scala.collection.mutable.TreeMap.scala Maven / Gradle / Ivy
/*
* 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 scala.collection.generic._
import scala.collection.mutable.{RedBlackTree => RB}
/**
* $factoryInfo
*
* @define Coll mutable.TreeMap
* @define coll mutable tree map
*/
object TreeMap extends MutableSortedMapFactory[TreeMap] {
def empty[A, B](implicit ord: Ordering[A]) = new TreeMap[A, B]()(ord)
/** $sortedMapCanBuildFromInfo */
implicit def canBuildFrom[A, B](implicit ord: Ordering[A]): CanBuildFrom[Coll, (A, B), TreeMap[A, B]] =
new SortedMapCanBuildFrom[A, B]
}
/**
* A mutable sorted map 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 map.
* @tparam B the type of the values associated with the keys.
*
* @author Rui Gonçalves
* @since 2.12
*
* @define Coll mutable.TreeMap
* @define coll mutable tree map
*/
@SerialVersionUID(-2558985573956740112L)
sealed class TreeMap[A, B] private (tree: RB.Tree[A, B])(implicit val ordering: Ordering[A])
extends AbstractSortedMap[A, B]
with SortedMap[A, B]
with MapLike[A, B, TreeMap[A, B]]
with SortedMapLike[A, B, TreeMap[A, B]]
with Serializable {
/**
* Creates an empty `TreeMap`.
* @param ord the implicit ordering used to compare objects of type `A`.
* @return an empty `TreeMap`.
*/
def this()(implicit ord: Ordering[A]) = this(RB.Tree.empty)(ord)
override def empty = TreeMap.empty
override protected[this] def newBuilder = TreeMap.newBuilder[A, B]
/**
* Creates a ranged projection of this map. Any mutations in the ranged projection will update the original map and
* vice versa.
*
* Only entries with keys between this projection's key range will ever appear as elements of this map, independently
* of whether the entries are added through the original map or through this view. That means that if one inserts a
* key-value in a view whose key is outside the view's bounds, calls to `get` or `contains` will _not_ consider the
* newly added entry. Mutations are always reflected in the original map, 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]): TreeMap[A, B] = new TreeMapView(from, until)
def -=(key: A): this.type = { RB.delete(tree, key); this }
def +=(kv: (A, B)): this.type = { RB.insert(tree, kv._1, kv._2); this }
def get(key: A) = RB.get(tree, key)
def iterator = RB.iterator(tree)
def iteratorFrom(start: A) = RB.iterator(tree, Some(start))
def keysIteratorFrom(start: A) = RB.keysIterator(tree, Some(start))
def valuesIteratorFrom(start: A) = RB.valuesIterator(tree, Some(start))
override def size = RB.size(tree)
override def isEmpty = RB.isEmpty(tree)
override def contains(key: A) = RB.contains(tree, key)
override def head = RB.min(tree).get
override def headOption = RB.min(tree)
override def last = RB.max(tree).get
override def lastOption = RB.max(tree)
override def keysIterator = RB.keysIterator(tree)
override def valuesIterator = RB.valuesIterator(tree)
override def foreach[U](f: ((A, B)) => U): Unit = RB.foreach(tree, f)
override def transform(f: (A, B) => B) = { RB.transform(tree, f); this }
override def clear(): Unit = RB.clear(tree)
override def stringPrefix = "TreeMap"
/**
* A ranged projection of a [[TreeMap]]. Mutations on this map affect the original map and vice versa.
*
* Only entries with keys between this projection's key range will ever appear as elements of this map, independently
* of whether the entries are added through the original map or through this view. That means that if one inserts a
* key-value in a view whose key is outside the view's bounds, calls to `get` or `contains` will _not_ consider the
* newly added entry. Mutations are always reflected in the original map, 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(2219159283273389116L)
private[this] final class TreeMapView(from: Option[A], until: Option[A]) extends TreeMap[A, B](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]): TreeMap[A, B] =
new TreeMapView(pickLowerBound(from), pickUpperBound(until))
override def get(key: A) = if (isInsideViewBounds(key)) RB.get(tree, key) else None
override def iterator = RB.iterator(tree, from, until)
override def iteratorFrom(start: A) = RB.iterator(tree, pickLowerBound(Some(start)), until)
override def keysIteratorFrom(start: A) = RB.keysIterator(tree, pickLowerBound(Some(start)), until)
override def valuesIteratorFrom(start: A) = RB.valuesIterator(tree, pickLowerBound(Some(start)), until)
override def size = iterator.length
override def isEmpty = !iterator.hasNext
override def contains(key: A) = isInsideViewBounds(key) && RB.contains(tree, key)
override def head = headOption.get
override def headOption = {
val entry = if (from.isDefined) RB.minAfter(tree, from.get) else RB.min(tree)
(entry, until) match {
case (Some(e), Some(unt)) if ordering.compare(e._1, unt) >= 0 => None
case _ => entry
}
}
override def last = lastOption.get
override def lastOption = {
val entry = if (until.isDefined) RB.maxBefore(tree, until.get) else RB.max(tree)
(entry, from) match {
case (Some(e), Some(fr)) if ordering.compare(e._1, fr) < 0 => None
case _ => entry
}
}
// Using the iterator should be efficient enough; if performance is deemed a problem later, specialized
// `foreach(f, from, until)` and `transform(f, from, until)` methods 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, B)) => U): Unit = iterator.foreach(f)
override def transform(f: (A, B) => B) = {
iterator.foreach { case (key, value) => update(key, f(key, value)) }
this
}
override def valuesIterator: Iterator[B] = RB.valuesIterator(tree, from, until)
override def keysIterator: Iterator[A] = RB.keysIterator(tree, from, until)
override def clone() = super.clone().rangeImpl(from, until)
}
}
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