CloneLibrary.java

/* Copyright (c) 2001 - 2007 TOPP - www.openplans.org.  All rights reserved.
 * This code is licensed under the GPL 2.0 license, availible at the root
 * application directory.
 */
package org.vfny.geoserver.global.dto;

import com.vividsolutions.jts.geom.Envelope;
import java.lang.reflect.Constructor;
import java.util.Iterator;
import java.util.List;
import java.util.Map;


/**
 * CloneLibrary purpose is used to try and Set up a Deep Copy for DTO objets.
 *
 * <p>
 * Static Library class for cloning complex structures independant of their
 * contents.
 * </p>
 *
 * <p>
 * Jody here - this is much more accessable when presented to the user as new
 * Type( Type ) idiom. Java clone is messed up, I have seen several projects
 * move to a copy() method or the above idom.
 * </p>
 *
 * <p>
 * For the here and now we can use the above Idom. This will even work with all
 * of our lists and Maps since we are only ever using Strings (imutable) in
 * them.
 * </p>
 *
 * @author dzwiers, Refractions Research, Inc.
 * @version $Id$
 */
public final class CloneLibrary {
    /**
     * clone purpose.
     *
     * <p>
     * Clones a List so that it matches the requirements that the returned
     * object  would be equal to the source.
     * </p>
     *
     * @param source The list to be cloned.
     *
     * @return An exact clone of the list.
     *
     * @throws CloneNotSupportedException
     *
     * @see java.lang.Object#clone()
     * @see java.util.List
     */
    public static List clone(List source) throws CloneNotSupportedException {
        if (source == null) {
            return null;
        }

        List result;

        //to get an exact instance, need to match sub-types for .equals method
        try {
            Class c = source.getClass();
            Constructor ct = c.getConstructor(new Class[0]);
            result = (List) ct.newInstance(new Object[0]);
        } catch (Exception e) {
            throw new CloneNotSupportedException();
        }

        Object[] lst = source.toArray();

        for (int i = 0; i < lst.length; i++) {
            result.add(i, clone(lst[i]));
        }

        return result;
    }

    /**
     * clone purpose.
     *
     * <p>
     * Clones a Map so that it matches the requirements that the returned
     * object  would be equal to the source.
     * </p>
     *
     * @param source The Map to be cloned.
     *
     * @return An exact clone of the list.
     *
     * @throws CloneNotSupportedException
     *
     * @see java.lang.Object#clone()
     * @see java.util.Map
     */
    public static Map clone(Map source) throws CloneNotSupportedException {
        if (source == null) {
            return null;
        }

        Map result;

        //to get an exact instance, need to match sub-types for .equals method
        try {
            Class c = source.getClass();
            Constructor ct = c.getConstructor(new Class[0]);
            result = (Map) ct.newInstance(new Object[0]);
        } catch (Exception e) {
            throw new CloneNotSupportedException();
        }

        //result.putAll(source);
        Iterator keyIter = source.keySet().iterator();

        while (keyIter.hasNext()) {
            Object key = keyIter.next();
            result.put(key, clone(source.get(key)));
        }

        return result;
    }

    /**
     * clone purpose.
     *
     * <p>
     * Clones a Envelope so that it matches the requirements that the returned
     * object  would be equal to the source.
     * </p>
     *
     * @param e The Envelope to be cloned.
     *
     * @return An exact clone of the list.
     *
     * @see java.lang.Object#clone()
     * @see com.vividsolutions.jts.geom.Envelope
     */
    public static Envelope clone(Envelope e) {
        if(e == null)
            return null;
        Envelope result = new Envelope(e);

        return result;
    }

    /**
     * clone purpose.
     *
     * <p>
     * used to check class type and clone it.
     * </p>
     *
     * @param ds the DataStructure to clone.
     *
     * @return a clone of the parameter
     */
    private static Object clone(DataTransferObject ds) {
        return ds.clone();
    }

    /**
     * Clone a string array
     *
     * @param array DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    public static String[] clone(String[] array) {
        String[] copy = new String[array.length];
        System.arraycopy(array, 0, copy, 0, array.length);

        return copy;
    }

    /**
     * clone purpose.
     *
     * <p>
     * to make the compiler happy, should never be here.
     * </p>
     *
     * @param obj the parameter to return, does nothing.
     *
     * @return returns the parameter
     */
    private static Object clone(Object obj) {
        return obj;
    }
}