Encapsulate element handling into a class keyed on ElementsKind

src/objects.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 53 matching lines @@
 //       - ByteArray
 //       - ExternalArray
 //         - ExternalPixelArray
 //         - ExternalByteArray
 //         - ExternalUnsignedByteArray
 //         - ExternalShortArray
 //         - ExternalUnsignedShortArray
 //         - ExternalIntArray
 //         - ExternalUnsignedIntArray
 //         - ExternalFloatArray
 //       - FixedArray

[Lasse Reichstein, 2011/08/02 12:23:46]

I suddently remembered that this documentation is out-of-date now that there is
a FixedArrayBase. If possible, make it match reality :)

[danno, 2011/08/02 13:37:46]

Done.

 //         - DescriptorArray
 //         - HashTable
 //           - Dictionary
 //           - SymbolTable
 //           - CompilationCacheTable
 //           - CodeCacheHashTable
 //           - MapCache
 //         - Context
 //         - JSFunctionResultCache
 //         - SerializedScopeInfo
@@ skipping 538 matching lines @@
   inline bool name();                  \
   inline void set_##name(bool value);  \
 
 
 #define DECL_ACCESSORS(name, type)                                      \
   inline type* name();                                                  \
   inline void set_##name(type* value,                                   \
                          WriteBarrierMode mode = UPDATE_WRITE_BARRIER); \
 
 
+class ElementsHandler;
 class StringStream;
 class ObjectVisitor;
+class DictionaryElementsHandlerImpl;
 
 struct ValueInfo : public Malloced {
   ValueInfo() : type(FIRST_TYPE), ptr(NULL), str(NULL), number(0) { }
   InstanceType type;
   Object* ptr;
   const char* str;
   double number;
 };
 
 
@@ skipping 836 matching lines @@
   // writing to any element the array must be copied. Use
   // EnsureWritableFastElements in this case.
   //
   // In the slow mode the elements is either a NumberDictionary, an
   // ExternalArray, or a FixedArray parameter map for a (non-strict)
   // arguments object.
   DECL_ACCESSORS(elements, HeapObject)
   inline void initialize_elements();
   MUST_USE_RESULT inline MaybeObject* ResetElements();
   inline ElementsKind GetElementsKind();
+  inline ElementsHandler* GetElementsHandler();
   inline bool HasFastElements();
   inline bool HasFastDoubleElements();
   inline bool HasDictionaryElements();
   inline bool HasExternalPixelElements();
   inline bool HasExternalArrayElements();
   inline bool HasExternalByteElements();
   inline bool HasExternalUnsignedByteElements();
   inline bool HasExternalShortElements();
   inline bool HasExternalUnsignedShortElements();
   inline bool HasExternalIntElements();
@@ skipping 225 matching lines @@
   MUST_USE_RESULT MaybeObject* SetElement(uint32_t index,
                                           Object* value,
                                           StrictModeFlag strict_mode,
                                           bool check_prototype);
 
   // Returns the index'th element.
   // The undefined object if index is out of bounds.
   MaybeObject* GetElementWithReceiver(Object* receiver, uint32_t index);
   MaybeObject* GetElementWithInterceptor(Object* receiver, uint32_t index);
 
-  // Get external element value at index if there is one and undefined
-  // otherwise. Can return a failure if allocation of a heap number
-  // failed.
-  MaybeObject* GetExternalElement(uint32_t index);
-
   // Replace the elements' backing store with fast elements of the given
   // capacity.  Update the length for JSArrays.  Returns the new backing
   // store.
   MUST_USE_RESULT MaybeObject* SetFastElementsCapacityAndLength(int capacity,
                                                                 int length);
   MUST_USE_RESULT MaybeObject* SetFastDoubleElementsCapacityAndLength(
       int capacity,
       int length);
   MUST_USE_RESULT MaybeObject* SetSlowElements(Object* length);
 
@@ skipping 243 matching lines @@
   static const int kHeaderSize = kElementsOffset + kPointerSize;
 
