Resolved.java

/**
 * Copyright 2011-2012 Universite Joseph Fourier, LIG, ADELE team
 *   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 fr.imag.adele.apam;

import java.util.HashSet;
import java.util.Set;

/**
 * This object is used to return the result of a resolution, provided a relation.
 * 
 * If the relation is a singleton, the result (if found) must be in singletonResolved, 
 * 		if multiple, in setResolved.
 * 
 * In case the target is an Instance, an that the Implementation is found but no instance is available, 
 *      the Implementation must be provided in toInstantiate, and the other fields at null.
 *      
 *  In all cases, only one field is provided, others are null.
 */

public class Resolved<T extends Component> {
	public Implementation toInstantiate;
	public T singletonResolved;
	public Set<T> setResolved;

	/*
	 * The boolean is useless, only to make a different signature.
	 */
	public Resolved(Implementation impl, boolean toInstanciate) {
		this.toInstantiate = impl;
		this.singletonResolved = null;
		this.setResolved = null;
	}

	public Resolved(Set<T> setResolved) {
		this.singletonResolved = null;
		this.setResolved = setResolved;
	}

	public Resolved(T singletonResolved) {
		this.singletonResolved = singletonResolved;
		this.setResolved = null;
	}

	public boolean isEmpty() {
		return singletonResolved == null && toInstantiate == null && (setResolved == null || setResolved.isEmpty());
	}

	public Resolved<T> merge(Resolved<T> that) {

		Set<T> merged = new HashSet<T>();

		if (singletonResolved != null) {
			merged.add(singletonResolved);
		}

		if (that != null && that.singletonResolved != null) {
			merged.add(that.singletonResolved);
		}

		if (setResolved != null) {
			merged.addAll(setResolved);
		}

		if (that != null && that.setResolved != null) {
			merged.addAll(that.setResolved);
		}

		return new Resolved<T>(merged);
	}
}