/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.tools.math.container;

import java.util.Comparator;
import java.util.PriorityQueue;

/**
 * This class implements a bounded priority queue which contains always the n-th smalles values.
 * If a new value is added, it is added only if it is smaller than the greatest value already in queue.
 * The greatest value is then removed. The iterator does not iterate in any particular order.
 * This queue will implement a reverse order in compare with the java PriorityQueue, so 
 * peek and poll will retrieve the greatest elements  
 * 
 * @author Sebastian Land
 *
 * @param <E>
 */
public class BoundedPriorityQueue<E> extends PriorityQueue<E> {

	private static final long serialVersionUID = 6020635755912950637L;

	private final int bound;
	private final Comparator<E> comparator;
	
	public BoundedPriorityQueue(int bound) {
		super(bound, new ReverseComparableComparator<E>());
		this.comparator = new ReverseComparableComparator<E>();
		this.bound = bound;
	}

	public BoundedPriorityQueue(int bound, Comparator<? super E> comp) {
		super(bound, new ReverseComparator<E>(comp));
		this.bound = bound;
		this.comparator = new ReverseComparator<E>(comp);
	}

	@Override
	public boolean offer(E e) {
		if (size() == bound) {
			E head = peek();
			// test with Reverse(!) comparator if e is smaller: Test if greater
			if (comparator.compare(e, head) > 0) {
				// if smaller: remove biggest and add e
				poll();
				return super.offer(e);
			}
		} else {
			return super.offer(e);
		}
		return false;
	}
	
	@Override
	public boolean add(E e) {
		return offer(e);
	}
	
	public boolean isFilled() {
		return (size() == bound);
	}
}