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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2006, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection.mutable
/** <code>Publisher[A,This]</code> objects publish events of type <code>A</code>
* to all registered subscribers. When subscribing, a subscriber may specify
* a filter which can be used to constrain the number of events sent to the
* subscriber. Subscribers may suspend their subscription, or reactivate a
* suspended subscription. Class <code>Publisher</code> is typically used
* as a mixin. The type variable <code>This</code> models self types.
*
* @author Matthias Zenger
* @version 1.0, 08/07/2003
*/
trait Publisher[A, This <: Publisher[A, This]] { self: This =>
private val filters = new HashMap[Subscriber[A, This],
scala.collection.mutable.Set[A => Boolean]]
with MultiMap[Subscriber[A, This], A => Boolean]
private val suspended = new HashSet[Subscriber[A, This]]
def subscribe(sub: Subscriber[A, This]): Unit =
subscribe(sub, event => true)
def subscribe(sub: Subscriber[A, This], filter: A => Boolean): Unit =
filters.add(sub, filter)
def suspendSubscription(sub: Subscriber[A, This]): Unit = suspended += sub
def activateSubscription(sub: Subscriber[A, This]): Unit = suspended -= sub
def removeSubscription(sub: Subscriber[A, This]): Unit = filters -= sub
def removeSubscriptions() { filters.clear }
protected def publish(event: A): Unit =
filters.keys.foreach(sub =>
if (filters.entryExists(sub, p => p(event))) sub.notify(this, event))
}
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