akka.util.HashCode.scala Maven / Gradle / Ivy
/**
* Copyright (C) 2009-2012 Typesafe Inc.
*/
package akka.util
import java.lang.reflect.{ Array ⇒ JArray }
import java.lang.{ Float ⇒ JFloat, Double ⇒ JDouble }
/**
* Set of methods which allow easy implementation of hashCode.
*
* Example:
*
* 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
* }
*
*/
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
}