Highest sum of values per group in XSL

There is probably a very easy solution for this problem. I could easily do this in C#-LINQ. Unfortunately, I'm not so experienced with XPath and XSL.

I have an input XML file that contains the following structure:

<group>
    <val>1</val>
    <val>3</val>
    <val>1</val>
</group>
<group>
    <val>3</val>
    <val>2</val>
    <val>2</val>
</group>

Now in my XSL transform I want to define 1 variable "highestsum", which contains the highest sum of 'values'. So for the example, it would return 7, the sum of all values i开发者_如何转开发n the second group.

After some searching, this is the closest solution I found:

http://w3schools.invisionzone.com/index.php?showtopic=24265

But I have a feeling that there's a better way than using sorting in a template to achieve this result. Any takers?

I. A good XSLT 1.0 solution (brief, efficient and understandable):

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output method="text"/>

 <xsl:template match="/*">
   <xsl:for-each select="group">
     <xsl:sort select="sum(val)" data-type="number"
      order="descending"/>

     <xsl:if test="position()=1">
       <xsl:value-of select="sum(val)"/>
     </xsl:if>
   </xsl:for-each>
 </xsl:template>
</xsl:stylesheet>

when this transformation is applied on the following XML document:

<t>
    <group>
        <val>1</val>
        <val>3</val>
        <val>1</val>
    </group>
    <group>
        <val>3</val>
        <val>2</val>
        <val>2</val>
    </group>
</t>

the wanted, correct result is produced:

7

To get the desired variable definition, simply put the <xsl:for-each> instruvtion from the above code in the body of the variable.

II. An even better XSLT 2.0 (and actually XPath 2.0 one-liner) solution:

<xsl:stylesheet version="2.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output method="text"/>

 <xsl:template match="/*">
   <xsl:sequence select="max(group/sum(val))"/>
 </xsl:template>
</xsl:stylesheet>

when this transformation is applied on the same XML document, the same correct answer is produced:

7

And the wanted variable definition is simply:

  <xsl:variable name="vHighestSum" 
       select="max(group/sum(val))"/>

Finally, the same Xpath expression can be used in XQuery to define the required variable:

let $vHighestSum := max(/*/group/sum(val))