Re: [xsl] How to compare two QName values in an XML Schema?

[Michael Kay <mike@xxxxxxxxxxxx>]

On 08/04/2011 17:00, Costello, Roger L. wrote:
> Hi Folks,
>
> Below is an XML Schema, containing two simpleTypes. The second one references the first.
>
> I want an XPath expression that compares the second simpleType's reference to the name of the first simpleType:
>
>
>      /xs:schema/xs:simpleType[1]/@name
>        eq
>      /xs:schema/xs:simpleType[2]/xs:restriction/@base
>
>
> That returns False. I want it to return True.

The @base attribute is defined as an xs:QName, but @name is not. You're 
going to have to tell it to build a QName by combining the local name in 
@name with the namespace URI in ../@targetNamespace. With a schema-aware 
XSLT processor, the best you can achieve is

/xs:schema/xs:simpleType[1]/QName(../@targetNamespace, @name)
  eq
/xs:schema/xs:simpleType[2]/xs:restriction/@base

However, running schema-aware code using the schema-for-schemas can be a little mindblowing (and processor-blowing)

Michael Kay
Saxonica

> I figured the reason it's returning False is because it is comparing the string "elev:BostonAreaSurfaceElevation" against the string "EarthSurfaceElevation". Yes?
>
> I want it to do a comparison of QNames, not strings. So I type-cast the values:
>
>
>      xs:QName(/xs:schema/xs:simpleType[1]/@name)
>         eq
>      xs:QName(/xs:schema/xs:simpleType[2]/xs:restriction/@base)
>
>
> But that gave me this error:
>
>     Casting from xs:unTypedAtomic to xs:QName can never succeed.
>
> Why?
>
> What's the correct way to do the comparison?
>
> ---------------------------------------------------------
> <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema";
>              targetNamespace="http://www.elevation.org";
>              xmlns:elev="http://www.elevation.org";
>              elementFormDefault="qualified">
>
>      <xsd:simpleType name= "EarthSurfaceElevation">
>          <xsd:restriction base="xsd:integer">
>              <xsd:minInclusive value="-1290"/>
>              <xsd:maxInclusive value="29035"/>
>          </xsd:restriction>
>      </xsd:simpleType>
>
>      <xsd:simpleType name= "BostonAreaSurfaceElevation">
>          <xsd:restriction base="elev:EarthSurfaceElevation">
>              <xsd:minInclusive value="0"/>
>              <xsd:maxInclusive value="120"/>
>          </xsd:restriction>
>      </xsd:simpleType>
>
> </xsd:schema>
> ---------------------------------------------------------
>
> /Roger