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.observable;
  
  import io.reactivex.rxjava3.annotations.Nullable;
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.functions.Consumer;
  import io.reactivex.rxjava3.internal.observers.BasicFuseableObserver;
  
  /**
   * Calls a consumer after pushing the current item to the downstream.
   * <p>History: 2.0.1 - experimental
   * @param <T> the value type
   * @since 2.1
   */
  public final class ObservableDoAfterNext<T> extends AbstractObservableWithUpstream<T, T> {
  
      final Consumer<? super T> onAfterNext;
  
      public ObservableDoAfterNext(ObservableSource<T> source, Consumer<? super T> onAfterNext) {
          super(source);
          this.onAfterNext = onAfterNext;
      }
  
      @Override
      protected void subscribeActual(Observer<? super T> observer) {
          source.subscribe(new DoAfterObserver<>(observer, onAfterNext));
      }
  
      static final class DoAfterObserver<T> extends BasicFuseableObserver<T, T> {
  
          final Consumer<? super T> onAfterNext;
  
          DoAfterObserver(Observer<? super T> actual, Consumer<? super T> onAfterNext) {
              super(actual);
              this.onAfterNext = onAfterNext;
          }
  
          @Override
          public void onNext(T t) {
              downstream.onNext(t);
  
              if (sourceMode == NONE) {
                  try {
                      onAfterNext.accept(t);
                  } catch (Throwable ex) {
                      fail(ex);
                  }
              }
          }
  
          @Override
          public int requestFusion(int mode) {
              return transitiveBoundaryFusion(mode);
          }
  
          @Nullable
          @Override
          public T poll() throws Throwable {
              T v = qd.poll();
              if (v != null) {
                  onAfterNext.accept(v);
              }
              return v;
          }
      }
  }
  