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Scala example source code file (HashSet.scala)

This example Scala source code file (HashSet.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

anyref, array, boolean, hashset, int, iterator, no, null, string, t

The HashSet.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2005-2013 LAMP/EPFL
 * @author  Martin Odersky
 */

package scala
package reflect
package internal.util

object HashSet {
  def apply[T >: Null <: AnyRef](initialCapacity: Int): HashSet[T] = this("No Label", initialCapacity)
  def apply[T >: Null <: AnyRef](label: String, initialCapacity: Int): HashSet[T] =
    new HashSet[T](label, initialCapacity)
}

class HashSet[T >: Null <: AnyRef](val label: String, initialCapacity: Int) extends Set[T] with scala.collection.generic.Clearable {
  private var used = 0
  private var table = new Array[AnyRef](initialCapacity)
  private def index(x: Int): Int = math.abs(x % table.length)

  def size: Int = used
  def clear() {
    used = 0
    table = new Array[AnyRef](initialCapacity)
  }

  def findEntryOrUpdate(x: T): T = {
    var h = index(x.##)
    var entry = table(h)
    while (entry ne null) {
      if (x == entry)
        return entry.asInstanceOf[T]

      h = index(h + 1)
      entry = table(h)
    }
    table(h) = x
    used += 1
    if (used > (table.length >> 2)) growTable()
    x
  }

  def findEntry(x: T): T = {
    var h = index(x.##)
    var entry = table(h)
    while ((entry ne null) && x != entry) {
      h = index(h + 1)
      entry = table(h)
    }
    entry.asInstanceOf[T]
  }

  def addEntry(x: T) {
    var h = index(x.##)
    var entry = table(h)
    while (entry ne null) {
      if (x == entry) return
      h = index(h + 1)
      entry = table(h)
    }
    table(h) = x
    used += 1
    if (used > (table.length >> 2)) growTable()
  }
  def addEntries(xs: TraversableOnce[T]) {
    xs foreach addEntry
  }

  def iterator = new Iterator[T] {
    private var i = 0
    def hasNext: Boolean = {
      while (i < table.length && (table(i) eq null)) i += 1
      i < table.length
    }
    def next(): T =
      if (hasNext) { i += 1; table(i - 1).asInstanceOf[T] }
      else null
  }

  private def addOldEntry(x: T) {
    var h = index(x.##)
    var entry = table(h)
    while (entry ne null) {
      h = index(h + 1)
      entry = table(h)
    }
    table(h) = x
  }

  private def growTable() {
    val oldtable = table
    val growthFactor =
      if (table.length <= initialCapacity) 8
      else if (table.length <= (initialCapacity * 8)) 4
      else 2

    table = new Array[AnyRef](table.length * growthFactor)
    var i = 0
    while (i < oldtable.length) {
      val entry = oldtable(i)
      if (entry ne null) addOldEntry(entry.asInstanceOf[T])
      i += 1
    }
  }
  override def toString() = "HashSet %s(%d / %d)".format(label, used, table.length)
}

Other Scala source code examples

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