xslt coalesce function with Saxon

Question

Does anyone know of a built in function for performing a coalesce in XSLT, or will I need to write my own?

I have some xml like this:

<root>
 <Element1>
   <Territory>Worldwide</Territory>
   <Name>WorldwideName</Name>
   <Age>78</Age>
 </Element1>
 <Element1>
   <Territory>GB</Territory>
   <Name>GBName</Name>
 </Element1>
</root>

The second element1 (GB Territory) is completly optional and may or maynot occur, however when it does occur it takes precedence over the the WorldWide Territory.

So what I was after is something like the the coalesce below:

<xsl:variable name="Worldwide" select="root/Element1[./TerritoryCode ='Worldwide']"/>
<xsl:variable name="GB" select="root/Element1[./TerritoryCode ='GB']"/>

<xsl:variable name="Name" select="ext:coalesce($GB/Name, $Worldwide/Name)"/>

The id being that variable Name in the above example will contain GBName.

I know I could use the xsl:choose, but I have some places where there are 4 places it could look and the xsl:choose just becomes messy and complicated, so was hoping to find a built in function, but had no luck so far.

Thank you.

Answer 1

In XSLT 2.0 you could just create a sequence of items from your variables and then select the first one with a predicate filter:

<xsl:variable name="Name" select="($GB/Name, $Worldwide/Name)[1]"/>

The predicate filter will select the first non-null item in the sequence.

For instance, this would still produce "GBName":

<xsl:variable name="emptyVar" select="foo"/>
<xsl:variable name="Worldwide" select="root/Element1[Territory ='Worldwide']"/>
<xsl:variable name="GB" select="root/Element1[Territory ='GB']"/>

<xsl:variable name="Name" select="($emptyVar, $GB/Name, $Worldwide/Name)[1]"/>