131 lines
3.2 KiB
Java
131 lines
3.2 KiB
Java
/*
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* Copyright (C) 2009 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 java.io.Serializable;
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import java.util.Collection;
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import java.util.EnumSet;
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import com.google.common.annotations.GwtCompatible;
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/**
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* Implementation of {@link ImmutableSet} backed by a non-empty
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* {@link java.util.EnumSet}.
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*
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* @author Jared Levy
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*/
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@GwtCompatible(serializable = true, emulated = true)
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@SuppressWarnings("serial") // we're overriding default serialization
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final class ImmutableEnumSet<E extends Enum<E>> extends ImmutableSet<E> {
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static <E extends Enum<E>> ImmutableSet<E> asImmutable(EnumSet<E> set) {
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switch (set.size()) {
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case 0:
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return ImmutableSet.of();
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case 1:
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return ImmutableSet.of(Iterables.getOnlyElement(set));
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default:
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return new ImmutableEnumSet<E>(set);
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}
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}
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/*
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* Notes on EnumSet and <E extends Enum<E>>:
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*
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* This class isn't an arbitrary ForwardingImmutableSet because we need to know
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* that calling {@code clone()} during deserialization will return an object
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* that no one else has a reference to, allowing us to guarantee immutability.
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* Hence, we support only {@link EnumSet}.
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*/
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private final transient EnumSet<E> delegate;
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private ImmutableEnumSet(EnumSet<E> delegate) {
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this.delegate = delegate;
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}
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@Override
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boolean isPartialView() {
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return false;
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}
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@Override
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public UnmodifiableIterator<E> iterator() {
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return Iterators.unmodifiableIterator(delegate.iterator());
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}
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@Override
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public int size() {
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return delegate.size();
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}
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@Override
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public boolean contains(Object object) {
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return delegate.contains(object);
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}
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@Override
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public boolean containsAll(Collection<?> collection) {
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return delegate.containsAll(collection);
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}
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@Override
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public boolean isEmpty() {
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return delegate.isEmpty();
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}
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@Override
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public boolean equals(Object object) {
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return object == this || delegate.equals(object);
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}
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private transient int hashCode;
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@Override
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public int hashCode() {
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int result = hashCode;
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return (result == 0) ? hashCode = delegate.hashCode() : result;
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}
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@Override
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public String toString() {
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return delegate.toString();
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}
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// All callers of the constructor are restricted to <E extends Enum<E>>.
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@Override
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Object writeReplace() {
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return new EnumSerializedForm<E>(delegate);
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}
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/*
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* This class is used to serialize ImmutableEnumSet instances.
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*/
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private static class EnumSerializedForm<E extends Enum<E>> implements Serializable {
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final EnumSet<E> delegate;
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EnumSerializedForm(EnumSet<E> delegate) {
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this.delegate = delegate;
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}
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Object readResolve() {
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// EJ2 #76: Write readObject() methods defensively.
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return new ImmutableEnumSet<E>(delegate.clone());
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}
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private static final long serialVersionUID = 0;
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}
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}
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