/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.math.genetics;

/**
 * Stops after a fixed number of generations. Each time
 * {@link #isSatisfied(Population)} is invoked, a generation counter is
 * incremented. Once the counter reaches the configured
 * <code>maxGenerations</code> value, {@link #isSatisfied(Population)} returns
 * true.
 * 
 * @version $Revision:$ $Date:$
 * @since 2.0
 */
public class FixedGenerationCount implements StoppingCondition {
	/** Number of generations that have passed */
	private int numGenerations = 0;

	/** Maximum number of generations (stopping criteria) */
	private final int maxGenerations;

	/**
	 * Create a new FixedGenerationCount instance.
	 * 
	 * @param maxGenerations
	 *            number of generations to evolve
	 */
	public FixedGenerationCount(int maxGenerations) {
		if (maxGenerations <= 0)
			throw new IllegalArgumentException("The number of generations has to be >= 0");
		this.maxGenerations = maxGenerations;
	}

	/**
	 * Determine whether or not the given number of generations have passed.
	 * Increments the number of generations counter if the maximum has not been
	 * reached.
	 * 
	 * @param population
	 *            ignored (no impact on result)
	 * @return <code>true</code> IFF the maximum number of generations has been
	 *         exceeded
	 */
	public boolean isSatisfied(Population population) {
		if (this.numGenerations < this.maxGenerations) {
			numGenerations++;
			return false;
		}
		return true;
	}

	/**
	 * @return the number of generations that have passed
	 */
	public int getNumGenerations() {
		return numGenerations;
	}

}
