ExtendedDimacsArrayReader.java

/*******************************************************************************
* SAT4J: a SATisfiability library for Java Copyright (C) 2004-2008 Daniel Le Berre
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU Lesser General Public License Version 2.1 or later (the
* "LGPL"), in which case the provisions of the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of the LGPL, and not to allow others to use your version of
* this file under the terms of the EPL, indicate your decision by deleting
* the provisions above and replace them with the notice and other provisions
* required by the LGPL. If you do not delete the provisions above, a recipient
* may use your version of this file under the terms of the EPL or the LGPL.
* 
* Based on the original MiniSat specification from:
* 
* An extensible SAT solver. Niklas Een and Niklas Sorensson. Proceedings of the
* Sixth International Conference on Theory and Applications of Satisfiability
* Testing, LNCS 2919, pp 502-518, 2003.
*
* See www.minisat.se for the original solver in C++.
* 
*******************************************************************************/
package org.sat4j.tools;

import org.sat4j.core.VecInt;
import org.sat4j.specs.ContradictionException;
import org.sat4j.specs.ISolver;
import org.sat4j.specs.IVecInt;

/**
 * Reader for the Extended Dimacs format proposed by Fahiem Bacchus and Toby
 * Walsh in array representation (without the terminating 0).
 * 
 * Adaptation of org.sat4j.reader.ExtendedDimacsReader.
 * 
 * @author leberre
 * @author fuhs
 */
public class ExtendedDimacsArrayReader extends DimacsArrayReader {

    public static final int FALSE = 1;

    public static final int TRUE = 2;

    public static final int NOT = 3;

    public static final int AND = 4;

    public static final int NAND = 5;

    public static final int OR = 6;

    public static final int NOR = 7;

    public static final int XOR = 8;

    public static final int XNOR = 9;

    public static final int IMPLIES = 10;

    public static final int IFF = 11;

    public static final int IFTHENELSE = 12;

    public static final int ATLEAST = 13;

    public static final int ATMOST = 14;

    public static final int COUNT = 15;

    private static final long serialVersionUID = 1L;

    private final GateTranslator gater;
    
    public ExtendedDimacsArrayReader(ISolver solver) {
        super(solver);
        gater = new GateTranslator(solver);
    }

    /**
     * Handles a single constraint (constraint == Extended Dimacs circuit gate).
     * 
     * @param gateType
     *            the type of the gate in question
     * @param output
     *            the number of the output of the gate in question
     * @param inputs
     *            the numbers of the inputs of the gates in question; the array
     *            must have the corresponding length for the gate type unless
     *            arbitrary lengths are allowed (i.e., 0 for TRUE and FALSE,
     *            1 for NOT, or 3 for ITE)
     * @return true
     */
    @Override
    protected boolean handleConstr(int gateType, int output, int[] inputs)
            throws ContradictionException {
        IVecInt literals;
        switch (gateType) {
        case FALSE:
            assert inputs.length == 0;
            gater.gateFalse(output);
            break;
        case TRUE:
            assert inputs.length == 0;
            gater.gateTrue(output);
            break;
        case OR:
            literals = new VecInt(inputs);
            gater.or(output, literals);
            break;
        case NOT:
            assert inputs.length == 1;
            gater.not(output, inputs[0]);
            break;
        case AND:
            literals = new VecInt(inputs);
            gater.and(output, literals);
            break;
        case XOR:
            literals = new VecInt(inputs);
            gater.xor(output, literals);
            break;
        case IFF:
            literals = new VecInt(inputs);
            gater.iff(output, literals);
            break;
        case IFTHENELSE:
            assert inputs.length == 3;
            gater.ite(output, inputs[0], inputs[1], inputs[2]);
            break;
        default:
            throw new UnsupportedOperationException("Gate type " + gateType
                    + " not handled yet");
        }
        return true;
    }
}