   STATIC_CHECK(kHeaderSize == Internals::kJSObjectHeaderSize);
 
   class BodyDescriptor : public FlexibleBodyDescriptor<kPropertiesOffset> {
    public:
     static inline int SizeOf(Map* map, HeapObject* object);
   };
 
  private:
+  friend class DictionaryElementsHandlerImpl;
+
   MUST_USE_RESULT MaybeObject* GetElementWithCallback(Object* receiver,
                                                       Object* structure,
                                                       uint32_t index,
                                                       Object* holder);
   MaybeObject* SetElementWithCallback(Object* structure,
                                       uint32_t index,
                                       Object* value,
                                       JSObject* holder,
                                       StrictModeFlag strict_mode);
   MUST_USE_RESULT MaybeObject* SetElementWithInterceptor(
       uint32_t index,
       Object* value,
       StrictModeFlag strict_mode,
       bool check_prototype);
   MUST_USE_RESULT MaybeObject* SetElementWithoutInterceptor(
       uint32_t index,
       Object* value,
       StrictModeFlag strict_mode,
       bool check_prototype);
 
-  MaybeObject* GetElementPostInterceptor(Object* receiver, uint32_t index);
-
   MUST_USE_RESULT MaybeObject* DeletePropertyPostInterceptor(String* name,
                                                              DeleteMode mode);
   MUST_USE_RESULT MaybeObject* DeletePropertyWithInterceptor(String* name);
 
   MUST_USE_RESULT MaybeObject* DeleteElementPostInterceptor(uint32_t index,
                                                             DeleteMode mode);
   MUST_USE_RESULT MaybeObject* DeleteElementWithInterceptor(uint32_t index);
 
   MUST_USE_RESULT MaybeObject* DeleteFastElement(uint32_t index);
   MUST_USE_RESULT MaybeObject* DeleteDictionaryElement(uint32_t index,
@@ skipping 26 matching lines @@
       PropertyAttributes attributes);
 
   void LookupInDescriptor(String* name, LookupResult* result);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSObject);
 };
 
 
 // Common superclass for FixedArrays that allow implementations to share
 // common accessors and some code paths.
 class FixedArrayBase: public HeapObject {

[Lasse Reichstein, 2011/08/01 09:35:54]

Preferably this should be called FixedArray, as the generic superclass of all
fixed-size arrays, and the original FixedArray should be ObjectFixedArray.
I can see why it wasn't done, though, having done the same thing myself
elsewhere :)

[danno, 2011/08/02 13:37:46]

That's a reasonable observation, but I think I'll leave that for another CL :-)
On 2011/08/01 09:35:54, Lasse Reichstein wrote:

  public:
   // [length]: length of the array.
   inline int length();
   inline void set_length(int value);
 
   inline static FixedArrayBase* cast(Object* object);
 
   // Layout description.
   // Length is smi tagged when it is stored.
   static const int kLengthOffset = HeapObject::kHeaderSize;
   static const int kHeaderSize = kLengthOffset + kPointerSize;
 };
 
 class FixedDoubleArray;
 
 // FixedArray describes fixed-sized arrays with element type Object*.
 class FixedArray: public FixedArrayBase {
  public:
   // Setter and getter for elements.
   inline Object* get(int index);
   // Setter that uses write barrier.
   inline void set(int index, Object* value);
+  inline bool is_the_hole(int index);
 
   // Setter that doesn't need write barrier).
   inline void set(int index, Smi* value);
   // Setter with explicit barrier mode.
   inline void set(int index, Object* value, WriteBarrierMode mode);
 
   // Setters for frequently used oddballs located in old space.
   inline void set_undefined(int index);
   // TODO(isolates): duplicate.
   inline void set_undefined(Heap* heap, int index);
@@ skipping 85 matching lines @@
 
 
 // FixedDoubleArray describes fixed-sized arrays with element type double.
 class FixedDoubleArray: public FixedArrayBase {
  public:
   inline void Initialize(FixedArray* from);
   inline void Initialize(FixedDoubleArray* from);
   inline void Initialize(NumberDictionary* from);
 
   // Setter and getter for elements.
-  inline double get(int index);
+  inline double get_scalar(int index);
+  inline MaybeObject* get(int index);
   inline void set(int index, double value);
   inline void set_the_hole(int index);
 
   // Checking for the hole.
   inline bool is_the_hole(int index);
 
   // Garbage collection support.
   inline static int SizeFor(int length) {
     return kHeaderSize + length * kDoubleSize;
   }
@@ skipping 911 matching lines @@
 // The semantics of these arrays differ from CanvasPixelArray.
 // Out-of-range values passed to the setter are converted via a C
 // cast, not clamping. Out-of-range indices cause exceptions to be
 // raised rather than being silently ignored.
 class ExternalArray: public HeapObject {
  public:
   // [length]: length of the array.
   inline int length();
   inline void set_length(int value);
 
+  inline bool is_the_hole(int index) { return false; }
+
   // [external_pointer]: The pointer to the external memory area backing this
   // external array.
   DECL_ACCESSORS(external_pointer, void)  // Pointer to the data store.
 
