Implement Object.is and Number.is[Finite,NaN] functions.

src/v8natives.js

Index: src/v8natives.js
diff --git a/src/v8natives.js b/src/v8natives.js
index 26724a24199d3384e224573a6bc50138071d4d75..f1e8084a53038dff8d8c33a888d2e1bf41311af4 100644
--- a/src/v8natives.js
+++ b/src/v8natives.js
@@ -1258,6 +1258,16 @@ function ObjectIsExtensible(obj) {
 }
 
 
+// Harmony egal.
+function ObjectIs(obj1, obj2) {
+  if (obj1 === obj2) {

[arv (Not doing code reviews), 2012/03/13 05:15:49]

Why don't we use the SameValue function?

http://code.google.com/codesearch#OAMlx_jo-ck/src/v8/src/runtime.js&exact_pac...

[Michael Starzinger, 2012/03/13 09:02:08]

Yes we could use that function, but I didn't care much about making it perfect
because this is only an intermediate step. And frankly I didn't remember we had
SameValue(), I only remembered it's native counterpart JSObject::SameValue(). If
you are interested in the full story, here is how I want to proceed with the
egal operator implementation:

1) Have our backends generate optimized code for [[SameValue]] and expose it via
an %_SameValue() intrinsic.
2) Use the same generated code to implement the "is" keyword behind --harmony
flag.
3) Once the --harmony flag is gone, switch Object.is() to actually use the "is"
keyword.

+    return (obj1 !== 0) || (1 / obj1 === 1 / obj2);
+  } else {
+    return (obj1 !== obj1) && (obj2 !== obj2);
+  }
+}
+
+
 %SetCode($Object, function(x) {
   if (%_IsConstructCall()) {
     if (x == null) return this;
@@ -1297,6 +1307,7 @@ function SetUpObject() {
     "getPrototypeOf", ObjectGetPrototypeOf,
     "getOwnPropertyDescriptor", ObjectGetOwnPropertyDescriptor,
     "getOwnPropertyNames", ObjectGetOwnPropertyNames,
+    "is", ObjectIs,
     "isExtensible", ObjectIsExtensible,
     "isFrozen", ObjectIsFrozen,
     "isSealed", ObjectIsSealed,
@@ -1461,6 +1472,18 @@ function NumberToPrecision(precision) {
 }
 
 
+// Harmony isFinite.
+function NumberIsFinite(number) {
+  return IS_NUMBER(number) && NUMBER_IS_FINITE(number);
+}
+
+
+// Harmony isNaN.
+function NumberIsNaN(number) {
+  return IS_NUMBER(number) && NUMBER_IS_NAN(number);
+}
+
+
 // ----------------------------------------------------------------------------
 
 function SetUpNumber() {
@@ -1505,6 +1528,10 @@ function SetUpNumber() {
     "toExponential", NumberToExponential,
     "toPrecision", NumberToPrecision
   ));
+  InstallFunctions($Number, DONT_ENUM, $Array(
+    "isFinite", NumberIsFinite,
+    "isNaN", NumberIsNaN
+  ));
 }
 
 SetUpNumber();