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My common library, a mixed bag of re-usable utility code.

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/*
 * Copyright The Sett Ltd, 2005 to 2014.
 *
 * 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 com.thesett.common.util;

/**
 * A Source is the point at which a consumer may take items from a queue. This interface is compatable with
 * java.util.Queue, in that any Queue implementation can also implement this interface with no further work. Source has
 * been created as a seperate interface, to inroduce the possibility of a data structure that only exposes its Source,
 * and hides the remainder of its operations.
 *
 * 
 * 
 * CRC CardResponsibilities
 * 
Take elements from a queue.
 * 
 *
 * @author Rupert Smith
 */
public interface Source
{
    /**
     * Retrieves and removes the head of this queue, or null if this queue is empty.
     *
     * @return The head of this queue, or null if this queue is empty.
     */
    E poll();

    /**
     * Retrieves, but does not remove, the head of this queue, returning null if this queue is empty.
     *
     * @return The head of this queue, or null if this queue is empty.
     */
    E peek();
}