elements.h revision f91f0611dbaf29ca0f1d4aecb357ce243a19d2fa 
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
14namespace v8 {
15namespace internal {
16
17// Abstract base class for handles that can operate on objects with differing
18// ElementsKinds.
19class 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 MaybeHandle<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 MaybeHandle<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 TransitionElementsKind(Handle<JSObject> object,
114                                      Handle<Map> map) = 0;
115  virtual void GrowCapacityAndConvert(Handle<JSObject> object,
116                                      uint32_t capacity) = 0;
117
118  static void InitializeOncePerProcess();
119  static void TearDown();
120
121  virtual void Set(Handle<JSObject> holder, uint32_t entry, Object* value) = 0;
122
123  virtual void Reconfigure(Handle<JSObject> object,
124                           Handle<FixedArrayBase> backing_store, uint32_t entry,
125                           Handle<Object> value,
126                           PropertyAttributes attributes) = 0;
127
128  virtual void Add(Handle<JSObject> object, uint32_t index,
129                   Handle<Object> value, PropertyAttributes attributes,
130                   uint32_t new_capacity) = 0;
131
132  static Handle<JSArray> Concat(Isolate* isolate, Arguments* args,
133                                uint32_t concat_size, uint32_t result_length);
134
135  virtual uint32_t Push(Handle<JSArray> receiver, Arguments* args,
136                        uint32_t push_size) = 0;
137
138  virtual uint32_t Unshift(Handle<JSArray> receiver,
139                           Arguments* args, uint32_t unshift_size) = 0;
140
141  virtual Handle<JSArray> Slice(Handle<JSObject> receiver,
142                                uint32_t start, uint32_t end) = 0;
143
144  virtual Handle<JSArray> Splice(Handle<JSArray> receiver,
145                                 uint32_t start, uint32_t delete_count,
146                                 Arguments* args, uint32_t add_count) = 0;
147
148  virtual Handle<Object> Pop(Handle<JSArray> receiver) = 0;
149
150  virtual Handle<Object> Shift(Handle<JSArray> receiver) = 0;
151
152  virtual Handle<SeededNumberDictionary> Normalize(Handle<JSObject> object) = 0;
153
154  virtual uint32_t GetCapacity(JSObject* holder,
155                               FixedArrayBase* backing_store) = 0;
156
157  // Check an Object's own elements for an element (using SameValueZero
158  // semantics)
159  virtual Maybe<bool> IncludesValue(Isolate* isolate, Handle<JSObject> receiver,
160                                    Handle<Object> value, uint32_t start,
161                                    uint32_t length) = 0;
162
163  // Check an Object's own elements for the index of an element (using SameValue
164  // semantics)
165  virtual Maybe<int64_t> IndexOfValue(Isolate* isolate,
166                                      Handle<JSObject> receiver,
167                                      Handle<Object> value, uint32_t start,
168                                      uint32_t length) = 0;
169
170 protected:
171  friend class LookupIterator;
172
173  // Element handlers distinguish between entries and indices when they
174  // manipulate elements. Entries refer to elements in terms of their location
175  // in the underlying storage's backing store representation, and are between 0
176  // and GetCapacity. Indices refer to elements in terms of the value that would
177  // be specified in JavaScript to access the element. In most implementations,
178  // indices are equivalent to entries. In the NumberDictionary
179  // ElementsAccessor, entries are mapped to an index using the KeyAt method on
180  // the NumberDictionary.
181  virtual uint32_t GetEntryForIndex(JSObject* holder,
182                                    FixedArrayBase* backing_store,
183                                    uint32_t index) = 0;
184
185  // NOTE: this method violates the handlified function signature convention:
186  // raw pointer parameter |source_holder| in the function that allocates.
187  // This is done intentionally to avoid ArrayConcat() builtin performance
188  // degradation.
189  virtual void CopyElements(JSObject* source_holder, uint32_t source_start,
190                            ElementsKind source_kind,
191                            Handle<FixedArrayBase> destination,
192                            uint32_t destination_start, int copy_size) = 0;
193
194 private:
195  static ElementsAccessor** elements_accessors_;
196  const char* name_;
197
198  DISALLOW_COPY_AND_ASSIGN(ElementsAccessor);
199};
200
201void CheckArrayAbuse(Handle<JSObject> obj, const char* op, uint32_t index,
202                     bool allow_appending = false);
203
204MUST_USE_RESULT MaybeHandle<Object> ArrayConstructInitializeElements(
205    Handle<JSArray> array,
206    Arguments* args);
207
208}  // namespace internal
209}  // namespace v8
210
211#endif  // V8_ELEMENTS_H_
212