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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection.immutable
import Predef.Pair
/** This class implements immutable maps with exactly one entry
*
* @author Martin Oderskty
* @version 1.0, 019/01/2007
*/
@serializable
class Map1[A, +B](key1: A, value1: B) extends Map[A, B] {
def size = 1
def get(key: A): Option[B] =
if (key == key1) Some(value1) else None
def elements = Iterator.single((key1, value1))
def empty[B]: Map[A, B] = new EmptyMap[A, B]
def update [B1 >: B](key: A, value: B1): Map[A, B1] =
if (key == key1) new Map1(key1, value)
else new Map2(key1, value1, key, value)
def - (key: A): Map[A, B] =
if (key == key1) empty else this
}
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