/*
 * Copyright 2007-2013
 * Licensed under GNU Lesser General Public License
 * 
 * This file is part of EpochX
 * 
 * EpochX 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 of the License, or
 * (at your option) any later version.
 * 
 * EpochX 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with EpochX. If not, see <http://www.gnu.org/licenses/>.
 * 
 * The latest version is available from: http://www.epochx.org
 */

package org.epochx;

import org.epochx.Config.ConfigKey;

/**
 * Implementations of <code>FitnessEvaluator</code> are components that are
 * responsible for assigning fitnesses to individuals in a population. Typically
 * this will be performed by evaluating the quality of each individual against
 * problem specific requirements.
 */
public class FitnessEvaluator extends ProxyComponent<FitnessFunction> {

	/**
	 * The key for setting and retrieving the <code>FitnessFunction</code> used
	 * by this component.
	 */
	public static final ConfigKey<FitnessFunction> FUNCTION = new ConfigKey<FitnessFunction>();

	/**
	 * Constructs a <code>FitnessEvaluator</code>.
	 */
	public FitnessEvaluator() {
		super(FUNCTION);
	}

	/**
	 * Delegates the evaluation of the population to the
	 * <code>FitnessFunction</code> object.
	 */
	@Override
	public Population process(Population population) {
		if (handler == null) {
			throw new IllegalStateException("The fitness function has not been set.");
		}

		handler.evaluate(population);
		return population;
	}

}