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_KEY_ACCUMULATOR_H_
6 #define V8_KEY_ACCUMULATOR_H_
7 
8 #include "src/isolate.h"
9 #include "src/objects.h"
10 
11 namespace v8 {
12 namespace internal {
13 
14 enum AddKeyConversion { DO_NOT_CONVERT, CONVERT_TO_ARRAY_INDEX, PROXY_MAGIC };
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.
32 class KeyAccumulator final BASE_EMBEDDED {
33  public:
KeyAccumulator(Isolate * isolate,PropertyFilter filter)34   KeyAccumulator(Isolate* isolate, PropertyFilter filter)
35       : isolate_(isolate), filter_(filter) {}
36   ~KeyAccumulator();
37 
38   bool AddKey(uint32_t key);
39   bool AddKey(Object* key, AddKeyConversion convert = DO_NOT_CONVERT);
40   bool AddKey(Handle<Object> key, AddKeyConversion convert = DO_NOT_CONVERT);
41   void AddKeys(Handle<FixedArray> array,
42                AddKeyConversion convert = DO_NOT_CONVERT);
43   void AddKeys(Handle<JSObject> array,
44                AddKeyConversion convert = DO_NOT_CONVERT);
45   void AddKeysFromProxy(Handle<JSObject> array);
46   Maybe<bool> AddKeysFromProxy(Handle<JSProxy> proxy, Handle<FixedArray> keys);
47   void AddElementKeysFromInterceptor(Handle<JSObject> array);
48   // Jump to the next level, pushing the current |levelLength_| to
49   // |levelLengths_| and adding a new list to |elements_|.
50   void NextPrototype();
51   // Sort the integer indices in the last list in |elements_|
52   void SortCurrentElementsList();
53   Handle<FixedArray> GetKeys(GetKeysConversion convert = KEEP_NUMBERS);
length()54   int length() { return length_; }
isolate()55   Isolate* isolate() { return isolate_; }
56 
57  private:
58   bool AddIntegerKey(uint32_t key);
59   bool AddStringKey(Handle<Object> key, AddKeyConversion convert);
60   bool AddSymbolKey(Handle<Object> array);
61   void SortCurrentElementsListRemoveDuplicates();
62 
63   Isolate* isolate_;
64   PropertyFilter filter_;
65   // |elements_| contains the sorted element keys (indices) per level.
66   std::vector<std::vector<uint32_t>*> elements_;
67   // |protoLengths_| contains the total number of keys (elements + properties)
68   // per level. Negative values mark counts for a level with keys from a proxy.
69   std::vector<int> level_lengths_;
70   // |string_properties_| contains the unique String property keys for all
71   // levels in insertion order per level.
72   Handle<OrderedHashSet> string_properties_;
73   // |symbol_properties_| contains the unique Symbol property keys for all
74   // levels in insertion order per level.
75   Handle<OrderedHashSet> symbol_properties_;
76   // |length_| keeps track of the total number of all element and property keys.
77   int length_ = 0;
78   // |levelLength_| keeps track of the number of String keys in the current
79   // level.
80   int level_string_length_ = 0;
81   // |levelSymbolLength_| keeps track of the number of Symbol keys in the
82   // current level.
83   int level_symbol_length_ = 0;
84 
85   DISALLOW_COPY_AND_ASSIGN(KeyAccumulator);
86 };
87 
88 
89 }  // namespace internal
90 }  // namespace v8
91 
92 
93 #endif  // V8_KEY_ACCUMULATOR_H_
94