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/isolate.h"
9#include "src/objects.h"
10
11namespace v8 {
12namespace internal {
13
14enum AddKeyConversion { DO_NOT_CONVERT, CONVERT_TO_ARRAY_INDEX };
15
16// This is a helper class for JSReceiver::GetKeys which collects and sorts keys.
17// GetKeys needs to sort keys per prototype level, first showing the integer
18// indices from elements then the strings from the properties. However, this
19// does not apply to proxies which are in full control of how the keys are
20// sorted.
21//
22// For performance reasons the KeyAccumulator internally separates integer keys
23// in |elements_| into sorted lists per prototype level. String keys are
24// collected in |string_properties_|, a single OrderedHashSet (similar for
25// Symbols in |symbol_properties_|. To separate the keys per level later when
26// assembling the final list, |levelLengths_| keeps track of the number of
27// String and Symbol keys per level.
28//
29// Only unique keys are kept by the KeyAccumulator, strings are stored in a
30// HashSet for inexpensive lookups. Integer keys are kept in sorted lists which
31// are more compact and allow for reasonably fast includes check.
32class KeyAccumulator final BASE_EMBEDDED {
33 public:
34  KeyAccumulator(Isolate* isolate, KeyCollectionMode mode,
35                 PropertyFilter filter)
36      : isolate_(isolate), mode_(mode), filter_(filter) {}
37  ~KeyAccumulator();
38
39  static MaybeHandle<FixedArray> GetKeys(
40      Handle<JSReceiver> object, KeyCollectionMode mode, PropertyFilter filter,
41      GetKeysConversion keys_conversion = GetKeysConversion::kKeepNumbers,
42      bool is_for_in = false);
43
44  Handle<FixedArray> GetKeys(
45      GetKeysConversion convert = GetKeysConversion::kKeepNumbers);
46  Maybe<bool> CollectKeys(Handle<JSReceiver> receiver,
47                          Handle<JSReceiver> object);
48  Maybe<bool> CollectOwnElementIndices(Handle<JSReceiver> receiver,
49                                       Handle<JSObject> object);
50  Maybe<bool> CollectOwnPropertyNames(Handle<JSReceiver> receiver,
51                                      Handle<JSObject> object);
52  Maybe<bool> CollectAccessCheckInterceptorKeys(
53      Handle<AccessCheckInfo> access_check_info, Handle<JSReceiver> receiver,
54      Handle<JSObject> object);
55
56  // Might return directly the object's enum_cache, copy the result before using
57  // as an elements backing store for a JSObject.
58  static Handle<FixedArray> GetOwnEnumPropertyKeys(Isolate* isolate,
59                                                   Handle<JSObject> object);
60  void AddKey(Object* key, AddKeyConversion convert = DO_NOT_CONVERT);
61  void AddKey(Handle<Object> key, AddKeyConversion convert = DO_NOT_CONVERT);
62  void AddKeys(Handle<FixedArray> array, AddKeyConversion convert);
63  void AddKeys(Handle<JSObject> array_like, AddKeyConversion convert);
64
65  // Jump to the next level, pushing the current |levelLength_| to
66  // |levelLengths_| and adding a new list to |elements_|.
67  Isolate* isolate() { return isolate_; }
68  // Filter keys based on their property descriptors.
69  PropertyFilter filter() { return filter_; }
70  // The collection mode defines whether we collect the keys from the prototype
71  // chain or only look at the receiver.
72  KeyCollectionMode mode() { return mode_; }
73  // In case of for-in loops we have to treat JSProxy keys differently and
74  // deduplicate them. Additionally we convert JSProxy keys back to array
75  // indices.
76  void set_is_for_in(bool value) { is_for_in_ = value; }
77  void set_skip_indices(bool value) { skip_indices_ = value; }
78  // The last_non_empty_prototype is used to limit the prototypes for which
79  // we have to keep track of non-enumerable keys that can shadow keys
80  // repeated on the prototype chain.
81  void set_last_non_empty_prototype(Handle<JSReceiver> object) {
82    last_non_empty_prototype_ = object;
83  }
84  // Shadowing keys are used to filter keys. This happens when non-enumerable
85  // keys appear again on the prototype chain.
86  void AddShadowingKey(Object* key);
87  void AddShadowingKey(Handle<Object> key);
88
89 private:
90  Maybe<bool> CollectOwnKeys(Handle<JSReceiver> receiver,
91                             Handle<JSObject> object);
92  Maybe<bool> CollectOwnJSProxyKeys(Handle<JSReceiver> receiver,
93                                    Handle<JSProxy> proxy);
94  Maybe<bool> CollectOwnJSProxyTargetKeys(Handle<JSProxy> proxy,
95                                          Handle<JSReceiver> target);
96  Maybe<bool> AddKeysFromJSProxy(Handle<JSProxy> proxy,
97                                 Handle<FixedArray> keys);
98  bool IsShadowed(Handle<Object> key);
99  bool HasShadowingKeys();
100  Handle<OrderedHashSet> keys() { return Handle<OrderedHashSet>::cast(keys_); }
101
102  Isolate* isolate_;
103  // keys_ is either an Handle<OrderedHashSet> or in the case of own JSProxy
104  // keys a Handle<FixedArray>. The OrderedHashSet is in-place converted to the
105  // result list, a FixedArray containing all collected keys.
106  Handle<FixedArray> keys_;
107  Handle<JSReceiver> last_non_empty_prototype_;
108  Handle<ObjectHashSet> shadowing_keys_;
109  KeyCollectionMode mode_;
110  PropertyFilter filter_;
111  bool is_for_in_ = false;
112  bool skip_indices_ = false;
113  // For all the keys on the first receiver adding a shadowing key we can skip
114  // the shadow check.
115  bool skip_shadow_check_ = true;
116
117  DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
118};
119
120// The FastKeyAccumulator handles the cases where there are no elements on the
121// prototype chain and forwords the complex/slow cases to the normal
122// KeyAccumulator. This significantly speeds up the cases where the OWN_ONLY
123// case where we do not have to walk the prototype chain.
124class FastKeyAccumulator {
125 public:
126  FastKeyAccumulator(Isolate* isolate, Handle<JSReceiver> receiver,
127                     KeyCollectionMode mode, PropertyFilter filter)
128      : isolate_(isolate), receiver_(receiver), mode_(mode), filter_(filter) {
129    Prepare();
130  }
131
132  bool is_receiver_simple_enum() { return is_receiver_simple_enum_; }
133  bool has_empty_prototype() { return has_empty_prototype_; }
134  void set_is_for_in(bool value) { is_for_in_ = value; }
135
136  MaybeHandle<FixedArray> GetKeys(
137      GetKeysConversion convert = GetKeysConversion::kKeepNumbers);
138
139 private:
140  void Prepare();
141  MaybeHandle<FixedArray> GetKeysFast(GetKeysConversion convert);
142  MaybeHandle<FixedArray> GetKeysSlow(GetKeysConversion convert);
143
144  MaybeHandle<FixedArray> GetOwnKeysWithUninitializedEnumCache();
145
146  Isolate* isolate_;
147  Handle<JSReceiver> receiver_;
148  Handle<JSReceiver> last_non_empty_prototype_;
149  KeyCollectionMode mode_;
150  PropertyFilter filter_;
151  bool is_for_in_ = false;
152  bool is_receiver_simple_enum_ = false;
153  bool has_empty_prototype_ = false;
154
155  DISALLOW_COPY_AND_ASSIGN(FastKeyAccumulator);
156};
157
158}  // namespace internal
159}  // namespace v8
160
161#endif  // V8_KEYS_H_
162