16c2c72ade
BUG= Review URL: https://codereview.chromium.org/489033002 git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@23240 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
226 lines
8.7 KiB
C++
226 lines
8.7 KiB
C++
// 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
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// found in the LICENSE file.
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#ifndef V8_ELEMENTS_H_
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#define V8_ELEMENTS_H_
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#include "src/elements-kind.h"
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#include "src/heap/heap.h"
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#include "src/isolate.h"
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#include "src/objects.h"
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namespace v8 {
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namespace internal {
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// Abstract base class for handles that can operate on objects with differing
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// ElementsKinds.
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class ElementsAccessor {
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public:
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explicit ElementsAccessor(const char* name) : name_(name) { }
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virtual ~ElementsAccessor() { }
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virtual ElementsKind kind() const = 0;
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const char* name() const { return name_; }
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// Checks the elements of an object for consistency, asserting when a problem
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// is found.
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virtual void Validate(Handle<JSObject> obj) = 0;
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// Returns true if a holder contains an element with the specified key
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// without iterating up the prototype chain. The caller can optionally pass
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// 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 NULL, the
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// holder->elements() is used as the backing store.
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virtual bool HasElement(
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Handle<Object> receiver,
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Handle<JSObject> holder,
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uint32_t key,
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Handle<FixedArrayBase> backing_store) = 0;
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inline bool HasElement(
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Handle<Object> receiver,
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Handle<JSObject> holder,
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uint32_t key) {
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return HasElement(receiver, holder, key, handle(holder->elements()));
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}
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// Returns the element with the specified key or undefined if there is no such
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// element. This method doesn't iterate up the prototype chain. The caller
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// can optionally pass in the backing store to use for the check, which must
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// be compatible with the ElementsKind of the ElementsAccessor. If
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// backing_store is NULL, the holder->elements() is used as the backing store.
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MUST_USE_RESULT virtual MaybeHandle<Object> Get(
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Handle<Object> receiver,
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Handle<JSObject> holder,
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uint32_t key,
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Handle<FixedArrayBase> backing_store) = 0;
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MUST_USE_RESULT inline MaybeHandle<Object> Get(
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Handle<Object> receiver,
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Handle<JSObject> holder,
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uint32_t key) {
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return Get(receiver, holder, key, handle(holder->elements()));
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}
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// Returns an element's attributes, or ABSENT if there is no such
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// element. This method doesn't iterate up the prototype chain. The caller
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// can optionally pass in the backing store to use for the check, which must
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// be compatible with the ElementsKind of the ElementsAccessor. If
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// backing_store is NULL, the holder->elements() is used as the backing store.
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MUST_USE_RESULT virtual PropertyAttributes GetAttributes(
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Handle<Object> receiver,
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Handle<JSObject> holder,
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uint32_t key,
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Handle<FixedArrayBase> backing_store) = 0;
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MUST_USE_RESULT inline PropertyAttributes GetAttributes(
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Handle<Object> receiver,
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Handle<JSObject> holder,
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uint32_t key) {
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return GetAttributes(receiver, holder, key, handle(holder->elements()));
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}
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// Returns an element's accessors, or NULL if the element does not exist or
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// is plain. This method doesn't iterate up the prototype chain. The caller
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// can optionally pass in the backing store to use for the check, which must
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// be compatible with the ElementsKind of the ElementsAccessor. If
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// backing_store is NULL, the holder->elements() is used as the backing store.
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MUST_USE_RESULT virtual MaybeHandle<AccessorPair> GetAccessorPair(
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Handle<Object> receiver,
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Handle<JSObject> holder,
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uint32_t key,
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Handle<FixedArrayBase> backing_store) = 0;
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MUST_USE_RESULT inline MaybeHandle<AccessorPair> GetAccessorPair(
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Handle<Object> receiver,
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Handle<JSObject> holder,
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uint32_t key) {
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return GetAccessorPair(receiver, holder, key, handle(holder->elements()));
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}
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// Modifies the length data property as specified for JSArrays and resizes the
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// underlying backing store accordingly. The method honors the semantics of
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// changing array sizes as defined in EcmaScript 5.1 15.4.5.2, i.e. array that
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// have non-deletable elements can only be shrunk to the size of highest
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// element that is non-deletable.
