/**
 * 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 extends @Nullable Object, O extends @Nullable Object> {
  /**
   * Returns an output {@code Future} to use in place of the given {@code input}. The output {@code

          throw new RejectedExecutionException();
        }
      };

  private static <V> AsyncFunction<V, V> asyncIdentity() {
    return Futures::immediateFuture;
  }

  private static <I, O> AsyncFunction<I, O> tagged(String toString, AsyncFunction<I, O> function) {
    return new AsyncFunction<I, O>() {
      @Override
      public ListenableFuture<O> apply(I input) throws Exception {

          throw new RejectedExecutionException();
        }
      };

  private static <V> AsyncFunction<V, V> asyncIdentity() {
    return Futures::immediateFuture;
  }

  private static <I, O> AsyncFunction<I, O> tagged(String toString, AsyncFunction<I, O> function) {
    return new AsyncFunction<I, O>() {
      @Override
      public ListenableFuture<O> apply(I input) throws Exception {

        AsyncFunction<? super X, ? extends V> fallback) {
      super(input, exceptionType, fallback);
    }

    @Override
    ListenableFuture<? extends V> doFallback(
        AsyncFunction<? super X, ? extends V> fallback, X cause) throws Exception {
      ListenableFuture<? extends V> output = fallback.apply(cause);
      checkNotNull(
          output,

      super(inputFuture, function);
    }

    @Override
    ListenableFuture<? extends O> doTransform(
        AsyncFunction<? super I, ? extends O> function, @ParametricNullness I input)
        throws Exception {
      ListenableFuture<? extends O> output = function.apply(input);
      checkNotNull(
          output,

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import org.jspecify.annotations.NullUnmarked;

/**
 * Unit tests for {@link Futures#transformAsync(ListenableFuture, AsyncFunction, Executor)}.
 *
 * @author Nishant Thakkar
 */
@NullUnmarked
@GwtIncompatible
@J2ktIncompatible
public class FuturesTransformAsyncTest extends AbstractChainedListenableFutureTest<String> {

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import org.jspecify.annotations.NullUnmarked;

/**
 * Unit tests for {@link Futures#transformAsync(ListenableFuture, AsyncFunction, Executor)}.
 *
 * @author Nishant Thakkar
 */
@NullUnmarked
@GwtIncompatible
@J2ktIncompatible
public class FuturesTransformAsyncTest extends AbstractChainedListenableFutureTest<String> {

      Class<X> exceptionType, AsyncClosingFunction<? super X, W> fallback, Executor executor) {
    checkNotNull(fallback);
    AsyncFunction<X, W> asyncFunction =
        new AsyncFunction<X, W>() {
          @Override
          public ListenableFuture<W> apply(X exception) throws Exception {
            return state.closeables.applyAsyncClosingFunction(fallback, exception);

  /**
   * Returns a {@code Future} whose result is taken from this {@code Future} or, if this {@code
   * Future} fails with the given {@code exceptionType}, from the result provided by the {@code
   * fallback}. {@link AsyncFunction#apply} is not invoked until the primary input has failed, so if
   * the primary input succeeds, it is never invoked. If, during the invocation of {@code fallback},

      Executor executor) {
    return (FluentFuture<V>) Futures.catching(this, exceptionType, fallback, executor);
  }

  public final FluentFuture<V> catchingAsync(
      Class<Throwable> exceptionType,
      AsyncFunction<? super Throwable, ? extends V> fallback,
      Executor executor) {
    return (FluentFuture<V>) Futures.catchingAsync(this, exceptionType, fallback, executor);
  }