use warnings;
use strict;
use XML::LibXSLT;
use XML::LibXML;

my $source = XML::LibXML->load_xml( string => <<'END_XML' );
<foo>
	<x one="Foo" two="Bar" />
	<x one="Quz" two="Quz" />
</foo>
END_XML

my $style_doc = XML::LibXML->load_xml(
	string => <<'END_XSLT', no_cdata => 1 );
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
	xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<bar>
	<xsl:for-each select="foo/x">
		<xsl:variable name="name1" select="@one" />
		<xsl:variable name="name2" select="@two" />
		<xsl:if test="$name1 = $name2">
			<y><xsl:value-of select="@one"/></y>
		</xsl:if>
	</xsl:for-each>
</bar>
</xsl:template>
</xsl:stylesheet>
END_XSLT

my $xslt = XML::LibXSLT->new();
my $stylesheet = $xslt->parse_stylesheet($style_doc);
my $results = $stylesheet->transform($source);
print $stylesheet->output_as_bytes($results);

__END__

<?xml version="1.0"?>
<bar><y>Quz</y></bar>