monix.reactive.internal.operators.DropByPredicateOperator.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.{Continue, Stop}
import scala.util.control.NonFatal
import monix.reactive.Observable.Operator
import monix.reactive.observers.Subscriber
import scala.concurrent.Future
private[reactive] final class DropByPredicateOperator[A](p: A => Boolean, inclusive: Boolean) extends Operator[A, A] {
def apply(out: Subscriber[A]): Subscriber[A] =
new Subscriber[A] {
implicit val scheduler = out.scheduler
private[this] var continueDropping = true
private[this] var isDone = false
def onNext(elem: A): Future[Ack] = {
if (continueDropping) {
// See Section 6.4. in the Rx Design Guidelines:
// Protect calls to user code from within an operator
var streamError = true
try {
val isStillInvalid = p(elem)
streamError = false
if (isStillInvalid)
Continue
else {
continueDropping = false
if (inclusive)
Continue
else
out.onNext(elem)
}
} catch {
case NonFatal(ex) if streamError =>
onError(ex)
Stop
}
} else
out.onNext(elem)
}
def onError(ex: Throwable): Unit =
if (!isDone) {
isDone = true
out.onError(ex)
}
def onComplete(): Unit =
if (!isDone) {
isDone = true
out.onComplete()
}
}
}