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.internal.observers.BasicQueueDisposable;
  
  import java.util.Objects;
  
  public final class ObservableFromArray<T> extends Observable<T> {
      final T[] array;
      public ObservableFromArray(T[] array) {
          this.array = array;
      }
  
      @Override
      public void subscribeActual(Observer<? super T> observer) {
          FromArrayDisposable<T> d = new FromArrayDisposable<>(observer, array);
  
          observer.onSubscribe(d);
  
          if (d.fusionMode) {
              return;
          }
  
          d.run();
      }
  
      static final class FromArrayDisposable<T> extends BasicQueueDisposable<T> {
  
          final Observer<? super T> downstream;
  
          final T[] array;
  
          int index;
  
          boolean fusionMode;
  
          volatile boolean disposed;
  
          FromArrayDisposable(Observer<? super T> actual, T[] array) {
              this.downstream = actual;
              this.array = array;
          }
  
          @Override
          public int requestFusion(int mode) {
              if ((mode & SYNC) != 0) {
                  fusionMode = true;
                  return SYNC;
              }
              return NONE;
          }
  
          @Nullable
          @Override
          public T poll() {
              int i = index;
              T[] a = array;
              if (i != a.length) {
                  index = i + 1;
                  return Objects.requireNonNull(a[i], "The array element is null");
              }
              return null;
          }
  
          @Override
          public boolean isEmpty() {
              return index == array.length;
          }
  
          @Override
          public void clear() {
              index = array.length;
          }
  
          @Override
          public void dispose() {
              disposed = true;
          }
  
          @Override
          public boolean isDisposed() {
              return disposed;
          }
  
          void run() {
              T[] a = array;
              int n = a.length;
  
              for (int i = 0; i < n && !isDisposed(); i++) {
                  T value = a[i];
                  if (value == null) {
                      downstream.onError(new NullPointerException("The element at index " + i + " is null"));
                      return;
                  }
                  downstream.onNext(value);
              }
              if (!isDisposed()) {
                  downstream.onComplete();
              }
          }
      }
  }
  