ParentTypeAwareTypeInformation.java

/*
 * Copyright 2011-2015 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.
 */
package org.springframework.data.util;

import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.HashMap;
import java.util.Map;

/**
 * Base class for {@link TypeInformation} implementations that need parent type awareness.
 * 
 * @author Oliver Gierke
 */
public abstract class ParentTypeAwareTypeInformation<S> extends TypeDiscoverer<S> {

	private final TypeDiscoverer<?> parent;
	private int hashCode;

	/**
	 * Creates a new {@link ParentTypeAwareTypeInformation}.
	 * 
	 * @param type must not be {@literal null}.
	 * @param parent must not be {@literal null}.
	 * @param map must not be {@literal null}.
	 */
	protected ParentTypeAwareTypeInformation(Type type, TypeDiscoverer<?> parent, Map<TypeVariable<?>, Type> map) {

		super(type, mergeMaps(parent, map));
		this.parent = parent;
	}

	/**
	 * Merges the type variable maps of the given parent with the new map.
	 * 
	 * @param parent must not be {@literal null}.
	 * @param map must not be {@literal null}.
	 * @return
	 */
	private static Map<TypeVariable<?>, Type> mergeMaps(TypeDiscoverer<?> parent, Map<TypeVariable<?>, Type> map) {

		Map<TypeVariable<?>, Type> typeVariableMap = new HashMap<>();
		typeVariableMap.putAll(map);
		typeVariableMap.putAll(parent.getTypeVariableMap());

		return typeVariableMap;
	}

	/* 
	 * (non-Javadoc)
	 * @see org.springframework.data.util.TypeDiscoverer#createInfo(java.lang.reflect.Type)
	 */
	@Override
	protected TypeInformation<?> createInfo(Type fieldType) {

		if (parent.getType().equals(fieldType)) {
			return parent;
		}

		return super.createInfo(fieldType);
	}

	/* 
	 * (non-Javadoc)
	 * @see org.springframework.data.util.TypeDiscoverer#equals(java.lang.Object)
	 */
	@Override
	public boolean equals(Object obj) {

		if (!super.equals(obj)) {
			return false;
		}

		if (!this.getClass().equals(obj.getClass())) {
			return false;
		}

		ParentTypeAwareTypeInformation<?> that = (ParentTypeAwareTypeInformation<?>) obj;
		return this.parent == null ? that.parent == null : this.parent.equals(that.parent);
	}

	/* 
	 * (non-Javadoc)
	 * @see org.springframework.data.util.TypeDiscoverer#hashCode()
	 */
	@Override
	public int hashCode() {

		if (this.hashCode == 0) {
			this.hashCode = super.hashCode() + 31 * parent.hashCode();
		}

		return this.hashCode;
	}
}