Many resources are needed to download a project. Please understand that we have to compensate our server costs. Thank you in advance. Project price only 1 $
You can buy this project and download/modify it how often you want.
/*
* 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 immutable
import java.lang.Integer.{bitCount, numberOfTrailingZeros}
import java.lang.System.arraycopy
import scala.collection.Hashing.improve
import scala.collection.Stepper.EfficientSplit
import scala.collection.generic.DefaultSerializable
import scala.collection.mutable.ReusableBuilder
import scala.runtime.Statics.releaseFence
import scala.util.hashing.MurmurHash3
/** This class implements immutable sets using a Compressed Hash-Array Mapped Prefix-tree.
* See paper https://michael.steindorfer.name/publications/oopsla15.pdf for more details.
*
* @tparam A the type of the elements contained in this hash set.
* @define Coll `immutable.HashSet`
* @define coll immutable champ hash set
*/
final class HashSet[A] private[immutable](private[immutable] val rootNode: BitmapIndexedSetNode[A])
extends AbstractSet[A]
with StrictOptimizedSetOps[A, HashSet, HashSet[A]]
with IterableFactoryDefaults[A, HashSet]
with DefaultSerializable {
def this() = this(SetNode.empty)
// This release fence is present because rootNode may have previously been mutated during construction.
releaseFence()
private[this] def newHashSetOrThis(newRootNode: BitmapIndexedSetNode[A]): HashSet[A] =
if (rootNode eq newRootNode) this else new HashSet(newRootNode)
override def iterableFactory: IterableFactory[HashSet] = HashSet
override def knownSize: Int = rootNode.size
override def size: Int = rootNode.size
override def isEmpty: Boolean = rootNode.size == 0
def iterator: Iterator[A] = {
if (isEmpty) Iterator.empty
else new SetIterator[A](rootNode)
}
protected[immutable] def reverseIterator: Iterator[A] = new SetReverseIterator[A](rootNode)
override def stepper[S <: Stepper[_]](implicit shape: StepperShape[A, S]): S with EfficientSplit = {
import convert.impl._
val s = shape.shape match {
case StepperShape.IntShape => IntChampStepper.from[ SetNode[A]](size, rootNode, (node, i) => node.getPayload(i).asInstanceOf[Int])
case StepperShape.LongShape => LongChampStepper.from[ SetNode[A]](size, rootNode, (node, i) => node.getPayload(i).asInstanceOf[Long])
case StepperShape.DoubleShape => DoubleChampStepper.from[SetNode[A]](size, rootNode, (node, i) => node.getPayload(i).asInstanceOf[Double])
case _ => shape.parUnbox(AnyChampStepper.from[A, SetNode[A]](size, rootNode, (node, i) => node.getPayload(i)))
}
s.asInstanceOf[S with EfficientSplit]
}
def contains(element: A): Boolean = {
val elementUnimprovedHash = element.##
val elementHash = improve(elementUnimprovedHash)
rootNode.contains(element, elementUnimprovedHash, elementHash, 0)
}
def incl(element: A): HashSet[A] = {
val elementUnimprovedHash = element.##
val elementHash = improve(elementUnimprovedHash)
val newRootNode = rootNode.updated(element, elementUnimprovedHash, elementHash, 0)
newHashSetOrThis(newRootNode)
}
def excl(element: A): HashSet[A] = {
val elementUnimprovedHash = element.##
val elementHash = improve(elementUnimprovedHash)
val newRootNode = rootNode.removed(element, elementUnimprovedHash, elementHash, 0)
newHashSetOrThis(newRootNode)
}
override def concat(that: IterableOnce[A]): HashSet[A] =
that match {
case hs: HashSet[A] =>
if (isEmpty) hs
else {
val newNode = rootNode.concat(hs.rootNode, 0)
if (newNode eq hs.rootNode) hs
else newHashSetOrThis(newNode)
}
case hs: collection.mutable.HashSet[A] =>
val iter = hs.nodeIterator
var current = rootNode
while (iter.hasNext) {
val next = iter.next()
val originalHash = hs.unimproveHash(next.hash)
val improved = improve(originalHash)
current = current.updated(next.key, originalHash, improved, 0)
if (current ne rootNode) {
var shallowlyMutableNodeMap = Node.bitposFrom(Node.maskFrom(improved, 0))
while (iter.hasNext) {
val next = iter.next()
val originalHash = hs.unimproveHash(next.hash)
val improved = improve(originalHash)
shallowlyMutableNodeMap = current.updateWithShallowMutations(next.key, originalHash, improved, 0, shallowlyMutableNodeMap)
}
return new HashSet(current)
}
}
this
case _ =>
val iter = that.iterator
var current = rootNode
while (iter.hasNext) {
val element = iter.next()
val originalHash = element.##
val improved = improve(originalHash)
current = current.updated(element, originalHash, improved, 0)
if (current ne rootNode) {
// Note: We could have started with shallowlyMutableNodeMap = 0, however this way, in the case that
// the first changed key ended up in a subnode beneath root, we mark that root right away as being
// shallowly mutable.
//
// since `element` has just been inserted, and certainly caused a new root node to be created, we can say with
// certainty that it either caused a new subnode to be created underneath `current`, in which case we should
// carry on mutating that subnode, or it ended up as a child data pair of the root, in which case, no harm is
// done by including its bit position in the shallowlyMutableNodeMap anyways.
var shallowlyMutableNodeMap = Node.bitposFrom(Node.maskFrom(improved, 0))
while (iter.hasNext) {
val element = iter.next()
val originalHash = element.##
val improved = improve(originalHash)
shallowlyMutableNodeMap = current.updateWithShallowMutations(element, originalHash, improved, 0, shallowlyMutableNodeMap)
}
return new HashSet(current)
}
}
this
}
override def tail: HashSet[A] = this - head
override def init: HashSet[A] = this - last
override def head: A = iterator.next()
override def last: A = reverseIterator.next()
override def foreach[U](f: A => U): Unit = rootNode.foreach(f)
/** Applies a function f to each element, and its corresponding **original** hash, in this Set */
@`inline` private[collection] def foreachWithHash(f: (A, Int) => Unit): Unit = rootNode.foreachWithHash(f)
/** Applies a function f to each element, and its corresponding **original** hash, in this Set
* Stops iterating the first time that f returns `false`.*/
@`inline` private[collection] def foreachWithHashWhile(f: (A, Int) => Boolean): Unit = rootNode.foreachWithHashWhile(f)
def subsetOf(that: Set[A]): Boolean = if (that.isEmpty) true else that match {
case set: HashSet[A] => rootNode.subsetOf(set.rootNode, 0)
case _ => super.subsetOf(that)
}
override def equals(that: Any): Boolean =
that match {
case set: HashSet[_] => (this eq set) || (this.rootNode == set.rootNode)
case _ => super.equals(that)
}
override protected[this] def className = "HashSet"
override def hashCode(): Int = {
val it = new SetHashIterator(rootNode)
val hash = MurmurHash3.unorderedHash(it, MurmurHash3.setSeed)
//assert(hash == super.hashCode())
hash
}
override def diff(that: collection.Set[A]): HashSet[A] = {
if (isEmpty) {
this
} else {
that match {
case hashSet: HashSet[A] =>
if (hashSet.isEmpty) this else {
val newRootNode = rootNode.diff(hashSet.rootNode, 0)
if (newRootNode.size == 0) HashSet.empty else newHashSetOrThis(rootNode.diff(hashSet.rootNode, 0))
}
case hashSet: collection.mutable.HashSet[A] =>
val iter = hashSet.nodeIterator
var curr = rootNode
while (iter.hasNext) {
val next = iter.next()
val originalHash = hashSet.unimproveHash(next.hash)
val improved = improve(originalHash)
curr = curr.removed(next.key, originalHash, improved, 0)
if (curr ne rootNode) {
if (curr.size == 0) {
return HashSet.empty
}
while (iter.hasNext) {
val next = iter.next()
val originalHash = hashSet.unimproveHash(next.hash)
val improved = improve(originalHash)
curr.removeWithShallowMutations(next.key, originalHash, improved)
if (curr.size == 0) {
return HashSet.empty
}
}
return new HashSet(curr)
}
}
this
case other =>
val thatKnownSize = other.knownSize
if (thatKnownSize == 0) {
this
} else if (thatKnownSize <= size) {
/* this branch intentionally includes the case of thatKnownSize == -1. We know that HashSets are quite fast at look-up, so
we're likely to be the faster of the two at that. */
removedAllWithShallowMutations(other)
} else {
// TODO: Develop more sophisticated heuristic for which branch to take
filterNot(other.contains)
}
}
}
}
/** Immutably removes all elements of `that` from this HashSet
*
* Mutation is used internally, but only on root SetNodes which this method itself creates.
