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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 mutable
import generic.CanBuildFrom
/** This class implements mutable maps with `AnyRef` keys based on a hash table with open addressing.
*
* Basic map operations on single entries, including `contains` and `get`,
* are typically significantly faster with `AnyRefMap` than [[HashMap]].
* Note that numbers and characters are not handled specially in AnyRefMap;
* only plain `equals` and `hashCode` are used in comparisons.
*
* Methods that traverse or regenerate the map, including `foreach` and `map`,
* are not in general faster than with `HashMap`. The methods `foreachKey`,
* `foreachValue`, `mapValuesNow`, and `transformValues` are, however, faster
* than alternative ways to achieve the same functionality.
*
* Maps with open addressing may become less efficient at lookup after
* repeated addition/removal of elements. Although `AnyRefMap` makes a
* decent attempt to remain efficient regardless, calling `repack`
* on a map that will no longer have elements removed but will be
* used heavily may save both time and storage space.
*
* This map is not intended to contain more than 2^29^ entries (approximately
* 500 million). The maximum capacity is 2^30^, but performance will degrade
* rapidly as 2^30^ is approached.
*
*/
@SerialVersionUID(1L)
final class AnyRefMap[K <: AnyRef, V] private[collection] (defaultEntry: K => V, initialBufferSize: Int, initBlank: Boolean)
extends AbstractMap[K, V]
with Map[K, V]
with MapLike[K, V, AnyRefMap[K, V]]
with Serializable
{
import AnyRefMap._
def this() = this(AnyRefMap.exceptionDefault, 16, true)
/** Creates a new `AnyRefMap` that returns default values according to a supplied key-value mapping. */
def this(defaultEntry: K => V) = this(defaultEntry, 16, true)
/** Creates a new `AnyRefMap` with an initial buffer of specified size.
*
* An `AnyRefMap` can typically contain half as many elements as its buffer size
* before it requires resizing.
*/
def this(initialBufferSize: Int) = this(AnyRefMap.exceptionDefault, initialBufferSize, true)
/** Creates a new `AnyRefMap` with specified default values and initial buffer size. */
def this(defaultEntry: K => V, initialBufferSize: Int) = this(defaultEntry, initialBufferSize, true)
private[this] var mask = 0
private[this] var _size = 0
private[this] var _vacant = 0
private[this] var _hashes: Array[Int] = null
private[this] var _keys: Array[AnyRef] = null
private[this] var _values: Array[AnyRef] = null
if (initBlank) defaultInitialize(initialBufferSize)
private[this] def defaultInitialize(n: Int) {
mask =
if (n<0) 0x7
else (((1 << (32 - java.lang.Integer.numberOfLeadingZeros(n-1))) - 1) & 0x3FFFFFFF) | 0x7
_hashes = new Array[Int](mask+1)
_keys = new Array[AnyRef](mask+1)
_values = new Array[AnyRef](mask+1)
}
private[collection] def initializeTo(
m: Int, sz: Int, vc: Int, hz: Array[Int], kz: Array[AnyRef], vz: Array[AnyRef]
) {
mask = m; _size = sz; _vacant = vc; _hashes = hz; _keys = kz; _values = vz
}
override def size: Int = _size
override def empty: AnyRefMap[K,V] = new AnyRefMap(defaultEntry)
private def imbalanced: Boolean =
(_size + _vacant) > 0.5*mask || _vacant > _size
private def hashOf(key: K): Int = {
// Note: this method must not return 0 or Int.MinValue, as these indicate no element
if (key eq null) 0x41081989
else {
val h = key.hashCode
// Part of the MurmurHash3 32 bit finalizer
val i = (h ^ (h >>> 16)) * 0x85EBCA6B
val j = (i ^ (i >>> 13)) & 0x7FFFFFFF
if (j==0) 0x41081989 else j
}
}
private def seekEntry(h: Int, k: AnyRef): Int = {
var e = h & mask
var x = 0
var g = 0
val hashes = _hashes
val keys = _keys
while ({ g = hashes(e); g != 0}) {
if (g == h && { val q = keys(e); (q eq k) || ((q ne null) && (q equals k)) }) return e
x += 1
e = (e + 2*(x+1)*x - 3) & mask
}
e | MissingBit
}
