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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 immutable
import generic._
import BitSetLike.{LogWL, updateArray}
import mutable.Builder
/** A class for immutable bitsets.
* $bitsetinfo
* @see [[http://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
*/
@SerialVersionUID(1611436763290191562L)
abstract class BitSet extends scala.collection.AbstractSet[Int]
with SortedSet[Int]
with scala.collection.BitSet
with BitSetLike[BitSet]
with Serializable {
override def empty = BitSet.empty
protected def fromBitMaskNoCopy(elems: Array[Long]): BitSet = BitSet.fromBitMaskNoCopy(elems)
/** Update word at index `idx`; enlarge set if `idx` outside range of set.
*/
protected def updateWord(idx: Int, w: Long): BitSet
/** Adds element to bitset, returning a new set.
*/
def + (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))
}
}
/** Removes element from bitset, returning a new set
*/
def - (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
}
}
/** $factoryInfo
* @define Coll `immutable.BitSet`
* @define coll immutable bitset
*/
object BitSet extends BitSetFactory[BitSet] {
/** The empty bitset */
val empty: BitSet = new BitSet1(0L)
private def createSmall(a: Long, b: Long): BitSet = if (b == 0L) new BitSet1(a) else new BitSet2(a, b)
/** A builder that takes advantage of mutable BitSets. */
def newBuilder: Builder[Int, BitSet] = new Builder[Int, BitSet] {
private[this] val b = new mutable.BitSet
def += (x: Int) = { b += x; this }
def clear() = b.clear()
def result() = b.toImmutable
}
/** $bitsetCanBuildFrom */
implicit val canBuildFrom: CanBuildFrom[BitSet, Int, BitSet] = bitsetCanBuildFrom
/** 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 = new Array[Long](len)
Array.copy(elems, 0, a, 0, 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)
}
@SerialVersionUID(2260107458435649300L)
class BitSet1(val elems: Long) extends BitSet {
protected def nwords = 1
protected def word(idx: Int) = if (idx == 0) elems else 0L
protected def updateWord(idx: Int, w: Long): BitSet =
if (idx == 0) new BitSet1(w)
else if (idx == 1) createSmall(elems, w)
else fromBitMaskNoCopy(updateArray(Array(elems), idx, w))
override def head: Int =
if (elems == 0L) throw new NoSuchElementException("Empty BitSet")
else java.lang.Long.numberOfTrailingZeros(elems)
override def tail: BitSet =
if (elems == 0L) throw new NoSuchElementException("Empty BitSet")
else new BitSet1(elems - java.lang.Long.lowestOneBit(elems))
}
@SerialVersionUID(-860417644893387539L)
class BitSet2(val elems0: Long, elems1: Long) extends BitSet {
protected def nwords = 2
protected def word(idx: Int) = if (idx == 0) elems0 else if (idx == 1) elems1 else 0L
protected def updateWord(idx: Int, w: Long): BitSet =
if (idx == 0) new BitSet2(w, elems1)
else if (idx == 1) createSmall(elems0, w)
else fromBitMaskNoCopy(updateArray(Array(elems0, elems1), idx, w))
override def head: Int =
if (elems0 == 0L) {
if (elems1 == 0) throw new NoSuchElementException("Empty BitSet")
64 + java.lang.Long.numberOfTrailingZeros(elems1)
}
else java.lang.Long.numberOfTrailingZeros(elems0)
override def tail: BitSet =
if (elems0 == 0L) {
if (elems1 == 0L) throw new NoSuchElementException("Empty BitSet")
createSmall(elems0, elems1 - java.lang.Long.lowestOneBit(elems1))
}
else new BitSet2(elems0 - java.lang.Long.lowestOneBit(elems0), elems1)
}
/** The implementing class for bit sets with elements >= 128 (exceeding
* the capacity of two long values). The constructor wraps an existing
* bit mask without copying, thus exposing a mutable part of the internal
* implementation. Care needs to be taken not to modify the exposed
* array.
*/
@SerialVersionUID(807040099560956194L)
class BitSetN(val elems: Array[Long]) extends BitSet {
protected def nwords = elems.length
protected def word(idx: Int) = if (idx < nwords) elems(idx) else 0L
protected def updateWord(idx: Int, w: Long): BitSet = fromBitMaskNoCopy(updateArray(elems, idx, w))
override def tail: BitSet = {
val n = nwords
var i = 0
while (i < n) {
val wi = word(i)
if (wi != 0L) return fromBitMaskNoCopy(updateArray(elems, i, wi - java.lang.Long.lowestOneBit(wi)))
i += 1
}
throw new NoSuchElementException("Empty BitSet")
}
}
}
