/* * Data Hub Service (DHuS) - For Space data distribution. * Copyright (C) 2016 GAEL Systems * * This file is part of DHuS software sources. * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as * published by the Free Software Foundation, either version 3 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package fr.gael.dhus.util.functional; import fr.gael.dhus.util.functional.tuple.Duo; import org.apache.commons.collections4.Transformer; /** * Comparator as a Transformer accepting a Duo<? extends Comparable, ? extends Comparable> * as input. */ public class ComparatorTransformer implements Transformer<Duo<? extends Comparable, ? extends Comparable>, Integer> { private final boolean reverse; /** * Creates a new ComparatorTransformer in ascending order. */ public ComparatorTransformer() { this.reverse = false; } /** * Create a new ComparatorTransformer. * @param reverse if `true`, reverse parameters (descending order). */ public ComparatorTransformer(boolean reverse) { this.reverse = reverse; } @Override public Integer transform(Duo<? extends Comparable, ? extends Comparable> params) { if (params.getA() == null && params.getB() == null) { return 0; } if (this.reverse) { if (params.getB() == null) { return - params.getA().compareTo(null); } return params.getB().compareTo(params.getA()); } if (params.getA() == null) { return - params.getB().compareTo(null); } return params.getA().compareTo(params.getB()); } }