package com.google.common.util.concurrent;

import static com.google.common.truth.Truth.assertThat;
import static com.google.common.util.concurrent.Futures.getDone;
import static com.google.common.util.concurrent.Futures.immediateFuture;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
import static com.google.common.util.concurrent.ReflectionFreeAssertThrows.assertThrows;

    // oldFuture completes.
    Runnable listener =
        () -> {
          if (taskFuture.isDone()) {
            // Since the value of oldFuture can only ever be immediateFuture(null) or setFuture of
            // a future that eventually came from immediateFuture(null), this doesn't leak
            // throwables or completion values.
            newFuture.setFuture(oldFuture);

      @ParametricNullness V value) {
    if (value == null) {
      // This cast is safe because null is assignable to V for all V (i.e. it is bivariant)
      @SuppressWarnings("unchecked")
      ListenableFuture<V> typedNull = (ListenableFuture<V>) ImmediateFuture.NULL;
      return typedNull;
    }
    return new ImmediateFuture<>(value);
  }

  /**

      checkNotNull(
          replacement,
          "AsyncFunction.apply returned null instead of a Future. "
              + "Did you mean to return immediateFuture(null)? %s",
          fallback);
      return replacement;
    }

    @Override
    void setResult(ListenableFuture<? extends V> result) {
      setFuture(result);
    }
  }

  /**

import static com.google.common.util.concurrent.Futures.immediateCancelledFuture;
import static com.google.common.util.concurrent.Futures.immediateFailedFuture;
import static com.google.common.util.concurrent.Futures.immediateFuture;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static java.util.concurrent.TimeUnit.NANOSECONDS;

   * // counters.
   * ListenableFuture<Integer> faultTolerantFuture =
   *     fetchCounters().catchingAsync(
   *         FetchException.class, x -> immediateFuture(0), directExecutor());
   * }</pre>
   *
   * <p>The fallback can also choose to propagate the original exception when desired:
   *
   * <pre>{@code

      checkNotNull(
          outputFuture,
          "AsyncFunction.apply returned null instead of a Future. "
              + "Did you mean to return immediateFuture(null)? %s",
          function);
      return outputFuture;
    }

    @Override
    void setResult(ListenableFuture<? extends O> result) {
      setFuture(result);
    }
  }

  /**

import static com.google.common.truth.Truth.assertThat;
import static com.google.common.util.concurrent.Futures.immediateFailedFuture;
import static com.google.common.util.concurrent.Futures.immediateFuture;
import static java.util.Arrays.asList;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static java.util.concurrent.TimeUnit.SECONDS;
import static org.junit.Assert.assertThrows;

        notifyAndClearListeners();
        return;
      }

      /*
       * Almost everything in GWT is an AbstractFuture (which is as good as TrustedFuture under
       * GWT). But ImmediateFuture and UncheckedThrowingFuture aren't, so we still need this case.
       */
      try {
        forceSet(getDone(delegate));
      } catch (ExecutionException exception) {

            return newValue;
          }
          try {
            return getAndRecordStats(key, hash, computingValueReference, immediateFuture(newValue));
          } catch (ExecutionException exception) {
            throw new AssertionError("impossible; Futures.immediateFuture can't throw");
          }
        } else if (createNewEntry || valueReference.isLoading()) {