1// Copyright (C) 2016 The Qt Company Ltd.
2// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
3
4#ifndef QPOINTER_H
5#define QPOINTER_H
6
7#include <QtCore/qsharedpointer.h>
8#include <QtCore/qtypeinfo.h>
9
10#ifndef QT_NO_QOBJECT
11
12QT_BEGIN_NAMESPACE
13
14class QVariant;
15
16template <class T>
17class QPointer
18{
19 static_assert(!std::is_pointer<T>::value, "QPointer's template type must not be a pointer type");
20
21 template <typename X>
22 using if_convertible = std::enable_if_t<std::is_convertible_v<X*, T*>, bool>;
23 template <typename X>
24 friend class QPointer;
25
26 using QObjectType =
27 typename std::conditional<std::is_const<T>::value, const QObject, QObject>::type;
28 QWeakPointer<QObjectType> wp;
29public:
30 Q_NODISCARD_CTOR
31 QPointer() noexcept = default;
32 Q_NODISCARD_CTOR
33 constexpr QPointer(std::nullptr_t) noexcept : QPointer{} {}
34 Q_WEAK_OVERLOAD
35 Q_NODISCARD_CTOR
36 inline QPointer(T *p) : wp(p, true) { }
37 // compiler-generated copy/move ctor/assignment operators are fine!
38 // compiler-generated dtor is fine!
39
40 template <typename X, if_convertible<X> = true>
41 Q_NODISCARD_CTOR
42 QPointer(QPointer<X> &&other) noexcept
43 : wp(std::exchange(other.wp, nullptr).internalData(), true) {}
44 template <typename X, if_convertible<X> = true>
45 Q_NODISCARD_CTOR
46 QPointer(const QPointer<X> &other) noexcept
47 : wp(other.wp.internalData(), true) {}
48
49 template <typename X, if_convertible<X> = true>
50 QPointer &operator=(const QPointer<X> &other) noexcept
51 {
52 QPointer(other).swap(*this);
53 return *this;
54 }
55
56 template <typename X, if_convertible<X> = true>
57 QPointer &operator=(QPointer<X> &&other) noexcept
58 {
59 QPointer(std::move(other)).swap(*this);
60 return *this;
61 }
62
63#ifdef Q_QDOC
64 // Stop qdoc from complaining about missing function
65 ~QPointer();
66#endif
67
68 inline void swap(QPointer &other) noexcept { wp.swap(other.wp); }
69
70 inline QPointer<T> &operator=(T* p)
71 { wp.assign(static_cast<QObjectType*>(p)); return *this; }
72
73 T* data() const noexcept
74 { return static_cast<T*>(wp.internalData()); }
75 T* get() const noexcept
76 { return data(); }
77 T* operator->() const noexcept
78 { return data(); }
79 T& operator*() const noexcept
80 { return *data(); }
81 operator T*() const noexcept
82 { return data(); }
83
84 bool isNull() const noexcept
85 { return wp.isNull(); }
86
87 void clear() noexcept
88 { wp.clear(); }
89
90 friend void swap(QPointer &lhs, QPointer &rhs) noexcept
91 { lhs.swap(rhs); }
92
93#define DECLARE_COMPARE_SET(T1, A1, T2, A2) \
94 friend bool operator==(T1, T2) noexcept \
95 { return A1 == A2; } \
96 friend bool operator!=(T1, T2) noexcept \
97 { return A1 != A2; }
98
99#define DECLARE_TEMPLATE_COMPARE_SET(T1, A1, T2, A2) \
100 template <typename X> \
101 friend bool operator==(T1, T2) noexcept \
102 { return A1 == A2; } \
103 template <typename X> \
104 friend bool operator!=(T1, T2) noexcept \
105 { return A1 != A2; }
106
107 DECLARE_TEMPLATE_COMPARE_SET(const QPointer &p1, p1.data(), const QPointer<X> &p2, p2.data())
108 DECLARE_TEMPLATE_COMPARE_SET(const QPointer &p1, p1.data(), X *ptr, ptr)
109 DECLARE_TEMPLATE_COMPARE_SET(X *ptr, ptr, const QPointer &p2, p2.data())
110 DECLARE_COMPARE_SET(const QPointer &p1, p1.data(), std::nullptr_t, nullptr)
111 DECLARE_COMPARE_SET(std::nullptr_t, nullptr, const QPointer &p2, p2.data())
112#undef DECLARE_COMPARE_SET
113#undef DECLARE_TEMPLATE_COMPARE_SET
114};
115template <class T> Q_DECLARE_TYPEINFO_BODY(QPointer<T>, Q_RELOCATABLE_TYPE);
116
117template<typename T>
118QPointer<T>
119qPointerFromVariant(const QVariant &variant)
120{
121 const auto wp = QtSharedPointer::weakPointerFromVariant_internal(variant);
122 return QPointer<T>{qobject_cast<T*>(QtPrivate::EnableInternalData::internalData(p: wp))};
123}
124
125QT_END_NAMESPACE
126
127#endif // QT_NO_QOBJECT
128
129#endif // QPOINTER_H
130