V8 API Reference, 7.2.502.16 (for Deno 0.2.4)
keys.h
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_KEYS_H_
6 #define V8_KEYS_H_
7 
8 #include "src/objects.h"
9 #include "src/objects/hash-table.h"
10 #include "src/objects/ordered-hash-table.h"
11 
12 namespace v8 {
13 namespace internal {
14 
15 class JSProxy;
16 
17 enum AddKeyConversion { DO_NOT_CONVERT, CONVERT_TO_ARRAY_INDEX };
18 
19 // This is a helper class for JSReceiver::GetKeys which collects and sorts keys.
20 // GetKeys needs to sort keys per prototype level, first showing the integer
21 // indices from elements then the strings from the properties. However, this
22 // does not apply to proxies which are in full control of how the keys are
23 // sorted.
24 //
25 // For performance reasons the KeyAccumulator internally separates integer keys
26 // in |elements_| into sorted lists per prototype level. String keys are
27 // collected in |string_properties_|, a single OrderedHashSet (similar for
28 // Symbols in |symbol_properties_|. To separate the keys per level later when
29 // assembling the final list, |levelLengths_| keeps track of the number of
30 // String and Symbol keys per level.
31 //
32 // Only unique keys are kept by the KeyAccumulator, strings are stored in a
33 // HashSet for inexpensive lookups. Integer keys are kept in sorted lists which
34 // are more compact and allow for reasonably fast includes check.
35 class KeyAccumulator final {
36  public:
37  KeyAccumulator(Isolate* isolate, KeyCollectionMode mode,
38  PropertyFilter filter)
39  : isolate_(isolate), mode_(mode), filter_(filter) {}
40  ~KeyAccumulator() = default;
41 
42  static MaybeHandle<FixedArray> GetKeys(
43  Handle<JSReceiver> object, KeyCollectionMode mode, PropertyFilter filter,
44  GetKeysConversion keys_conversion = GetKeysConversion::kKeepNumbers,
45  bool is_for_in = false, bool skip_indices = false);
46 
47  Handle<FixedArray> GetKeys(
48  GetKeysConversion convert = GetKeysConversion::kKeepNumbers);
49  Maybe<bool> CollectKeys(Handle<JSReceiver> receiver,
50  Handle<JSReceiver> object);
51  Maybe<bool> CollectOwnElementIndices(Handle<JSReceiver> receiver,
52  Handle<JSObject> object);
53  Maybe<bool> CollectOwnPropertyNames(Handle<JSReceiver> receiver,
54  Handle<JSObject> object);
55  Maybe<bool> CollectAccessCheckInterceptorKeys(
56  Handle<AccessCheckInfo> access_check_info, Handle<JSReceiver> receiver,
57  Handle<JSObject> object);
58 
59  // Might return directly the object's enum_cache, copy the result before using
60  // as an elements backing store for a JSObject.
61  // Does not throw for uninitialized exports in module namespace objects, so
62  // this has to be checked separately.
63  static Handle<FixedArray> GetOwnEnumPropertyKeys(Isolate* isolate,
64  Handle<JSObject> object);
65 
66  void AddKey(Object* key, AddKeyConversion convert = DO_NOT_CONVERT);
67  void AddKey(Handle<Object> key, AddKeyConversion convert = DO_NOT_CONVERT);
68  void AddKeys(Handle<FixedArray> array, AddKeyConversion convert);
69  void AddKeys(Handle<JSObject> array_like, AddKeyConversion convert);
70 
71  // Jump to the next level, pushing the current |levelLength_| to
72  // |levelLengths_| and adding a new list to |elements_|.
73  Isolate* isolate() { return isolate_; }
74  // Filter keys based on their property descriptors.
75  PropertyFilter filter() { return filter_; }
76  // The collection mode defines whether we collect the keys from the prototype
77  // chain or only look at the receiver.
78  KeyCollectionMode mode() { return mode_; }
79  // In case of for-in loops we have to treat JSProxy keys differently and
80  // deduplicate them. Additionally we convert JSProxy keys back to array
81  // indices.
