Re: Issue: duplicate attributes

[Kohsuke KAWAGUCHI <kohsuke.kawaguchi@eng.sun.com>]

> the intersection of the set of attribute names possible in p1 and the set of
> attribute names possible in p2 must be empty.  Is it always possible to
> determine whether the intersection of two name classes is empty?  (I think
> so, but I would need to do some work to be sure.)

I don't think we can determine whether the intersection of two classes
is empty or not in some cases especially with the presence of <difference>.

Other primitives can be solved inductively. but not <difference>.

boolean isEmpty( NameClass nc1, NameClass nc2 )
{
  if( nc1 is SimpleNameClass )
    return nc2.accept(nc1.namespace, nc1.local);
  ...
  
  if( nc1 is ChoiceNameClass(c1,c2) )
    return isEmpty(c1,nc2) && isEmpty(c2,nc2);
  
  if( nc1 is ConcurNameClass(c1,c2) )
    return isEmpty(c1,nc2) || isEmpty(c2,nc2);
  
  if( nc1 is DifferenceNameClass(c1,c2) )
    ????
}

--
Kohsuke KAWAGUCHI                          +1 650 786 0721
Sun Microsystems                   kohsuke.kawaguchi@eng.sun.com