/*******************************************************************************
* 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.minisat.learning;

import org.sat4j.minisat.core.Constr;
import org.sat4j.minisat.core.DataStructureFactory;
import org.sat4j.minisat.core.ILits;

/**
 * Selects the constraints to learn according to its length as a percentage of 
 * the total number of variables in the solver universe.
 * 
 * @author daniel
 *
 */
public class PercentLengthLearning<L extends ILits,D extends DataStructureFactory<L>> extends LimitedLearning<L,D>{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private int maxpercent;
    private int bound;
    
    public PercentLengthLearning() {
        this(10);
    }
    
    public PercentLengthLearning(int percent) {
        maxpercent = percent;
    }
    
    public void setLimit(int percent) {
        maxpercent = percent;
    }
    
    public int getLimit() {
        return maxpercent;
    }

    @Override
    public void init() {
        super.init();
        setBound(lits.realnVars() * maxpercent / 100);
    }

    @Override
    public String toString() {
        return "Limit learning to clauses of size smaller or equal to " //$NON-NLS-1$
                + maxpercent + "% of the number of variables"; //$NON-NLS-1$
    }

    protected void setBound(int newbound) {
        bound = newbound;
    }

    @Override
    protected boolean learningCondition(Constr constr) {
        return constr.size() <= bound;
    }

}