monix.reactive.internal.operators.CollectWhileOperator.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.operators
import monix.execution.Ack
import monix.execution.Ack.Stop
import scala.util.control.NonFatal
import monix.reactive.Observable.Operator
import monix.reactive.internal.operators.CollectOperator.{checkFallback, isDefined}
import monix.reactive.observers.Subscriber
import scala.concurrent.Future
private[reactive] final class CollectWhileOperator[-A, +B](pf: PartialFunction[A, B]) extends Operator[A, B] {
def apply(out: Subscriber[B]): Subscriber[A] =
new Subscriber[A] {
implicit val scheduler = out.scheduler
private[this] var isActive = true
def onNext(elem: A): Future[Ack] = {
if (!isActive) Stop
else {
// Protects calls to user code from within an operator
var streamError = true
try {
val next = pf.applyOrElse(elem, checkFallback[B])
if (isDefined(next)) {
streamError = false
out.onNext(next)
} else {
isActive = false
out.onComplete()
Stop
}
} catch {
case NonFatal(ex) if streamError =>
onError(ex)
Stop
}
}
}
def onComplete() =
if (isActive) {
isActive = false
out.onComplete()
}
def onError(ex: Throwable) =
if (isActive) {
isActive = false
out.onError(ex)
}
}
}
private object CollectWhileOperator extends (Any => Any) {
/** In the case a partial function is not defined, return a magic fallback value. */
def checkFallback[B]: Any => B = this.asInstanceOf[Any => B]
/** Indicates whether the result is the magic fallback value. */
def isDefined(result: Any): Boolean = result.asInstanceOf[AnyRef] ne this
/** Always returns `this`, used as the magic fallback value. */
override def apply(elem: Any): Any = this
}