monix.reactive.internal.consumers.HeadOptionConsumer.scala Maven / Gradle / Ivy
/*
* Copyright (c) 2014-2020 by The Monix Project Developers.
* See the project homepage at: https://monix.io
*
* 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 monix.reactive.internal.consumers
import monix.execution.Callback
import monix.execution.Ack.Stop
import monix.execution.{Ack, Scheduler}
import monix.execution.cancelables.AssignableCancelable
import monix.reactive.Consumer
import monix.reactive.observers.Subscriber
/** Implementation for [[monix.reactive.Consumer.headOption]] */
private[reactive] final class HeadOptionConsumer[A] extends Consumer.Sync[A, Option[A]] {
override def createSubscriber(
cb: Callback[Throwable, Option[A]],
s: Scheduler): (Subscriber.Sync[A], AssignableCancelable) = {
val out = new Subscriber.Sync[A] {
implicit val scheduler = s
private[this] var isDone = false
def onNext(elem: A): Ack = {
isDone = true
cb.onSuccess(Some(elem))
Stop
}
def onComplete(): Unit =
if (!isDone) {
isDone = true
cb.onSuccess(None)
}
def onError(ex: Throwable): Unit =
if (!isDone) {
isDone = true
cb.onError(ex)
}
}
(out, AssignableCancelable.dummy)
}
}