text: // 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_OBJECTS_ELEMENTS_H_
  #define V8_OBJECTS_ELEMENTS_H_
  
  #include "src/objects/elements-kind.h"
  #include "src/objects/keys.h"
  #include "src/objects/objects.h"
  
  namespace v8 {
  namespace internal {
  
  class JSTypedArray;
  
  // Abstract base class for handles that can operate on objects with differing
  // ElementsKinds.
  class ElementsAccessor {
   public:
    ElementsAccessor() = default;
    virtual ~ElementsAccessor() = default;
  
    // Returns a shared ElementsAccessor for the specified ElementsKind.
    static ElementsAccessor* ForKind(ElementsKind elements_kind) {
      DCHECK_LT(static_cast<int>(elements_kind), kElementsKindCount);
      return elements_accessors_[elements_kind];
    }
  
    // Checks the elements of an object for consistency, asserting when a problem
    // is found.
    virtual void Validate(JSObject obj) = 0;
  
    // Returns true if a holder contains an element with the specified index
    // 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 nullptr, the
    // holder->elements() is used as the backing store. If a |filter| is
    // specified the PropertyAttributes of the element at the given index
    // are compared to the given |filter|. If they match/overlap the given
    // index is ignored. Note that only Dictionary elements have custom
    // PropertyAttributes associated, hence the |filter| argument is ignored for
    // all but DICTIONARY_ELEMENTS and SLOW_SLOPPY_ARGUMENTS_ELEMENTS.
    virtual bool HasElement(JSObject holder, uint32_t index,
                            FixedArrayBase backing_store,
                            PropertyFilter filter = ALL_PROPERTIES) = 0;
  
    inline bool HasElement(JSObject holder, uint32_t index,
                           PropertyFilter filter = ALL_PROPERTIES);
  
    // Note: this is currently not implemented for string wrapper and
    // typed array elements.
    virtual bool HasEntry(JSObject holder, uint32_t entry) = 0;
  
    // TODO(cbruni): HasEntry and Get should not be exposed publicly with the
    // entry parameter.
    virtual Handle<Object> Get(Handle<JSObject> holder, uint32_t entry) = 0;
  
    virtual bool HasAccessors(JSObject holder) = 0;
    virtual uint32_t NumberOfElements(JSObject holder) = 0;
  
    // 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.
    virtual void SetLength(Handle<JSArray> holder, uint32_t new_length) = 0;
  
    // Copy all indices that have elements from |object| into the given
    // KeyAccumulator. For Dictionary-based element-kinds we filter out elements
    // whose PropertyAttribute match |filter|.
    V8_WARN_UNUSED_RESULT virtual ExceptionStatus CollectElementIndices(
        Handle<JSObject> object, Handle<FixedArrayBase> backing_store,
        KeyAccumulator* keys) = 0;
  
    V8_WARN_UNUSED_RESULT inline ExceptionStatus CollectElementIndices(
        Handle<JSObject> object, KeyAccumulator* keys);
  
    virtual Maybe<bool> CollectValuesOrEntries(
        Isolate* isolate, Handle<JSObject> object,
        Handle<FixedArray> values_or_entries, bool get_entries, int* nof_items,
        PropertyFilter filter = ALL_PROPERTIES) = 0;
  
    virtual MaybeHandle<FixedArray> PrependElementIndices(
        Handle<JSObject> object, Handle<FixedArrayBase> backing_store,
        Handle<FixedArray> keys, GetKeysConversion convert,
        PropertyFilter filter = ALL_PROPERTIES) = 0;
  
    inline MaybeHandle<FixedArray> PrependElementIndices(
        Handle<JSObject> object, Handle<FixedArray> keys,
        GetKeysConversion convert, PropertyFilter filter = ALL_PROPERTIES);
  
    V8_WARN_UNUSED_RESULT virtual ExceptionStatus AddElementsToKeyAccumulator(
        Handle<JSObject> receiver, KeyAccumulator* accumulator,
        AddKeyConversion convert) = 0;
  
    virtual void TransitionElementsKind(Handle<JSObject> object,
                                        Handle<Map> map) = 0;
    virtual void GrowCapacityAndConvert(Handle<JSObject> object,
                                        uint32_t capacity) = 0;
    // Unlike GrowCapacityAndConvert do not attempt to convert the backing store
    // and simply return false in this case.
    virtual bool GrowCapacity(Handle<JSObject> object, uint32_t index) = 0;
  
    static void InitializeOncePerProcess();
    static void TearDown();
  
    virtual void Set(Handle<JSObject> holder, uint32_t entry, Object value) = 0;
  
    virtual void Add(Handle<JSObject> object, uint32_t index,
                     Handle<Object> value, PropertyAttributes attributes,
                     uint32_t new_capacity) = 0;
  
    static Handle<JSArray> Concat(Isolate* isolate, Arguments* args,
                                  uint32_t concat_size, uint32_t result_length);
  
    virtual uint32_t Push(Handle<JSArray> receiver, Arguments* args,
                          uint32_t push_size) = 0;
  
    virtual uint32_t Unshift(Handle<JSArray> receiver, Arguments* args,
                             uint32_t unshift_size) = 0;
  
    virtual Handle<Object> Pop(Handle<JSArray> receiver) = 0;
  
    virtual Handle<Object> Shift(Handle<JSArray> receiver) = 0;
  
    virtual Handle<NumberDictionary> Normalize(Handle<JSObject> object) = 0;
  
    virtual uint32_t GetCapacity(JSObject holder,
                                 FixedArrayBase backing_store) = 0;
  
    virtual Object Fill(Handle<JSObject> receiver, Handle<Object> obj_value,
                        uint32_t start, uint32_t end) = 0;
  
