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/js-objects.h"
11
12namespace v8 {
13namespace internal {
14
15class JSProxy;
16
17enum 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.
35class 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 void CollectPrivateNames(Handle<JSReceiver> receiver,
56 Handle<JSObject> object);
57 Maybe<bool> CollectAccessCheckInterceptorKeys(
58 Handle<AccessCheckInfo> access_check_info, Handle<JSReceiver> receiver,
59 Handle<JSObject> object);
60
61 // Might return directly the object's enum_cache, copy the result before using
62 // as an elements backing store for a JSObject.
63 // Does not throw for uninitialized exports in module namespace objects, so
64 // this has to be checked separately.
65 static Handle<FixedArray> GetOwnEnumPropertyKeys(Isolate* isolate,
66 Handle<JSObject> object);
67
68 void AddKey(Object key, AddKeyConversion convert = DO_NOT_CONVERT);
69 void AddKey(Handle<Object> key, AddKeyConversion convert = DO_NOT_CONVERT);
70 void AddKeys(Handle<FixedArray> array, AddKeyConversion convert);
71 void AddKeys(Handle<JSObject> array_like, AddKeyConversion convert);
72
73 // Jump to the next level, pushing the current |levelLength_| to
74 // |levelLengths_| and adding a new list to |elements_|.
75 Isolate* isolate() { return isolate_; }
76 // Filter keys based on their property descriptors.
77 PropertyFilter filter() { return filter_; }
78 // The collection mode defines whether we collect the keys from the prototype
79 // chain or only look at the receiver.
80 KeyCollectionMode mode() { return mode_; }
81 // In case of for-in loops we have to treat JSProxy keys differently and
82 // deduplicate them. Additionally we convert JSProxy keys back to array
83 // indices.
84 void set_is_for_in(bool value) { is_for_in_ = value; }
85 void set_skip_indices(bool value) { skip_indices_ = value; }
86 // The last_non_empty_prototype is used to limit the prototypes for which
87 // we have to keep track of non-enumerable keys that can shadow keys
88 // repeated on the prototype chain.
89 void set_last_non_empty_prototype(Handle<JSReceiver> object) {
90 last_non_empty_prototype_ = object;
91 }
92 // Shadowing keys are used to filter keys. This happens when non-enumerable
93 // keys appear again on the prototype chain.
94 void AddShadowingKey(Object key);
95 void AddShadowingKey(Handle<Object> key);
96
97 private:
98 Maybe<bool> CollectOwnKeys(Handle<JSReceiver> receiver,
99 Handle<JSObject> object);
100 Maybe<bool> CollectOwnJSProxyKeys(Handle<JSReceiver> receiver,
101 Handle<JSProxy> proxy);
102 Maybe<bool> CollectOwnJSProxyTargetKeys(Handle<JSProxy> proxy,
103 Handle<JSReceiver> target);
104 Maybe<bool> AddKeysFromJSProxy(Handle<JSProxy> proxy,
105 Handle<FixedArray> keys);
106 bool IsShadowed(Handle<Object> key);
107 bool HasShadowingKeys();
108 Handle<OrderedHashSet> keys();
109
110 Isolate* isolate_;
111 // keys_ is either an Handle<OrderedHashSet> or in the case of own JSProxy
112 // keys a Handle<FixedArray>. The OrderedHashSet is in-place converted to the
113 // result list, a FixedArray containing all collected keys.
114 Handle<FixedArray> keys_;
115 Handle<JSReceiver> last_non_empty_prototype_;
116 Handle<ObjectHashSet> shadowing_keys_;
117 KeyCollectionMode mode_;
118 PropertyFilter filter_;
119 bool is_for_in_ = false;
120 bool skip_indices_ = false;
121 // For all the keys on the first receiver adding a shadowing key we can skip
122 // the shadow check.
123 bool skip_shadow_check_ = true;
124
125 DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
126};
127
128// The FastKeyAccumulator handles the cases where there are no elements on the
129// prototype chain and forwords the complex/slow cases to the normal
130// KeyAccumulator. This significantly speeds up the cases where the OWN_ONLY
131// case where we do not have to walk the prototype chain.
132class FastKeyAccumulator {
133 public:
134 FastKeyAccumulator(Isolate* isolate, Handle<JSReceiver> receiver,
135 KeyCollectionMode mode, PropertyFilter filter,
136 bool is_for_in = false, bool skip_indices = false)
137 : isolate_(isolate),
138 receiver_(receiver),
139 mode_(mode),
140 filter_(filter),
141 is_for_in_(is_for_in),
142 skip_indices_(skip_indices) {
143 Prepare();
144 }
145
146 bool is_receiver_simple_enum() { return is_receiver_simple_enum_; }
147 bool has_empty_prototype() { return has_empty_prototype_; }
148
149 MaybeHandle<FixedArray> GetKeys(
150 GetKeysConversion convert = GetKeysConversion::kKeepNumbers);
151
152 private:
153 void Prepare();
154 MaybeHandle<FixedArray> GetKeysFast(GetKeysConversion convert);
155 MaybeHandle<FixedArray> GetKeysSlow(GetKeysConversion convert);
156
157 MaybeHandle<FixedArray> GetOwnKeysWithUninitializedEnumCache();
158
159 Isolate* isolate_;
160 Handle<JSReceiver> receiver_;
161 Handle<JSReceiver> last_non_empty_prototype_;
162 KeyCollectionMode mode_;
163 PropertyFilter filter_;
164 bool is_for_in_ = false;
165 bool skip_indices_ = false;
166 bool is_receiver_simple_enum_ = false;
167 bool has_empty_prototype_ = false;
168
169 DISALLOW_COPY_AND_ASSIGN(FastKeyAccumulator);
170};
171
172} // namespace internal
173} // namespace v8
174
175#endif // V8_KEYS_H_
176