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Standard library for the Scala Programming Language
/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala
package collection.mutable
import scala.collection.Stepper.EfficientSplit
import scala.collection.generic.DefaultSerializable
import scala.collection.mutable.{RedBlackTree => RB}
import scala.collection.{SortedIterableFactory, SortedSetFactoryDefaults, Stepper, StepperShape, StrictOptimizedIterableOps, StrictOptimizedSortedSetOps, mutable}
/**
* A mutable sorted set implemented using a mutable red-black tree as underlying data structure.
*
* @param ordering the implicit ordering used to compare objects of type `A`.
* @tparam A the type of the keys contained in this tree set.
*
* @define Coll mutable.TreeSet
* @define coll mutable tree set
*/
// Original API designed in part by Lucien Pereira
sealed class TreeSet[A] private (private val tree: RB.Tree[A, Null])(implicit val ordering: Ordering[A])
extends AbstractSet[A]
with SortedSet[A]
with SortedSetOps[A, TreeSet, TreeSet[A]]
with StrictOptimizedIterableOps[A, Set, TreeSet[A]]
with StrictOptimizedSortedSetOps[A, TreeSet, TreeSet[A]]
with SortedSetFactoryDefaults[A, TreeSet, Set]
with DefaultSerializable {
if (ordering eq null)
throw new NullPointerException("ordering must not be null")
/**
* Creates an empty `TreeSet`.
* @param ord the implicit ordering used to compare objects of type `A`.
* @return an empty `TreeSet`.
*/
def this()(implicit ord: Ordering[A]) = this(RB.Tree.empty)(ord)
override def sortedIterableFactory: SortedIterableFactory[TreeSet] = TreeSet
def iterator: collection.Iterator[A] = RB.keysIterator(tree)
def iteratorFrom(start: A): collection.Iterator[A] = RB.keysIterator(tree, Some(start))
override def stepper[S <: Stepper[_]](implicit shape: StepperShape[A, S]): S with EfficientSplit = {
import scala.collection.convert.impl._
type T = RB.Node[A, Null]
val s = shape.shape match {
case StepperShape.IntShape => IntBinaryTreeStepper.from[T] (size, tree.root, _.left, _.right, _.key.asInstanceOf[Int])
case StepperShape.LongShape => LongBinaryTreeStepper.from[T] (size, tree.root, _.left, _.right, _.key.asInstanceOf[Long])
case StepperShape.DoubleShape => DoubleBinaryTreeStepper.from[T](size, tree.root, _.left, _.right, _.key.asInstanceOf[Double])
case _ => shape.parUnbox(AnyBinaryTreeStepper.from[A, T](size, tree.root, _.left, _.right, _.key))
}
s.asInstanceOf[S with EfficientSplit]
}
def addOne(elem: A): this.type = {
RB.insert(tree, elem, null)
this
}
def subtractOne(elem: A): this.type = {
RB.delete(tree, elem)
this
}
def clear(): Unit = RB.clear(tree)
def contains(elem: A): Boolean = RB.contains(tree, elem)
def unconstrained: collection.Set[A] = this
def rangeImpl(from: Option[A], until: Option[A]): TreeSet[A] = new TreeSetProjection(from, until)
override protected[this] def className: String = "TreeSet"
override def size: Int = RB.size(tree)
override def knownSize: Int = size
override def isEmpty: Boolean = RB.isEmpty(tree)
override def head: A = RB.minKey(tree).get
override def last: A = RB.maxKey(tree).get
override def minAfter(key: A): Option[A] = RB.minKeyAfter(tree, key)
override def maxBefore(key: A): Option[A] = RB.maxKeyBefore(tree, key)
override def foreach[U](f: A => U): Unit = RB.foreachKey(tree, f)
/**
* A ranged projection of a [[TreeSet]]. Mutations on this set affect the original set and vice versa.
*
* Only keys between this projection's key range will ever appear as elements of this set, independently of whether
* the elements are added through the original set or through this view. That means that if one inserts an element in
* a view whose key is outside the view's bounds, calls to `contains` will _not_ consider the newly added element.
* Mutations are always reflected in the original set, though.
*
* @param from the lower bound (inclusive) of this projection wrapped in a `Some`, or `None` if there is no lower
* bound.
* @param until the upper bound (exclusive) of this projection wrapped in a `Some`, or `None` if there is no upper
* bound.
