85 lines
1.9 KiB
Java
85 lines
1.9 KiB
Java
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/*
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* Copyright (C) 2008 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 javax.annotation.Nullable;
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import com.google.common.annotations.GwtCompatible;
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/**
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* Bimap with no mappings.
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*
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* @author Jared Levy
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*/
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@GwtCompatible(emulated = true)
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@SuppressWarnings("serial") // uses writeReplace(), not default serialization
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final class EmptyImmutableBiMap extends ImmutableBiMap<Object, Object> {
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static final EmptyImmutableBiMap INSTANCE = new EmptyImmutableBiMap();
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private EmptyImmutableBiMap() {
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}
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@Override
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public ImmutableBiMap<Object, Object> inverse() {
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return this;
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}
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@Override
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public int size() {
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return 0;
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}
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@Override
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public boolean isEmpty() {
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return true;
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}
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@Override
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public Object get(@Nullable Object key) {
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return null;
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}
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@Override
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public ImmutableSet<Entry<Object, Object>> entrySet() {
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return ImmutableSet.of();
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}
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@Override
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ImmutableSet<Entry<Object, Object>> createEntrySet() {
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throw new AssertionError("should never be called");
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}
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@Override
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public ImmutableSetMultimap<Object, Object> asMultimap() {
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return ImmutableSetMultimap.of();
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}
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@Override
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public ImmutableSet<Object> keySet() {
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return ImmutableSet.of();
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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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Object readResolve() {
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return INSTANCE; // preserve singleton property
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}
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}
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