1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
|
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2011, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala.collection
package immutable
import generic._
import annotation.unchecked.{ uncheckedVariance=> uV }
import parallel.immutable.ParHashMap
/** This class implements immutable maps using a hash trie.
*
* '''Note:''' the builder of a hash map returns specialized representations EmptyMap,Map1,..., Map4
* for maps of size <= 4.
*
* @tparam A the type of the keys contained in this hash map.
* @tparam B the type of the values associated with the keys.
*
* @author Martin Odersky
* @author Tiark Rompf
* @version 2.8
* @since 2.3
* @see [[http://docs.scala-lang.org/overviews/collections/concrete-immutable-collection-classes.html#hash_tries "Scala's Collection Library overview"]]
* section on `Hash Tries` for more information.
* @define Coll `immutable.HashMap`
* @define coll immutable hash map
* @define mayNotTerminateInf
* @define willNotTerminateInf
*/
@SerialVersionUID(2L)
class HashMap[A, +B] extends AbstractMap[A, B]
with Map[A, B]
with MapLike[A, B, HashMap[A, B]]
with Serializable
with CustomParallelizable[(A, B), ParHashMap[A, B]]
{
override def size: Int = 0
override def empty = HashMap.empty[A, B]
def iterator: Iterator[(A,B)] = Iterator.empty
override def foreach[U](f: ((A, B)) => U): Unit = { }
def get(key: A): Option[B] =
get0(key, computeHash(key), 0)
override def updated [B1 >: B] (key: A, value: B1): HashMap[A, B1] =
updated0(key, computeHash(key), 0, value, null, null)
override def + [B1 >: B] (kv: (A, B1)): HashMap[A, B1] =
updated0(kv._1, computeHash(kv._1), 0, kv._2, kv, null)
override def + [B1 >: B] (elem1: (A, B1), elem2: (A, B1), elems: (A, B1) *): HashMap[A, B1] =
this + elem1 + elem2 ++ elems
// TODO: optimize (might be able to use mutable updates)
def - (key: A): HashMap[A, B] =
removed0(key, computeHash(key), 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 type MergeFunction[A1, B1] = ((A1, B1), (A1, B1)) => (A1, B1);
import HashMap.Merger
protected def liftMerger[A1, B1](mergef: MergeFunction[A1, B1]): Merger[A1, B1] = if (mergef == null) null else new Merger[A1, B1] {
self =>
def apply(kv1: (A1, B1), kv2: (A1, B1)): (A1, B1) = mergef(kv1, kv2)
val invert: Merger[A1, B1] = new Merger[A1, B1] {
def apply(kv1: (A1, B1), kv2: (A1, B1)): (A1, B1) = mergef(kv2, kv1)
def invert: Merger[A1, B1] = self
}
}
private[collection] def get0(key: A, hash: Int, level: Int): Option[B] = None
private[collection] def updated0[B1 >: B](key: A, hash: Int, level: Int, value: B1, kv: (A, B1), merger: Merger[A, B1]): HashMap[A, B1] =
new HashMap.HashMap1(key, hash, value, kv)
protected def removed0(key: A, hash: Int, level: Int): HashMap[A, B] = this
protected def writeReplace(): AnyRef = new HashMap.SerializationProxy(this)
def split: Seq[HashMap[A, B]] = Seq(this)
@deprecated("Use the `merged` method instead.", "2.10.0")
def merge[B1 >: B](that: HashMap[A, B1], mergef: MergeFunction[A, B1] = null): HashMap[A, B1] = merge0(that, 0, liftMerger(mergef))
/** Creates a new map which is the merge of this and the argument hash map.
*
* Uses the specified collision resolution function if two keys are the same.
* The collision resolution function will always take the first argument from
* `this` hash map and the second from `that`.
*
* The `merged` method is on average more performant than doing a traversal and reconstructing a
* new immutable hash map from scratch, or `++`.
*
* @tparam B1 the value type of the other hash map
* @param that the other hash map
* @param mergef the merge function or null if the first key-value pair is to be picked
*/
def merged[B1 >: B](that: HashMap[A, B1])(mergef: MergeFunction[A, B1]): HashMap[A, B1] = merge0(that, 0, liftMerger(mergef))
protected def merge0[B1 >: B](that: HashMap[A, B1], level: Int, merger: Merger[A, B1]): HashMap[A, B1] = that
override def par = ParHashMap.fromTrie(this)
}
/** $factoryInfo
* @define Coll `immutable.HashMap`
* @define coll immutable hash map
*
* @author Tiark Rompf
* @since 2.3
*/
object HashMap extends ImmutableMapFactory[HashMap] with BitOperations.Int {
private[immutable] abstract class Merger[A, B] {
def apply(kv1: (A, B), kv2: (A, B)): (A, B)
def invert: Merger[A, B]
}
/** $mapCanBuildFromInfo */
implicit def canBuildFrom[A, B]: CanBuildFrom[Coll, (A, B), HashMap[A, B]] = new MapCanBuildFrom[A, B]
def empty[A, B]: HashMap[A, B] = EmptyHashMap.asInstanceOf[HashMap[A, B]]
private object EmptyHashMap extends HashMap[Any, Nothing] { }
// TODO: add HashMap2, HashMap3, ...
