1/*
2 * Copyright (C) 2011 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.common.util.concurrent;
18
19import com.google.common.annotations.Beta;
20
21import java.util.concurrent.Future;
22
23/**
24 * Transforms a value, possibly asynchronously. For an example usage and more
25 * information, see {@link Futures#transform(ListenableFuture, AsyncFunction)}.
26 *
27 * @author Chris Povirk
28 * @since 11.0
29 */
30@Beta
31public interface AsyncFunction<I, O> {
32  /**
33   * Returns an output {@code Future} to use in place of the given {@code
34   * input}. The output {@code Future} need not be {@linkplain Future#isDone
35   * done}, making {@code AsyncFunction} suitable for asynchronous derivations.
36   *
37   * <p>Throwing an exception from this method is equivalent to returning a
38   * failing {@code Future}.
39   */
40  ListenableFuture<O> apply(I input) throws Exception;
41}
42