| // 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. |
| |
| #ifndef V8_ELEMENTS_H_ |
| #define V8_ELEMENTS_H_ |
| |
| #include "src/elements-kind.h" |
| #include "src/heap/heap.h" |
| #include "src/isolate.h" |
| #include "src/objects.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| // Abstract base class for handles that can operate on objects with differing |
| // ElementsKinds. |
| class ElementsAccessor { |
| public: |
| explicit ElementsAccessor(const char* name) : name_(name) { } |
| virtual ~ElementsAccessor() { } |
| |
| virtual ElementsKind kind() const = 0; |
| const char* name() const { return name_; } |
| |
| // Checks the elements of an object for consistency, asserting when a problem |
| // is found. |
| virtual void Validate(Handle<JSObject> obj) = 0; |
| |
| // Returns true if a holder contains an element with the specified key |
| // without iterating up the prototype chain. The caller can optionally pass |
| // in the backing store to use for the check, which must be compatible with |
| // the ElementsKind of the ElementsAccessor. If backing_store is NULL, the |
| // holder->elements() is used as the backing store. |
| virtual bool HasElement( |
| Handle<Object> receiver, |
| Handle<JSObject> holder, |
| uint32_t key, |
| Handle<FixedArrayBase> backing_store) = 0; |
| |
| inline bool HasElement( |
| Handle<Object> receiver, |
| Handle<JSObject> holder, |
| uint32_t key) { |
| return HasElement(receiver, holder, key, handle(holder->elements())); |
| } |
| |
| // Returns the element with the specified key or undefined if there is no such |
| // element. This method doesn't iterate up the prototype chain. The caller |
| // can optionally pass in the backing store to use for the check, which must |
| // be compatible with the ElementsKind of the ElementsAccessor. If |
| // backing_store is NULL, the holder->elements() is used as the backing store. |
| MUST_USE_RESULT virtual MaybeHandle<Object> Get( |
| Handle<Object> receiver, |
| Handle<JSObject> holder, |
| uint32_t key, |
| Handle<FixedArrayBase> backing_store) = 0; |
| |
| MUST_USE_RESULT inline MaybeHandle<Object> Get( |
| Handle<Object> receiver, |
| Handle<JSObject> holder, |
| uint32_t key) { |
| return Get(receiver, holder, key, handle(holder->elements())); |
| } |
| |
| // Returns an element's attributes, or ABSENT if there is no such |
| // element. This method doesn't iterate up the prototype chain. The caller |
| // can optionally pass in the backing store to use for the check, which must |
| // be compatible with the ElementsKind of the ElementsAccessor. If |
| // backing_store is NULL, the holder->elements() is used as the backing store. |
| MUST_USE_RESULT virtual PropertyAttributes GetAttributes( |
| Handle<Object> receiver, |
| Handle<JSObject> holder, |
| uint32_t key, |
| Handle<FixedArrayBase> backing_store) = 0; |
| |
| MUST_USE_RESULT inline PropertyAttributes GetAttributes( |
| Handle<Object> receiver, |
| Handle<JSObject> holder, |
| uint32_t key) { |
| return GetAttributes(receiver, holder, key, handle(holder->elements())); |
| } |
| |
| // Returns an element's accessors, or NULL if the element does not exist or |
| // is plain. This method doesn't iterate up the prototype chain. The caller |
| // can optionally pass in the backing store to use for the check, which must |
| // be compatible with the ElementsKind of the ElementsAccessor. If |
| // backing_store is NULL, the holder->elements() is used as the backing store. |
| MUST_USE_RESULT virtual MaybeHandle<AccessorPair> GetAccessorPair( |
| Handle<Object> receiver, |
| Handle<JSObject> holder, |
| uint32_t key, |
| Handle<FixedArrayBase> backing_store) = 0; |
| |
| MUST_USE_RESULT inline MaybeHandle<AccessorPair> GetAccessorPair( |
| Handle<Object> receiver, |
| Handle<JSObject> holder, |
| uint32_t key) { |
| return GetAccessorPair(receiver, holder, key, handle(holder->elements())); |
| } |
| |
| // Modifies the length data property as specified for JSArrays and resizes the |
| // underlying backing store accordingly. The method honors the semantics of |
| // changing array sizes as defined in EcmaScript 5.1 15.4.5.2, i.e. array that |
| // have non-deletable elements can only be shrunk to the size of highest |
| // element that is non-deletable. |
| MUST_USE_RESULT virtual MaybeHandle<Object> SetLength( |
