1 // Copyright 2017 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_OBJECTS_STRING_TABLE_H_
6 #define V8_OBJECTS_STRING_TABLE_H_
7 
8 #include "src/objects/hash-table.h"
9 
10 // Has to be the last include (doesn't have include guards):
11 #include "src/objects/object-macros.h"
12 
13 namespace v8 {
14 namespace internal {
15 
16 class StringTableKey : public HashTableKey {
17  public:
18   explicit inline StringTableKey(uint32_t hash_field);
19 
20   virtual Handle<String> AsHandle(Isolate* isolate) = 0;
HashField()21   uint32_t HashField() const {
22     DCHECK_NE(0, hash_field_);
23     return hash_field_;
24   }
25 
26  protected:
27   inline void set_hash_field(uint32_t hash_field);
28 
29  private:
30   uint32_t hash_field_ = 0;
31 };
32 
33 class StringTableShape : public BaseShape<StringTableKey*> {
34  public:
IsMatch(Key key,Object * value)35   static inline bool IsMatch(Key key, Object* value) {
36     return key->IsMatch(value);
37   }
38 
Hash(Isolate * isolate,Key key)39   static inline uint32_t Hash(Isolate* isolate, Key key) { return key->Hash(); }
40 
41   static inline uint32_t HashForObject(Isolate* isolate, Object* object);
42 
43   static inline Handle<Object> AsHandle(Isolate* isolate, Key key);
44 
45   static inline int GetMapRootIndex();
46 
47   static const int kPrefixSize = 0;
48   static const int kEntrySize = 1;
49 };
50 
51 class SeqOneByteString;
52 
53 // StringTable.
54 //
55 // No special elements in the prefix and the element size is 1
56 // because only the string itself (the key) needs to be stored.
57 class StringTable : public HashTable<StringTable, StringTableShape> {
58  public:
59   // Find string in the string table. If it is not there yet, it is
60   // added. The return value is the string found.
61   V8_EXPORT_PRIVATE static Handle<String> LookupString(Isolate* isolate,
62                                                        Handle<String> key);
63   static Handle<String> LookupKey(Isolate* isolate, StringTableKey* key);
64   static Handle<String> AddKeyNoResize(Isolate* isolate, StringTableKey* key);
65   static String* ForwardStringIfExists(Isolate* isolate, StringTableKey* key,
66                                        String* string);
67 
68   // Shink the StringTable if it's very empty (kMaxEmptyFactor) to avoid the
69   // performance overhead of re-allocating the StringTable over and over again.
70   static Handle<StringTable> CautiousShrink(Isolate* isolate,
71                                             Handle<StringTable> table);
72 
73   // Looks up a string that is equal to the given string and returns
74   // string handle if it is found, or an empty handle otherwise.
75   V8_WARN_UNUSED_RESULT static MaybeHandle<String> LookupTwoCharsStringIfExists(
76       Isolate* isolate, uint16_t c1, uint16_t c2);
77   static Object* LookupStringIfExists_NoAllocate(Isolate* isolate,
78                                                  String* string);
79 
80   static void EnsureCapacityForDeserialization(Isolate* isolate, int expected);
81 
82   DECL_CAST(StringTable)
83 
84   static const int kMaxEmptyFactor = 4;
85   static const int kMinCapacity = 2048;
86   static const int kMinShrinkCapacity = kMinCapacity;
87 
88  private:
89   template <bool seq_one_byte>
90   friend class JsonParser;
91 
92   DISALLOW_IMPLICIT_CONSTRUCTORS(StringTable);
93 };
94 
95 class StringSetShape : public BaseShape<String*> {
96  public:
97   static inline bool IsMatch(String* key, Object* value);
98   static inline uint32_t Hash(Isolate* isolate, String* key);
99   static inline uint32_t HashForObject(Isolate* isolate, Object* object);
100 
101   static const int kPrefixSize = 0;
102   static const int kEntrySize = 1;
103 };
104 
105 class StringSet : public HashTable<StringSet, StringSetShape> {
106  public:
107   static Handle<StringSet> New(Isolate* isolate);
108   static Handle<StringSet> Add(Isolate* isolate, Handle<StringSet> blacklist,
109                                Handle<String> name);
110   bool Has(Isolate* isolate, Handle<String> name);
111 
112   DECL_CAST(StringSet)
113 };
114 
115 }  // namespace internal
116 }  // namespace v8
117 
118 #include "src/objects/object-macros-undef.h"
119 
120 #endif  // V8_OBJECTS_STRING_TABLE_H_
121