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.*;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.Function;
  import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  
  import java.util.Objects;
  
  public final class FlowableDematerialize<T, R> extends AbstractFlowableWithUpstream<T, R> {
  
      final Function<? super T, ? extends Notification<R>> selector;
  
      public FlowableDematerialize(Flowable<T> source, Function<? super T, ? extends Notification<R>> selector) {
          super(source);
          this.selector = selector;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super R> subscriber) {
          source.subscribe(new DematerializeSubscriber<>(subscriber, selector));
      }
  
      static final class DematerializeSubscriber<T, R> implements FlowableSubscriber<T>, Subscription {
  
          final Subscriber<? super R> downstream;
  
          final Function<? super T, ? extends Notification<R>> selector;
  
          boolean done;
  
          Subscription upstream;
  
          DematerializeSubscriber(Subscriber<? super R> downstream, Function<? super T, ? extends Notification<R>> selector) {
              this.downstream = downstream;
              this.selector = selector;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public void onNext(T item) {
              if (done) {
                  if (item instanceof Notification) {
                      Notification<?> notification = (Notification<?>)item;
                      if (notification.isOnError()) {
                          RxJavaPlugins.onError(notification.getError());
                      }
                  }
                  return;
              }
  
              Notification<R> notification;
  
              try {
                  notification = Objects.requireNonNull(selector.apply(item), "The selector returned a null Notification");
              } catch (Throwable ex) {
                  Exceptions.throwIfFatal(ex);
                  upstream.cancel();
                  onError(ex);
                  return;
              }
              if (notification.isOnError()) {
                  upstream.cancel();
                  onError(notification.getError());
              } else if (notification.isOnComplete()) {
                  upstream.cancel();
                  onComplete();
              } else {
                  downstream.onNext(notification.getValue());
              }
          }
  
          @Override
          public void onError(Throwable t) {
              if (done) {
                  RxJavaPlugins.onError(t);
                  return;
              }
              done = true;
  
              downstream.onError(t);
          }
  
          @Override
          public void onComplete() {
              if (done) {
                  return;
              }
              done = true;
  
              downstream.onComplete();
          }
  
          @Override
          public void request(long n) {
              upstream.request(n);
          }
  
          @Override
          public void cancel() {
              upstream.cancel();
          }
      }
  }
  