/*  Title:      Pure/System/event_bus.scala

     Module:     PIDE

     Author:     Makarius

 Generic event bus with multiple receiving actors.

 */

 package isabelle

 import scala.actors.Actor, Actor._

 import scala.collection.mutable.ListBuffer

 class Event_Bus[Event]

 {

   /* receivers */

   private val receivers = new ListBuffer[Actor]

   def += (r: Actor) { synchronized { receivers += r } }

   def + (r: Actor): Event_Bus[Event] = { this += r; this }

   def += (f: Event => Unit) {

     this += actor { loop { react { case x => f(x.asInstanceOf[Event]) } } }

   }

   def + (f: Event => Unit): Event_Bus[Event] = { this += f; this }

   def -= (r: Actor) { synchronized { receivers -= r } }

   def - (r: Actor) = { this -= r; this }

   /* event invocation */

   def event(x: Event) { synchronized { receivers.foreach(_ ! x) } }

 }