Xslt transform & grouping, Using the Muenchian Method?

Hi,

I would like to group following, by attribute Title, and then filter
by attribute filter="food". Title-attribute exists in both Document
and Article elements.

That is, groups should be created based on attribute Title in Document
element, and filtered by attribute e.g. filter="food".

Currently I am using grouping and filtering in following stylesheet.

All other elements, where filter != "food" should be ignored.
Filter is global parameter.

Thank you!


Some help on the way:

XSL:

<?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" version="1.0" encoding="UTF-8" indent="yes"/>

<xsl:key name="by-info" match="Article" use="@info"/>

<xsl:param name="filter" select="'food'"/>

<xsl:template match="Documents">
        <Documents>
                <xsl:for-each select="Document[(_at_)filter='' or
@filter=$filter]/Article[generate-id()=generate-id(key('by-info',@info)[(_at_)filter=$filter])]">
                        <Document name="{(_at_)info}">
                                <xsl:copy-of 
select="key('by-info',@info)[(_at_)filter=$filter]"/>
                        </Document>
                </xsl:for-each>
        </Documents>
</xsl:template>

</xsl:stylesheet>


XML:

<Documents>
        <Document title="1" chapter="1" href="file1.xml" filter="food">
                <Article title="1.1" info="sub" filter="food"/>
                <Article title="1.2" info="main" filter="food"/>
        </Document>
        <Document title="2" chapter="2" href="file2.xml" filter="drink">
                <Article title="2.1" info="sub" filter="drink"/>
                <Article title="2.2" info="main" filter="food"/>
        </Document>
        <Document title="3" chapter="3" href="file2.xml" filter="">
                <Article title="3.1" info="sub" filter="drink"/>
                <Article title="3.2" info="child" filter=""/>
        </Document>
</Documents>


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