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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection
import generic._
/** A map from keys of type A to values of type B.
* To implement a concrete map, you need to provide implementations of the following methods:
* (where This is the type of the map in question):
*
* def get(key: A): Option[B]
* def elements: Iterator[(A, B)]
* def add[B1 >: B](key: A, value: B1): This
* def -(key: A): This
*
* If you wish that methods like, take, drop, filter return the same kind of map, you should also
* override:
*
* def empty: This
*
* It might also be a good idea to override methods foreach and size for efficiency.
*
* @note If you do not have speicifc implementations for `add` and `-` in mind, you
* might consider inheriting from `DefaultMap` instead.
*
* @note Of you additions and mutations return the same kind of map as the map you are defining,
* you should inherit from `MapTemplate` as well.
*/
trait Map[A, +B] extends Iterable[(A, B)] with MapTemplate[A, B, Map[A, B]] {
def empty: Map[A, B] = Map.empty
override protected[this] def newBuilder : Builder[(A, B), Map[A, B], Any] =
throw new UnsupportedOperationException("Map.newBuilder")
def mapBuilder[A, B]: Builder[(A, B), Map[A, B], Any] = Map.newBuilder[A, B]
}
/* Factory object for `Map` class */
object Map extends ImmutableMapFactory[immutable.Map] {
type Coll = Map[_, _]
def empty[A, B]: immutable.Map[A, B] = immutable.Map.empty
implicit def builderFactory[A, B]: BuilderFactory[(A, B), Map[A, B], Coll] = new BuilderFactory[(A, B), Map[A, B], Coll] { def apply(from: Coll) = from.mapBuilder[A, B] }
}
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