code: /*
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * 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 io.reactivex.rxjava3.internal.operators.single;
  
  import org.reactivestreams.Subscriber;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
  import io.reactivex.rxjava3.internal.subscriptions.DeferredScalarSubscription;
  
  /**
   * Wraps a Single and exposes it as a Flowable.
   *
   * @param <T> the value type
   */
  public final class SingleToFlowable<T> extends Flowable<T> {
  
      final SingleSource<? extends T> source;
  
      public SingleToFlowable(SingleSource<? extends T> source) {
          this.source = source;
      }
  
      @Override
      public void subscribeActual(final Subscriber<? super T> s) {
          source.subscribe(new SingleToFlowableObserver<T>(s));
      }
  
      static final class SingleToFlowableObserver<T> extends DeferredScalarSubscription<T>
      implements SingleObserver<T> {
  
          private static final long serialVersionUID = 187782011903685568L;
  
          Disposable upstream;
  
          SingleToFlowableObserver(Subscriber<? super T> downstream) {
              super(downstream);
          }
  
          @Override
          public void onSubscribe(Disposable d) {
              if (DisposableHelper.validate(this.upstream, d)) {
                  this.upstream = d;
  
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public void onSuccess(T value) {
              complete(value);
          }
  
          @Override
          public void onError(Throwable e) {
              downstream.onError(e);
          }
  
          @Override
          public void cancel() {
              super.cancel();
              upstream.dispose();
          }
      }
  }
  