/*
* 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<Object> changed = new ArrayList<Object>(working);
changed.removeAll(addedItemsOf(instances));
changed.removeAll(removedItemsOf(instances));
return changed;
}
public boolean accepts(final Class<?> type)
{
return Collection.class.isAssignableFrom(type);
}
public final DiffNode compare(final DiffNode parentNode, final Instances collectionInstances)
{
final DiffNode collectionNode = newNode(parentNode, collectionInstances);
if (collectionInstances.hasBeenAdded())
{
final Collection addedItems = collectionInstances.getWorking(Collection.class);
compareItems(collectionNode, collectionInstances, addedItems);
collectionNode.setState(DiffNode.State.ADDED);
}
else if (collectionInstances.hasBeenRemoved())
{
final Collection<?> removedItems = collectionInstances.getBase(Collection.class);
compareItems(collectionNode, collectionInstances, removedItems);
collectionNode.setState(DiffNode.State.REMOVED);
}
else if (collectionInstances.areSame())
{
collectionNode.setState(DiffNode.State.UNTOUCHED);
}
else
{
final ComparisonStrategy comparisonStrategy = comparisonStrategyResolver.resolveComparisonStrategy(collectionNode);
if (comparisonStrategy == null)
{
compareInternally(collectionNode, collectionInstances);
}
else
{
compareUsingComparisonStrategy(collectionNode, collectionInstances, comparisonStrategy);
}
}
return collectionNode;
}
private void compareInternally(final DiffNode collectionNode, final Instances collectionInstances)
{
compareItems(collectionNode, collectionInstances, addedItemsOf(collectionInstances));
compareItems(collectionNode, collectionInstances, removedItemsOf(collectionInstances));
compareItems(collectionNode, collectionInstances, knownItemsOf(collectionInstances));
}
private void compareItems(final DiffNode collectionNode,
final Instances collectionInstances,
final Iterable<?> items)
{
for (final Object item : items)
{
final Accessor itemAccessor = new CollectionItemAccessor(item);
differDispatcher.dispatch(collectionNode, collectionInstances, itemAccessor);
}
}
}