[xsl] Re: key() question?

[Dimitre Novatchev <dnovatchev@xxxxxxxxx>]

--- Steven Noels <stevenn at outerthought dot org> wrote:
>
> 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?
> 


Hi Steve,

To find all such contentModel, use the following XPath expression:

/dtd/contentModel[not(@ename = /dtd/contentModel/group/element/@name)]


Cheers,
Dimitre Novatchev.

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