*
* That is, this method is safe to call on published sets because it does not mutate `this`
*/
private[this] def removedAllWithShallowMutations(that: IterableOnce[A]): HashSet[A] = {
val iter = that.iterator
var curr = rootNode
while (iter.hasNext) {
val next = iter.next()
val originalHash = next.##
val improved = improve(originalHash)
curr = curr.removed(next, originalHash, improved, 0)
if (curr ne rootNode) {
if (curr.size == 0) {
return HashSet.empty
}
while (iter.hasNext) {
val next = iter.next()
val originalHash = next.##
val improved = improve(originalHash)
curr.removeWithShallowMutations(next, originalHash, improved)
if (curr.size == 0) {
return HashSet.empty
}
}
return new HashSet(curr)
}
}
this
}
override def removedAll(that: IterableOnce[A]): HashSet[A] = that match {
case set: scala.collection.Set[A] => diff(set)
case range: Range if range.length > size =>
filter {
case i: Int => !range.contains(i)
case _ => true
}
case _ =>
removedAllWithShallowMutations(that)
}
override def partition(p: A => Boolean): (HashSet[A], HashSet[A]) = {
// This method has been preemptively overridden in order to ensure that an optimizing implementation may be included
// in a minor release without breaking binary compatibility.
super.partition(p)
}
override def span(p: A => Boolean): (HashSet[A], HashSet[A]) = {
// This method has been preemptively overridden in order to ensure that an optimizing implementation may be included
// in a minor release without breaking binary compatibility.
super.span(p)
}
override protected[collection] def filterImpl(pred: A => Boolean, isFlipped: Boolean): HashSet[A] = {
val newRootNode = rootNode.filterImpl(pred, isFlipped)
if (newRootNode eq rootNode) this
else if (newRootNode.size == 0) HashSet.empty
else new HashSet(newRootNode)
}
override def intersect(that: collection.Set[A]): HashSet[A] = {
// This method has been preemptively overridden in order to ensure that an optimizing implementation may be included
// in a minor release without breaking binary compatibility.
super.intersect(that)
}
override def take(n: Int): HashSet[A] = {
// This method has been preemptively overridden in order to ensure that an optimizing implementation may be included
// in a minor release without breaking binary compatibility.
super.take(n)
}
override def takeRight(n: Int): HashSet[A] = {
// This method has been preemptively overridden in order to ensure that an optimizing implementation may be included
// in a minor release without breaking binary compatibility.
super.takeRight(n)
}
override def takeWhile(p: A => Boolean): HashSet[A] = {
// This method has been preemptively overridden in order to ensure that an optimizing implementation may be included
// in a minor release without breaking binary compatibility.
super.takeWhile(p)
}
override def drop(n: Int): HashSet[A] = {
// This method has been preemptively overridden in order to ensure that an optimizing implementation may be included
// in a minor release without breaking binary compatibility.
super.drop(n)
}
override def dropRight(n: Int): HashSet[A] = {
// This method has been preemptively overridden in order to ensure that an optimizing implementation may be included
// in a minor release without breaking binary compatibility.
super.dropRight(n)
}
override def dropWhile(p: A => Boolean): HashSet[A] = {
// This method has been preemptively overridden in order to ensure that an optimizing implementation may be included
// in a minor release without breaking binary compatibility.
super.dropWhile(p)
}
}
private[immutable] object SetNode {
private final val EmptySetNode = new BitmapIndexedSetNode(0, 0, Array.empty, Array.empty, 0, 0)
def empty[A]: BitmapIndexedSetNode[A] = EmptySetNode.asInstanceOf[BitmapIndexedSetNode[A]]
final val TupleLength = 1
}
private[immutable] sealed abstract class SetNode[A] extends Node[SetNode[A]] {
def contains(element: A, originalHash: Int, hash: Int, shift: Int): Boolean
def updated(element: A, originalHash: Int, hash: Int, shift: Int): SetNode[A]
def removed(element: A, originalHash: Int, hash: Int, shift: Int): SetNode[A]
def hasNodes: Boolean
def nodeArity: Int
def getNode(index: Int): SetNode[A]
def hasPayload: Boolean
def payloadArity: Int
def getPayload(index: Int): A
def size: Int
def foreach[U](f: A => U): Unit
def subsetOf(that: SetNode[A], shift: Int): Boolean
def copy(): SetNode[A]
def filterImpl(pred: A => Boolean, flipped: Boolean): SetNode[A]
def diff(that: SetNode[A], shift: Int): SetNode[A]
def concat(that: SetNode[A], shift: Int): SetNode[A]
def foreachWithHash(f: (A, Int) => Unit): Unit
def foreachWithHashWhile(f: (A, Int) => Boolean): Boolean
}
private final class BitmapIndexedSetNode[A](
var dataMap: Int,
var nodeMap: Int,
var content: Array[Any],
var originalHashes: Array[Int],
var size: Int,
var cachedJavaKeySetHashCode: Int) extends SetNode[A] {
import Node._
import SetNode._
/*
assert(checkInvariantContentIsWellTyped())
assert(checkInvariantSubNodesAreCompacted())
private final def checkInvariantSubNodesAreCompacted(): Boolean =
new SetIterator[A](this).size - payloadArity >= 2 * nodeArity
private final def checkInvariantContentIsWellTyped(): Boolean = {
val predicate1 = TupleLength * payloadArity + nodeArity == content.length
val predicate2 = Range(0, TupleLength * payloadArity)
.forall(i => content(i).isInstanceOf[SetNode[_]] == false)
val predicate3 = Range(TupleLength * payloadArity, content.length)
.forall(i => content(i).isInstanceOf[SetNode[_]] == true)
predicate1 && predicate2 && predicate3
}
*/
def getPayload(index: Int): A = content(index).asInstanceOf[A]
override def getHash(index: Int): Int = originalHashes(index)
def getNode(index: Int): SetNode[A] = content(content.length - 1 - index).asInstanceOf[SetNode[A]]
def contains(element: A, originalHash: Int, elementHash: Int, shift: Int): Boolean = {
val mask = maskFrom(elementHash, shift)
val bitpos = bitposFrom(mask)
if ((dataMap & bitpos) != 0) {
val index = indexFrom(dataMap, mask, bitpos)
return originalHashes(index) == originalHash && element == this.getPayload(index)
}
if ((nodeMap & bitpos) != 0) {
val index = indexFrom(nodeMap, mask, bitpos)
return this.getNode(index).contains(element, originalHash, elementHash, shift + BitPartitionSize)
}
false
}
def updated(element: A, originalHash: Int, elementHash: Int, shift: Int): BitmapIndexedSetNode[A] = {
val mask = maskFrom(elementHash, shift)
val bitpos = bitposFrom(mask)
if ((dataMap & bitpos) != 0) {
val index = indexFrom(dataMap, mask, bitpos)
val element0 = this.getPayload(index)
if (element0.asInstanceOf[AnyRef] eq element.asInstanceOf[AnyRef]) {
return this
} else {
val element0UnimprovedHash = getHash(index)
val element0Hash = improve(element0UnimprovedHash)
if (originalHash == element0UnimprovedHash && element0 == element) {
return this
} else {
val subNodeNew = mergeTwoKeyValPairs(element0, element0UnimprovedHash, element0Hash, element, originalHash, elementHash, shift + BitPartitionSize)
return copyAndMigrateFromInlineToNode(bitpos, element0Hash, subNodeNew)
}
}
}
if ((nodeMap & bitpos) != 0) {
val index = indexFrom(nodeMap, mask, bitpos)
val subNode = this.getNode(index)
val subNodeNew = subNode.updated(element, originalHash, elementHash, shift + BitPartitionSize)
if (subNode eq subNodeNew) {
return this
} else {
return copyAndSetNode(bitpos, subNode, subNodeNew)
}
}
copyAndInsertValue(bitpos, element, originalHash, elementHash)
}
/** A variant of `updated` which performs shallow mutations on the root (`this`), and if possible, on immediately
* descendant child nodes (only one level beneath `this`)
*
* The caller should pass a bitmap of child nodes of this node, which this method may mutate.
* If this method may mutate a child node, then if the updated value is located in that child node, it will
* be shallowly mutated (its children will not be mutated).
*
* If instead this method may not mutate the child node in which the to-be-updated value is located, then
* that child will be updated immutably, but the result will be mutably re-inserted as a child of this node.
*
* @param key the key to update
* @param originalHash key.##
* @param keyHash the improved hash
* @param shallowlyMutableNodeMap bitmap of child nodes of this node, which can be shallowly mutated
* during the call to this method
*
* @return Int which is the bitwise OR of shallowlyMutableNodeMap and any freshly created nodes, which will be
* available for mutations in subsequent calls.
