Expose Value::IsArgumentsObject in V8 API.

R=yangguo@chromium.org, svenpanne@chromium.org, yangguo

Review URL: https://codereview.chromium.org/460333002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23105 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -1423,6 +1423,11 @@ class V8_EXPORT Value : public Data {
    */
   bool IsDate() const;
 
+  /**
+   * Returns true if this value is an Arguments object.
+   */
+  bool IsArgumentsObject() const;
+
   /**
    * Returns true if this value is a Boolean object.
    */

src/api.cc

@@ -2383,6 +2383,14 @@ bool Value::IsNumber() const {
 }
 
 
+bool Value::IsArgumentsObject() const {
+  i::Handle<i::Object> obj = Utils::OpenHandle(this);
+  if (!obj->IsHeapObject()) return false;
+  i::Isolate* isolate = i::HeapObject::cast(*obj)->GetIsolate();
+  return obj->HasSpecificClassOf(isolate->heap()->Arguments_string());
+}
+
+
 bool Value::IsBoolean() const {
   return Utils::OpenHandle(this)->IsBoolean();
 }

test/cctest/test-api.cc

@@ -1541,6 +1541,19 @@ THREADED_TEST(IsNativeError) {
 }
 
 
+THREADED_TEST(ArgumentsObject) {
+  LocalContext env;
+  v8::HandleScope scope(env->GetIsolate());
+  v8::Handle<Value> arguments_object =
+      CompileRun("var out = 0; (function(){ out = arguments; })(1,2,3); out;");
+  CHECK(arguments_object->IsArgumentsObject());
+  v8::Handle<Value> array = CompileRun("[1,2,3]");
+  CHECK(!array->IsArgumentsObject());
+  v8::Handle<Value> object = CompileRun("{a:42}");
+  CHECK(!object->IsArgumentsObject());
+}
+
+
 THREADED_TEST(StringObject) {
   LocalContext env;
   v8::HandleScope scope(env->GetIsolate());