/* __ *\ ** ________ ___ / / ___ Scala API ** ** / __/ __// _ | / / / _ | (c) 2003-2013, LAMP/EPFL ** ** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** ** /____/\___/_/ |_/____/_/ | | ** ** |/ ** \* */ package scala package collection package immutable import generic._ import scala.annotation.unchecked.{ uncheckedVariance=> uV } import parallel.immutable.ParHashMap /** This class implements immutable maps using a hash trie. * * '''Note:''' The builder of this hash map may return specialized representations for small maps. * * @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) sealed 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]] { import HashMap.{nullToEmpty, bufferSize} 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 final def contains(key: A): Boolean = contains0(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 def - (key: A): HashMap[A, B] = removed0(key, computeHash(key), 0) override def tail: HashMap[A, B] = this - head._1 override def filter(p: ((A, B)) => Boolean) = { val buffer = new Array[HashMap[A, B]](bufferSize(size)) nullToEmpty(filter0(p, false, 0, buffer, 0)) } override def filterNot(p: ((A, B)) => Boolean) = { val buffer = new Array[HashMap[A, B]](bufferSize(size)) nullToEmpty(filter0(p, true, 0, buffer, 0)) } protected def filter0(p: ((A, B)) => Boolean, negate: Boolean, level: Int, buffer: Array[HashMap[A, B @uV]], offset0: Int): HashMap[A, B] = null 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)) import HashMap.{Merger, MergeFunction, liftMerger} private[collection] def get0(key: A, hash: Int, level: Int): Option[B] = None protected def contains0(key: A, hash: Int, level: Int): Boolean = false 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) /** 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[collection] abstract class Merger[A, B] { def apply(kv1: (A, B), kv2: (A, B)): (A, B) def invert: Merger[A, B] } private type MergeFunction[A1, B1] = ((A1, B1), (A1, B1)) => (A1, B1) private def liftMerger[A1, B1](mergef: MergeFunction[A1, B1]): Merger[A1, B1] = if (mergef == null) defaultMerger.asInstanceOf[Merger[A1, B1]] else liftMerger0(mergef) private[this] val defaultMerger : Merger[Any, Any] = liftMerger0((a,b) => a) private[this] def liftMerger0[A1, B1](mergef: MergeFunction[A1, B1]): Merger[A1, B1] = 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 } } /** $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] { override def head: (Any, Nothing) = throw new NoSuchElementException("Empty Map") override def tail: HashMap[Any, Nothing] = throw new NoSuchElementException("Empty Map") } // utility method to create a HashTrieMap from two leaf HashMaps (HashMap1 or HashMapCollision1) with non-colliding hash code) private def makeHashTrieMap[A, B](hash0:Int, elem0:HashMap[A, B], hash1:Int, elem1:HashMap[A, B], level:Int, size:Int) : HashTrieMap[A, B] = { val index0 = (hash0 >>> level) & 0x1f val index1 = (hash1 >>> level) & 0x1f if(index0 != index1) { val bitmap = (1 << index0) | (1 << index1) val elems = new Array[HashMap[A,B]](2) if(index0 < index1) { elems(0) = elem0 elems(1) = elem1 } else { elems(0) = elem1 elems(1) = elem0 } new HashTrieMap[A, B](bitmap, elems, size) } else { val elems = new Array[HashMap[A,B]](1) val bitmap = (1 << index0) elems(0) = makeHashTrieMap(hash0, elem0, hash1, elem1, level + 5, size) new HashTrieMap[A, B](bitmap, elems, size) } } @deprecatedInheritance("This class will be made final in a future release.", "2.12.2") 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 protected def contains0(key: A, hash: Int, level: Int): Boolean = hash == this.hash && key == this.key private[collection] 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.ensurePair, if(kv != null) kv else (key, value)) new HashMap1(nkv._1, hash, nkv._2, nkv) } } else { if (hash != this.hash) { // they have different hashes, but may collide at this level - find a level at which they don't val that = new HashMap1[A, B1](key, hash, value, kv) makeHashTrieMap[A,B1](this.hash, this, hash, that, level, 2) } 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 protected def filter0(p: ((A, B)) => Boolean, negate: Boolean, level: Int, buffer: Array[HashMap[A, B @uV]], offset0: Int): HashMap[A, B] = if (negate ^ p(ensurePair)) this else null 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, merger.invert) } } private[collection] class HashMapCollision1[A, +B](private[collection] val hash: Int, val kvs: ListMap[A, B @uV]) extends HashMap[A, B @uV] { // assert(kvs.size > 1) 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 protected def contains0(key: A, hash: Int, level: Int): Boolean = hash == this.hash && kvs.contains(key) private[collection] 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 { val that = new HashMap1(key, hash, value, kv) makeHashTrieMap(this.hash, this, hash, that, level, size + 1) } override def removed0(key: A, hash: Int, level: Int): HashMap[A, B] = if (hash == this.hash) { val kvs1 = kvs - key kvs1.size