Can I store sums of values in xsl?

Question

Say I have an Xml fragment that I am walking through with XSL:

<Columns>
   <Column width="100">
   <Column width="50">
   <Column width="75">
   <Column width="33">
</Columns>

Basically what I want to do is, as I am walking through each node, I need to store a sum of the previous 'width' attributes to be used for the current Column node. For example, when I reach the last Column node (with width 33), I would like to have access to the sum of the all the previous widths in a variable of some kind (100+50+75). I know that values of variables cannot be changed once set in XSL, so I'm wondering if there is some way using template params or something to do this. Thanks in advance!

Answer 1

Essentially you take advantage of template recursion and limit the set being passed to the next sibling only. Starting with the first item then you can continually pass in updated values to the next template call.

<xsl:template match="/">
    <xsl:apply-templates select="Columns/Column[1]" />
</xsl:template>

<xsl:template match="Column">
    <xsl:param name="runningtotal" select="0"/>
    [<xsl:value-of select="@width"/>:<xsl:value-of select="$runningtotal+@width"/>]
    <xsl:apply-templates select="following-sibling::Column[1]" >
     <xsl:with-param name="runningtotal" select="$runningtotal+@width"/>
    </xsl:apply-templates>
</xsl:template>