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scala.collection.generic.SequenceViewTemplate.scala Maven / Gradle / Ivy
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection.generic
import scala.collection._
import Sequence.fill
import TraversableView.NoBuilder
/** A non-strict projection of an iterable.
* @author Sean McDirmid
* @author Martin Odersky
* @version 2.8
*/
trait SequenceViewTemplate[+A,
+Coll <: Sequence[_],
+This <: SequenceView[A, Coll] with SequenceViewTemplate[A, Coll, This]]
extends Sequence[A] with SequenceTemplate[A, This] with IterableView[A, Coll] with IterableViewTemplate[A, Coll, This]
{ self =>
trait Transformed[+B] extends SequenceView[B, Coll] with super.Transformed[B] {
override def length: Int
override def apply(idx: Int): B
}
trait Sliced extends Transformed[A] with super.Sliced {
override def length = ((until min self.length) - from) max 0
override def apply(idx: Int): A =
if (idx + from < until) self.apply(idx + from)
else throw new IndexOutOfBoundsException(idx.toString)
}
trait Mapped[B] extends Transformed[B] with super.Mapped[B] {
override def length = self.length
override def apply(idx: Int): B = mapping(self apply idx)
}
trait FlatMapped[B] extends Transformed[B] with super.FlatMapped[B] {
protected[this] lazy val index = {
val index = new Array[Int](self.length + 1)
index(0) = 0
for (i <- 0 until self.length)
index(i + 1) = index(i) + mapping(self(i)).size
index
}
protected[this] def findRow(idx: Int, lo: Int, hi: Int): Int = {
val mid = (lo + hi) / 2
if (idx < index(mid)) findRow(idx, lo, mid - 1)
else if (idx >= index(mid + 1)) findRow(idx, mid + 1, hi)
else mid
}
override def length = index(self.length)
override def apply(idx: Int) = {
val row = findRow(idx, 0, self.length - 1)
mapping(self(row)).toSequence(idx - index(row))
}
}
trait Appended[B >: A] extends Transformed[B] with super.Appended[B] {
lazy val restSeq = rest.toSequence
override def length = self.length + restSeq.length
override def apply(idx: Int) =
if (idx < self.length) self(idx) else restSeq(idx - self.length)
}
trait Filtered extends Transformed[A] with super.Filtered {
protected[this] lazy val index = {
var len = 0
val arr = new Array[Int](self.length)
for (i <- 0 until self.length)
if (pred(self(i))) {
arr(len) = i
len += 1
}
arr take len
}
override def length = index.length
override def apply(idx: Int) = self(index(idx))
}
trait TakenWhile extends Transformed[A] with super.TakenWhile {
protected[this] lazy val len = self prefixLength pred
override def length = len
override def apply(idx: Int) =
if (idx < len) self(idx)
else throw new IndexOutOfBoundsException(idx.toString)
}
trait DroppedWhile extends Transformed[A] with super.DroppedWhile {
protected[this] lazy val start = self prefixLength pred
override def length = self.length - start
override def apply(idx: Int) =
if (idx >= 0) self(idx + start)
else throw new IndexOutOfBoundsException(idx.toString)
}
trait Reversed extends Transformed[A] {
override def iterator: Iterator[A] = self.reverseIterator
override def length: Int = self.length
override def apply(idx: Int): A = self.apply(length - 1 - idx)
override def stringPrefix = super.stringPrefix+"R"
}
trait Patched[B >: A] extends Transformed[B] {
protected[this] val from: Int
protected[this] val patch: Sequence[B]
protected[this] val replaced: Int
private lazy val plen = patch.length
override def iterator: Iterator[B] = self.iterator patch (from, patch.iterator, replaced)
override def length: Int = self.length + plen - replaced
override def apply(idx: Int): B =
if (idx < from) self.apply(idx)
else if (idx < from + plen) patch.apply(idx - from)
else self.apply(idx - plen + replaced)
override def stringPrefix = super.stringPrefix+"P"
}
trait Zipped[B] extends Transformed[(A, B)] {
protected[this] val other: Sequence[B]
override def iterator: Iterator[(A, B)] = self.iterator zip other.iterator
override def length = self.length min other.length
override def apply(idx: Int): (A, B) = (self.apply(idx), other.apply(idx))
override def stringPrefix = super.stringPrefix+"Z"
}
/** Boilerplate method, to override in each subclass
* This method could be eliminated if Scala had virtual classes
*/
protected override def newAppended[B >: A](that: Traversable[B]): Transformed[B] = new Appended[B] { val rest = that }
protected override def newMapped[B](f: A => B): Transformed[B] = new Mapped[B] { val mapping = f }
protected override def newFlatMapped[B](f: A => Traversable[B]): Transformed[B] = new FlatMapped[B] { val mapping = f }
protected override def newFiltered(p: A => Boolean): Transformed[A] = new Filtered { val pred = p }
protected override def newSliced(_from: Int, _until: Int): Transformed[A] = new Sliced { val from = _from; val until = _until }
protected override def newDroppedWhile(p: A => Boolean): Transformed[A] = new DroppedWhile { val pred = p }
protected override def newTakenWhile(p: A => Boolean): Transformed[A] = new TakenWhile { val pred = p }
protected def newReversed: Transformed[A] = new Reversed { }
protected def newPatched[B >: A](_from: Int, _patch: Sequence[B], _replaced: Int): Transformed[B] = new Patched[B] {
val from = _from; val patch = _patch; val replaced = _replaced
}
protected def newZipped[B](that: Sequence[B]): Transformed[(A, B)] = new Zipped[B] {
val other = that
}
override def reverse: This = newReversed.asInstanceOf[This]
override def patch[B >: A, That](from: Int, patch: Sequence[B], replaced: Int)(implicit bf: BuilderFactory[B, That, This]): That = {
newPatched(from, patch, replaced).asInstanceOf[That]
// was: val b = bf(thisCollection)
// if (b.isInstanceOf[NoBuilder[_]]) newPatched(from, patch, replaced).asInstanceOf[That]
// else super.patch[B, That](from, patch, replaced)(bf)
}
override def padTo[B >: A, That](len: Int, elem: B)(implicit bf: BuilderFactory[B, That, This]): That =
patch(length, fill(len - length)(elem), 0)
override def zip[A1 >: A, B, That](that: Sequence[B])(implicit bf: BuilderFactory[(A1, B), That, This]): That = {
newZipped(that).asInstanceOf[That]
// was: val b = bf(thisCollection)
// if (b.isInstanceOf[NoBuilder[_]]) newZipped(that).asInstanceOf[That]
// else super.zip[A1, B, That](that)(bf)
}
override def zipWithIndex[A1 >: A, That](implicit bf: BuilderFactory[(A1, Int), That, This]): That =
zip[A1, Int, That](Sequence.range(0, length))(bf)
override def zipAll[B, A1 >: A, That](that: Sequence[B], thisElem: A1, thatElem: B)(implicit bf: BuilderFactory[(A1, B), That, This]): That =
self.padTo(that.length, thisElem).zip(that.padTo(this.length, thatElem))(bf.asInstanceOf[BuilderFactory[(A1, B), That, Any]])
}
