11d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert/* 21d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * Copyright (C) 2007 The Guava Authors 31d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 41d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * Licensed under the Apache License, Version 2.0 (the "License"); 51d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * you may not use this file except in compliance with the License. 61d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * You may obtain a copy of the License at 71d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 81d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * http://www.apache.org/licenses/LICENSE-2.0 91d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 101d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * Unless required by applicable law or agreed to in writing, software 111d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * distributed under the License is distributed on an "AS IS" BASIS, 121d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 131d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * See the License for the specific language governing permissions and 141d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * limitations under the License. 151d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert */ 161d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 171d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringertpackage com.google.common.collect; 181d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 191d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringertimport com.google.common.annotations.Beta; 201d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringertimport com.google.common.annotations.GwtCompatible; 211d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 221d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringertimport java.util.Set; 231d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 241d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringertimport javax.annotation.Nullable; 251d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 261d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert/** 271d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * A set which forwards all its method calls to another set. Subclasses should 281d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * override one or more methods to modify the behavior of the backing set as 291d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * desired per the <a 301d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>. 311d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 321d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * <p><b>Warning:</b> The methods of {@code ForwardingSet} forward 331d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * <b>indiscriminately</b> to the methods of the delegate. For example, 341d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * overriding {@link #add} alone <b>will not</b> change the behavior of {@link 351d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * #addAll}, which can lead to unexpected behavior. In this case, you should 361d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * override {@code addAll} as well, either providing your own implementation, or 371d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * delegating to the provided {@code standardAddAll} method. 381d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 391d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * <p>The {@code standard} methods are not guaranteed to be thread-safe, even 401d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * when all of the methods that they depend on are thread-safe. 411d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 421d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * @author Kevin Bourrillion 431d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * @author Louis Wasserman 441d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * @since 2.0 (imported from Google Collections Library) 451d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert */ 461d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert@GwtCompatible 471d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringertpublic abstract class ForwardingSet<E> extends ForwardingCollection<E> 481d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert implements Set<E> { 491d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert // TODO(user): identify places where thread safety is actually lost 501d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 511d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert /** Constructor for use by subclasses. */ 521d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert protected ForwardingSet() {} 531d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 541d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert @Override protected abstract Set<E> delegate(); 551d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 561d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert @Override public boolean equals(@Nullable Object object) { 571d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert return object == this || delegate().equals(object); 581d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert } 591d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 601d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert @Override public int hashCode() { 611d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert return delegate().hashCode(); 621d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert } 631d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 641d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert /** 651d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * A sensible definition of {@link #equals} in terms of {@link #size} and 661d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * {@link #containsAll}. If you override either of those methods, you may wish 671d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * to override {@link #equals} to forward to this implementation. 681d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 691d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * @since 7.0 701d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert */ 711d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert @Beta protected boolean standardEquals(@Nullable Object object) { 721d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert return Sets.equalsImpl(this, object); 731d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert } 741d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert 751d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert /** 761d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * A sensible definition of {@link #hashCode} in terms of {@link #iterator}. 771d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * If you override {@link #iterator}, you may wish to override {@link #equals} 781d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * to forward to this implementation. 791d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * 801d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert * @since 7.0 811d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert */ 821d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert @Beta protected int standardHashCode() { 831d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert return Sets.hashCodeImpl(this); 841d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert } 851d580d0f6ee4f21eb309ba7b509d2c6d671c4044Bjorn Bringert} 86