001/**
002 * Copyright (C) 2007 - 2016, Jens Lehmann
003 *
004 * This file is part of DL-Learner.
005 *
006 * DL-Learner is free software; you can redistribute it and/or modify
007 * it under the terms of the GNU General Public License as published by
008 * the Free Software Foundation; either version 3 of the License, or
009 * (at your option) any later version.
010 *
011 * DL-Learner is distributed in the hope that it will be useful,
012 * but WITHOUT ANY WARRANTY; without even the implied warranty of
013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
014 * GNU General Public License for more details.
015 *
016 * You should have received a copy of the GNU General Public License
017 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
018 */
019package org.dllearner.algorithms.el;
020
021import java.util.Comparator;
022
023/**
024 * Compares two EL OWLClassExpression trees by calling {@link ELDescriptionNodeComparator} 
025 * on their root nodes.
026 * 
027 * @author Jens Lehmann
028 *
029 */
030public class ELDescriptionTreeComparator implements Comparator<ELDescriptionTree> {
031
032        private ELDescriptionNodeComparator nodeComp;
033        
034        public ELDescriptionTreeComparator() {
035                nodeComp = new ELDescriptionNodeComparator();
036        }
037        
038        /* (non-Javadoc)
039         * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
040         */
041        @Override
042        public int compare(ELDescriptionTree tree1, ELDescriptionTree tree2) {
043                // we use the size as first criterion to avoid many comparisons
044                int sizeDiff = tree1.size - tree2.size;
045                if(sizeDiff == 0) {
046                        ELDescriptionNode node1 = tree1.getRootNode();
047                        ELDescriptionNode node2 = tree2.getRootNode();
048                        return nodeComp.compare(node1, node2);                  
049                } else { 
050                        return sizeDiff;
051                }
052        }
053
054}