   // Casting.
   static inline ExternalArray* cast(Object* obj);
 
   // Maximal acceptable length for an external array.
   static const int kMaxLength = 0x3fffffff;
 
@@ skipping 15 matching lines @@
 
 // http://www.whatwg.org/specs/web-apps/current-work/
 //                      multipage/the-canvas-element.html#canvaspixelarray
 // In particular, write access clamps the value written to 0 or 255 if the
 // value written is outside this range.
 class ExternalPixelArray: public ExternalArray {
  public:
   inline uint8_t* external_pixel_pointer();
 
   // Setter and getter.
-  inline uint8_t get(int index);
+  inline uint8_t get_scalar(int index);
+  inline MaybeObject* get(int index);
   inline void set(int index, uint8_t value);
 
   // This accessor applies the correct conversion from Smi, HeapNumber and
   // undefined and clamps the converted value between 0 and 255.
   Object* SetValue(uint32_t index, Object* value);
 
   // Casting.
   static inline ExternalPixelArray* cast(Object* obj);
 
 #ifdef OBJECT_PRINT
   inline void ExternalPixelArrayPrint() {
     ExternalPixelArrayPrint(stdout);
   }
   void ExternalPixelArrayPrint(FILE* out);
 #endif
 #ifdef DEBUG
   void ExternalPixelArrayVerify();
 #endif  // DEBUG
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalPixelArray);
 };
 
 
 class ExternalByteArray: public ExternalArray {
  public:
   // Setter and getter.
-  inline int8_t get(int index);
+  inline int8_t get_scalar(int index);
+  inline MaybeObject* get(int index);
   inline void set(int index, int8_t value);
 
   // This accessor applies the correct conversion from Smi, HeapNumber
   // and undefined.
   MaybeObject* SetValue(uint32_t index, Object* value);
 
   // Casting.
   static inline ExternalByteArray* cast(Object* obj);
 
 #ifdef OBJECT_PRINT
   inline void ExternalByteArrayPrint() {
     ExternalByteArrayPrint(stdout);
   }
   void ExternalByteArrayPrint(FILE* out);
 #endif
 #ifdef DEBUG
   void ExternalByteArrayVerify();
 #endif  // DEBUG
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalByteArray);
 };
 
 
 class ExternalUnsignedByteArray: public ExternalArray {
  public:
   // Setter and getter.
-  inline uint8_t get(int index);
+  inline uint8_t get_scalar(int index);
+  inline MaybeObject* get(int index);
   inline void set(int index, uint8_t value);
 
   // This accessor applies the correct conversion from Smi, HeapNumber
   // and undefined.
   MaybeObject* SetValue(uint32_t index, Object* value);
 
   // Casting.
   static inline ExternalUnsignedByteArray* cast(Object* obj);
 
 #ifdef OBJECT_PRINT
   inline void ExternalUnsignedByteArrayPrint() {
     ExternalUnsignedByteArrayPrint(stdout);
   }
   void ExternalUnsignedByteArrayPrint(FILE* out);
 #endif
 #ifdef DEBUG
   void ExternalUnsignedByteArrayVerify();
 #endif  // DEBUG
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalUnsignedByteArray);
 };
 
 
 class ExternalShortArray: public ExternalArray {
  public:
   // Setter and getter.
-  inline int16_t get(int index);
+  inline int16_t get_scalar(int index);
+  inline MaybeObject* get(int index);
   inline void set(int index, int16_t value);
 
   // This accessor applies the correct conversion from Smi, HeapNumber
   // and undefined.
   MaybeObject* SetValue(uint32_t index, Object* value);
 
   // Casting.
   static inline ExternalShortArray* cast(Object* obj);
 
