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.jdk8;
  
  import java.util.*;
  
  import org.reactivestreams.*;
  
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.Function;
  import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
  import io.reactivex.rxjava3.operators.ConditionalSubscriber;
  import io.reactivex.rxjava3.parallel.ParallelFlowable;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  
  /**
   * Maps each 'rail' of the source ParallelFlowable with a mapper function.
   *
   * @param <T> the input value type
   * @param <R> the output value type
   * @since 3.0.0
   */
  public final class ParallelMapOptional<T, R> extends ParallelFlowable<R> {
  
      final ParallelFlowable<T> source;
  
      final Function<? super T, Optional<? extends R>> mapper;
  
      public ParallelMapOptional(ParallelFlowable<T> source, Function<? super T, Optional<? extends R>> mapper) {
          this.source = source;
          this.mapper = mapper;
      }
  
      @Override
      public void subscribe(Subscriber<? super R>[] subscribers) {
          if (!validate(subscribers)) {
              return;
          }
  
          int n = subscribers.length;
          @SuppressWarnings("unchecked")
          Subscriber<? super T>[] parents = new Subscriber[n];
  
          for (int i = 0; i < n; i++) {
              Subscriber<? super R> a = subscribers[i];
              if (a instanceof ConditionalSubscriber) {
                  parents[i] = new ParallelMapConditionalSubscriber<>((ConditionalSubscriber<? super R>)a, mapper);
              } else {
                  parents[i] = new ParallelMapSubscriber<>(a, mapper);
              }
          }
  
          source.subscribe(parents);
      }
  
      @Override
      public int parallelism() {
          return source.parallelism();
      }
  
      static final class ParallelMapSubscriber<T, R> implements ConditionalSubscriber<T>, Subscription {
  
          final Subscriber<? super R> downstream;
  
          final Function<? super T, Optional<? extends R>> mapper;
  
          Subscription upstream;
  
          boolean done;
  
          ParallelMapSubscriber(Subscriber<? super R> actual, Function<? super T, Optional<? extends R>> mapper) {
              this.downstream = actual;
              this.mapper = mapper;
          }
  
          @Override
          public void request(long n) {
              upstream.request(n);
          }
  
          @Override
          public void cancel() {
              upstream.cancel();
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
  
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public void onNext(T t) {
              if (!tryOnNext(t)) {
                  upstream.request(1);
              }
          }
  
          @Override
          public boolean tryOnNext(T t) {
              if (done) {
                  return true;
              }
              Optional<? extends R> v;
  
              try {
                  v = Objects.requireNonNull(mapper.apply(t), "The mapper returned a null Optional");
              } catch (Throwable ex) {
                  Exceptions.throwIfFatal(ex);
                  cancel();
                  onError(ex);
                  return true;
              }
  
              if (v.isPresent()) {
                  downstream.onNext(v.get());
                  return true;
              }
              return false;
          }
  
          @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();
          }
  
      }
      static final class ParallelMapConditionalSubscriber<T, R> implements ConditionalSubscriber<T>, Subscription {
  
          final ConditionalSubscriber<? super R> downstream;
  
          final Function<? super T, Optional<? extends R>> mapper;
  
          Subscription upstream;
  
          boolean done;
  
          ParallelMapConditionalSubscriber(ConditionalSubscriber<? super R> actual, Function<? super T, Optional<? extends R>> mapper) {
              this.downstream = actual;
              this.mapper = mapper;
          }
  
          @Override
          public void request(long n) {
              upstream.request(n);
          }
  
          @Override
          public void cancel() {
              upstream.cancel();
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
  
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public void onNext(T t) {
              if (!tryOnNext(t)) {
                  upstream.request(1);
              }
          }
  
          @Override
          public boolean tryOnNext(T t) {
              if (done) {
                  return false;
              }
              Optional<? extends R> v;
  
              try {
                  v = Objects.requireNonNull(mapper.apply(t), "The mapper returned a null value");
              } catch (Throwable ex) {
                  Exceptions.throwIfFatal(ex);
                  cancel();
                  onError(ex);
                  return false;
              }
  
              return v.isPresent() && downstream.tryOnNext(v.get());
          }
  
          @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();
          }
  
      }
  }
  