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.core.Flowable;
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.Supplier;
  import io.reactivex.rxjava3.internal.subscriptions.DeferredScalarSubscription;
  import io.reactivex.rxjava3.plugins.RxJavaPlugins;
  
  import java.util.Objects;
  
  /**
   * Call a Supplier for each incoming Subscriber and signal the returned value or the thrown exception.
   * @param <T> the value type and element type returned by the supplier and the flow
   * @since 3.0.0
   */
  public final class FlowableFromSupplier<T> extends Flowable<T> implements Supplier<T> {
  
      final Supplier<? extends T> supplier;
  
      public FlowableFromSupplier(Supplier<? extends T> supplier) {
          this.supplier = supplier;
      }
  
      @Override
      public void subscribeActual(Subscriber<? super T> s) {
          DeferredScalarSubscription<T> deferred = new DeferredScalarSubscription<>(s);
          s.onSubscribe(deferred);
  
          T t;
          try {
              t = Objects.requireNonNull(supplier.get(), "The supplier returned a null value");
          } catch (Throwable ex) {
              Exceptions.throwIfFatal(ex);
              if (deferred.isCancelled()) {
                  RxJavaPlugins.onError(ex);
              } else {
                  s.onError(ex);
              }
              return;
          }
  
          deferred.complete(t);
      }
  
      @Override
      public T get() throws Throwable {
          return Objects.requireNonNull(supplier.get(), "The supplier returned a null value");
      }
  }
  