*/
def updateWithShallowMutations(element: A, originalHash: Int, elementHash: Int, shift: Int, shallowlyMutableNodeMap: Int): Int = {
val mask = maskFrom(elementHash, shift)
val bitpos = bitposFrom(mask)
if ((dataMap & bitpos) != 0) {
val index = indexFrom(dataMap, mask, bitpos)
val element0 = getPayload(index)
val element0UnimprovedHash = getHash(index)
if (element0UnimprovedHash == originalHash && element0 == element) {
shallowlyMutableNodeMap
} else {
val element0Hash = improve(element0UnimprovedHash)
val subNodeNew = mergeTwoKeyValPairs(element0, element0UnimprovedHash, element0Hash, element, originalHash, elementHash, shift + BitPartitionSize)
migrateFromInlineToNodeInPlace(bitpos, element0Hash, subNodeNew)
shallowlyMutableNodeMap | bitpos
}
} else if ((nodeMap & bitpos) != 0) {
val index = indexFrom(nodeMap, mask, bitpos)
val subNode = this.getNode(index)
val subNodeSize = subNode.size
val subNodeCachedJavaKeySetHashCode = subNode.cachedJavaKeySetHashCode
var returnNodeMap = shallowlyMutableNodeMap
val subNodeNew: SetNode[A] = subNode match {
case subNodeBm: BitmapIndexedSetNode[A] if (bitpos & shallowlyMutableNodeMap) != 0 =>
subNodeBm.updateWithShallowMutations(element, originalHash, elementHash, shift + BitPartitionSize, 0)
subNodeBm
case _ =>
val subNodeNew = subNode.updated(element, originalHash, elementHash, shift + BitPartitionSize)
if (subNodeNew ne subNode) {
returnNodeMap |= bitpos
}
subNodeNew
}
this.content(this.content.length - 1 - this.nodeIndex(bitpos)) = subNodeNew
this.size = this.size - subNodeSize + subNodeNew.size
this.cachedJavaKeySetHashCode = this.cachedJavaKeySetHashCode - subNodeCachedJavaKeySetHashCode + subNodeNew.cachedJavaKeySetHashCode
returnNodeMap
} else {
val dataIx = dataIndex(bitpos)
val idx = dataIx
val src = this.content
val dst = new Array[Any](src.length + TupleLength)
// copy 'src' and insert 2 element(s) at position 'idx'
arraycopy(src, 0, dst, 0, idx)
dst(idx) = element
arraycopy(src, idx, dst, idx + TupleLength, src.length - idx)
val dstHashes = insertElement(originalHashes, dataIx, originalHash)
this.dataMap |= bitpos
this.content = dst
this.originalHashes = dstHashes
this.size += 1
this.cachedJavaKeySetHashCode += elementHash
shallowlyMutableNodeMap
}
}
def removed(element: A, originalHash: Int, elementHash: Int, shift: Int): BitmapIndexedSetNode[A] = {
val mask = maskFrom(elementHash, shift)
val bitpos = bitposFrom(mask)
if ((dataMap & bitpos) != 0) {
val index = indexFrom(dataMap, mask, bitpos)
val element0 = this.getPayload(index)
if (element0 == element) {
if (this.payloadArity == 2 && this.nodeArity == 0) {
/*
* Create new node with remaining pair. The new node will a) either become the new root
* returned, or b) unwrapped and inlined during returning.
*/
val newDataMap = if (shift == 0) (dataMap ^ bitpos) else bitposFrom(maskFrom(elementHash, 0))
if (index == 0)
return new BitmapIndexedSetNode[A](newDataMap, 0, Array(getPayload(1)), Array(originalHashes(1)), size - 1, improve(originalHashes(1)))
else
return new BitmapIndexedSetNode[A](newDataMap, 0, Array(getPayload(0)), Array(originalHashes(0)), size - 1, improve(originalHashes(0)))
}
else return copyAndRemoveValue(bitpos, elementHash)
} else return this
}
if ((nodeMap & bitpos) != 0) {
val index = indexFrom(nodeMap, mask, bitpos)
val subNode = this.getNode(index)
val subNodeNew = subNode.removed(element, originalHash, elementHash, shift + BitPartitionSize)
if (subNodeNew eq subNode) return this
// cache just in case subNodeNew is a hashCollision node, in which in which case a little arithmetic is avoided
// in Vector#length
val subNodeNewSize = subNodeNew.size
if (subNodeNewSize == 1) {
if (this.size == subNode.size) {
// subNode is the only child (no other data or node children of `this` exist)
// escalate (singleton or empty) result
return subNodeNew.asInstanceOf[BitmapIndexedSetNode[A]]
} else {
// inline value (move to front)
return copyAndMigrateFromNodeToInline(bitpos, elementHash, subNode, subNodeNew)
}
} else if (subNodeNewSize > 1) {
// modify current node (set replacement node)
return copyAndSetNode(bitpos, subNode, subNodeNew)
}
}
this
}
/** Variant of `removed` which will perform mutation on only the top-level node (`this`), rather than return a new
* node
*
* Should only be called on root nodes, because shift is assumed to be 0
*
* @param element the element to remove
* @param originalHash the original hash of `element`
* @param elementHash the improved hash of `element`
*/
def removeWithShallowMutations(element: A, originalHash: Int, elementHash: Int): this.type = {
val mask = maskFrom(elementHash, 0)
val bitpos = bitposFrom(mask)
if ((dataMap & bitpos) != 0) {
val index = indexFrom(dataMap, mask, bitpos)
val element0 = this.getPayload(index)
if (element0 == element) {
if (this.payloadArity == 2 && this.nodeArity == 0) {
val newDataMap = dataMap ^ bitpos
if (index == 0) {
val newContent = Array[Any](getPayload(1))
val newOriginalHashes = Array(originalHashes(1))
val newCachedJavaKeySetHashCode = improve(getHash(1))
this.content = newContent
this.originalHashes = newOriginalHashes
this.cachedJavaKeySetHashCode = newCachedJavaKeySetHashCode
} else {
val newContent = Array[Any](getPayload(0))
val newOriginalHashes = Array(originalHashes(0))
val newCachedJavaKeySetHashCode = improve(getHash(0))
this.content = newContent
this.originalHashes = newOriginalHashes
this.cachedJavaKeySetHashCode = newCachedJavaKeySetHashCode
}
this.dataMap = newDataMap
this.nodeMap = 0
this.size = 1
this
}
else {
val dataIx = dataIndex(bitpos)
val idx = TupleLength * dataIx
val src = this.content
val dst = new Array[Any](src.length - TupleLength)
arraycopy(src, 0, dst, 0, idx)
arraycopy(src, idx + TupleLength, dst, idx, src.length - idx - TupleLength)
val dstHashes = removeElement(originalHashes, dataIx)
this.dataMap = this.dataMap ^ bitpos
this.content = dst
this.originalHashes = dstHashes
this.size -= 1
this.cachedJavaKeySetHashCode -= elementHash
this
}
} else this
} else if ((nodeMap & bitpos) != 0) {
val index = indexFrom(nodeMap, mask, bitpos)
val subNode = this.getNode(index)
val subNodeNew = subNode.removed(element, originalHash, elementHash, BitPartitionSize).asInstanceOf[BitmapIndexedSetNode[A]]
if (subNodeNew eq subNode) return this
if (subNodeNew.size == 1) {
if (this.payloadArity == 0 && this.nodeArity == 1) {
this.dataMap = subNodeNew.dataMap
this.nodeMap = subNodeNew.nodeMap
this.content = subNodeNew.content
this.originalHashes = subNodeNew.originalHashes
this.size = subNodeNew.size
this.cachedJavaKeySetHashCode = subNodeNew.cachedJavaKeySetHashCode
this
} else {
migrateFromNodeToInlineInPlace(bitpos, originalHash, elementHash, subNode, subNodeNew)
this
}
} else {
// size must be > 1
this.content(this.content.length - 1 - this.nodeIndex(bitpos)) = subNodeNew
this.size -= 1
this.cachedJavaKeySetHashCode = this.cachedJavaKeySetHashCode - subNode.cachedJavaKeySetHashCode + subNodeNew.cachedJavaKeySetHashCode
this
}
} else this
}
def mergeTwoKeyValPairs(key0: A, originalKeyHash0: Int, keyHash0: Int, key1: A, originalKeyHash1: Int, keyHash1: Int, shift: Int): SetNode[A] = {
// assert(key0 != key1)
if (shift >= HashCodeLength) {
new HashCollisionSetNode[A](originalKeyHash0, keyHash0, Vector(key0, key1))
} else {
val mask0 = maskFrom(keyHash0, shift)
val mask1 = maskFrom(keyHash1, shift)
if (mask0 != mask1) {
// unique prefixes, payload fits on same level
val dataMap = bitposFrom(mask0) | bitposFrom(mask1)
val newCachedHashCode = keyHash0 + keyHash1
if (mask0 < mask1) {
new BitmapIndexedSetNode[A](dataMap, 0, Array(key0, key1), Array(originalKeyHash0, originalKeyHash1), 2, newCachedHashCode)
} else {
new BitmapIndexedSetNode[A](dataMap, 0, Array(key1, key0), Array(originalKeyHash1, originalKeyHash0), 2, newCachedHashCode)
}
} else {
// identical prefixes, payload must be disambiguated deeper in the trie
val nodeMap = bitposFrom(mask0)
val node = mergeTwoKeyValPairs(key0, originalKeyHash0, keyHash0, key1, originalKeyHash1, keyHash1, shift + BitPartitionSize)
new BitmapIndexedSetNode[A](0, nodeMap, Array(node), Array.emptyIntArray, node.size, node.cachedJavaKeySetHashCode)
}
}
}
def hasPayload: Boolean = dataMap != 0
def payloadArity: Int = bitCount(dataMap)
def hasNodes: Boolean = nodeMap != 0
def nodeArity: Int = bitCount(nodeMap)
def dataIndex(bitpos: Int) = bitCount(dataMap & (bitpos - 1))
