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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.generic.{BitOperations, CanBuildFrom}
import scala.collection.mutable.{Builder, MapBuilder}
import scala.annotation.tailrec
/** Utility class for integer maps.
* @author David MacIver
*/
private[immutable] object IntMapUtils extends BitOperations.Int {
def branchMask(i: Int, j: Int) = highestOneBit(i ^ j)
def join[T](p1: Int, t1: IntMap[T], p2: Int, t2: IntMap[T]): IntMap[T] = {
val m = branchMask(p1, p2)
val p = mask(p1, m)
if (zero(p1, m)) IntMap.Bin(p, m, t1, t2)
else IntMap.Bin(p, m, t2, t1)
}
def bin[T](prefix: Int, mask: Int, left: IntMap[T], right: IntMap[T]): IntMap[T] = (left, right) match {
case (left, IntMap.Nil) => left
case (IntMap.Nil, right) => right
case (left, right) => IntMap.Bin(prefix, mask, left, right)
}
}
import IntMapUtils._
/** A companion object for integer maps.
*
* @define Coll `IntMap`
* @define mapCanBuildFromInfo
* The standard `CanBuildFrom` instance for `$Coll` objects.
* The created value is an instance of class `MapCanBuildFrom`.
* @since 2.7
*/
object IntMap {
/** $mapCanBuildFromInfo */
implicit def canBuildFrom[A, B]: CanBuildFrom[IntMap[A], (Int, B), IntMap[B]] =
ReusableCBF.asInstanceOf[CanBuildFrom[IntMap[A], (Int, B), IntMap[B]]]
private val ReusableCBF = new CanBuildFrom[IntMap[Any], (Int, Any), IntMap[Any]] {
def apply(from: IntMap[Any]): Builder[(Int, Any), IntMap[Any]] = apply()
def apply(): Builder[(Int, Any), IntMap[Any]] = new MapBuilder[Int, Any, IntMap[Any]](empty[Any])
}
def empty[T] : IntMap[T] = IntMap.Nil
def singleton[T](key: Int, value: T): IntMap[T] = IntMap.Tip(key, value)
def apply[T](elems: (Int, T)*): IntMap[T] =
elems.foldLeft(empty[T])((x, y) => x.updated(y._1, y._2))
private[immutable] case object Nil extends IntMap[Nothing] {
// Important! Without this equals method in place, an infinite
// loop from Map.equals => size => pattern-match-on-Nil => equals
// develops. Case objects and custom equality don't mix without
// careful handling.
override def equals(that : Any) = that match {
case _: this.type => true
case _: IntMap[_] => false // The only empty IntMaps are eq Nil
case _ => super.equals(that)
}
}
private[immutable] case class Tip[+T](key: Int, value: T) extends IntMap[T]{
def withValue[S](s: S) =
if (s.asInstanceOf[AnyRef] eq value.asInstanceOf[AnyRef]) this.asInstanceOf[IntMap.Tip[S]]
else IntMap.Tip(key, s)
}
private[immutable] case class Bin[+T](prefix: Int, mask: Int, left: IntMap[T], right: IntMap[T]) extends IntMap[T] {
def bin[S](left: IntMap[S], right: IntMap[S]): IntMap[S] = {
if ((this.left eq left) && (this.right eq right)) this.asInstanceOf[IntMap.Bin[S]]
else IntMap.Bin[S](prefix, mask, left, right)
}
}
}
import IntMap._
// Iterator over a non-empty IntMap.
private[immutable] abstract class IntMapIterator[V, T](it: IntMap[V]) extends AbstractIterator[T] {
// Basically this uses a simple stack to emulate conversion over the tree. However
// because we know that Ints are at least 32 bits we can have at most 32 IntMap.Bins and
// one IntMap.Tip sitting on the tree at any point. Therefore we know the maximum stack
// depth is 33 and
var index = 0
var buffer = new Array[AnyRef](33)
def pop = {
index -= 1
buffer(index).asInstanceOf[IntMap[V]]
}
def push(x: IntMap[V]) {
buffer(index) = x.asInstanceOf[AnyRef]
index += 1
}
push(it)
/**
* What value do we assign to a tip?
