Implement UnionOfKeys for NonStrictArguments

src/elements.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 23 matching lines @@
 namespace internal {
 
 // Abstract base class for handles that can operate on objects with differing
 // ElementsKinds.
 class ElementsAccessor {
  public:
   ElementsAccessor() { }
   virtual ~ElementsAccessor() { }
   virtual MaybeObject* GetWithReceiver(JSObject* obj,
                                        Object* receiver,
-                                       uint32_t index) = 0;
+                                       uint32_t key) = 0;
 
   virtual MaybeObject* Delete(JSObject* obj,
-                              uint32_t index,
+                              uint32_t key,
                               JSReceiver::DeleteMode mode) = 0;
 
   virtual MaybeObject* AddElementsToFixedArray(FixedArrayBase* from,
                                                FixedArray* to) = 0;
 
   // Returns a shared ElementsAccessor for the specified ElementsKind.
   static ElementsAccessor* ForKind(JSObject::ElementsKind elements_kind) {
     ASSERT(elements_kind < JSObject::kElementsKindCount);
     return elements_accessors_[elements_kind];
   }
 
+  static ElementsAccessor* ForArray(FixedArrayBase* array);
+
   static void InitializeOncePerProcess();
 
+ protected:
+  friend class NonStrictArgumentsElementsAccessor;
+
+  // TODO(danno): GetElement should be merged with GetWithReceiver.
+  virtual MaybeObject* GetElement(FixedArrayBase* backing_store,
+                                  uint32_t key) = 0;
+
+  virtual uint32_t GetCapacity(FixedArrayBase* backing_store) = 0;
+
+  virtual bool HasElementAtIndex(FixedArrayBase* backing_store,
+                                 uint32_t index) = 0;
+
+  // Element handlers distinguish between indexes and keys when the manipulate
+  // elements.  Indexes refer to elements in terms of their location in the
+  // underlying storage's backing store representation, and are between 0
+  // GetCapacity.  Keys refer to elements in terms of the value that would be
+  // specific in JavaScript to access the element. In most implementations, keys
+  // are equivalent to indexes, and GetKeyForIndex returns the same value it is
+  // passed. In the NumberDictionary ElementsAccessor, GetKeyForIndex maps the
+  // index to a key using the KeyAt method on the NumberDictionary.
+  virtual uint32_t GetKeyForIndex(FixedArrayBase* backing_store,
+                                  uint32_t index) = 0;
+
  private:
   static ElementsAccessor** elements_accessors_;
 
   DISALLOW_COPY_AND_ASSIGN(ElementsAccessor);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ELEMENTS_H_