//	Object ring (simplified queue)
//
//	Author	Matthew Caryl
//
//  Although under copywrite to the author (Matthew Caryl) this code can be copied and modified for non-commercial
//  purposes as long as any derivatives contain this condition.

package ADT;

final public class Ring {
    Object[]    ring = null;
    int         current;

    // copy order of elements from queue into ring
    public Ring(Queue source) throws QueueEmpty {
        int s = source.size();
        int i;
        
        if (source.empty())
            throw new QueueEmpty();
        ring = new Object[s];
        try {
            for (i = 0; i < s; i++)
                ring[i] = source.requeue();
            }
        catch (QueueEmpty e) {
            }
        current = 0;
        }

    // returns the object at the front of the ring
    public Object peekqueue() {
        return ring[current];
        }

    // returns the object at the front of the ring
    // and moves onto the next object
    public Object requeue() {
        Object  o;
        
        o = ring[current];
        current++;
        if (current >= ring.length)
            current = 0;
        return o;
        }

    public boolean membership(Object o) {
        int p, q;

        p = 0;
        q = ring.length;
        while (p != q)
            if (ring[p] == o)
                q = p;
            else
                p++;
        return p != ring.length;
        }

    public int size() {
        return ring.length;
        }
    }