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.Subscriber;
  
  import io.reactivex.rxjava3.annotations.Nullable;
  import io.reactivex.rxjava3.core.Flowable;
  import io.reactivex.rxjava3.functions.Function;
  import io.reactivex.rxjava3.internal.subscribers.*;
  import io.reactivex.rxjava3.operators.ConditionalSubscriber;
  
  import java.util.Objects;
  
  public final class FlowableMap<T, U> extends AbstractFlowableWithUpstream<T, U> {
      final Function<? super T, ? extends U> mapper;
      public FlowableMap(Flowable<T> source, Function<? super T, ? extends U> mapper) {
          super(source);
          this.mapper = mapper;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super U> s) {
          if (s instanceof ConditionalSubscriber) {
              source.subscribe(new MapConditionalSubscriber<T, U>((ConditionalSubscriber<? super U>)s, mapper));
          } else {
              source.subscribe(new MapSubscriber<T, U>(s, mapper));
          }
      }
  
      static final class MapSubscriber<T, U> extends BasicFuseableSubscriber<T, U> {
          final Function<? super T, ? extends U> mapper;
  
          MapSubscriber(Subscriber<? super U> actual, Function<? super T, ? extends U> mapper) {
              super(actual);
              this.mapper = mapper;
          }
  
          @Override
          public void onNext(T t) {
              if (done) {
                  return;
              }
  
              if (sourceMode != NONE) {
                  downstream.onNext(null);
                  return;
              }
  
              U v;
  
              try {
                  v = Objects.requireNonNull(mapper.apply(t), "The mapper function returned a null value.");
              } catch (Throwable ex) {
                  fail(ex);
                  return;
              }
              downstream.onNext(v);
          }
  
          @Override
          public int requestFusion(int mode) {
              return transitiveBoundaryFusion(mode);
          }
  
          @Nullable
          @Override
          public U poll() throws Throwable {
              T t = qs.poll();
              return t != null ? Objects.requireNonNull(mapper.apply(t), "The mapper function returned a null value.") : null;
          }
      }
  
      static final class MapConditionalSubscriber<T, U> extends BasicFuseableConditionalSubscriber<T, U> {
          final Function<? super T, ? extends U> mapper;
  
          MapConditionalSubscriber(ConditionalSubscriber<? super U> actual, Function<? super T, ? extends U> function) {
              super(actual);
              this.mapper = function;
          }
  
          @Override
          public void onNext(T t) {
              if (done) {
                  return;
              }
  
              if (sourceMode != NONE) {
                  downstream.onNext(null);
                  return;
              }
  
              U v;
  
              try {
                  v = Objects.requireNonNull(mapper.apply(t), "The mapper function returned a null value.");
              } catch (Throwable ex) {
                  fail(ex);
                  return;
              }
              downstream.onNext(v);
          }
  
          @Override
          public boolean tryOnNext(T t) {
              if (done) {
                  return true;
              }
  
              if (sourceMode != NONE) {
                  downstream.tryOnNext(null);
                  return true;
              }
  
              U v;
  
              try {
                  v = Objects.requireNonNull(mapper.apply(t), "The mapper function returned a null value.");
              } catch (Throwable ex) {
                  fail(ex);
                  return true;
              }
              return downstream.tryOnNext(v);
          }
  
          @Override
          public int requestFusion(int mode) {
              return transitiveBoundaryFusion(mode);
          }
  
          @Nullable
          @Override
          public U poll() throws Throwable {
              T t = qs.poll();
              return t != null ? Objects.requireNonNull(mapper.apply(t), "The mapper function returned a null value.") : null;
          }
      }
  
  }
  