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/**
 *  Copyright (c) 1997-2013, tinygroup.org ([email protected]).
 *
 *  Licensed under the GPL, Version 3.0 (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.gnu.org/licenses/gpl.html
 *
 *  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.
 * --------------------------------------------------------------------------
 *  版权 (c) 1997-2013, tinygroup.org ([email protected]).
 *
 *  本开源软件遵循 GPL 3.0 协议;
 *  如果您不遵循此协议，则不被允许使用此文件。
 *  你可以从下面的地址获取完整的协议文本
 *
 *       http://www.gnu.org/licenses/gpl.html
 */
package org.tinygroup.different.impl;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

import org.tinygroup.different.DataWithOperation;
import org.tinygroup.different.Different;

/**
 * 差异化比较抽象类

 * 主要用于实现公共方法或通家长方法
 * 
 * @author luoguo
 * 
 * @param 
 *            要比较的实体
 */
public abstract class AbstractDifferentImpl> implements
		Different {

	protected List oldList = null;
	protected Comparator comparator = null;

	public void setObjectComparator(Comparator comparator) {
		this.comparator = comparator;

	}

	public List> differentOrdered(List newList) {
		List> result = null;
		if (newList != null) {
			Collections.sort(newList);
		}
		if (this.oldList == null) {// 如果原来没有，则直接返回
			result = getNewList(newList);
		} else if (newList == null) {// 如果新的没有，则置空
			result = getRemoveList(oldList);
		} else {
			result = getDifferentList(this.oldList, newList);
		}
		this.oldList = newList;
		return result;
	}

	protected List> getNewList(List newList) {
		List> list = new ArrayList>();
		if (newList != null) {
			for (T data : newList) {
				list.add(new DataWithOperation(DataWithOperation.ADD, data));
			}
		}
		return list;
	}

	protected List> getRemoveList(List oldList) {
		List> list = new ArrayList>();
		for (T data : oldList) {
			list.add(new DataWithOperation(DataWithOperation.REMOVE, data));
		}
		return list;
	}

	protected int compare(T oldObject, T newObject) {
		if (comparator != null) {
			return comparator.compare(oldObject, newObject);
		} else {
			return oldObject.compareTo(newObject);
		}
	}

	protected List> getDifferentList(List oldList,
			List newList) {
		List> result = new ArrayList>();
		int oldPos = 0, newPos = 0;
		while (oldPos < oldList.size() && newPos < newList.size()) {
			T oldObject = oldList.get(oldPos);
			T newObject = newList.get(newPos);
			if (oldObject.compareTo(newObject) == 0) {
				// 如果相等,则两个同时相加
				if (compare(oldObject, newObject) != 0) {
					result.add(new DataWithOperation(
							DataWithOperation.MODIFY, newObject));
				}
				oldPos++;
				newPos++;

				continue;
			}
			if (oldObject.compareTo(newObject) < 0) {
				result.add(new DataWithOperation(DataWithOperation.REMOVE,
						oldList.get(oldPos++)));
				continue;
			}
			if (newObject.compareTo(oldObject) < 0) {
				result.add(new DataWithOperation(DataWithOperation.ADD,
						newList.get(newPos++)));
				continue;
			}
		}
		while (newPos < newList.size()) {
			result.add(new DataWithOperation(DataWithOperation.ADD, newList
					.get(newPos++)));
		}
		while (oldPos < oldList.size()) {
			result.add(new DataWithOperation(DataWithOperation.REMOVE,
					oldList.get(oldPos++)));
		}
		return result;
	}

}