monifu.reactive.Subject.scala Maven / Gradle / Ivy
/*
* Copyright (c) 2014-2015 by its authors. Some rights reserved.
* See the project homepage at: http://www.monifu.org
*
* 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 monifu.reactive
import monifu.reactive.observables.LiftOperators2
import scala.concurrent.Future
/**
* A `Subject` is a sort of bridge or proxy that acts both as an
* [[Observer]] and as an [[Observable]] and that must respect the contract of both.
*
* Because it is a `Observer`, it can subscribe to an `Observable` and because it is an `Observable`,
* it can pass through the items it observes by re-emitting them and it can also emit new items.
*
* Useful to build multicast Observables or reusable processing pipelines.
*/
trait Subject[I, +T] extends Observable[T] with Observer[I]
with LiftOperators2[I, T, Subject] { self =>
protected def liftToSelf[U](f: Observable[T] => Observable[U]): Subject[I, U] =
new Subject[I,U] {
def onNext(elem: I): Future[Ack] = self.onNext(elem)
def onError(ex: Throwable): Unit = self.onError(ex)
def onComplete(): Unit = self.onComplete()
private[this] val lifted = f(self)
def onSubscribe(subscriber: Subscriber[U]): Unit =
lifted.onSubscribe(subscriber)
}
}