/*
 * Copyright (C) 2011 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.cache;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Preconditions;
import com.google.common.collect.ForwardingObject;
import com.google.common.collect.ImmutableMap;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutionException;
import org.checkerframework.checker.nullness.qual.Nullable;

A cache which forwards all its method calls to another cache. Subclasses should override one or
more methods to modify the behavior of the backing cache as desired per the decorator pattern.
Author:
Charles Fry
Since:
10.0/**
 * A cache which forwards all its method calls to another cache. Subclasses should override one or
 * more methods to modify the behavior of the backing cache as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * @author Charles Fry
 * @since 10.0
 */
@GwtIncompatible
public abstract class ForwardingCache<K, V> extends ForwardingObject implements Cache<K, V> {

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

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

  
Since:
11.0/** @since 11.0 */
  @Override
  public @Nullable V getIfPresent(Object key) {
    return delegate().getIfPresent(key);
  }

  
Since:
11.0/** @since 11.0 */
  @Override
  public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException {
    return delegate().get(key, valueLoader);
  }

  
Since:
11.0/** @since 11.0 */
  @Override
  public ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
    return delegate().getAllPresent(keys);
  }

  
Since:
11.0/** @since 11.0 */
  @Override
  public void put(K key, V value) {
    delegate().put(key, value);
  }

  
Since:
12.0/** @since 12.0 */
  @Override
  public void putAll(Map<? extends K, ? extends V> m) {
    delegate().putAll(m);
  }

  @Override
  public void invalidate(Object key) {
    delegate().invalidate(key);
  }

  
Since:
11.0/** @since 11.0 */
  @Override
  public void invalidateAll(Iterable<?> keys) {
    delegate().invalidateAll(keys);
  }

  @Override
  public void invalidateAll() {
    delegate().invalidateAll();
  }

  @Override
  public long size() {
    return delegate().size();
  }

  @Override
  public CacheStats stats() {
    return delegate().stats();
  }

  @Override
  public ConcurrentMap<K, V> asMap() {
    return delegate().asMap();
  }

  @Override
  public void cleanUp() {
    delegate().cleanUp();
  }

  
A simplified version of ForwardingCache where subclasses can pass in an already constructed Cache as the delegate. 
Since:
10.0/**
   * A simplified version of {@link ForwardingCache} where subclasses can pass in an already
   * constructed {@link Cache} as the delegate.
   *
   * @since 10.0
   */
  public abstract static class SimpleForwardingCache<K, V> extends ForwardingCache<K, V> {
    private final Cache<K, V> delegate;

    protected SimpleForwardingCache(Cache<K, V> delegate) {
      this.delegate = Preconditions.checkNotNull(delegate);
    }

    @Override
    protected final Cache<K, V> delegate() {
      return delegate;
    }
  }
}