def nodeIndex(bitpos: Int) = bitCount(nodeMap & (bitpos - 1))
def copyAndSetNode(bitpos: Int, oldNode: SetNode[A], newNode: SetNode[A]) = {
val idx = this.content.length - 1 - this.nodeIndex(bitpos)
val src = this.content
val dst = new Array[Any](src.length)
// copy 'src' and set 1 element(s) at position 'idx'
arraycopy(src, 0, dst, 0, src.length)
dst(idx) = newNode
new BitmapIndexedSetNode[A](
dataMap = dataMap,
nodeMap = nodeMap,
content = dst,
originalHashes = originalHashes,
size = size - oldNode.size + newNode.size,
cachedJavaKeySetHashCode = cachedJavaKeySetHashCode - oldNode.cachedJavaKeySetHashCode + newNode.cachedJavaKeySetHashCode
)
}
def copyAndInsertValue(bitpos: Int, key: A, originalHash: Int, elementHash: Int) = {
val dataIx = dataIndex(bitpos)
val idx = TupleLength * dataIx
val src = this.content
val dst = new Array[Any](src.length + 1)
// copy 'src' and insert 1 element(s) at position 'idx'
arraycopy(src, 0, dst, 0, idx)
dst(idx) = key
arraycopy(src, idx, dst, idx + 1, src.length - idx)
val dstHashes = insertElement(originalHashes, dataIx, originalHash)
new BitmapIndexedSetNode[A](dataMap | bitpos, nodeMap, dst, dstHashes, size + 1, cachedJavaKeySetHashCode + elementHash)
}
def copyAndSetValue(bitpos: Int, key: A, originalHash: Int, elementHash: Int) = {
val dataIx = dataIndex(bitpos)
val idx = TupleLength * dataIx
val src = this.content
val dst = new Array[Any](src.length)
// copy 'src' and set 1 element(s) at position 'idx'
arraycopy(src, 0, dst, 0, src.length)
dst(idx) = key
new BitmapIndexedSetNode[A](dataMap | bitpos, nodeMap, dst, originalHashes, size, cachedJavaKeySetHashCode)
}
def copyAndRemoveValue(bitpos: Int, elementHash: Int) = {
val dataIx = dataIndex(bitpos)
val idx = TupleLength * dataIx
val src = this.content
val dst = new Array[Any](src.length - 1)
// copy 'src' and remove 1 element(s) at position 'idx'
arraycopy(src, 0, dst, 0, idx)
arraycopy(src, idx + 1, dst, idx, src.length - idx - 1)
val dstHashes = removeElement(originalHashes, dataIx)
new BitmapIndexedSetNode[A](dataMap ^ bitpos, nodeMap, dst, dstHashes, size - 1, cachedJavaKeySetHashCode - elementHash)
}
def copyAndMigrateFromInlineToNode(bitpos: Int, elementHash: Int, node: SetNode[A]) = {
val dataIx = dataIndex(bitpos)
val idxOld = TupleLength * dataIx
val idxNew = this.content.length - TupleLength - nodeIndex(bitpos)
val src = this.content
val dst = new Array[Any](src.length - 1 + 1)
// copy 'src' and remove 1 element(s) at position 'idxOld' and
// insert 1 element(s) at position 'idxNew'
// assert(idxOld <= idxNew)
arraycopy(src, 0, dst, 0, idxOld)
arraycopy(src, idxOld + 1, dst, idxOld, idxNew - idxOld)
dst(idxNew) = node
arraycopy(src, idxNew + 1, dst, idxNew + 1, src.length - idxNew - 1)
val dstHashes = removeElement(originalHashes, dataIx)
new BitmapIndexedSetNode[A](
dataMap = dataMap ^ bitpos,
nodeMap = nodeMap | bitpos,
content = dst, originalHashes = dstHashes,
size = size - 1 + node.size,
cachedJavaKeySetHashCode = cachedJavaKeySetHashCode - elementHash + node.cachedJavaKeySetHashCode
)
}
/** Variant of `copyAndMigrateFromInlineToNode` which mutates `this` rather than returning a new node.
*
* Note: This method will mutate `this`, and will mutate `this.content`
*
* Mutation of `this.content` will occur as an optimization not possible in maps. Since TupleLength == 1 for sets,
* content array size does not change during inline <-> node migrations. Therefor, since we are updating in-place,
* we reuse this.content by shifting data/nodes around, rather than allocating a new array.
*
* @param bitpos the bit position of the data to migrate to node
* @param keyHash the improved hash of the element currently at `bitpos`
* @param node the node to place at `bitpos`
*/
def migrateFromInlineToNodeInPlace(bitpos: Int, keyHash: Int, node: SetNode[A]): this.type = {
val dataIx = dataIndex(bitpos)
val idxOld = TupleLength * dataIx
val idxNew = this.content.length - TupleLength - nodeIndex(bitpos)
arraycopy(content, idxOld + TupleLength, content, idxOld, idxNew - idxOld)
content(idxNew) = node
this.dataMap = this.dataMap ^ bitpos
this.nodeMap = this.nodeMap | bitpos
this.originalHashes = removeElement(originalHashes, dataIx)
this.size = this.size - 1 + node.size
this.cachedJavaKeySetHashCode = this.cachedJavaKeySetHashCode - keyHash + node.cachedJavaKeySetHashCode
this
}
def copyAndMigrateFromNodeToInline(bitpos: Int, elementHash: Int, oldNode: SetNode[A], node: SetNode[A]) = {
val idxOld = this.content.length - 1 - nodeIndex(bitpos)
val dataIxNew = dataIndex(bitpos)
val idxNew = TupleLength * dataIxNew
val src = this.content
val dst = new Array[Any](src.length - 1 + 1)
// copy 'src' and remove 1 element(s) at position 'idxOld' and
// insert 1 element(s) at position 'idxNew'
// assert(idxOld >= idxNew)
arraycopy(src, 0, dst, 0, idxNew)
dst(idxNew) = node.getPayload(0)
arraycopy(src, idxNew, dst, idxNew + 1, idxOld - idxNew)
arraycopy(src, idxOld + 1, dst, idxOld + 1, src.length - idxOld - 1)
val hash = node.getHash(0)
val dstHashes = insertElement(originalHashes, dataIxNew, hash)
new BitmapIndexedSetNode[A](
dataMap = dataMap | bitpos,
nodeMap = nodeMap ^ bitpos,
content = dst,
originalHashes = dstHashes,
size = size - oldNode.size + 1,
cachedJavaKeySetHashCode = cachedJavaKeySetHashCode - oldNode.cachedJavaKeySetHashCode + node.cachedJavaKeySetHashCode
)
}
/** Variant of `copyAndMigrateFromNodeToInline` which mutates `this` rather than returning a new node.
*
* Note: This method will mutate `this`, and will mutate `this.content`
*
* Mutation of `this.content` will occur as an optimization not possible in maps. Since TupleLength == 1 for sets,
* content array size does not change during inline <-> node migrations. Therefor, since we are updating in-place,
* we reuse this.content by shifting data/nodes around, rather than allocating a new array.
*
* @param bitpos the bit position of the node to migrate inline
* @param oldNode the node currently stored at position `bitpos`
* @param node the node containing the single element to migrate inline
*/
def migrateFromNodeToInlineInPlace(bitpos: Int, originalHash: Int, elementHash: Int, oldNode: SetNode[A], node: SetNode[A]): Unit = {
val idxOld = this.content.length - 1 - nodeIndex(bitpos)
val dataIxNew = dataIndex(bitpos)
val element = node.getPayload(0)
arraycopy(content, dataIxNew, content, dataIxNew + 1, idxOld - dataIxNew)
content(dataIxNew) = element
val hash = node.getHash(0)
val dstHashes = insertElement(originalHashes, dataIxNew, hash)
this.dataMap = this.dataMap | bitpos
this.nodeMap = this.nodeMap ^ bitpos
this.originalHashes = dstHashes
this.size = this.size - oldNode.size + 1
this.cachedJavaKeySetHashCode = this.cachedJavaKeySetHashCode - oldNode.cachedJavaKeySetHashCode + node.cachedJavaKeySetHashCode
}
def foreach[U](f: A => U): Unit = {
val thisPayloadArity = payloadArity
var i = 0
while (i < thisPayloadArity) {
f(getPayload(i))
i += 1
}
val thisNodeArity = nodeArity
var j = 0
while (j < thisNodeArity) {
getNode(j).foreach(f)
j += 1
}
}
def subsetOf(that: SetNode[A], shift: Int): Boolean = if (this eq that) true else that match {
case _: HashCollisionSetNode[A] => false
case node: BitmapIndexedSetNode[A] =>
val thisBitmap = this.dataMap | this.nodeMap
val nodeBitmap = node.dataMap | node.nodeMap
if ((thisBitmap | nodeBitmap) != nodeBitmap)
return false
var bitmap = thisBitmap & nodeBitmap
var bitsToSkip = numberOfTrailingZeros(bitmap)
var isValidSubset = true
while (isValidSubset && bitsToSkip < HashCodeLength) {
val bitpos = bitposFrom(bitsToSkip)
isValidSubset =
if ((this.dataMap & bitpos) != 0) {
if ((node.dataMap & bitpos) != 0) {
// Data x Data
val payload0 = this.getPayload(indexFrom(this.dataMap, bitpos))
val payload1 = node.getPayload(indexFrom(node.dataMap, bitpos))
payload0 == payload1
} else {
// Data x Node
val thisDataIndex = indexFrom(this.dataMap, bitpos)
val payload = this.getPayload(thisDataIndex)
val subNode = that.getNode(indexFrom(node.nodeMap, bitpos))
val elementUnimprovedHash = getHash(thisDataIndex)
val elementHash = improve(elementUnimprovedHash)
subNode.contains(payload, elementUnimprovedHash, elementHash, shift + BitPartitionSize)
}
} else {
// Node x Node
val subNode0 = this.getNode(indexFrom(this.nodeMap, bitpos))
val subNode1 = node.getNode(indexFrom(node.nodeMap, bitpos))
