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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2007, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection.immutable
/** This class implements immutable sets with exactly three elements.
* @author Martin Oderskty
* @version 1.0, 019/01/2007
*/
@serializable
class Set3[A](elem1: A, elem2: A, elem3: A) extends Set[A] {
def empty[C]: Set[C] = new EmptySet[C]
def size: Int = 3
def contains(elem: A): Boolean =
elem == elem1 || elem == elem2 || elem == elem3
def + (elem: A): Set[A] =
if (contains(elem)) this
else new Set4(elem1, elem2, elem3, elem)
def - (elem: A): Set[A] =
if (elem == elem1) new Set2(elem2, elem3)
else if (elem == elem2) new Set2(elem1, elem3)
else if (elem == elem3) new Set2(elem1, elem2)
else this
def elements: Iterator[A] =
Iterator.fromValues(elem1, elem2, elem3)
}
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