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Standard library for the Scala Programming Language
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala
package collection
package immutable
import scala.annotation.unchecked.{ uncheckedVariance => uV }
import generic._
import scala.collection.parallel.immutable.ParHashSet
/** This class implements immutable sets using a hash trie.
*
* '''Note:''' The builder of this hash set may return specialized representations for small sets.
*
* @tparam A the type of the elements contained in this hash set.
*
* @author Martin Odersky
* @author Tiark Rompf
* @version 2.8
* @since 2.3
* @define Coll `immutable.HashSet`
* @define coll immutable hash set
*/
@SerialVersionUID(2L)
class HashSet[A] extends AbstractSet[A]
with Set[A]
with GenericSetTemplate[A, HashSet]
with SetLike[A, HashSet[A]]
with CustomParallelizable[A, ParHashSet[A]]
with Serializable
{
override def companion: GenericCompanion[HashSet] = HashSet
//class HashSet[A] extends Set[A] with SetLike[A, HashSet[A]] {
override def par = ParHashSet.fromTrie(this)
override def size: Int = 0
override def empty = HashSet.empty[A]
def iterator: Iterator[A] = Iterator.empty
override def foreach[U](f: A => U): Unit = { }
def contains(e: A): Boolean = get0(e, computeHash(e), 0)
override def + (e: A): HashSet[A] = updated0(e, computeHash(e), 0)
override def + (elem1: A, elem2: A, elems: A*): HashSet[A] =
this + elem1 + elem2 ++ elems
// TODO: optimize (might be able to use mutable updates)
def - (e: A): HashSet[A] =
removed0(e, computeHash(e), 0)
protected def elemHashCode(key: A) = key.##
protected final def improve(hcode: Int) = {
var h: Int = hcode + ~(hcode << 9)
h = h ^ (h >>> 14)
h = h + (h << 4)
h ^ (h >>> 10)
}
private[collection] def computeHash(key: A) = improve(elemHashCode(key))
protected def get0(key: A, hash: Int, level: Int): Boolean = false
def updated0(key: A, hash: Int, level: Int): HashSet[A] =
new HashSet.HashSet1(key, hash)
protected def removed0(key: A, hash: Int, level: Int): HashSet[A] = this
protected def writeReplace(): AnyRef = new HashSet.SerializationProxy(this)
}
/** $factoryInfo
* @define Coll `immutable.HashSet`
* @define coll immutable hash set
*
* @author Tiark Rompf
* @since 2.3
* @define Coll `immutable.HashSet`
* @define coll immutable hash set
* @define mayNotTerminateInf
* @define willNotTerminateInf
*/
object HashSet extends ImmutableSetFactory[HashSet] {
/** $setCanBuildFromInfo */
implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, HashSet[A]] = setCanBuildFrom[A]
override def empty[A]: HashSet[A] = EmptyHashSet.asInstanceOf[HashSet[A]]
private object EmptyHashSet extends HashSet[Any] { }
// utility method to create a HashTrieSet from two leaf HashSets (HashSet1 or HashSetCollision1) with non-colliding hash code)
private def makeHashTrieSet[A](hash0:Int, elem0:HashSet[A], hash1:Int, elem1:HashSet[A], level:Int) : HashTrieSet[A] = {
val index0 = (hash0 >>> level) & 0x1f
val index1 = (hash1 >>> level) & 0x1f
if(index0 != index1) {
val bitmap = (1 << index0) | (1 << index1)
val elems = new Array[HashSet[A]](2)
if(index0 < index1) {
elems(0) = elem0
elems(1) = elem1
} else {
elems(0) = elem1
elems(1) = elem0
}
new HashTrieSet[A](bitmap, elems, elem0.size + elem1.size)
} else {
val elems = new Array[HashSet[A]](1)
val bitmap = (1 << index0)
val child = makeHashTrieSet(hash0, elem0, hash1, elem1, level + 5)
elems(0) = child
new HashTrieSet[A](bitmap, elems, child.size)
}
}
// TODO: add HashSet2, HashSet3, ...
