1 // Copyright 2012 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef V8_ELEMENTS_H_ 6 #define V8_ELEMENTS_H_ 7 8 #include "src/elements-kind.h" 9 #include "src/heap/heap.h" 10 #include "src/isolate.h" 11 #include "src/keys.h" 12 #include "src/objects.h" 13 14 namespace v8 { 15 namespace internal { 16 17 // Abstract base class for handles that can operate on objects with differing 18 // ElementsKinds. 19 class ElementsAccessor { 20 public: 21 explicit ElementsAccessor(const char* name) : name_(name) { } 22 virtual ~ElementsAccessor() { } 23 24 const char* name() const { return name_; } 25 26 // Returns a shared ElementsAccessor for the specified ElementsKind. 27 static ElementsAccessor* ForKind(ElementsKind elements_kind) { 28 DCHECK(static_cast<int>(elements_kind) < kElementsKindCount); 29 return elements_accessors_[elements_kind]; 30 } 31 32 // Checks the elements of an object for consistency, asserting when a problem 33 // is found. 34 virtual void Validate(Handle<JSObject> obj) = 0; 35 36 // Returns true if a holder contains an element with the specified index 37 // without iterating up the prototype chain. The caller can optionally pass 38 // in the backing store to use for the check, which must be compatible with 39 // the ElementsKind of the ElementsAccessor. If backing_store is NULL, the 40 // holder->elements() is used as the backing store. If a |filter| is 41 // specified the PropertyAttributes of the element at the given index 42 // are compared to the given |filter|. If they match/overlap the given 43 // index is ignored. Note that only Dictionary elements have custom 44 // PropertyAttributes associated, hence the |filter| argument is ignored for 45 // all but DICTIONARY_ELEMENTS and SLOW_SLOPPY_ARGUMENTS_ELEMENTS. 46 virtual bool HasElement(Handle<JSObject> holder, uint32_t index, 47 Handle<FixedArrayBase> backing_store, 48 PropertyFilter filter = ALL_PROPERTIES) = 0; 49 50 inline bool HasElement(Handle<JSObject> holder, uint32_t index, 51 PropertyFilter filter = ALL_PROPERTIES) { 52 return HasElement(holder, index, handle(holder->elements()), filter); 53 } 54 55 virtual Handle<Object> Get(Handle<JSObject> holder, uint32_t entry) = 0; 56 57 virtual PropertyDetails GetDetails(JSObject* holder, uint32_t entry) = 0; 58 virtual bool HasAccessors(JSObject* holder) = 0; 59 60 // Modifies the length data property as specified for JSArrays and resizes the 61 // underlying backing store accordingly. The method honors the semantics of 62 // changing array sizes as defined in EcmaScript 5.1 15.4.5.2, i.e. array that 63 // have non-deletable elements can only be shrunk to the size of highest 64 // element that is non-deletable. 65 virtual void SetLength(Handle<JSArray> holder, uint32_t new_length) = 0; 66 67 // Deletes an element in an object. 68 virtual void Delete(Handle<JSObject> holder, uint32_t entry) = 0; 69 70 // If kCopyToEnd is specified as the copy_size to CopyElements, it copies all 71 // of elements from source after source_start to the destination array. 72 static const int kCopyToEnd = -1; 73 // If kCopyToEndAndInitializeToHole is specified as the copy_size to 74 // CopyElements, it copies all of elements from source after source_start to 75 // destination array, padding any remaining uninitialized elements in the 76 // destination array with the hole. 77 static const int kCopyToEndAndInitializeToHole = -2; 78 79 // Copy all indices that have elements from |object| into the given 80 // KeyAccumulator. For Dictionary-based element-kinds we filter out elements 81 // whose PropertyAttribute match |filter|. 