Scala example source code file (GenMapFactory.scala)

This example Scala source code file (GenMapFactory.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

a, b, canbuildfrom, cc, coll, genmap, genmapfactory, genmaplike, mapbuilder, mapcanbuildfrom

The GenMapFactory.scala Scala example source code

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

package scala
package collection
package generic

import mutable.{Builder, MapBuilder}
import scala.language.higherKinds

/** A template for companion objects of `Map` and subclasses thereof.
 *
 *  @define coll map
 *  @define Coll `Map`
 *  @define factoryInfo
 *    This object provides a set of operations needed to create `$Coll` values.
 *    @author Martin Odersky
 *    @version 2.8
 *    @since 2.8
 *  @define canBuildFromInfo
 *    The standard `CanBuildFrom` instance for `$Coll` objects.
 *    @see CanBuildFrom
 *  @define mapCanBuildFromInfo
 *    The standard `CanBuildFrom` instance for `$Coll` objects.
 *    The created value is an instance of class `MapCanBuildFrom`.
 *    @see CanBuildFrom
 *    @see GenericCanBuildFrom
 */
abstract class GenMapFactory[CC[A, B] <: GenMap[A, B] with GenMapLike[A, B, CC[A, B]]] {

  /** The type constructor of the collection that can be built by this factory */
  type Coll = CC[_, _]

  /** An empty $Coll */
  def empty[A, B]: CC[A, B]

  /** A collection of type $Coll that contains given key/value bindings.
   *  @param elems   the key/value pairs that make up the $coll
   *  @tparam A      the type of the keys
   *  @tparam B      the type of the associated values
   *  @return        a new $coll consisting key/value pairs given by `elems`.
   */
  def apply[A, B](elems: (A, B)*): CC[A, B] = (newBuilder[A, B] ++= elems).result()

  /** The default builder for $Coll objects.
   *  @tparam A      the type of the keys
   *  @tparam B      the type of the associated values
   */
  def newBuilder[A, B]: Builder[(A, B), CC[A, B]] = new MapBuilder[A, B, CC[A, B]](empty[A, B])

  /** The standard `CanBuildFrom` class for maps.
   */
  class MapCanBuildFrom[A, B] extends CanBuildFrom[Coll, (A, B), CC[A, B]] {
    def apply(from: Coll) = newBuilder[A, B]
    def apply() = newBuilder
  }
}