Reverse Find in a string

xml, xslt

Solution

The following is an example of a template that would produce the required output in XSLT 1.0:

<xsl:template name="getExtension">
<xsl:param name="filename"/>

  <xsl:choose>
    <xsl:when test="contains($filename, '.')">
    <xsl:call-template name="getExtension">
      <xsl:with-param name="filename" select="substring-after($filename, '.')"/>
    </xsl:call-template>
    </xsl:when>
    <xsl:otherwise>
      <xsl:value-of select="$filename"/>
    </xsl:otherwise>
  </xsl:choose>
</xsl:template>

<xsl:template match="/">
    <xsl:call-template name="getExtension">
        <xsl:with-param name="filename" select="'http://www.blah.com/path/to/file/media.jpg'"/>
    </xsl:call-template>
</xsl:template>

Problem

I need to be able to find the last occurrence of a character within an element. For example: ``` <mediaurl>http://www.blah.com/path/to/file/media.jpg</mediaurl> ``` If I try to locate it through using `substring-before(mediaurl, '.')` and `substring-after(mediaurl, '.')` then it will, of course, match on the first dot. How would I get the file extension? Essentially, I need to get the file name and the extension from a path like this, but I am quite stumped as to how to do it using XSLT.

Original source