Implement a native identical function in the VM.

runtime/lib/identical.cc

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "vm/bootstrap_natives.h"
+
+namespace dart {
+
+DEFINE_NATIVE_ENTRY(Identical_comparison, 2) {
+  GET_NON_NULL_NATIVE_ARGUMENT(
+     Instance, a, arguments->NativeArgAt(0));

[srdjan, 2012/12/17 22:10:19]

Null can be an argument: identical(null, 2). Please add test.

[Max Heinritz (Google), 2012/12/17 23:27:57]

Done.

+  GET_NON_NULL_NATIVE_ARGUMENT(
+     Instance, b, arguments->NativeArgAt(1));
+  // If objects are both numbers of the same type, compare values.

[srdjan, 2012/12/17 22:10:19]

Suggestion:

if (a.raw() == b.raw()) return Bool::True();
if (a.IsInteger() && b.IsInteger()) {
  return Bool::Get(a.Equals(b));
}
if (a.IsDouble() && b.IsDouble()) {
  if (a.Equals(b)) return Bool::True();
  // Check for NaN
  Double a_double = Double::Cast(a);
  Double b_double = Double::Cast(b);
  if (is_nan(a_double.value()) && is_nan(a_double.value())) {
    return Bool::True();
  }
}
return Bool::False;

[Max Heinritz (Google), 2012/12/17 23:27:57]

Done.

+  if ((a.IsSmi() && b.IsSmi()) ||
+      (a.IsMint() && b.IsMint()) ||
+      (a.IsDouble() && b.IsDouble()) ||
+      (a.IsBigint() && b.IsBigint())) {
+    return Bool::Get(a.Equals(b));
+  }
+  // If the objects are not numbers, compare references.
+  return Bool::Get(a.raw() == b.raw());
+}
+
+
+}  // namespace dart