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 java.util.Collection;
  
  import org.reactivestreams.*;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.Supplier;
  import io.reactivex.rxjava3.internal.subscriptions.*;
  import io.reactivex.rxjava3.internal.util.ExceptionHelper;
  
  public final class FlowableToList<T, U extends Collection<? super T>> extends AbstractFlowableWithUpstream<T, U> {
      final Supplier<U> collectionSupplier;
  
      public FlowableToList(Flowable<T> source, Supplier<U> collectionSupplier) {
          super(source);
          this.collectionSupplier = collectionSupplier;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super U> s) {
          U coll;
          try {
              coll = ExceptionHelper.nullCheck(collectionSupplier.get(), "The collectionSupplier returned a null Collection.");
          } catch (Throwable e) {
              Exceptions.throwIfFatal(e);
              EmptySubscription.error(e, s);
              return;
          }
          source.subscribe(new ToListSubscriber<>(s, coll));
      }
  
      static final class ToListSubscriber<T, U extends Collection<? super T>>
      extends DeferredScalarSubscription<U>
      implements FlowableSubscriber<T> {
  
          private static final long serialVersionUID = -8134157938864266736L;
          Subscription upstream;
  
          ToListSubscriber(Subscriber<? super U> actual, U collection) {
              super(actual);
              this.value = collection;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
                  downstream.onSubscribe(this);
                  s.request(Long.MAX_VALUE);
              }
          }
  
          @Override
          public void onNext(T t) {
              U v = value;
              if (v != null) {
                  v.add(t);
              }
          }
  
          @Override
          public void onError(Throwable t) {
              value = null;
              downstream.onError(t);
          }
  
          @Override
          public void onComplete() {
              complete(value);
          }
  
          @Override
          public void cancel() {
              super.cancel();
              upstream.cancel();
          }
      }
  }
  