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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2010, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection
package immutable
import generic._
import BitSetLike.{LogWL, updateArray}
/** A base class for immutable bit sets.
*
* @since 1
*/
@serializable @SerialVersionUID(1611436763290191562L)
abstract class BitSet extends Set[Int]
with scala.collection.BitSet
with BitSetLike[BitSet] {
override def empty = BitSet.empty
def fromArray(elems: Array[Long]): BitSet = BitSet.fromArray(elems)
/** Update word at index <code>idx</code>; enlarge set if <code>idx</code>
* 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)
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)
if (contains(elem)) {
val idx = elem >> LogWL
updateWord(idx, word(idx) & ~(1L << elem))
} else this
}
}
/** A factory object for bitsets */
object BitSet extends BitSetFactory[BitSet] {
/** The empty bitset */
val empty: BitSet = new BitSet1(0L)
implicit def canBuildFrom: CanBuildFrom[BitSet, Int, BitSet] = bitsetCanBuildFrom
/** A bitset containing all the bits in an array */
def fromArray(elems: Array[Long]): BitSet = {
val len = elems.length
if (len == 0) empty
else if (len == 1) new BitSet1(elems(0))
else if (len == 2) new BitSet2(elems(0), elems(1))
else new BitSetN(elems)
}
private val hashSeed = "BitSet".hashCode
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) new BitSet2(elems, w)
else fromArray(updateArray(Array(elems), idx, w))
}
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) new BitSet2(elems0, w)
else fromArray(updateArray(Array(elems0, elems1), idx, w))
}
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 = fromArray(updateArray(elems, idx, w))
}
}
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