[xsl] key() question?

[Steven Noels <stevenn at outerthought dot org>]

Hi all,

I'm trying to wrap my brains across a problem which I assume I must be 
solving using nasty key() tricks.

Here's how my input file looks like:

  <contentModel ename="document">
    <group>
      <element name="header"/>
      <separator type=","/>
      <element name="body"/>
      <separator type=","/>
      <element name="footer"/>
      <occurrence type="?"/>
    </group>
  </contentModel>
  <attlist ename="document">
    <attributeDecl aname="id" ename="document" atype="ID"/>
    <attributeDecl aname="xml:lang" ename="document" atype="NMTOKEN"/>
  </attlist>
  <contentModel ename="header">
    <group>
      <element name="title"/>
      <separator type=","/>
      <element name="subtitle"/>
      <occurrence type="?"/>
      <separator type=","/>
      <element name="version"/>
      <occurrence type="?"/>
      <separator type=","/>
      <element name="type"/>
      <occurrence type="?"/>
      <separator type=","/>
      <element name="authors"/>
      <occurrence type="?"/>
      <separator type=","/>
      <element name="notice"/>
      <occurrence type="*"/>
      <separator type=","/>
      <element name="abstract"/>
      <occurrence type="?"/>
    </group>
  </contentModel>
  <attlist ename="header">
    <attributeDecl aname="id" ename="header" atype="ID"/>
    <attributeDecl aname="xml:lang" ename="header" atype="NMTOKEN"/>
  </attlist>

and much more like this, so in essence I have plenty of <contentModel> 
and <attlist> elements which contain content model defitions composed of 
<element>s, <group>s and the like. Think DTDs but in an XML syntax.

I have some keys declared for easy access to the attributes declared for 
a specific element, and to retrieve the contentModels in which an 
element is referred to:

<xsl:key name="attlistbyname" match="/dtd/attlist" use="@ename"/>
<xsl:key name="contentmodelbychildren" match="//contentModel" 
use="descendant::element/@name"/>

The problem with DTDs without an accompagnying instance is that you are 
not able to devise which element is the root element. As a rule of thumb 
in my situation, I define root elements as <contentModel> elements which 
have no <element> counterpart, i.e. the 'document' contentModel in this 
case: you find a <contentModel ename="document"> without an <element 
name="document"/> that refers to it inside some other <contentModel>.

My question is how I can easily locate <contentModel> elements which 
don't have an <element> counterpart bearing an attribute 'name' with the 
contentModel/@ename as its value.

Anyone an idea?

</Steven>
--
Steven Noels                            http://outerthought.org/
Outerthought - Open Source, Java & XML Competence Support Center
stevenn@outerthought.org                      stevenn@apache.org


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