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[Bug 8791] New: [XPath21] Allowing intermediate XPath steps to return atomic values

From: <bugzilla@wiggum.w3.org>
Date: Thu, 21 Jan 2010 05:48:32 +0000
To: public-qt-comments@w3.org
Message-ID: <bug-8791-523@http.www.w3.org/Bugs/Public/>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=8791

           Summary: [XPath21] Allowing intermediate XPath steps to return
                    atomic values
           Product: XPath / XQuery / XSLT
           Version: Working drafts
          Platform: All
               URL: http://www.w3.org/TR/2009/WD-xpath-21-20091215/
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: XPath 2.1
        AssignedTo: jonathan.robie@redhat.com
        ReportedBy: gandhi.mukul@gmail.com
         QAContact: public-qt-comments@w3.org


Hi all,
  The following XPath (2.0) expression would raise an error, because the 2nd
step in the expression, returns an atomic value:

[1]
product/substring(name,1,30)/replace(.,' ','-')

This happens because, the XPath 2.0 language (and also the XPath 2.1 draft I
believe -- which I'm not sure; please correct me if I am wrong) only allows the
last step of an XPath expression, to return atomic values.

I think, it would be nice to allow a XPath syntax something like below:

product/substring(name,1,30)/replace($value,' ','-')

The implicit variable reference, $value would only work if the previous XPath
step is a sequence of atomic values (0-n in no's). Each call to replace
function, would get an atomic value (the first argument) from the previous
step.

If the XPath step doesn't return an atomic value (which means, it returns
node(s)), then $value will be empty sequence.

This enhancement to XPath syntax would easy writing of some of complex XPath
expressions.

For e.g, the expression [1] (which is currently, disallowed) above currently
might be accomplised like following:

product/(for $n in name return replace(substring($n,1,30),' ','-'))

Regards,
Mukul


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Received on Thursday, 21 January 2010 05:48:33 UTC

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