    // Check an Object's own elements for an element (using SameValueZero
    // semantics)
    virtual Maybe<bool> IncludesValue(Isolate* isolate, Handle<JSObject> receiver,
                                      Handle<Object> value, uint32_t start,
                                      uint32_t length) = 0;
  
    // Check an Object's own elements for the index of an element (using SameValue
    // semantics)
    virtual Maybe<int64_t> IndexOfValue(Isolate* isolate,
                                        Handle<JSObject> receiver,
                                        Handle<Object> value, uint32_t start,
                                        uint32_t length) = 0;
  
    virtual Maybe<int64_t> LastIndexOfValue(Handle<JSObject> receiver,
                                            Handle<Object> value,
                                            uint32_t start) = 0;
  
    virtual void Reverse(JSObject receiver) = 0;
  
    virtual void CopyElements(Isolate* isolate, Handle<FixedArrayBase> source,
                              ElementsKind source_kind,
                              Handle<FixedArrayBase> destination, int size) = 0;
  
    virtual Object CopyElements(Handle<Object> source,
                                Handle<JSObject> destination, size_t length,
                                uint32_t offset = 0) = 0;
  
    virtual Handle<FixedArray> CreateListFromArrayLike(Isolate* isolate,
                                                       Handle<JSObject> object,
                                                       uint32_t length) = 0;
  
    virtual void CopyTypedArrayElementsSlice(JSTypedArray source,
                                             JSTypedArray destination,
                                             size_t start, size_t end) = 0;
  
   protected:
    friend class LookupIterator;
  
    // Element handlers distinguish between entries and indices when they
    // manipulate elements. Entries refer to elements in terms of their location
    // in the underlying storage's backing store representation, and are between 0
    // and GetCapacity. Indices refer to elements in terms of the value that would
    // be specified in JavaScript to access the element. In most implementations,
    // indices are equivalent to entries. In the NumberDictionary
    // ElementsAccessor, entries are mapped to an index using the KeyAt method on
    // the NumberDictionary.
    virtual uint32_t GetEntryForIndex(Isolate* isolate, JSObject holder,
                                      FixedArrayBase backing_store,
                                      uint32_t index) = 0;
  
    virtual PropertyDetails GetDetails(JSObject holder, uint32_t entry) = 0;
    virtual void Reconfigure(Handle<JSObject> object,
                             Handle<FixedArrayBase> backing_store, uint32_t entry,
                             Handle<Object> value,
                             PropertyAttributes attributes) = 0;
  
    // Deletes an element in an object.
    virtual void Delete(Handle<JSObject> holder, uint32_t entry) = 0;
  
    // NOTE: this method violates the handlified function signature convention:
    // raw pointer parameter |source_holder| in the function that allocates.
    // This is done intentionally to avoid ArrayConcat() builtin performance
    // degradation.
    virtual void CopyElements(JSObject source_holder, uint32_t source_start,
                              ElementsKind source_kind,
                              Handle<FixedArrayBase> destination,
                              uint32_t destination_start, int copy_size) = 0;
  
   private:
    V8_EXPORT_PRIVATE static ElementsAccessor** elements_accessors_;
  
    DISALLOW_COPY_AND_ASSIGN(ElementsAccessor);
  };
  
  V8_WARN_UNUSED_RESULT MaybeHandle<Object> ArrayConstructInitializeElements(
      Handle<JSArray> array, Arguments* args);
  
  // Called directly from CSA.
  // {raw_context}: Context pointer.
  // {raw_source}: JSArray pointer.
  // {raw_destination}: JSTypedArray pointer.
  void CopyFastNumberJSArrayElementsToTypedArray(Address raw_context,
                                                 Address raw_source,
                                                 Address raw_destination,
                                                 uintptr_t length,
                                                 uintptr_t offset);
  // {raw_source}, {raw_destination}: JSTypedArray pointers.
  void CopyTypedArrayElementsToTypedArray(Address raw_source,
                                          Address raw_destination,
                                          uintptr_t length, uintptr_t offset);
  // {raw_source}, {raw_destination}: JSTypedArray pointers.
  void CopyTypedArrayElementsSlice(Address raw_source, Address raw_destination,
                                   uintptr_t start, uintptr_t end);
  
  }  // namespace internal
  }  // namespace v8
  
  #endif  // V8_OBJECTS_ELEMENTS_H_
  