Implement String.hashCode.

dart/frog/leg/lib/js_helper.dart

Index: dart/frog/leg/lib/js_helper.dart
diff --git a/dart/frog/leg/lib/js_helper.dart b/dart/frog/leg/lib/js_helper.dart
index d730fa097f52c06284dd16c8f6629a26c3af305f..e106600d623d3c12bcb4bf97a2a331ba2719d29d 100644
--- a/dart/frog/leg/lib/js_helper.dart
+++ b/dart/frog/leg/lib/js_helper.dart
@@ -359,7 +359,7 @@ builtin$charCodeAt$1(var receiver, int index) {
     if (index is !num) throw new IllegalArgumentException(index);
     if (index < 0) throw new IndexOutOfRangeException(index);
     if (index >= receiver.length) throw new IndexOutOfRangeException(index);
-    return JS("string", @"$0.charCodeAt($1)", receiver, index);
+    return JS("int", @"$0.charCodeAt($1)", receiver, index);
   } else {
     return UNINTERCEPTED(receiver.charCodeAt(index));
   }
@@ -1181,16 +1181,36 @@ class MathNatives {
 }
 
 builtin$hashCode$0(receiver) {
+  if (receiver is String) return stringHashCodeUnchecked(receiver);
   if (receiver is num) return receiver & 0x1FFFFFFF;
-  if (receiver is String) {
-    throw 'String.hashCode is not implemented';
-  }
-  if (isJsArray(receiver)) {
-    throw 'List.hashCode is not implemented';
-  }
   return UNINTERCEPTED(receiver.hashCode());
 }
 
+/**
+ * This is the [Jenkins hash function][1], but always using XOR
+ * instead of addition to keep the hash value in 32bit. This was
+ * inspired by jmesserly's work in Frog. However, using XOR is 40%
+ * faster than the original version in Frog.
+ *
+ * Caveat: As long as String.hashCode isn't optimized, Frog will
+ * out-perform Leg because of the overhead of calling
+ * [builtin$hashCode$0].
+ *
+ * [1]: http://en.wikipedia.org/wiki/Jenkins_hash_function
+ */
+stringHashCodeUnchecked(string) {
+  var hash = 0;

[kasperl, 2012/02/28 09:37:08]

int hash?

[ahe, 2012/02/28 10:09:35]

Done.

+  var length = JS('int', @'$0.length', string);
+  for (var i = 0; i < length; i++) {

[kasperl, 2012/02/28 09:37:08]

int i?

[ahe, 2012/02/28 10:09:35]

Done.

+    hash ^= JS('int', @'$0.charCodeAt($1)', string, i);
+    hash ^= JS("int", @"$0 << $1", hash, 10);

[ngeoffray, 2012/02/28 10:13:25]

Cobnsistency -> use ' instead of "

[ahe, 2012/02/28 17:26:10]

Done.

+    hash ^= hash >> 6;
+  }
+  hash ^= JS("int", @"$0 << $1", hash, 3);

[ngeoffray, 2012/02/28 10:13:25]

ditto

[ahe, 2012/02/28 17:26:10]

Done.

+  hash ^= hash >> 11;
+  return 0x1fffffff & (hash ^ JS("int", @"$0 << $1", hash, 15));
+}
+
 // TODO(ahe): Dynamic may be overridden.
 builtin$get$dynamic(receiver) => receiver;