match { case 0 => HashMap.empty[A,B] case 1 => val kv = kvs1.head new HashMap1(kv._1,hash,kv._2,kv) case x if x == kvs.size => this case _ => new HashMapCollision1(hash, kvs1) } } else this override protected def filter0(p: ((A, B)) => Boolean, negate: Boolean, level: Int, buffer: Array[HashMap[A, B @uV]], offset0: Int): HashMap[A, B] = { val kvs1 = if(negate) kvs.filterNot(p) else kvs.filter(p) kvs1.size match { case 0 => null case 1 => val kv@(k,v) = kvs1.head new HashMap1(k, hash, v, kv) case x if x == kvs.size => this case _ => new HashMapCollision1(hash, kvs1) } } 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 } } @deprecatedInheritance("This class will be made final in a future release.", "2.12.2") 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] { // assert(Integer.bitCount(bitmap) == elems.length) // assert(elems.length > 1 || (elems.length == 1 && elems(0).isInstanceOf[HashTrieMap[_,_]])) override def size = size0 override def get0(key: A, hash: Int, level: Int): Option[B] = { // Note: this code is duplicated with `contains0` val index = (hash >>> level) & 0x1f if (bitmap == - 1) { elems(index).get0(key, hash, level + 5) } else { val mask = (1 << index) if ((bitmap & mask) != 0) { val offset = Integer.bitCount(bitmap & (mask - 1)) elems(offset).get0(key, hash, level + 5) } else { None } } } override protected def contains0(key: A, hash: Int, level: Int): Boolean = { // Note: this code is duplicated from `get0` val index = (hash >>> level) & 0x1f if (bitmap == - 1) { elems(index).contains0(key, hash, level + 5) } else { val mask = (1 << index) if ((bitmap & mask) != 0) { val offset = Integer.bitCount(bitmap & (mask - 1)) elems(offset).contains0(key, hash, level + 5) } else { false } } } private[collection] 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) 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) 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 // 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[HashTrieMap[_,_]]) elemsNew(0) else new HashTrieMap(bitmapNew, elemsNew, sizeNew) } else HashMap.empty[A,B] } else if(elems.length == 1 && !subNew.isInstanceOf[HashTrieMap[_,_]]) { subNew } 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 protected def filter0(p: ((A, B)) => Boolean, negate: Boolean, level: Int, buffer: Array[HashMap[A, B @uV]], offset0: Int): HashMap[A, B] = { // current offset var offset = offset0 // result size var rs = 0 // bitmap for kept elems var kept = 0 // loop over all elements var i = 0 while (i < elems.length) { val result = elems(i).filter0(p, negate, level + 5, buffer, offset) if (result ne null) { buffer(offset) = result offset += 1 // add the result size rs += result.size // mark the bit i as kept kept |= (1 << i) } i += 1 } if (offset == offset0) { // empty null } else if (rs == size0) { // unchanged this } else if (offset == offset0 + 1 && !buffer(offset0).isInstanceOf[HashTrieMap[A, B]]) { // leaf buffer(offset0) } else { // we have to return a HashTrieMap val length = offset - offset0 val elems1 = new Array[HashMap[A, B]](length) System.arraycopy(buffer, offset0, elems1, 0, length) val bitmap1 = if (length == elems.length) { // we can reuse the original bitmap bitmap } else { // calculate new bitmap by keeping just bits in the kept bitmask keepBits(bitmap, kept) } new HashTrieMap(bitmap1, elems1, rs) } } 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 } 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 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, merger.invert) case hm: HashMap[_, _] => this case _ => sys.error("section supposed to be unreachable.") } } /** * Calculates the maximum buffer size given the maximum possible total size of the trie-based collection * @param size the maximum size of the collection to be generated * @return the maximum buffer size */ @inline private def bufferSize(size: Int): Int = (size + 6) min (32 * 7) /** * In many internal operations the empty map is represented as null for performance reasons. This method converts * null to the empty map for use in public methods */ @inline private def nullToEmpty[A, B](m: HashMap[A, B]): HashMap[A, B] = if (m eq null) empty[A, B] else m /** * Utility method to keep a subset of all bits in a given bitmap * * Example * bitmap (binary): 00000001000000010000000100000001 * keep (binary): 1010 * result (binary): 00000001000000000000000100000000 * * @param bitmap the bitmap * @param keep a bitmask containing which bits to keep * @return the original bitmap with all bits where keep is not 1 set to 0 */ private def keepBits(bitmap: Int, keep: Int): Int = { var result = 0 var current = bitmap var kept = keep while (kept != 0) { // lowest remaining bit in current val lsb = current ^ (current & (current - 1)) if ((kept & 1) != 0) { // mark bit in result bitmap result |= lsb } // clear lowest remaining one bit in abm current &= ~lsb // look at the next kept bit kept >>>= 1 } result } @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 } }