*/
def valueOf(tip: IntMap.Tip[V]): T
def hasNext = index != 0
final def next: T =
pop match {
case IntMap.Bin(_,_, [email protected](_, _), right) => {
push(right)
valueOf(t)
}
case IntMap.Bin(_, _, left, right) => {
push(right)
push(left)
next
}
case [email protected](_, _) => valueOf(t)
// This should never happen. We don't allow IntMap.Nil in subtrees of the IntMap
// and don't return an IntMapIterator for IntMap.Nil.
case IntMap.Nil => sys.error("Empty maps not allowed as subtrees")
}
}
private[immutable] class IntMapEntryIterator[V](it: IntMap[V]) extends IntMapIterator[V, (Int, V)](it) {
def valueOf(tip: IntMap.Tip[V]) = (tip.key, tip.value)
}
private[immutable] class IntMapValueIterator[V](it: IntMap[V]) extends IntMapIterator[V, V](it) {
def valueOf(tip: IntMap.Tip[V]) = tip.value
}
private[immutable] class IntMapKeyIterator[V](it: IntMap[V]) extends IntMapIterator[V, Int](it) {
def valueOf(tip: IntMap.Tip[V]) = tip.key
}
import IntMap._
/** Specialised immutable map structure for integer keys, based on
* [[http://ittc.ku.edu/~andygill/papers/IntMap98.pdf Fast Mergeable Integer Maps]]
* by Okasaki and Gill. Essentially a trie based on binary digits of the integers.
*
* '''Note:''' This class is as of 2.8 largely superseded by HashMap.
*
* @tparam T type of the values associated with integer keys.
*
* @since 2.7
* @define Coll `immutable.IntMap`
* @define coll immutable integer map
* @define mayNotTerminateInf
* @define willNotTerminateInf
*/
sealed abstract class IntMap[+T] extends AbstractMap[Int, T]
with Map[Int, T]
with MapLike[Int, T, IntMap[T]] {
override def empty: IntMap[T] = IntMap.Nil
override def toList = {
val buffer = new scala.collection.mutable.ListBuffer[(Int, T)]
foreach(buffer += _)
buffer.toList
}
/**
* Iterator over key, value pairs of the map in unsigned order of the keys.
*
* @return an iterator over pairs of integer keys and corresponding values.
*/
def iterator: Iterator[(Int, T)] = this match {
case IntMap.Nil => Iterator.empty
case _ => new IntMapEntryIterator(this)
}
/**
* Loops over the key, value pairs of the map in unsigned order of the keys.
*/
override final def foreach[U](f: ((Int, T)) => U): Unit = this match {
case IntMap.Bin(_, _, left, right) => { left.foreach(f); right.foreach(f) }
case IntMap.Tip(key, value) => f((key, value))
case IntMap.Nil =>
}
override def keysIterator: Iterator[Int] = this match {
case IntMap.Nil => Iterator.empty
case _ => new IntMapKeyIterator(this)
}
/**
* Loop over the keys of the map. The same as `keys.foreach(f)`, but may
* be more efficient.
*
* @param f The loop body
*/
final def foreachKey(f: Int => Unit): Unit = this match {
case IntMap.Bin(_, _, left, right) => { left.foreachKey(f); right.foreachKey(f) }
case IntMap.Tip(key, _) => f(key)
case IntMap.Nil =>
}
override def valuesIterator: Iterator[T] = this match {
case IntMap.Nil => Iterator.empty
case _ => new IntMapValueIterator(this)
}
/**
* Loop over the values of the map. The same as `values.foreach(f)`, but may
* be more efficient.
