Scala example source code file (ParMapLike.scala)

This example Scala source code file (ParMapLike.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

annotation, collection, generics, iterablesplitter, k, mutable, none, parmap, parset, repr, s, sequential, u, v

The ParMapLike.scala Scala example source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

package scala
package collection.parallel

import scala.collection.MapLike
import scala.collection.GenMapLike
import scala.collection.Map
import scala.collection.mutable.Builder
import scala.annotation.unchecked.uncheckedVariance
import scala.collection.generic.IdleSignalling
import scala.collection.generic.Signalling

/** A template trait for mutable parallel maps. This trait is to be mixed in
 *  with concrete parallel maps to override the representation type.
 *
 *  $sideeffects
 *
 *  @tparam K    the key type of the map
 *  @tparam V    the value type of the map
 *
 *  @author Aleksandar Prokopec
 *  @since 2.9
 */
trait ParMapLike[K,
                 +V,
                 +Repr <: ParMapLike[K, V, Repr, Sequential] with ParMap[K, V],
                 +Sequential <: Map[K, V] with MapLike[K, V, Sequential]]
extends GenMapLike[K, V, Repr]
   with ParIterableLike[(K, V), Repr, Sequential]
{
self =>

  def default(key: K): V = throw new NoSuchElementException("key not found: " + key)

  def empty: Repr

  def apply(key: K) = get(key) match {
    case Some(v) => v
    case None => default(key)
  }

  def getOrElse[U >: V](key: K, default: => U): U = get(key) match {
    case Some(v) => v
    case None => default
  }

  def contains(key: K): Boolean = get(key).isDefined

  def isDefinedAt(key: K): Boolean = contains(key)

  private[this] def keysIterator(s: IterableSplitter[(K, V)] @uncheckedVariance): IterableSplitter[K] =
    new IterableSplitter[K] {
      i =>
      val iter = s
      def hasNext = iter.hasNext
      def next() = iter.next()._1
      def split = {
        val ss = iter.split.map(keysIterator(_))
        ss.foreach { _.signalDelegate = i.signalDelegate }
        ss
      }
      def remaining = iter.remaining
      def dup = keysIterator(iter.dup)
    }

  def keysIterator: IterableSplitter[K] = keysIterator(splitter)

  private[this] def valuesIterator(s: IterableSplitter[(K, V)] @uncheckedVariance): IterableSplitter[V] =
    new IterableSplitter[V] {
      i =>
      val iter = s
      def hasNext = iter.hasNext
      def next() = iter.next()._2
      def split = {
        val ss = iter.split.map(valuesIterator(_))
        ss.foreach { _.signalDelegate = i.signalDelegate }
        ss
      }
      def remaining = iter.remaining
      def dup = valuesIterator(iter.dup)
    }

  def valuesIterator: IterableSplitter[V] = valuesIterator(splitter)

  protected class DefaultKeySet extends ParSet[K] {
    def contains(key : K) = self.contains(key)
    def splitter = keysIterator(self.splitter)
    def + (elem: K): ParSet[K] =
      (ParSet[K]() ++ this + elem).asInstanceOf[ParSet[K]] // !!! concrete overrides abstract problem
    def - (elem: K): ParSet[K] =
      (ParSet[K]() ++ this - elem).asInstanceOf[ParSet[K]] // !!! concrete overrides abstract problem
    override def size = self.size
    override def foreach[S](f: K => S) = for ((k, v) <- self) f(k)
    override def seq = self.seq.keySet
  }

  protected class DefaultValuesIterable extends ParIterable[V] {
    def splitter = valuesIterator(self.splitter)
    override def size = self.size
    override def foreach[S](f: V => S) = for ((k, v) <- self) f(v)
    def seq = self.seq.values
  }

  def keySet: ParSet[K] = new DefaultKeySet

  def keys: ParIterable[K] = keySet

  def values: ParIterable[V] = new DefaultValuesIterable

  def filterKeys(p: K => Boolean): ParMap[K, V] = new ParMap[K, V] {
    lazy val filtered = self.filter(kv => p(kv._1))
    override def foreach[S](f: ((K, V)) => S): Unit = for (kv <- self) if (p(kv._1)) f(kv)
    def splitter = filtered.splitter
    override def contains(key: K) = self.contains(key) && p(key)
    def get(key: K) = if (!p(key)) None else self.get(key)
    def seq = self.seq.filterKeys(p)
    def size = filtered.size
    def + [U >: V](kv: (K, U)): ParMap[K, U] = ParMap[K, U]() ++ this + kv
    def - (key: K): ParMap[K, V] = ParMap[K, V]() ++ this - key
  }

  def mapValues[S](f: V => S): ParMap[K, S] = new ParMap[K, S] {
    override def foreach[Q](g: ((K, S)) => Q): Unit = for ((k, v) <- self) g((k, f(v)))
    def splitter = self.splitter.map(kv => (kv._1, f(kv._2)))
    override def size = self.size
    override def contains(key: K) = self.contains(key)
    def get(key: K) = self.get(key).map(f)
    def seq = self.seq.mapValues(f)
    def + [U >: S](kv: (K, U)): ParMap[K, U] = ParMap[K, U]() ++ this + kv
    def - (key: K): ParMap[K, S] = ParMap[K, S]() ++ this - key
  }

  // note - should not override toMap (could be mutable)
}