/*
* This file is part of NucleusFramework for Bukkit, licensed under the MIT License (MIT).
*
* Copyright (c) JCThePants (www.jcwhatever.com)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.jcwhatever.nucleus.collections.wrap;
import com.jcwhatever.nucleus.utils.CollectionUtils;
import com.jcwhatever.nucleus.utils.PreCon;
import com.jcwhatever.nucleus.utils.validate.IValidator;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.locks.ReadWriteLock;
/**
* An abstract implementation of a {@link Collection} wrapper. The wrapper is
* optionally synchronized via a sync object or {@link ReadWriteLock} passed
* into the constructor using a {@link SyncStrategy}.
*
* <p>The actual collection is provided to the abstract implementation by
* overriding and returning it from the {@link #collection} method.</p>
*
* <p>In order to make using the wrapper as an extension of a collection easier,
* several protected methods are provided for optional override.
* See {@link #onPreAdd}, {@link #onAdded}, {@link #onPreRemove}, {@link #onRemoved},
* {@link #onPreClear}, {@link #onClear}</p>
*/
public abstract class CollectionWrapper<E> implements Collection<E> {
protected final Object _sync;
protected final ReadWriteLock _lock;
protected final SyncStrategy _strategy;
/**
* Constructor.
*/
public CollectionWrapper() {
this(SyncStrategy.NONE);
}
/**
* Constructor.
*
* @param strategy The synchronization strategy to use.
*/
public CollectionWrapper(SyncStrategy strategy) {
PreCon.notNull(strategy);
_sync = strategy.getSync(this);
_strategy = new SyncStrategy(_sync);
_lock = _sync instanceof ReadWriteLock
? (ReadWriteLock) _sync
: null;
}
/**
* Invoked before an element is added.
*
* <p>Not guaranteed to be called from a synchronized block.</p>
*
* <p>Intended to be optionally overridden by implementation.</p>
*
* @param e The element that will be added.
*
* @return True to allow, false to deny.
*/
protected boolean onPreAdd(E e) { return true; }
/**
* Invoked after an element is added.
*
* <p>Not guaranteed to be called from a synchronized block.</p>
*
* <p>Intended to be optionally overridden by implementation.</p>
*
* @param e The element that was added.
*/
protected void onAdded(E e) {}
/**
* Invoked before an element is removed except when
* {@link #clear} is invoked.
*
* <p>Not guaranteed to be called from a synchronized block.</p>
*
* <p>Intended to be optionally overridden by implementation.</p>
*
* @param o The object that will match the item to removed.
*
* @return True to allow the removal, false to deny.
*/
protected boolean onPreRemove(Object o) { return true; }
/**
* Invoked after an element is removed except when
* {@link #clear} is invoked.
*
* <p>Not guaranteed to be called from a synchronized block.</p>
*
* <p>Intended to be optionally overridden by implementation.</p>
*
* @param o The removed object.
*/
protected void onRemoved(Object o) {}
/**
* Invoked before the collection is cleared.
*
* <p>Not guaranteed to be called from a synchronized block.</p>
*
* <p>Intended to be optionally overridden by implementation.</p>
*/
protected void onPreClear() {}
/**
* Invoked after {@link #clear} is invoked.
*
* <p>Not guaranteed to be called from a synchronized block.</p>
*
* <p>Intended to be optionally overridden by implementation.</p>
*
* @param values The values that were cleared from the collection.
*/
protected void onClear(Collection<E> values) {}
/**
* Invoked from a synchronized block to get the collection.
