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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.annotations.GwtCompatible;
import java.util.Map;
import javax.annotation.Nullable;
/**
* An object representing the differences between two maps.
*
* @author Kevin Bourrillion
* @since 2010.01.04 <b>stable</b> (imported from Google Collections Library)
*/
@GwtCompatible
public interface MapDifference<K, V> {
/**
* Returns {@code true} if there are no differences between the two maps;
* that is, if the maps are equal.
*/
boolean areEqual();
/**
* Returns an unmodifiable map containing the entries from the left map whose
* keys are not present in the right map.
*/
Map<K, V> entriesOnlyOnLeft();
/**
* Returns an unmodifiable map containing the entries from the right map whose
* keys are not present in the left map.
*/
Map<K, V> entriesOnlyOnRight();
/**
* Returns an unmodifiable map containing the entries that appear in both
* maps; that is, the intersection of the two maps.
*/
Map<K, V> entriesInCommon();
/**
* Returns an unmodifiable map describing keys that appear in both maps, but
* with different values.
*/
Map<K, ValueDifference<V>> entriesDiffering();
/**
* Compares the specified object with this instance for equality. Returns
* {@code true} if the given object is also a {@code MapDifference} and the
* values returned by the {@link #entriesOnlyOnLeft()}, {@link
* #entriesOnlyOnRight()}, {@link #entriesInCommon()} and {@link
* #entriesDiffering()} of the two instances are equal.
*/
boolean equals(@Nullable Object object);
/**
* Returns the hash code for this instance. This is defined as the hash code
* of <pre> {@code
*
* Arrays.asList(entriesOnlyOnLeft(), entriesOnlyOnRight(),
* entriesInCommon(), entriesDiffering())}</pre>
*/
int hashCode();
/**
* A difference between the mappings from two maps with the same key. The
* {@code leftValue()} and {@code rightValue} are not equal, and one but not
* both of them may be null.
*/
interface ValueDifference<V> {
/**
* Returns the value from the left map (possibly null).
*/
V leftValue();
/**
* Returns the value from the right map (possibly null).
*/
V rightValue();
/**
* Two instances are considered equal if their {@link #leftValue()}
* values are equal and their {@link #rightValue()} values are also equal.
*/
@Override boolean equals(@Nullable Object other);
/**
* The hash code equals the value
* {@code Arrays.asList(leftValue(), rightValue()).hashCode()}.
*/
@Override int hashCode();
}
}