class HashMap1[A,+B](private[collection] val key: A, private[collection] val hash: Int, private[collection] val value: (B @uV), private[collection] var kv: (A,B @uV)) extends HashMap[A,B] {
override def size = 1
private[collection] def getKey = key
private[collection] def getHash = hash
private[collection] def computeHashFor(k: A) = computeHash(k)
override def get0(key: A, hash: Int, level: Int): Option[B] =
if (hash == this.hash && key == this.key) Some(value) else None
// override def updated0[B1 >: B](key: A, hash: Int, level: Int, value: B1, kv: (A, B1)): HashMap[A, B1] =
// if (hash == this.hash && key == this.key) new HashMap1(key, hash, value, kv)
// else {
// var thatindex = (hash >>> level) & 0x1f
// var thisindex = (this.hash >>> level) & 0x1f
// if (hash != this.hash) {
// --new HashTrieMap[A,B1](level+5, this, new HashMap1(key, hash, value, kv))
// val m = new HashTrieMap[A,B1](0,new Array[HashMap[A,B1]](0),0) // TODO: could save array alloc
// m.updated0(this.key, this.hash, level, this.value, this.kv).updated0(key, hash, level, value, kv) TODO and it will
// } else {
// 32-bit hash collision (rare, but not impossible)
// new HashMapCollision1(hash, ListMap.empty.updated(this.key,this.value).updated(key,value))
// }
// }
override def updated0[B1 >: B](key: A, hash: Int, level: Int, value: B1, kv: (A, B1), merger: Merger[A, B1]): HashMap[A, B1] =
if (hash == this.hash && key == this.key ) {
if (merger eq null) {
if (this.value.asInstanceOf[AnyRef] eq value.asInstanceOf[AnyRef]) this
else new HashMap1(key, hash, value, kv)
} else {
val nkv = merger(this.kv, kv)
new HashMap1(nkv._1, hash, nkv._2, nkv)
}
} else {
var thatindex = (hash >>> level) & 0x1f
var thisindex = (this.hash >>> level) & 0x1f
if (hash != this.hash) {
// they have different hashes, but may collide at this level - find a level at which they don't
var lvl = level
var top: HashTrieMap[A, B1] = null
var prev: HashTrieMap[A, B1] = null
while (thisindex == thatindex) {
val newlevel = new HashTrieMap[A, B1](1 << thisindex, new Array[HashMap[A, B1]](1), 2)
if (prev ne null) prev.elems(0) = newlevel else top = newlevel
prev = newlevel
lvl += 5
thatindex = (hash >>> lvl) & 0x1f
thisindex = (this.hash >>> lvl) & 0x1f
}
val bottelems = new Array[HashMap[A,B1]](2)
val ind = if (thisindex < thatindex) 1 else 0
bottelems(1 - ind) = this
bottelems(ind) = new HashMap1[A, B1](key, hash, value, kv)
val bottom = new HashTrieMap[A,B1]((1 << thisindex) | (1 << thatindex), bottelems, 2)
if (prev ne null) {
prev.elems(0) = bottom
top
} else bottom
} else {
// 32-bit hash collision (rare, but not impossible)
new HashMapCollision1(hash, ListMap.empty.updated(this.key,this.value).updated(key,value))
}
}
override def removed0(key: A, hash: Int, level: Int): HashMap[A, B] =
if (hash == this.hash && key == this.key) HashMap.empty[A,B] else this
override def iterator: Iterator[(A,B)] = Iterator(ensurePair)
override def foreach[U](f: ((A, B)) => U): Unit = f(ensurePair)
// this method may be called multiple times in a multithreaded environment, but that's ok
private[HashMap] def ensurePair: (A,B) = if (kv ne null) kv else { kv = (key, value); kv }
protected override def merge0[B1 >: B](that: HashMap[A, B1], level: Int, merger: Merger[A, B1]): HashMap[A, B1] = {
that.updated0(key, hash, level, value, kv, if (merger ne null) merger.invert else null)
}
}
private[collection] class HashMapCollision1[A, +B](private[collection] val hash: Int, val kvs: ListMap[A, B @uV])
extends HashMap[A, B @uV] {
override def size = kvs.size
override def get0(key: A, hash: Int, level: Int): Option[B] =
if (hash == this.hash) kvs.get(key) else None
override def updated0[B1 >: B](key: A, hash: Int, level: Int, value: B1, kv: (A, B1), merger: Merger[A, B1]): HashMap[A, B1] =
