1 files changed, 31 insertions, 0 deletions
diff --git a/src/library/scala/collection/mutable/RevertableHistory.scala b/src/library/scala/collection/mutable/RevertableHistory.scala
new file mode 100644
index 0000000000..c9bb1ef6d1
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+++ b/src/library/scala/collection/mutable/RevertableHistory.scala
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+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003, LAMP/EPFL                  **
+**  __\ \/ /__/ __ |/ /__/ __ |                                         **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+** $Id$
+\*                                                                      */
+
+package scala.collection.mutable;
+
+
+/** A revertable history is a <code>History</code> object which supports
+ *  an undo operation. Type variable <code>A</code> refers to the type
+ *  of the published events, <code>B</code> denotes the publisher type.
+ *  Type <code>B</code> is typically a subtype of <code>Publisher</code>.
+ *
+ *  @author  Matthias Zenger
+ *  @version 1.0, 08/07/2003
+ */
+[serializable]
+class RevertableHistory[A <: Undoable, B] extends History[A, B] with Undoable {
+
+    /** Rollback the full history.
+     */
+    def undo: Unit = {
+        val old = log.toList.reverse;
+        clear;
+        old.foreach { case Pair(sub, event) => event.undo; }
+    }
+}