subNode0.subsetOf(subNode1, shift + BitPartitionSize)
}
val newBitmap = bitmap ^ bitpos
bitmap = newBitmap
bitsToSkip = numberOfTrailingZeros(newBitmap)
}
isValidSubset
}
override def filterImpl(pred: A => Boolean, flipped: Boolean): BitmapIndexedSetNode[A] = {
if (size == 0) this
else if (size == 1) {
if (pred(getPayload(0)) != flipped) this else SetNode.empty
} else if (nodeMap == 0) {
// Performance optimization for nodes of depth 1:
//
// this node has no "node" children, all children are inlined data elems, therefor logic is significantly simpler
// approach:
// * traverse the content array, accumulating in `newDataMap: Int` any bit positions of keys which pass the filter
// * (bitCount(newDataMap) * TupleLength) tells us the new content array and originalHashes array size, so now perform allocations
// * traverse the content array once more, placing each passing element (according to `newDatamap`) in the new content and originalHashes arrays
//
// note:
// * this optimization significantly improves performance of not only small trees, but also larger trees, since
// even non-root nodes are affected by this improvement, and large trees will consist of many nodes as
// descendants
//
val minimumIndex: Int = Integer.numberOfTrailingZeros(dataMap)
val maximumIndex: Int = Node.BranchingFactor - Integer.numberOfLeadingZeros(dataMap)
var newDataMap = 0
var newCachedHashCode = 0
var dataIndex = 0
var i = minimumIndex
while(i < maximumIndex) {
val bitpos = bitposFrom(i)
if ((bitpos & dataMap) != 0) {
val payload = getPayload(dataIndex)
val passed = pred(payload) != flipped
if (passed) {
newDataMap |= bitpos
newCachedHashCode += improve(getHash(dataIndex))
}
dataIndex += 1
}
i += 1
}
if (newDataMap == 0) {
SetNode.empty
} else if (newDataMap == dataMap) {
this
} else {
val newSize = Integer.bitCount(newDataMap)
val newContent = new Array[Any](newSize)
val newOriginalHashCodes = new Array[Int](newSize)
val newMaximumIndex: Int = Node.BranchingFactor - Integer.numberOfLeadingZeros(newDataMap)
var j = Integer.numberOfTrailingZeros(newDataMap)
var newDataIndex = 0
while (j < newMaximumIndex) {
val bitpos = bitposFrom(j)
if ((bitpos & newDataMap) != 0) {
val oldIndex = indexFrom(dataMap, bitpos)
newContent(newDataIndex) = content(oldIndex)
newOriginalHashCodes(newDataIndex) = originalHashes(oldIndex)
newDataIndex += 1
}
j += 1
}
new BitmapIndexedSetNode(newDataMap, 0, newContent, newOriginalHashCodes, newSize, newCachedHashCode)
}
} else {
val allMap = dataMap | nodeMap
val minimumIndex: Int = Integer.numberOfTrailingZeros(allMap)
val maximumIndex: Int = Node.BranchingFactor - Integer.numberOfLeadingZeros(allMap)
var oldDataPassThrough = 0
// bitmap of nodes which, when filtered, returned a single-element node. These must be migrated to data
var nodeMigrateToDataTargetMap = 0
// TODO: When filtering results in a single-elem node, simply `(A, originalHash, improvedHash)` could be returned,
// rather than a singleton node (to avoid pointlessly allocating arrays, nodes, which would just be inlined in
// the parent anyways). This would probably involve changing the return type of filterImpl to `AnyRef` which may
// return at runtime a SetNode[A], or a tuple of (A, Int, Int)
// the queue of single-element, post-filter nodes
var nodesToMigrateToData: mutable.Queue[SetNode[A]] = null
// bitmap of all nodes which, when filtered, returned themselves. They are passed forward to the returned node
var nodesToPassThroughMap = 0
// bitmap of any nodes which, after being filtered, returned a node that is not empty, but also not `eq` itself
// These are stored for later inclusion into the final `content` array
// not named `newNodesMap` (plural) to avoid confusion with `newNodeMap` (singular)
var mapOfNewNodes = 0
// each bit in `mapOfNewNodes` corresponds to one element in this queue
var newNodes: mutable.Queue[SetNode[A]] = null
var newDataMap = 0
var newNodeMap = 0
var newSize = 0
var newCachedHashCode = 0
var dataIndex = 0
var nodeIndex = 0
var i = minimumIndex
while (i < maximumIndex) {
val bitpos = bitposFrom(i)
if ((bitpos & dataMap) != 0) {
val payload = getPayload(dataIndex)
val passed = pred(payload) != flipped
if (passed) {
newDataMap |= bitpos
oldDataPassThrough |= bitpos
newSize += 1
newCachedHashCode += improve(getHash(dataIndex))
}
dataIndex += 1
} else if ((bitpos & nodeMap) != 0) {
val oldSubNode = getNode(nodeIndex)
val newSubNode = oldSubNode.filterImpl(pred, flipped)
newSize += newSubNode.size
newCachedHashCode += newSubNode.cachedJavaKeySetHashCode
// if (newSubNode.size == 0) do nothing (drop it)
if (newSubNode.size > 1) {
newNodeMap |= bitpos
if (oldSubNode eq newSubNode) {
nodesToPassThroughMap |= bitpos
} else {
mapOfNewNodes |= bitpos
if (newNodes eq null) {
newNodes = mutable.Queue.empty
}
newNodes += newSubNode
}
} else if (newSubNode.size == 1) {
newDataMap |= bitpos
nodeMigrateToDataTargetMap |= bitpos
if (nodesToMigrateToData eq null) {
nodesToMigrateToData = mutable.Queue.empty
}
nodesToMigrateToData += newSubNode
}
nodeIndex += 1
}
i += 1
}
this.newNodeFrom(
newSize = newSize,
newDataMap = newDataMap,
newNodeMap = newNodeMap,
minimumIndex = minimumIndex,
oldDataPassThrough = oldDataPassThrough,
nodesToPassThroughMap = nodesToPassThroughMap,
nodeMigrateToDataTargetMap = nodeMigrateToDataTargetMap,
nodesToMigrateToData = nodesToMigrateToData,
mapOfNewNodes = mapOfNewNodes,
newNodes = newNodes,
newCachedHashCode = newCachedHashCode
)
}
}
override def diff(that: SetNode[A], shift: Int): BitmapIndexedSetNode[A] = that match {
case bm: BitmapIndexedSetNode[A] =>
if (size == 0) this
else if (size == 1) {
val h = getHash(0)
if (that.contains(getPayload(0), h, improve(h), shift)) SetNode.empty else this
} else {
val allMap = dataMap | nodeMap
val minimumIndex: Int = Integer.numberOfTrailingZeros(allMap)
val maximumIndex: Int = Node.BranchingFactor - Integer.numberOfLeadingZeros(allMap)
var oldDataPassThrough = 0
// bitmap of nodes which, when filtered, returned a single-element node. These must be migrated to data
var nodeMigrateToDataTargetMap = 0
// the queue of single-element, post-filter nodes
var nodesToMigrateToData: mutable.Queue[SetNode[A]] = null
// bitmap of all nodes which, when filtered, returned themselves. They are passed forward to the returned node
var nodesToPassThroughMap = 0
// bitmap of any nodes which, after being filtered, returned a node that is not empty, but also not `eq` itself
// These are stored for later inclusion into the final `content` array
// not named `newNodesMap` (plural) to avoid confusion with `newNodeMap` (singular)
var mapOfNewNodes = 0
// each bit in `mapOfNewNodes` corresponds to one element in this queue
var newNodes: mutable.Queue[SetNode[A]] = null
var newDataMap = 0
var newNodeMap = 0
var newSize = 0
var newCachedHashCode = 0
var dataIndex = 0
var nodeIndex = 0
var i = minimumIndex
while (i < maximumIndex) {
val bitpos = bitposFrom(i)
if ((bitpos & dataMap) != 0) {
val payload = getPayload(dataIndex)
val originalHash = getHash(dataIndex)
val hash = improve(originalHash)
if (!bm.contains(payload, originalHash, hash, shift)) {
newDataMap |= bitpos
oldDataPassThrough |= bitpos
newSize += 1
newCachedHashCode += hash
}
dataIndex += 1
} else if ((bitpos & nodeMap) != 0) {
val oldSubNode = getNode(nodeIndex)
val newSubNode: SetNode[A] =
if ((bitpos & bm.dataMap) != 0) {
val thatDataIndex = indexFrom(bm.dataMap, bitpos)
val thatPayload = bm.getPayload(thatDataIndex)
val thatOriginalHash = bm.getHash(thatDataIndex)
val thatHash = improve(thatOriginalHash)
oldSubNode.removed(thatPayload, thatOriginalHash, thatHash, shift + BitPartitionSize)
} else if ((bitpos & bm.nodeMap) != 0) {
oldSubNode.diff(bm.getNode(indexFrom(bm.nodeMap, bitpos)), shift + BitPartitionSize)
} else {
oldSubNode
}
newSize += newSubNode.size
newCachedHashCode += newSubNode.cachedJavaKeySetHashCode
// if (newSubNode.size == 0) do nothing (drop it)
if (newSubNode.size > 1) {
newNodeMap |= bitpos
if (oldSubNode eq newSubNode) {
nodesToPassThroughMap |= bitpos
} else {
mapOfNewNodes |= bitpos
if (newNodes eq null) {
newNodes = mutable.Queue.empty
}
newNodes += newSubNode
}
} else if (newSubNode.size == 1) {
newDataMap |= bitpos
nodeMigrateToDataTargetMap |= bitpos
if (nodesToMigrateToData eq null) {
nodesToMigrateToData = mutable.Queue.empty
}
nodesToMigrateToData += newSubNode
}
nodeIndex += 1
