Or, not operator and if statement : boolean operator « XSLT stylesheet « XML Tutorial

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3. boolean operator

File: Data.xml

<?xml version="1.0"?>
<addressbook>

  <address>
    <name>
      <title>Ms.</title>
      <first-name>Bond</first-name>
      <last-name>Lee</last-name>
    </name>
    <street>707 Main Way</street>
    <city>New York</city>
    <state>ME</state>
    <zip>00218</zip>
  </address>

</addressbook>

File: Transform.xslt
<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:output method="text" indent="no"/>

  <xsl:variable name="newline">
  <xsl:text></xsl:text>
  </xsl:variable>

  <xsl:template match="/">
    <xsl:text>Addresses sorted by zip code</xsl:text>
    <xsl:value-of select="$newline"/>
    <xsl:for-each select="addressbook/address">
      <xsl:sort select="zip"/>
      <xsl:if test="not(preceding-sibling::address) or zip!=preceding-sibling::address[1]/zip">
        <xsl:value-of select="$newline"/>
        <xsl:text>Zip code </xsl:text>
        <xsl:value-of select="zip"/>
        <xsl:text> (</xsl:text>
        <xsl:value-of select="city"/>
        <xsl:text>, </xsl:text>
        <xsl:value-of select="state"/>
        <xsl:text>): </xsl:text>
        <xsl:value-of select="$newline"/>
      </xsl:if>
      <xsl:if test="name/title">
        <xsl:value-of select="name/title"/>
        <xsl:text> </xsl:text>
      </xsl:if>
      <xsl:value-of select="name/first-name"/>
      <xsl:text> </xsl:text>
      <xsl:value-of select="name/last-name"/>
      <xsl:value-of select="$newline"/>
      <xsl:value-of select="street"/>
      <xsl:value-of select="$newline"/>
      <xsl:value-of select="$newline"/>
    </xsl:for-each>
  </xsl:template>
</xsl:stylesheet>


Output:

Addresses sorted by zip codeZip code 00218 (New York, ME): Ms. Bond Lee707 Main Way