Symphony.

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
	xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<!--
	Example Call
	
	<xsl:call-template name="substring-count">
		<xsl:with-param name="haystack" select="'the quick brown fox jumps over the lazy dog'" />
		<xsl:with-param name="needle" select="'the'" />
	</xsl:call-template>

	Will return "2".
-->

<xsl:template name="substring-count">
	<xsl:param name="haystack"/>
	<xsl:param name="needle"/>
	
	<xsl:choose>
		<xsl:when test="contains($haystack, $needle) and $haystack and $needle">
			<xsl:variable name="count">
				<xsl:call-template name="substring-count">
					<xsl:with-param name="haystack" select="substring-after($haystack, $needle)"/>
					<xsl:with-param name="needle" select="$needle"/>
				</xsl:call-template>
			</xsl:variable>
			<xsl:value-of select="$count + 1"/>
		</xsl:when>
		<xsl:otherwise>0</xsl:otherwise>
	</xsl:choose>
</xsl:template>

</xsl:stylesheet>