if (hash == this.hash) {
if ((merger eq null) || !kvs.contains(key)) new HashMapCollision1(hash, kvs.updated(key, value))
else new HashMapCollision1(hash, kvs + merger((key, kvs(key)), kv))
} else {
var m: HashMap[A,B1] = new HashTrieMap[A,B1](0,new Array[HashMap[A,B1]](0),0)
// might be able to save some ops here, but it doesn't seem to be worth it
for ((k,v) <- kvs)
m = m.updated0(k, this.hash, level, v, null, merger)
m.updated0(key, hash, level, value, kv, merger)
}
override def removed0(key: A, hash: Int, level: Int): HashMap[A, B] =
if (hash == this.hash) {
val kvs1 = kvs - key
if (!kvs1.isEmpty)
new HashMapCollision1(hash, kvs1)
else
HashMap.empty[A,B]
} else this
override def iterator: Iterator[(A,B)] = kvs.iterator
override def foreach[U](f: ((A, B)) => U): Unit = kvs.foreach(f)
override def split: Seq[HashMap[A, B]] = {
val (x, y) = kvs.splitAt(kvs.size / 2)
def newhm(lm: ListMap[A, B @uV]) = new HashMapCollision1(hash, lm)
List(newhm(x), newhm(y))
}
protected override def merge0[B1 >: B](that: HashMap[A, B1], level: Int, merger: Merger[A, B1]): HashMap[A, B1] = {
// this can be made more efficient by passing the entire ListMap at once
var m = that
for (p <- kvs) m = m.updated0(p._1, this.hash, level, p._2, p, merger)
m
}
}
class HashTrieMap[A, +B](
private[collection] val bitmap: Int,
private[collection] val elems: Array[HashMap[A, B @uV]],
private[collection] val size0: Int
) extends HashMap[A, B @uV] {
/*
def this (level: Int, m1: HashMap1[A,B], m2: HashMap1[A,B]) = {
this(((m1.hash >>> level) & 0x1f) | ((m2.hash >>> level) & 0x1f), {
val idx1 = (m1.hash >>> level) & 0x1f
val idx2 = (m2.hash >>> level) & 0x1f
assert(idx1 != idx2, m1.hash + "==" + m2.hash + " at level " + level) // TODO
val elems = new Array[HashMap[A,B]](2)
if (idx1 < idx2) {
elems(0) = m1
elems(1) = m2
} else {
elems(0) = m2
elems(1) = m1
}
elems
}, 2)
}
*/
override def size = size0
override def get0(key: A, hash: Int, level: Int): Option[B] = {
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 HashTrieMap (-> monomorphic call site)
elems(offset).get0(key, hash, level + 5)
} else
None
}
override def updated0[B1 >: B](key: A, hash: Int, level: Int, value: B1, kv: (A, B1), merger: Merger[A, B1]): HashMap[A, B1] = {
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.updated0(key, hash, level + 5, value, kv, merger)
if(subNew eq sub) this else {
val elemsNew = new Array[HashMap[A,B1]](elems.length)
Array.copy(elems, 0, elemsNew, 0, elems.length)
elemsNew(offset) = subNew
new HashTrieMap(bitmap, elemsNew, size + (subNew.size - sub.size))
}
} else {
val elemsNew = new Array[HashMap[A,B1]](elems.length + 1)
Array.copy(elems, 0, elemsNew, 0, offset)
elemsNew(offset) = new HashMap1(key, hash, value, kv)
Array.copy(elems, offset, elemsNew, offset + 1, elems.length - offset)
new HashTrieMap(bitmap | mask, elemsNew, size + 1)
}
}
override def removed0(key: A, hash: Int, level: Int): HashMap[A, B] = {
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 (subNew eq sub) this
else if (subNew.isEmpty) {
val bitmapNew = bitmap ^ mask
if (bitmapNew != 0) {
val elemsNew = new Array[HashMap[A,B]](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
new HashTrieMap(bitmapNew, elemsNew, sizeNew)
} else
HashMap.empty[A,B]
} else {
val elemsNew = new Array[HashMap[A,B]](elems.length)
Array.copy(elems, 0, elemsNew, 0, elems.length)
elemsNew(offset) = subNew
val sizeNew = size + (subNew.size - sub.size)
new HashTrieMap(bitmap, elemsNew, sizeNew)
}
} else {
this
}
}
override def iterator: Iterator[(A, B)] = new TrieIterator[(A, B)](elems.asInstanceOf[Array[Iterable[(A, B)]]]) {
final override def getElem(cc: AnyRef): (A, B) = cc.asInstanceOf[HashMap1[A, B]].ensurePair
