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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 com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Map;
import java.util.Set;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* A bimap (or "bidirectional map") is a map that preserves the uniqueness of its values as well as
* that of its keys. This constraint enables bimaps to support an "inverse view", which is another
* bimap containing the same entries as this bimap but with reversed keys and values.
*
* See the Guava User Guide article on {@code BiMap}.
*
* @author Kevin Bourrillion
* @since 2.0
*/
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface BiMap extends Map {
// Modification Operations
/**
* {@inheritDoc}
*
* @throws IllegalArgumentException if the given value is already bound to a different key in this
* bimap. The bimap will remain unmodified in this event. To avoid this exception, call {@link
* #forcePut} instead.
*/
@CanIgnoreReturnValue
@Override
@CheckForNull
V put(@ParametricNullness K key, @ParametricNullness V value);
/**
* An alternate form of {@code put} that silently removes any existing entry with the value {@code
* value} before proceeding with the {@link #put} operation. If the bimap previously contained the
* provided key-value mapping, this method has no effect.
*
* Note that a successful call to this method could cause the size of the bimap to increase by
* one, stay the same, or even decrease by one.
*
*
Warning: If an existing entry with this value is removed, the key for that entry is
* discarded and not returned.
*
* @param key the key with which the specified value is to be associated
* @param value the value to be associated with the specified key
* @return the value that was previously associated with the key, or {@code null} if there was no
* previous entry. (If the bimap contains null values, then {@code forcePut}, like {@code
* put}, returns {@code null} both if the key is absent and if it is present with a null
* value.)
*/
@CanIgnoreReturnValue
@CheckForNull
V forcePut(@ParametricNullness K key, @ParametricNullness V value);
// Bulk Operations
/**
* {@inheritDoc}
*
*
Warning: the results of calling this method may vary depending on the iteration order
* of {@code map}.
*
* @throws IllegalArgumentException if an attempt to {@code put} any entry fails. Note that some
* map entries may have been added to the bimap before the exception was thrown.
*/
@Override
void putAll(Map map);
// Views
/**
* {@inheritDoc}
*
*
Because a bimap has unique values, this method returns a {@link Set}, instead of the {@link
* java.util.Collection} specified in the {@link Map} interface.
*/
@Override
Set values();
/**
* Returns the inverse view of this bimap, which maps each of this bimap's values to its
* associated key. The two bimaps are backed by the same data; any changes to one will appear in
* the other.
*
* Note:There is no guaranteed correspondence between the iteration order of a bimap and
* that of its inverse.
*
* @return the inverse view of this bimap
*/
BiMap inverse();
}