/*******************************************************************************
* 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();
}
}