Array combiners implementation changed from arr...

Array combiners implementation changed from array buffers to doubling
unrolled buffers to avoid excessive copying. Still evaluating the
benefits of this.

No review.

1 files changed, 19 insertions, 8 deletions

diff --git a/src/library/scala/collection/immutable/HashMap.scala b/src/library/scala/collection/immutable/HashMap.scala
index 4a7a10c6c1..f6e17e9630 100644
--- a/src/library/scala/collection/immutable/HashMap.scala
+++ b/src/library/scala/collection/immutable/HashMap.scala
@@ -473,14 +473,25 @@ time { mNew.iterator.foreach( p => ()) }
   }
 
   class TrieIterator[A, +B](elems: Array[HashMap[A, B]]) extends Iterator[(A, B)] {
-    private[this] var depth = 0
-    private[this] var arrayStack = new Array[Array[HashMap[A,B]]](6)
-    private[this] var posStack = new Array[Int](6)
-
-    private[this] var arrayD = elems
-    private[this] var posD = 0
-
-    private[this] var subIter: Iterator[(A, B)] = null // to traverse collision nodes
+    protected var depth = 0
+    protected var arrayStack: Array[Array[HashMap[A, B @uncheckedVariance]]] = new Array[Array[HashMap[A,B]]](6)
+    protected var posStack = new Array[Int](6)
+
+    protected var arrayD: Array[HashMap[A, B  @uncheckedVariance]] = elems
+    protected var posD = 0
+
+    protected var subIter: Iterator[(A, B @uncheckedVariance)] = null // to traverse collision nodes
+
+    def dupIterator: TrieIterator[A, B] = {
+      val t = new TrieIterator(elems)
+      t.depth = depth
+      t.arrayStack = arrayStack
+      t.posStack = posStack
+      t.arrayD = arrayD
+      t.posD = posD
+      t.subIter = subIter
+      t
+    }
 
     def hasNext = (subIter ne null) || depth >= 0