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[Bug 11073] New: Type errors during XPath evaluation

From: <bugzilla@jessica.w3.org>
Date: Sat, 16 Oct 2010 18:24:47 +0000
To: www-xml-schema-comments@w3.org
Message-ID: <bug-11073-703@http.www.w3.org/Bugs/Public/>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=11073

           Summary: Type errors during XPath evaluation
           Product: XML Schema
           Version: 1.1 only
          Platform: PC
        OS/Version: Windows NT
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Structures: XSD Part 1
        AssignedTo: David_E3@VERIFONE.com
        ReportedBy: mike@saxonica.com
         QAContact: www-xml-schema-comments@w3.org
                CC: cmsmcq@blackmesatech.com


In section 3.12.4 (CTA) it is stated that "If a dynamic error or a type error
is raised during evaluation, then the {test} is treated as if it had evaluated
(without error) to false."

This is then glossed in a Note: "Dynamic errors and type errors in the
evaluation of {test} expressions cause neither the schema nor the document
instance to be invalid."

The reader could be forgiven for missing the significance of the phrase "during
evaluation" | "in the evaluation" in these sentences. Neither is intended to
apply to type errors that are detected statically. XPath processors are at
liberty to detect type errors statically, and such errors should be handled in
the same way as syntax errors in the XPath expression - that is, a violation of
the constraints on schema documents. It would be easy enough to add to the note
the sentence: "However, if type errors are detected statically by the XPath
processor, the effect is the same as for other static errors in the XPath
expression."

This then raises the question that 3.12.6 states:

"The {expression} property of the XPath Expression is a valid XPath expression,
as defined in [XPath 2.0]."

However, XPath 2.0 does not define the term "valid XPath expression". I think
that what is intended is "an XPath expression containing no static errors".

The text for assertions in 3.13.6.2 makes the same mistake in referring to
"valid XPath expressions."

For evaluation of assertions, I can't find any text equivalent to that in CTA
that says dynamic errors cause the assertion to be treated as false. Perhaps I
missed it.

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Received on Saturday, 16 October 2010 18:24:49 GMT

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