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.flowable;
  
  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.fuseable.*;
  
  /**
   * Wrap a Completable into a Flowable.
   *
   * @param <T> the value type
   * @since 3.0.0
   */
  public final class FlowableFromCompletable<T> extends Flowable<T> implements HasUpstreamCompletableSource {
  
      final CompletableSource source;
  
      public FlowableFromCompletable(CompletableSource source) {
          this.source = source;
      }
  
      @Override
      public CompletableSource source() {
          return source;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super T> observer) {
          source.subscribe(new FromCompletableObserver<T>(observer));
      }
  
      public static final class FromCompletableObserver<T>
      extends AbstractEmptyQueueFuseable<T>
      implements CompletableObserver {
  
          final Subscriber<? super T> downstream;
  
          Disposable upstream;
  
          public FromCompletableObserver(Subscriber<? super T> downstream) {
              this.downstream = downstream;
          }
  
          @Override
          public void cancel() {
              upstream.dispose();
              upstream = DisposableHelper.DISPOSED;
          }
  
          @Override
          public void onSubscribe(Disposable d) {
              if (DisposableHelper.validate(this.upstream, d)) {
                  this.upstream = d;
  
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public void onComplete() {
              upstream = DisposableHelper.DISPOSED;
              downstream.onComplete();
          }
  
          @Override
          public void onError(Throwable e) {
              upstream = DisposableHelper.DISPOSED;
              downstream.onError(e);
          }
      }
  }
  