public String next() throws StandardException {
if (initial) {
// Optimization so we don't compute the closure for the current
// role if unnecessary (when next is only called once).
initial = false;
seenSoFar.put(root, null);
return root;
} else if (graph == null) {
// We get here the second time next is called.
graph = dd.getRoleGrantGraph(tc, inverse);
List outArcs = (List) graph.get(root);
if (outArcs != null) {
currNodeIter = outArcs.iterator();
}
}
RoleGrantDescriptor result = null;
while (result == null) {
while (currNodeIter.hasNext()) {
RoleGrantDescriptor r = (RoleGrantDescriptor) currNodeIter.next();
if (seenSoFar.containsKey(inverse ? r.getRoleName() : r.getGrantee())) {
continue;
} else {
lifo.add(r);
result = r;
break;
}
}
if (result == null) {
// not more candidates located outgoing from the
// latest found node, pick another and continue
RoleGrantDescriptor newNode = null;
currNodeIter = null;
while (lifo.size() > 0 && currNodeIter == null) {
newNode = (RoleGrantDescriptor) lifo.remove(lifo.size() - 1);
// In the example (see interface doc), the
// iterator of outgoing arcs for f (grant inverse)
// would contain {e,c,d}.
List outArcs = (List) graph.get(inverse ? newNode.getRoleName() : newNode.getGrantee());
if (outArcs != null) {
currNodeIter = outArcs.iterator();
} // else: leaf node, pop next candidate, if any
}
if (currNodeIter == null) {
// candidate stack is empty, done
currNodeIter = null;
break;
}
}
}
if (result != null) {
String role = inverse ? result.getRoleName() : result.getGrantee();
seenSoFar.put(role, null);
return role;
} else {
return null;
}
}
