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34 #include <wtf/AlwaysInline.h>
35 #include <wtf/HashTraits.h>
39 static ALWAYS_INLINE int missingSymbolMarker() { return std::numeric_limits<int>::max(); }
41 // The bit twiddling in this class assumes that every register index is a
42 // reasonably small positive or negative number, and therefore has its high
43 // four bits all set or all unset.
45 struct SymbolTableEntry {
51 SymbolTableEntry(int index)
53 ASSERT(isValidIndex(index));
54 pack(index, false, false);
57 SymbolTableEntry(int index, unsigned attributes)
59 ASSERT(isValidIndex(index));
60 pack(index, attributes & ReadOnly, attributes & DontEnum);
70 return m_bits >> FlagBits;
73 unsigned getAttributes() const
75 unsigned attributes = 0;
76 if (m_bits & ReadOnlyFlag)
77 attributes |= ReadOnly;
78 if (m_bits & DontEnumFlag)
79 attributes |= DontEnum;
83 void setAttributes(unsigned attributes)
85 pack(getIndex(), attributes & ReadOnly, attributes & DontEnum);
88 bool isReadOnly() const
90 return m_bits & ReadOnlyFlag;
94 static const unsigned ReadOnlyFlag = 0x1;
95 static const unsigned DontEnumFlag = 0x2;
96 static const unsigned NotNullFlag = 0x4;
97 static const unsigned FlagBits = 3;
99 void pack(int index, bool readOnly, bool dontEnum)
101 m_bits = (index << FlagBits) | NotNullFlag;
103 m_bits |= ReadOnlyFlag;
105 m_bits |= DontEnumFlag;
108 bool isValidIndex(int index)
110 return ((index << FlagBits) >> FlagBits) == index;
116 struct SymbolTableIndexHashTraits : HashTraits<SymbolTableEntry> {
117 static const bool emptyValueIsZero = true;
118 static const bool needsDestruction = false;
121 typedef HashMap<RefPtr<StringImpl>, SymbolTableEntry, IdentifierRepHash, HashTraits<RefPtr<StringImpl> >, SymbolTableIndexHashTraits> SymbolTable;
123 class SharedSymbolTable : public SymbolTable, public RefCounted<SharedSymbolTable> {
124 WTF_MAKE_FAST_ALLOCATED;
126 static PassRefPtr<SharedSymbolTable> create() { return adoptRef(new SharedSymbolTable); }
128 SharedSymbolTable() { }
133 #endif // SymbolTable_h