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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala.collection
import generic._
/** A default map which implements the `+` and `-` methods of maps.
*
* Instances that inherit from `DefaultMap[A, B]` still have to define:
* {{{
* def get(key: A): Option[B]
* def iterator: Iterator[(A, B)]
* }}}
* It refers back to the original map.
*
* It might also be advisable to override `foreach` or `size` if efficient
* implementations can be found.
*
* @since 2.8
*/
trait DefaultMap[A, +B] extends Map[A, B] { self =>
/** A default implementation which creates a new immutable map.
*/
override def +[B1 >: B](kv: (A, B1)): Map[A, B1] = {
val b = Map.newBuilder[A, B1]
b ++= this
b += ((kv._1, kv._2))
b.result
}
/** A default implementation which creates a new immutable map.
*/
override def - (key: A): Map[A, B] = {
val b = newBuilder
b ++= this filter (key != _._1)
b.result
}
}
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