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.mixed;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
  
  /**
   * A consumer that implements the consumer types of Maybe, Single and Completable
   * and turns their signals into Notifications for a SingleObserver.
   * <p>History: 2.2.4 - experimental
   * @param <T> the element type of the source
   * @since 3.0.0
   */
  public final class MaterializeSingleObserver<T>
  implements SingleObserver<T>, MaybeObserver<T>, CompletableObserver, Disposable {
  
      final SingleObserver<? super Notification<T>> downstream;
  
      Disposable upstream;
  
      public MaterializeSingleObserver(SingleObserver<? super Notification<T>> downstream) {
          this.downstream = downstream;
      }
  
      @Override
      public void onSubscribe(Disposable d) {
          if (DisposableHelper.validate(upstream, d)) {
              this.upstream = d;
              downstream.onSubscribe(this);
          }
      }
  
      @Override
      public void onComplete() {
          downstream.onSuccess(Notification.createOnComplete());
      }
  
      @Override
      public void onSuccess(T t) {
          downstream.onSuccess(Notification.createOnNext(t));
      }
  
      @Override
      public void onError(Throwable e) {
          downstream.onSuccess(Notification.createOnError(e));
      }
  
      @Override
      public boolean isDisposed() {
          return upstream.isDisposed();
      }
  
      @Override
      public void dispose() {
          upstream.dispose();
      }
  }
  