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/**
 * Copyright (C) 2009-2016 Lightbend 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 }




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