/*
 * 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;

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.
default method warning: This class forwards calls to only some 
default methods. Specifically, it forwards calls only for methods that existed before default methods were introduced. For newer methods, like forEach, it inherits their default implementations. When those implementations invoke methods, they invoke methods on the ForwardingConcurrentMap. 
Author:
Charles Fry
Since:
2.0/**
 * 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 <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>{@code default} method warning:</b> This class forwards calls to <i>only some</i> {@code
 * default} methods. Specifically, it forwards calls only for methods that existed <a
 * href="https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ConcurrentMap.html">before
 * {@code default} methods were introduced</a>. 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
public abstract class ForwardingConcurrentMap<K, V> extends ForwardingMap<K, V>
    implements ConcurrentMap<K, V> {

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

  @Override
  protected abstract ConcurrentMap<K, V> delegate();

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

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

  @CanIgnoreReturnValue
  @Override
  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);
  }
}