107 lines
3.4 KiB
Java
107 lines
3.4 KiB
Java
/*
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* Copyright (C) 2007 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.common.collect;
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import static com.google.common.base.Preconditions.checkNotNull;
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import java.util.Collection;
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import java.util.Set;
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import javax.annotation.Nullable;
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import com.google.common.annotations.GwtCompatible;
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/**
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* A set which forwards all its method calls to another set. Subclasses should
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* override one or more methods to modify the behavior of the backing set as
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* desired per the
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* <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator
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* pattern</a>.
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*
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* <p>
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* <b>Warning:</b> The methods of {@code ForwardingSet} forward
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* <b>indiscriminately</b> to the methods of the delegate. For example,
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* overriding {@link #add} alone <b>will not</b> change the behavior of
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* {@link #addAll}, which can lead to unexpected behavior. In this case, you
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* should override {@code addAll} as well, either providing your own
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* implementation, or delegating to the provided {@code standardAddAll} method.
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*
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* <p>
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* The {@code standard} methods are not guaranteed to be thread-safe, even when
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* all of the methods that they depend on are thread-safe.
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*
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* @author Kevin Bourrillion
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* @author Louis Wasserman
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* @since 2.0 (imported from Google Collections Library)
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*/
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@GwtCompatible
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public abstract class ForwardingSet<E> extends ForwardingCollection<E> implements Set<E> {
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// TODO(user): identify places where thread safety is actually lost
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/** Constructor for use by subclasses. */
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protected ForwardingSet() {
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}
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@Override
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protected abstract Set<E> delegate();
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@Override
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public boolean equals(@Nullable Object object) {
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return object == this || delegate().equals(object);
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}
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@Override
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public int hashCode() {
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return delegate().hashCode();
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}
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/**
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* A sensible definition of {@link #removeAll} in terms of {@link #iterator} and
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* {@link #remove}. If you override {@code iterator} or {@code remove}, you may
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* wish to override {@link #removeAll} to forward to this implementation.
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*
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* @since 7.0 (this version overrides the {@code ForwardingCollection} version
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* as of 12.0)
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*/
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@Override
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protected boolean standardRemoveAll(Collection<?> collection) {
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return Sets.removeAllImpl(this, checkNotNull(collection)); // for GWT
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}
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/**
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* A sensible definition of {@link #equals} in terms of {@link #size} and
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* {@link #containsAll}. If you override either of those methods, you may wish
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* to override {@link #equals} to forward to this implementation.
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*
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* @since 7.0
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*/
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protected boolean standardEquals(@Nullable Object object) {
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return Sets.equalsImpl(this, object);
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}
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/**
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* A sensible definition of {@link #hashCode} in terms of {@link #iterator}. If
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* you override {@link #iterator}, you may wish to override {@link #equals} to
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* forward to this implementation.
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*
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* @since 7.0
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*/
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protected int standardHashCode() {
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return Sets.hashCodeImpl(this);
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}
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}
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