org.evosuite.ga.TournamentChromosomeFactory Maven / Gradle / Ivy

Go to download
/**
 * Copyright (C) 2010-2018 Gordon Fraser, Andrea Arcuri and EvoSuite
 * contributors
 *
 * This file is part of EvoSuite.
 *
 * EvoSuite is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3.0 of the License, or
 * (at your option) any later version.
 *
 * EvoSuite is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with EvoSuite. If not, see .
 */
/**
 * 
 */
package org.evosuite.ga;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 
 * TournamentChromosomeFactory class.
 * 
 * 
 * @author Gordon Fraser
 * @param 
 */
public class TournamentChromosomeFactory implements
        ChromosomeFactory {

	private static final long serialVersionUID = -2493386206236363431L;

	private static final Logger logger = LoggerFactory.getLogger(TournamentChromosomeFactory.class);

	private final FitnessFunction fitnessFunction;

	private final ChromosomeFactory factory;

	private final int tournamentSize = 10;

	/**
	 * 
	 * Constructor for TournamentChromosomeFactory.
	 * 
	 * 
	 * @param fitness
	 *            a {@link org.evosuite.ga.FitnessFunction} object.
	 * @param factory
	 *            a {@link org.evosuite.ga.ChromosomeFactory} object.
	 * @param 
	 *            a T object.
	 */
	public TournamentChromosomeFactory(FitnessFunction fitness,
	        ChromosomeFactory factory) {
		this.fitnessFunction = fitness;
		this.factory = factory;
	}

	/**
	 * {@inheritDoc}
	 * 
	 * This factory produces tournamentSize individuals, and returns the
	 * best one
	 */
	@Override
	public T getChromosome() {
		T bestIndividual = null;
		logger.debug("Starting random generation");
		for (int i = 0; i < tournamentSize; i++) {
			T candidate = factory.getChromosome();
			fitnessFunction.getFitness(candidate);
			if (bestIndividual == null) {
				bestIndividual = candidate;
			} else if (candidate.compareTo(bestIndividual) <= 0) {
				logger.debug("Old individual has fitness " + bestIndividual.getFitness(this.fitnessFunction)
				        + ", replacing with fitness " + candidate.getFitness(this.fitnessFunction));
				bestIndividual = candidate;
			}
		}
		if (bestIndividual != null)
			logger.debug("Resulting fitness: " + bestIndividual.getFitness(this.fitnessFunction));

		assert (bestIndividual != null);

		return (T) bestIndividual;
	}
}