Re: [xml] Possible Problem|Bug in the XPath Subsystem

[Daniel Veillard <veillard redhat com>]

On Tue, Mar 18, 2003 at 01:31:14PM +0100, Christian Glahn wrote:
> Hello,
>
> While preparing XML::LibXML for a release I added some tests for XPath 
> statements. I stumbled over some strange issues with XPath statements.
> It looks pretty much like a inconsisty in the XPath engine to me.
>
> I give some example documents. All statements are executed on the
> document node or the document element node.
>
>      <C:A xmlns:C="D"><C:A><C:B/></C:A><C:A><C:B/></C:A></C:A>
>
> delivers with the following XPath statement the expected results:
>
>      descendant-or-self::node()/C:A
>
> all three nodes are returned as expected if run on the root element.
>
> This is allright if the following documents and statements won't fail, 
> but they do. :(
>
> Case a) with default namespaces
>
>     <A xmlns="D"><A><B/></A><A><B/></A></A>
>
> and the stantement 
>
>    descendant-or-self::node()/A
>
> doesn't return anything

  That's normal, compliance with the spec ! "A" matches only
node of name A in no namespace, check the spec !

> Case b) no namespace but a 'prefix'
>
>     <C:A><C:A><C:B/></C:A><C:A><C:B/></C:A></C:A>
>
> and the statement 
>
>     descendant-or-self::node()/C:A
>
> returns no nodes

  XPath requires the document to be compliant with the namespace REC
and that's not the case, 

> funny enough the statement 
>
>     descendant-or-self::*[local-name()='A']
>
> returns three nodes on the same document, although there is no localname 'A'
> in the first place. and the statement
>
>     descendant-or-self::*[local-name()='C:A']
>
> again returns nothing, although I expect no namespace prefix present.
>
> Because of this inconsisty I am a bit confused ... is it just me or is it a
> bug?

  You're operating outside of the scope of the specification.
Libxml2 will emit a warning on your document, it's well formed w.r.t. 
the XML REC 1.0 but not compliant to the Namespace in XML REC.

Daniel

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