codemeit

XSLT 1.0, Join a list of elements’s value with separator

In order to join a sequence with a customized separator in XSLT 1.0, similar to C# function string.Join( array, separator), I’ve come up with a template which takes the sequence and separator as parameter.

Given a sample XML

<?xml version="1.0" encoding="utf-8" ?>
<?xml-stylesheet type="text/xsl" href="ElementJoin.xslt"?>
<Root>
  <Years>
    <int>2008</int>
    <int>2009</int>
    <int>2010</int>
  </Years>
  <Technologies>
    <Java>SUN</Java>
    <Csharp>MS</Csharp>
  </Technologies>
</Root>

Expected output

XSLT (1.0) referenced as ElementJoin.xslt

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:msxsl="urn:schemas-microsoft-com:xslt"
exclude-result-prefixes="msxsl">
  <xsl:output method="text" indent="yes"/>

  <!-- join integer array by separator ',' -->
  <xsl:template match="/Root/Years">
    <xsl:value-of select="local-name()"/>
    <xsl:text>: </xsl:text>
    <xsl:call-template name="join">
      <xsl:with-param name="valueList" select="*"/>
      <xsl:with-param name="separator" select="','"/>
    </xsl:call-template>
    <xsl:text>&#xa;&#xd;</xsl:text>
  </xsl:template>

  <!-- join children elements by separator ' | ' -->
  <xsl:template match="/Root/Technologies">
    <xsl:value-of select="local-name()"/>
    <xsl:text>: </xsl:text>
    <xsl:call-template name="join">
      <xsl:with-param name="valueList" select="*"/>
      <xsl:with-param name="separator" select="' | '"/>
    </xsl:call-template>
    <xsl:text>&#xa;&#xd;</xsl:text>
  </xsl:template>

  <!-- template 'join' accepts valueList and separator -->
  <xsl:template name="join" >
    <xsl:param name="valueList" select="''"/>
    <xsl:param name="separator" select="','"/>
    <xsl:for-each select="$valueList">
      <xsl:choose>
        <xsl:when test="position() = 1">
          <xsl:value-of select="."/>
        </xsl:when>
        <xsl:otherwise>
          <xsl:value-of select="concat($separator, .) "/>
        </xsl:otherwise>
      </xsl:choose>
    </xsl:for-each>
  </xsl:template>
</xsl:stylesheet>

This can be done easily with XPATH 2.0 fn:string-join(sequence, delimiter). However the current .NET only supports XSLT 1.0, XPATH 1.0. For advanced transformation, check out http://www.saxonica.com/documentation/changes/intro/xslt91.html