| Handle<JSArray> holder, |
| Handle<Object> new_length) = 0; |
| |
| // Modifies both the length and capacity of a JSArray, resizing the underlying |
| // backing store as necessary. This method does NOT honor the semantics of |
| // EcmaScript 5.1 15.4.5.2, arrays can be shrunk beyond non-deletable |
| // elements. This method should only be called for array expansion OR by |
| // runtime JavaScript code that use InternalArrays and don't care about |
| // EcmaScript 5.1 semantics. |
| virtual void SetCapacityAndLength( |
| Handle<JSArray> array, |
| int capacity, |
| int length) = 0; |
| |
| // Deletes an element in an object, returning a new elements backing store. |
| MUST_USE_RESULT virtual MaybeHandle<Object> Delete( |
| Handle<JSObject> holder, |
| uint32_t key, |
| JSReceiver::DeleteMode mode) = 0; |
| |
| // If kCopyToEnd is specified as the copy_size to CopyElements, it copies all |
| // of elements from source after source_start to the destination array. |
| static const int kCopyToEnd = -1; |
| // If kCopyToEndAndInitializeToHole is specified as the copy_size to |
| // CopyElements, it copies all of elements from source after source_start to |
| // destination array, padding any remaining uninitialized elements in the |
| // destination array with the hole. |
| static const int kCopyToEndAndInitializeToHole = -2; |
| |
| // Copy elements from one backing store to another. Typically, callers specify |
| // the source JSObject or JSArray in source_holder. If the holder's backing |
| // store is available, it can be passed in source and source_holder is |
| // ignored. |
| virtual void CopyElements( |
| Handle<FixedArrayBase> source, |
| uint32_t source_start, |
| ElementsKind source_kind, |
| Handle<FixedArrayBase> destination, |
| uint32_t destination_start, |
| int copy_size) = 0; |
| |
| // TODO(ishell): Keeping |source_holder| parameter in a non-handlified form |
| // helps avoiding ArrayConcat() builtin performance degradation. |
| // Revisit this later. |
| virtual void CopyElements( |
| JSObject* source_holder, |
| uint32_t source_start, |
| ElementsKind source_kind, |
| Handle<FixedArrayBase> destination, |
| uint32_t destination_start, |
| int copy_size) = 0; |
| |
| inline void CopyElements( |
| Handle<JSObject> from_holder, |
| Handle<FixedArrayBase> to, |
| ElementsKind from_kind) { |
| CopyElements( |
| *from_holder, 0, from_kind, to, 0, kCopyToEndAndInitializeToHole); |
| } |
| |
| MUST_USE_RESULT virtual MaybeHandle<FixedArray> AddElementsToFixedArray( |
| Handle<Object> receiver, |
| Handle<JSObject> holder, |
| Handle<FixedArray> to, |
| Handle<FixedArrayBase> from) = 0; |
| |
| MUST_USE_RESULT inline MaybeHandle<FixedArray> AddElementsToFixedArray( |
| Handle<Object> receiver, |
| Handle<JSObject> holder, |
| Handle<FixedArray> to) { |
| return AddElementsToFixedArray( |
| receiver, holder, to, handle(holder->elements())); |
| } |
| |
| // Returns a shared ElementsAccessor for the specified ElementsKind. |
| static ElementsAccessor* ForKind(ElementsKind elements_kind) { |
| DCHECK(elements_kind < kElementsKindCount); |
| return elements_accessors_[elements_kind]; |
| } |
| |
| static ElementsAccessor* ForArray(Handle<FixedArrayBase> array); |
| |
| static void InitializeOncePerProcess(); |
| static void TearDown(); |
| |
| protected: |
| friend class SloppyArgumentsElementsAccessor; |
| |
| virtual uint32_t GetCapacity(Handle<FixedArrayBase> backing_store) = 0; |
| |
| // Element handlers distinguish between indexes and keys when they manipulate |
| // elements. Indexes refer to elements in terms of their location in the |
| // underlying storage's backing store representation, and are between 0 and |
| // GetCapacity. Keys refer to elements in terms of the value that would be |
| // specified 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(Handle<FixedArrayBase> backing_store, |
| uint32_t index) = 0; |
| |
| private: |
| static ElementsAccessor** elements_accessors_; |
| const char* name_; |
| |
| DISALLOW_COPY_AND_ASSIGN(ElementsAccessor); |
| }; |
| |
| void CheckArrayAbuse(Handle<JSObject> obj, const char* op, uint32_t key, |
| bool allow_appending = false); |
| |
| MUST_USE_RESULT MaybeHandle<Object> ArrayConstructInitializeElements( |
| Handle<JSArray> array, |
| Arguments* args); |
| |
| } } // namespace v8::internal |
| |
| #endif // V8_ELEMENTS_H_ |