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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
package immutable
import BitSetOps.{LogWL, updateArray}
import mutable.Builder
import scala.annotation.{implicitNotFound, nowarn}
/** A class for immutable bitsets.
* $bitsetinfo
* @see [[https://docs.scala-lang.org/overviews/collections/concrete-immutable-collection-classes.html#immutable-bitsets "Scala's Collection Library overview"]]
* section on `Immutable BitSets` for more information.
*
* @define Coll `immutable.BitSet`
* @define coll immutable bitset
*/
sealed abstract class BitSet
extends AbstractSet[Int]
with SortedSet[Int]
with SortedSetOps[Int, SortedSet, BitSet]
with StrictOptimizedSortedSetOps[Int, SortedSet, BitSet]
with collection.BitSet
with collection.BitSetOps[BitSet]
with Serializable {
override def unsorted: Set[Int] = this
override protected def fromSpecific(coll: IterableOnce[Int]): BitSet = bitSetFactory.fromSpecific(coll)
override protected def newSpecificBuilder: Builder[Int, BitSet] = bitSetFactory.newBuilder
override def empty: BitSet = bitSetFactory.empty
def bitSetFactory = BitSet
protected[collection] def fromBitMaskNoCopy(elems: Array[Long]): BitSet = BitSet.fromBitMaskNoCopy(elems)
def incl(elem: Int): BitSet = {
require(elem >= 0, "bitset element must be >= 0")
if (contains(elem)) this
else {
val idx = elem >> LogWL
updateWord(idx, word(idx) | (1L << elem))
}
}
def excl(elem: Int): BitSet = {
require(elem >= 0, "bitset element must be >= 0")
if (contains(elem)) {
val idx = elem >> LogWL
updateWord(idx, word(idx) & ~(1L << elem))
} else this
}
/** Update word at index `idx`; enlarge set if `idx` outside range of set.
*/
protected def updateWord(idx: Int, w: Long): BitSet
override def map(f: Int => Int): BitSet = strictOptimizedMap(newSpecificBuilder, f)
override def map[B](f: Int => B)(implicit @implicitNotFound(collection.BitSet.ordMsg) ev: Ordering[B]): SortedSet[B] =
super[StrictOptimizedSortedSetOps].map(f)
override def flatMap(f: Int => IterableOnce[Int]): BitSet = strictOptimizedFlatMap(newSpecificBuilder, f)
override def flatMap[B](f: Int => IterableOnce[B])(implicit @implicitNotFound(collection.BitSet.ordMsg) ev: Ordering[B]): SortedSet[B] =
super[StrictOptimizedSortedSetOps].flatMap(f)
override def collect(pf: PartialFunction[Int, Int]): BitSet = strictOptimizedCollect(newSpecificBuilder, pf)
override def collect[B](pf: scala.PartialFunction[Int, B])(implicit @implicitNotFound(collection.BitSet.ordMsg) ev: Ordering[B]): SortedSet[B] =
super[StrictOptimizedSortedSetOps].collect(pf)
// necessary for disambiguation
override def zip[B](that: scala.IterableOnce[B])(implicit @implicitNotFound(collection.BitSet.zipOrdMsg) ev: Ordering[(Int, B)]): SortedSet[(Int, B)] =
super.zip(that)
protected[this] def writeReplace(): AnyRef = new BitSet.SerializationProxy(this)
}
/**
* $factoryInfo
* @define Coll `immutable.BitSet`
* @define coll immutable bitset
*/
@nowarn("cat=deprecation&msg=Implementation classes of BitSet should not be accessed directly")
@SerialVersionUID(3L)
object BitSet extends SpecificIterableFactory[Int, BitSet] {
def fromSpecific(it: scala.collection.IterableOnce[Int]): BitSet =
it match {
case bs: BitSet => bs
case _ => (newBuilder ++= it).result()
}
final val empty: BitSet = new BitSet1(0L)
def newBuilder: Builder[Int, BitSet] =
mutable.BitSet.newBuilder.mapResult(bs => fromBitMaskNoCopy(bs.elems))
private def createSmall(a: Long, b: Long): BitSet = if (b == 0L) new BitSet1(a) else new BitSet2(a, b)
/** A bitset containing all the bits in an array */
def fromBitMask(elems: Array[Long]): BitSet = {
val len = elems.length
if (len == 0) empty
else if (len == 1) new BitSet1(elems(0))
else if (len == 2) createSmall(elems(0), elems(1))
else {
val a = java.util.Arrays.copyOf(elems, len)
new BitSetN(a)
}
}
/** A bitset containing all the bits in an array, wrapping the existing
* array without copying.
