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/*
 * Copyright (C) 2008 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 org.eclipse.papyrus.infra.guava.internal;

import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.util.concurrent.ForwardingListenableFuture;
import com.google.common.util.concurrent.ListenableFuture;

/**
 * A delegating wrapper around a {@link ListenableFuture} that adds support for the {@link
 * #checkedGet()} and {@link #checkedGet(long, TimeUnit)} methods.
 *
 * @author Sven Mawson
 * @since 1.0
 * @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 January 2019.
 */
// TODO(b/72241575): Remove by 2019-01
@Beta
@Deprecated
@GwtIncompatible
public abstract class AbstractCheckedFuture<V, X extends Exception>
		extends ForwardingListenableFuture.SimpleForwardingListenableFuture<V>
		implements CheckedFuture<V, X> {
	/** Constructs an {@code AbstractCheckedFuture} that wraps a delegate. */
	protected AbstractCheckedFuture(ListenableFuture<V> delegate) {
		super(delegate);
	}

	/**
	 * Translates from an {@link InterruptedException}, {@link CancellationException} or {@link
	 * ExecutionException} thrown by {@code get} to an exception of type {@code X} to be thrown by
	 * {@code checkedGet}. Subclasses must implement this method.
	 *
	 * <p>
	 * If {@code e} is an {@code InterruptedException}, the calling {@code checkedGet} method has
	 * already restored the interrupt after catching the exception. If an implementation of {@link
	 * #mapException(Exception)} wishes to swallow the interrupt, it can do so by calling {@link
	 * Thread#interrupted()}.
	 *
	 * <p>
	 * Subclasses may choose to throw, rather than return, a subclass of {@code RuntimeException}
	 * to allow creating a CheckedFuture that throws both checked and unchecked exceptions.
	 */
	// We might like @ForOverride here, but some subclasses invoke this from their get() methods.
	protected abstract X mapException(Exception e);

	/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation calls {@link #get()} and maps that method's standard exceptions to
	 * instances of type {@code X} using {@link #mapException}.
	 *
	 * <p>
	 * In addition, if {@code get} throws an {@link InterruptedException}, this implementation will
	 * set the current thread's interrupt status before calling {@code mapException}.
	 *
	 * @throws X
	 *             if {@link #get()} throws an {@link InterruptedException}, {@link
	 *             CancellationException}, or {@link ExecutionException}
	 */
	@Override
	public V checkedGet() throws X {
		try {
			return get();
		} catch (InterruptedException e) {
			Thread.currentThread().interrupt();
			throw mapException(e);
		} catch (CancellationException | ExecutionException e) {
			throw mapException(e);
		}
	}

	/**
	 * {@inheritDoc}
	 *
	 * <p>
	 * This implementation calls {@link #get(long, TimeUnit)} and maps that method's standard
	 * exceptions (excluding {@link TimeoutException}, which is propagated) to instances of type
	 * {@code X} using {@link #mapException}.
	 *
	 * <p>
	 * In addition, if {@code get} throws an {@link InterruptedException}, this implementation will
	 * set the current thread's interrupt status before calling {@code mapException}.
	 *
	 * @throws X
	 *             if {@link #get()} throws an {@link InterruptedException}, {@link
	 *             CancellationException}, or {@link ExecutionException}
	 */
	@Override
	public V checkedGet(long timeout, TimeUnit unit) throws TimeoutException, X {
		try {
			return get(timeout, unit);
		} catch (InterruptedException e) {
			Thread.currentThread().interrupt();
			throw mapException(e);
		} catch (CancellationException | ExecutionException e) {
			throw mapException(e);
		}
	}
}

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