priorityqueue.java

一个关于java 的常用工具包

package org.jutil.java.collections;

import java.util.Comparator;

/**
 * <p>A PriorityQueue is a container of objects with an associated priority/ordering,
 * that allows the retrieval of the element with the smallest value. 
 * The order of the elements is determined by a Comparator.</p>
 *
 * <p>See also <a href="http://priority-queues.webhop.org/">priority-queues.webhop.org</a>
 * for more information on priority queues.</p>
 *
 * @path    $Source: /cvsroot/org-jutil/jutil.org/src/org/jutil/java/collections/PriorityQueue.java,v $
 * @version $Revision: 1.5 $
 * @date    $Date: 2002/07/21 17:56:59 $
 * @state   $State: Exp $
 * @author  Tom Schrijvers
 * @author  Marko van Dooren
 * @release $Name:  $
 */
public interface PriorityQueue extends Dispenser{
  
  /* The revision of this class */
  public final static String CVS_REVISION ="$Revision: 1.5 $";

	/**
	 * Return the smallest object in this PriorityQueue.
	 */
 /*@
	 @ public behavior
	 @
	 @ pre ! isEmpty();
	 @
	 @ // The result is in this PriorityQueue.
	 @ post nbExplicitOccurrences(\result) > 0;
	 @ // The result is the minimum element.
	 @ post (\forall Object o; nbExplicitOccurrences(o) > 0;
	 @       ExtendedComparator.ensureExtended(getComparator()).notGreater(o,\result));
	 @*/
	public Object min();

 /*@
   	@ also public behavior
	@
	@ post \result == min();
	@*/
	public Object getNext();
	
	/**
	 * Return the smallest object in this PriorityQueue and
	 * remove it.
	 */
 /*@
	 @ public behavior
	 @
	 @ pre ! isEmpty();
	 @
	 @ // The minimum is returned.
	 @ post \result == \old(min());
	 @ // The instance that is returned, is removed.
	 @ post nbExplicitOccurrences(\result) == \old(nbExplicitOccurrences(getNext())) - 1;
	 @*/
	public Object pop();

	/**
	 * Return the comparator that is used to determine the order of the elements.
	 */
 /*@
	 @ public behavior
	 @
	 @ post \result != null;
	 @*/
	public Comparator getComparator();

}
/*
 * <copyright>Copyright (C) 1997-2001. This software is copyrighted by 
 * the people and entities mentioned after the "@author" tags above, on 
 * behalf of the JUTIL.ORG Project. The copyright is dated by the dates 
 * after the "@date" tags above. All rights reserved.
 * This software is published under the terms of the JUTIL.ORG Software
 * License version 1.1 or later, a copy of which has been included with
 * this distribution in the LICENSE file, which can also be found at
 * http://org-jutil.sourceforge.net/LICENSE. This software is distributed 
 * WITHOUT ANY WARRANTY; without even the implied warranty of 
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 
 * See the JUTIL.ORG Software License for more details. For more information,
 * please see http://org-jutil.sourceforge.net/</copyright>
 */