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 class Clause {
027    private Atom head;
028    private Body body;
029    
030    public Clause(Atom head, Body body) {
031        this.head = head;
032        this.body = body;
033        if (body == null)
034            this.body = new Body();
035    }
036
037    @Override
038        public String toString() {
039        if (body.isEmpty())
040            return head+".";
041        return head + " :- " + body +".";
042    }
043
044    public String toPLString() {
045        if (body.isEmpty())
046            return head.toPLString()+".";
047        return head.toPLString() + " :- " + body.toPLString() +".";
048    }
049
050    public boolean isGround() {
051        if (!head.isGround())
052            return false;
053        
054        return body.isGround();
055    }
056
057    public Body getBody() {
058        return body;
059    }
060
061    public Atom getHead() {
062        return head;
063    }
064    
065    /**
066         * 
067         * @param variable
068         *            Substitution variable.
069         * @param term
070         *            A term.
071         * @return Returns a new instance of this term, where the variable is
072         *         replaced by the term.
073         */    
074    public Clause getInstance(Variable variable, Term term) {
075        Atom newhead = head.getInstance(variable, term);
076        Body newbody = body.getInstance(variable, term);
077        
078        return new Clause(newhead, newbody);
079    }
080
081}
082