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/*
* 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
package mutable
import generic._
import scala.collection.mutable.{RedBlackTree => RB}
/**
* @define Coll `mutable.TreeSet`
* @define coll mutable tree set
* @factoryInfo
* Companion object of TreeSet providing factory related utilities.
*
* @author Lucien Pereira
*
*/
object TreeSet extends MutableSortedSetFactory[TreeSet] {
/**
* The empty set of this type
*/
def empty[A](implicit ordering: Ordering[A]) = new TreeSet[A]()
/** $sortedMapCanBuildFromInfo */
implicit def canBuildFrom[A](implicit ord: Ordering[A]): CanBuildFrom[Coll, A, TreeSet[A]] =
new SortedSetCanBuildFrom[A]
}
/**
* 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.
*
* @author Rui Gonçalves
* @since 2.10
*
* @define Coll mutable.TreeSet
* @define coll mutable tree set
*/
// Original API designed in part by Lucien Pereira
@SerialVersionUID(-3642111301929493640L)
sealed class TreeSet[A] private (tree: RB.Tree[A, Null])(implicit val ordering: Ordering[A])
extends AbstractSortedSet[A]
with SortedSet[A]
with SetLike[A, TreeSet[A]]
with SortedSetLike[A, TreeSet[A]]
with Serializable {
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 empty = TreeSet.empty
override protected[this] def newBuilder = TreeSet.newBuilder[A]
/**
* Creates a ranged projection of this set. Any mutations in the ranged projection affect will update 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.
*/
def rangeImpl(from: Option[A], until: Option[A]): TreeSet[A] = new TreeSetView(from, until)
def -=(key: A): this.type = { RB.delete(tree, key); this }
def +=(elem: A): this.type = { RB.insert(tree, elem, null); this }
def contains(elem: A) = RB.contains(tree, elem)
def iterator = RB.keysIterator(tree)
def keysIteratorFrom(start: A) = RB.keysIterator(tree, Some(start))
override def iteratorFrom(start: A) = RB.keysIterator(tree, Some(start))
override def size = RB.size(tree)
override def isEmpty = RB.isEmpty(tree)
override def head = RB.minKey(tree).get
override def headOption = RB.minKey(tree)
override def last = RB.maxKey(tree).get
override def lastOption = RB.maxKey(tree)
override def min[B >: A](implicit cmp: Ordering[B]): A =
if ((cmp == ordering) && nonEmpty) head else super.min(cmp)
override def max[B >: A](implicit cmp: Ordering[B]): A =
if ((cmp == ordering) && nonEmpty) last else super.max(cmp)
override def foreach[U](f: A => U): Unit = RB.foreachKey(tree, f)
override def clear(): Unit = RB.clear(tree)
override def stringPrefix = "TreeSet"
/**
* 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.
*/
@SerialVersionUID(7087824939194006086L)
private[this] final class TreeSetView(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 TreeSetView(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 keysIteratorFrom(start: A) = RB.keysIterator(tree, pickLowerBound(Some(start)), until)
override def iteratorFrom(start: A) = RB.keysIterator(tree, pickLowerBound(Some(start)), until)
override def size = iterator.length
override def isEmpty = !iterator.hasNext
override def head = headOption.get
override def headOption = {
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 = 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() = super.clone().rangeImpl(from, until)
}
}
