[Assorted-commits] SF.net SVN: assorted: [354] scala-commons/trunk/src/commons/Hash.scala

[<yan...@us...>]

Revision: 354
          http://assorted.svn.sourceforge.net/assorted/?rev=354&view=rev
Author:   yangzhang
Date:     2008-02-10 10:45:24 -0800 (Sun, 10 Feb 2008)

Log Message:
-----------
added hash functions

Added Paths:
-----------
    scala-commons/trunk/src/commons/Hash.scala

Added: scala-commons/trunk/src/commons/Hash.scala
===================================================================
--- scala-commons/trunk/src/commons/Hash.scala	                        (rev 0)
+++ scala-commons/trunk/src/commons/Hash.scala	2008-02-10 18:45:24 UTC (rev 354)
@@ -0,0 +1,33 @@
+package commons
+
+object Hash {
+
+  /**
+   * From libstdc++ 4.1 __stl_hash_string.
+   */
+  def hashStl(xs: Seq[Int]) = {
+    var h = 0
+    for (x <- xs) h = 5 * h + x
+    h
+  }
+
+  /**
+   * From Sun JDK6 String.hashCode.
+   */
+  def hashJava(xs: Seq[Int]) = {
+    var h = 0
+    for (x <- xs) h = 31 * h + x
+    h
+  }
+
+  /**
+   * From http://www.cse.yorku.ca/~oz/hash.html. Not sure if this is correct,
+   * since Int is signed.
+   */
+  def hashDjb2(xs: Seq[Int]) = {
+    var h = 5381
+    for (x <- xs) h = ((h << 5) + h) + x
+    h
+  }
+
+}


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