MapComparator.java

/* 
 * Copyright 2006 the original author or authors.
 *
 * 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.
 *
 * Modified by Clam <clamisgood@gmail.com>
 *  
 * This file is part of LateralGM.
 * LateralGM is free software and comes with ABSOLUTELY NO WARRANTY.
 * See LICENSE for details.
 */

package org.lateralgm.compare;

import java.util.Map;
import java.util.Set;
import java.util.Stack;

/**
 * @author Filip Neven
 * @author Tim Ducheyne
 */
public class MapComparator extends ReflectionComparator
	{
	public MapComparator(ReflectionComparator chainedComparator)
		{
		super(chainedComparator);
		}

	public boolean canHandle(Object left, Object right)
		{
		return (left != null && right != null)
				&& (left instanceof Map<?,?> && right instanceof Map<?,?>);
		}

	protected Difference doGetDifference(Object left, Object right, Stack<String> fieldStack,
			Set<TraversedInstancePair> traversedInstancePairs)
		{
		Map<?,?> leftMap = (Map<?,?>) left;
		Map<?,?> rightMap = (Map<?,?>) right;

		if (leftMap.size() != rightMap.size())
			{
			return new Difference("Different map sizes.",left,right,fieldStack);
			}

		for (Map.Entry<?,?> lhsEntry : leftMap.entrySet())
			{
			Object lhsKey = lhsEntry.getKey();

			fieldStack.push("" + lhsKey);
			Object lhsValue = lhsEntry.getValue();
			Object rhsValue = rightMap.get(lhsKey);
			Difference difference = rootComparator.getDifference(lhsValue,rhsValue,fieldStack,
					traversedInstancePairs);
			if (difference != null)
				{
				return difference;
				}
			fieldStack.pop();
			}
		return null;
		}
	}