Expose Value::IsArgumentsObject in V8 API.

src/api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/api.h"
 
 #include <string.h>  // For memcpy, strlen.
 #ifdef V8_USE_ADDRESS_SANITIZER
 #include <sanitizer/asan_interface.h>
 #endif  // V8_USE_ADDRESS_SANITIZER
@@ skipping 2365 matching lines @@
 bool Value::IsObject() const {
   return Utils::OpenHandle(this)->IsJSObject();
 }
 
 
 bool Value::IsNumber() const {
   return Utils::OpenHandle(this)->IsNumber();
 }
 
 
+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());

[Yang, 2014/08/12 10:53:46]

I don't think this is fool-proof. You could always just create a constructor
named "Arguments".

How about checking against the sloppy_arguments_map or the strict_arguments_map?

And I noticed how Heap::Arguments_string is not even used. We could remove that
root entry.

+}
+
+
 bool Value::IsBoolean() const {
   return Utils::OpenHandle(this)->IsBoolean();
 }
 
 
 bool Value::IsExternal() const {
   return Utils::OpenHandle(this)->IsExternal();
 }
 
 
@@ skipping 893 matching lines @@
 
   // Native implementation of Object.prototype.toString (v8natives.js):
   //   var c = %_ClassOf(this);
   //   if (c === 'Arguments') c  = 'Object';
   //   return "[object " + c + "]";
 
   if (!name->IsString()) {
     return v8::String::NewFromUtf8(isolate, "[object ]");
   } else {
     i::Handle<i::String> class_name = i::Handle<i::String>::cast(name);
     if (class_name->IsOneByteEqualTo(STATIC_ASCII_VECTOR("Arguments"))) {

[aandrey, 2014/08/12 11:17:16]

I think Arguments_string() should also be used here, as well as in
bootstrapper.cc line 1184.

       return v8::String::NewFromUtf8(isolate, "[object Object]");
     } else {
       const char* prefix = "[object ";
       Local<String> str = Utils::ToLocal(class_name);
       const char* postfix = "]";
 
       int prefix_len = i::StrLength(prefix);
       int str_len = str->Utf8Length();
       int postfix_len = i::StrLength(postfix);
 
@@ skipping 4323 matching lines @@
   Isolate* isolate = reinterpret_cast<Isolate*>(info.GetIsolate());
   Address callback_address =
       reinterpret_cast<Address>(reinterpret_cast<intptr_t>(callback));
   VMState<EXTERNAL> state(isolate);
   ExternalCallbackScope call_scope(isolate, callback_address);
   callback(info);
 }
 
 
 } }  // namespace v8::internal