XSLT key only returns a value once - xslt

Question

I think I'm missing something obvious here but here goes. I have the below xml and I need to group the KEY nodes of the matched instances together. This is specified by the match attribute and it can contain more than one item number. There can be any number of ITEM nodes and any number of KEY nodes. Also, there is no limit to the depth of the ITEM nodes. And, the matched instances need not be under the same parent. I'm also limited to XSLT 1.0 and the Microsoft parser.
<?xml version="1.0" encoding="utf-8" ?>
<ITEM number='1'>
<ITEM number='2'>
<ITEM number='3' match='5,11'>
<KEY name='key1' value='x' />
<KEY name='key2' value='y' />
<KEY name='key3' value='z' />
<ITEM number ='4' />
</ITEM>
<ITEM number='5' match='3,11'>
<KEY name='key1' value='x' />
<KEY name='key2' value='y' />
<KEY name='key3' value='z' />
</ITEM>
<ITEM number='6' match='10'>
<KEY name='key1' value='x' />
<KEY name='key2' value='y' />
<KEY name='key4' value='a' />
</ITEM>
<ITEM number='7' />
<ITEM number='8'>
<KEY name='key1' value='x' />
</ITEM>
</ITEM>
<ITEM number='9'>
<ITEM number='10' match='6'>
<KEY name='key1' value='x' />
<KEY name='key3' value='z' />
<KEY name='key5' value='b' />
</ITEM>
</ITEM>
<ITEM number='11' match='3,5'>
<KEY name='key2' value='y' />
<KEY name='key3' value='z' />
</ITEM>
</ITEM>
My expected result would look something like this...
<?xml version="1.0" encoding="utf-8" ?>
<Result>
<Group number="1" />
<Group number="2" />
<Group number="3,5,11">
<KEY name='key1' value='x' />
<KEY name='key2' value='y' />
<KEY name='key3' value='z' />
</Group>
<Group number="4" />
<Group number="6,10">
<KEY name='key1' value='x' />
<KEY name='key2' value='y' />
<KEY name='key3' value='z' />
<KEY name='key4' value='a' />
<KEY name='key5' value='b' />
</Group>
<Group number="7" />
<Group number="8">
<KEY name='key1' value='x' />
</Group>
<Group number="9" />
</Result>
What I actually get is...
<?xml version="1.0" encoding="utf-8"?>
<Result>
<Group number="1" />
<Group number="2" />
<Group number="3,5,11">
<KEY name="key1" value="x" />
<KEY name="key2" value="y" />
<KEY name="key3" value="z" />
</Group>
<Group number="4" />
<Group number="6,10">
<KEY name="key4" value="a" />
<KEY name="key5" value="b" />
</Group>
<Group number="7" />
<Group number="8" />
<Group number="9" />
</Result>
I'm using a key and it looks like once I access that particular value from the key function, I cannot access it again. Group number 6,10 should contain all 5 keys but is missing the first 3 which are already present in group number 3,5. Similarly for group number 8, it should contain 1 key. I've used recursion to skip over the matched instances but I don't think there is any issue over there, it seems to be related to the key functionality. I've attached my xslt below, please take a look and tell me what I'm doing wrong. Any tips for performance improvements are also appreciated :)
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:msxsl="urn:schemas-microsoft-com:xslt" exclude-result-prefixes="msxsl">
<xsl:output method="xml" indent="yes"/>
<xsl:key name="kKeyByName" match="KEY" use="#name" />
<xsl:template name="ProcessItem">
<!--pItemsList - node set containing items that need to be processed-->
<xsl:param name="pItemsList" />
<!--pProcessedList - string containing processed item numbers in the format |1|2|3|-->
<xsl:param name="pProcessedList" />
<xsl:variable name="vCurrItem" select="$pItemsList[1]" />
<!--Recursion exit condition - check if we have a valid Item-->
<xsl:if test="$vCurrItem">
<xsl:variable name="vNum" select="$vCurrItem/#number" />
<!--Skip processed instances-->
<xsl:if test="not(contains($pProcessedList, concat('|', $vNum, '|')))">
<xsl:element name="Group">
<!--If the item is matched with another item, only the distinct keys of the 2 should be displayed-->
<xsl:choose>
<xsl:when test="$vCurrItem/#match">
<xsl:attribute name="number">
<xsl:value-of select="concat($vNum, ',', $vCurrItem/#match)" />
</xsl:attribute>
<xsl:for-each select="(//ITEM[#number=$vNum or #match=$vNum]/KEY)[generate-id(.)=generate-id(key('kKeyByName', #name)[1])]">
<xsl:apply-templates select="." />
</xsl:for-each>
</xsl:when>
<xsl:otherwise>
<xsl:attribute name="number">
<xsl:value-of select="$vNum" />
</xsl:attribute>
<xsl:apply-templates select="KEY" />
</xsl:otherwise>
</xsl:choose>
</xsl:element>
</xsl:if>
<!--Append processed instances to list to pass on in recursive function-->
<xsl:variable name="vNewList">
<xsl:value-of select="$pProcessedList" />
<xsl:value-of select="concat($vNum, '|')" />
<xsl:if test="$vCurrItem/#match">
<xsl:value-of select="concat($vCurrItem/#match, '|')" />
</xsl:if>
</xsl:variable>
<!--Call template recursively to process the rest of the instances-->
<xsl:call-template name="ProcessItem">
<xsl:with-param name="pItemsList" select="$pItemsList[position() > 1]" />
<xsl:with-param name="pProcessedList" select="$vNewList" />
</xsl:call-template>
</xsl:if>
</xsl:template>
<xsl:template match="KEY">
<xsl:copy>
<xsl:copy-of select="#*|node()" />
</xsl:copy>
</xsl:template>
<xsl:template match="/">
<xsl:element name="Result">
<xsl:call-template name="ProcessItem">
<xsl:with-param name="pItemsList" select="//ITEM" />
<xsl:with-param name="pProcessedList" select="'|'" />
</xsl:call-template>
</xsl:element>
</xsl:template>
</xsl:stylesheet>

