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/*******************************************************************************
* Copyright (c) 2010-2014, Bergmann Gabor, 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.util;
import java.util.Comparator;
import java.util.Iterator;
/**
* A comparator that compares two iterables based on the lexicographic sorting induced by a comparator on elements.
* @author Bergmann Gabor
*
*/
public class LexicographicComparator<T> implements Comparator<Iterable<? extends T>> {
final Comparator<T> elementComparator;
public LexicographicComparator(Comparator<T> elementComparator) {
super();
this.elementComparator = elementComparator;
}
@Override
public int compare(Iterable<? extends T> o1, Iterable<? extends T> o2) {
Iterator<? extends T> it1 = o1.iterator();
Iterator<? extends T> it2 = o2.iterator();
boolean has1, has2, bothHaveNext;
do {
has1 = it1.hasNext();
has2 = it2.hasNext();
bothHaveNext = has1 && has2;
if (bothHaveNext) {
T element1 = it1.next();
T element2 = it2.next();
int elementComparison = elementComparator.compare(element1, element2);
if (elementComparison != 0)
return elementComparison;
}
} while (bothHaveNext);
if (has1 && !has2) {
return +1;
} else if (!has1 && has2) {
return -1;
} else /*if (!has1 && !has2)*/ {
return 0;
}
}
}
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