Right, that's one of the divergences between the
XPath model and libxml internal representation that
I don't know how to handle cleanly. Namespace nodes
are stored as children of the element where they are
defined and identified by reference on nodes using them.
namespace::* lists all the namespaces in scope but
the information of where the nodes where collected
(and hence the parent) is not kept. It's an open issue
of libxslt implementation ... So far this is the first time
anybody discovered it. Did you hit it by running a testsuite
or due to a real application ?

Daniel

I have hit this bug in a real application: I like to include in an
XSLT output tree the pseudo-listing of a XML document (by pseudo
listing I mean that since the parser is "eating" information such as
entity declarations and references I won't get the real source, but
I'd like to get as close as possible).

When I match an element in this "source listing mode", I need to
generate the declaration of the namespaces that are different than
those found on the parent node and was doing so inside a	xsl-foreach loop
on the namespaces nodes of the current element:

<xsl:for-each select="namespace::*">
 <xsl:if
test="not(parent::*/parent::*/namespace::*[name()=name(current()) and
.=current()])">
  <xsl:text> xmlns:</xsl:text>
  <xsl:value-of select="name()"/>
  <xsl:text>="</xsl:text>
  <xsl:value-of select="."/>
  <xsl:text>"</xsl:text>
 </xsl:if>
</xsl:for-each>
 
I don't think the test can be moved in the for-each select attribute
without still needing to reference the namespace node's parent since
you need a double test to check that a namespace is identical (its
string value and its name must be identical).

Hope this helps.

Eric

Just to add that, in my specific case, there is a workaround using a
variable to store the parent nodeset before descending to the
namespace nodes:

<xsl:variable name="parent" select=".."/> 
<xsl:for-each select="namespace::*">
 <xsl:if test="not($parent/namespace::*[name()=name(current()) and
.=current()])">
  <xsl:text> xmlns:</xsl:text>
  <xsl:value-of select="name()"/>
  <xsl:text>="</xsl:text>
  <xsl:value-of select="."/>
  <xsl:text>"</xsl:text>
 </xsl:if>
</xsl:for-each>

The bug is thus non blocking, however these differences between XSLT
processors are a threat to the portability of style sheets.

Thanks, Eric.

Yep, basically that's one of the easiest way to try to
avoid the problem while preserving libxml2 binary compatibility,
adding the parent(s) information at the nodeset level, unfortunately
this break very very easilly if done too simply. I'm still waiting
to find a better way to handle this, I may have to allocate an extra
structure associated to the node-set hosting the list of parents
for the namespace nodes in the set. A real pain.
The notion of parent of a namespace node in the XPath model doesn't
make that much sense to me, for example what would be the parent
for the node representing "xml" ? That part is weak IMHO.

  thanks a lot for the feedback, I will try to get this fixed.

Daniel

Finally fixed that problem. Basically each time a namespace node
is added to a node set I actually make a copy of the source
node and keep the parent on the 'next' field of that node. It slows
dealloaction of nodesets a bit, but at least that last serious
conformance problem is now fixed !

paphio:~/XSLT/tests/general -> xsltproc bug-63.xsl ../docs/bug-63.xml 
<?xml version="1.0"?>
<namespace><name>xsl</name><uri>http://www.w3.org/1999/XSL/Transform</uri><parent><xsl:stylesheet
xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:template match="*">
<xsl:for-each select="namespace::*">
<namespace>
<name><xsl:value-of select="name()"/></name>
<uri><xsl:value-of select="."/></uri>
<parent><xsl:copy-of select=".."/></parent>
</namespace>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet></parent></namespace><namespace><name>xml</name><uri>http://www.w3.org/XML/1998/namespace</uri><parent><xsl:stylesheet
xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:template match="*">
<xsl:for-each select="namespace::*">
<namespace>
<name><xsl:value-of select="name()"/></name>
<uri><xsl:value-of select="."/></uri>
<parent><xsl:copy-of select=".."/></parent>
</namespace>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet></parent></namespace>
paphio:~/XSLT/tests/general -> 

  thanks for the report !

Daniel

Okay this has been fixed for a couple of released now,

  thanks,

Daniel