path: root/src/library/scala/collection/IterableViewLike.scala

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2010, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

// $Id$


package scala.collection

import generic._
import collection.immutable.Stream
import TraversableView.NoBuilder

/** A template trait for a non-strict view of an iterable.
 *
 *  @author Martin Odersky
 *  @version 2.8
 *  @since   2.8
 */
trait IterableViewLike[+A,
                       +Coll,
                       +This <: IterableView[A, Coll] with IterableViewLike[A, Coll, This]]
  extends Iterable[A]
      with IterableLike[A, This]
      with TraversableView[A, Coll]
      with TraversableViewLike[A, Coll, This]
      with views.IterableTransformations[A, Coll, This]
{ self =>

  trait Transformed[+B] extends views.IterableLike[B, Coll] with super.Transformed[B]

  trait Sliced extends Transformed[A] with super.Sliced {
    override def iterator = self.iterator slice (from, until)
  }

  trait Mapped[B] extends Transformed[B] with super.Mapped[B] {
    override def iterator = self.iterator map mapping
  }

  trait FlatMapped[B] extends Transformed[B] with super.FlatMapped[B] {
    override def iterator = self.iterator flatMap (mapping(_).toIterable.iterator)
  }

  trait Appended[B >: A] extends Transformed[B] with super.Appended[B] {
    override def iterator = self.iterator ++ rest.toIterable.iterator
  }

  trait Filtered extends Transformed[A] with super.Filtered {
    override def iterator = self.iterator filter pred
  }

  trait TakenWhile extends Transformed[A] with super.TakenWhile {
    override def iterator = self.iterator takeWhile pred
  }

  trait DroppedWhile extends Transformed[A] with super.DroppedWhile {
    override def iterator = self.iterator dropWhile pred
  }

  trait Zipped[B] extends Transformed[(A, B)] {
    protected[this] val other: Iterable[B]
    override def iterator: Iterator[(A, B)] = self.iterator zip other.iterator
    override def stringPrefix = self.stringPrefix+"Z"
  }

  trait ZippedAll[A1 >: A, B] extends Transformed[(A1, B)] {
    protected[this] val other: Iterable[B]
    protected[this] val thisElem: A1
    protected[this] val thatElem: B
    override def iterator: Iterator[(A1, B)] =
      self.iterator.zipAll(other.iterator, thisElem, thatElem)
  }

  override def zip[A1 >: A, B, That](that: Iterable[B])(implicit bf: CanBuildFrom[This, (A1, B), That]): That = {
    newZipped(that).asInstanceOf[That]
// was:    val b = bf(repr)
//    if (b.isInstanceOf[NoBuilder[_]]) newZipped(that).asInstanceOf[That]
//    else super.zip[A1, B, That](that)(bf)
  }

  override def zipWithIndex[A1 >: A, That](implicit bf: CanBuildFrom[This, (A1, Int), That]): That =
    zip[A1, Int, That](Stream from 0)(bf)

  override def zipAll[B, A1 >: A, That](that: Iterable[B], thisElem: A1, thatElem: B)(implicit bf: CanBuildFrom[This, (A1, B), That]): That =
    newZippedAll(that, thisElem, thatElem).asInstanceOf[That]

  override def stringPrefix = "IterableView"
}