lnamest and nameend change into colspan

I want to change the namest and nameend attribute value into the the colspan attribute value

XML Input:

<row>
    <entry nameend="col2" namest="col1">Claims</entry>
</row>

XSL I'm having:

<xsl:template match="row">
    <tr>
      <xsl:apply-templates/>
    </tr>
  </xsl:template>
  
  <xsl:template match="entry">
    <td>
      <xsl:apply-templates/>
    </td>
  </xsl:template>

Expected Output is:

 <tr>
    <td colspan="2">Claims</td>
</tr>

If the namest="1" and nameend="3", the colspan value would be 3. It have to depend on namest and nameend values. It have to calculate the numbers from namest and nameend.

Solution

It is hard to come up with an algorithm based on a single example, with no rules given. The following should work for your input above:

<xsl:template match="entry">
    <xsl:variable name="start" select="substring-after(@namest, 'col')" />
    <xsl:variable name="end" select="substring-after(@nameend, 'col')" />
    <td colspan="{$end - $start + 1}">
        <xsl:apply-templates/>
    </td>
</xsl:template>

This is assuming you are using XSLT 1.0. If you are using an XSLT 2.0 processor and your stylesheet is tagged as version="2.0" then you need to do:

<xsl:template match="entry">
    <xsl:variable name="start" select="number(substring-after(@namest, 'col'))" />
    <xsl:variable name="end" select="number(substring-after(@nameend, 'col'))" />
    <td colspan="{$end - $start + 1}">
        <xsl:apply-templates/>
    </td>
</xsl:template>