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.prolog;
020
021/**
022 * 
023 * @author Sebastian Bader
024 * 
025 */
026public abstract class Term implements Cloneable {
027
028        /**
029         * 
030         * @return Returns true iff this term is ground
031         */
032        public abstract boolean isGround();
033
034        /**
035         * 
036         * @param variable
037         *            Substitution variable.
038         * @param term
039         *            A term.
040         * @return Returns a new instance of this term, where the variable is
041         *         replaced by the term.
042         */
043        public abstract Term getInstance(Variable variable, Term term);
044
045        @Override
046        public abstract boolean equals(Object obj);
047
048        @Override
049        public abstract int hashCode();
050
051        @Override
052        public abstract Object clone();
053
054        @Override
055        public abstract String toString();
056
057        public abstract String toPLString();
058
059}