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/*
* Copyright (C) 2007 Google Inc.
*
* 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.base.Nullable;
import java.util.Map;
import java.util.Set;
/**
* 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.
*
* @author Kevin Bourrillion
*/
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.
*/
V put(@Nullable K key, @Nullable 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 which was previously associated with the key, which may
* be {@code null}, or {@code null} if there was no previous entry
*/
V forcePut(@Nullable K key, @Nullable 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.
*/
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.
*/
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();
}