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.parallel;
  
  import org.reactivestreams.*;
  
  import io.reactivex.rxjava3.functions.Function;
  import io.reactivex.rxjava3.internal.operators.flowable.FlowableFlatMap;
  import io.reactivex.rxjava3.parallel.ParallelFlowable;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  
  /**
   * Flattens the generated Publishers on each rail.
   *
   * @param <T> the input value type
   * @param <R> the output value type
   */
  public final class ParallelFlatMap<T, R> extends ParallelFlowable<R> {
  
      final ParallelFlowable<T> source;
  
      final Function<? super T, ? extends Publisher<? extends R>> mapper;
  
      final boolean delayError;
  
      final int maxConcurrency;
  
      final int prefetch;
  
      public ParallelFlatMap(
              ParallelFlowable<T> source,
              Function<? super T, ? extends Publisher<? extends R>> mapper,
              boolean delayError,
              int maxConcurrency,
              int prefetch) {
          this.source = source;
          this.mapper = mapper;
          this.delayError = delayError;
          this.maxConcurrency = maxConcurrency;
          this.prefetch = prefetch;
      }
  
      @Override
      public int parallelism() {
          return source.parallelism();
      }
  
      @Override
      public void subscribe(Subscriber<? super R>[] subscribers) {
          subscribers = RxJavaPlugins.onSubscribe(this, subscribers);
  
          if (!validate(subscribers)) {
              return;
          }
  
          int n = subscribers.length;
  
          @SuppressWarnings("unchecked")
          final Subscriber<T>[] parents = new Subscriber[n];
  
          for (int i = 0; i < n; i++) {
              parents[i] = FlowableFlatMap.subscribe(subscribers[i], mapper, delayError, maxConcurrency, prefetch);
          }
  
          source.subscribe(parents);
      }
  }
  