japgolly.scalajs.react.extra.Broadcaster.scala Maven / Gradle / Ivy
package japgolly.scalajs.react.extra
import japgolly.scalajs.react.{Callback, CallbackTo}
/**
* Implementation of `Listener`.
* Subclasses can broadcast data of type A via the `broadcast` method.
*/
trait Broadcaster[A] extends Listenable[A] {
/** (A => Callback, Unit) instead of (A => Callback) because unregister is tied to a specific registration, rather
* than the listener fn itself. This allows users to register the same listener multiple times and each
* registration is guaranteed to only correspond to the single registration.
*/
private var _listeners = List.empty[(A => Callback, Unit)]
protected final def listenerIterator: Iterator[A => Callback] =
_listeners.iterator.map(_._1)
override def register(listener: A => Callback) = CallbackTo {
val record = (listener, ())
_listeners ::= record
Callback({_listeners = _listeners.filter(_ ne record)})
}
protected def broadcast(a: A): Callback =
Callback.traverse(_listeners)(_._1(a))
}