private def seekEntryOrOpen(h: Int, k: AnyRef): Int = {
var e = h & mask
var x = 0
var g = 0
var o = -1
while ({ g = _hashes(e); g != 0}) {
if (g == h && { val q = _keys(e); (q eq k) || ((q ne null) && (q equals k)) }) return e
else if (o == -1 && g+g == 0) o = e
x += 1
e = (e + 2*(x+1)*x - 3) & mask
}
if (o >= 0) o | MissVacant else e | MissingBit
}
override def contains(key: K): Boolean = seekEntry(hashOf(key), key) >= 0
override def get(key: K): Option[V] = {
val i = seekEntry(hashOf(key), key)
if (i < 0) None else Some(_values(i).asInstanceOf[V])
}
override def getOrElse[V1 >: V](key: K, default: => V1): V1 = {
val i = seekEntry(hashOf(key), key)
if (i < 0) default else _values(i).asInstanceOf[V]
}
override def getOrElseUpdate(key: K, defaultValue: => V): V = {
val h = hashOf(key)
var i = seekEntryOrOpen(h, key)
if (i < 0) {
// It is possible that the default value computation was side-effecting
// Our hash table may have resized or even contain what we want now
// (but if it does, we'll replace it)
val value = {
val oh = _hashes
val ans = defaultValue
if (oh ne _hashes) {
i = seekEntryOrOpen(h, key)
if (i >= 0) _size -= 1
}
ans
}
_size += 1
val j = i & IndexMask
_hashes(j) = h
_keys(j) = key.asInstanceOf[AnyRef]
_values(j) = value.asInstanceOf[AnyRef]
if ((i & VacantBit) != 0) _vacant -= 1
else if (imbalanced) repack()
value
}
else _values(i).asInstanceOf[V]
}
/** Retrieves the value associated with a key, or the default for that type if none exists
* (null for AnyRef, 0 for floats and integers).
*
* Note: this is the fastest way to retrieve a value that may or
* may not exist, if the default null/zero is acceptable. For key/value
* pairs that do exist, `apply` (i.e. `map(key)`) is equally fast.
*/
def getOrNull(key: K): V = {
val i = seekEntry(hashOf(key), key)
(if (i < 0) null else _values(i)).asInstanceOf[V]
}
/** Retrieves the value associated with a key.
* If the key does not exist in the map, the `defaultEntry` for that key
* will be returned instead; an exception will be thrown if no
* `defaultEntry` was supplied.
*/
override def apply(key: K): V = {
val i = seekEntry(hashOf(key), key)
if (i < 0) defaultEntry(key) else _values(i).asInstanceOf[V]
}
/** Defers to defaultEntry to find a default value for the key. Throws an
* exception if no other default behavior was specified.
*/
override def default(key: K) = defaultEntry(key)
private def repack(newMask: Int) {
val oh = _hashes
val ok = _keys
val ov = _values
mask = newMask
_hashes = new Array[Int](mask+1)
_keys = new Array[AnyRef](mask+1)
_values = new Array[AnyRef](mask+1)
_vacant = 0
var i = 0
while (i < oh.length) {
val h = oh(i)
if (h+h != 0) {
var e = h & mask
var x = 0
while (_hashes(e) != 0) { x += 1; e = (e + 2*(x+1)*x - 3) & mask }
_hashes(e) = h
_keys(e) = ok(i)
_values(e) = ov(i)
}
i += 1
}
}
/** Repacks the contents of this `AnyRefMap` for maximum efficiency of lookup.
*
* For maps that undergo a complex creation process with both addition and
* removal of keys, and then are used heavily with no further removal of
* elements, calling `repack` after the end of the creation can result in
* improved performance. Repacking takes time proportional to the number
* of entries in the map.
*/
def repack() {
var m = mask
if (_size + _vacant >= 0.5*mask && !(_vacant > 0.2*mask)) m = ((m << 1) + 1) & IndexMask
while (m > 8 && 8*_size < m) m = m >>> 1
repack(m)
}
override def put(key: K, value: V): Option[V] = {
val h = hashOf(key)
val k = key
val i = seekEntryOrOpen(h, k)
if (i < 0) {
val j = i & IndexMask
_hashes(j) = h
_keys(j) = k
_values(j) = value.asInstanceOf[AnyRef]
_size += 1
if ((i & VacantBit) != 0) _vacant -= 1
else if (imbalanced) repack()
None
}
else {
val ans = Some(_values(i).asInstanceOf[V])
_hashes(i) = h
_keys(i) = k
_values(i) = value.asInstanceOf[AnyRef]
ans
}
}
/** Updates the map to include a new key-value pair.