}
i += 1
}
this.newNodeFrom(
newSize = newSize,
newDataMap = newDataMap,
newNodeMap = newNodeMap,
minimumIndex = minimumIndex,
oldDataPassThrough = oldDataPassThrough,
nodesToPassThroughMap = nodesToPassThroughMap,
nodeMigrateToDataTargetMap = nodeMigrateToDataTargetMap,
nodesToMigrateToData = nodesToMigrateToData,
mapOfNewNodes = mapOfNewNodes,
newNodes = newNodes,
newCachedHashCode = newCachedHashCode
)
}
case _: HashCollisionSetNode[A] =>
// this branch should never happen, because HashCollisionSetNodes and BitMapIndexedSetNodes do not occur at the
// same depth
throw new RuntimeException("BitmapIndexedSetNode diff HashCollisionSetNode")
}
/** Utility method only for use in `diff` and `filterImpl`
*
* @param newSize the size of the new SetNode
* @param newDataMap the dataMap of the new SetNode
* @param newNodeMap the nodeMap of the new SetNode
* @param minimumIndex the minimum index (in range of [0, 31]) for which there are sub-nodes or data beneath the new
* SetNode
* @param oldDataPassThrough bitmap representing all the data that are just passed from `this` to the new
* SetNode
* @param nodesToPassThroughMap bitmap representing all nodes that are just passed from `this` to the new SetNode
* @param nodeMigrateToDataTargetMap bitmap representing all positions which will now be data in the new SetNode,
* but which were nodes in `this`
* @param nodesToMigrateToData a queue (in order of child position) of single-element nodes, which will be migrated
* to data, in positions in the `nodeMigrateToDataTargetMap`
* @param mapOfNewNodes bitmap of positions of new nodes to include in the new SetNode
* @param newNodes queue in order of child position, of all new nodes to include in the new SetNode
* @param newCachedHashCode the cached java keyset hashcode of the new SetNode
*/
private[this] def newNodeFrom(
newSize: Int,
newDataMap: Int,
newNodeMap: Int,
minimumIndex: Int,
oldDataPassThrough: Int,
nodesToPassThroughMap: Int,
nodeMigrateToDataTargetMap: Int,
nodesToMigrateToData: mutable.Queue[SetNode[A]],
mapOfNewNodes: Int,
newNodes: mutable.Queue[SetNode[A]],
newCachedHashCode: Int): BitmapIndexedSetNode[A] = {
if (newSize == 0) {
SetNode.empty
} else if (newSize == size) {
this
} else {
val newDataSize = bitCount(newDataMap)
val newContentSize = newDataSize + bitCount(newNodeMap)
val newContent = new Array[Any](newContentSize)
val newOriginalHashes = new Array[Int](newDataSize)
val newAllMap = newDataMap | newNodeMap
val maxIndex = Node.BranchingFactor - Integer.numberOfLeadingZeros(newAllMap)
// note: We MUST start from the minimum index in the old (`this`) node, otherwise `old{Node,Data}Index` will
// not be incremented properly. Otherwise we could have started at Integer.numberOfTrailingZeroes(newAllMap)
var i = minimumIndex
var oldDataIndex = 0
var oldNodeIndex = 0
var newDataIndex = 0
var newNodeIndex = 0
while (i < maxIndex) {
val bitpos = bitposFrom(i)
if ((bitpos & oldDataPassThrough) != 0) {
newContent(newDataIndex) = getPayload(oldDataIndex)
newOriginalHashes(newDataIndex) = getHash(oldDataIndex)
newDataIndex += 1
oldDataIndex += 1
} else if ((bitpos & nodesToPassThroughMap) != 0) {
newContent(newContentSize - newNodeIndex - 1) = getNode(oldNodeIndex)
newNodeIndex += 1
oldNodeIndex += 1
} else if ((bitpos & nodeMigrateToDataTargetMap) != 0) {
// we need not check for null here. If nodeMigrateToDataTargetMap != 0, then nodesMigrateToData must not be null
val node = nodesToMigrateToData.dequeue()
newContent(newDataIndex) = node.getPayload(0)
newOriginalHashes(newDataIndex) = node.getHash(0)
newDataIndex += 1
oldNodeIndex += 1
} else if ((bitpos & mapOfNewNodes) != 0) {
// we need not check for null here. If mapOfNewNodes != 0, then newNodes must not be null
newContent(newContentSize - newNodeIndex - 1) = newNodes.dequeue()
newNodeIndex += 1
oldNodeIndex += 1
} else if ((bitpos & dataMap) != 0) {
oldDataIndex += 1
} else if ((bitpos & nodeMap) != 0) {
oldNodeIndex += 1
}
i += 1
}
new BitmapIndexedSetNode[A](newDataMap, newNodeMap, newContent, newOriginalHashes, newSize, newCachedHashCode)
}
}
override def equals(that: Any): Boolean =
that match {
case node: BitmapIndexedSetNode[_] =>
(this eq node) ||
(this.cachedJavaKeySetHashCode == node.cachedJavaKeySetHashCode) &&
(this.nodeMap == node.nodeMap) &&
(this.dataMap == node.dataMap) &&
(this.size == node.size) &&
java.util.Arrays.equals(this.originalHashes, node.originalHashes) &&
deepContentEquality(this.content, node.content, content.length)
case _ => false
}
@`inline` private def deepContentEquality(a1: Array[Any], a2: Array[Any], length: Int): Boolean = {
if (a1 eq a2)
true
else {
var isEqual = true
var i = 0
while (isEqual && i < length) {
isEqual = a1(i) == a2(i)
i += 1
}
isEqual
}
}
override def hashCode(): Int =
throw new UnsupportedOperationException("Trie nodes do not support hashing.")
override def copy(): BitmapIndexedSetNode[A] = {
val contentClone = content.clone()
val contentLength = contentClone.length
var i = bitCount(dataMap)
while (i < contentLength) {
contentClone(i) = contentClone(i).asInstanceOf[SetNode[A]].copy()
i += 1
}
new BitmapIndexedSetNode[A](dataMap, nodeMap, contentClone, originalHashes.clone(), size, cachedJavaKeySetHashCode)
}
override def concat(that: SetNode[A], shift: Int): BitmapIndexedSetNode[A] = that match {
case bm: BitmapIndexedSetNode[A] =>
if (size == 0) return bm
else if (bm.size == 0 || (bm eq this)) return this
else if (bm.size == 1) {
val originalHash = bm.getHash(0)
return this.updated(bm.getPayload(0), originalHash, improve(originalHash), shift)
}
// if we go through the merge and the result does not differ from `this`, we can just return `this`, to improve sharing
// So, `anyChangesMadeSoFar` will be set to `true` as soon as we encounter a difference between the
// currently-being-computed result, and `this`
var anyChangesMadeSoFar = false
// bitmap containing `1` in any position that has any descendant in either left or right, either data or node
val allMap = dataMap | bm.dataMap | nodeMap | bm.nodeMap
// minimumIndex is inclusive -- it is the first index for which there is data or nodes
val minimumBitPos: Int = Node.bitposFrom(Integer.numberOfTrailingZeros(allMap))
// maximumIndex is inclusive -- it is the last index for which there is data or nodes
// it could not be exclusive, because then upper bound in worst case (Node.BranchingFactor) would be out-of-bound
// of int bitposition representation
val maximumBitPos: Int = Node.bitposFrom(Node.BranchingFactor - Integer.numberOfLeadingZeros(allMap) - 1)
var leftNodeRightNode = 0
var leftDataRightNode = 0
var leftNodeRightData = 0
var leftDataOnly = 0
var rightDataOnly = 0
var leftNodeOnly = 0
var rightNodeOnly = 0
var leftDataRightDataMigrateToNode = 0
var leftDataRightDataLeftOverwrites = 0
var dataToNodeMigrationTargets = 0
{
var bitpos = minimumBitPos
var leftIdx = 0
var rightIdx = 0
var finished = false
while (!finished) {
if ((bitpos & dataMap) != 0) {
if ((bitpos & bm.dataMap) != 0) {
if (getHash(leftIdx) == bm.getHash(rightIdx) && getPayload(leftIdx) == bm.getPayload(rightIdx)) {
leftDataRightDataLeftOverwrites |= bitpos
} else {
leftDataRightDataMigrateToNode |= bitpos
dataToNodeMigrationTargets |= Node.bitposFrom(Node.maskFrom(improve(getHash(leftIdx)), shift))
}
rightIdx += 1
} else if ((bitpos & bm.nodeMap) != 0) {
leftDataRightNode |= bitpos
} else {
leftDataOnly |= bitpos
}
leftIdx += 1
} else if ((bitpos & nodeMap) != 0) {
if ((bitpos & bm.dataMap) != 0) {
leftNodeRightData |= bitpos
rightIdx += 1
} else if ((bitpos & bm.nodeMap) != 0) {
leftNodeRightNode |= bitpos
} else {
leftNodeOnly |= bitpos
}
} else if ((bitpos & bm.dataMap) != 0) {
rightDataOnly |= bitpos
rightIdx += 1
} else if ((bitpos & bm.nodeMap) != 0) {
rightNodeOnly |= bitpos
}
if (bitpos == maximumBitPos) {
finished = true
} else {
bitpos = bitpos << 1
}
}
}
val newDataMap = leftDataOnly | rightDataOnly | leftDataRightDataLeftOverwrites
val newNodeMap =
leftNodeRightNode |
leftDataRightNode |
leftNodeRightData |
leftNodeOnly |
rightNodeOnly |
dataToNodeMigrationTargets
if ((newDataMap == (leftDataOnly | leftDataRightDataLeftOverwrites)) && (newNodeMap == leftNodeOnly)) {
// nothing from `bm` will make it into the result -- return early
return this
}
val newDataSize = bitCount(newDataMap)
val newContentSize = newDataSize + bitCount(newNodeMap)
