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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala.collection
package mutable
import generic._
import TraversableView.NoBuilder
import scala.language.implicitConversions
/** A non-strict view of a mutable `IndexedSeq`.
* $viewInfo
* Some of the operations of this class will yield again a mutable indexed sequence,
* others will just yield a plain indexed sequence of type `collection.IndexedSeq`.
* Because this is a leaf class there is no associated `Like` class.
* @author Martin Odersky
* @version 2.8
* @since 2.8
* @tparam A the element type of the view
* @tparam Coll the type of the underlying collection containing the elements.
*/
trait IndexedSeqView[A, +Coll] extends IndexedSeq[A]
with IndexedSeqOptimized[A, IndexedSeqView[A, Coll]]
with SeqView[A, Coll]
with SeqViewLike[A, Coll, IndexedSeqView[A, Coll]] {
self =>
private[this] type This = IndexedSeqView[A, Coll]
def update(idx: Int, elem: A): Unit
trait Transformed[B] extends IndexedSeqView[B, Coll] with super.Transformed[B] {
def update(idx: Int, elem: B): Unit
override def toString = viewToString
}
/** Explicit instantiation of the `Transformed` trait to reduce class file size in subclasses. */
private[collection] abstract class AbstractTransformed[B] extends super.AbstractTransformed[B] with Transformed[B]
// pre: until <= self.length
trait Sliced extends super.Sliced with Transformed[A] {
override def length = endpoints.width
def update(idx: Int, elem: A) =
if (idx + from < until) self.update(idx + from, elem)
else throw new IndexOutOfBoundsException(idx.toString)
}
trait Filtered extends super.Filtered with Transformed[A] {
def update(idx: Int, elem: A) = self.update(index(idx), elem)
}
trait TakenWhile extends super.TakenWhile with Transformed[A] {
def update(idx: Int, elem: A) =
if (idx < len) self.update(idx, elem)
else throw new IndexOutOfBoundsException(idx.toString)
}
trait DroppedWhile extends super.DroppedWhile with Transformed[A] {
def update(idx: Int, elem: A) =
if (idx >= 0) self.update(idx + start, elem)
else throw new IndexOutOfBoundsException(idx.toString)
}
trait Reversed extends super.Reversed with Transformed[A] {
def update(idx: Int, elem: A) = self.update(self.length - 1 - idx, elem)
}
/** Boilerplate method, to override in each subclass
* This method could be eliminated if Scala had virtual classes
*/
protected override def newFiltered(p: A => Boolean): Transformed[A] = new { val pred = p } with AbstractTransformed[A] with Filtered
protected override def newSliced(_endpoints: SliceInterval): Transformed[A] = new { val endpoints = _endpoints } with AbstractTransformed[A] with Sliced
protected override def newDroppedWhile(p: A => Boolean): Transformed[A] = new { val pred = p } with AbstractTransformed[A] with DroppedWhile
protected override def newTakenWhile(p: A => Boolean): Transformed[A] = new { val pred = p } with AbstractTransformed[A] with TakenWhile
protected override def newReversed: Transformed[A] = new AbstractTransformed[A] with Reversed
private implicit def asThis(xs: Transformed[A]): This = xs.asInstanceOf[This]
override def filter(p: A => Boolean): This = newFiltered(p)
override def init: This = newSliced(SliceInterval(0, self.length - 1))
override def drop(n: Int): This = newSliced(SliceInterval(n, self.length))
override def take(n: Int): This = newSliced(SliceInterval(0, n min self.length))
override def slice(from: Int, until: Int): This = newSliced(SliceInterval(from, until min self.length))
override def dropWhile(p: A => Boolean): This = newDroppedWhile(p)
override def takeWhile(p: A => Boolean): This = newTakenWhile(p)
override def span(p: A => Boolean): (This, This) = (newTakenWhile(p), newDroppedWhile(p))
override def splitAt(n: Int): (This, This) = (take(n), drop(n)) // !!!
override def reverse: This = newReversed
}
/** An object containing the necessary implicit definitions to make
* `SeqView`s work. Its definitions are generally not accessed directly by clients.
*
* Note that the `canBuildFrom` factories yield `SeqView`s, not `IndexedSeqView`s.
* This is intentional, because not all operations yield again a `mutable.IndexedSeqView`.
* For instance, `map` just gives a `SeqView`, which reflects the fact that
* `map` cannot do its work and maintain a pointer into the original indexed sequence.
*/
object IndexedSeqView {
type Coll = TraversableView[_, C] forSome {type C <: Traversable[_]}
implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, SeqView[A, Seq[_]]] =
new CanBuildFrom[Coll, A, SeqView[A, Seq[_]]] {
def apply(from: Coll) = new NoBuilder
def apply() = new NoBuilder
}
implicit def arrCanBuildFrom[A]: CanBuildFrom[TraversableView[_, Array[_]], A, SeqView[A, Array[A]]] =
new CanBuildFrom[TraversableView[_, Array[_]], A, SeqView[A, Array[A]]] {
def apply(from: TraversableView[_, Array[_]]) = new NoBuilder
def apply() = new NoBuilder
}
}
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