[xsl] number collapsing

[Bruce D'Arcus <bdarcus@xxxxxxxxxxxxx>]

Awhile back I got help from the list working on a function to collapse 
page numbers (e.g. 455-456 becomes 455-56).*

I now have a related issue, which I'm now sure how to tackle:

In numeric style citations, the in-text markers look like [1].  If one 
has multiple references, then, you'd get [1, 2, 3].

So how can I get [1-3] or (in some cases)  [1-3, 5]?

Bruce

* here it is:

  <xsl:function name="bib:number-condense">
    <xsl:param name="begin"/>
    <xsl:param name="end"/>
    <xsl:choose>
      <xsl:when test="$begin castable as xs:integer">
        <xsl:variable name="begin" select="$begin" as="xs:integer"/>
        <xsl:choose>
          <xsl:when test="$begin gt 100 and $begin mod 100 and $begin 
idiv 100 eq $end idiv 100">
            <xsl:value-of select="$end mod 100"/>
          </xsl:when>
          <xsl:otherwise>
            <xsl:value-of select="$end"/>
          </xsl:otherwise>
        </xsl:choose>
      </xsl:when>
      <xsl:otherwise>
        <xsl:value-of select="$end"/>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:function>