val newContent = new Array[Any](newContentSize)
val newOriginalHashes = new Array[Int](newDataSize)
var newSize = 0
var newCachedHashCode = 0
{
var leftDataIdx = 0
var rightDataIdx = 0
var leftNodeIdx = 0
var rightNodeIdx = 0
val nextShift = shift + Node.BitPartitionSize
var compressedDataIdx = 0
var compressedNodeIdx = 0
var bitpos = minimumBitPos
var finished = false
while (!finished) {
if ((bitpos & leftNodeRightNode) != 0) {
val leftNode = getNode(leftNodeIdx)
val newNode = leftNode.concat(bm.getNode(rightNodeIdx), nextShift)
if (leftNode ne newNode) {
anyChangesMadeSoFar = true
}
newContent(newContentSize - compressedNodeIdx - 1) = newNode
compressedNodeIdx += 1
rightNodeIdx += 1
leftNodeIdx += 1
newSize += newNode.size
newCachedHashCode += newNode.cachedJavaKeySetHashCode
} else if ((bitpos & leftDataRightNode) != 0) {
anyChangesMadeSoFar = true
val newNode = {
val n = bm.getNode(rightNodeIdx)
val leftPayload = getPayload(leftDataIdx)
val leftOriginalHash = getHash(leftDataIdx)
val leftImproved = improve(leftOriginalHash)
n.updated(leftPayload, leftOriginalHash, leftImproved, nextShift)
}
newContent(newContentSize - compressedNodeIdx - 1) = newNode
compressedNodeIdx += 1
rightNodeIdx += 1
leftDataIdx += 1
newSize += newNode.size
newCachedHashCode += newNode.cachedJavaKeySetHashCode
}
else if ((bitpos & leftNodeRightData) != 0) {
val newNode = {
val rightOriginalHash = bm.getHash(rightDataIdx)
val leftNode = getNode(leftNodeIdx)
val updated = leftNode.updated(
element = bm.getPayload(rightDataIdx),
originalHash = bm.getHash(rightDataIdx),
hash = improve(rightOriginalHash),
shift = nextShift
)
if (updated ne leftNode) {
anyChangesMadeSoFar = true
}
updated
}
newContent(newContentSize - compressedNodeIdx - 1) = newNode
compressedNodeIdx += 1
leftNodeIdx += 1
rightDataIdx += 1
newSize += newNode.size
newCachedHashCode += newNode.cachedJavaKeySetHashCode
} else if ((bitpos & leftDataOnly) != 0) {
val originalHash = originalHashes(leftDataIdx)
newContent(compressedDataIdx) = getPayload(leftDataIdx).asInstanceOf[AnyRef]
newOriginalHashes(compressedDataIdx) = originalHash
compressedDataIdx += 1
leftDataIdx += 1
newSize += 1
newCachedHashCode += improve(originalHash)
} else if ((bitpos & rightDataOnly) != 0) {
anyChangesMadeSoFar = true
val originalHash = bm.originalHashes(rightDataIdx)
newContent(compressedDataIdx) = bm.getPayload(rightDataIdx).asInstanceOf[AnyRef]
newOriginalHashes(compressedDataIdx) = originalHash
compressedDataIdx += 1
rightDataIdx += 1
newSize += 1
newCachedHashCode += improve(originalHash)
} else if ((bitpos & leftNodeOnly) != 0) {
val newNode = getNode(leftNodeIdx)
newContent(newContentSize - compressedNodeIdx - 1) = newNode
compressedNodeIdx += 1
leftNodeIdx += 1
newSize += newNode.size
newCachedHashCode += newNode.cachedJavaKeySetHashCode
} else if ((bitpos & rightNodeOnly) != 0) {
anyChangesMadeSoFar = true
val newNode = bm.getNode(rightNodeIdx)
newContent(newContentSize - compressedNodeIdx - 1) = newNode
compressedNodeIdx += 1
rightNodeIdx += 1
newSize += newNode.size
newCachedHashCode += newNode.cachedJavaKeySetHashCode
} else if ((bitpos & leftDataRightDataMigrateToNode) != 0) {
anyChangesMadeSoFar = true
val newNode = {
val leftOriginalHash = getHash(leftDataIdx)
val rightOriginalHash = bm.getHash(rightDataIdx)
bm.mergeTwoKeyValPairs(
getPayload(leftDataIdx), leftOriginalHash, improve(leftOriginalHash),
bm.getPayload(rightDataIdx), rightOriginalHash, improve(rightOriginalHash),
nextShift
)
}
newContent(newContentSize - compressedNodeIdx - 1) = newNode
compressedNodeIdx += 1
leftDataIdx += 1
rightDataIdx += 1
newSize += newNode.size
newCachedHashCode += newNode.cachedJavaKeySetHashCode
} else if ((bitpos & leftDataRightDataLeftOverwrites) != 0) {
val originalHash = bm.originalHashes(rightDataIdx)
newContent(compressedDataIdx) = bm.getPayload(rightDataIdx).asInstanceOf[AnyRef]
newOriginalHashes(compressedDataIdx) = originalHash
compressedDataIdx += 1
rightDataIdx += 1
newSize += 1
newCachedHashCode += improve(originalHash)
leftDataIdx += 1
}
if (bitpos == maximumBitPos) {
finished = true
} else {
bitpos = bitpos << 1
}
}
}
if (anyChangesMadeSoFar)
new BitmapIndexedSetNode(
dataMap = newDataMap,
nodeMap = newNodeMap,
content = newContent,
originalHashes = newOriginalHashes,
size = newSize,
cachedJavaKeySetHashCode = newCachedHashCode
)
else this
case _ =>
// should never happen -- hash collisions are never at the same level as bitmapIndexedSetNodes
throw new UnsupportedOperationException("Cannot concatenate a HashCollisionSetNode with a BitmapIndexedSetNode")
}
override def foreachWithHash(f: (A, Int) => Unit): Unit = {
val iN = payloadArity // arity doesn't change during this operation
var i = 0
while (i < iN) {
f(getPayload(i), getHash(i))
i += 1
}
val jN = nodeArity // arity doesn't change during this operation
var j = 0
while (j < jN) {
getNode(j).foreachWithHash(f)
j += 1
}
}
override def foreachWithHashWhile(f: (A, Int) => Boolean): Boolean = {
val thisPayloadArity = payloadArity
var pass = true
var i = 0
while (i < thisPayloadArity && pass) {
pass &&= f(getPayload(i), getHash(i))
i += 1
}
val thisNodeArity = nodeArity
var j = 0
while (j < thisNodeArity && pass) {
pass &&= getNode(j).foreachWithHashWhile(f)
j += 1
}
pass
}
}
private final class HashCollisionSetNode[A](val originalHash: Int, val hash: Int, var content: Vector[A]) extends SetNode[A] {
import Node._
require(content.length >= 2)
def contains(element: A, originalHash: Int, hash: Int, shift: Int): Boolean =
this.hash == hash && content.contains(element)
def updated(element: A, originalHash: Int, hash: Int, shift: Int): SetNode[A] =
if (this.contains(element, originalHash, hash, shift)) {
this
} else {
new HashCollisionSetNode[A](originalHash, hash, content.appended(element))
}
/**
* Remove an element from the hash collision node.
*
* When after deletion only one element remains, we return a bit-mapped indexed node with a
* singleton element and a hash-prefix for trie level 0. This node will be then a) either become
* the new root, or b) unwrapped and inlined deeper in the trie.
*/
def removed(element: A, originalHash: Int, hash: Int, shift: Int): SetNode[A] =
if (!this.contains(element, originalHash, hash, shift)) {
this
} else {
val updatedContent = content.filterNot(element0 => element0 == element)
// assert(updatedContent.size == content.size - 1)
updatedContent.size match {
case 1 => new BitmapIndexedSetNode[A](bitposFrom(maskFrom(hash, 0)), 0, Array(updatedContent(0)), Array(originalHash), 1, hash)
case _ => new HashCollisionSetNode[A](originalHash, hash, updatedContent)
}
}
def hasNodes: Boolean = false
def nodeArity: Int = 0
def getNode(index: Int): SetNode[A] =
throw new IndexOutOfBoundsException("No sub-nodes present in hash-collision leaf node.")
def hasPayload: Boolean = true
def payloadArity: Int = content.length
def getPayload(index: Int): A = content(index)
override def getHash(index: Int): Int = originalHash
def size: Int = content.length
def foreach[U](f: A => U): Unit = {
val iter = content.iterator
while (iter.hasNext) {
f(iter.next())
}
}
override def cachedJavaKeySetHashCode: Int = size * hash
def subsetOf(that: SetNode[A], shift: Int): Boolean = if (this eq that) true else that match {
case node: HashCollisionSetNode[A] =>
this.payloadArity <= node.payloadArity && this.content.forall(node.content.contains)
case _ =>
false
}
override def filterImpl(pred: A => Boolean, flipped: Boolean): SetNode[A] = {
val newContent = content.filterImpl(pred, flipped)
val newContentLength = newContent.length
if (newContentLength == 0) {
SetNode.empty
} else if (newContentLength == 1) {
new BitmapIndexedSetNode[A](bitposFrom(maskFrom(hash, 0)), 0, Array(newContent.head), Array(originalHash), 1, hash)
} else if (newContent.length == content.length) this
else new HashCollisionSetNode(originalHash, hash, newContent)
}
override def diff(that: SetNode[A], shift: Int): SetNode[A] =
filterImpl(that.contains(_, originalHash, hash, shift), true)
override def equals(that: Any): Boolean =
that match {
case node: HashCollisionSetNode[_] =>
(this eq node) ||
(this.hash == node.hash) &&
(this.content.size == node.content.size) &&
this.content.forall(node.content.contains)
case _ => false
}
override def hashCode(): Int =
throw new UnsupportedOperationException("Trie nodes do not support hashing.")
