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Standard library for the Scala Programming Language
/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala
package collection
package immutable
import scala.collection.immutable.Set.Set4
import scala.collection.mutable.{Builder, ReusableBuilder}
/** Base trait for immutable set collections */
trait Set[A] extends Iterable[A]
with collection.Set[A]
with SetOps[A, Set, Set[A]]
with IterableFactoryDefaults[A, Set] {
override def iterableFactory: IterableFactory[Set] = Set
}
/** Base trait for immutable set operations
*
* @define coll immutable set
* @define Coll `immutable.Set`
*/
trait SetOps[A, +CC[X], +C <: SetOps[A, CC, C]]
extends collection.SetOps[A, CC, C] {
/** Creates a new set with an additional element, unless the element is
* already present.
*
* @param elem the element to be added
* @return a new set that contains all elements of this set and that also
* contains `elem`.
*/
def incl(elem: A): C
/** Alias for `incl` */
override final def + (elem: A): C = incl(elem) // like in collection.Set but not deprecated
/** Creates a new set with a given element removed from this set.
*
* @param elem the element to be removed
* @return a new set that contains all elements of this set but that does not
* contain `elem`.
*/
def excl(elem: A): C
/** Alias for `excl` */
@`inline` final override def - (elem: A): C = excl(elem)
def diff(that: collection.Set[A]): C =
toIterable.foldLeft(empty)((result, elem) => if (that contains elem) result else result + elem)
/** Creates a new $coll from this $coll by removing all elements of another
* collection.
*
* @param that the collection containing the elements to remove.
* @return a new $coll with the given elements removed, omitting duplicates.
*/
def removedAll(that: IterableOnce[A]): C = that.iterator.foldLeft[C](coll)(_ - _)
/** Alias for removedAll */
override final def -- (that: IterableOnce[A]): C = removedAll(that)
}
trait StrictOptimizedSetOps[A, +CC[X], +C <: SetOps[A, CC, C]]
extends SetOps[A, CC, C]
with collection.StrictOptimizedSetOps[A, CC, C]
with StrictOptimizedIterableOps[A, CC, C] {
override def concat(that: collection.IterableOnce[A]): C = {
var result: C = coll
val it = that.iterator
while (it.hasNext) result = result + it.next()
result
}
}
/**
* $factoryInfo
* @define coll immutable set
* @define Coll `immutable.Set`
*/
@SerialVersionUID(3L)
object Set extends IterableFactory[Set] {
def empty[A]: Set[A] = EmptySet.asInstanceOf[Set[A]]
def from[E](it: collection.IterableOnce[E]): Set[E] =
it match {
// We want `SortedSet` (and subclasses, such as `BitSet`) to
// rebuild themselves to avoid element type widening issues
case _: SortedSet[E] => (newBuilder[E] ++= it).result()
case _ if it.knownSize == 0 => empty[E]
case s: Set[E] => s
case _ => (newBuilder[E] ++= it).result()
}
def newBuilder[A]: Builder[A, Set[A]] = new SetBuilderImpl[A]
/** An optimized representation for immutable empty sets */
@SerialVersionUID(3L)
private object EmptySet extends AbstractSet[Any] with Serializable {
override def size: Int = 0
override def isEmpty = true
override def knownSize: Int = size
override def filter(pred: Any => Boolean): Set[Any] = this
override def filterNot(pred: Any => Boolean): Set[Any] = this
override def removedAll(that: IterableOnce[Any]): Set[Any] = this
override def diff(that: collection.Set[Any]): Set[Any] = this
override def subsetOf(that: collection.Set[Any]): Boolean = true
override def intersect(that: collection.Set[Any]): Set[Any] = this
override def view: View[Any] = View.empty
def contains(elem: Any): Boolean = false
def incl(elem: Any): Set[Any] = new Set1(elem)
def excl(elem: Any): Set[Any] = this
def iterator: Iterator[Any] = Iterator.empty
override def foreach[U](f: Any => U): Unit = ()
}
private[collection] def emptyInstance: Set[Any] = EmptySet
@SerialVersionUID(3L)
private abstract class SetNIterator[A](n: Int) extends AbstractIterator[A] with Serializable {
