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/*
* 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 javax.annotation.CheckForNull;
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 decorator pattern.
*
* Warning: The methods of {@code ForwardingSet} forward indiscriminately to the
* methods of the delegate. For example, overriding {@link #add} alone will not 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.
*
*
{@code default} method warning: This class does not forward calls to {@code
* default} methods. Instead, it inherits their default implementations. When those implementations
* invoke methods, they invoke methods on the {@code ForwardingSet}.
*
*
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
@ElementTypesAreNonnullByDefault
public abstract class ForwardingSet extends ForwardingCollection
implements Set {
// TODO(lowasser): identify places where thread safety is actually lost
/** Constructor for use by subclasses. */
protected ForwardingSet() {}
@Override
protected abstract Set delegate();
@Override
public boolean equals(@CheckForNull 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(@CheckForNull 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);
}
}