UTF-8"?>
<SUBG-ITEMS xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:d="data:,d">
   <ITEM SUBG-ID="d1e3" ITEM-ID="1" ITEM-TYPE="O" NAME="Object"/>
   <ITEM SUBG-ID="d1e3" ITEM-ID="3" ITEM-TYPE="O" NAME="Object"/>
   <ITEM SUBG-ID="d1e3" ITEM-ID="2" ITEM-TYPE="L" NAME="Link"/>
   <ITEM SUBG-ID="d1e3" ITEM-ID="11" ITEM-TYPE="O" NAME="Object"/>
   <ITEM SUBG-ID="d1e3" ITEM-ID="10" ITEM-TYPE="L" NAME="Link"/>
   <ITEM SUBG-ID="d1e3" ITEM-ID="15" ITEM-TYPE="O" NAME="Object"/>
   <ITEM SUBG-ID="d1e3" ITEM-ID="14" ITEM-TYPE="L" NAME="Link"/>
   <ITEM SUBG-ID="d1e9" ITEM-ID="2" ITEM-TYPE="O" NAME="Object"/>
   <ITEM SUBG-ID="d1e9" ITEM-ID="4" ITEM-TYPE="O" NAME="Object"/>
   <ITEM SUBG-ID="d1e9" ITEM-ID="18" ITEM-TYPE="L" NAME="Link"/>
   <ITEM SUBG-ID="d1e9" ITEM-ID="8" ITEM-TYPE="O" NAME="Object"/>
   <ITEM SUBG-ID="d1e9" ITEM-ID="22" ITEM-TYPE="L" NAME="Link"/>
   <ITEM SUBG-ID="d1e9" ITEM-ID="17" ITEM-TYPE="O" NAME="Object"/>
   <ITEM SUBG-ID="d1e9" ITEM-ID="26" ITEM-TYPE="L" NAME="Link"/>
</SUBG-ITEMS>




<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
		xmlns:d="data:,d"
		xmlns:xs="http://www.w3.org/2001/XMLSchema">
  
  <xsl:output indent="yes"/>

  <xsl:template match="LINKS">
    <xsl:apply-templates select="LINK[1]"/>
  </xsl:template>


  <xsl:template match="LINK">
    <xsl:param name="r" select="()"/>
    <xsl:variable name="ro" select="$r[@ITEM-TYPE='O']"/>
    <xsl:choose>
      <xsl:when test="@O1-ID=$ro/@ITEM-ID">
	<xsl:variable name="L" as="element()">
	  <ITEM SUBG-ID="{$ro[@ITEM-ID=current()/@O1-ID]/@SUBG-ID}" ITEM-ID="{@ID}" ITEM-TYPE="L" NAME="Link"/>
	</xsl:variable>
	<xsl:choose>
	  <xsl:when test="@O2-ID=$ro/@ITEM-ID">
	    <xsl:apply-templates select="following-sibling::*[1]">
	      <xsl:with-param name="r" select="$r/d:join(.,current()/@O1-ID,current()/@O2-ID),$L"/>
	    </xsl:apply-templates>
	  </xsl:when>
	  <xsl:otherwise>
	    <xsl:variable name="O" as="element()">
	      <ITEM SUBG-ID="{$ro[@ITEM-ID=current()/@O1-ID]/@SUBG-ID}" ITEM-ID="{@O2-ID}" ITEM-TYPE="O" NAME="Object"/>
	    </xsl:variable>
	    <xsl:apply-templates select="following-sibling::*[1]">
	      <xsl:with-param name="r" select="$r,$O,$L"/>
	    </xsl:apply-templates>
	  </xsl:otherwise>
	</xsl:choose>
      </xsl:when>
      <xsl:otherwise>
	<xsl:choose>
	  <xsl:when test="@O2-ID=$ro/@ITEM-ID">
	    <xsl:variable name="L" as="element()">
	      <ITEM SUBG-ID="{$ro[@ITEM-ID=current()/@O2-ID]/@SUBG-ID}" ITEM-ID="{@ID}" ITEM-TYPE="L" NAME="Link"/>
	    </xsl:variable>
	    <xsl:variable name="O" as="element()">
	      <ITEM SUBG-ID="{$ro[@ITEM-ID=current()/@O2-ID]/@SUBG-ID}" ITEM-ID="{@O2-ID}" ITEM-TYPE="O" NAME="Object"/>
	    </xsl:variable>
	    <xsl:apply-templates select="following-sibling::*[1]">
	      <xsl:with-param name="r" select="$r,$O,$L"/>
	    </xsl:apply-templates>
	  </xsl:when>
	  <xsl:otherwise>
	    <xsl:variable name="L" as="element()">
	      <ITEM SUBG-ID="{generate-id()}" ITEM-ID="{@ID}" ITEM-TYPE="L" NAME="Link"/>
	    </xsl:variable>
	    <xsl:variable name="O1" as="element()">
	      <ITEM SUBG-ID="{generate-id()}" ITEM-ID="{@O1-ID}" ITEM-TYPE="O" NAME="Object"/>
	    </xsl:variable>
	    <xsl:variable name="O2" as="element()">
	      <ITEM SUBG-ID="{generate-id()}" ITEM-ID="{@O2-ID}" ITEM-TYPE="O" NAME="Object"/>
	    </xsl:variable>
	    <xsl:apply-templates select="following-sibling::*[1]">
	      <xsl:with-param name="r" select="$r,$O1,$O2,$L"/>
	    </xsl:apply-templates>
	  </xsl:otherwise>
	</xsl:choose>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:template>
  
  <xsl:template match="end">
    <xsl:param name="r" select="()"/>
     <SUBG-ITEMS>
       <xsl:perform-sort select="$r">
	 <xsl:sort select="@SUBG-ID"/>
       </xsl:perform-sort>
     </SUBG-ITEMS>
  </xsl:template>


<xsl:function name="d:join">
<xsl:param name="e"/>
<xsl:param name="i1"/>
<xsl:param name="i2"/>
<ITEM>
<xsl:copy-of select="$e/@*"/>
<xsl:if test="$e/@SUBG-ID=$i2">
<xsl:attribute name="SUBG-ID" select="$i1"/>
</xsl:if>
</ITEM>
</xsl:function>

</xsl:stylesheet>

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