Akka/Scala example source code file (HashCode.scala)

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

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

Akka tags/keywords

akka, anyref, boolean, byte, char, double, float, int, long, prime, seed, util

The HashCode.scala Akka example source code

/**
 * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 */

package akka.util

import java.lang.reflect.{ Array ⇒ JArray }
import java.lang.{ Float ⇒ JFloat, Double ⇒ JDouble }

/**
 * Set of methods which allow easy implementation of <code>hashCode</code>.
 *
 * Example:
 * <pre>
 *  override def hashCode: Int = {
 *    var result = HashCode.SEED
 *    //collect the contributions of various fields
 *    result = HashCode.hash(result, fPrimitive)
 *    result = HashCode.hash(result, fObject)
 *    result = HashCode.hash(result, fArray)
 *    result
 *  }
 * </pre>
 */
object HashCode {
  val SEED = 23

  def hash(seed: Int, any: Any): Int = any match {
    case value: Boolean ⇒ hash(seed, value)
    case value: Char    ⇒ hash(seed, value)
    case value: Short   ⇒ hash(seed, value)
    case value: Int     ⇒ hash(seed, value)
    case value: Long    ⇒ hash(seed, value)
    case value: Float   ⇒ hash(seed, value)
    case value: Double  ⇒ hash(seed, value)
    case value: Byte    ⇒ hash(seed, value)
    case value: AnyRef ⇒
      var result = seed
      if (value eq null) result = hash(result, 0)
      else if (!isArray(value)) result = hash(result, value.hashCode())
      else for (id ← 0 until JArray.getLength(value)) result = hash(result, JArray.get(value, id)) // is an array
      result
  }
  def hash(seed: Int, value: Boolean): Int = firstTerm(seed) + (if (value) 1 else 0)
  def hash(seed: Int, value: Char): Int = firstTerm(seed) + value.asInstanceOf[Int]
  def hash(seed: Int, value: Int): Int = firstTerm(seed) + value
  def hash(seed: Int, value: Long): Int = firstTerm(seed) + (value ^ (value >>> 32)).asInstanceOf[Int]
  def hash(seed: Int, value: Float): Int = hash(seed, JFloat.floatToIntBits(value))
  def hash(seed: Int, value: Double): Int = hash(seed, JDouble.doubleToLongBits(value))

  private def firstTerm(seed: Int): Int = PRIME * seed
  private def isArray(anyRef: AnyRef): Boolean = anyRef.getClass.isArray
  private val PRIME = 37
}