override def copy() = new HashCollisionSetNode[A](originalHash, hash, content)
override def concat(that: SetNode[A], shift: Int): SetNode[A] = that match {
case hc: HashCollisionSetNode[A] =>
if (hc eq this) {
this
} else {
var newContent: VectorBuilder[A] = null
val iter = hc.content.iterator
while (iter.hasNext) {
val nextPayload = iter.next()
if (!content.contains(nextPayload)) {
if (newContent eq null) {
newContent = new VectorBuilder()
newContent.addAll(this.content)
}
newContent.addOne(nextPayload)
}
}
if (newContent eq null) this else new HashCollisionSetNode(originalHash, hash, newContent.result())
}
case _: BitmapIndexedSetNode[A] =>
// should never happen -- hash collisions are never at the same level as bitmapIndexedSetNodes
throw new UnsupportedOperationException("Cannot concatenate a HashCollisionSetNode with a BitmapIndexedSetNode")
}
override def foreachWithHash(f: (A, Int) => Unit): Unit = {
val iter = content.iterator
while (iter.hasNext) {
val next = iter.next()
f(next.asInstanceOf[A], originalHash)
}
}
override def foreachWithHashWhile(f: (A, Int) => Boolean): Boolean = {
var stillGoing = true
val iter = content.iterator
while (iter.hasNext && stillGoing) {
val next = iter.next()
stillGoing &&= f(next.asInstanceOf[A], originalHash)
}
stillGoing
}
}
private final class SetIterator[A](rootNode: SetNode[A])
extends ChampBaseIterator[SetNode[A]](rootNode) with Iterator[A] {
def next() = {
if (!hasNext)
throw new NoSuchElementException
val payload = currentValueNode.getPayload(currentValueCursor)
currentValueCursor += 1
payload
}
}
private final class SetReverseIterator[A](rootNode: SetNode[A])
extends ChampBaseReverseIterator[SetNode[A]](rootNode) with Iterator[A] {
def next(): A = {
if (!hasNext)
throw new NoSuchElementException
val payload = currentValueNode.getPayload(currentValueCursor)
currentValueCursor -= 1
payload
}
}
private final class SetHashIterator[A](rootNode: SetNode[A])
extends ChampBaseIterator[SetNode[A]](rootNode) with Iterator[AnyRef] {
private[this] var hash = 0
override def hashCode(): Int = hash
def next(): AnyRef = {
if (!hasNext)
throw new NoSuchElementException
hash = currentValueNode.getHash(currentValueCursor)
currentValueCursor += 1
this
}
}
/**
* $factoryInfo
*
* @define Coll `immutable.HashSet`
* @define coll immutable champ hash set
*/
@SerialVersionUID(3L)
object HashSet extends IterableFactory[HashSet] {
@transient
private final val EmptySet = new HashSet(SetNode.empty)
def empty[A]: HashSet[A] =
EmptySet.asInstanceOf[HashSet[A]]
def from[A](source: collection.IterableOnce[A]): HashSet[A] =
source match {
case hs: HashSet[A] => hs
case _ if source.knownSize == 0 => empty[A]
case _ => (newBuilder[A] ++= source).result()
}
/** Create a new Builder which can be reused after calling `result()` without an
* intermediate call to `clear()` in order to build multiple related results.
*/
def newBuilder[A]: ReusableBuilder[A, HashSet[A]] = new HashSetBuilder
}
/** Builder for HashSet.
* $multipleResults
*/
private[collection] final class HashSetBuilder[A] extends ReusableBuilder[A, HashSet[A]] {
import Node._
import SetNode._
private def newEmptyRootNode = new BitmapIndexedSetNode[A](0, 0, Array.emptyObjectArray.asInstanceOf[Array[Any]], Array.emptyIntArray, 0, 0)
/** The last given out HashSet as a return value of `result()`, if any, otherwise null.
* Indicates that on next add, the elements should be copied to an identical structure, before continuing
* mutations. */
private var aliased: HashSet[A] = _
private def isAliased: Boolean = aliased != null
/** The root node of the partially build hashmap */
private var rootNode: BitmapIndexedSetNode[A] = newEmptyRootNode
/** Inserts element `elem` into array `as` at index `ix`, shifting right the trailing elems */
private def insertElement(as: Array[Int], ix: Int, elem: Int): Array[Int] = {
if (ix < 0) throw new ArrayIndexOutOfBoundsException
if (ix > as.length) throw new ArrayIndexOutOfBoundsException
val result = new Array[Int](as.length + 1)
arraycopy(as, 0, result, 0, ix)
result(ix) = elem
arraycopy(as, ix, result, ix + 1, as.length - ix)
result
}
/** Inserts key-value into the bitmapIndexMapNode. Requires that this is a new key-value pair */
private def insertValue[A1 >: A](bm: BitmapIndexedSetNode[A], bitpos: Int, key: A, originalHash: Int, keyHash: Int): Unit = {
val dataIx = bm.dataIndex(bitpos)
val idx = TupleLength * dataIx
val src = bm.content
val dst = new Array[Any](src.length + TupleLength)
// copy 'src' and insert 2 element(s) at position 'idx'
arraycopy(src, 0, dst, 0, idx)
dst(idx) = key
arraycopy(src, idx, dst, idx + TupleLength, src.length - idx)
val dstHashes = insertElement(bm.originalHashes, dataIx, originalHash)
bm.dataMap = bm.dataMap | bitpos
bm.content = dst
bm.originalHashes = dstHashes
bm.size += 1
bm.cachedJavaKeySetHashCode += keyHash
}
/** Mutates `bm` to replace inline data at bit position `bitpos` with updated key/value */
private def setValue[A1 >: A](bm: BitmapIndexedSetNode[A], bitpos: Int, elem: A): Unit = {
val dataIx = bm.dataIndex(bitpos)
val idx = TupleLength * dataIx
bm.content(idx) = elem
}
def update(setNode: SetNode[A], element: A, originalHash: Int, elementHash: Int, shift: Int): Unit =
setNode match {
case bm: BitmapIndexedSetNode[A] =>
val mask = maskFrom(elementHash, shift)
val bitpos = bitposFrom(mask)
if ((bm.dataMap & bitpos) != 0) {
val index = indexFrom(bm.dataMap, mask, bitpos)
val element0 = bm.getPayload(index)
val element0UnimprovedHash = bm.getHash(index)
if (element0UnimprovedHash == originalHash && element0 == element) {
setValue(bm, bitpos, element0)
} else {
val element0Hash = improve(element0UnimprovedHash)
val subNodeNew = bm.mergeTwoKeyValPairs(element0, element0UnimprovedHash, element0Hash, element, originalHash, elementHash, shift + BitPartitionSize)
bm.migrateFromInlineToNodeInPlace(bitpos, element0Hash, subNodeNew)
}
} else if ((bm.nodeMap & bitpos) != 0) {
val index = indexFrom(bm.nodeMap, mask, bitpos)
val subNode = bm.getNode(index)
val beforeSize = subNode.size
val beforeHashCode = subNode.cachedJavaKeySetHashCode
update(subNode, element, originalHash, elementHash, shift + BitPartitionSize)
bm.size += subNode.size - beforeSize
bm.cachedJavaKeySetHashCode += subNode.cachedJavaKeySetHashCode - beforeHashCode
} else {
insertValue(bm, bitpos, element, originalHash, elementHash)
}
case hc: HashCollisionSetNode[A] =>
val index = hc.content.indexOf(element)
if (index < 0) {
hc.content = hc.content.appended(element)
} else {
hc.content = hc.content.updated(index, element)
}
}
/** If currently referencing aliased structure, copy elements to new mutable structure */
private def ensureUnaliased():Unit = {
if (isAliased) copyElems()
aliased = null
}
/** Copy elements to new mutable structure */
private def copyElems(): Unit = {
rootNode = rootNode.copy()
}
override def result(): HashSet[A] =
if (rootNode.size == 0) {
HashSet.empty
} else if (aliased != null) {
aliased
} else {
aliased = new HashSet(rootNode)
releaseFence()
aliased
}
override def addOne(elem: A): this.type = {
ensureUnaliased()
val h = elem.##
val im = improve(h)
update(rootNode, elem, h, im, 0)
this
}
override def addAll(xs: IterableOnce[A]) = {
ensureUnaliased()
xs match {
case hm: HashSet[A] =>
new ChampBaseIterator[SetNode[A]](hm.rootNode) {
while(hasNext) {
val originalHash = currentValueNode.getHash(currentValueCursor)
update(
setNode = rootNode,
element = currentValueNode.getPayload(currentValueCursor),
originalHash = originalHash,
elementHash = improve(originalHash),
shift = 0
)
currentValueCursor += 1
}
}
case other =>
val it = other.iterator
while(it.hasNext) addOne(it.next())
}
this
}
override def clear(): Unit = {
aliased = null
if (rootNode.size > 0) {
// if rootNode is empty, we will not have given it away anyways, we instead give out the reused Set.empty
rootNode = newEmptyRootNode
}
}
private[collection] def size: Int = rootNode.size
override def knownSize: Int = rootNode.size
}
