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/*******************************************************************************
* Copyright (c) 2010-2012, Tamas Szabo, Istvan Rath and Daniel Varro
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-v20.html.
*
* SPDX-License-Identifier: EPL-2.0
*******************************************************************************/
package tools.refinery.viatra.runtime.rete.itc.alg.util;
import tools.refinery.viatra.runtime.matchers.util.CollectionsFactory;
import java.util.Set;
/**
* @author Tamas Szabo
*
*/
public class CollectionHelper {
private CollectionHelper() {/*Utility class constructor*/}
/**
* Returns the intersection of two sets. It calls {@link Set#retainAll(java.util.Collection)} but returns a new set
* containing the elements of the intersection.
*
* @param set1
* the first set (can be null, interpreted as empty)
* @param set2
* the second set (can be null, interpreted as empty)
* @return the intersection of the sets
* @since 1.7
*/
public static <V> Set<V> intersection(Set<V> set1, Set<V> set2) {
if (set1 == null || set2 == null)
return CollectionsFactory.createSet();
Set<V> intersection = CollectionsFactory.createSet(set1);
intersection.retainAll(set2);
return intersection;
}
/**
* Returns the difference of two sets (S1\S2). It calls {@link Set#removeAll(java.util.Collection)} but returns a
* new set containing the elements of the difference.
*
* @param set1
* the first set (can be null, interpreted as empty)
* @param set2
* the second set (can be null, interpreted as empty)
* @return the difference of the sets
* @since 1.7
*/
public static <V> Set<V> difference(Set<V> set1, Set<V> set2) {
if (set1 == null)
return CollectionsFactory.createSet();
Set<V> difference = CollectionsFactory.createSet(set1);
if (set2 != null) difference.removeAll(set2);
return difference;
}
}
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