| /* |
| * Copyright (C) 2007 The Guava Authors |
| * |
| * Licensed 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 com.google.common.collect; |
| |
| import static com.google.common.base.Preconditions.checkNotNull; |
| |
| import com.google.common.annotations.GwtCompatible; |
| import java.util.Collection; |
| import java.util.Set; |
| import org.checkerframework.checker.nullness.qual.Nullable; |
| |
| /** |
| * A set which forwards all its method calls to another set. Subclasses should override one or more |
| * methods to modify the behavior of the backing set as desired per the <a |
| * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>. |
| * |
| * <p><b>Warning:</b> The methods of {@code ForwardingSet} forward <b>indiscriminately</b> to the |
| * methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change the |
| * behavior of {@link #addAll}, which can lead to unexpected behavior. In this case, you should |
| * override {@code addAll} as well, either providing your own implementation, or delegating to the |
| * provided {@code standardAddAll} method. |
| * |
| * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code |
| * default} methods. Instead, it inherits their default implementations. When those implementations |
| * invoke methods, they invoke methods on the {@code ForwardingSet}. |
| * |
| * <p>The {@code standard} methods are not guaranteed to be thread-safe, even when all of the |
| * methods that they depend on are thread-safe. |
| * |
| * @author Kevin Bourrillion |
| * @author Louis Wasserman |
| * @since 2.0 |
| */ |
| @GwtCompatible |
| public abstract class ForwardingSet<E> extends ForwardingCollection<E> implements Set<E> { |
| // TODO(lowasser): identify places where thread safety is actually lost |
| |
| /** Constructor for use by subclasses. */ |
| protected ForwardingSet() {} |
| |
| @Override |
| protected abstract Set<E> delegate(); |
| |
| @Override |
| public boolean equals(@Nullable Object object) { |
| return object == this || delegate().equals(object); |
| } |
| |
| @Override |
| public int hashCode() { |
| return delegate().hashCode(); |
| } |
| |
| /** |
| * A sensible definition of {@link #removeAll} in terms of {@link #iterator} and {@link #remove}. |
| * If you override {@code iterator} or {@code remove}, you may wish to override {@link #removeAll} |
| * to forward to this implementation. |
| * |
| * @since 7.0 (this version overrides the {@code ForwardingCollection} version as of 12.0) |
| */ |
| @Override |
| protected boolean standardRemoveAll(Collection<?> collection) { |
| return Sets.removeAllImpl(this, checkNotNull(collection)); // for GWT |
| } |
| |
| /** |
| * A sensible definition of {@link #equals} in terms of {@link #size} and {@link #containsAll}. If |
| * you override either of those methods, you may wish to override {@link #equals} to forward to |
| * this implementation. |
| * |
| * @since 7.0 |
| */ |
| protected boolean standardEquals(@Nullable Object object) { |
| return Sets.equalsImpl(this, object); |
| } |
| |
| /** |
| * A sensible definition of {@link #hashCode} in terms of {@link #iterator}. If you override |
| * {@link #iterator}, you may wish to override {@link #equals} to forward to this implementation. |
| * |
| * @since 7.0 |
| */ |
| protected int standardHashCode() { |
| return Sets.hashCodeImpl(this); |
| } |
| } |