435 lines
15 KiB
Java
435 lines
15 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 static com.google.common.base.Preconditions.checkState;
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import static com.google.common.collect.CollectPreconditions.checkNonnegative;
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import com.google.common.annotations.Beta;
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import com.google.common.annotations.GwtCompatible;
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import com.google.common.annotations.VisibleForTesting;
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import java.util.Arrays;
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import java.util.Comparator;
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import java.util.Map;
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import java.util.function.Function;
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import java.util.stream.Collector;
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import java.util.stream.Collectors;
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/**
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* A {@link BiMap} whose contents will never change, with many other important properties detailed
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* at {@link ImmutableCollection}.
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*
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* @author Jared Levy
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* @since 2.0
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*/
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@GwtCompatible(serializable = true, emulated = true)
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public abstract class ImmutableBiMap<K, V> extends ImmutableBiMapFauxverideShim<K, V>
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implements BiMap<K, V> {
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/**
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* Returns a {@link Collector} that accumulates elements into an {@code ImmutableBiMap} whose keys
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* and values are the result of applying the provided mapping functions to the input elements.
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* Entries appear in the result {@code ImmutableBiMap} in encounter order.
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*
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* <p>If the mapped keys or values contain duplicates (according to {@link Object#equals(Object)},
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* an {@code IllegalArgumentException} is thrown when the collection operation is performed. (This
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* differs from the {@code Collector} returned by {@link Collectors#toMap(Function, Function)},
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* which throws an {@code IllegalStateException}.)
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*
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* @since 21.0
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*/
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public static <T, K, V> Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap(
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Function<? super T, ? extends K> keyFunction,
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Function<? super T, ? extends V> valueFunction) {
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return CollectCollectors.toImmutableBiMap(keyFunction, valueFunction);
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}
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/** Returns the empty bimap. */
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// Casting to any type is safe because the set will never hold any elements.
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@SuppressWarnings("unchecked")
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public static <K, V> ImmutableBiMap<K, V> of() {
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return (ImmutableBiMap<K, V>) RegularImmutableBiMap.EMPTY;
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}
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/** Returns an immutable bimap containing a single entry. */
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public static <K, V> ImmutableBiMap<K, V> of(K k1, V v1) {
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return new SingletonImmutableBiMap<>(k1, v1);
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}
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/**
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* Returns an immutable map containing the given entries, in order.
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*
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* @throws IllegalArgumentException if duplicate keys or values are added
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*/
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public static <K, V> ImmutableBiMap<K, V> of(K k1, V v1, K k2, V v2) {
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return RegularImmutableBiMap.fromEntries(entryOf(k1, v1), entryOf(k2, v2));
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}
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/**
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* Returns an immutable map containing the given entries, in order.
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*
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* @throws IllegalArgumentException if duplicate keys or values are added
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*/
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public static <K, V> ImmutableBiMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3) {
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return RegularImmutableBiMap.fromEntries(entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3));
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}
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/**
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* Returns an immutable map containing the given entries, in order.
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*
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* @throws IllegalArgumentException if duplicate keys or values are added
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*/
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public static <K, V> ImmutableBiMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
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return RegularImmutableBiMap.fromEntries(
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entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4));
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}
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/**
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* Returns an immutable map containing the given entries, in order.
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*
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* @throws IllegalArgumentException if duplicate keys or values are added
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*/
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public static <K, V> ImmutableBiMap<K, V> of(
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K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
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return RegularImmutableBiMap.fromEntries(
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entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4), entryOf(k5, v5));
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}
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// looking for of() with > 5 entries? Use the builder instead.
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/**
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* Returns a new builder. The generated builder is equivalent to the builder created by the {@link
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* Builder} constructor.
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*/
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public static <K, V> Builder<K, V> builder() {
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return new Builder<>();
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}
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/**
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* Returns a new builder, expecting the specified number of entries to be added.
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*
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* <p>If {@code expectedSize} is exactly the number of entries added to the builder before {@link
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* Builder#build} is called, the builder is likely to perform better than an unsized {@link
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* #builder()} would have.
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*
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* <p>It is not specified if any performance benefits apply if {@code expectedSize} is close to,
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* but not exactly, the number of entries added to the builder.
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*
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* @since 23.1
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*/
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@Beta
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public static <K, V> Builder<K, V> builderWithExpectedSize(int expectedSize) {
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checkNonnegative(expectedSize, "expectedSize");
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return new Builder<>(expectedSize);
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}
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/**
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* A builder for creating immutable bimap instances, especially {@code public static final} bimaps
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* ("constant bimaps"). Example:
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*
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* <pre>{@code
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* static final ImmutableBiMap<String, Integer> WORD_TO_INT =
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* new ImmutableBiMap.Builder<String, Integer>()
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* .put("one", 1)
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* .put("two", 2)
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* .put("three", 3)
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* .build();
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* }</pre>
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*
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* <p>For <i>small</i> immutable bimaps, the {@code ImmutableBiMap.of()} methods are even more
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* convenient.
