TripleOrderConvert.java

/**
 * File: $HeadURL: https://hdt-java.googlecode.com/svn/trunk/hdt-java/src/org/rdfhdt/hdt/triples/impl/TripleOrderConvert.java $
 * Revision: $Rev: 191 $
 * Last modified: $Date: 2013-03-03 11:41:43 +0000 (dom, 03 mar 2013) $
 * Last modified by: $Author: mario.arias $
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Contacting the authors:
 *   Mario Arias:               mario.arias@deri.org
 *   Javier D. Fernandez:       jfergar@infor.uva.es
 *   Miguel A. Martinez-Prieto: migumar2@infor.uva.es
 *   Alejandro Andres:          fuzzy.alej@gmail.com
 */

package org.rdfhdt.hdt.triples.impl;

import org.rdfhdt.hdt.enums.TripleComponentOrder;
import org.rdfhdt.hdt.triples.TripleID;

/**
 * @author mario.arias
 *
 */
public class TripleOrderConvert {
    /* This table reflects the swaps needed to convert from
	a SRC ComponentOrder to a DST ComponentOrder.

	There are three swaps possible:
	swap1 (x and y)
	swap2 (y and z)
	swap3 (x and z)

	The order of swaps is important, there are five different:
	 xy   12
	 xz   13
	 yz   23
	 xyz1 12 13
	 xyz2 12 23

	 SRC
	 v
	      SPO  SOP  PSO  POS  OSP  OPS   <DEST
	 SPO       yz   xy   xyz2 xyz1 xz
	 SOP  yz        xyz1 xz   xy   xyz2
	 PSO  xy   xyz2      yz   xz   xyz1
	 POS  xyz1 xz   yz        xyz2
	 OSP  xyz2 xy   xz   xyz1      yz
	 OPS  xz   xyz1 xyz2 xy   yz
	 */
	
	// swap 1-2
    //xy xyz1 xyz2
    private static final boolean [][] swap1tab = new boolean[][] {
                {false, false, true, true, true, false},
                {false, false, true, false, true, true},
                {true, true, false, false, false, true},
                {true, false, false, false, true, false},
                {true, true, false, true, false, false},
                {false, true, true, true, false, false}
    };

    // swap 1-3
    // xz xyz1
    private static final boolean [][] swap2tab = new boolean[][] {
                {false, false, false, false, true, true},
                {false, false, true, true, false, false},
                {false, false, false, false, true, true},
                {true, true, false, false, false, false},
                {false, false, true, true, false, false},
                {true, true, false, false, false, false}
    };

    // swap 2-3
    // yz xyz2
    private static final boolean [][] swap3tab = new boolean[][] {
                {false, true, false, true, false, false},
                {true, false, false, false, false, true},
                {false, true, false, true, false, false},
                {false, false, true, false, true, false},
                {true, false, false, false, false, true},
                {false, false, true, false, true, false}
    };
    
    private TripleOrderConvert() {}
	
	public static void swapComponentOrder(TripleID triple, TripleComponentOrder from, TripleComponentOrder to) {
		if(from==to) {
			return;
		}
		if(from==TripleComponentOrder.Unknown || to==TripleComponentOrder.Unknown) {
			throw new IllegalArgumentException("Cannot swap Unknown Orders");
		}
		boolean swap1 = swap1tab[from.ordinal() - 1][to.ordinal() - 1];
        boolean swap2 = swap2tab[from.ordinal() - 1][to.ordinal() - 1];
        boolean swap3 = swap3tab[from.ordinal() - 1][to.ordinal() - 1];
		
        if(swap1){
            int tmp = triple.getSubject();
            triple.setSubject(triple.getPredicate());
            triple.setPredicate(tmp);
        }
        if(swap2){
            int tmp = triple.getSubject();
            triple.setSubject(triple.getObject());
            triple.setObject(tmp);
        }
        if(swap3){
            int tmp = triple.getPredicate();
            triple.setPredicate(triple.getObject());
            triple.setObject(tmp);
        }
	}
}