*
* @param f The loop body
*/
final def foreachValue(f: T => Unit): Unit = this match {
case IntMap.Bin(_, _, left, right) => { left.foreachValue(f); right.foreachValue(f) }
case IntMap.Tip(_, value) => f(value)
case IntMap.Nil =>
}
override def stringPrefix = "IntMap"
override def isEmpty = this == IntMap.Nil
override def filter(f: ((Int, T)) => Boolean): IntMap[T] = this match {
case IntMap.Bin(prefix, mask, left, right) => {
val (newleft, newright) = (left.filter(f), right.filter(f))
if ((left eq newleft) && (right eq newright)) this
else bin(prefix, mask, newleft, newright)
}
case IntMap.Tip(key, value) =>
if (f((key, value))) this
else IntMap.Nil
case IntMap.Nil => IntMap.Nil
}
def transform[S](f: (Int, T) => S): IntMap[S] = this match {
case [email protected](prefix, mask, left, right) => b.bin(left.transform(f), right.transform(f))
case [email protected](key, value) => t.withValue(f(key, value))
case IntMap.Nil => IntMap.Nil
}
final override def size: Int = this match {
case IntMap.Nil => 0
case IntMap.Tip(_, _) => 1
case IntMap.Bin(_, _, left, right) => left.size + right.size
}
final def get(key: Int): Option[T] = this match {
case IntMap.Bin(prefix, mask, left, right) => if (zero(key, mask)) left.get(key) else right.get(key)
case IntMap.Tip(key2, value) => if (key == key2) Some(value) else None
case IntMap.Nil => None
}
final override def getOrElse[S >: T](key: Int, default: => S): S = this match {
case IntMap.Nil => default
case IntMap.Tip(key2, value) => if (key == key2) value else default
case IntMap.Bin(prefix, mask, left, right) =>
if (zero(key, mask)) left.getOrElse(key, default) else right.getOrElse(key, default)
}
final override def apply(key: Int): T = this match {
case IntMap.Bin(prefix, mask, left, right) => if (zero(key, mask)) left(key) else right(key)
case IntMap.Tip(key2, value) => if (key == key2) value else sys.error("Key not found")
case IntMap.Nil => sys.error("key not found")
}
def + [S >: T] (kv: (Int, S)): IntMap[S] = updated(kv._1, kv._2)
override def updated[S >: T](key: Int, value: S): IntMap[S] = this match {
case IntMap.Bin(prefix, mask, left, right) =>
if (!hasMatch(key, prefix, mask)) join(key, IntMap.Tip(key, value), prefix, this)
else if (zero(key, mask)) IntMap.Bin(prefix, mask, left.updated(key, value), right)
else IntMap.Bin(prefix, mask, left, right.updated(key, value))
case IntMap.Tip(key2, value2) =>
if (key == key2) IntMap.Tip(key, value)
else join(key, IntMap.Tip(key, value), key2, this)
case IntMap.Nil => IntMap.Tip(key, value)
}
/**
* Updates the map, using the provided function to resolve conflicts if the key is already present.
*
* Equivalent to:
* {{{
* this.get(key) match {
* case None => this.update(key, value)
* case Some(oldvalue) => this.update(key, f(oldvalue, value)
* }
* }}}
*
* @tparam S The supertype of values in this `LongMap`.
* @param key The key to update
* @param value The value to use if there is no conflict
* @param f The function used to resolve conflicts.
* @return The updated map.
*/
def updateWith[S >: T](key: Int, value: S, f: (T, S) => S): IntMap[S] = this match {
case IntMap.Bin(prefix, mask, left, right) =>
if (!hasMatch(key, prefix, mask)) join(key, IntMap.Tip(key, value), prefix, this)
else if (zero(key, mask)) IntMap.Bin(prefix, mask, left.updateWith(key, value, f), right)
else IntMap.Bin(prefix, mask, left, right.updateWith(key, value, f))
case IntMap.Tip(key2, value2) =>
if (key == key2) IntMap.Tip(key, f(value2, value))
else join(key, IntMap.Tip(key, value), key2, this)
case IntMap.Nil => IntMap.Tip(key, value)
}
def - (key: Int): IntMap[T] = this match {
case IntMap.Bin(prefix, mask, left, right) =>
if (!hasMatch(key, prefix, mask)) this
else if (zero(key, mask)) bin(prefix, mask, left - key, right)
else bin(prefix, mask, left, right - key)
case IntMap.Tip(key2, _) =>
if (key == key2) IntMap.Nil
else this
case IntMap.Nil => IntMap.Nil
}
/**
* A combined transform and filter function. Returns an `IntMap` such that
* for each `(key, value)` mapping in this map, if `f(key, value) == None`
* the map contains no mapping for key, and if `f(key, value)`.
*
* @tparam S The type of the values in the resulting `LongMap`.
* @param f The transforming function.
* @return The modified map.
*/
def modifyOrRemove[S](f: (Int, T) => Option[S]): IntMap[S] = this match {
case IntMap.Bin(prefix, mask, left, right) =>
val newleft = left.modifyOrRemove(f)
val newright = right.modifyOrRemove(f)
if ((left eq newleft) && (right eq newright)) this.asInstanceOf[IntMap[S]]
else bin(prefix, mask, newleft, newright)
case IntMap.Tip(key, value) => f(key, value) match {
case None =>
IntMap.Nil
case Some(value2) =>
//hack to preserve sharing
if (value.asInstanceOf[AnyRef] eq value2.asInstanceOf[AnyRef]) this.asInstanceOf[IntMap[S]]
else IntMap.Tip(key, value2)
}
case IntMap.Nil =>
IntMap.Nil
}
/**
* Forms a union map with that map, using the combining function to resolve conflicts.
