AsyncFunction.java
/*
* Copyright 2022 The Android Open Source Project
*
* 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 androidx.camera.viewfinder.internal.utils.futures;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import com.google.common.util.concurrent.ListenableFuture;
import java.util.concurrent.Executor;
import java.util.concurrent.Future;
/**
* Cloned from concurrent-futures package in Guava to AndroidX namespace since we would need
* ListenableFuture related implementation but not want to include whole Guava library.
*
* 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
* @param <I>
* @param <O>
*
*/
@FunctionalInterface
@RequiresApi(21) // TODO(b/200306659): Remove and replace with annotation on package-info.java
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}.
*/
@NonNull
ListenableFuture<O> apply(@Nullable I input) throws Exception;
}