/*******************************************************************************
* 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;
import org.sat4j.specs.TimeoutException;

/**
 * That class allows to iterate through all the models (implicants) of a
 * formula.
 * 
 * <pre>
 * ISolver solver = new ModelIterator(SolverFactory.OneSolver());
 * boolean unsat = true;
 * while (solver.isSatisfiable()) {
 *     unsat = false;
 *     int[] model = solver.model();
 *     // do something with model
 * }
 * if (unsat) {
 *     // UNSAT case
 * }
 * </pre>
 * 
 * @author leberre
 */
public class ModelIterator extends SolverDecorator<ISolver> {

    private static final long serialVersionUID = 1L;

    private boolean trivialfalsity = false;

    /**
     * @param solver
     */
    public ModelIterator(ISolver solver) {
        super(solver);
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.sat4j.ISolver#model()
     */
    @Override
    public int[] model() {
        int[] last = super.model();
        IVecInt clause = new VecInt(last.length);
        for (int q : last) {
            clause.push(-q);
        }
        try {
            // System.out.println("adding " + clause);
            addClause(clause);
        } catch (ContradictionException e) {
            trivialfalsity = true;
        }
        return last;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.sat4j.ISolver#isSatisfiable()
     */
    @Override
    public boolean isSatisfiable() throws TimeoutException {
        if (trivialfalsity) {
            return false;
        }
        trivialfalsity = false;
        return super.isSatisfiable(true);
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.sat4j.ISolver#isSatisfiable(org.sat4j.datatype.VecInt)
     */
    @Override
    public boolean isSatisfiable(IVecInt assumps) throws TimeoutException {
        if (trivialfalsity) {
            return false;
        }
        trivialfalsity = false;
        return super.isSatisfiable(assumps,true);
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.sat4j.ISolver#reset()
     */
    @Override
    public void reset() {
        trivialfalsity = false;
        super.reset();
    }
}