 #ifdef OBJECT_PRINT
   inline void ExternalShortArrayPrint() {
     ExternalShortArrayPrint(stdout);
   }
   void ExternalShortArrayPrint(FILE* out);
 #endif
 #ifdef DEBUG
   void ExternalShortArrayVerify();
 #endif  // DEBUG
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalShortArray);
 };
 
 
 class ExternalUnsignedShortArray: public ExternalArray {
  public:
   // Setter and getter.
-  inline uint16_t get(int index);
+  inline uint16_t get_scalar(int index);
+  inline MaybeObject* get(int index);
   inline void set(int index, uint16_t value);
 
   // This accessor applies the correct conversion from Smi, HeapNumber
   // and undefined.
   MaybeObject* SetValue(uint32_t index, Object* value);
 
   // Casting.
   static inline ExternalUnsignedShortArray* cast(Object* obj);
 
 #ifdef OBJECT_PRINT
   inline void ExternalUnsignedShortArrayPrint() {
     ExternalUnsignedShortArrayPrint(stdout);
   }
   void ExternalUnsignedShortArrayPrint(FILE* out);
 #endif
 #ifdef DEBUG
   void ExternalUnsignedShortArrayVerify();
 #endif  // DEBUG
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalUnsignedShortArray);
 };
 
 
 class ExternalIntArray: public ExternalArray {
  public:
   // Setter and getter.
-  inline int32_t get(int index);
+  inline int32_t get_scalar(int index);
+  inline MaybeObject* get(int index);
   inline void set(int index, int32_t value);
 
   // This accessor applies the correct conversion from Smi, HeapNumber
   // and undefined.
   MaybeObject* SetValue(uint32_t index, Object* value);
 
   // Casting.
   static inline ExternalIntArray* cast(Object* obj);
 
 #ifdef OBJECT_PRINT
   inline void ExternalIntArrayPrint() {
     ExternalIntArrayPrint(stdout);
   }
   void ExternalIntArrayPrint(FILE* out);
 #endif
 #ifdef DEBUG
   void ExternalIntArrayVerify();
 #endif  // DEBUG
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalIntArray);
 };
 
 
 class ExternalUnsignedIntArray: public ExternalArray {
  public:
   // Setter and getter.
-  inline uint32_t get(int index);
+  inline uint32_t get_scalar(int index);
+  inline MaybeObject* get(int index);
   inline void set(int index, uint32_t value);
 
   // This accessor applies the correct conversion from Smi, HeapNumber
   // and undefined.
   MaybeObject* SetValue(uint32_t index, Object* value);
 
   // Casting.
   static inline ExternalUnsignedIntArray* cast(Object* obj);
 
 #ifdef OBJECT_PRINT
   inline void ExternalUnsignedIntArrayPrint() {
     ExternalUnsignedIntArrayPrint(stdout);
   }
   void ExternalUnsignedIntArrayPrint(FILE* out);
 #endif
 #ifdef DEBUG
   void ExternalUnsignedIntArrayVerify();
 #endif  // DEBUG
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalUnsignedIntArray);
 };
 
 
 class ExternalFloatArray: public ExternalArray {
  public:
   // Setter and getter.
-  inline float get(int index);
+  inline float get_scalar(int index);
+  inline MaybeObject* get(int index);
   inline void set(int index, float value);
 
   // This accessor applies the correct conversion from Smi, HeapNumber
   // and undefined.
   MaybeObject* SetValue(uint32_t index, Object* value);
 
   // Casting.
   static inline ExternalFloatArray* cast(Object* obj);
 
 #ifdef OBJECT_PRINT
   inline void ExternalFloatArrayPrint() {
     ExternalFloatArrayPrint(stdout);
   }
   void ExternalFloatArrayPrint(FILE* out);
 #endif
 #ifdef DEBUG
   void ExternalFloatArrayVerify();
 #endif  // DEBUG
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(ExternalFloatArray);
 };
 
 
 class ExternalDoubleArray: public ExternalArray {
  public:
   // Setter and getter.
-  inline double get(int index);
+  inline double get_scalar(int index);
+  inline MaybeObject* get(int index);
   inline void set(int index, double value);
 
   // This accessor applies the correct conversion from Smi, HeapNumber
   // and undefined.
   MaybeObject* SetValue(uint32_t index, Object* value);
 
   // Casting.
   static inline ExternalDoubleArray* cast(Object* obj);
 
 #ifdef OBJECT_PRINT
@@ skipping 3854 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_