*
* This is the fastest way to add an entry to an `AnyRefMap`.
*/
override def update(key: K, value: V): Unit = {
val h = hashOf(key)
val k = key
val i = seekEntryOrOpen(h, k)
if (i < 0) {
val j = i & IndexMask
_hashes(j) = h
_keys(j) = k
_values(j) = value.asInstanceOf[AnyRef]
_size += 1
if ((i & VacantBit) != 0) _vacant -= 1
else if (imbalanced) repack()
}
else {
_hashes(i) = h
_keys(i) = k
_values(i) = value.asInstanceOf[AnyRef]
}
}
/** Adds a new key/value pair to this map and returns the map. */
def +=(key: K, value: V): this.type = { update(key, value); this }
def +=(kv: (K, V)): this.type = { update(kv._1, kv._2); this }
def -=(key: K): this.type = {
val i = seekEntry(hashOf(key), key)
if (i >= 0) {
_size -= 1
_vacant += 1
_hashes(i) = Int.MinValue
_keys(i) = null
_values(i) = null
}
this
}
def iterator: Iterator[(K, V)] = new Iterator[(K, V)] {
private[this] val hz = _hashes
private[this] val kz = _keys
private[this] val vz = _values
private[this] var index = 0
def hasNext: Boolean = index= hz.length) return false
h = hz(index)
}
true
}
def next: (K, V) = {
if (hasNext) {
val ans = (kz(index).asInstanceOf[K], vz(index).asInstanceOf[V])
index += 1
ans
}
else throw new NoSuchElementException("next")
}
}
override def foreach[U](f: ((K,V)) => U) {
var i = 0
var e = _size
while (e > 0) {
while(i < _hashes.length && { val h = _hashes(i); h+h == 0 && i < _hashes.length}) i += 1
if (i < _hashes.length) {
f((_keys(i).asInstanceOf[K], _values(i).asInstanceOf[V]))
i += 1
e -= 1
}
else return
}
}
override def clone(): AnyRefMap[K, V] = {
val hz = java.util.Arrays.copyOf(_hashes, _hashes.length)
val kz = java.util.Arrays.copyOf(_keys, _keys.length)
val vz = java.util.Arrays.copyOf(_values, _values.length)
val arm = new AnyRefMap[K, V](defaultEntry, 1, false)
arm.initializeTo(mask, _size, _vacant, hz, kz, vz)
arm
}
override def +[V1 >: V](kv: (K, V1)): AnyRefMap[K, V1] = {
val arm = clone().asInstanceOf[AnyRefMap[K, V1]]
arm += kv
arm
}
override def ++[V1 >: V](xs: GenTraversableOnce[(K, V1)]): AnyRefMap[K, V1] = {
val arm = clone().asInstanceOf[AnyRefMap[K, V1]]
xs.foreach(kv => arm += kv)
arm
}
override def updated[V1 >: V](key: K, value: V1): AnyRefMap[K, V1] = {
val arm = clone().asInstanceOf[AnyRefMap[K, V1]]
arm += (key, value)
arm
}
private[this] def foreachElement[A,B](elems: Array[AnyRef], f: A => B) {
var i,j = 0
while (i < _hashes.length & j < _size) {
val h = _hashes(i)
if (h+h != 0) {
j += 1
f(elems(i).asInstanceOf[A])
}
i += 1
}
}
/** Applies a function to all keys of this map. */
def foreachKey[A](f: K => A) { foreachElement[K,A](_keys, f) }
/** Applies a function to all values of this map. */
def foreachValue[A](f: V => A) { foreachElement[V,A](_values, f) }
/** Creates a new `AnyRefMap` with different values.
* Unlike `mapValues`, this method generates a new
* collection immediately.
*/
def mapValuesNow[V1](f: V => V1): AnyRefMap[K, V1] = {
val arm = new AnyRefMap[K,V1](AnyRefMap.exceptionDefault, 1, false)
val hz = java.util.Arrays.copyOf(_hashes, _hashes.length)
val kz = java.util.Arrays.copyOf(_keys, _keys.length)
val vz = new Array[AnyRef](_values.length)
var i,j = 0
while (i < _hashes.length & j < _size) {
val h = _hashes(i)
if (h+h != 0) {
j += 1
vz(i) = f(_values(i).asInstanceOf[V]).asInstanceOf[AnyRef]
}
i += 1
}
arm.initializeTo(mask, _size, _vacant, hz, kz, vz)
arm
}
/** Applies a transformation function to all values stored in this map.
