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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2011, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala.collection
import generic._
import mutable.{ Builder, ArrayBuffer }
import TraversableView.NoBuilder
import annotation.migration
private[collection] trait GenTraversableViewLike[+A,
+Coll,
+This <: GenTraversableView[A, Coll] with GenTraversableViewLike[A, Coll, This]]
extends GenTraversable[A] with GenTraversableLike[A, This] {
self =>
def force[B >: A, That](implicit bf: CanBuildFrom[Coll, B, That]): That
protected def underlying: Coll
protected[this] def viewIdentifier: String
protected[this] def viewIdString: String
def viewToString = stringPrefix + viewIdString + "(...)"
/** The implementation base trait of this view.
* This trait and all its subtraits has to be re-implemented for each
* ViewLike class.
*/
trait Transformed[+B] extends GenTraversableView[B, Coll] {
def foreach[U](f: B => U): Unit
lazy val underlying = self.underlying
final override protected[this] def viewIdString = self.viewIdString + viewIdentifier
override def stringPrefix = self.stringPrefix
override def toString = viewToString
}
trait EmptyView extends Transformed[Nothing] {
final override def isEmpty = true
final override def foreach[U](f: Nothing => U): Unit = ()
}
/** A fall back which forces everything into a vector and then applies an operation
* on it. Used for those operations which do not naturally lend themselves to a view
*/
trait Forced[B] extends Transformed[B] {
protected[this] val forced: GenSeq[B]
def foreach[U](f: B => U) = forced foreach f
final override protected[this] def viewIdentifier = "C"
}
trait Sliced extends Transformed[A] {
protected[this] val endpoints: SliceInterval
protected[this] def from = endpoints.from
protected[this] def until = endpoints.until
// protected def newSliced(_endpoints: SliceInterval): Transformed[A] =
// self.newSliced(endpoints.recalculate(_endpoints))
def foreach[U](f: A => U) {
var index = 0
for (x <- self) {
if (from <= index) {
if (until <= index) return
f(x)
}
index += 1
}
}
final override protected[this] def viewIdentifier = "S"
}
trait Mapped[B] extends Transformed[B] {
protected[this] val mapping: A => B
def foreach[U](f: B => U) {
for (x <- self)
f(mapping(x))
}
final override protected[this] def viewIdentifier = "M"
}
trait FlatMapped[B] extends Transformed[B] {
protected[this] val mapping: A => GenTraversableOnce[B]
def foreach[U](f: B => U) {
for (x <- self)
for (y <- mapping(x).seq)
f(y)
}
final override protected[this] def viewIdentifier = "N"
}
trait Appended[B >: A] extends Transformed[B] {
protected[this] val rest: GenTraversable[B]
def foreach[U](f: B => U) {
self foreach f
rest foreach f
}
final override protected[this] def viewIdentifier = "A"
}
trait Filtered extends Transformed[A] {
protected[this] val pred: A => Boolean
def foreach[U](f: A => U) {
for (x <- self)
if (pred(x)) f(x)
}
final override protected[this] def viewIdentifier = "F"
}
trait TakenWhile extends Transformed[A] {
protected[this] val pred: A => Boolean
def foreach[U](f: A => U) {
for (x <- self) {
if (!pred(x)) return
f(x)
}
}
final override protected[this] def viewIdentifier = "T"
}
trait DroppedWhile extends Transformed[A] {
protected[this] val pred: A => Boolean
def foreach[U](f: A => U) {
var go = false
for (x <- self) {
if (!go && !pred(x)) go = true
if (go) f(x)
}
}
final override protected[this] def viewIdentifier = "D"
}
}
|