private[this] var current = 0
private[this] var remainder = n
override def knownSize: Int = remainder
def hasNext = remainder > 0
def apply(i: Int): A
def next(): A =
if (hasNext) {
val r = apply(current)
current += 1
remainder -= 1
r
} else Iterator.empty.next()
override def drop(n: Int): Iterator[A] = {
if (n > 0) {
current += n
remainder = Math.max(0, remainder - n)
}
this
}
}
/** An optimized representation for immutable sets of size 1 */
@SerialVersionUID(3L)
final class Set1[A] private[collection] (elem1: A) extends AbstractSet[A] with StrictOptimizedIterableOps[A, Set, Set[A]] with Serializable {
override def size: Int = 1
override def isEmpty = false
override def knownSize: Int = size
def contains(elem: A): Boolean = elem == elem1
def incl(elem: A): Set[A] =
if (contains(elem)) this
else new Set2(elem1, elem)
def excl(elem: A): Set[A] =
if (elem == elem1) Set.empty
else this
def iterator: Iterator[A] = Iterator.single(elem1)
override def foreach[U](f: A => U): Unit = f(elem1)
override def exists(p: A => Boolean): Boolean = p(elem1)
override def forall(p: A => Boolean): Boolean = p(elem1)
override protected[collection] def filterImpl(pred: A => Boolean, isFlipped: Boolean): Set[A] =
if (pred(elem1) != isFlipped) this else Set.empty
override def find(p: A => Boolean): Option[A] =
if (p(elem1)) Some(elem1)
else None
override def head: A = elem1
override def tail: Set[A] = Set.empty
}
/** An optimized representation for immutable sets of size 2 */
@SerialVersionUID(3L)
final class Set2[A] private[collection] (elem1: A, elem2: A) extends AbstractSet[A] with StrictOptimizedIterableOps[A, Set, Set[A]] with Serializable {
override def size: Int = 2
override def isEmpty = false
override def knownSize: Int = size
def contains(elem: A): Boolean = elem == elem1 || elem == elem2
def incl(elem: A): Set[A] =
if (contains(elem)) this
else new Set3(elem1, elem2, elem)
def excl(elem: A): Set[A] =
if (elem == elem1) new Set1(elem2)
else if (elem == elem2) new Set1(elem1)
else this
def iterator: Iterator[A] = new SetNIterator[A](size) {
def apply(i: Int) = getElem(i)
}
private def getElem(i: Int) = i match { case 0 => elem1 case 1 => elem2 }
override def foreach[U](f: A => U): Unit = {
f(elem1); f(elem2)
}
override def exists(p: A => Boolean): Boolean = {
p(elem1) || p(elem2)
}
override def forall(p: A => Boolean): Boolean = {
p(elem1) && p(elem2)
}
override protected[collection] def filterImpl(pred: A => Boolean, isFlipped: Boolean): Set[A] = {
var r1: A = null.asInstanceOf[A]
var n = 0
if (pred(elem1) != isFlipped) { r1 = elem1; n += 1}
if (pred(elem2) != isFlipped) { if (n == 0) r1 = elem2; n += 1}
n match {
case 0 => Set.empty
case 1 => new Set1(r1)
case 2 => this
}
}
override def find(p: A => Boolean): Option[A] = {
if (p(elem1)) Some(elem1)
else if (p(elem2)) Some(elem2)
else None
}
override def head: A = elem1
override def tail: Set[A] = new Set1(elem2)
}
/** An optimized representation for immutable sets of size 3 */
@SerialVersionUID(3L)
final class Set3[A] private[collection] (elem1: A, elem2: A, elem3: A) extends AbstractSet[A] with StrictOptimizedIterableOps[A, Set, Set[A]] with Serializable {
override def size: Int = 3
override def isEmpty = false
override def knownSize: Int = size
def contains(elem: A): Boolean =
elem == elem1 || elem == elem2 || elem == elem3
def incl(elem: A): Set[A] =
if (contains(elem)) this
else new Set4(elem1, elem2, elem3, elem)
def excl(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] = new SetNIterator[A](size) {
def apply(i: Int) = getElem(i)
}
private def getElem(i: Int) = i match { case 0 => elem1 case 1 => elem2 case 2 => elem3 }
override def foreach[U](f: A => U): Unit = {
f(elem1); f(elem2); f(elem3)
}
override def exists(p: A => Boolean): Boolean = {
p(elem1) || p(elem2) || p(elem3)
}
override def forall(p: A => Boolean): Boolean = {
p(elem1) && p(elem2) && p(elem3)
}
override protected[collection] def filterImpl(pred: A => Boolean, isFlipped: Boolean): Set[A] = {