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MUST_USE_RESULT virtual MaybeHandle<Object> SetLength(
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Handle<JSArray> holder,
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Handle<Object> new_length) = 0;
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// Modifies both the length and capacity of a JSArray, resizing the underlying
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// backing store as necessary. This method does NOT honor the semantics of
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// EcmaScript 5.1 15.4.5.2, arrays can be shrunk beyond non-deletable
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// elements. This method should only be called for array expansion OR by
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// runtime JavaScript code that use InternalArrays and don't care about
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// EcmaScript 5.1 semantics.
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virtual void SetCapacityAndLength(
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Handle<JSArray> array,
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int capacity,
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int length) = 0;
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// Deletes an element in an object, returning a new elements backing store.
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MUST_USE_RESULT virtual MaybeHandle<Object> Delete(
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Handle<JSObject> holder,
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uint32_t key,
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JSReceiver::DeleteMode mode) = 0;
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// If kCopyToEnd is specified as the copy_size to CopyElements, it copies all
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// of elements from source after source_start to the destination array.
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static const int kCopyToEnd = -1;
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// If kCopyToEndAndInitializeToHole is specified as the copy_size to
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// CopyElements, it copies all of elements from source after source_start to
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// destination array, padding any remaining uninitialized elements in the
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// destination array with the hole.
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static const int kCopyToEndAndInitializeToHole = -2;
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// Copy elements from one backing store to another. Typically, callers specify
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// the source JSObject or JSArray in source_holder. If the holder's backing
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// store is available, it can be passed in source and source_holder is
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// ignored.
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virtual void CopyElements(
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Handle<FixedArrayBase> source,
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uint32_t source_start,
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ElementsKind source_kind,
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Handle<FixedArrayBase> destination,
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uint32_t destination_start,
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int copy_size) = 0;
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// TODO(ishell): Keeping |source_holder| parameter in a non-handlified form
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// helps avoiding ArrayConcat() builtin performance degradation.
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// Revisit this later.
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virtual void CopyElements(
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JSObject* source_holder,
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uint32_t source_start,
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ElementsKind source_kind,
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Handle<FixedArrayBase> destination,
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uint32_t destination_start,
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int copy_size) = 0;
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inline void CopyElements(
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Handle<JSObject> from_holder,
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Handle<FixedArrayBase> to,
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ElementsKind from_kind) {
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CopyElements(
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*from_holder, 0, from_kind, to, 0, kCopyToEndAndInitializeToHole);
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}
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MUST_USE_RESULT virtual MaybeHandle<FixedArray> AddElementsToFixedArray(
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Handle<Object> receiver,
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Handle<JSObject> holder,
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Handle<FixedArray> to,
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Handle<FixedArrayBase> from) = 0;
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MUST_USE_RESULT inline MaybeHandle<FixedArray> AddElementsToFixedArray(
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Handle<Object> receiver,
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Handle<JSObject> holder,
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Handle<FixedArray> to) {
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return AddElementsToFixedArray(
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receiver, holder, to, handle(holder->elements()));
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}
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// Returns a shared ElementsAccessor for the specified ElementsKind.
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static ElementsAccessor* ForKind(ElementsKind elements_kind) {
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DCHECK(elements_kind < kElementsKindCount);
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return elements_accessors_[elements_kind];
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}
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static ElementsAccessor* ForArray(Handle<FixedArrayBase> array);
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static void InitializeOncePerProcess();
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static void TearDown();
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protected:
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friend class SloppyArgumentsElementsAccessor;
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virtual uint32_t GetCapacity(Handle<FixedArrayBase> backing_store) = 0;
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// Element handlers distinguish between indexes and keys when they manipulate
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// elements. Indexes refer to elements in terms of their location in the
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// underlying storage's backing store representation, and are between 0 and
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// GetCapacity. Keys refer to elements in terms of the value that would be
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// specified in JavaScript to access the element. In most implementations,
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// keys are equivalent to indexes, and GetKeyForIndex returns the same value
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// it is passed. In the NumberDictionary ElementsAccessor, GetKeyForIndex maps
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// the index to a key using the KeyAt method on the NumberDictionary.
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virtual uint32_t GetKeyForIndex(Handle<FixedArrayBase> backing_store,
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uint32_t index) = 0;
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private:
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static ElementsAccessor** elements_accessors_;
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const char* name_;
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DISALLOW_COPY_AND_ASSIGN(ElementsAccessor);
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};
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void CheckArrayAbuse(Handle<JSObject> obj, const char* op, uint32_t key,
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bool allow_appending = false);
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MUST_USE_RESULT MaybeHandle<Object> ArrayConstructInitializeElements(
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Handle<JSArray> array,
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Arguments* args);
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} } // namespace v8::internal
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#endif // V8_ELEMENTS_H_
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