}
/*
def time(block: =>Unit) = { val t0 = System.nanoTime; block; println("elapsed: " + (System.nanoTime - t0)/1000000.0) }
var mOld = OldHashMap.empty[Int,Int]
var mNew = HashMap.empty[Int,Int]
time { for (i <- 0 until 100000) mOld = mOld.updated(i,i) }
time { for (i <- 0 until 100000) mOld = mOld.updated(i,i) }
time { for (i <- 0 until 100000) mOld = mOld.updated(i,i) }
time { for (i <- 0 until 100000) mNew = mNew.updated(i,i) }
time { for (i <- 0 until 100000) mNew = mNew.updated(i,i) }
time { for (i <- 0 until 100000) mNew = mNew.updated(i,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, B)) => U): Unit = {
var i = 0;
while (i < elems.length) {
elems(i).foreach(f)
i += 1
}
}
private def posOf(n: Int, bm: Int) = {
var left = n
var i = -1
var b = bm
while (left >= 0) {
i += 1
if ((b & 1) != 0) left -= 1
b = b >>> 1
}
i
}
override def split: Seq[HashMap[A, B]] = if (size == 1) Seq(this) else {
val nodesize = Integer.bitCount(bitmap)
if (nodesize > 1) {
val splitpoint = nodesize / 2
val bitsplitpoint = posOf(nodesize / 2, bitmap)
val bm1 = bitmap & (-1 << bitsplitpoint)
val bm2 = bitmap & (-1 >>> (32 - bitsplitpoint))
val (e1, e2) = elems.splitAt(splitpoint)
val hm1 = new HashTrieMap(bm1, e1, e1.foldLeft(0)(_ + _.size))
val hm2 = new HashTrieMap(bm2, e2, e2.foldLeft(0)(_ + _.size))
List(hm1, hm2)
} else elems(0).split
}
protected override def merge0[B1 >: B](that: HashMap[A, B1], level: Int, merger: Merger[A, B1]): HashMap[A, B1] = that match {
case hm: HashMap1[_, _] =>
this.updated0(hm.key, hm.hash, level, hm.value.asInstanceOf[B1], hm.kv, merger)
case hm: HashTrieMap[_, _] =>
val that = hm.asInstanceOf[HashTrieMap[A, B1]]
val thiselems = this.elems
val thatelems = that.elems
var thisbm = this.bitmap
var thatbm = that.bitmap
// determine the necessary size for the array
val subcount = Integer.bitCount(thisbm | thatbm)
// construct a new array of appropriate size
val merged = new Array[HashMap[A, B1]](subcount)
// run through both bitmaps and add elements to it
var i = 0
var thisi = 0
var thati = 0
var totalelems = 0
while (i < subcount) {
val thislsb = thisbm ^ (thisbm & (thisbm - 1))
val thatlsb = thatbm ^ (thatbm & (thatbm - 1))
// collision
if (thislsb == thatlsb) {
val m = thiselems(thisi).merge0(thatelems(thati), level + 5, merger)
totalelems += m.size
merged(i) = m
thisbm = thisbm & ~thislsb
thatbm = thatbm & ~thatlsb
thati += 1
thisi += 1
} else {
// condition below is due to 2 things:
// 1) no unsigned int compare on JVM
// 2) 0 (no lsb) should always be greater in comparison
val a = thislsb - 1
val b = thatlsb - 1
if (unsignedCompare(thislsb - 1, thatlsb - 1)) {
val m = thiselems(thisi)
totalelems += m.size
merged(i) = m
thisbm = thisbm & ~thislsb
thisi += 1
}
else {
val m = thatelems(thati)
totalelems += m.size
merged(i) = m
thatbm = thatbm & ~thatlsb
thati += 1
}
}
i += 1
}
new HashTrieMap[A, B1](this.bitmap | that.bitmap, merged, totalelems)
case hm: HashMapCollision1[_, _] => that.merge0(this, level, if (merger ne null) merger.invert else null)
case hm: HashMap[_, _] => this
case _ => sys.error("section supposed to be unreachable.")
}
}
@SerialVersionUID(2L)
private class SerializationProxy[A,B](@transient private var orig: HashMap[A, B]) extends Serializable {
private def writeObject(out: java.io.ObjectOutputStream) {
val s = orig.size
out.writeInt(s)
for ((k,v) <- orig) {
out.writeObject(k)
out.writeObject(v)
}
}
private def readObject(in: java.io.ObjectInputStream) {
orig = empty
val s = in.readInt()
for (i <- 0 until s) {
val key = in.readObject().asInstanceOf[A]
val value = in.readObject().asInstanceOf[B]
orig = orig.updated(key, value)
}
}
private def readResolve(): AnyRef = orig
}
}
|