XSLT, 2nd Edition

Creating New Datatypes by Restriction

A common way to create new datatypes is to restrict the values of another datatype. We’ll look at three approaches: ranges, enumerations, and regular expressions.

For our first example, we’ll use a range to define a datatype called age based on xs:integer. We would like for the age datatype to have a value between 0 and 130. (We’re being optimistic about longevity here.) Here’s how we define a range of valid values:

<?xml version="1.0" encoding="UTF-8"?>
<!-- person1.xsd -->
<xs:schema 
  xmlns="http://www.oreilly.com/xslt"
  targetNamespace="http://www.oreilly.com/xslt"
  xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xs:element name="person">
    <xs:complexType>
      <xs:sequence>
        <xs:element ref="name"/>
        <xs:element ref="age"/>
      </xs:sequence>
      <xs:attribute name="eyeColor" type="xs:string"/>
    </xs:complexType>
  </xs:element>

  <xs:element name="name" type="xs:string"/>

  <xs:simpleType name="age-type">
    <xs:restriction base="xs:integer">
      <xs:minInclusive value="0"/>
      <xs:maxInclusive value="130"/>
    </xs:restriction>
  </xs:simpleType>

  <xs:element name="age" type="age-type"/>

</xs:schema>

We’ve defined a new datatype, age-type, and we’ve used it as the datatype for the element <age>. Here’s a valid document for this schema:

<?xml version="1.0" encoding="utf-8"?>
<!-- person1.xml --> <person xmlns="http://www.oreilly.com/xslt" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.oreilly.com/xslt person1.xsd" eyeColor="brown"> <name>Doug ...