Reverts r20311 since I'm not seeing what's goin...

Reverts r20311 since I'm not seeing what's going on in #2876 and the
optimization can wait.

1 files changed, 16 insertions, 7 deletions

diff --git a/src/library/scala/collection/TraversableViewLike.scala b/src/library/scala/collection/TraversableViewLike.scala
index 7f4d0ebd71..84c33296db 100644
--- a/src/library/scala/collection/TraversableViewLike.scala
+++ b/src/library/scala/collection/TraversableViewLike.scala
@@ -33,9 +33,7 @@ import TraversableView.NoBuilder
 trait TraversableViewLike[+A,
                           +Coll,
                           +This <: TraversableView[A, Coll] with TraversableViewLike[A, Coll, This]]
-  extends Traversable[A]
-  with TraversableLike[A, This]
-  with views.TraversableTransformations[A, Coll, This] {
+  extends Traversable[A] with TraversableLike[A, This] {
 self =>
 
   override protected[this] def newBuilder: Builder[A, This] =
@@ -43,16 +41,16 @@ self =>
 
   protected def underlying: Coll
 
-  trait Transformed[+B] extends views.TraversableLike[B, Coll] {
-    lazy val underlying = self.underlying
-  }
-
   def force[B >: A, That](implicit bf: CanBuildFrom[Coll, B, That]) = {
     val b = bf(underlying)
     b ++= this
     b.result()
   }
 
+  trait Transformed[+B] extends TraversableView[B, Coll] {
+    lazy val underlying = self.underlying
+  }
+
   /** pre: from >= 0
    */
   trait Sliced extends Transformed[A] {
@@ -133,6 +131,17 @@ self =>
     override def stringPrefix = self.stringPrefix+"D"
   }
 
+  /** Boilerplate method, to override in each subclass
+   *  This method could be eliminated if Scala had virtual classes
+   */
+  protected def newAppended[B >: A](that: Traversable[B]): Transformed[B] = new Appended[B] { val rest = that }
+  protected def newMapped[B](f: A => B): Transformed[B] = new Mapped[B] { val mapping = f }
+  protected def newFlatMapped[B](f: A => Traversable[B]): Transformed[B] = new FlatMapped[B] { val mapping = f }
+  protected def newFiltered(p: A => Boolean): Transformed[A] = new Filtered { val pred = p }
+  protected def newSliced(_from: Int, _until: Int): Transformed[A] = new Sliced { val from = _from; val until = _until }
+  protected def newDroppedWhile(p: A => Boolean): Transformed[A] = new DroppedWhile { val pred = p }
+  protected def newTakenWhile(p: A => Boolean): Transformed[A] = new TakenWhile { val pred = p }
+
   override def ++[B >: A, That](that: Traversable[B])(implicit bf: CanBuildFrom[This, B, That]): That = {
     newAppended(that).asInstanceOf[That]
 // was:    if (bf.isInstanceOf[ByPassCanBuildFrom]) newAppended(that).asInstanceOf[That]