Answer 1

IF there is only one match or none to each item you can give the following xslt a try:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" >
<xsl:output method="xml" indent="yes" />
<xsl:strip-space elements="*"/>
<xsl:key name="kItemNr" match="ITEM" use="#number" />
<xsl:key name="kNumberKey" match="KEY" use="concat(../#number, '|', #name )" />
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="ITEM">
<xsl:if test="not(preceding::ITEM[#number = current()/#match])" >
<Group>
<xsl:attribute name="number">
<xsl:value-of select="#number"/>
<xsl:if test="#match" >
<xsl:text>,</xsl:text>
<xsl:value-of select="#match"/>
</xsl:if>
</xsl:attribute>
<xsl:variable name="itemNr" select="#number"/>
<xsl:apply-templates select="KEY | key('kItemNr',#match )/KEY[
not (key('kNumberKey', concat($itemNr, '|', #name) ) )] ">
<xsl:sort select="#name"/>
</xsl:apply-templates>
</Group>
</xsl:if>
</xsl:template>
<xsl:template match="/" >
<Result>
<xsl:for-each select="//ITEM[count(. | key('kItemNr',number ) ) = 1 ]" >
<xsl:apply-templates select="." />
</xsl:for-each>
</Result>
</xsl:template>
</xsl:stylesheet>
Which will generate the following output:
<?xml version="1.0"?>
<Result>
<Group number="1"/>
<Group number="2"/>
<Group number="3,5">
<KEY name="key1" value="x"/>
<KEY name="key2" value="y"/>
<KEY name="key3" value="z"/>
</Group>
<Group number="4"/>
<Group number="6,10">
<KEY name="key1" value="x"/>
<KEY name="key2" value="y"/>
<KEY name="key3" value="z"/>
<KEY name="key4" value="a"/>
<KEY name="key5" value="b"/>
</Group>
<Group number="7"/>
<Group number="8">
<KEY name="key1" value="x"/>
</Group>
<Group number="9"/>
</Result>
Update because of changed request:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" >
<xsl:output method="xml" indent="yes"/>
<xsl:key name="kItemNr" match="ITEM" use="#number" />
<xsl:template match="#*|node()">
<xsl:copy >
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="ITEM">
<xsl:variable name="matchStr" select=" concat(',', current()/#match, ',')"/>
<xsl:if test="not(preceding::ITEM[ contains($matchStr, concat(',', #number, ',') )])" >
<Group>
<xsl:attribute name="number">
<xsl:value-of select="#number"/>
<xsl:if test="#match" >
<xsl:text>,</xsl:text>
<xsl:value-of select="#match"/>
</xsl:if>
</xsl:attribute>
<xsl:apply-templates select="(KEY |
//ITEM[
contains( $matchStr, concat(',', #number, ',') )
]/KEY[
not((preceding::ITEM[
contains( $matchStr, concat(',', #number, ',') )
] | current() )/KEY/#name = #name)
]) ">
<xsl:sort select="#name"/>
</xsl:apply-templates>
</Group>
</xsl:if>
</xsl:template>
<xsl:template match="/" >
<Result>
<xsl:for-each select="//ITEM[count(. | key('kItemNr',number ) ) = 1 ]" >
<xsl:apply-templates select="." />
</xsl:for-each>
</Result>
</xsl:template>
</xsl:stylesheet>
This may be quite slow for bigger input data but any way.