82 virtual void CollectElementIndices(Handle<JSObject> object, 83 Handle<FixedArrayBase> backing_store, 84 KeyAccumulator* keys) = 0; 85 86 inline void CollectElementIndices(Handle<JSObject> object, 87 KeyAccumulator* keys) { 88 CollectElementIndices(object, handle(object->elements(), keys->isolate()), 89 keys); 90 } 91 92 virtual Maybe<bool> CollectValuesOrEntries( 93 Isolate* isolate, Handle<JSObject> object, 94 Handle<FixedArray> values_or_entries, bool get_entries, int* nof_items, 95 PropertyFilter filter = ALL_PROPERTIES) = 0; 96 97 virtual Handle<FixedArray> PrependElementIndices( 98 Handle<JSObject> object, Handle<FixedArrayBase> backing_store, 99 Handle<FixedArray> keys, GetKeysConversion convert, 100 PropertyFilter filter = ALL_PROPERTIES) = 0; 101 102 inline Handle<FixedArray> PrependElementIndices( 103 Handle<JSObject> object, Handle<FixedArray> keys, 104 GetKeysConversion convert, PropertyFilter filter = ALL_PROPERTIES) { 105 return PrependElementIndices(object, handle(object->elements()), keys, 106 convert, filter); 107 } 108 109 virtual void AddElementsToKeyAccumulator(Handle<JSObject> receiver, 110 KeyAccumulator* accumulator, 111 AddKeyConversion convert) = 0; 112 113 virtual void GrowCapacityAndConvert(Handle<JSObject> object, 114 uint32_t capacity) = 0; 115 116 static void InitializeOncePerProcess(); 117 static void TearDown(); 118 119 virtual void Set(Handle<JSObject> holder, uint32_t entry, Object* value) = 0; 120 121 virtual void Reconfigure(Handle<JSObject> object, 122 Handle<FixedArrayBase> backing_store, uint32_t entry, 123 Handle<Object> value, 124 PropertyAttributes attributes) = 0; 125 126 virtual void Add(Handle<JSObject> object, uint32_t index, 127 Handle<Object> value, PropertyAttributes attributes, 128 uint32_t new_capacity) = 0; 129 130 static Handle<JSArray> Concat(Isolate* isolate, Arguments* args, 131 uint32_t concat_size, uint32_t result_length); 132 133 virtual uint32_t Push(Handle<JSArray> receiver, Arguments* args, 134 uint32_t push_size) = 0; 135 136 virtual uint32_t Unshift(Handle<JSArray> receiver, 137 Arguments* args, uint32_t unshift_size) = 0; 138 139 virtual Handle<JSArray> Slice(Handle<JSObject> receiver, 140 uint32_t start, uint32_t end) = 0; 141 142 virtual Handle<JSArray> Splice(Handle<JSArray> receiver, 143 uint32_t start, uint32_t delete_count, 144 Arguments* args, uint32_t add_count) = 0; 145 146 virtual Handle<Object> Pop(Handle<JSArray> receiver) = 0; 147 148 virtual Handle<Object> Shift(Handle<JSArray> receiver) = 0; 149 150 virtual Handle<SeededNumberDictionary> Normalize(Handle<JSObject> object) = 0; 151 152 virtual uint32_t GetCapacity(JSObject* holder, 153 FixedArrayBase* backing_store) = 0; 154 155 protected: 156 friend class LookupIterator; 157 158 // Element handlers distinguish between entries and indices when they 159 // manipulate elements. Entries refer to elements in terms of their location 160 // in the underlying storage's backing store representation, and are between 0 161 // and GetCapacity. Indices refer to elements in terms of the value that would 162 // be specified in JavaScript to access the element. In most implementations, 163 // indices are equivalent to entries. In the NumberDictionary 164 // ElementsAccessor, entries are mapped to an index using the KeyAt method on 165 // the NumberDictionary. 166 virtual uint32_t GetEntryForIndex(JSObject* holder, 167 FixedArrayBase* backing_store, 168 uint32_t index) = 0; 169 170 // NOTE: this method violates the handlified function signature convention: 171 // raw pointer parameter |source_holder| in the function that allocates. 172 // This is done intentionally to avoid ArrayConcat() builtin performance 173 // degradation. 174 virtual void CopyElements(JSObject* source_holder, uint32_t source_start, 175 ElementsKind source_kind, 176 Handle<FixedArrayBase> destination, 177 uint32_t destination_start, int copy_size) = 0; 178 179 private: 180 static ElementsAccessor** elements_accessors_; 181 const char* name_; 182 183 DISALLOW_COPY_AND_ASSIGN(ElementsAccessor); 184 }; 185 186 void CheckArrayAbuse(Handle<JSObject> obj, const char* op, uint32_t index, 187 bool allow_appending = false); 188 189 MUST_USE_RESULT MaybeHandle<Object> ArrayConstructInitializeElements( 190 Handle<JSArray> array, 191 Arguments* args); 192 193 } // namespace internal 194 } // namespace v8 195 196 #endif // V8_ELEMENTS_H_ 197
