Included a generic Subject/Observer implementat...

Included a generic Subject/Observer implementation.

3 files changed, 89 insertions, 0 deletions

diff --git a/sources/scala/MultiMap.scala b/sources/scala/MultiMap.scala
new file mode 100644
index 0000000000..17425036b7
--- /dev/null
+++ b/sources/scala/MultiMap.scala
@@ -0,0 +1,34 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003, LAMP/EPFL                  **
+**  __\ \/ /__/ __ |/ /__/ __ |                                         **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+** $Id$
+\*                                                                      */
+
+package scala;
+
+
+trait MultiMap[A, B] extends MutableMap[A, Set[B]] {
+    protected def makeSet: Set[B] = new HashSet[B];
+
+    def add(key: A, value: B): Unit = get(key) match {
+        case None => val set = makeSet;
+                     set.add(value);
+                     update(key, set);
+        case Some(set) => set.add(value);
+    }
+
+    override def remove(key: A) = super.remove(key);
+
+    override def remove(key: A, value: B) = get(key) match {
+        case None =>
+        case Some(set) => set.remove(value);
+    }
+
+    def exists(key: A, p: B => Boolean): Boolean = get(key) match {
+        case None => false
+        case Some(set) => set.exists(p);
+    }
+}
diff --git a/sources/scala/Publisher.scala b/sources/scala/Publisher.scala
new file mode 100644
index 0000000000..212d64e957
--- /dev/null
+++ b/sources/scala/Publisher.scala
@@ -0,0 +1,37 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003, LAMP/EPFL                  **
+**  __\ \/ /__/ __ |/ /__/ __ |                                         **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+** $Id$
+\*                                                                      */
+
+package scala;
+
+
+/** <tt>Publisher[A, This]</tt> objects publish events of type <tt>A</tt>
+ *  to all registered subscribers.
+ */
+class Publisher[A, This <: Publisher[A, This]]: This {
+    private val filters = new HashMap[Subscriber[A, This], 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.add(sub);
+
+    def activateSubscription(sub: Subscriber[A, This]): Unit = suspended.remove(sub);
+
+    def removeSubscription(sub: Subscriber[A, This]): Unit = filters.remove(sub);
+
+    def removeSubscriptions: Unit = filters.clear;
+
+    protected def publish(event: A): Unit =
+        filters.keys.foreach(sub =>
+            if (filters.exists(sub, (p => p(event)))) sub.update(this, event));
+}
diff --git a/sources/scala/Subscriber.scala b/sources/scala/Subscriber.scala
new file mode 100644
index 0000000000..f41dd3e44d
--- /dev/null
+++ b/sources/scala/Subscriber.scala
@@ -0,0 +1,18 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003, LAMP/EPFL                  **
+**  __\ \/ /__/ __ |/ /__/ __ |                                         **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+** $Id$
+\*                                                                      */
+
+package scala;
+
+
+/** <tt>Subscriber[-A, -B]</tt> objects may subscribe to events of
+ *  type <tt>A</tt> published by an object of type <tt>B</tt>.
+ */
+trait Subscriber[-A, -B] {
+    def update(pub: B, event: A): Unit;
+}