if ( mapping == null )
{
mapping = new IdentityHashMap<Binding, LabelToNodeMap>() ;
env.getContext().set(keyMap, mapping) ;
}
LabelToNodeMap mapper = mapping.get(binding) ;
if ( mapper == null )
{
mapper = LabelToNodeMap.createBNodeMap() ;
mapping.put(binding, mapper) ;
}
Node bnode = mapper.asNode(x.getString()) ;
return NodeValue.makeNode(bnode) ;
}