class IntersectionProofNode extends ProofNode
{
    private SolutionListener watcher = new IntersectionMonitor();
    private int numOfParts;

    IntersectionProofNode(Intersection re) { 
        super(re); 
        numOfParts = re.numOfParts();
    }

    void backwardProcess() {
        super.backwardProcess();
        Iterator it = (Intersection)roleExp.getParts();
        while (it.hasNext()) {
            EntityExpression re = (EntityExpression)it.next();
            ProofNode node = addBackwardNode(firstRole);
            node.backwardMgr.addListener(watcher);
        }
    }

    class IntersectionMonitor implements SolutionListener 
    {
        // Maps a solution to a counter, no source is needed
        private HashMap  solutions;

        public void solutionAdded(ProofNode s, ProofSolution r) {
            debugInfo("Solution added: "+roleExp+"; "+s.roleExp+"; "+r);
            if (! solutions.containsKey(r)) {   // first piece
                solutions.put(r, new Integer(1));  
            } else { 
                int n = ((Integer)solutions.get(r)).intValue();
                n ++;
                solutions.put(r, new Integer(n));
                if (n == numOfParts) {  // all pieces are found
                    backwardMgr.solutionAdded(IntersectionProofNode.this, r);
                }
            }
        }
    }

    /* forwardProcess has nothing special
    void forwardProcess() {
        super.forwardProcess();
        
    } */
} // End of class IntersectionProofNode