/*
* 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.GwtCompatible;
import java.util.concurrent.Future;
import javax.annotation.Nullable;
/**
* Transforms a value, possibly asynchronously. For an example usage and more information, see
* {@link Futures#transformAsync(ListenableFuture, AsyncFunction, Executor)}.
*
* @author Chris Povirk
* @since 11.0
*/
@GwtCompatible
public interface AsyncFunction<I, O> {
/**
* Returns an output {@code Future} to use in place of the given {@code input}. The output {@code
* Future} need not be {@linkplain Future#isDone done}, making {@code AsyncFunction} suitable for
* asynchronous derivations.
*
* <p>Throwing an exception from this method is equivalent to returning a failing {@code Future}.
*/
ListenableFuture<O> apply(@Nullable I input) throws Exception;
}