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.maybe;
  
  import java.util.Objects;
  import java.util.concurrent.atomic.*;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.Function;
  import io.reactivex.rxjava3.internal.disposables.DisposableHelper;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  
  public final class MaybeZipArray<T, R> extends Maybe<R> {
  
      final MaybeSource<? extends T>[] sources;
  
      final Function<? super Object[], ? extends R> zipper;
  
      public MaybeZipArray(MaybeSource<? extends T>[] sources, Function<? super Object[], ? extends R> zipper) {
          this.sources = sources;
          this.zipper = zipper;
      }
  
      @Override
      protected void subscribeActual(MaybeObserver<? super R> observer) {
          MaybeSource<? extends T>[] sources = this.sources;
          int n = sources.length;
  
          if (n == 1) {
              sources[0].subscribe(new MaybeMap.MapMaybeObserver<>(observer, new SingletonArrayFunc()));
              return;
          }
  
          ZipCoordinator<T, R> parent = new ZipCoordinator<>(observer, n, zipper);
  
          observer.onSubscribe(parent);
  
          for (int i = 0; i < n; i++) {
              if (parent.isDisposed()) {
                  return;
              }
  
              MaybeSource<? extends T> source = sources[i];
  
              if (source == null) {
                  parent.innerError(new NullPointerException("One of the sources is null"), i);
                  return;
              }
              source.subscribe(parent.observers[i]);
          }
      }
  
      static final class ZipCoordinator<T, R> extends AtomicInteger implements Disposable {
  
          private static final long serialVersionUID = -5556924161382950569L;
  
          final MaybeObserver<? super R> downstream;
  
          final Function<? super Object[], ? extends R> zipper;
  
          final ZipMaybeObserver<T>[] observers;
  
          Object[] values;
  
          @SuppressWarnings("unchecked")
          ZipCoordinator(MaybeObserver<? super R> observer, int n, Function<? super Object[], ? extends R> zipper) {
              super(n);
              this.downstream = observer;
              this.zipper = zipper;
              ZipMaybeObserver<T>[] o = new ZipMaybeObserver[n];
              for (int i = 0; i < n; i++) {
                  o[i] = new ZipMaybeObserver<>(this, i);
              }
              this.observers = o;
              this.values = new Object[n];
          }
  
          @Override
          public boolean isDisposed() {
              return get() <= 0;
          }
  
          @Override
          public void dispose() {
              if (getAndSet(0) > 0) {
                  for (ZipMaybeObserver<?> d : observers) {
                      d.dispose();
                  }
  
                  values = null;
              }
          }
  
          void innerSuccess(T value, int index) {
              Object[] values = this.values;
              if (values != null) {
                  values[index] = value;
              }
              if (decrementAndGet() == 0) {
                  R v;
  
                  try {
                      v = Objects.requireNonNull(zipper.apply(values), "The zipper returned a null value");
                  } catch (Throwable ex) {
                      Exceptions.throwIfFatal(ex);
                      this.values = null;
                      downstream.onError(ex);
                      return;
                  }
  
                  this.values = null;
                  downstream.onSuccess(v);
              }
          }
  
          void disposeExcept(int index) {
              ZipMaybeObserver<T>[] observers = this.observers;
              int n = observers.length;
              for (int i = 0; i < index; i++) {
                  observers[i].dispose();
              }
              for (int i = index + 1; i < n; i++) {
                  observers[i].dispose();
              }
          }
  
          void innerError(Throwable ex, int index) {
              if (getAndSet(0) > 0) {
                  disposeExcept(index);
                  values = null;
                  downstream.onError(ex);
              } else {
                  RxJavaPlugins.onError(ex);
              }
          }
  
          void innerComplete(int index) {
              if (getAndSet(0) > 0) {
                  disposeExcept(index);
                  values = null;
                  downstream.onComplete();
              }
          }
      }
  
      static final class ZipMaybeObserver<T>
      extends AtomicReference<Disposable>
      implements MaybeObserver<T> {
  
          private static final long serialVersionUID = 3323743579927613702L;
  
          final ZipCoordinator<T, ?> parent;
  
          final int index;
  
          ZipMaybeObserver(ZipCoordinator<T, ?> parent, int index) {
              this.parent = parent;
              this.index = index;
          }
  
          public void dispose() {
              DisposableHelper.dispose(this);
          }
  
          @Override
          public void onSubscribe(Disposable d) {
              DisposableHelper.setOnce(this, d);
          }
  
          @Override
          public void onSuccess(T value) {
              parent.innerSuccess(value, index);
          }
  
          @Override
          public void onError(Throwable e) {
              parent.innerError(e, index);
          }
  
          @Override
          public void onComplete() {
              parent.innerComplete(index);
          }
      }
  
      final class SingletonArrayFunc implements Function<T, R> {
          @Override
          public R apply(T t) throws Throwable {
              return Objects.requireNonNull(zipper.apply(new Object[] { t }), "The zipper returned a null value");
          }
      }
  }
  