TypePropertyIdentityStrategyResolver.java

/*
 * 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.identity;

import de.danielbechler.diff.node.DiffNode;
import de.danielbechler.util.Assert;

import java.util.HashMap;
import java.util.Map;

public class TypePropertyIdentityStrategyResolver
{
	private final Map<PropertyId, IdentityStrategy> strategies = new HashMap<PropertyId, IdentityStrategy>();

	public IdentityStrategy resolve(final DiffNode node)
	{
		if (isQualified(node))
		{
			final PropertyId propertyKey = new PropertyId(node.getParentNode().getValueType(), node.getPropertyName());
			return strategies.get(propertyKey);
		}
		return null;
	}

	private static boolean isQualified(final DiffNode node)
	{
		if (node.isPropertyAware())
		{
			if (node.getParentNode() == null || node.getParentNode().getValueType() == null)
			{
				return false;
			}
			if (node.getPropertyName() == null)
			{
				return false;
			}
			return true;
		}
		return false;
	}

	public void setStrategy(final IdentityStrategy identityStrategy, final Class<?> type, final String... properties)
	{
		for (final String property : properties)
		{
			strategies.put(new PropertyId(type, property), identityStrategy);
		}
	}

	private static class PropertyId
	{
		private final Class<?> type;
		private final String property;

		private PropertyId(final Class<?> type, final String property)
		{
			Assert.notNull(type, "type");
			Assert.notNull(property, "property");
			this.type = type;
			this.property = property;
		}

		@Override
		public int hashCode()
		{
			int result = type.hashCode();
			result = 31 * result + property.hashCode();
			return result;
		}

		@Override
		public boolean equals(final Object o)
		{
			if (this == o)
			{
				return true;
			}
			if (o == null || getClass() != o.getClass())
			{
				return false;
			}

			final PropertyId that = (PropertyId) o;

			if (!property.equals(that.property))
			{
				return false;
			}
			if (!type.equals(that.type))
			{
				return false;
			}

			return true;
		}
	}
}