Get all unique elements in a document

xpath2.xsl

<?xml version="1.0"?>
     <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
     <xsl:output method="xml"/>
     <xsl:key name="elements" match="*" use="name()"/>
     <xsl:template match="/">
        <xsl:for-each select="//*[generate-id(.)=generate-id(key('elements',name())[1])]">
            <xsl:sort select="name()"/>
                <xsl:for-each select="key('elements', name())">
                    <xsl:if test="position()=1">
                        <xsl:element name="element">
                            <xsl:attribute name="name">
                                <xsl:value-of select="name()"/>
                            </xsl:attribute>
                            <xsl:attribute name="count">
                                <xsl:value-of select="count(//*[name()=name(current())])"/>
                            </xsl:attribute>
                        </xsl:element>
                    </xsl:if>
                </xsl:for-each>