1 files changed, 69 insertions, 0 deletions
diff --git a/src/library/scala/collection/immutable/TreeSet.scala b/src/library/scala/collection/immutable/TreeSet.scala
new file mode 100644
index 0000000000..bb3099e007
--- /dev/null
+++ b/src/library/scala/collection/immutable/TreeSet.scala
@@ -0,0 +1,69 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003-2005, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |                                         **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+
+// $Id$
+
+package scala.collection.immutable;
+
+
+/** This class implements immutable sets using a tree.
+ *
+ *  @author  Matthias Zenger
+ *  @author  Burak Emir
+ *  @version 1.1, 03/05/2004
+ */
+//[serializable]
+class TreeSet[A <% Ordered[A]]() extends Tree[A, A] with Set[A] with java.io.Serializable {
+
+    override protected type This = TreeSet[A];
+    override protected def getThis: This = this;
+
+    protected def New(sz: Int, t: aNode): This = new TreeSet[A] {
+        override def size = sz;
+        override protected def tree: aNode = t;
+    }
+
+    /** Checks if this set contains element <code>elem</code>.
+     *
+     *  @param  elem    the element to check for membership.
+     *  @return true, iff <code>elem</code> is contained in this set.
+     */
+    def contains(elem: A): Boolean = !findValue(elem).isEmpty;
+
+    /** This method creates a new set with an additional element.
+     */
+    def +(elem: A): TreeSet[A] = updateOrAdd(elem, elem);
+
+    /** <code>-</code> can be used to remove a single element from
+     *  a set.
+     */
+    def -(elem: A): TreeSet[A] = deleteAny(elem);
+
+    /** Creates a new iterator over all elements contained in this
+     *  object.
+     *
+     *  @return the new iterator
+     */
+    def elements: Iterator[A] = entries;
+
+    /** Transform this set into a list of all elements.
+     *
+     *  @return  a list which enumerates all elements of this set.
+     */
+    override def toList: List[A] =
+      tree.toList(scala.Nil) map (._2);
+
+    /** Compares two sets for equality.
+     *  Two set are equal iff they contain the same elements.
+     */
+    override def equals(obj: Any): Boolean =
+        obj.isInstanceOf[scala.collection.Set[A]] && {
+          val that = obj.asInstanceOf[scala.collection.Set[A]];
+          (size == that.size) && toList.forall(that.contains);
+        }
+}