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Open-source constraint solver.
/**
* Copyright (c) 2016, Ecole des Mines de Nantes
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the .
* 4. Neither the name of the nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.chocosolver.solver.objective;
import org.chocosolver.solver.ResolutionPolicy;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.variables.RealVar;
import org.chocosolver.solver.variables.Variable;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.function.Function;
/**
* Factory to create (mono-)objective managers.
*
* @author Arnaud Malapert
*/
public final class ObjectiveFactory {
private ObjectiveFactory() {
super();
}
/**
* Define a manager for satisfaction problems.
*
* @return a singleton object
*/
public static IObjectiveManager SAT() {
return SATManager.getInstance();
}
/**
* Define the variable to optimize (maximize or minimize)
* By default, the manager uses {@link IObjectiveManager#setStrictDynamicCut()} to avoid exploring worse solutions.
*
* @param objective variable to optimize
* @param policy {{@link ResolutionPolicy#MINIMIZE}/{@link ResolutionPolicy#MAXIMIZE}
* @return the objective manager
* @throws IllegalArgumentException if the policy is {@link ResolutionPolicy#SATISFACTION}.
*/
public static IObjectiveManager makeObjectiveManager(IntVar objective, ResolutionPolicy policy) {
IObjectiveManager objman;
switch (policy) {
case MINIMIZE:
objman = new MinIntObjManager(objective);
break;
case MAXIMIZE:
objman = new MaxIntObjManager(objective);
break;
default:
throw new IllegalArgumentException("cant build integer objective manager :" + policy);
}
objman.setStrictDynamicCut();
return objman;
}
/**
* Define the variable to optimize (maximize or minimize)
* By default, the manager uses {@link IObjectiveManager#setStrictDynamicCut()} to avoid exploring worse solutions.
*
* @param objective variable to optimize
* @param policy {{@link ResolutionPolicy#MINIMIZE}/{@link ResolutionPolicy#MAXIMIZE}
* @return the objective manager
* @throws IllegalArgumentException if the policy is {@link ResolutionPolicy#SATISFACTION}.
*/
public static IObjectiveManager makeObjectiveManager(RealVar objective, ResolutionPolicy policy, double precision) {
IObjectiveManager objman;
switch (policy) {
case MINIMIZE:
objman = new MinRealObjManager(objective, precision);
break;
case MAXIMIZE:
objman = new MaxRealObjManager(objective, precision);
break;
default:
throw new IllegalArgumentException("cant build real objective manager :" + policy);
}
objman.setStrictDynamicCut();
return objman;
}
/**
* @param object to copy
* @return copy built by a copy constructor if one exists, otherwise the parameter.
*/
@SuppressWarnings("unchecked")
public static V copy(V object) {
try {
Class c = object.getClass();
// Use the "copy constructor":
Constructor ct = c.getConstructor(c);
return (V) ct.newInstance(object);
} catch (NoSuchMethodException | SecurityException | InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
// fails silently
}
return object;
}
}
/**
* A class for CSP (in opposition to COP) which matches {@link IObjectiveManager} requisites.
*/
final class SATManager implements IObjectiveManager {
private static final long serialVersionUID = 2115489336441115889L;
private final static SATManager INSTANCE = new SATManager();
public final static SATManager getInstance() {
return INSTANCE;
}
private SATManager() {}
/**
* readResolve method to preserve singleton property
*/
private Object readResolve() {
// Return the one true INSTANCE and let the garbage collector
// take care of the INSTANCE impersonator.
return INSTANCE;
}
@Override
public ResolutionPolicy getPolicy() {
return ResolutionPolicy.SATISFACTION;
}
@Override
public boolean isOptimization() {
return false;
}
@Override
public Number getBestLB() {
throw new UnsupportedOperationException("There is no objective bounds in satisfaction problems");
}
@Override
public Number getBestUB() {
throw new UnsupportedOperationException("There is no objective bounds in satisfaction problems");
}
@Override
public void updateBestLB(Number lb) {
throw new UnsupportedOperationException("There is no objective bounds in satisfaction problems");
}
@Override
public void updateBestUB(Number ub) {
throw new UnsupportedOperationException("There is no objective bounds in satisfaction problems");
}
@Override
public Number getBestSolutionValue() {
throw new UnsupportedOperationException("There is no objective variable in satisfaction problems");
}
@Override
public Variable getObjective() {
return null;
}
@Override
public void updateBestSolution(Number n) {
throw new UnsupportedOperationException("not a mono-objective optimization problem");
}
@Override
public void updateBestSolution() {
// nothing to do
}
@Override
public void setWalkingDynamicCut() {
// nothing to do
}
@Override
public void setStrictDynamicCut() {
// nothing to do
}
@Override
public void setCutComputer(Function cutComputer) {
// nothing to do
}
@Override
public void postDynamicCut() throws ContradictionException {
// nothing to do
}
@Override
public String toString() {
return "SAT";
}
}