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.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.Predicate;
  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;
  
  /**
   * Filters each 'rail' of the source ParallelFlowable with a predicate function.
   *
   * @param <T> the input value type
   */
  public final class ParallelFilter<T> extends ParallelFlowable<T> {
  
      final ParallelFlowable<T> source;
  
      final Predicate<? super T> predicate;
  
      public ParallelFilter(ParallelFlowable<T> source, Predicate<? super T> predicate) {
          this.source = source;
          this.predicate = predicate;
      }
  
      @Override
      public void subscribe(Subscriber<? super T>[] subscribers) {
          subscribers = RxJavaPlugins.onSubscribe(this, 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 T> a = subscribers[i];
              if (a instanceof ConditionalSubscriber) {
                  parents[i] = new ParallelFilterConditionalSubscriber<>((ConditionalSubscriber<? super T>)a, predicate);
              } else {
                  parents[i] = new ParallelFilterSubscriber<>(a, predicate);
              }
          }
  
          source.subscribe(parents);
      }
  
      @Override
      public int parallelism() {
          return source.parallelism();
      }
  
      abstract static class BaseFilterSubscriber<T> implements ConditionalSubscriber<T>, Subscription {
          final Predicate<? super T> predicate;
  
          Subscription upstream;
  
          boolean done;
  
          BaseFilterSubscriber(Predicate<? super T> predicate) {
              this.predicate = predicate;
          }
  
          @Override
          public final void request(long n) {
              upstream.request(n);
          }
  
          @Override
          public final void cancel() {
              upstream.cancel();
          }
  
          @Override
          public final void onNext(T t) {
              if (!tryOnNext(t) && !done) {
                  upstream.request(1);
              }
          }
      }
  
      static final class ParallelFilterSubscriber<T> extends BaseFilterSubscriber<T> {
  
          final Subscriber<? super T> downstream;
  
          ParallelFilterSubscriber(Subscriber<? super T> actual, Predicate<? super T> predicate) {
              super(predicate);
              this.downstream = actual;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
  
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public boolean tryOnNext(T t) {
              if (!done) {
                  boolean b;
  
                  try {
                      b = predicate.test(t);
                  } catch (Throwable ex) {
                      Exceptions.throwIfFatal(ex);
                      cancel();
                      onError(ex);
                      return false;
                  }
  
                  if (b) {
                      downstream.onNext(t);
                      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) {
                  done = true;
                  downstream.onComplete();
              }
          }
      }
  
      static final class ParallelFilterConditionalSubscriber<T> extends BaseFilterSubscriber<T> {
  
          final ConditionalSubscriber<? super T> downstream;
  
          ParallelFilterConditionalSubscriber(ConditionalSubscriber<? super T> actual, Predicate<? super T> predicate) {
              super(predicate);
              this.downstream = actual;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.upstream, s)) {
                  this.upstream = s;
  
                  downstream.onSubscribe(this);
              }
          }
  
          @Override
          public boolean tryOnNext(T t) {
              if (!done) {
                  boolean b;
  
                  try {
                      b = predicate.test(t);
                  } catch (Throwable ex) {
                      Exceptions.throwIfFatal(ex);
                      cancel();
                      onError(ex);
                      return false;
                  }
  
                  if (b) {
                      return downstream.tryOnNext(t);
                  }
              }
              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) {
                  done = true;
                  downstream.onComplete();
              }
          }
      }}
  