scala.collection.parallel.mutable.LazyCombiner

trait LazyCombiner[Elem, +To, Buff <: Growable[Elem] with Sizing] extends Combiner[Elem, To]

Implements combining contents of two combiners by postponing the operation until result method is called. It chains the leaf results together instead of evaluating the actual collection.

Concrete Value Members From scala.collection.generic.Growable

def ++=(xs: TraversableOnce[Elem]): LazyCombiner.this.type

adds all elements produced by a TraversableOnce to this growable collection.

  • xs
    • the TraversableOnce producing the elements to add.
  • returns
    • the growable collection itself.
  • Definition Classes
    • Growable

(defined at scala.collection.generic.Growable)

def +=(elem1: Elem, elem2: Elem, elems: Elem*): LazyCombiner.this.type

adds two or more elements to this growable collection.

  • elem1
    • the first element to add.
  • elem2
    • the second element to add.
  • elems
    • the remaining elements to add.
  • returns
    • the growable collection itself
  • Definition Classes
    • Growable

(defined at scala.collection.generic.Growable)

Concrete Value Members From scala.collection.mutable.Builder

def mapResult[NewTo](f: (To) ⇒ NewTo): Builder[Elem, NewTo]

Creates a new builder by applying a transformation function to the results of this builder.

  • NewTo
    • the type of collection returned by f .
  • f
    • the transformation function.
  • returns
    • a new builder which is the same as the current builder except that a transformation function is applied to this builder’s result.
  • Definition Classes
    • Builder
  • Note
    • The original builder should no longer be used after mapResult is called.

(defined at scala.collection.mutable.Builder)

def sizeHint(size: Int): Unit

Gives a hint how many elements are expected to be added when the next result is called. Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • size
    • the hint how many elements will be added.
  • Definition Classes
    • Builder

(defined at scala.collection.mutable.Builder)

def sizeHint(coll: TraversableLike[_, _]): Unit

Gives a hint that one expects the result of this builder to have the same size as the given collection, plus some delta. This will provide a hint only if the collection is known to have a cheap size method. Currently this is assumed to be the case if and only if the collection is of type IndexedSeqLike . Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • coll
    • the collection which serves as a hint for the result’s size.
  • Definition Classes
    • Builder

(defined at scala.collection.mutable.Builder)

def sizeHint(coll: TraversableLike[_, _], delta: Int): Unit

Gives a hint that one expects the result of this builder to have the same size as the given collection, plus some delta. This will provide a hint only if the collection is known to have a cheap size method. Currently this is assumed to be the case if and only if the collection is of type IndexedSeqLike . Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • coll
    • the collection which serves as a hint for the result’s size.
  • delta
    • a correction to add to the coll.size to produce the size hint.
  • Definition Classes
    • Builder

(defined at scala.collection.mutable.Builder)

def sizeHintBounded(size: Int, boundingColl: TraversableLike[_, _]): Unit

Gives a hint how many elements are expected to be added when the next result is called, together with an upper bound given by the size of some other collection. Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

  • size
    • the hint how many elements will be added.
  • boundingColl
    • the bounding collection. If it is an IndexedSeqLike, then sizes larger than collection’s size are reduced.
  • Definition Classes
    • Builder

(defined at scala.collection.mutable.Builder)

Concrete Value Members From scala.collection.parallel.Combiner

var _combinerTaskSupport: TaskSupport

  • Definition Classes
    • Combiner

(defined at scala.collection.parallel.Combiner)

def combinerTaskSupport: TaskSupport

  • Definition Classes
    • Combiner

(defined at scala.collection.parallel.Combiner)

def combinerTaskSupport_=(cts: TaskSupport): Unit

  • Definition Classes
    • Combiner

(defined at scala.collection.parallel.Combiner)

Abstract Value Members From scala.collection.parallel.mutable.LazyCombiner

abstract val chain: ArrayBuffer[Buff]

(defined at scala.collection.parallel.mutable.LazyCombiner)

abstract def newLazyCombiner(buffchain: ArrayBuffer[Buff]): LazyCombiner[Elem, To, Buff]

(defined at scala.collection.parallel.mutable.LazyCombiner)

Concrete Value Members From scala.collection.parallel.mutable.LazyCombiner

abstract def allocateAndCopy: To

Method that allocates the data structure and copies elements into it using size and chain members.