class HashSet1[A](private[HashSet] val key: A, private[HashSet] val hash: Int) extends HashSet[A] {
override def size = 1
override def get0(key: A, hash: Int, level: Int): Boolean =
(hash == this.hash && key == this.key)
override def updated0(key: A, hash: Int, level: Int): HashSet[A] =
if (hash == this.hash && key == this.key) this
else {
if (hash != this.hash) {
makeHashTrieSet(this.hash, this, hash, new HashSet1(key, hash), level)
} else {
// 32-bit hash collision (rare, but not impossible)
new HashSetCollision1(hash, ListSet.empty + this.key + key)
}
}
override def removed0(key: A, hash: Int, level: Int): HashSet[A] =
if (hash == this.hash && key == this.key) HashSet.empty[A] else this
override def iterator: Iterator[A] = Iterator(key)
override def foreach[U](f: A => U): Unit = f(key)
}
private[immutable] class HashSetCollision1[A](private[HashSet] val hash: Int, val ks: ListSet[A])
extends HashSet[A] {
override def size = ks.size
override def get0(key: A, hash: Int, level: Int): Boolean =
if (hash == this.hash) ks.contains(key) else false
override def updated0(key: A, hash: Int, level: Int): HashSet[A] =
if (hash == this.hash) new HashSetCollision1(hash, ks + key)
else makeHashTrieSet(this.hash, this, hash, new HashSet1(key, hash), level)
override def removed0(key: A, hash: Int, level: Int): HashSet[A] =
if (hash == this.hash) {
val ks1 = ks - key
if(ks1.isEmpty)
HashSet.empty[A]
else if(ks1.tail.isEmpty)
new HashSet1(ks1.head, hash)
else
new HashSetCollision1(hash, ks1)
} else this
override def iterator: Iterator[A] = ks.iterator
override def foreach[U](f: A => U): Unit = ks.foreach(f)
private def writeObject(out: java.io.ObjectOutputStream) {
// this cannot work - reading things in might produce different
// hash codes and remove the collision. however this is never called
// because no references to this class are ever handed out to client code
// and HashTrieSet serialization takes care of the situation
sys.error("cannot serialize an immutable.HashSet where all items have the same 32-bit hash code")
//out.writeObject(kvs)
}
private def readObject(in: java.io.ObjectInputStream) {
sys.error("cannot deserialize an immutable.HashSet where all items have the same 32-bit hash code")
//kvs = in.readObject().asInstanceOf[ListSet[A]]
//hash = computeHash(kvs.)
}
}
class HashTrieSet[A](private val bitmap: Int, private[collection] val elems: Array[HashSet[A]], private val size0: Int)
extends HashSet[A] {
assert(Integer.bitCount(bitmap) == elems.length)
// assertion has to remain disabled until SI-6197 is solved
// assert(elems.length > 1 || (elems.length == 1 && elems(0).isInstanceOf[HashTrieSet[_]]))
override def size = size0
override def get0(key: A, hash: Int, level: Int): Boolean = {
val index = (hash >>> level) & 0x1f
val mask = (1 << index)
if (bitmap == - 1) {
elems(index & 0x1f).get0(key, hash, level + 5)
} else if ((bitmap & mask) != 0) {
val offset = Integer.bitCount(bitmap & (mask-1))
// TODO: might be worth checking if sub is HashTrieSet (-> monomorphic call site)
elems(offset).get0(key, hash, level + 5)
} else
false
}
override def updated0(key: A, hash: Int, level: Int): HashSet[A] = {
val index = (hash >>> level) & 0x1f
val mask = (1 << index)
val offset = Integer.bitCount(bitmap & (mask-1))
if ((bitmap & mask) != 0) {
// TODO: might be worth checking if sub is HashTrieSet (-> monomorphic call site)
