@Override
public Node traverse(SelectorLeaf selector) {
Node secondNode = selector.traverse(baseContext);
Set<Tally> tallies = new HashSet<Tally>();
tallies.addAll(firstNode.getTallies());
tallies.retainAll(secondNode.getTallies());
assert tallies.isEmpty() || tallies.size() == 1;
if (tallies.isEmpty()) {
Tally tally = newTally(firstNode, secondNode);
firstNode.addTally(tally);
secondNode.addTally(tally);
return tally.getNode();
} else {
return tallies.iterator().next().getNode();
}
}
@Override
public Node traverse(SelectorLeaf selector) {
return selector.traverse(this);
}