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*
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* <p>By default, a {@code Builder} will generate bimaps that iterate over entries in the order
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* they were inserted into the builder. For example, in the above example, {@code
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* WORD_TO_INT.entrySet()} is guaranteed to iterate over the entries in the order {@code "one"=1,
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* "two"=2, "three"=3}, and {@code keySet()} and {@code values()} respect the same order. If you
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* want a different order, consider using {@link #orderEntriesByValue(Comparator)}, which changes
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* this builder to sort entries by value.
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*
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* <p>Builder instances can be reused - it is safe to call {@link #build} multiple times to build
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* multiple bimaps in series. Each bimap is a superset of the bimaps created before it.
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*
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* @since 2.0
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*/
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public static final class Builder<K, V> extends ImmutableMap.Builder<K, V> {
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/**
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* Creates a new builder. The returned builder is equivalent to the builder generated by {@link
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* ImmutableBiMap#builder}.
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*/
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public Builder() {}
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Builder(int size) {
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super(size);
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}
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/**
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* Associates {@code key} with {@code value} in the built bimap. Duplicate keys or values are
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* not allowed, and will cause {@link #build} to fail.
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*/
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@Override
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public Builder<K, V> put(K key, V value) {
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super.put(key, value);
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return this;
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}
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/**
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* Adds the given {@code entry} to the bimap. Duplicate keys or values are not allowed, and will
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* cause {@link #build} to fail.
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*
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* @since 19.0
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*/
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@Override
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public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
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super.put(entry);
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return this;
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}
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/**
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* Associates all of the given map's keys and values in the built bimap. Duplicate keys or
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* values are not allowed, and will cause {@link #build} to fail.
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*
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* @throws NullPointerException if any key or value in {@code map} is null
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*/
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@Override
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public Builder<K, V> putAll(Map<? extends K, ? extends V> map) {
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super.putAll(map);
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return this;
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}
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/**
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* Adds all of the given entries to the built bimap. Duplicate keys or values are not allowed,
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* and will cause {@link #build} to fail.
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*
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* @throws NullPointerException if any key, value, or entry is null
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* @since 19.0
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*/
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@Beta
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@Override
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public Builder<K, V> putAll(Iterable<? extends Entry<? extends K, ? extends V>> entries) {
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super.putAll(entries);
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return this;
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}
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/**
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* Configures this {@code Builder} to order entries by value according to the specified
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* comparator.
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*
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* <p>The sort order is stable, that is, if two entries have values that compare as equivalent,
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* the entry that was inserted first will be first in the built map's iteration order.
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*
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* @throws IllegalStateException if this method was already called
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* @since 19.0
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*/
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@Beta
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@Override
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public Builder<K, V> orderEntriesByValue(Comparator<? super V> valueComparator) {
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super.orderEntriesByValue(valueComparator);
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return this;
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}
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@Override
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Builder<K, V> combine(ImmutableMap.Builder<K, V> builder) {
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super.combine(builder);
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return this;
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}
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/**
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* Returns a newly-created immutable bimap. The iteration order of the returned bimap is the
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* order in which entries were inserted into the builder, unless {@link #orderEntriesByValue}
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* was called, in which case entries are sorted by value.
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*
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* @throws IllegalArgumentException if duplicate keys or values were added
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*/
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@Override
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public ImmutableBiMap<K, V> build() {
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switch (size) {
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case 0:
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return of();
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case 1:
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return of(entries[0].getKey(), entries[0].getValue());
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default:
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/*
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* If entries is full, or if hash flooding is detected, then this implementation may end
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* up using the entries array directly and writing over the entry objects with
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* non-terminal entries, but this is safe; if this Builder is used further, it will grow
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* the entries array (so it can't affect the original array), and future build() calls
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* will always copy any entry objects that cannot be safely reused.
