1/****************************************************************************
2**
3** Copyright (C) 2018 The Qt Company Ltd.
4** Contact: https://www.qt.io/licensing/
5**
6** This file is part of the QtQml module of the Qt Toolkit.
7**
8** $QT_BEGIN_LICENSE:LGPL$
9** Commercial License Usage
10** Licensees holding valid commercial Qt licenses may use this file in
11** accordance with the commercial license agreement provided with the
12** Software or, alternatively, in accordance with the terms contained in
13** a written agreement between you and The Qt Company. For licensing terms
14** and conditions see https://www.qt.io/terms-conditions. For further
15** information use the contact form at https://www.qt.io/contact-us.
16**
17** GNU Lesser General Public License Usage
18** Alternatively, this file may be used under the terms of the GNU Lesser
19** General Public License version 3 as published by the Free Software
20** Foundation and appearing in the file LICENSE.LGPL3 included in the
21** packaging of this file. Please review the following information to
22** ensure the GNU Lesser General Public License version 3 requirements
23** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
24**
25** GNU General Public License Usage
26** Alternatively, this file may be used under the terms of the GNU
27** General Public License version 2.0 or (at your option) the GNU General
28** Public license version 3 or any later version approved by the KDE Free
29** Qt Foundation. The licenses are as published by the Free Software
30** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
31** included in the packaging of this file. Please review the following
32** information to ensure the GNU General Public License requirements will
33** be met: https://www.gnu.org/licenses/gpl-2.0.html and
34** https://www.gnu.org/licenses/gpl-3.0.html.
35**
36** $QT_END_LICENSE$
37**
38****************************************************************************/
39#ifndef QV4PROPERTYKEY_H
40#define QV4PROPERTYKEY_H
41
42//
43// W A R N I N G
44// -------------
45//
46// This file is not part of the Qt API. It exists purely as an
47// implementation detail. This header file may change from version to
48// version without notice, or even be removed.
49//
50// We mean it.
51//
52
53#include <private/qv4global_p.h>
54
55QT_BEGIN_NAMESPACE
56
57class QString;
58
59namespace QV4 {
60
61struct PropertyKey
62{
63private:
64 // Property keys are Strings, Symbols or unsigned integers.
65 // For convenience we derive them from Values, allowing us to store them
66 // on the JS stack
67 //
68 // They do however behave somewhat different than a Value:
69 // * If the key is a String, the pointer to the string is stored in the identifier
70 // table and thus unique.
71 // * If the key is a Symbol it simply points to the referenced symbol object
72 // * if the key is an array index (a uint < UINT_MAX), it's encoded as an
73 // integer value
74 quint64 val;
75
76 // Important: Always keep this in sync with the definitions for Integers and heap objects in Value
77 static const quint64 ArrayIndexMask = 0x3800000000000ull;
78 enum {
79 IsManagedOrUndefined_Shift = 64-15,
80 };
81 inline bool isManaged() const { return (val >> IsManagedOrUndefined_Shift) == 0; }
82 inline quint32 value() const { return val & quint64(~quint32(0)); }
83
84#if QT_POINTER_SIZE == 8
85 QML_NEARLY_ALWAYS_INLINE Heap::StringOrSymbol *m() const
86 {
87 Heap::StringOrSymbol *b;
88 memcpy(dest: &b, src: &val, n: 8);
89 return b;
90 }
91 QML_NEARLY_ALWAYS_INLINE void setM(Heap::StringOrSymbol *b)
92 {
93 memcpy(dest: &val, src: &b, n: 8);
94 }
95#elif QT_POINTER_SIZE == 4
96 QML_NEARLY_ALWAYS_INLINE Heap::StringOrSymbol *m() const
97 {
98 Q_STATIC_ASSERT(sizeof(Heap::StringOrSymbol*) == sizeof(quint32));
99 Heap::StringOrSymbol *b;
100 quint32 v = value();
101 memcpy(&b, &v, 4);
102 return b;
103 }
104 QML_NEARLY_ALWAYS_INLINE void setM(Heap::StringOrSymbol *b)
105 {
106 quint32 v;
107 memcpy(&v, &b, 4);
108 val = v;
109 }
110#endif
111
112public:
113 static PropertyKey invalid() { PropertyKey key; key.val = 0; return key; }
114 static PropertyKey fromArrayIndex(uint idx) { PropertyKey key; key.val = ArrayIndexMask | static_cast<quint64>(idx); return key; }
115 bool isStringOrSymbol() const { return isManaged() && val != 0; }
116 uint asArrayIndex() const { Q_ASSERT(isArrayIndex()); return static_cast<uint>(val & 0xffffffff); }
117 uint isArrayIndex() const { return !isManaged() && val != 0; }
118 bool isValid() const { return val != 0; }
119 static PropertyKey fromStringOrSymbol(Heap::StringOrSymbol *b)
120 { PropertyKey key; key.setM(b); return key; }
121 Heap::StringOrSymbol *asStringOrSymbol() const {
122 if (!isManaged())
123 return nullptr;
124 return m();
125 }
126
127 Q_QML_EXPORT bool isString() const;
128 bool isSymbol() const;
129 bool isCanonicalNumericIndexString() const;
130
131 Q_QML_EXPORT QString toQString() const;
132 Heap::StringOrSymbol *toStringOrSymbol(ExecutionEngine *e);
133 quint64 id() const { return val; }
134 static PropertyKey fromId(quint64 id) {
135 PropertyKey key; key.val = id; return key;
136 }
137
138 enum FunctionNamePrefix {
139 None,
140 Getter,
141 Setter
142 };
143 Heap::String *asFunctionName(ExecutionEngine *e, FunctionNamePrefix prefix) const;
144
145 bool operator ==(const PropertyKey &other) const { return val == other.val; }
146 bool operator !=(const PropertyKey &other) const { return val != other.val; }
147 bool operator <(const PropertyKey &other) const { return val < other.val; }
148};
149
150}
151
152QT_END_NAMESPACE
153
154#endif
155

source code of qtdeclarative/src/qml/jsruntime/qv4propertykey_p.h