*/
private[this] final class TreeSetProjection(from: Option[A], until: Option[A]) extends TreeSet[A](tree) {
/**
* Given a possible new lower bound, chooses and returns the most constraining one (the maximum).
*/
private[this] def pickLowerBound(newFrom: Option[A]): Option[A] = (from, newFrom) match {
case (Some(fr), Some(newFr)) => Some(ordering.max(fr, newFr))
case (None, _) => newFrom
case _ => from
}
/**
* Given a possible new upper bound, chooses and returns the most constraining one (the minimum).
*/
private[this] def pickUpperBound(newUntil: Option[A]): Option[A] = (until, newUntil) match {
case (Some(unt), Some(newUnt)) => Some(ordering.min(unt, newUnt))
case (None, _) => newUntil
case _ => until
}
/**
* Returns true if the argument is inside the view bounds (between `from` and `until`).
*/
private[this] def isInsideViewBounds(key: A): Boolean = {
val afterFrom = from.isEmpty || ordering.compare(from.get, key) <= 0
val beforeUntil = until.isEmpty || ordering.compare(key, until.get) < 0
afterFrom && beforeUntil
}
override def rangeImpl(from: Option[A], until: Option[A]): TreeSet[A] =
new TreeSetProjection(pickLowerBound(from), pickUpperBound(until))
override def contains(key: A) = isInsideViewBounds(key) && RB.contains(tree, key)
override def iterator = RB.keysIterator(tree, from, until)
override def iteratorFrom(start: A) = RB.keysIterator(tree, pickLowerBound(Some(start)), until)
override def size = if (RB.size(tree) == 0) 0 else iterator.length
override def knownSize: Int = if (RB.size(tree) == 0) 0 else -1
override def isEmpty: Boolean = RB.size(tree) == 0 || !iterator.hasNext
override def head: A = headOption.get
override def headOption: Option[A] = {
val elem = if (from.isDefined) RB.minKeyAfter(tree, from.get) else RB.minKey(tree)
(elem, until) match {
case (Some(e), Some(unt)) if ordering.compare(e, unt) >= 0 => None
case _ => elem
}
}
override def last: A = lastOption.get
override def lastOption = {
val elem = if (until.isDefined) RB.maxKeyBefore(tree, until.get) else RB.maxKey(tree)
(elem, from) match {
case (Some(e), Some(fr)) if ordering.compare(e, fr) < 0 => None
case _ => elem
}
}
// Using the iterator should be efficient enough; if performance is deemed a problem later, a specialized
// `foreachKey(f, from, until)` method can be created in `RedBlackTree`. See
// https://github.com/scala/scala/pull/4608#discussion_r34307985 for a discussion about this.
override def foreach[U](f: A => U): Unit = iterator.foreach(f)
override def clone(): mutable.TreeSet[A] = super.clone().rangeImpl(from, until)
}
}
/**
* $factoryInfo
* @define Coll `mutable.TreeSet`
* @define coll mutable tree set
*/
@SerialVersionUID(3L)
object TreeSet extends SortedIterableFactory[TreeSet] {
def empty[A : Ordering]: TreeSet[A] = new TreeSet[A]()
def from[E](it: IterableOnce[E])(implicit ordering: Ordering[E]): TreeSet[E] =
it match {
case ts: TreeSet[E] if ordering == ts.ordering =>
new TreeSet[E](ts.tree.treeCopy())
case ss: scala.collection.SortedSet[E] if ordering == ss.ordering =>
new TreeSet[E](RB.fromOrderedKeys(ss.iterator, ss.size))
case r: Range if (ordering eq Ordering.Int) || (ordering eq Ordering.Int.reverse) =>
val it = if((ordering eq Ordering.Int) == (r.step > 0)) r.iterator else r.reverseIterator
new TreeSet[E](RB.fromOrderedKeys(it.asInstanceOf[Iterator[E]], r.size))
case _ =>
val t: RB.Tree[E, Null] = RB.Tree.empty
val i = it.iterator
while (i.hasNext) RB.insert(t, i.next(), null)
new TreeSet[E](t)
}
def newBuilder[A](implicit ordering: Ordering[A]): Builder[A, TreeSet[A]] = new ReusableBuilder[A, TreeSet[A]] {
private[this] var tree: RB.Tree[A, Null] = RB.Tree.empty
def addOne(elem: A): this.type = { RB.insert(tree, elem, null); this }
def result(): TreeSet[A] = new TreeSet[A](tree)
def clear(): Unit = { tree = RB.Tree.empty }
}
}