initial

1 files changed, 66 insertions, 0 deletions

diff --git a/sources/scala/collection/immutable/TreeSet.scala b/sources/scala/collection/immutable/TreeSet.scala
new file mode 100644
index 0000000000..bf085990c2
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+++ b/sources/scala/collection/immutable/TreeSet.scala
@@ -0,0 +1,66 @@
+package scala.collection.immutable;
+
+/** A set that uses TreeMap.
+*/
+
+class TreeSet[A](order: Order[A]) with Set[A] {
+
+  protected val map = new TreeMap[ A, boolean ]( order );
+
+  /** Returns the number of elements in this set.
+  *
+  *  @return number of set elements.
+  */
+  def size: Int = map.size;
+
+  /** 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 = map.get(elem) match {
+    case Some(_) => true;
+    case _ => false;
+  }
+
+  /** This method creates a new set with an additional element.
+  */
+  def +(elem: A): TreeSet[A] = new TreeSet(order) {
+    override val map = TreeSet.this.map.update( elem, true );
+  }
+
+  /** <code>-</code> can be used to remove a single element from
+  *  a set.
+  */
+  def -(elem: A): TreeSet[A] = new TreeSet(order) {
+    override val map = TreeSet.this.map - elem ;
+  }
+
+  /** Creates a new iterator over all elements contained in this
+  *  object.
+  *
+  *  @return the new iterator
+  */
+  def elements: Iterator[A] = map.elements.map {
+    x:Pair[A,boolean] => x._1
+  };
+
+  /** Transform this set into a list of all elements.
+  *
+  *  @return  a list which enumerates all elements of this set.
+  */
+  override def toList: List[A] = elements.toList;
+
+  /** Compares two sets for equality.
+  *   Two set are equal iff they contain the same elements.
+  */
+  override def equals(obj: Any): Boolean =
+    if (obj.isInstanceOf[scala.collection.Set[A]]) {
+      val that = obj.asInstanceOf[scala.collection.Set[A]];
+      if (size != that.size) false else toList.forall(that.contains);
+    } else
+      false;
+
+  override def hashCode(): Int = map.hashCode();
+
+}