001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.math3.geometry.spherical.oned;
019
020import java.io.Serializable;
021
022import org.apache.commons.math3.exception.MathUnsupportedOperationException;
023import org.apache.commons.math3.exception.util.LocalizedFormats;
024import org.apache.commons.math3.geometry.Space;
025
026/**
027 * This class implements a one-dimensional sphere (i.e. a circle).
028 * <p>
029 * We use here the topologists definition of the 1-sphere (see
030 * <a href="http://mathworld.wolfram.com/Sphere.html">Sphere</a> on
031 * MathWorld), i.e. the 1-sphere is the one-dimensional closed curve
032 * defined in 2D as x<sup>2</sup>+y<sup>2</sup>=1.
033 * </p>
034 * @since 3.3
035 */
036public class Sphere1D implements Serializable, Space {
037
038    /** Serializable version identifier. */
039    private static final long serialVersionUID = 20131218L;
040
041    /** Private constructor for the singleton.
042     */
043    private Sphere1D() {
044    }
045
046    /** Get the unique instance.
047     * @return the unique instance
048     */
049    public static Sphere1D getInstance() {
050        return LazyHolder.INSTANCE;
051    }
052
053    /** {@inheritDoc} */
054    public int getDimension() {
055        return 1;
056    }
057
058    /** {@inheritDoc}
059     * <p>
060     * As the 1-dimension sphere does not have proper sub-spaces,
061     * this method always throws a {@link NoSubSpaceException}
062     * </p>
063     * @return nothing
064     * @throws NoSubSpaceException in all cases
065     */
066    public Space getSubSpace() throws NoSubSpaceException {
067        throw new NoSubSpaceException();
068    }
069
070    // CHECKSTYLE: stop HideUtilityClassConstructor
071    /** Holder for the instance.
072     * <p>We use here the Initialization On Demand Holder Idiom.</p>
073     */
074    private static class LazyHolder {
075        /** Cached field instance. */
076        private static final Sphere1D INSTANCE = new Sphere1D();
077    }
078    // CHECKSTYLE: resume HideUtilityClassConstructor
079
080    /** Handle deserialization of the singleton.
081     * @return the singleton instance
082     */
083    private Object readResolve() {
084        // return the singleton instance
085        return LazyHolder.INSTANCE;
086    }
087
088    /** Specialized exception for inexistent sub-space.
089     * <p>
090     * This exception is thrown when attempting to get the sub-space of a one-dimensional space
091     * </p>
092     */
093    public static class NoSubSpaceException extends MathUnsupportedOperationException {
094
095        /** Serializable UID. */
096        private static final long serialVersionUID = 20140225L;
097
098        /** Simple constructor.
099         */
100        public NoSubSpaceException() {
101            super(LocalizedFormats.NOT_SUPPORTED_IN_DIMENSION_N, 1);
102        }
103
104    }
105
106}