*
* @tparam S The type of values in `that`, a supertype of values in `this`.
* @param that The map to form a union with.
* @param f The function used to resolve conflicts between two mappings.
* @return Union of `this` and `that`, with identical key conflicts resolved using the function `f`.
*/
def unionWith[S >: T](that: IntMap[S], f: (Int, S, S) => S): IntMap[S] = (this, that) match{
case (IntMap.Bin(p1, m1, l1, r1), that@(IntMap.Bin(p2, m2, l2, r2))) =>
if (shorter(m1, m2)) {
if (!hasMatch(p2, p1, m1)) join[S](p1, this, p2, that) // TODO: remove [S] when scala/bug#5548 is fixed
else if (zero(p2, m1)) IntMap.Bin(p1, m1, l1.unionWith(that, f), r1)
else IntMap.Bin(p1, m1, l1, r1.unionWith(that, f))
} else if (shorter(m2, m1)){
if (!hasMatch(p1, p2, m2)) join[S](p1, this, p2, that) // TODO: remove [S] when scala/bug#5548 is fixed
else if (zero(p1, m2)) IntMap.Bin(p2, m2, this.unionWith(l2, f), r2)
else IntMap.Bin(p2, m2, l2, this.unionWith(r2, f))
}
else {
if (p1 == p2) IntMap.Bin(p1, m1, l1.unionWith(l2,f), r1.unionWith(r2, f))
else join[S](p1, this, p2, that) // TODO: remove [S] when scala/bug#5548 is fixed
}
case (IntMap.Tip(key, value), x) => x.updateWith[S](key, value, (x, y) => f(key, y, x))
case (x, IntMap.Tip(key, value)) => x.updateWith[S](key, value, (x, y) => f(key, x, y))
case (IntMap.Nil, x) => x
case (x, IntMap.Nil) => x
}
/**
* Forms the intersection of these two maps with a combining function. The
* resulting map is a map that has only keys present in both maps and has
* values produced from the original mappings by combining them with `f`.
*
* @tparam S The type of values in `that`.
* @tparam R The type of values in the resulting `LongMap`.
* @param that The map to intersect with.
* @param f The combining function.
* @return Intersection of `this` and `that`, with values for identical keys produced by function `f`.
*/
def intersectionWith[S, R](that: IntMap[S], f: (Int, T, S) => R): IntMap[R] = (this, that) match {
case (IntMap.Bin(p1, m1, l1, r1), [email protected](p2, m2, l2, r2)) =>
if (shorter(m1, m2)) {
if (!hasMatch(p2, p1, m1)) IntMap.Nil
else if (zero(p2, m1)) l1.intersectionWith(that, f)
else r1.intersectionWith(that, f)
} else if (m1 == m2) bin(p1, m1, l1.intersectionWith(l2, f), r1.intersectionWith(r2, f))
else {
if (!hasMatch(p1, p2, m2)) IntMap.Nil
else if (zero(p1, m2)) this.intersectionWith(l2, f)
else this.intersectionWith(r2, f)
}
case (IntMap.Tip(key, value), that) => that.get(key) match {
case None => IntMap.Nil
case Some(value2) => IntMap.Tip(key, f(key, value, value2))
}
case (_, IntMap.Tip(key, value)) => this.get(key) match {
case None => IntMap.Nil
case Some(value2) => IntMap.Tip(key, f(key, value2, value))
}
case (_, _) => IntMap.Nil
}
/**
* Left biased intersection. Returns the map that has all the same mappings
* as this but only for keys which are present in the other map.
*
* @tparam R The type of values in `that`.
* @param that The map to intersect with.
* @return A map with all the keys both in `this` and `that`, mapped to corresponding values from `this`.
*/
def intersection[R](that: IntMap[R]): IntMap[T] =
this.intersectionWith(that, (key: Int, value: T, value2: R) => value)
def ++[S >: T](that: IntMap[S]) =
this.unionWith[S](that, (key, x, y) => y)
/**
* The entry with the lowest key value considered in unsigned order.
*/
@tailrec
final def firstKey: Int = this match {
case Bin(_, _, l, r) => l.firstKey
case Tip(k, v) => k
case IntMap.Nil => sys.error("Empty set")
}
/**
* The entry with the highest key value considered in unsigned order.
*/
@tailrec
final def lastKey: Int = this match {
case Bin(_, _, l, r) => r.lastKey
case Tip(k, v) => k
case IntMap.Nil => sys.error("Empty set")
}
}