(defined at scala.collection.parallel.mutable.LazyCombiner)

def +=(elem: Elem): LazyCombiner.this.type

Adds a single element to the builder.

  • elem
    • the element to be added.
  • returns
    • the builder itself.
  • Definition Classes
    • LazyCombiner → Builder → Growable

(defined at scala.collection.parallel.mutable.LazyCombiner)

def combine[N <: Elem, NewTo >: To](other: Combiner[N, NewTo]): Combiner[N, NewTo]

Combines the contents of the receiver builder and the other builder, producing a new builder containing both their elements.

This method may combine the two builders by copying them into a larger collection, by producing a lazy view that gets evaluated once result is invoked, or use a merge operation specific to the data structure in question.

Note that both the receiver builder and other builder become invalidated after the invocation of this method, and should be cleared (see clear ) if they are to be used again.

Also, combining two combiners c1 and c2 for which c1 eq c2 is true , that is, they are the same objects in memory:

c1.combine(c2)

always does nothing and returns c1 .

  • N
    • the type of elements contained by the other builder
  • NewTo
    • the type of collection produced by the other builder
  • other
    • the other builder
  • returns
    • the parallel builder containing both the elements of this and the other builder
  • Definition Classes
    • LazyCombiner → Combiner

(defined at scala.collection.parallel.mutable.LazyCombiner)

Concrete Value Members From Implicit scala.collection.parallel.CollectionsHaveToParArray ——————————————————————————–

def toParArray: ParArray[T]

  • Implicit information
    • This member is added by an implicit conversion from LazyCombiner [Elem, To, Buff] to CollectionsHaveToParArray [LazyCombiner [Elem, To, Buff], T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type ( LazyCombiner [Elem, To, Buff]) ⇒ GenTraversableOnce [T] is in scope.
  • Definition Classes
    • CollectionsHaveToParArray (added by implicit convertion: scala.collection.parallel.CollectionsHaveToParArray)

Full Source:

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

package scala
package collection.parallel.mutable

import scala.collection.generic.Growable
import scala.collection.generic.Sizing
import scala.collection.mutable.ArrayBuffer
import scala.collection.parallel.Combiner

/** Implements combining contents of two combiners
 *  by postponing the operation until `result` method is called. It chains
 *  the leaf results together instead of evaluating the actual collection.
 *
 *  @tparam Elem    the type of the elements in the combiner
 *  @tparam To      the type of the collection the combiner produces
 *  @tparam Buff    the type of the buffers that contain leaf results and this combiner chains together
 */
trait LazyCombiner[Elem, +To, Buff <: Growable[Elem] with Sizing] extends Combiner[Elem, To] {
//self: scala.collection.parallel.EnvironmentPassingCombiner[Elem, To] =>
  val chain: ArrayBuffer[Buff]
  val lastbuff = chain.last
  def +=(elem: Elem) = { lastbuff += elem; this }
  def result: To = allocateAndCopy
  def clear() = { chain.clear() }
  def combine[N <: Elem, NewTo >: To](other: Combiner[N, NewTo]): Combiner[N, NewTo] = if (this ne other) {
    import language.existentials // FIXME: See SI-7750
    if (other.isInstanceOf[LazyCombiner[_, _, _]]) {
      val that = other.asInstanceOf[LazyCombiner[Elem, To, Buff]]
      newLazyCombiner(chain ++= that.chain)
    } else throw new UnsupportedOperationException("Cannot combine with combiner of different type.")
  } else this
  def size = chain.foldLeft(0)(_ + _.size)

  /** Method that allocates the data structure and copies elements into it using
   *  `size` and `chain` members.
   */
  def allocateAndCopy: To
  def newLazyCombiner(buffchain: ArrayBuffer[Buff]): LazyCombiner[Elem, To, Buff]
}