/*******************************************************************************
* 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.constraints.cnf;
import java.io.Serializable;
import org.sat4j.minisat.core.Constr;
import org.sat4j.minisat.core.ILits;
import org.sat4j.minisat.core.Undoable;
import org.sat4j.minisat.core.UnitPropagationListener;
import org.sat4j.specs.IVecInt;
/**
* @author leberre
*/
public class CBClause implements Constr, Undoable, Serializable {
private static final long serialVersionUID = 1L;
protected int falsified;
private boolean learnt;
protected final int[] lits;
protected final ILits voc;
private double activity;
public static CBClause brandNewClause(UnitPropagationListener s, ILits voc,
IVecInt literals) {
CBClause c = new CBClause(literals, voc);
c.register();
return c;
}
/**
*
*/
public CBClause(IVecInt ps, ILits voc, boolean learnt) {
this.learnt = learnt;
this.lits = new int[ps.size()];
this.voc = voc;
ps.moveTo(this.lits);
}
public CBClause(IVecInt ps, ILits voc) {
this(ps, voc, false);
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#remove()
*/
public void remove() {
for (int i = 0; i < lits.length; i++) {
voc.attaches(lits[i] ^ 1).remove(this);
}
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#propagate(org.sat4j.minisat.core.UnitPropagationListener,
* int)
*/
public boolean propagate(UnitPropagationListener s, int p) {
voc.undos(p).push(this);
falsified++;
assert falsified != lits.length;
if (falsified == lits.length - 1) {
// find unassigned literal
for (int i = 0; i < lits.length; i++) {
if (!voc.isFalsified(lits[i])) {
return s.enqueue(lits[i], this);
}
}
// one of the variable in to be propagated to false.
// (which explains why the falsified counter has not
// been increased yet)
return false;
}
return true;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#simplify()
*/
public boolean simplify() {
for (int p : lits) {
if (voc.isSatisfied(p)) {
return true;
}
}
return false;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#undo(int)
*/
public void undo(int p) {
falsified--;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#calcReason(int,
* org.sat4j.specs.VecInt)
*/
public void calcReason(int p, IVecInt outReason) {
assert outReason.size() == 0;
for (int q : lits) {
assert voc.isFalsified(q) || q == p;
if (voc.isFalsified(q)) {
outReason.push(q ^ 1);
}
}
assert (p == ILits.UNDEFINED) || (outReason.size() == lits.length - 1);
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#learnt()
*/
public boolean learnt() {
return learnt;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#incActivity(double)
*/
public void incActivity(double claInc) {
activity += claInc;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#getActivity()
*/
public double getActivity() {
return activity;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#locked()
*/
public boolean locked() {
for (int p : lits) {
if (voc.isSatisfied(p)) {
return voc.getReason(p) == this;
}
}
return false;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#setLearnt()
*/
public void setLearnt() {
learnt = true;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#register()
*/
public void register() {
for (int p : lits) {
voc.attach(p ^ 1, this);
}
if (learnt) {
for (int p : lits) {
if (voc.isFalsified(p)) {
voc.undos(p ^ 1).push(this);
falsified++;
}
}
assert falsified == lits.length - 1;
}
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#rescaleBy(double)
*/
public void rescaleBy(double d) {
activity *= d;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#size()
*/
public int size() {
return lits.length;
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#get(int)
*/
public int get(int i) {
return lits[i];
}
/*
* (non-Javadoc)
*
* @see org.sat4j.minisat.core.Constr#assertConstraint(org.sat4j.minisat.core.UnitPropagationListener)
*/
public void assertConstraint(UnitPropagationListener s) {
assert voc.isUnassigned(lits[0]);
boolean ret = s.enqueue(lits[0], this);
assert ret;
}
@Override
public String toString() {
StringBuffer stb = new StringBuffer();
for (int i = 0; i < lits.length; i++) {
stb.append(lits[i]);
stb.append("["); //$NON-NLS-1$
stb.append(voc.valueToString(lits[i]));
stb.append("]"); //$NON-NLS-1$
stb.append(" "); //$NON-NLS-1$
}
return stb.toString();
}
}