/*
 * 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.complex;

import java.io.Serializable;

import org.apache.commons.math.Field;

/**
 * Representation of the complex numbers field.
 * <p>
 * This class is a singleton.
 * </p>
 * 
 * @see Complex
 * @version $Revision$ $Date$
 * @since 2.0
 */
public class ComplexField implements Field<Complex>, Serializable {
	// TODO: Add Serializable documentation
	// TODO: Check Serializable implementation

	/** Serializable version identifier. */
	private static final long serialVersionUID = -6130362688700788798L;

	/**
	 * Private constructor for the singleton.
	 */
	private ComplexField() {
	}

	/**
	 * Get the unique instance.
	 * 
	 * @return the unique instance
	 */
	public static ComplexField getInstance() {
		return LazyHolder.INSTANCE;
	}

	/** {@inheritDoc} */
	public Complex getOne() {
		return Complex.ONE;
	}

	/** {@inheritDoc} */
	public Complex getZero() {
		return Complex.ZERO;
	}

	/**
	 * Holder for the instance.
	 * <p>
	 * We use here the Initialization On Demand Holder Idiom.
	 * </p>
	 */
	private static class LazyHolder {
		/** Cached field instance. */
		private static final ComplexField INSTANCE = new ComplexField();
	}

}