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*/
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if (valueComparator != null) {
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if (entriesUsed) {
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entries = Arrays.copyOf(entries, size);
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}
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Arrays.sort(
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entries,
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0,
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size,
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Ordering.from(valueComparator).onResultOf(Maps.<V>valueFunction()));
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}
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entriesUsed = true;
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return RegularImmutableBiMap.fromEntryArray(size, entries);
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}
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}
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@Override
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@VisibleForTesting
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ImmutableBiMap<K, V> buildJdkBacked() {
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checkState(
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valueComparator == null,
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"buildJdkBacked is for tests only, doesn't support orderEntriesByValue");
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switch (size) {
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case 0:
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return of();
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case 1:
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return of(entries[0].getKey(), entries[0].getValue());
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default:
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entriesUsed = true;
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return RegularImmutableBiMap.fromEntryArray(size, entries);
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}
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}
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}
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/**
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* Returns an immutable bimap containing the same entries as {@code map}. If {@code map} somehow
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* contains entries with duplicate keys (for example, if it is a {@code SortedMap} whose
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* comparator is not <i>consistent with equals</i>), the results of this method are undefined.
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*
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* <p>The returned {@code BiMap} iterates over entries in the same order as the {@code entrySet}
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* of the original map.
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*
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* <p>Despite the method name, this method attempts to avoid actually copying the data when it is
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* safe to do so. The exact circumstances under which a copy will or will not be performed are
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* undocumented and subject to change.
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*
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* @throws IllegalArgumentException if two keys have the same value or two values have the same
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* key
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* @throws NullPointerException if any key or value in {@code map} is null
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*/
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public static <K, V> ImmutableBiMap<K, V> copyOf(Map<? extends K, ? extends V> map) {
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if (map instanceof ImmutableBiMap) {
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@SuppressWarnings("unchecked") // safe since map is not writable
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ImmutableBiMap<K, V> bimap = (ImmutableBiMap<K, V>) map;
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// TODO(lowasser): if we need to make a copy of a BiMap because the
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// forward map is a view, don't make a copy of the non-view delegate map
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if (!bimap.isPartialView()) {
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return bimap;
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}
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}
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return copyOf(map.entrySet());
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}
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/**
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* Returns an immutable bimap containing the given entries. The returned bimap iterates over
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* entries in the same order as the original iterable.
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*
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* @throws IllegalArgumentException if two keys have the same value or two values have the same
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* key
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* @throws NullPointerException if any key, value, or entry is null
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* @since 19.0
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*/
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@Beta
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public static <K, V> ImmutableBiMap<K, V> copyOf(
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Iterable<? extends Entry<? extends K, ? extends V>> entries) {
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@SuppressWarnings("unchecked") // we'll only be using getKey and getValue, which are covariant
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Entry<K, V>[] entryArray = (Entry<K, V>[]) Iterables.toArray(entries, EMPTY_ENTRY_ARRAY);
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switch (entryArray.length) {
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case 0:
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return of();
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case 1:
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Entry<K, V> entry = entryArray[0];
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return of(entry.getKey(), entry.getValue());
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default:
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/*
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* The current implementation will end up using entryArray directly, though it will write
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* over the (arbitrary, potentially mutable) Entry objects actually stored in entryArray.
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*/
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return RegularImmutableBiMap.fromEntries(entryArray);
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}
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}
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ImmutableBiMap() {}
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/**
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* {@inheritDoc}
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*
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* <p>The inverse of an {@code ImmutableBiMap} is another {@code ImmutableBiMap}.
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*/
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@Override
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public abstract ImmutableBiMap<V, K> inverse();
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/**
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* Returns an immutable set of the values in this map, in the same order they appear in {@link
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* #entrySet}.
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*/
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@Override
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public ImmutableSet<V> values() {
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return inverse().keySet();
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}
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@Override
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final ImmutableSet<V> createValues() {
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throw new AssertionError("should never be called");
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}
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/**
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* Guaranteed to throw an exception and leave the bimap unmodified.
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*
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* @throws UnsupportedOperationException always
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* @deprecated Unsupported operation.
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*/
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@Deprecated
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@Override
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public V forcePut(K key, V value) {
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throw new UnsupportedOperationException();
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}
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/**
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* Serialized type for all ImmutableBiMap instances. It captures the logical contents and they are
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* reconstructed using public factory methods. This ensures that the implementation types remain
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* as implementation details.
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*
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* <p>Since the bimap is immutable, ImmutableBiMap doesn't require special logic for keeping the
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* bimap and its inverse in sync during serialization, the way AbstractBiMap does.
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*/
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private static class SerializedForm extends ImmutableMap.SerializedForm {
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SerializedForm(ImmutableBiMap<?, ?> bimap) {
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super(bimap);
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}
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@Override
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Object readResolve() {
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||
|
Builder<Object, Object> builder = new Builder<>();
|
||
|
return createMap(builder);
|
||
|
}
|
||
|
|
||
|
private static final long serialVersionUID = 0;
|
||
|
}
|
||
|
|
||
|
@Override
|
||
|
Object writeReplace() {
|
||
|
return new SerializedForm(this);
|
||
|
}
|
||
|
}
|