Re: [xml-dev] XPath challenge: can you simplify this XPath expression?

["G. Ken Holman" <gkholman@CraneSoftwrights.com>]

At 2009-05-11 18:49 +0200, Philippe Poulard wrote:
>Costello, Roger L. a écrit :
>>Hi Folks,
>>I created an XPath expression and I am wondering if it can be simplified.
>>The XPath expresses this:
>>    There must be one child Title element and
>>    there must be zero or more child Author elements and
>>    there must be one child Date element and
>>    nothing else.
>>
>>Here's the XPath 2.0 expression I created:
>
>Hi,
>
>I don't know how to write it with XPath 2, but 
>wouldn't it be simpler to say: "the context has 
>the type xxx" where xxx is the type defined in a 
>schema, using schema-element() ?
>
>I'm almost sure Saxon-SA can do that... any confirmation ?

I don't think you can express Roger's constraints in W3C-Schema-speak.

In ISO/IEC 19757-2 RELAX-NG Compact Syntax it would be:

   ( Title & Author* & Date )

... which takes advantage of the interleave 
concept in RELAX-NG that is not in W3C Schema.

How would you think one would write the content 
model in W3C Schema to satisfy Roger's 
constraints?  If successful, then yes one could 
consider using the XPath schema validation 
approach, which yes Saxon-SA can do just fine.

Perhaps you can write it in W3C-Schema-speak and 
I just cannot see it and I'm missing something obvious.

. . . . . . . . . . Ken

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