1 // -*- mode: c++; c-basic-offset: 4 -*-
3 * Copyright (C) 2008 Apple Inc. All rights reserved.
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30 // This file would be called TypeInfo.h, but that conflicts with <typeinfo.h>
31 // in the STL on systems without case-sensitive file systems.
37 static const unsigned MasqueradesAsUndefined = 1; // WebCore uses MasqueradesAsUndefined to make document.all undetectable.
38 static const unsigned ImplementsHasInstance = 1 << 1;
39 static const unsigned OverridesHasInstance = 1 << 2;
40 static const unsigned ImplementsDefaultHasInstance = 1 << 3;
41 static const unsigned IsEnvironmentRecord = 1 << 4;
42 static const unsigned OverridesGetOwnPropertySlot = 1 << 5;
43 static const unsigned OverridesVisitChildren = 1 << 6;
44 static const unsigned OverridesGetPropertyNames = 1 << 7;
45 static const unsigned ProhibitsPropertyCaching = 1 << 8;
49 TypeInfo(JSType type, unsigned flags = 0)
51 , m_flags(flags & 0xff)
52 , m_flags2(flags >> 8)
54 ASSERT(flags <= 0x3ff);
56 ASSERT(type >= CompoundType || !(flags & OverridesVisitChildren));
57 // No object that doesn't ImplementsHasInstance should override it!
58 ASSERT((m_flags & (ImplementsHasInstance | OverridesHasInstance)) != OverridesHasInstance);
59 // ImplementsDefaultHasInstance means (ImplementsHasInstance & !OverridesHasInstance)
60 if ((m_flags & (ImplementsHasInstance | OverridesHasInstance)) == ImplementsHasInstance)
61 m_flags |= ImplementsDefaultHasInstance;
64 JSType type() const { return static_cast<JSType>(m_type); }
65 bool isObject() const { return type() >= ObjectType; }
66 bool isFinalObject() const { return type() == FinalObjectType; }
67 bool isNumberObject() const { return type() == NumberObjectType; }
69 bool masqueradesAsUndefined() const { return isSetOnFlags1(MasqueradesAsUndefined); }
70 bool implementsHasInstance() const { return isSetOnFlags1(ImplementsHasInstance); }
71 bool isEnvironmentRecord() const { return isSetOnFlags1(IsEnvironmentRecord); }
72 bool overridesHasInstance() const { return isSetOnFlags1(OverridesHasInstance); }
73 bool implementsDefaultHasInstance() const { return isSetOnFlags1(ImplementsDefaultHasInstance); }
74 bool overridesGetOwnPropertySlot() const { return isSetOnFlags1(OverridesGetOwnPropertySlot); }
75 bool overridesVisitChildren() const { return isSetOnFlags1(OverridesVisitChildren); }
76 bool overridesGetPropertyNames() const { return isSetOnFlags1(OverridesGetPropertyNames); }
77 bool prohibitsPropertyCaching() const { return isSetOnFlags2(ProhibitsPropertyCaching); }
79 static ptrdiff_t flagsOffset()
81 return OBJECT_OFFSETOF(TypeInfo, m_flags);
84 static ptrdiff_t typeOffset()
86 return OBJECT_OFFSETOF(TypeInfo, m_type);
90 bool isSetOnFlags1(unsigned flag) const { ASSERT(flag <= (1 << 7)); return m_flags & flag; }
91 bool isSetOnFlags2(unsigned flag) const { ASSERT(flag >= (1 << 8)); return m_flags2 & (flag >> 8); }
94 unsigned char m_flags;
95 unsigned char m_flags2;
100 #endif // JSTypeInfo_h