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}