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/*
* 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.Beta;
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 javax.annotation.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
* <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
*
* @author Charles Fry
* @since 10.0
*/
@Beta
public abstract class ForwardingCache<K, V> extends ForwardingObject implements Cache<K, V> {
/** Constructor for use by subclasses. */
protected ForwardingCache() {}
@Override
protected abstract Cache<K, V> delegate();
/**
* @since 11.0
*/
@Override
@Nullable
public V getIfPresent(Object key) {
return delegate().getIfPresent(key);
}
/**
* @since 11.0
*/
@Override
public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException {
return delegate().get(key, valueLoader);
}
/**
* @since 11.0
*/
@Override
public ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
return delegate().getAllPresent(keys);
}
/**
* @since 11.0
*/
@Override
public void put(K key, V value) {
delegate().put(key, value);
}
/**
* @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
*/
@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 {@link ForwardingCache} where subclasses can pass in an already
* constructed {@link Cache} as the delegete.
*
* @since 10.0
*/
@Beta
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;
}
}
}
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