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Framework to detect and handle differences between Java objects
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/*
 * Copyright 2014 Daniel Bechler
 *
 * 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 de.danielbechler.diff.differ;

import de.danielbechler.diff.access.Accessor;
import de.danielbechler.diff.access.CollectionItemAccessor;
import de.danielbechler.diff.access.Instances;
import de.danielbechler.diff.comparison.ComparisonStrategy;
import de.danielbechler.diff.comparison.ComparisonStrategyResolver;
import de.danielbechler.diff.node.DiffNode;
import de.danielbechler.util.Assert;
import de.danielbechler.util.Collections;

import java.util.ArrayList;
import java.util.Collection;

/**
 * Used to find differences between {@link Collection Collections}.
 *
 * @author Daniel Bechler
 */
public final class CollectionDiffer implements Differ
{
	private final DifferDispatcher differDispatcher;
	private final ComparisonStrategyResolver comparisonStrategyResolver;

	public CollectionDiffer(final DifferDispatcher differDispatcher,
							final ComparisonStrategyResolver comparisonStrategyResolver)
	{
		Assert.notNull(differDispatcher, "differDispatcher");
		this.differDispatcher = differDispatcher;

		Assert.notNull(comparisonStrategyResolver, "comparisonStrategyResolver");
		this.comparisonStrategyResolver = comparisonStrategyResolver;
	}

	private static void compareUsingComparisonStrategy(final DiffNode collectionNode,
													   final Instances collectionInstances,
													   final ComparisonStrategy comparisonStrategy)
	{
		comparisonStrategy.compare(collectionNode, collectionInstances.getType(), collectionInstances.getWorking(Collection.class), collectionInstances.getBase(Collection.class));
	}

	private static DiffNode newNode(final DiffNode parentNode, final Instances collectionInstances)
	{
		final Accessor accessor = collectionInstances.getSourceAccessor();
		final Class type = collectionInstances.getType();
		return new DiffNode(parentNode, accessor, type);
	}

	private static Collection addedItemsOf(final Instances instances)
	{
		final Collection working = instances.getWorking(Collection.class);
		final Collection base = instances.getBase(Collection.class);
		return Collections.filteredCopyOf(working, base);
	}

	private static Collection removedItemsOf(final Instances instances)
	{
		final Collection working = instances.getWorking(Collection.class);
		final Collection base = instances.getBase(Collection.class);
		return Collections.filteredCopyOf(base, working);
	}

	private static Iterable knownItemsOf(final Instances instances)
	{
		final Collection working = instances.getWorking(Collection.class);
		final Collection