elements.h 11.2 KB
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// Copyright 2012 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
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#ifndef V8_ELEMENTS_H_
#define V8_ELEMENTS_H_

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#include "src/elements-kind.h"
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#include "src/keys.h"
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#include "src/objects.h"
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namespace v8 {
namespace internal {

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class JSTypedArray;

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// Abstract base class for handles that can operate on objects with differing
// ElementsKinds.
class ElementsAccessor {
 public:
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  explicit ElementsAccessor(const char* name) : name_(name) { }
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  virtual ~ElementsAccessor() = default;
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  const char* name() const { return name_; }
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  // Returns a shared ElementsAccessor for the specified ElementsKind.
  static ElementsAccessor* ForKind(ElementsKind elements_kind) {
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    DCHECK_LT(static_cast<int>(elements_kind), kElementsKindCount);
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    return elements_accessors_[elements_kind];
  }

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  // Checks the elements of an object for consistency, asserting when a problem
  // is found.
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  virtual void Validate(JSObject obj) = 0;
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  // Returns true if a holder contains an element with the specified index
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  // 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
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  // the ElementsKind of the ElementsAccessor. If backing_store is nullptr, the
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  // 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.
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  virtual bool HasElement(JSObject holder, uint32_t index,
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                          FixedArrayBase backing_store,
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                          PropertyFilter filter = ALL_PROPERTIES) = 0;
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  inline bool HasElement(JSObject holder, uint32_t index,
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                         PropertyFilter filter = ALL_PROPERTIES);
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  // Note: this is currently not implemented for string wrapper and
  // typed array elements.
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  virtual bool HasEntry(JSObject holder, uint32_t entry) = 0;
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  // TODO(cbruni): HasEntry and Get should not be exposed publicly with the
  // entry parameter.
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  virtual Handle<Object> Get(Handle<JSObject> holder, uint32_t entry) = 0;

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  virtual bool HasAccessors(JSObject holder) = 0;
  virtual uint32_t NumberOfElements(JSObject holder) = 0;
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  // 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.
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  virtual void SetLength(Handle<JSArray> holder, uint32_t new_length) = 0;
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  // 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;

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  // 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|.
  virtual void CollectElementIndices(Handle<JSObject> object,
                                     Handle<FixedArrayBase> backing_store,
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                                     KeyAccumulator* keys) = 0;
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  inline void CollectElementIndices(Handle<JSObject> object,
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                                    KeyAccumulator* keys);
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  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;

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  virtual MaybeHandle<FixedArray> PrependElementIndices(
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      Handle<JSObject> object, Handle<FixedArrayBase> backing_store,
      Handle<FixedArray> keys, GetKeysConversion convert,
      PropertyFilter filter = ALL_PROPERTIES) = 0;

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  inline MaybeHandle<FixedArray> PrependElementIndices(
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      Handle<JSObject> object, Handle<FixedArray> keys,
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      GetKeysConversion convert, PropertyFilter filter = ALL_PROPERTIES);
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  virtual void AddElementsToKeyAccumulator(Handle<JSObject> receiver,
                                           KeyAccumulator* accumulator,
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                                           AddKeyConversion convert) = 0;
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  virtual void TransitionElementsKind(Handle<JSObject> object,
                                      Handle<Map> map) = 0;
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  virtual void GrowCapacityAndConvert(Handle<JSObject> object,
                                      uint32_t capacity) = 0;
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  // 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;
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  static void InitializeOncePerProcess();
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  static void TearDown();
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  virtual void Set(Handle<JSObject> holder, uint32_t entry, Object value) = 0;
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  virtual void Add(Handle<JSObject> object, uint32_t index,
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                   Handle<Object> value, PropertyAttributes attributes,
                   uint32_t new_capacity) = 0;
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  static Handle<JSArray> Concat(Isolate* isolate, Arguments* args,
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                                uint32_t concat_size, uint32_t result_length);
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  virtual uint32_t Push(Handle<JSArray> receiver, Arguments* args,
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                        uint32_t push_size) = 0;
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  virtual uint32_t Unshift(Handle<JSArray> receiver, Arguments* args,
                           uint32_t unshift_size) = 0;
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  virtual Handle<JSObject> Slice(Handle<JSObject> receiver, uint32_t start,
                                 uint32_t end) = 0;