82  void set_is_for_in(bool value) { is_for_in_ = value; }
83  void set_skip_indices(bool value) { skip_indices_ = value; }
84  // The last_non_empty_prototype is used to limit the prototypes for which
85  // we have to keep track of non-enumerable keys that can shadow keys
86  // repeated on the prototype chain.
87  void set_last_non_empty_prototype(Handle<JSReceiver> object) {
88  last_non_empty_prototype_ = object;
89  }
90  // Shadowing keys are used to filter keys. This happens when non-enumerable
91  // keys appear again on the prototype chain.
92  void AddShadowingKey(Object* key);
93  void AddShadowingKey(Handle<Object> key);
94 
95  private:
96  Maybe<bool> CollectOwnKeys(Handle<JSReceiver> receiver,
97  Handle<JSObject> object);
98  Maybe<bool> CollectOwnJSProxyKeys(Handle<JSReceiver> receiver,
99  Handle<JSProxy> proxy);
100  Maybe<bool> CollectOwnJSProxyTargetKeys(Handle<JSProxy> proxy,
101  Handle<JSReceiver> target);
102  Maybe<bool> AddKeysFromJSProxy(Handle<JSProxy> proxy,
103  Handle<FixedArray> keys);
104  bool IsShadowed(Handle<Object> key);
105  bool HasShadowingKeys();
106  Handle<OrderedHashSet> keys();
107 
108  Isolate* isolate_;
109  // keys_ is either an Handle<OrderedHashSet> or in the case of own JSProxy
110  // keys a Handle<FixedArray>. The OrderedHashSet is in-place converted to the
111  // result list, a FixedArray containing all collected keys.
112  Handle<FixedArray> keys_;
113  Handle<JSReceiver> last_non_empty_prototype_;
114  Handle<ObjectHashSet> shadowing_keys_;
115  KeyCollectionMode mode_;
116  PropertyFilter filter_;
117  bool is_for_in_ = false;
118  bool skip_indices_ = false;
119  // For all the keys on the first receiver adding a shadowing key we can skip
120  // the shadow check.
121  bool skip_shadow_check_ = true;
122 
123  DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
124 };
125 
126 // The FastKeyAccumulator handles the cases where there are no elements on the
127 // prototype chain and forwords the complex/slow cases to the normal
128 // KeyAccumulator. This significantly speeds up the cases where the OWN_ONLY
129 // case where we do not have to walk the prototype chain.
131  public:
132  FastKeyAccumulator(Isolate* isolate, Handle<JSReceiver> receiver,
133  KeyCollectionMode mode, PropertyFilter filter,
134  bool is_for_in = false, bool skip_indices = false)
135  : isolate_(isolate),
136  receiver_(receiver),
137  mode_(mode),
138  filter_(filter),
139  is_for_in_(is_for_in),
140  skip_indices_(skip_indices) {
141  Prepare();
142  }
143 
144  bool is_receiver_simple_enum() { return is_receiver_simple_enum_; }
145  bool has_empty_prototype() { return has_empty_prototype_; }
146 
147  MaybeHandle<FixedArray> GetKeys(
148  GetKeysConversion convert = GetKeysConversion::kKeepNumbers);
149 
150  private:
151  void Prepare();
152  MaybeHandle<FixedArray> GetKeysFast(GetKeysConversion convert);
153  MaybeHandle<FixedArray> GetKeysSlow(GetKeysConversion convert);
154 
155  MaybeHandle<FixedArray> GetOwnKeysWithUninitializedEnumCache();
156 
157  Isolate* isolate_;
158  Handle<JSReceiver> receiver_;
159  Handle<JSReceiver> last_non_empty_prototype_;
160  KeyCollectionMode mode_;
161  PropertyFilter filter_;
162  bool is_for_in_ = false;
163  bool skip_indices_ = false;
164  bool is_receiver_simple_enum_ = false;
165  bool has_empty_prototype_ = false;
166 
167  DISALLOW_COPY_AND_ASSIGN(FastKeyAccumulator);
168 };
169 
170 } // namespace internal
171 } // namespace v8
172 
173 #endif // V8_KEYS_H_
Definition: v8.h:56
Definition: libplatform.h:13