*/
def fromBitMaskNoCopy(elems: Array[Long]): BitSet = {
val len = elems.length
if (len == 0) empty
else if (len == 1) new BitSet1(elems(0))
else if (len == 2) createSmall(elems(0), elems(1))
else new BitSetN(elems)
}
@deprecated("Implementation classes of BitSet should not be accessed directly", "2.13.0")
class BitSet1(val elems: Long) extends BitSet {
protected[collection] def nwords = 1
protected[collection] def word(idx: Int) = if (idx == 0) elems else 0L
protected[collection] def updateWord(idx: Int, w: Long): BitSet =
if (idx == 0) new BitSet1(w)
else if (idx == 1) createSmall(elems, w)
else this.fromBitMaskNoCopy(updateArray(Array(elems), idx, w))
override def diff(other: collection.Set[Int]): BitSet = other match {
case bs: collection.BitSet => bs.nwords match {
case 0 => this
case _ =>
val newElems = elems & ~bs.word(0)
if (newElems == 0L) this.empty else new BitSet1(newElems)
}
case _ => super.diff(other)
}
override def filterImpl(pred: Int => Boolean, isFlipped: Boolean): BitSet = {
val _elems = BitSetOps.computeWordForFilter(pred, isFlipped, elems, 0)
if (_elems == 0L) this.empty else new BitSet1(_elems)
}
}
@deprecated("Implementation classes of BitSet should not be accessed directly", "2.13.0")
class BitSet2(val elems0: Long, val elems1: Long) extends BitSet {
protected[collection] def nwords = 2
protected[collection] def word(idx: Int) = if (idx == 0) elems0 else if (idx == 1) elems1 else 0L
protected[collection] def updateWord(idx: Int, w: Long): BitSet =
if (idx == 0) new BitSet2(w, elems1)
else if (idx == 1) createSmall(elems0, w)
else this.fromBitMaskNoCopy(updateArray(Array(elems0, elems1), idx, w))
override def diff(other: collection.Set[Int]): BitSet = other match {
case bs: collection.BitSet => bs.nwords match {
case 0 => this
case 1 =>
new BitSet2(elems0 & ~bs.word(0), elems1)
case _ =>
val _elems0 = elems0 & ~bs.word(0)
val _elems1 = elems1 & ~bs.word(1)
if (_elems1 == 0L) {
if (_elems0 == 0L) {
this.empty
} else {
new BitSet1(_elems0)
}
} else {
new BitSet2(_elems0, _elems1)
}
}
case _ => super.diff(other)
}
override def filterImpl(pred: Int => Boolean, isFlipped: Boolean): BitSet = {
val _elems0 = BitSetOps.computeWordForFilter(pred, isFlipped, elems0, 0)
val _elems1 = BitSetOps.computeWordForFilter(pred, isFlipped, elems1, 1)
if (_elems1 == 0L) {
if (_elems0 == 0L) {
this.empty
}
else new BitSet1(_elems0)
}
else new BitSet2(_elems0, _elems1)
}
}
@deprecated("Implementation classes of BitSet should not be accessed directly", "2.13.0")
class BitSetN(val elems: Array[Long]) extends BitSet {
protected[collection] def nwords = elems.length
protected[collection] def word(idx: Int) = if (idx < nwords) elems(idx) else 0L
protected[collection] def updateWord(idx: Int, w: Long): BitSet = this.fromBitMaskNoCopy(updateArray(elems, idx, w))
override def diff(that: collection.Set[Int]): BitSet = that match {
case bs: collection.BitSet =>
/*
* Algorithm:
*
* We iterate, word-by-word, backwards from the shortest of the two bitsets (this, or bs) i.e. the one with
* the fewer words. Two extra concerns for optimization are described below.
*
* Array Shrinking:
* If `this` is not longer than `bs`, then since we must iterate through the full array of words,
* we can track the new highest index word which is non-zero, at little additional cost. At the end, the new
* Array[Long] allocated for the returned BitSet will only be of size `maxNonZeroIndex + 1`
*
* Tracking Changes:
* If the two sets are disjoint, then we can return `this`. Therefor, until at least one change is detected,
* we check each word for if it has changed from its corresponding word in `this`. Once a single change is
* detected, we stop checking because the cost of the new Array must be paid anyways.
