removes redundant hash implementation from BoxesRunTime.java

Author: dgruntz

src/library/scala/runtime/BoxesRunTime.java

@@ -203,67 +203,6 @@ private static boolean equalsNumChar(java.lang.Number xn, java.lang.Character yc
         }
     }
 
-    /** Hashcode algorithm is driven by the requirements imposed
-     *  by primitive equality semantics, namely that equal objects
-     *  have equal hashCodes.  The first priority are the integral/char
-     *  types, which already have the same hashCodes for the same
-     *  values except for Long.  So Long's hashCode is altered to
-     *  conform to Int's for all values in Int's range.
-     *
-     *  Float is problematic because it's far too small to hold
-     *  all the Ints, so for instance Int.MaxValue.toFloat claims
-     *  to be == to each of the largest 64 Ints.  There is no way
-     *  to preserve equals/hashCode alignment without compromising
-     *  the hashCode distribution, so Floats are only guaranteed
-     *  to have the same hashCode for whole Floats in the range
-     *  Short.MinValue to Short.MaxValue (2^16 total.)
-     *
-     *  Double has its hashCode altered to match the entire Int range,
-     *  but is not guaranteed beyond that.  (But could/should it be?
-     *  The hashCode is only 32 bits so this is a more tractable
-     *  issue than Float's, but it might be better simply to exclude it.)
-     *
-     *  Note: BigInt and BigDecimal, being arbitrary precision, could
-     *  be made consistent with all other types for the Int range, but
-     *  as yet have not.
-     *
-     *  Note: Among primitives, Float.NaN != Float.NaN, but the boxed
-     *  verisons are equal.  This still needs reconciliation.
-     */
-    public static int hashFromLong(java.lang.Long n) {
-        int iv = n.intValue();
-        if (iv == n.longValue()) return iv;
-        else return n.hashCode();
-    }
-    public static int hashFromDouble(java.lang.Double n) {
-        int iv = n.intValue();
-        double dv = n.doubleValue();
-        if (iv == dv) return iv;
-
-        long lv = n.longValue();
-        if (lv == dv) return java.lang.Long.valueOf(lv).hashCode();
-        else return n.hashCode();
-    }
-    public static int hashFromFloat(java.lang.Float n) {
-        int iv = n.intValue();
-        float fv = n.floatValue();
-        if (iv == fv) return iv;
-
-        long lv = n.longValue();
-        if (lv == fv) return java.lang.Long.valueOf(lv).hashCode();
-        else return n.hashCode();
-    }
-    public static int hashFromNumber(java.lang.Number n) {
-      if (n instanceof java.lang.Long) return hashFromLong((java.lang.Long)n);
-      else if (n instanceof java.lang.Double) return hashFromDouble((java.lang.Double)n);
-      else if (n instanceof java.lang.Float) return hashFromFloat((java.lang.Float)n);
-      else return n.hashCode();
-    }
-    public static int hashFromObject(Object a) {
-      if (a instanceof Number) return hashFromNumber((Number)a);
-      else return a.hashCode();
-    }
-
     private static int unboxCharOrInt(Object arg1, int code) {
       if (code == CHAR)
         return ((java.lang.Character) arg1).charValue();

src/library/scala/runtime/ScalaRunTime.scala

@@ -233,12 +233,39 @@ object ScalaRunTime {
   //
   // Note that these are the implementations called by ##, so they
   // must not call ## themselves.
+  //
+  // Hashcode algorithm is driven by the requirements imposed
+  // by primitive equality semantics, namely that equal objects
+  // have equal hashCodes.  The first priority are the integral/char
+  // types, which already have the same hashCodes for the same
+  // values except for Long.  So Long's hashCode is altered to
+  // conform to Int's for all values in Int's range.
+  //
+  // Float is problematic because it's far too small to hold
+  // all the Ints, so for instance Int.MaxValue.toFloat claims
+  // to be == to each of the largest 64 Ints.  There is no way
+  // to preserve equals/hashCode alignment without compromising
+  // the hashCode distribution, so Floats are only guaranteed
+  // to have the same hashCode for whole Floats in the range
+  // Short.MinValue to Short.MaxValue (2^16 total.)
+  //
+  // Double has its hashCode altered to match the entire Int range,
+  // but is not guaranteed beyond that.  (But could/should it be?
+  // The hashCode is only 32 bits so this is a more tractable
+  // issue than Float's, but it might be better simply to exclude it.)
+  //
+  // Note: BigInt and BigDecimal, being arbitrary precision, could
+  // be made consistent with all other types for the Int range, but
+  // as yet have not.
+  //
+  // Note: Among primitives, Float.NaN != Float.NaN, but the boxed
+  // verisons are equal.  This still needs reconciliation.
 
   @inline def hash(x: Any): Int = x match {
     case null                => 0
+    case x: Long             => hash(x)
     case x: Double           => hash(x)
     case x: Float            => hash(x)
-    case x: java.lang.Number => hash(x)
     case _                   => x.hashCode
   }
 
@@ -266,7 +293,6 @@ object ScalaRunTime {
     val high = (lv >>> 32).toInt
     low ^ (high + lowSign)
   }
-  @inline def hash(x: Number): Int  = runtime.BoxesRunTime.hashFromNumber(x)
 
   // The remaining overloads are here for completeness, but the compiler
   // inlines these definitions directly so they're not generally used.

test/files/run/hashCodeBoxesRunTime.scala renamed to test/files/run/hashCodeScalaRunTime.scala

@@ -1,23 +1,23 @@
-// This only tests direct access to the methods in BoxesRunTime,
+// This only tests direct access to the methods in ScalaRunTime,
 // not the whole scheme.
 object Test
 {
   import java.{ lang => jl }
-  import scala.runtime.BoxesRunTime.{ hashFromNumber, hashFromObject }
+  import scala.runtime.ScalaRunTime.{ hash }
 
   def allSame[T](xs: List[T]) = assert(xs.distinct.size == 1, "failed: " + xs)
 
   def mkNumbers(x: Int): List[Number] =
     List(x.toByte, x.toShort, x, x.toLong, x.toFloat, x.toDouble)
 
-  def testLDF(x: Long) = allSame(List[Number](x, x.toDouble, x.toFloat) map hashFromNumber)
+  def testLDF(x: Long) = allSame(List[Number](x, x.toDouble, x.toFloat) map hash)
 
   def main(args: Array[String]): Unit = {
     List(Byte.MinValue, -1, 0, 1, Byte.MaxValue) foreach { n => 
-      val hashes = mkNumbers(n) map hashFromNumber
+      val hashes = mkNumbers(n) map hash
       allSame(hashes)
       if (n >= 0) {
-        val charCode = hashFromObject(n.toChar: Character)
+        val charCode = hash(n.toChar: Character)
         assert(charCode == hashes.head)
       }
     }

test/files/run/hashhash.scala

@@ -9,7 +9,15 @@ object Test {
 
     val x = (BigInt(1) << 64).toDouble
     val y: Any = x
+    val f: Float = x.toFloat
+    val jn: java.lang.Number = x
+    val jf: java.lang.Float = x.toFloat
+    val jd: java.lang.Double = x
 
     assert(x.## == y.##, ((x, y)))
+    assert(x.## == f.##, ((x, f)))
+    assert(x.## == jn.##, ((x, jn)))
+    assert(x.## == jf.##, ((x, jf)))
+    assert(x.## == jd.##, ((x, jd)))
   }
 }