Scala example source code file (Map.scala)

This example Scala source code file (Map.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, abstractiterable, abstractmap, b, canbuildfrom, map, mapfactory, serializable, some, withdefault

The Map.scala Scala example source code

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

package scala
package collection

import generic._

/**
 *  A map from keys of type `A` to values of type `B`.
 *
 *  $mapNote
 *
 *  '''Note:''' If you do not have specific implementations for `add` and `-` in mind,
 *        you might consider inheriting from `DefaultMap` instead.
 *
 *  '''Note:''' If your additions and mutations return the same kind of map as the map
 *        you are defining, you should inherit from `MapLike` as well.
 *
 *  @tparam A     the type of the keys in this map.
 *  @tparam B     the type of the values associated with keys.
 *
 *  @since 1.0
 */
trait Map[A, +B] extends Iterable[(A, B)] with GenMap[A, B] with MapLike[A, B, Map[A, B]] {
  def empty: Map[A, B] = Map.empty

  override def seq: Map[A, B] = this
}

/** $factoryInfo
 *  @define Coll `Map`
 *  @define coll map
 */
object Map extends MapFactory[Map] {
  def empty[A, B]: immutable.Map[A, B] = immutable.Map.empty

  /** $mapCanBuildFromInfo */
  implicit def canBuildFrom[A, B]: CanBuildFrom[Coll, (A, B), Map[A, B]] = new MapCanBuildFrom[A, B]

  /** An abstract shell used by { mutable, immutable }.Map but not by collection.Map
   *  because of variance issues.
   */
  abstract class WithDefault[A, +B](underlying: Map[A, B], d: A => B) extends AbstractMap[A, B] with Map[A, B] with Serializable {
    override def size               = underlying.size
    def get(key: A)                 = underlying.get(key) // removed in 2.9: orElse Some(default(key))
    def iterator                    = underlying.iterator
    override def default(key: A): B = d(key)
  }

}

/** Explicit instantiation of the `Map` trait to reduce class file size in subclasses. */
abstract class AbstractMap[A, +B] extends AbstractIterable[(A, B)] with Map[A, B]