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RE: Uniqueness operator for XPath?

• From: Adam Van Den Hoven <Adam.Hoven@b...>
• To: "'xml-dev@l...'" <xml-dev@l...>
• Date: Thu, 08 Feb 2001 12:47:17 -0800

Clark, 

> Thoughts?  I suppose you may think that this should be
> in the realm of schema, but I'm not so sure.  It is
> rather fundamental.

First of all, what you are talking about is not a uniqueness operator. If
you want your ! (bad choice since ! is typically NOT but something could be
used) to be a uniqueness operator then your path

/html/!head/!title

would mean "Give me the unique title of the unique header of the html
document element". It suggests that if head or title are not unique then
return nothing. 

Also unique with respect to what? Unique among its siblings, or over the
whole document. What is unique? The element name, the element and all its
contents, or the element and its attributes.

Also the way in which /html/head[1]/title[1] is retrieved may in fact be
optimized so that the whole nodelist is not retrieved. 

Adam

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