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.functions.Function;
  import io.reactivex.rxjava3.internal.operators.flowable.FlowableFlatMapSingle.FlatMapSingleSubscriber;
  
  /**
   * Maps upstream values into SingleSources and merges their signals into one sequence.
   * @param <T> the source value type
   * @param <R> the result value type
   */
  public final class FlowableFlatMapSinglePublisher<T, R> extends Flowable<R> {
  
      final Publisher<T> source;
  
      final Function<? super T, ? extends SingleSource<? extends R>> mapper;
  
      final boolean delayErrors;
  
      final int maxConcurrency;
  
      public FlowableFlatMapSinglePublisher(Publisher<T> source, Function<? super T, ? extends SingleSource<? extends R>> mapper,
              boolean delayError, int maxConcurrency) {
          this.source = source;
          this.mapper = mapper;
          this.delayErrors = delayError;
          this.maxConcurrency = maxConcurrency;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super R> s) {
          source.subscribe(new FlatMapSingleSubscriber<>(s, mapper, delayErrors, maxConcurrency));
      }
  }
  