Re: [xml] XPath empty default namespaces (bug?)

[Daniel Veillard <veillard redhat com>]

On Wed, Oct 31, 2001 at 11:46:25AM -0800, Alex Dron wrote:
> Hi,
> I'm working on implementation of Canonical XML
> (http://www.w3.org/TR/2001/REC-xml-c14n-20010315) and use this library.


  Interesting,

> The major problem I bump into is incorrect (IMHO) XPath behavior with empty
> default namespaces.
> Consider test 3.7 of the URL above, the next XPath expression (evaluated
> with namespace declaration xmlns:ietf="http://www.ietf.org";):
> ----------------------------------------------
> (//. | //@* | //namespace::*)
> [ self::ietf:e1 or (parent::ietf:e1 and not(self::text() or self::e2))
>   or
>   count(id("E3")|ancestor-or-self::node()) =
> count(ancestor-or-self::node())]
> ----------------------------------------------
> against XML:
> ----------------------------------------------
> <!DOCTYPE doc [
> <!ATTLIST e2 xml:space (default|preserve) 'preserve'>
> <!ATTLIST e3 id ID #IMPLIED>
> ]>
> <doc xmlns="http://www.ietf.org"; xmlns:w3c="http://www.w3.org";>
>    <e1>
>       <e2 xmlns="">
>          <e3 id="E3"/>
>       </e2>
>    </e1>
> </doc>
> ----------------------------------------------
> Should not return <e2> node, but it does! Xerces Xpath works fine with this

  Hum, it could be either:
    - that the e2 node still inherits the default namespace error
    - an XPath error

 1/ is simple to fix
 2/ would be a major pain

  I hope it's 1/ I will loook at it.

> example... It adds default attribute, too - libxml doesn't do it by itself,
> but I can live with it.

  Do the following before any call to the parser:
    xmlLoadExtDtdDefaultValue = XML_DETECT_IDS | XML_COMPLETE_ATTRS;

 it will load the DTD and should add defaulted attributes directly in the
tree. the XSLT code does this to follow the XPath spec closely.

> Libxml works correctly if I declare additional namespace (i.e
> ns="http://somewhere";) using xmlXPathRegisterNs and rewrite XPath expression
> as:
> ----------------------------------------------
> (//. | //@* | //namespace::*)
> [ self::ietf:e1 or (parent::ietf:e1 and not(self::text() or self::ns:e2))
>   or
>   count(id("E3")|ancestor-or-self::node()) =
> count(ancestor-or-self::node())]
> ----------------------------------------------

  Okay so it's probably an error building the tree

> But it's not workaround for me, because I cannot modify users expressions...
> I'm using the latest version of the library. I understand that very few
> people will pay attention to the such trifle, but maybe somebody will point
> me, whether I could fix it on my own (change sources?) and how feasible it
> is...

  I will try to fix it,

Daniel

-- 
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