*/
val bsnwords = bs.nwords
val thisnwords = nwords
if (bsnwords >= thisnwords) {
// here, we may have opportunity to shrink the size of the array
// so, track the highest index which is non-zero. That ( + 1 ) will be our new array length
var i = thisnwords - 1
var currentWord = 0L
// if there are never any changes, we can return `this` at the end
var anyChanges = false
while (i >= 0 && currentWord == 0L) {
val oldWord = word(i)
currentWord = oldWord & ~bs.word(i)
anyChanges ||= currentWord != oldWord
i -= 1
}
if (i < 0) {
// all indices >= 0 have had result 0, so the bitset is empty
this.empty
} else {
val minimumNonZeroIndex: Int = i + 1
while (!anyChanges && i >= 0) {
val oldWord = word(i)
currentWord = oldWord & ~bs.word(i)
anyChanges ||= currentWord != oldWord
i -= 1
}
if (anyChanges) {
if (minimumNonZeroIndex == -1) {
this.empty
} else if (minimumNonZeroIndex == 0) {
new BitSet1(currentWord)
} else if (minimumNonZeroIndex == 1) {
new BitSet2(word(0) & ~bs.word(0), currentWord)
} else {
val newArray = elems.take(minimumNonZeroIndex + 1)
newArray(i + 1) = currentWord
while (i >= 0) {
newArray(i) = word(i) & ~bs.word(i)
i -= 1
}
this.fromBitMaskNoCopy(newArray)
}
} else {
this
}
}
} else {
var i = bsnwords - 1
var anyChanges = false
var currentWord = 0L
while (i >= 0 && !anyChanges) {
val oldWord = word(i)
currentWord = oldWord & ~bs.word(i)
anyChanges ||= currentWord != oldWord
i -= 1
}
if (anyChanges) {
val newElems = elems.clone()
newElems(i + 1) = currentWord
while (i >= 0) {
newElems(i) = word(i) & ~bs.word(i)
i -= 1
}
this.fromBitMaskNoCopy(newElems)
} else {
this
}
}
case _ => super.diff(that)
}
override def filterImpl(pred: Int => Boolean, isFlipped: Boolean): BitSet = {
// here, we may have opportunity to shrink the size of the array
// so, track the highest index which is non-zero. That ( + 1 ) will be our new array length
var i = nwords - 1
var currentWord = 0L
// if there are never any changes, we can return `this` at the end
var anyChanges = false
while (i >= 0 && currentWord == 0L) {
val oldWord = word(i)
currentWord = BitSetOps.computeWordForFilter(pred, isFlipped, oldWord, i)
anyChanges ||= currentWord != oldWord
i -= 1
}
if (i < 0) {
// all indices >= 0 have had result 0, so the bitset is empty
if (currentWord == 0) this.empty else this.fromBitMaskNoCopy(Array(currentWord))
} else {
val minimumNonZeroIndex: Int = i + 1
while (!anyChanges && i >= 0) {
val oldWord = word(i)
currentWord = BitSetOps.computeWordForFilter(pred, isFlipped, oldWord, i)
anyChanges ||= currentWord != oldWord
i -= 1
}
if (anyChanges) {
if (minimumNonZeroIndex == -1) {
this.empty
} else if (minimumNonZeroIndex == 0) {
new BitSet1(currentWord)
} else if (minimumNonZeroIndex == 1) {
new BitSet2(BitSetOps.computeWordForFilter(pred, isFlipped, word(0), 0), currentWord)
} else {
val newArray = elems.take(minimumNonZeroIndex + 1)
newArray(i + 1) = currentWord
while (i >= 0) {
newArray(i) = BitSetOps.computeWordForFilter(pred, isFlipped, word(i), i)
i -= 1
}
this.fromBitMaskNoCopy(newArray)
}
} else {
this
}
}
}
override def toBitMask: Array[Long] = elems.clone()
}
@SerialVersionUID(3L)
private final class SerializationProxy(coll: BitSet) extends scala.collection.BitSet.SerializationProxy(coll) {
protected[this] def readResolve(): Any = BitSet.fromBitMaskNoCopy(elems)
}
}