[xquery-talk] Q: computed element and namespace

Fri Jan 31 01:41:53 PST 2014

Thanks William!
That does not return what was requested, but changing "pre" to "urn:u" two
times does:
http://try.zorba.io/queries/xquery/BwMzU0SPVdY9X7f5DO42g15Gt94%3D

Mit besten Gruessen / Best wishes,

Hermann Stamm-Wilbrandt
Level 3 support for XML Compiler team and Fixpack team lead
WebSphere DataPower SOA Appliances
https://www.ibm.com/developerworks/mydeveloperworks/blogs/HermannSW/
https://twitter.com/HermannSW/
http://stamm-wilbrandt.de/GraphvizFiddle/
----------------------------------------------------------------------
IBM Deutschland Research & Development GmbH
Vorsitzende des Aufsichtsrats: Martina Koederitz
Geschaeftsfuehrung: Dirk Wittkopp
Sitz der Gesellschaft: Boeblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294

  From:       William Candillon <wcandillon at gmail.com>                                                                                          

  To:         Michael Kay <mike at saxonica.com>,                                                                                                  

  Cc:         Hermann Stamm-Wilbrandt/Germany/IBM at IBMDE, "talk at x-query.com Talk" <talk at x-query.com>                                             

  Date:       01/31/2014 10:17 AM                                                                                                               

  Subject:    Re: [xquery-talk] Q: computed element and namespace                                                                               

In XQuery 3.0 you could write the following:
element {"a"}{
  (
    namespace pre { "urn:u" },
    element {fn:QName("pre", "pre:b")}{},
    element {fn:QName("pre", "pre:c")}{}
  )
}
http://try.zorba.io/queries/xquery/OEkkPFKllu7moQ5l6eCBTQ1fiBY%3D

On Fri, Jan 31, 2014 at 9:51 AM, Michael Kay <mike at saxonica.com> wrote:
>
> On 31 Jan 2014, at 08:12, Hermann Stamm-Wilbrandt <STAMMW at de.ibm.com>
wrote:
>
>>
>> From (1):
>> In XPath Version 2.0, the namespace axis is deprecated and need not be
>> supported by a host language. A host language that does not support the
>> namespace axis need not represent namespace bindings in the form of
nodes.
>>
>> XQuery (eg. Zorba or DataPower) does not support the namespace axis.
>>
>>
>> <a><pre:b xmlns:pre="urn:u"/><pre:c xmlns:pre="urn:u"/></a>
>>
>> can be created by computed element constructors (2) by this:
>>
>> element {"a"}{
>>  (
>>    element {fn:QName("urn:u", "pre:b")}{},
>>    element {fn:QName("urn:u", "pre:c")}{}
>>  )
>> }
>>
>> Is it true, that "equivalent" (not sure whether right term) XML
>> <a xmlns:pre="urn:u"><pre:b/><pre:c/></a>
>>
>> cannot be created by computed element constructors in XQuery?
>
> If we're talking about XQuery 1.0, then yes, I believe that there is no
way you can create an element with a namespace that is (a) unused on that
element, and (b) not known statically.
>
> (I might be wrong; I seem to recall David Carlisle coming up with a
devious workaround, but it was so devious I don't recall how it works).
>
> Query 3.0 introduces dynamic namespace node constructors to solve this
problem. This leaves the language in the rather absurd situation that there
is a construct to create namespace nodes, but no construct to retrieve
them.
>
> The XQuery WG was very reluctant to support the namespace axis because
many vendors claimed that it was impossible to support it efficiently. Some
of those vendors, when told to look at open source implementations like xt
and Saxon that had efficient implementations, said that their company
policy did not allow them to read open source code. Shame.
>
> Michael Kay
> Saxonica
>
>>
>>
>> It can be created by XSLT 1.0+EXSLT stylesheet:
>>
>> $ java -jar ~/Desktop/saxon6-5-5/saxon.jar dummy.xml compel.xsl ; echo
>> <a xmlns:pre="urn:u"><pre:b/><pre:c/></a>
>> $
>> $ cat compel.xsl
>> <xsl:stylesheet version="1.0"
>>  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>>  xmlns:exslt = "http://exslt.org/common"
>>>
>>  <xsl:output omit-xml-declaration="yes" />
>>
>>  <xsl:template match="/">
>>    <xsl:variable name="tmp">
>>      <xsl:element name="a">
>>        <xsl:attribute name="pre:ʎɯɯnp" xmlns:pre="urn:u"/>
>>        <xsl:element name="pre:b" xmlns:pre="urn:u"/>
>>        <xsl:element name="pre:c" xmlns:pre="urn:u"/>
>>      </xsl:element>
>>    </xsl:variable>
>>
>>    <xsl:apply-templates select="exslt:node-set($tmp)/*"/>
>>  </xsl:template>
>>
>>  <xsl:template match="*">
>>    <xsl:copy>
>>      <xsl:copy-of select="namespace::*|attribute::*[local-name
>> ()!='ʎɯɯnp']"/>
>>      <xsl:apply-templates select="*"/>
>>    </xsl:copy>
>>  </xsl:template>
>>
>> </xsl:stylesheet>
>> $
>>
>>
>> (1) http://www.w3.org/TR/xpath20/#dt-in-scope-namespaces
>> (2) http://www.w3.org/TR/xquery/#id-computedElements
>>
>> Mit besten Gruessen / Best wishes,
>>
>> Hermann Stamm-Wilbrandt
>> Level 3 support for XML Compiler team and Fixpack team lead
>> WebSphere DataPower SOA Appliances
>> https://www.ibm.com/developerworks/mydeveloperworks/blogs/HermannSW/
>> https://twitter.com/HermannSW/
>> http://stamm-wilbrandt.de/GraphvizFiddle/
>> ----------------------------------------------------------------------
>> IBM Deutschland Research & Development GmbH
>> Vorsitzende des Aufsichtsrats: Martina Koederitz
>> Geschaeftsfuehrung: Dirk Wittkopp
>> Sitz der Gesellschaft: Boeblingen
>> Registergericht: Amtsgericht Stuttgart, HRB 243294
>>
>> _______________________________________________
>> talk at x-query.com
>> http://x-query.com/mailman/listinfo/talk
>
>
> _______________________________________________
> talk at x-query.com
> http://x-query.com/mailman/listinfo/talk