/*
 * Copyright 1999-2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.collections;

import java.util.Comparator;

/**
 * A type of {@link Bag} that maintains order among its unique
 * representative members.
 *
 * @since 2.0
 * @author Chuck Burdick
 **/
public interface SortedBag extends Bag {

   /**
    * Returns the comparator associated with this sorted set, or null
    * if it uses its elements' natural ordering.
    **/
   public Comparator comparator();

   /**
    * Returns the first (lowest) member.
    **/
   public Object first();

   /**
    * Returns the last (highest) member.
    **/
   public Object last();
}
