File: Data.xml
<?xml version="1.0" encoding="utf-8"?>
<data>
<AAA>
<BBB id="b1">
<CCC name="q" size="12"/>
<EEE id="e1">
<SSS/>
</EEE>
<CCC weight="45"/>
<CCC/>
</BBB>
</AAA>
<AAA>
<EEE id="e2"/>
<CCC>
<DDD/>
<DDD/>
</CCC>
</AAA>
</data>
File: Transform.xslt
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet
version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="/">
<xsl:for-each select="/descendant::*">
<xsl:variable name="pos" select="position()"/>
<xsl:variable name="name" select="name()"/>
<xsl:if test="not(/descendant::*[position() < $pos and name()= $name])">
<Paragraph>
<xsl:value-of select="$name"/>
<xsl:text> [</xsl:text>
<xsl:for-each select="//*[name()=$name]/*">
<xsl:variable name="p" select="position()"/>
<xsl:if test="not(//*[name()=$name]/*[position()< $p and name()=name(current())])">
<xsl:value-of select="name()"/>
<xsl:text>, </xsl:text>
</xsl:if>
</xsl:for-each>
<xsl:text>]</xsl:text>
</Paragraph>
</xsl:if>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>
Output:
<?xml version="1.0" encoding="UTF-8"?><Paragraph>data [AAA, ]</Paragraph><Paragraph>AAA [BBB, ]</Paragraph><Paragraph>BBB [CCC, EEE, ]</Paragraph><Paragraph>CCC [DDD, ]</Paragraph><Paragraph>EEE [SSS, ]</Paragraph><Paragraph>SSS []</Paragraph><Paragraph>DDD []</Paragraph>