val sub = elems(offset)
val subNew = sub.updated0(key, hash, level + 5)
if (sub eq subNew) this
else {
val elemsNew = new Array[HashSet[A]](elems.length)
Array.copy(elems, 0, elemsNew, 0, elems.length)
elemsNew(offset) = subNew
new HashTrieSet(bitmap, elemsNew, size + (subNew.size - sub.size))
}
} else {
val elemsNew = new Array[HashSet[A]](elems.length + 1)
Array.copy(elems, 0, elemsNew, 0, offset)
elemsNew(offset) = new HashSet1(key, hash)
Array.copy(elems, offset, elemsNew, offset + 1, elems.length - offset)
val bitmapNew = bitmap | mask
new HashTrieSet(bitmapNew, elemsNew, size + 1)
}
}
override def removed0(key: A, hash: Int, level: Int): HashSet[A] = {
val index = (hash >>> level) & 0x1f
val mask = (1 << index)
val offset = Integer.bitCount(bitmap & (mask-1))
if ((bitmap & mask) != 0) {
val sub = elems(offset)
// TODO: might be worth checking if sub is HashTrieMap (-> monomorphic call site)
val subNew = sub.removed0(key, hash, level + 5)
if (sub eq subNew) this
else if (subNew.isEmpty) {
val bitmapNew = bitmap ^ mask
if (bitmapNew != 0) {
val elemsNew = new Array[HashSet[A]](elems.length - 1)
Array.copy(elems, 0, elemsNew, 0, offset)
Array.copy(elems, offset + 1, elemsNew, offset, elems.length - offset - 1)
val sizeNew = size - sub.size
// if we have only one child, which is not a HashTrieSet but a self-contained set like
// HashSet1 or HashSetCollision1, return the child instead
if (elemsNew.length == 1 && !elemsNew(0).isInstanceOf[HashTrieSet[_]])
elemsNew(0)
else
new HashTrieSet(bitmapNew, elemsNew, sizeNew)
} else
HashSet.empty[A]
} else {
val elemsNew = new Array[HashSet[A]](elems.length)
Array.copy(elems, 0, elemsNew, 0, elems.length)
elemsNew(offset) = subNew
val sizeNew = size + (subNew.size - sub.size)
new HashTrieSet(bitmap, elemsNew, sizeNew)
}
} else {
this
}
}
override def iterator = new TrieIterator[A](elems.asInstanceOf[Array[Iterable[A]]]) {
final override def getElem(cc: AnyRef): A = cc.asInstanceOf[HashSet1[A]].key
}
/*
def time(block: =>Unit) = { val t0 = System.nanoTime; block; println("elapsed: " + (System.nanoTime - t0)/1000000.0) }
var mOld = OldHashSet.empty[Int]
var mNew = HashSet.empty[Int]
time { for (i <- 0 until 100000) mOld = mOld + i }
time { for (i <- 0 until 100000) mOld = mOld + i }
time { for (i <- 0 until 100000) mOld = mOld + i }
time { for (i <- 0 until 100000) mNew = mNew + i }
time { for (i <- 0 until 100000) mNew = mNew + i }
time { for (i <- 0 until 100000) mNew = mNew + i }
time { mOld.iterator.foreach( p => ()) }
time { mOld.iterator.foreach( p => ()) }
time { mOld.iterator.foreach( p => ()) }
time { mNew.iterator.foreach( p => ()) }
time { mNew.iterator.foreach( p => ()) }
time { mNew.iterator.foreach( p => ()) }
*/
override def foreach[U](f: A => U): Unit = {
var i = 0;
while (i < elems.length) {
elems(i).foreach(f)
i += 1
}
}
}
@SerialVersionUID(2L) private class SerializationProxy[A,B](@transient private var orig: HashSet[A]) extends Serializable {
private def writeObject(out: java.io.ObjectOutputStream) {
val s = orig.size
out.writeInt(s)
for (e <- orig) {
out.writeObject(e)
}
}
private def readObject(in: java.io.ObjectInputStream) {
orig = empty
val s = in.readInt()
for (i <- 0 until s) {
val e = in.readObject().asInstanceOf[A]
orig = orig + e
}
}
private def readResolve(): AnyRef = orig
}
}