scala.collection.mutable.MapBuilder

class MapBuilder[A, B, Coll <: GenMap[A, B] with GenMapLike[A, B, Coll]] extends ReusableBuilder[(A, B), Coll]

The canonical builder for immutable maps, working with the map’s + method to add new elements. Collections are built from their empty element using this + method.

Value Members From scala.collection.generic.Growable

def ++=(xs: TraversableOnce[(A, B)]): MapBuilder.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: (A, B), elem2: (A, B), elems: (A, B)*): MapBuilder.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)

Value Members From scala.collection.mutable.Builder

def mapResult[NewTo](f: (Coll) ⇒ NewTo): Builder[(A, B), 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)

Instance Constructors From scala.collection.mutable.MapBuilder

new MapBuilder(empty: Coll)

  • empty
    • The empty element of the collection.

(defined at scala.collection.mutable.MapBuilder)

Value Members From scala.collection.mutable.MapBuilder

def +=(x: (A, B)): MapBuilder.this.type

Adds a single element to the builder.

  • returns
    • the builder itself.
  • Definition Classes
    • MapBuilder → Builder → Growable

(defined at scala.collection.mutable.MapBuilder)

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

def toParArray: ParArray[T]

  • Implicit information
    • This member is added by an implicit conversion from MapBuilder [A, B, Coll] to CollectionsHaveToParArray [MapBuilder [A, B, Coll], T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type (MapBuilder [A, B, Coll]) ⇒ 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
package mutable

/** The canonical builder for immutable maps, working with the map's `+` method
 *  to add new elements.
 *  Collections are built from their `empty` element using this + method.
 *
 *  @tparam A      Type of the keys for the map this builder creates.
 *  @tparam B      Type of the values for the map this builder creates.
 *  @tparam Coll   The type of the actual collection this builder builds.
 *  @param empty   The empty element of the collection.
 *
 *  @since 2.8
 */
class MapBuilder[A, B, Coll <: scala.collection.GenMap[A, B] with scala.collection.GenMapLike[A, B, Coll]](empty: Coll)
extends ReusableBuilder[(A, B), Coll] {
  protected var elems: Coll = empty
  def +=(x: (A, B)): this.type = {
    elems = (elems + x).asInstanceOf[Coll]
      // the cast is necessary because right now we cannot enforce statically that
      // for every map of type Coll, `+` yields again a Coll. With better support
      // for hk-types we might be able to enforce this in the future, though.
    this
  }
  def clear() { elems = empty }
  def result: Coll = elems
}