XOM API for Processing XML with Java

[Laurent Bihanic <laurent.bihanic AT atosorigin.com>]

Elliotte Rusty Harold wrote:
> At 7:26 PM +0100 1/15/03, Laurent Bihanic wrote:
> > Hence, you can easily reach the following situation:
> > 1. call e.addNamespaceDeclaration() to redeclare the NS of an 
> > attribute: OK
> > 2. call e.getNamespaceURI(prefix): OK, youy get the NS URI
> > 3. call e.getNamespaceDeclarationCount and a loop to gather all 
> > prefixes: You won't find the namespace you've just declared.
>
> Actually, you can't reach that situation, or at least I don't think you 
> can. Curretnly, you cannot redeclare the namespace of an attribute by 
> calling e.addNamespaceDeclaration(). Did you mean something else?

Yes, you can. Here's an except (from XOM 1.0d8) of Element.declareNamespace():

        // check for conflicts with attribute prefixes
        if (!prefix.equals("")) {
            for (int i = 0; i < attributes.size(); i++) {
                Attribute a = attributes.get(i);
                if (a.getNamespacePrefix().equals(prefix)) {
                    if (a.getNamespaceURI().equals(uri)) break;
                    else {
                        throw new NamespaceException(
                         "Attribute prefix conflicts with additional 
namespace");
                    }
                }
            }
        }

        // local constraints
        checkAddNamespaceDeclaration(prefix, uri);

        namespaces.put(prefix, uri);
    }

If the prefix and URI are the same as one of the attribute namespace, the 
break statement causes the namespace to be added.

But your right, the namespace is *really* added into the namespaces table so 
you can see it in a loop using getNamespaceDeclarationCount and 
getNamespacePrefix(int).

Here's another asymmetry: Redeclaration of attribute namespace is added to the 
table while redeclaration of the element namespace is not (uses a return; 
statement instead of a break;). Was this done on purpose? If yes, you should 
add a comment to document it.

So my example still applies if, in step 1, you try to redeclare the namespace 
of the element itself.

Laurent