* Note: the default, if any, is not transformed.
*/
def transformValues(f: V => V): this.type = {
var i,j = 0
while (i < _hashes.length & j < _size) {
val h = _hashes(i)
if (h+h != 0) {
j += 1
_values(i) = f(_values(i).asInstanceOf[V]).asInstanceOf[AnyRef]
}
i += 1
}
this
}
override def clear(): Unit = {
import java.util.Arrays.fill
fill(_keys, null)
fill(_values, null)
fill(_hashes, 0)
_size = 0
_vacant = 0
}
}
object AnyRefMap {
private final val IndexMask = 0x3FFFFFFF
private final val MissingBit = 0x80000000
private final val VacantBit = 0x40000000
private final val MissVacant = 0xC0000000
@SerialVersionUID(1L)
private class ExceptionDefault extends (Any => Nothing) with Serializable {
def apply(k: Any): Nothing = throw new NoSuchElementException(if (k == null) "(null)" else k.toString)
}
private val exceptionDefault = new ExceptionDefault
implicit def canBuildFrom[K <: AnyRef, V, J <: AnyRef, U]: CanBuildFrom[AnyRefMap[K,V], (J, U), AnyRefMap[J,U]] =
ReusableCBFInstance.asInstanceOf[CanBuildFrom[AnyRefMap[K, V], (J, U), AnyRefMap[J, U]]]
private[this] val ReusableCBFInstance = new CanBuildFrom[AnyRefMap[AnyRef, Any], (AnyRef, Any), AnyRefMap[AnyRef, Any]] {
def apply(from: AnyRefMap[AnyRef, Any]): AnyRefMapBuilder[AnyRef, Any] = apply()
def apply(): AnyRefMapBuilder[AnyRef, Any] = new AnyRefMapBuilder[AnyRef, Any]
}
/** A builder for instances of `AnyRefMap`.
*
* This builder can be reused to create multiple instances.
*/
final class AnyRefMapBuilder[K <: AnyRef, V] extends ReusableBuilder[(K, V), AnyRefMap[K, V]] {
private[collection] var elems: AnyRefMap[K, V] = new AnyRefMap[K, V]
def +=(entry: (K, V)): this.type = {
elems += entry
this
}
def clear() { elems = new AnyRefMap[K, V] }
def result(): AnyRefMap[K, V] = elems
}
/** Creates a new `AnyRefMap` with zero or more key/value pairs. */
def apply[K <: AnyRef, V](elems: (K, V)*): AnyRefMap[K, V] = {
val sz = if (elems.hasDefiniteSize) elems.size else 4
val arm = new AnyRefMap[K, V](sz * 2)
elems.foreach{ case (k,v) => arm(k) = v }
if (arm.size < (sz>>3)) arm.repack()
arm
}
/** Creates a new empty `AnyRefMap`. */
def empty[K <: AnyRef, V]: AnyRefMap[K, V] = new AnyRefMap[K, V]
/** Creates a new empty `AnyRefMap` with the supplied default */
def withDefault[K <: AnyRef, V](default: K => V): AnyRefMap[K, V] = new AnyRefMap[K, V](default)
/** Creates a new `AnyRefMap` from arrays of keys and values.
* Equivalent to but more efficient than `AnyRefMap((keys zip values): _*)`.
*/
def fromZip[K <: AnyRef, V](keys: Array[K], values: Array[V]): AnyRefMap[K, V] = {
val sz = math.min(keys.length, values.length)
val arm = new AnyRefMap[K, V](sz * 2)
var i = 0
while (i < sz) { arm(keys(i)) = values(i); i += 1 }
if (arm.size < (sz>>3)) arm.repack()
arm
}
/** Creates a new `AnyRefMap` from keys and values.
* Equivalent to but more efficient than `AnyRefMap((keys zip values): _*)`.
*/
def fromZip[K <: AnyRef, V](keys: Iterable[K], values: Iterable[V]): AnyRefMap[K, V] = {
val sz = math.min(keys.size, values.size)
val arm = new AnyRefMap[K, V](sz * 2)
val ki = keys.iterator
val vi = values.iterator
while (ki.hasNext && vi.hasNext) arm(ki.next) = vi.next
if (arm.size < (sz >> 3)) arm.repack()
arm
}
}
