All Downloads are FREE. Search and download functionalities are using the official Maven repository.

com.facebook.presto.jdbc.internal.guava.collect.ForwardingMapEntry Maven / Gradle / Ivy

There is a newer version: 0.289
Show newest version
/*
 * 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.facebook.presto.jdbc.internal.guava.collect;

import com.facebook.presto.jdbc.internal.guava.annotations.Beta;
import com.facebook.presto.jdbc.internal.guava.annotations.GwtCompatible;
import com.facebook.presto.jdbc.internal.guava.base.Objects;
import java.util.Map;
import java.util.Map.Entry;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A map entry which forwards all its method calls to another map entry. Subclasses should override
 * one or more methods to modify the behavior of the backing map entry as desired per the decorator pattern.
 *
 * 

Warning: The methods of {@code ForwardingMapEntry} forward indiscriminately to * the methods of the delegate. For example, overriding {@link #getValue} alone will not * change the behavior of {@link #equals}, which can lead to unexpected behavior. In this case, you * should override {@code equals} as well, either providing your own implementation, or delegating * to the provided {@code standardEquals} method. * *

Each of the {@code standard} methods, where appropriate, use {@link Objects#equal} to test * equality for both keys and values. This may not be the desired behavior for map implementations * that use non-standard notions of key equality, such as the entry of a {@code SortedMap} whose * comparator is not consistent with {@code equals}. * *

The {@code standard} methods are not guaranteed to be thread-safe, even when all of the * methods that they depend on are thread-safe. * * @author Mike Bostock * @author Louis Wasserman * @since 2.0 */ @GwtCompatible public abstract class ForwardingMapEntry extends ForwardingObject implements Map.Entry { // TODO(lowasser): identify places where thread safety is actually lost /** Constructor for use by subclasses. */ protected ForwardingMapEntry() {} @Override protected abstract Entry delegate(); @Override public K getKey() { return delegate().getKey(); } @Override public V getValue() { return delegate().getValue(); } @Override public V setValue(V value) { return delegate().setValue(value); } @Override public boolean equals(@Nullable Object object) { return delegate().equals(object); } @Override public int hashCode() { return delegate().hashCode(); } /** * A sensible definition of {@link #equals(Object)} in terms of {@link #getKey()} and {@link * #getValue()}. If you override either of these methods, you may wish to override {@link * #equals(Object)} to forward to this implementation. * * @since 7.0 */ protected boolean standardEquals(@Nullable Object object) { if (object instanceof Entry) { Entry that = (Entry) object; return Objects.equal(this.getKey(), that.getKey()) && Objects.equal(this.getValue(), that.getValue()); } return false; } /** * A sensible definition of {@link #hashCode()} in terms of {@link #getKey()} and {@link * #getValue()}. If you override either of these methods, you may wish to override {@link * #hashCode()} to forward to this implementation. * * @since 7.0 */ protected int standardHashCode() { K k = getKey(); V v = getValue(); return ((k == null) ? 0 : k.hashCode()) ^ ((v == null) ? 0 : v.hashCode()); } /** * A sensible definition of {@link #toString} in terms of {@link #getKey} and {@link #getValue}. * If you override either of these methods, you may wish to override {@link #equals} to forward to * this implementation. * * @since 7.0 */ @Beta protected String standardToString() { return getKey() + "=" + getValue(); } }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy