Re: [xsl] How to output the unused namespaces in the XML document?

[Michael Kay <mike@xxxxxxxxxxxx>]

 It isn't possible to know whether a namespace is unused. I think what 
you mean is "not used in any element or attribute name".

The simple answer to that in XPath 2.0 is 
distinct-values(//namespace::*[not(. = //*/namespace-uri() or . = 
//@*/namespace-uri())]).

However, your code is testing something different. Given this source 
document

<?xml version="1.0"?>
<N1:NumberList>
        <Number>23</Number>
        <Number>41</Number>
        <Number xmlns:N3="http://www.example3.org";>70</Number>
        <N3:Number xmlns:N3="http://www.example3.org";>103</Number>
        <Number>99</Number>
        <Number>6</Number>
</N1:NumberList>

You will report http://www.example3.org as unused because there is a 
declaration of this namespace that is not used in any ancestor or 
descendant of the element where it is declared; my code considers it as 
used because there is an element where it is used. As usual, it all 
comes down to careful specification of your problem.

Michael Kay
Saxonica
> Hi Folks,
>
> Consider this XML document:
>
> <?xml version="1.0"?>
> <N1:NumberList xmlns:N1="http://www.example1.org";
>                 xmlns:N2="http://www.example2.org";>
>          <Number>23</Number>
>          <Number>41</Number>
>          <Number xmlns:N3="http://www.example3.org";>70</Number>
>          <Number>103</Number>
>          <Number>99</Number>
>          <Number>6</Number>
> </N1:NumberList>
>
> Notice that there are three (3) namespaces, but two of them are unused:
>
>      http://www.example2.org
>
>      http://www.example3.org
>
> I want an XSLT transform that will output all the unused namespaces in the input XML document.
>
> Here's the solution I came up with:
>
>
>      <xsl:template match="*">
>          <xsl:variable name="elem" select="." />
>          <xsl:for-each select="namespace::*[. != 'http://www.w3.org/XML/1998/namespace']">
>              <xsl:variable name="ns" select="." />
>              <xsl:if test="not($elem/ancestor::*[namespace::* = $ns])">
>                  <xsl:if test="not($elem/descendant-or-self::*[namespace-uri() = $ns])">
>                      This namespace is unused:<xsl:value-of select="$ns" />
>                  </xsl:if>
>              </xsl:if>
>          </xsl:for-each>
>          <xsl:apply-templates select="*" />
>      </xsl:template>
>
>
> Is there a better solution? (I am using XSLT 1.0)
>
> /Roger