[xsl] Forming a Tree

["Venkatesh Sutrave" <vmsutrave at rediffmail dot com>]

Hi,
I am trying to form a tree on a raw XML, my input XML looks like 
-

<?xml version="1.0"?>
<Root>
<row BookId="1" BookTitle="abc1" TopicId="1" ParentTopicId="1" 
TopicTitle="Topic1"/>
<row BookId="1" BookTitle="abc1" TopicId="2" ParentTopicId="1" 
TopicTitle="Topic11"/>
<row BookId="1" BookTitle="abc1" TopicId="4" ParentTopicId="4" 
TopicTitle="Topic12"/>
<row BookId="1" BookTitle="abc1" TopicId="3" ParentTopicId="2" 
TopicTitle="Topic21"/>

<row BookId="1" TopicId="1" SiteId="1" SortOrder="0" 
SiteTitle="Site1" />
<row BookId="1" TopicId="2" SiteId="2" SortOrder="0" 
SiteTitle="Site2" />
<row BookId="1" TopicId="3" SiteId="3" SortOrder="0" 
SiteTitle="Site3" />
<row BookId="1" TopicId="4" SiteId="4" SortOrder="1" 
SiteTitle="Site4" />
<row BookId="1" TopicId="4" SiteId="1" SortOrder="0" 
SiteTitle="Site1" />
</Root>

and my XSL is -

<?xml version='1.0'?>
<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>

<xsl:template match="Root">
<TreeNodes>
        <xsl:apply-templates select="row[@BookTitle and 
not(preceding::row/@BookId=@BookId)]" />
</TreeNodes>
</xsl:template>

<xsl:template match="row">
<TreeNode>
        <xsl:variable name="node1" select="."/>
        <xsl:attribute name="BookId"><xsl:value-of 
select="@BookId"/></xsl:attribute>
        <xsl:attribute name="Text"><xsl:value-of 
select="@BookTitle"/></xsl:attribute>

        <!-- Topic node -->
        <xsl:for-each select="//row[@ParentTopicId=@TopicId and 
@BookId=$node1/@BookId and @TopicTitle]">
        <TreeNode>
                <xsl:variable name="node2" select="."/>
                <xsl:attribute name="TopicId"><xsl:value-of 
select="@TopicId"/></xsl:attribute>
                <xsl:attribute name="ParentTopicId"><xsl:value-of 
select="@ParentTopicId"/></xsl:attribute>
                <xsl:attribute name="Text"><xsl:value-of 
select="@TopicTitle"/></xsl:attribute>

                <!-- Sub-Topic1 -->
                <xsl:for-each 
select="//row[@ParentTopicId=$node2/@TopicId and 
@ParentTopicId!=@TopicId and @BookId=$node1/@BookId and 
@TopicTitle]">
                <TreeNode>
                        <xsl:variable name="node3" select="."/>
                        <xsl:attribute 
name="TopicId"><xsl:value-of select="@TopicId"/></xsl:attribute>
                        <xsl:attribute 
name="ParentTopicId"><xsl:value-of 
select="@ParentTopicId"/></xsl:attribute>
                        <xsl:attribute name="Text"><xsl:value-of 
select="@TopicTitle"/></xsl:attribute>

                        <!-- Sub-Topic2 -->
                        <xsl:for-each 
select="//row[@ParentTopicId=$node3/@TopicId and 
@ParentTopicId!=@TopicId and @BookId=$node1/@BookId and 
@TopicTitle]">
                        <TreeNode>
                                <xsl:variable name="node4" 
select="."/>
                                <xsl:attribute 
name="TopicId"><xsl:value-of select="@TopicId"/></xsl:attribute>
                                <xsl:attribute 
name="ParentTopicId"><xsl:value-of 
select="@ParentTopicId"/></xsl:attribute>
                                <xsl:attribute 
name="Text"><xsl:value-of select="@TopicTitle"/></xsl:attribute>

                                <!-- Site -->
                                <xsl:for-each 
select="//row[@BookId=$node4/@BookId and @TopicId=$node4/@TopicId 
and @SiteId]">
                                <xsl:sort select="@SortOrder" 
data-type="number"/>
                                <TreeNode>
                                        <xsl:call-template 
name="SiteDetails">
                                                <xsl:with-param 
name="site" select="."/>
                                        </xsl:call-template>
                                </TreeNode>
                                </xsl:for-each>
                        </TreeNode>
                        </xsl:for-each>

                        <!-- Site -->
                        <xsl:for-each 
select="//row[@BookId=$node3/@BookId and @TopicId=$node3/@TopicId 
and @SiteId]">
                        <xsl:sort select="@SortOrder" 
data-type="number"/>
                        <TreeNode>
                                <xsl:call-template 
name="SiteDetails">
                                        <xsl:with-param 
name="site" select="."/>
                                </xsl:call-template>
                        </TreeNode>
                        </xsl:for-each>
                </TreeNode>
                </xsl:for-each>

                <!-- Site -->
                <xsl:for-each 
select="//row[@BookId=$node2/@BookId and @TopicId=$node2/@TopicId 
and @SiteId]">
                <xsl:sort select="@SortOrder" 
data-type="number"/>
                <TreeNode>
                        <xsl:call-template name="SiteDetails">
                                <xsl:with-param name="site" 
select="."/>
                        </xsl:call-template>
                </TreeNode>
                </xsl:for-each>
        </TreeNode>
        </xsl:for-each>
</TreeNode>
</xsl:template>

<xsl:template name="SiteDetails">
        <xsl:param name="site"/>
        <xsl:attribute name="TopicId"><xsl:value-of 
select="$site/@TopicId"/></xsl:attribute>
        <xsl:attribute name="SiteId"><xsl:value-of 
select="$site/@SiteId"/></xsl:attribute>
        <xsl:attribute name="Text"><xsl:value-of 
select="$site/@SiteTitle"/></xsl:attribute>
</xsl:template>

</xsl:stylesheet>

I am applying transformation using .NET classes.
Can the above XSL optimized to gain performance ?
Can I avoid '//row' to achieve the same?

Thanks in advance.
Venkatesh
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