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.completable;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.Supplier;
  
  public final class CompletableToSingle<T> extends Single<T> {
      final CompletableSource source;
  
      final Supplier<? extends T> completionValueSupplier;
  
      final T completionValue;
  
      public CompletableToSingle(CompletableSource source,
              Supplier<? extends T> completionValueSupplier, T completionValue) {
          this.source = source;
          this.completionValue = completionValue;
          this.completionValueSupplier = completionValueSupplier;
      }
  
      @Override
      protected void subscribeActual(final SingleObserver<? super T> observer) {
          source.subscribe(new ToSingle(observer));
      }
  
      final class ToSingle implements CompletableObserver {
  
          private final SingleObserver<? super T> observer;
  
          ToSingle(SingleObserver<? super T> observer) {
              this.observer = observer;
          }
  
          @Override
          public void onComplete() {
              T v;
  
              if (completionValueSupplier != null) {
                  try {
                      v = completionValueSupplier.get();
                  } catch (Throwable e) {
                      Exceptions.throwIfFatal(e);
                      observer.onError(e);
                      return;
                  }
              } else {
                  v = completionValue;
              }
  
              if (v == null) {
                  observer.onError(new NullPointerException("The value supplied is null"));
              } else {
                  observer.onSuccess(v);
              }
          }
  
          @Override
          public void onError(Throwable e) {
              observer.onError(e);
          }
  
          @Override
          public void onSubscribe(Disposable d) {
              observer.onSubscribe(d);
          }
  
      }
  }
  