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.Predicate;
  import io.reactivex.rxjava3.internal.subscribers.*;
  import io.reactivex.rxjava3.operators.ConditionalSubscriber;
  import io.reactivex.rxjava3.operators.QueueSubscription;
  
  public final class FlowableFilter<T> extends AbstractFlowableWithUpstream<T, T> {
      final Predicate<? super T> predicate;
      public FlowableFilter(Flowable<T> source, Predicate<? super T> predicate) {
          super(source);
          this.predicate = predicate;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super T> s) {
          if (s instanceof ConditionalSubscriber) {
              source.subscribe(new FilterConditionalSubscriber<>(
                      (ConditionalSubscriber<? super T>) s, predicate));
          } else {
              source.subscribe(new FilterSubscriber<>(s, predicate));
          }
      }
  
      static final class FilterSubscriber<T> extends BasicFuseableSubscriber<T, T>
      implements ConditionalSubscriber<T> {
          final Predicate<? super T> filter;
  
          FilterSubscriber(Subscriber<? super T> actual, Predicate<? super T> filter) {
              super(actual);
              this.filter = filter;
          }
  
          @Override
          public void onNext(T t) {
              if (!tryOnNext(t)) {
                  upstream.request(1);
              }
          }
  
          @Override
          public boolean tryOnNext(T t) {
              if (done) {
                  return false;
              }
              if (sourceMode != NONE) {
                  downstream.onNext(null);
                  return true;
              }
              boolean b;
              try {
                  b = filter.test(t);
              } catch (Throwable e) {
                  fail(e);
                  return true;
              }
              if (b) {
                  downstream.onNext(t);
              }
              return b;
          }
  
          @Override
          public int requestFusion(int mode) {
              return transitiveBoundaryFusion(mode);
          }
  
          @Nullable
          @Override
          public T poll() throws Throwable {
              QueueSubscription<T> qs = this.qs;
              Predicate<? super T> f = filter;
  
              for (;;) {
                  T t = qs.poll();
                  if (t == null) {
                      return null;
                  }
  
                  if (f.test(t)) {
                      return t;
                  }
  
                  if (sourceMode == ASYNC) {
                      qs.request(1);
                  }
              }
          }
      }
  
      static final class FilterConditionalSubscriber<T> extends BasicFuseableConditionalSubscriber<T, T> {
          final Predicate<? super T> filter;
  
          FilterConditionalSubscriber(ConditionalSubscriber<? super T> actual, Predicate<? super T> filter) {
              super(actual);
              this.filter = filter;
          }
  
          @Override
          public void onNext(T t) {
              if (!tryOnNext(t)) {
                  upstream.request(1);
              }
          }
  
          @Override
          public boolean tryOnNext(T t) {
              if (done) {
                  return false;
              }
  
              if (sourceMode != NONE) {
                  return downstream.tryOnNext(null);
              }
  
              boolean b;
              try {
                  b = filter.test(t);
              } catch (Throwable e) {
                  fail(e);
                  return true;
              }
              return b && downstream.tryOnNext(t);
          }
  
          @Override
          public int requestFusion(int mode) {
              return transitiveBoundaryFusion(mode);
          }
  
          @Nullable
          @Override
          public T poll() throws Throwable {
              QueueSubscription<T> qs = this.qs;
              Predicate<? super T> f = filter;
  
              for (;;) {
                  T t = qs.poll();
                  if (t == null) {
                      return null;
                  }
  
                  if (f.test(t)) {
                      return t;
                  }
  
                  if (sourceMode == ASYNC) {
                      qs.request(1);
                  }
              }
          }
      }
  }
  