/*
* (c) Copyright 2009-2011 by Volker Bergmann. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, is permitted under the terms of the
* GNU General Public License.
*
* For redistributing this software or a derivative work under a license other
* than the GPL-compatible Free Software License as defined by the Free
* Software Foundation or approved by OSI, you must first obtain a commercial
* license to this software product from Volker Bergmann.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* WITHOUT A WARRANTY OF ANY KIND. ALL EXPRESS OR IMPLIED CONDITIONS,
* REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE
* HEREBY EXCLUDED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS 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.databene.benerator.distribution.sequence;
import java.math.BigDecimal;
import org.databene.benerator.Generator;
import org.databene.benerator.InvalidGeneratorSetupException;
import org.databene.benerator.NonNullGenerator;
import org.databene.benerator.distribution.Sequence;
import org.databene.benerator.wrapper.SkipGeneratorProxy;
import org.databene.benerator.wrapper.WrapperFactory;
import org.databene.commons.BeanUtil;
import org.databene.commons.ConfigurationError;
import org.databene.commons.MathUtil;
import org.databene.commons.NumberUtil;
import org.databene.commons.converter.NumberToNumberConverter;
import static org.databene.commons.NumberUtil.*;
/**
* Random Walk {@link Sequence} implementation that supports a variable step width.<br/>
* <br/>
* Created at 30.06.2009 07:48:40
* @since 0.6.0
* @author Volker Bergmann
*/
public class RandomWalkSequence extends Sequence {
private static final BigDecimal ONE = BigDecimal.ONE;
private static final BigDecimal MINUS_ONE = BigDecimal.ZERO.subtract(ONE);
private static final boolean DEFAULT_BUFFERED = false;
private BigDecimal initial;
private BigDecimal minStep;
private BigDecimal maxStep;
private boolean buffered;
// constructors ----------------------------------------------------------------------------------------------------
public RandomWalkSequence() {
this(MINUS_ONE, ONE);
}
public RandomWalkSequence(BigDecimal minStep, BigDecimal maxStep) {
this(minStep, maxStep, null);
}
public RandomWalkSequence(BigDecimal minStep, BigDecimal maxStep, BigDecimal initial) {
this(minStep, maxStep, initial, DEFAULT_BUFFERED);
}
public RandomWalkSequence(BigDecimal minStep, BigDecimal maxStep, BigDecimal initial, boolean buffered) {
this.minStep = minStep;
this.maxStep = maxStep;
this.initial = initial;
this.buffered = buffered;
}
public void setMinStep(BigDecimal minStep) {
this.minStep = minStep;
}
public void setMaxStep(BigDecimal maxStep) {
this.maxStep = maxStep;
}
public void setInitial(BigDecimal initial) {
this.initial = initial;
}
// Distribution interface implementation ---------------------------------------------------------------------------
public <T extends Number> NonNullGenerator<T> createNumberGenerator(Class<T> numberType, T min, T max, T granularity, boolean unique) {
if (max == null)
max = NumberUtil.maxValue(numberType);
NonNullGenerator<? extends Number> base;
if (BeanUtil.isIntegralNumberType(numberType))
base = createLongGenerator(toLong(min), toLong(max), toLong(granularity), unique);
else
base = createDoubleGenerator(toDouble(min), toDouble(max), toDouble(granularity), unique);
return WrapperFactory.asNonNullNumberGeneratorOfType(numberType, base, min, granularity);
}
@Override
public <T> Generator<T> applyTo(Generator<T> source, boolean unique) {
if (buffered || MathUtil.between(0L, toLong(minStep), toLong(maxStep)))
return super.applyTo(source, unique);
else
return applySkipGenerator(source, unique);
}
private <T> Generator<T> applySkipGenerator(Generator<T> source, boolean unique) {
int minStepI = toInteger(minStep);
if (unique && minStepI <= 0)
throw new ConfigurationError("Cannot generate unique values when minStep=" + minStep);
return new SkipGeneratorProxy<T>(source, minStepI, toInteger(maxStep));
}
// helper methods --------------------------------------------------------------------------------------------------
private <T> NonNullGenerator<? extends Number> createDoubleGenerator(double min, double max, double granularity, boolean unique) {
if (unique && MathUtil.rangeIncludes(0., min, max)) // check if uniqueness requirements can be met
throw new InvalidGeneratorSetupException("Cannot guarantee uniqueness for [min=" + min + ",max=" + max + "]");
return new RandomWalkDoubleGenerator(
toDouble(min), toDouble(max), toDouble(granularity), toDouble(minStep), toDouble(maxStep));
}
private <T> NonNullGenerator<? extends Number> createLongGenerator(long min, long max, long granularity, boolean unique) {
if (unique && MathUtil.rangeIncludes(0, min, max)) // check if uniqueness requirements can be met
throw new InvalidGeneratorSetupException("Cannot guarantee uniqueness for [min=" + min + ",max=" + max + "]");
return new RandomWalkLongGenerator(
min, max, toLong(granularity), toLong(initial(min, max, Long.class)), toLong(minStep), toLong(maxStep));
}
private <T extends Number> T initial(T min, T max, Class<T> numberType) {
if (initial != null)
return NumberToNumberConverter.convert(initial, numberType);
if (minStep.doubleValue() > 0)
return min;
if (maxStep.doubleValue() > 0)
return NumberToNumberConverter.convert((min.doubleValue() + max.doubleValue()) / 2, numberType);
else
return max;
}
}