1// -*- mode: c++; c-basic-offset: 4 -*-
2/*
3 * Copyright (C) 2008 Apple Inc. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
21 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
22 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#ifndef JSTypeInfo_h
28#define JSTypeInfo_h
29
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.
32
33#include "JSType.h"
34
35namespace JSC {
36
37    // WebCore uses MasqueradesAsUndefined to make document.all and style.filter undetectable.
38    static const unsigned MasqueradesAsUndefined = 1;
39    static const unsigned ImplementsHasInstance = 1 << 1;
40    static const unsigned OverridesHasInstance = 1 << 2;
41    static const unsigned ImplementsDefaultHasInstance = 1 << 3;
42    static const unsigned NeedsThisConversion = 1 << 4;
43    static const unsigned OverridesGetOwnPropertySlot = 1 << 5;
44    static const unsigned OverridesMarkChildren = 1 << 6;
45    static const unsigned OverridesGetPropertyNames = 1 << 7;
46    static const unsigned IsJSFinalObject = 1 << 8;
47
48    class TypeInfo {
49    public:
50        TypeInfo(JSType type, unsigned flags = 0)
51            : m_type(type)
52            , m_flags(flags & 0xFF)
53            , m_flags2(flags >> 8)
54        {
55            ASSERT(flags <= 0x1FF);
56            ASSERT(type <= 0xFF);
57            ASSERT(type >= CompoundType || !(flags & OverridesMarkChildren));
58            // ImplementsDefaultHasInstance means (ImplementsHasInstance & !OverridesHasInstance)
59            if ((m_flags & (ImplementsHasInstance | OverridesHasInstance)) == ImplementsHasInstance)
60                m_flags |= ImplementsDefaultHasInstance;
61        }
62
63        JSType type() const { return (JSType)m_type; }
64
65        bool masqueradesAsUndefined() const { return m_flags & MasqueradesAsUndefined; }
66        bool implementsHasInstance() const { return m_flags & ImplementsHasInstance; }
67        bool overridesHasInstance() const { return m_flags & OverridesHasInstance; }
68        bool needsThisConversion() const { return m_flags & NeedsThisConversion; }
69        bool overridesGetOwnPropertySlot() const { return m_flags & OverridesGetOwnPropertySlot; }
70        bool overridesMarkChildren() const { return m_flags & OverridesMarkChildren; }
71        bool overridesGetPropertyNames() const { return m_flags & OverridesGetPropertyNames; }
72        unsigned flags() const { return m_flags; }
73        unsigned isFinal() const { return m_flags2 && (IsJSFinalObject >> 8); }
74
75        static ptrdiff_t flagsOffset()
76        {
77            return OBJECT_OFFSETOF(TypeInfo, m_flags);
78        }
79
80        static ptrdiff_t typeOffset()
81        {
82            return OBJECT_OFFSETOF(TypeInfo, m_type);
83        }
84
85    private:
86        unsigned char m_type;
87        unsigned char m_flags;
88        unsigned char m_flags2;
89    };
90
91}
92
93#endif // JSTypeInfo_h
94