Created team of private[collection] abstract cl...

Created team of private[collection] abstract classes and traits in
scala.collection.views. Factored boilerplate and base Transformed traits
out of *ViewLike classes. Executive summary and motivation:

  4812029 Dec 23 09:47 scala-library.jar // before
  4604150 Dec 23 09:24 scala-library.jar // after

Direct size savings of 4.5%.  Review by odersky.

1 files changed, 7 insertions, 16 deletions

diff --git a/src/library/scala/collection/TraversableViewLike.scala b/src/library/scala/collection/TraversableViewLike.scala
index 84c33296db..7f4d0ebd71 100644
--- a/src/library/scala/collection/TraversableViewLike.scala
+++ b/src/library/scala/collection/TraversableViewLike.scala
@@ -33,7 +33,9 @@ import TraversableView.NoBuilder
 trait TraversableViewLike[+A,
                           +Coll,
                           +This <: TraversableView[A, Coll] with TraversableViewLike[A, Coll, This]]
-  extends Traversable[A] with TraversableLike[A, This] {
+  extends Traversable[A]
+  with TraversableLike[A, This]
+  with views.TraversableTransformations[A, Coll, This] {
 self =>
 
   override protected[this] def newBuilder: Builder[A, This] =
@@ -41,16 +43,16 @@ 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] {
@@ -131,17 +133,6 @@ 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]