/*
 * 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.util.concurrent;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Preconditions;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

A future which forwards all its method calls to another future. Subclasses should override one or
more methods to modify the behavior of the backing future as desired per the decorator pattern.
Most subclasses can simply extend SimpleForwardingCheckedFuture. 
Author:
Anthony Zana
Type parameters:
<V> – The result type returned by this Future's get method
<X> – The type of the Exception thrown by the Future's checkedGet method
Since:
9.0
Deprecated:
CheckedFuture cannot properly support the chained operations that are the primary goal of ListenableFuture. CheckedFuture also encourages users to rethrow exceptions from one thread in another thread, producing misleading stack traces. Additionally, it has a surprising policy about which exceptions to map and which to leave untouched. Guava users who want a CheckedFuture can fork the classes for their own use, possibly specializing them to the particular exception type they use. We recommend that most people use ListenableFuture and perform any exception wrapping themselves. This class is scheduled for removal from Guava in February 2018./**
 * A future which forwards all its method calls to another future. Subclasses should override one or
 * more methods to modify the behavior of the backing future as desired per the <a href=
 * "http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p>Most subclasses can simply extend {@link SimpleForwardingCheckedFuture}.
 *
 * @param <V> The result type returned by this Future's {@code get} method
 * @param <X> The type of the Exception thrown by the Future's {@code checkedGet} method
 * @author Anthony Zana
 * @since 9.0
 * @deprecated {@link CheckedFuture} cannot properly support the chained operations that are the
 *     primary goal of {@link ListenableFuture}. {@code CheckedFuture} also encourages users to
 *     rethrow exceptions from one thread in another thread, producing misleading stack traces.
 *     Additionally, it has a surprising policy about which exceptions to map and which to leave
 *     untouched. Guava users who want a {@code CheckedFuture} can fork the classes for their own
 *     use, possibly specializing them to the particular exception type they use. We recommend that
 *     most people use {@code ListenableFuture} and perform any exception wrapping themselves. This
 *     class is scheduled for removal from Guava in February 2018.
 */
@Beta
@Deprecated
@GwtIncompatible
public abstract class ForwardingCheckedFuture<V, X extends Exception>
    extends ForwardingListenableFuture<V> implements CheckedFuture<V, X> {

  @CanIgnoreReturnValue
  @Override
  public V checkedGet() throws X {
    return delegate().checkedGet();
  }

  @CanIgnoreReturnValue
  @Override
  public V checkedGet(long timeout, TimeUnit unit) throws TimeoutException, X {
    return delegate().checkedGet(timeout, unit);
  }

  @Override
  protected abstract CheckedFuture<V, X> delegate();

  // TODO(cpovirk): Use Standard Javadoc form for SimpleForwarding*
  
A simplified version of ForwardingCheckedFuture where subclasses can pass in an already constructed CheckedFuture as the delegate. 
Since:
9.0
Deprecated:
CheckedFuture cannot properly support the chained operations that are the primary goal of ListenableFuture. CheckedFuture also encourages users to rethrow exceptions from one thread in another thread, producing misleading stack traces. Additionally, it has a surprising policy about which exceptions to map and which to leave untouched. Guava users who want a CheckedFuture can fork the classes for their own use, possibly specializing them to the particular exception type they use. We recommend that most people use ListenableFuture and perform any exception wrapping themselves. This class is scheduled for removal from Guava in February 2018./**
   * A simplified version of {@link ForwardingCheckedFuture} where subclasses can pass in an already
   * constructed {@link CheckedFuture} as the delegate.
   *
   * @since 9.0
   * @deprecated {@link CheckedFuture} cannot properly support the chained operations that are the
   *     primary goal of {@link ListenableFuture}. {@code CheckedFuture} also encourages users to
   *     rethrow exceptions from one thread in another thread, producing misleading stack traces.
   *     Additionally, it has a surprising policy about which exceptions to map and which to leave
   *     untouched. Guava users who want a {@code CheckedFuture} can fork the classes for their own
   *     use, possibly specializing them to the particular exception type they use. We recommend
   *     that most people use {@code ListenableFuture} and perform any exception wrapping
   *     themselves. This class is scheduled for removal from Guava in February 2018.
   */
  @Beta
  @Deprecated
  public abstract static class SimpleForwardingCheckedFuture<V, X extends Exception>
      extends ForwardingCheckedFuture<V, X> {
    private final CheckedFuture<V, X> delegate;

    protected SimpleForwardingCheckedFuture(CheckedFuture<V, X> delegate) {
      this.delegate = Preconditions.checkNotNull(delegate);
    }

    @Override
    protected final CheckedFuture<V, X> delegate() {
      return delegate;
    }
  }
}