/*
 * Copyright (c) 2011-2017 Pivotal Software Inc, All Rights Reserved.
 *
 * 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
 *
 *       https://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 reactor.core.publisher;

import org.reactivestreams.Publisher;

import reactor.core.CorePublisher;
import reactor.core.CoreSubscriber;
import reactor.core.Scannable;
import reactor.util.annotation.Nullable;

A decorating Mono Publisher that exposes Mono API over an arbitrary Publisher Useful to create operators which return a Mono.
Type parameters:
/** * A decorating {@link Mono} {@link Publisher} that exposes {@link Mono} API over an * arbitrary {@link Publisher} Useful to create operators which return a {@link Mono}. * * @param <I> delegate {@link Publisher} type * @param <O> produced type */
abstract class InternalMonoOperator<I, O> extends MonoOperator<I, O> implements Scannable, OptimizableOperator<O, I> { @Nullable final OptimizableOperator<?, I> optimizableOperator; protected InternalMonoOperator(Mono<? extends I> source) { super(source); if (source instanceof OptimizableOperator) { @SuppressWarnings("unchecked") OptimizableOperator<?, I> optimSource = (OptimizableOperator<?, I>) source; this.optimizableOperator = optimSource; } else { this.optimizableOperator = null; } } @Override @SuppressWarnings("unchecked") public final void subscribe(CoreSubscriber<? super O> subscriber) { OptimizableOperator operator = this; try { while (true) { subscriber = operator.subscribeOrReturn(subscriber); if (subscriber == null) { // null means "I will subscribe myself", returning... return; } OptimizableOperator newSource = operator.nextOptimizableSource(); if (newSource == null) { operator.source().subscribe(subscriber); return; } operator = newSource; } } catch (Throwable e) { Operators.reportThrowInSubscribe(subscriber, e); return; } } @Nullable public abstract CoreSubscriber<? super I> subscribeOrReturn(CoreSubscriber<? super O> actual) throws Throwable; @Override public final CorePublisher<? extends I> source() { return source; } @Override public final OptimizableOperator<?, ? extends I> nextOptimizableSource() { return optimizableOperator; } }