Use RedBlack.iterator to create iterators for TreeSet/TreeMap.

This turns iterator creation from an O(n) operation into an
O(log n) operation. Unfortunately, it halves actual iteration
speed (consuming the iterator fully), probably due to the many
by-name closures that are needed.

2 files changed, 2 insertions, 2 deletions

diff --git a/src/library/scala/collection/immutable/TreeMap.scala b/src/library/scala/collection/immutable/TreeMap.scala
index ef0eac3701..2fd5208991 100644
--- a/src/library/scala/collection/immutable/TreeMap.scala
+++ b/src/library/scala/collection/immutable/TreeMap.scala
@@ -153,7 +153,7 @@ class TreeMap[A, +B](override val size: Int, t: RedBlack[A]#Tree[B])(implicit va
    *
    *  @return the new iterator
    */
-  def iterator: Iterator[(A, B)] = tree.toStream.iterator
+  def iterator: Iterator[(A, B)] = tree.iterator
 
   override def toStream: Stream[(A, B)] = tree.toStream
 
diff --git a/src/library/scala/collection/immutable/TreeSet.scala b/src/library/scala/collection/immutable/TreeSet.scala
index 8b90ece143..05f27d0d93 100644
--- a/src/library/scala/collection/immutable/TreeSet.scala
+++ b/src/library/scala/collection/immutable/TreeSet.scala
@@ -107,7 +107,7 @@ class TreeSet[A](override val size: Int, t: RedBlack[A]#Tree[Unit])
    *
    *  @return the new iterator
    */
-  def iterator: Iterator[A] = tree.toStream.iterator map (_._1)
+  def iterator: Iterator[A] = tree.iterator map (_._1)
 
   override def toStream: Stream[A] = tree.toStream map (_._1)