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At 10:14 AM +0000 3/2/02, Michael Kay wrote: >Nothing in a schema can make an XPath 1.0 expression invalid. What is >possible is that by examination of a schema you can statically determine >that a particular XPath expression will return an empty node-set. That seems to me a very dangerous thing to do. While you could determine that this is true for *valid* documents, not all documents are valid, not even all documents that reference a schema. XPath (both 1.0 and 2.0) does not require validity. A conformant XPath processor should not fail when faced with an invalid but well-formed document. I suppose it would be possible to first test validity, and then, once the document had been validated, use these optimizations. However, I'm not sure that this would actually buy you anything in the long run. -- +-----------------------+------------------------+-------------------+ | Elliotte Rusty Harold | elharo@m... | Writer/Programmer | +-----------------------+------------------------+-------------------+ | The XML Bible, 2nd Edition (Hungry Minds, 2001) | | http://www.cafeconleche.org/books/bible2/ | | http://www.amazon.com/exec/obidos/ISBN=0764547607/cafeaulaitA/ | +----------------------------------+---------------------------------+ | Read Cafe au Lait for Java News: http://www.cafeaulait.org/ | | Read Cafe con Leche for XML News: http://www.cafeconleche.org/ | +----------------------------------+---------------------------------+
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