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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.concurrent.ConcurrentMap;
import javax.annotation.CheckForNull;

/**
 * A concurrent map which forwards all its method calls to another concurrent map. Subclasses should
 * override one or more methods to modify the behavior of the backing map as desired per the decorator pattern.
 *
 * {@code default} method warning: This class forwards calls to only some {@code
 * default} methods. Specifically, it forwards calls only for methods that existed before
 * {@code default} methods were introduced. For newer methods, like {@code forEach}, it inherits
 * their default implementations. When those implementations invoke methods, they invoke methods on
 * the {@code ForwardingConcurrentMap}.
 *
 * @author Charles Fry
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class ForwardingConcurrentMap extends ForwardingMap
    implements ConcurrentMap {

  /** Constructor for use by subclasses. */
  protected ForwardingConcurrentMap() {}

  @Override
  protected abstract ConcurrentMap delegate();

  @CanIgnoreReturnValue
  @Override
  @CheckForNull
  public V putIfAbsent(K key, V value) {
    return delegate().putIfAbsent(key, value);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
    return delegate().remove(key, value);
  }

  @CanIgnoreReturnValue
  @Override
  @CheckForNull
  public V replace(K key, V value) {
    return delegate().replace(key, value);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean replace(K key, V oldValue, V newValue) {
    return delegate().replace(key, oldValue, newValue);
  }
}