XSLT Trim String to Word Boundary with Ellipsis

I found pieces of this and modified it for my use. Include these two templates and call summary-text.

  <xsl:template name="summary-text">

    <xsl:param name="in" />

    <xsl:param name="allowable-length" select="50" />

    <xsl:if test="string-length($in) <= $allowable-length">

      <xsl:value-of select="$in" />

    xsl:if>

    <xsl:if test="string-length($in) > $allowable-length">

      <xsl:call-template name="trim-last-word">

        <xsl:with-param name="in" select="substring($in, 1, $allowable-length)" />

      xsl:call-template>

      <xsl:text>...xsl:text>

    xsl:if>

  xsl:template>

  <xsl:template name="trim-last-word">

    <xsl:param name="in" />

    <xsl:choose>

      <xsl:when test="substring($in, string-length($in), 1)=' '">

        <xsl:value-of select="$in" />

      xsl:when>

      <xsl:otherwise>

        <xsl:call-template name="trim-last-word">

          <xsl:with-param name="in" select="substring($in, 1, string-length($in)-1)" />

        xsl:call-template>

      xsl:otherwise>

    xsl:choose>

  xsl:template>

It will take a string like this:

Now is the time for all good people to come to the aid of their country.

And transform it to this:

Now is the time for all good people to come to the...