var r1, r2: A = null.asInstanceOf[A]
var n = 0
if (pred(elem1) != isFlipped) { r1 = elem1; n += 1}
if (pred(elem2) != isFlipped) { if (n == 0) r1 = elem2 else r2 = elem2; n += 1}
if (pred(elem3) != isFlipped) { if (n == 0) r1 = elem3 else if (n == 1) r2 = elem3; n += 1}
n match {
case 0 => Set.empty
case 1 => new Set1(r1)
case 2 => new Set2(r1, r2)
case 3 => this
}
}
override def find(p: A => Boolean): Option[A] = {
if (p(elem1)) Some(elem1)
else if (p(elem2)) Some(elem2)
else if (p(elem3)) Some(elem3)
else None
}
override def head: A = elem1
override def tail: Set[A] = new Set2(elem2, elem3)
}
/** An optimized representation for immutable sets of size 4 */
@SerialVersionUID(3L)
final class Set4[A] private[collection] (elem1: A, elem2: A, elem3: A, elem4: A) extends AbstractSet[A] with StrictOptimizedIterableOps[A, Set, Set[A]] with Serializable {
override def size: Int = 4
override def isEmpty = false
override def knownSize: Int = size
def contains(elem: A): Boolean =
elem == elem1 || elem == elem2 || elem == elem3 || elem == elem4
def incl(elem: A): Set[A] =
if (contains(elem)) this
else HashSet.empty[A] + elem1 + elem2 + elem3 + elem4 + elem
def excl(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] = new SetNIterator[A](size) {
def apply(i: Int) = getElem(i)
}
private def getElem(i: Int) = i match { case 0 => elem1 case 1 => elem2 case 2 => elem3 case 3 => elem4 }
override def foreach[U](f: A => U): Unit = {
f(elem1); f(elem2); f(elem3); f(elem4)
}
override def exists(p: A => Boolean): Boolean = {
p(elem1) || p(elem2) || p(elem3) || p(elem4)
}
override def forall(p: A => Boolean): Boolean = {
p(elem1) && p(elem2) && p(elem3) && p(elem4)
}
override protected[collection] def filterImpl(pred: A => Boolean, isFlipped: Boolean): Set[A] = {
var r1, r2, r3: A = null.asInstanceOf[A]
var n = 0
if (pred(elem1) != isFlipped) { r1 = elem1; n += 1}
if (pred(elem2) != isFlipped) { if (n == 0) r1 = elem2 else r2 = elem2; n += 1}
if (pred(elem3) != isFlipped) { if (n == 0) r1 = elem3 else if (n == 1) r2 = elem3 else r3 = elem3; n += 1}
if (pred(elem4) != isFlipped) { if (n == 0) r1 = elem4 else if (n == 1) r2 = elem4 else if (n == 2) r3 = elem4; n += 1}
n match {
case 0 => Set.empty
case 1 => new Set1(r1)
case 2 => new Set2(r1, r2)
case 3 => new Set3(r1, r2, r3)
case 4 => this
}
}
override def find(p: A => Boolean): Option[A] = {
if (p(elem1)) Some(elem1)
else if (p(elem2)) Some(elem2)
else if (p(elem3)) Some(elem3)
else if (p(elem4)) Some(elem4)
else None
}
override def head: A = elem1
override def tail: Set[A] = new Set3(elem2, elem3, elem4)
private[immutable] def buildTo(builder: Builder[A, Set[A]]): builder.type =
builder.addOne(elem1).addOne(elem2).addOne(elem3).addOne(elem4)
}
}
/** Explicit instantiation of the `Set` trait to reduce class file size in subclasses. */
abstract class AbstractSet[A] extends scala.collection.AbstractSet[A] with Set[A]
/** Builder for Set.
* $multipleResults
*/
private final class SetBuilderImpl[A] extends ReusableBuilder[A, Set[A]] {
private[this] var elems: Set[A] = Set.empty
private[this] var switchedToHashSetBuilder: Boolean = false
private[this] var hashSetBuilder: HashSetBuilder[A] = _
override def clear(): Unit = {
elems = Set.empty
if (hashSetBuilder != null) {
hashSetBuilder.clear()
}
switchedToHashSetBuilder = false
}
override def result(): Set[A] =
if (switchedToHashSetBuilder) hashSetBuilder.result() else elems
def addOne(elem: A) = {
if (switchedToHashSetBuilder) {
hashSetBuilder.addOne(elem)
} else if (elems.size < 4) {
elems = elems + elem
} else {
// assert(elems.size == 4)
if (elems.contains(elem)) {
() // do nothing
} else {
switchedToHashSetBuilder = true
if (hashSetBuilder == null) {
hashSetBuilder = new HashSetBuilder
}
elems.asInstanceOf[Set4[A]].buildTo(hashSetBuilder)
hashSetBuilder.addOne(elem)
}
}
this
}
override def addAll(xs: IterableOnce[A]): this.type =
if (switchedToHashSetBuilder) {
hashSetBuilder.addAll(xs)
this
} else {
super.addAll(xs)
}
}