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  virtual Handle<Object> Pop(Handle<JSArray> receiver) = 0;
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  virtual Handle<Object> Shift(Handle<JSArray> receiver) = 0;
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  virtual Handle<NumberDictionary> Normalize(Handle<JSObject> object) = 0;
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  virtual uint32_t GetCapacity(JSObject holder,
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                               FixedArrayBase backing_store) = 0;
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  virtual Object Fill(Handle<JSObject> receiver, Handle<Object> obj_value,
                      uint32_t start, uint32_t end) = 0;
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  // 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;

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  // 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;

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  virtual Maybe<int64_t> LastIndexOfValue(Handle<JSObject> receiver,
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                                          Handle<Object> value,
                                          uint32_t start) = 0;

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  virtual void Reverse(JSObject receiver) = 0;
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  virtual void CopyElements(Isolate* isolate, Handle<FixedArrayBase> source,
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                            ElementsKind source_kind,
                            Handle<FixedArrayBase> destination, int size) = 0;

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  virtual Object CopyElements(Handle<Object> source,
                              Handle<JSObject> destination, size_t length,
                              uint32_t offset = 0) = 0;
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  virtual Handle<FixedArray> CreateListFromArrayLike(Isolate* isolate,
                                                     Handle<JSObject> object,
                                                     uint32_t length) = 0;
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  virtual void CopyTypedArrayElementsSlice(JSTypedArray source,
                                           JSTypedArray destination,
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                                           size_t start, size_t end) = 0;

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 protected:
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  friend class LookupIterator;
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  // 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.
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  virtual uint32_t GetEntryForIndex(Isolate* isolate, JSObject holder,
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                                    FixedArrayBase backing_store,
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                                    uint32_t index) = 0;
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  virtual PropertyDetails GetDetails(JSObject holder, uint32_t entry) = 0;
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  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;

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  // 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.
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  virtual void CopyElements(JSObject source_holder, uint32_t source_start,
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                            ElementsKind source_kind,
                            Handle<FixedArrayBase> destination,
                            uint32_t destination_start, int copy_size) = 0;
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 private:
  static ElementsAccessor** elements_accessors_;
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  const char* name_;
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  DISALLOW_COPY_AND_ASSIGN(ElementsAccessor);
};

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void CheckArrayAbuse(Handle<JSObject> obj, const char* op, uint32_t index,
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                     bool allow_appending = false);
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V8_WARN_UNUSED_RESULT MaybeHandle<Object> ArrayConstructInitializeElements(
    Handle<JSArray> array, Arguments* args);
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// Called directly from CSA.
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// {raw_context}: Context pointer.
// {raw_source}: JSArray pointer.
// {raw_destination}: JSTypedArray pointer.
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void CopyFastNumberJSArrayElementsToTypedArray(Address raw_context,
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                                               Address raw_source,
                                               Address raw_destination,
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                                               uintptr_t length,
                                               uintptr_t offset);
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// {raw_source}, {raw_destination}: JSTypedArray pointers.
void CopyTypedArrayElementsToTypedArray(Address raw_source,
                                        Address raw_destination,
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                                        uintptr_t length, uintptr_t offset);
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// {raw_source}, {raw_destination}: JSTypedArray pointers.
void CopyTypedArrayElementsSlice(Address raw_source, Address raw_destination,
                                 uintptr_t start, uintptr_t end);
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}  // namespace internal
}  // namespace v8
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#endif  // V8_ELEMENTS_H_