/*
* Copyright (c) 2014, grossmann
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the jo-widgets.org nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL jo-widgets.org BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
package org.jowidgets.util.collection;
import java.util.Arrays;
import java.util.Iterator;
import org.jowidgets.util.Assert;
import org.jowidgets.util.CollectionUtils;
final class ObserverSetMemoryStrategyImpl<OBSERVER_TYPE> implements IObserverSet<OBSERVER_TYPE> {
private OBSERVER_TYPE[] listeners;
@Override
public Iterator<OBSERVER_TYPE> iterator() {
if (listeners == null) {
return CollectionUtils.unmodifiableEmptyIterator();
}
else {
return CollectionUtils.unmodifiableIterator(Arrays.asList(listeners).iterator());
}
}
@SuppressWarnings("unchecked")
@Override
public void add(final OBSERVER_TYPE observer) {
Assert.paramNotNull(observer, "observer");
if (listeners == null) {
listeners = (OBSERVER_TYPE[]) new Object[1];
listeners[0] = observer;
}
else {
if (indexOf(observer) == -1) {//only add if not already done
final Object[] oldListeners = listeners;
listeners = (OBSERVER_TYPE[]) new Object[oldListeners.length + 1];
System.arraycopy(oldListeners, 0, listeners, 0, oldListeners.length);
listeners[listeners.length - 1] = observer;
}
}
}
@SuppressWarnings("unchecked")
@Override
public boolean remove(final OBSERVER_TYPE observer) {
Assert.paramNotNull(observer, "observer");
if (listeners != null) {
//listeners.length is at least 1
if (listeners.length == 1) {
if (listeners[0].equals(observer)) {
listeners = null;
return true;
}
}
else {//listeners.length > 1
final int removeIndex = indexOf(observer);
if (removeIndex != -1) {
final Object[] oldListeners = listeners;
listeners = (OBSERVER_TYPE[]) new Object[oldListeners.length - 1];
if (removeIndex == 0) {//first removed
System.arraycopy(oldListeners, 1, listeners, 0, listeners.length);
}
else if (removeIndex == oldListeners.length - 1) {//last removed
System.arraycopy(oldListeners, 0, listeners, 0, listeners.length);
}
else {//removed in the middle
final int indexAfter = removeIndex + 1;
System.arraycopy(oldListeners, 0, listeners, 0, removeIndex);
System.arraycopy(oldListeners, indexAfter, listeners, removeIndex, listeners.length - removeIndex);
}
return true;
}
}
}
return false;
}
private int indexOf(final OBSERVER_TYPE observer) {
if (listeners != null) {
for (int index = 0; index < listeners.length; index++) {
//by contract there are no null elements so this works
if (listeners[index].equals(observer)) {
return index;
}
}
}
return -1;
}
@Override
public void clear() {
listeners = null;
}
}