*/
protected abstract Collection<E> collection();
@Override
public int size() {
if (_lock != null) {
_lock.readLock().lock();
try {
return collection().size();
}
finally {
_lock.readLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
return collection().size();
}
}
else {
return collection().size();
}
}
@Override
public boolean isEmpty() {
if (_lock != null) {
_lock.readLock().lock();
try {
return collection().isEmpty();
}
finally {
_lock.readLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
return collection().isEmpty();
}
}
else {
return collection().isEmpty();
}
}
@Override
public boolean contains(Object o) {
if (_lock != null) {
_lock.readLock().lock();
try {
return collection().contains(o);
}
finally {
_lock.readLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
return collection().contains(o);
}
}
else {
return collection().contains(o);
}
}
@Override
public Iterator<E> iterator() {
return new Itr();
}
@Override
public Object[] toArray() {
if (_lock != null) {
_lock.readLock().lock();
try {
return collection().toArray();
}
finally {
_lock.readLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
return collection().toArray();
}
}
else {
return collection().toArray();
}
}
@Override
public <T> T[] toArray(T[] a) {
if (_lock != null) {
_lock.readLock().lock();
try {
//noinspection SuspiciousToArrayCall
return collection().toArray(a);
}
finally {
_lock.readLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
//noinspection SuspiciousToArrayCall
return collection().toArray(a);
}
}
else {
//noinspection SuspiciousToArrayCall
return collection().toArray(a);
}
}
@Override
public boolean add(E e) {
PreCon.notNull(e);
if (!onPreAdd(e))
return false;
boolean isAdded;
if (_lock != null) {
_lock.writeLock().lock();
try {
isAdded = collection().add(e);
}
finally {
_lock.writeLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
isAdded = collection().add(e);
}
}
else {
isAdded = collection().add(e);
}
if (isAdded)
onAdded(e);
return isAdded;
}
@Override
public boolean remove(Object o) {
if (!onPreRemove(o))
return false;
boolean isRemoved;
if (_lock != null) {
_lock.writeLock().lock();
try {
isRemoved = collection().remove(o);
}
finally {
_lock.writeLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
isRemoved = collection().remove(o);
}
}
else {
isRemoved = collection().remove(o);
}
if (isRemoved) {
onRemoved(o);
}
return isRemoved;
}
@Override
public boolean containsAll(Collection<?> c) {
PreCon.notNull(c);
if (_lock != null) {
_lock.readLock().lock();
try {
return collection().containsAll(c);
}
finally {
_lock.readLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
return collection().containsAll(c);
}
}
else {
return collection().containsAll(c);
}
}
@Override
public boolean addAll(Collection<? extends E> c) {
PreCon.notNull(c);
if (_lock != null) {
_lock.writeLock().lock();
try {
return addAllSource(c);
}
finally {
_lock.writeLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
return addAllSource(c);
}
}
else {
return addAllSource(c);
}
}
private boolean addAllSource(Collection<? extends E> c) {
boolean isChanged = false;
for (E e : c) {
isChanged = add(e) || isChanged;
}
return isChanged;
}
@Override
public boolean removeAll(Collection<?> c) {
PreCon.notNull(c);
if (_lock != null) {
_lock.writeLock().lock();
try {
return removeAllSource(c);
}
finally {
_lock.writeLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
return removeAllSource(c);
}
}
else {
return removeAllSource(c);
}
}
private boolean removeAllSource(Collection<?> c) {
boolean isChanged = false;
for (Object obj : c) {
isChanged = remove(obj) || isChanged;
}
return isChanged;
}
@Override
public boolean retainAll(final Collection<?> c) {
PreCon.notNull(c);
List<E> removed;
if (_lock != null) {
_lock.writeLock().lock();
try {
removed = retainAllSource(c);
}
finally {
_lock.writeLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
removed = retainAllSource(c);
}
}
else {
removed = retainAllSource(c);
}
for (E agent : removed) {
onRemoved(agent);
}
return !removed.isEmpty();
}
private List<E> retainAllSource(final Collection<?> c) {
return CollectionUtils.retainAll(collection(), new IValidator<E>() {
@Override
public boolean isValid(E element) {
return c.contains(element) && onPreRemove(element);
}
});
}
@Override
public void clear() {
onPreClear();
Collection<E> values;
if (_lock != null) {
_lock.writeLock().lock();
try {
values = clearSource();
}
finally {
_lock.writeLock().unlock();
}
}
else if (_sync != null) {
synchronized (_sync) {
values = clearSource();
}
}
else {
values = clearSource();
}
onClear(values);
}
private Collection<E> clearSource() {
Collection<E> values = new ArrayList<E>(collection());
collection().clear();
return values;
}
private final class Itr extends IteratorWrapper<E> {
Itr() {
super(CollectionWrapper.this._strategy);
}
Iterator<E> iterator = collection().iterator();
@Override
protected boolean onRemove(E element) {
if (!CollectionWrapper.this.onPreRemove(element))
return false;
CollectionWrapper.this.onRemoved(element);
return true;
}
@Override
protected Iterator<E> iterator() {
return iterator;
}
}
}