monix.reactive.internal.operators.SearchByOrderOperator.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 cats.Order
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
/**
* Common implementation for `minF`, `minByF`, `maxF`, `maxByF`.
*/
private[reactive] abstract class SearchByOrderOperator[A, K](key: A => K)(implicit B: Order[K]) extends Operator[A, A] {
def shouldCollect(key: K, current: K): Boolean
final def apply(out: Subscriber[A]): Subscriber.Sync[A] =
new Subscriber.Sync[A] {
implicit val scheduler = out.scheduler
private[this] var isDone = false
private[this] var minValue: A = _
private[this] var minValueU: K = _
private[this] var hasValue = false
def onNext(elem: A): Ack = {
try {
if (!hasValue) {
hasValue = true
minValue = elem
minValueU = key(elem)
} else {
val m = key(elem)
if (shouldCollect(m, minValueU)) {
minValue = elem
minValueU = m
}
}
Continue
} catch {
case ex if NonFatal(ex) =>
onError(ex)
Stop
}
}
def onError(ex: Throwable): Unit =
if (!isDone) {
isDone = true
out.onError(ex)
}
def onComplete(): Unit =
if (!isDone) {
isDone = true
if (!hasValue)
out.onComplete()
else {
out.onNext(minValue)
out.onComplete()
}
}
}
}
private[reactive] final class MinOperator[A](implicit A: Order[A]) extends SearchByOrderOperator[A, A](identity)(A) {
def shouldCollect(key: A, current: A): Boolean =
A.compare(key, current) < 0
}
private[reactive] final class MinByOperator[A, K](f: A => K)(implicit K: Order[K])
extends SearchByOrderOperator[A, K](f)(K) {
def shouldCollect(key: K, current: K): Boolean =
K.compare(key, current) < 0
}
private[reactive] final class MaxOperator[A](implicit A: Order[A]) extends SearchByOrderOperator[A, A](identity)(A) {
def shouldCollect(key: A, current: A): Boolean =
A.compare(key, current) > 0
}
private[reactive] final class MaxByOperator[A, K](f: A => K)(implicit K: Order[K])
extends SearchByOrderOperator[A, K](f)(K) {
def shouldCollect(key: K, current: K): Boolean =
K.compare(key, current) > 0
}