Re: [xml] Namespace Handling

[Balint Joo <bj ph ed ac uk>]

Hello,

>   I find hard to accept it as right. You can define whatever semantic
> you want for the namespace binding since there is none coming from the
> spec but prefix "a" may be associated to 10 different namespaces in the
> document, picking the fist one in document order doesn't sound right at
> all... 

I suspected this. No doubt funnies would have occurred eventually with
sufficiently complex xml documents.

> > This seems to me a great waste of time. 
>  Yes this sounds like a terrible waste.

Glad we agree :)

>   Simply walk the current node and its ancestors, the cost will be linear
> to the depth of the tree, not it size !
>   There is already a call doing this exported from the tree module
> /**
>  * xmlGetNsList:
>  * @doc:  the document
>  * @node:  the current node
>  *
>  * Search all the namespace applying to a given element.
>  * Returns an NULL terminated array of all the #xmlNsPtr found
>  *         that need to be freed by the caller or NULL if no
>  *         namespace if defined
>  */
> xmlNsPtr *
> xmlGetNsList(xmlDocPtr doc ATTRIBUTE_UNUSED, xmlNodePtr node);
>
> Daniel


I saw this function and wondered what it did. Let me see if I have this
straight:

When I parse a document my 'current' node is the 'root' node. I then

void newSnarfNamespaces(xmlDocPtr doc, xmlXPathContextPtr context_ptr)
{
        xmlNsPtr *ns_ptr_array;
        xmlNsPtr *shadow;
        xmlNodePtr root;
        int i;

        root=xmlDocGetRootElement(doc);

        // Get top level namespaces
        ns_ptr_array = xmlGetNsList(doc,root);
        
        // Walk list and register xpath
        shadow = ns_ptr_array;
        while( shadow != NULL ) {
            xmlXPathRegisterNs(context_ptr, (*shadow)->prefix, (*shadow)->href);
            shadow++; // Next
        }
        
        // free the list returned by xmlGetNsList()
        if( ns_ptr_array != NULL ) {
          xmlFreeNsList(*ns_ptr_array);
        }
        
}
        
Then I can do queries from there with namespaces
(eg //bj:gnus )?

I am not sure how any other node apart from the root node can become current.
I suppose when I do an XPath query from the root, and a single element is
returned in the node list, I can make that the 'current' node and I can search
back.

Alternatively, I can try to get to the last element of the whole tree with
repeated calls of getLastChild, and when I reach the bottom do the getNsList?
(This sounds more like the searching of the depth of the tree you mentioned)

parent=xmlDocGetRootElemet(doc);
do {
        // get last child
        last = xmlGetLastChild(parent);


        // Can go further
        if( last != NULL ) {
          // next level
          parent = last;
        }

} while( last != NULL );

// Correct for overshoot
last = parent;


This sounds wrong too somehow.

Sorry to be such a dummy. This is really the last hurdle for me and
would like to get it done :)

All the best,
        Baliint

--
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Dr Balint Joo                         Post Doctoral Research Fellow
School of Physics
University of Edinburgh
Mayfield Road, Edinburgh EH9 3JZ
Scotland UK
Tel: 0131 650 6469 (from UK) +44-131-650-6469 (from outwith UK)
Fax: 0131 650 5902 (from UK) +44-131-650-5902 (from outwith UK)
email: bj ph ed ac uk           bj phys columbia edu
WWW  : http://www.ph.ed.ac.uk/~bj
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