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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala.collection
package immutable
import generic._
import parallel.immutable.ParSet
/** A generic trait for immutable sets.
* $setNote
* $setTags
*
* @since 1.0
* @author Matthias Zenger
* @author Martin Odersky
* @define Coll `immutable.Set`
* @define coll immutable set
*/
trait Set[A] extends Iterable[A]
// with GenSet[A]
with scala.collection.Set[A]
with GenericSetTemplate[A, Set]
with SetLike[A, Set[A]]
with Parallelizable[A, ParSet[A]]
{
override def companion: GenericCompanion[Set] = Set
override def toSet[B >: A]: Set[B] = this.asInstanceOf[Set[B]]
override def seq: Set[A] = this
protected override def parCombiner = ParSet.newCombiner[A] // if `immutable.SetLike` gets introduced, please move this there!
}
/** $factoryInfo
* @define Coll `immutable.Set`
* @define coll immutable set
*/
object Set extends ImmutableSetFactory[Set] {
/** $setCanBuildFromInfo */
implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, Set[A]] = setCanBuildFrom[A]
override def empty[A]: Set[A] = EmptySet.asInstanceOf[Set[A]]
/** An optimized representation for immutable empty sets */
private object EmptySet extends AbstractSet[Any] with Set[Any] with Serializable {
override def size: Int = 0
def contains(elem: Any): Boolean = false
def + (elem: Any): Set[Any] = new Set1(elem)
def - (elem: Any): Set[Any] = this
def iterator: Iterator[Any] = Iterator.empty
override def foreach[U](f: Any => U): Unit = {}
}
/** An optimized representation for immutable sets of size 1 */
@SerialVersionUID(1233385750652442003L)
class Set1[A] private[collection] (elem1: A) extends AbstractSet[A] with Set[A] with Serializable {
override def size: Int = 1
def contains(elem: A): Boolean =
elem == elem1
def + (elem: A): Set[A] =
if (contains(elem)) this
else new Set2(elem1, elem)
def - (elem: A): Set[A] =
if (elem == elem1) Set.empty
else this
def iterator: Iterator[A] =
Iterator(elem1)
override def foreach[U](f: A => U): Unit = {
f(elem1)
}
}
/** An optimized representation for immutable sets of size 2 */
@SerialVersionUID(-6443011234944830092L)
class Set2[A] private[collection] (elem1: A, elem2: A) extends AbstractSet[A] with Set[A] with Serializable {
override def size: Int = 2
def contains(elem: A): Boolean =
elem == elem1 || elem == elem2
def + (elem: A): Set[A] =
if (contains(elem)) this
else new Set3(elem1, elem2, elem)
def - (elem: A): Set[A] =
if (elem == elem1) new Set1(elem2)
else if (elem == elem2) new Set1(elem1)
else this
def iterator: Iterator[A] =
Iterator(elem1, elem2)
override def foreach[U](f: A => U): Unit = {
f(elem1); f(elem2)
}
}
/** An optimized representation for immutable sets of size 3 */
@SerialVersionUID(-3590273538119220064L)
class Set3[A] private[collection] (elem1: A, elem2: A, elem3: A) extends AbstractSet[A] with Set[A] with Serializable {
override 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 iterator: Iterator[A] =
Iterator(elem1, elem2, elem3)
override def foreach[U](f: A => U): Unit = {
f(elem1); f(elem2); f(elem3)
}
}
/** An optimized representation for immutable sets of size 4 */
@SerialVersionUID(-3622399588156184395L)
class Set4[A] private[collection] (elem1: A, elem2: A, elem3: A, elem4: A) extends AbstractSet[A] with Set[A] with Serializable {
override def size: Int = 4
def contains(elem: A): Boolean =
elem == elem1 || elem == elem2 || elem == elem3 || elem == elem4
def + (elem: A): Set[A] =
if (contains(elem)) this
else new HashSet[A] + (elem1, elem2, elem3, elem4, elem)
def - (elem: A): Set[A] =
if (elem == elem1) new Set3(elem2, elem3, elem4)
else if (elem == elem2) new Set3(elem1, elem3, elem4)
else if (elem == elem3) new Set3(elem1, elem2, elem4)
else if (elem == elem4) new Set3(elem1, elem2, elem3)
else this
def iterator: Iterator[A] =
Iterator(elem1, elem2, elem3, elem4)
override def foreach[U](f: A => U): Unit = {
f(elem1); f(elem2); f(elem3); f(elem4)
}
}
}
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