001/*
002 * Copyright (C) 2011 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
005 * in compliance with the License. You may obtain a copy of the License at
006 *
007 * http://www.apache.org/licenses/LICENSE-2.0
008 *
009 * Unless required by applicable law or agreed to in writing, software distributed under the License
010 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
011 * or implied. See the License for the specific language governing permissions and limitations under
012 * the License.
013 */
014
015package com.google.common.cache;
016
017import com.google.common.annotations.GwtIncompatible;
018import com.google.common.base.Preconditions;
019import com.google.common.collect.ForwardingObject;
020import com.google.common.collect.ImmutableMap;
021import java.util.Map;
022import java.util.concurrent.Callable;
023import java.util.concurrent.ConcurrentMap;
024import java.util.concurrent.ExecutionException;
025import org.checkerframework.checker.nullness.qual.Nullable;
026
027/**
028 * A cache which forwards all its method calls to another cache. Subclasses should override one or
029 * more methods to modify the behavior of the backing cache as desired per the <a
030 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
031 *
032 * @author Charles Fry
033 * @since 10.0
034 */
035@GwtIncompatible
036public abstract class ForwardingCache<K, V> extends ForwardingObject implements Cache<K, V> {
037
038  /** Constructor for use by subclasses. */
039  protected ForwardingCache() {}
040
041  @Override
042  protected abstract Cache<K, V> delegate();
043
044  /** @since 11.0 */
045  @Override
046  public @Nullable V getIfPresent(Object key) {
047    return delegate().getIfPresent(key);
048  }
049
050  /** @since 11.0 */
051  @Override
052  public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException {
053    return delegate().get(key, valueLoader);
054  }
055
056  /** @since 11.0 */
057  @Override
058  public ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
059    return delegate().getAllPresent(keys);
060  }
061
062  /** @since 11.0 */
063  @Override
064  public void put(K key, V value) {
065    delegate().put(key, value);
066  }
067
068  /** @since 12.0 */
069  @Override
070  public void putAll(Map<? extends K, ? extends V> m) {
071    delegate().putAll(m);
072  }
073
074  @Override
075  public void invalidate(Object key) {
076    delegate().invalidate(key);
077  }
078
079  /** @since 11.0 */
080  @Override
081  public void invalidateAll(Iterable<?> keys) {
082    delegate().invalidateAll(keys);
083  }
084
085  @Override
086  public void invalidateAll() {
087    delegate().invalidateAll();
088  }
089
090  @Override
091  public long size() {
092    return delegate().size();
093  }
094
095  @Override
096  public CacheStats stats() {
097    return delegate().stats();
098  }
099
100  @Override
101  public ConcurrentMap<K, V> asMap() {
102    return delegate().asMap();
103  }
104
105  @Override
106  public void cleanUp() {
107    delegate().cleanUp();
108  }
109
110  /**
111   * A simplified version of {@link ForwardingCache} where subclasses can pass in an already
112   * constructed {@link Cache} as the delegate.
113   *
114   * @since 10.0
115   */
116  public abstract static class SimpleForwardingCache<K, V> extends ForwardingCache<K, V> {
117    private final Cache<K, V> delegate;
118
119    protected SimpleForwardingCache(Cache<K, V> delegate) {
120      this.delegate = Preconditions.checkNotNull(delegate);
121    }
122
123    @Override
124    protected final Cache<K, V> delegate() {
125      return delegate;
126    }
127  }
128}