// Must compile with "javac -source 1.4 SimpleSet.java"

class SimpleSetFullException extends Exception { }

public class SimpleSet {
    final int MAX_MEMBERS = 3;
    Object[] content = new Object[MAX_MEMBERS];

    public class SimpleSetIterator implements java.util.Iterator {
        private int currentPosition = 0;
        final Object[] content;
        public SimpleSetIterator(SimpleSet s) {
            content = s.content;
        }
        public boolean hasNext() {
            return currentPosition < MAX_MEMBERS && content[currentPosition] != null;
        }
        public Object next() {
            return content[currentPosition++];
        }
        public void remove() {
            throw new UnsupportedOperationException();
        }
    } // class SimpleSetIterator

    public java.util.Iterator iterator() {
        return new SimpleSetIterator(this);
    }

    public boolean contains(Object o) {
        for (int i = 0; i < MAX_MEMBERS; ++i)
            if (content[i] != null && content[i].equals(o))
                return true;
        return false;
    }

    boolean add(Object o) throws SimpleSetFullException {
        if (contains(o))
            return false;
        for (int i = 0; i < MAX_MEMBERS; ++i) {
            if (content[i] == null) {
                content[i] = o;
                return true;
            }
        }
        throw new SimpleSetFullException();
    }

    public static void main(String[] args) {
        System.out.println("Testing SimpleSet");

        SimpleSet s = new SimpleSet();
        Point p1 = new Point(1, 2);
        Point p2 = new Point(2, 3);
        Point p3 = new Point(3, 4);
        Point p4 = new Point(4, 5);
        Point p5 = new Point(1, 2);

        assert s.contains(p1) == false;
        assert s.contains(p2) == false;
        assert s.contains(p3) == false;
        assert s.contains(p4) == false;
        assert s.contains(p5) == false;

        try {
            assert s.add(p1) == true;
            assert s.add(p1) == false;
        }
        catch (SimpleSetFullException ssfe) {
            assert false;
        }

        assert s.contains(p1) == true;
        assert s.contains(p2) == false;
        assert s.contains(p3) == false;
        assert s.contains(p4) == false;
        assert s.contains(p5) == true;

        try {
            assert s.add(p2) == true;
            assert s.add(p2) == false;
        }
        catch (SimpleSetFullException ssfe) {
            assert false;
        }

        assert s.contains(p1) == true;
        assert s.contains(p2) == true;
        assert s.contains(p3) == false;
        assert s.contains(p4) == false;
        assert s.contains(p5) == true;

        try {
            assert s.add(p3) == true;
            assert s.add(p3) == false;
        }
        catch (SimpleSetFullException ssfe) {
            assert false;
        }

        assert s.contains(p1) == true;
        assert s.contains(p2) == true;
        assert s.contains(p3) == true;
        assert s.contains(p4) == false;
        assert s.contains(p5) == true;

        try {
            s.add(p4);
            assert false;
        }
        catch (SimpleSetFullException ssfe) {

        }

        assert s.contains(p1) == true;
        assert s.contains(p2) == true;
        assert s.contains(p3) == true;
        assert s.contains(p4) == false;
        assert s.contains(p5) == true;

        java.util.Iterator i = s.iterator();
        int n = 0;
        while (i.hasNext()) {
            Point p = (Point)i.next();
            assert p != null;
            ++n;
        }
        assert n == 3;

        System.out.println("SimpleSet ok");
    }
} // class SimpleSet