An attempt at reintegrating MapProxy.

1 files changed, 47 insertions, 0 deletions

diff --git a/src/library/scala/collection/immutable/MapProxy.scala b/src/library/scala/collection/immutable/MapProxy.scala
new file mode 100644
index 0000000000..b6a2b2a364
--- /dev/null
+++ b/src/library/scala/collection/immutable/MapProxy.scala
@@ -0,0 +1,47 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003-2009, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+
+// $Id$
+
+
+package scala.collection.immutable
+
+import generic.MapProxyTemplate
+
+/** <p>
+ *    This is a simple wrapper class for <a href="Map.html"
+ *    target="contentFrame"><code>scala.collection.mutable.Map</code></a>.
+ *  </p>
+ *  <p>
+ *    It is most useful for assembling customized map abstractions
+ *    dynamically using object composition and forwarding.
+ *  </p>
+ *
+ *  @author  Matthias Zenger, Martin Odersky
+ *  @version 2.0, 31/12/2006
+ */
+
+trait MapProxy[A, +B] extends immutable.Map[A, B] with MapProxyTemplate[A, B, immutable.Map[A, B]]
+{
+  private def newProxy[B1 >: B](newSelf: immutable.Map[A, B1]): MapProxy[A, B1] =
+    new MapProxy[A, B1] { val self = newSelf }
+
+  override def empty = newProxy(immutable.Map[A, B]())
+  override def updated [B1 >: B](key: A, value: B1) = newProxy(self.updated(key, value))
+
+  override def + [B1 >: B](kv: (A, B1)): Map[A, B1] = newProxy(self + kv)
+  override def + [B1 >: B] (elem1: (A, B1), elem2: (A, B1), elems: (A, B1) *) =
+    newProxy(self.+(elem1, elem2, elems: _*))
+  override def -(key: A) = newProxy(self - key)
+
+  // error: method ++ overrides nothing  -- ??
+  // override def ++[B1 >: B](elems: Traversable[(A, B1)]) = super.++(elems)
+  // override def ++[B1 >: B] (iter: Iterator[(A, B1)]): immutable.Map[A, B1] =
+  override def filterNot(p: ((A, B)) => Boolean) = newProxy(self.filterNot(p))
+  override def update[B1 >: B](key: A, value: B1) = newProxy(self.update(key, value))
+}