added Java compat API for defining up ActiveObjects

kernel/src/main/scala/HashCode.scala

@@ -0,0 +1,48 @@
+/**
+ * Copyright (C) 2009 Scalable Solutions.
+ */
+
+package com.scalablesolutions.akka.kernel
+
+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>
+ * 
+ * @author <a href="http://jonasboner.com">Jonas Bon&#233;r</a>
+ */
+object HashCode {
+  val SEED = 23
+
+  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))
+  def hash(seed: Int, anyRef: AnyRef): Int = {
+    var result = seed
+    if (anyRef == null) result = hash(result, 0)
+    else if (!isArray(anyRef)) result = hash(result, anyRef.hashCode())
+    else for (id <- 0 until JArray.getLength(anyRef)) result = hash(result, JArray.get(anyRef, id)) // is an array
+    result
+  }
+
+  private def firstTerm(seed: Int): Int = PRIME * seed
+  private def isArray(anyRef: AnyRef): Boolean = anyRef.getClass.isArray
+  private val PRIME = 37
+}
+