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39
40#ifndef QQMLGUARD_P_H
41#define QQMLGUARD_P_H
42
43//
44// W A R N I N G
45// -------------
46//
47// This file is not part of the Qt API. It exists for the convenience
48// of qapplication_*.cpp, qwidget*.cpp and qfiledialog.cpp. This header
49// file may change from version to version without notice, or even be removed.
50//
51// We mean it.
52//
53
54#include <QtCore/qglobal.h>
55#include <QtCore/qvariant.h>
56#include <private/qqmldata_p.h>
57
58QT_BEGIN_NAMESPACE
59
60class QQmlGuardImpl
61{
62public:
63 inline QQmlGuardImpl();
64 inline QQmlGuardImpl(QObject *);
65 inline QQmlGuardImpl(const QQmlGuardImpl &);
66 inline ~QQmlGuardImpl();
67
68 QObject *o = nullptr;
69 QQmlGuardImpl *next = nullptr;
70 QQmlGuardImpl **prev = nullptr;
71
72 inline void addGuard();
73 inline void remGuard();
74};
75
76class QObject;
77template<class T>
78class QQmlGuard : private QQmlGuardImpl
79{
80 friend class QQmlData;
81public:
82 inline QQmlGuard();
83 inline QQmlGuard(T *);
84 inline QQmlGuard(const QQmlGuard<T> &);
85 inline virtual ~QQmlGuard();
86
87 inline QQmlGuard<T> &operator=(const QQmlGuard<T> &o);
88 inline QQmlGuard<T> &operator=(T *);
89
90 inline T *object() const;
91 inline void setObject(T *g);
92
93 inline bool isNull() const
94 { return !o; }
95
96 inline T* operator->() const
97 { return static_cast<T*>(const_cast<QObject*>(o)); }
98 inline T& operator*() const
99 { return *static_cast<T*>(const_cast<QObject*>(o)); }
100 inline operator T*() const
101 { return static_cast<T*>(const_cast<QObject*>(o)); }
102 inline T* data() const
103 { return static_cast<T*>(const_cast<QObject*>(o)); }
104
105protected:
106 virtual void objectDestroyed(T *) {}
107};
108
109template <typename T>
110class QQmlStrongJSQObjectReference : public QQmlGuard<T>
111{
112public:
113 void setObject(T *o, QObject *parent) {
114 T *old = this->object();
115 if (o == old)
116 return;
117
118 if (m_jsOwnership && old && old->parent() == parent)
119 QQml_setParent_noEvent(old, nullptr);
120
121 this->QQmlGuard<T>::operator=(o);
122
123 if (o && !o->parent() && !QQmlData::keepAliveDuringGarbageCollection(o)) {
124 m_jsOwnership = true;
125 QQml_setParent_noEvent(o, parent);
126 } else {
127 m_jsOwnership = false;
128 }
129 }
130
131private:
132 using QQmlGuard<T>::setObject;
133 using QQmlGuard<T>::operator=;
134 bool m_jsOwnership = false;
135};
136
137QT_END_NAMESPACE
138
139Q_DECLARE_METATYPE(QQmlGuard<QObject>)
140
141QT_BEGIN_NAMESPACE
142
143QQmlGuardImpl::QQmlGuardImpl()
144{
145}
146
147QQmlGuardImpl::QQmlGuardImpl(QObject *g)
148: o(g)
149{
150 if (o) addGuard();
151}
152
153QQmlGuardImpl::QQmlGuardImpl(const QQmlGuardImpl &g)
154: o(g.o)
155{
156 if (o) addGuard();
157}
158
159QQmlGuardImpl::~QQmlGuardImpl()
160{
161 if (prev) remGuard();
162 o = nullptr;
163}
164
165void QQmlGuardImpl::addGuard()
166{
167 Q_ASSERT(!prev);
168
169 if (QObjectPrivate::get(o)->wasDeleted)
170 return;
171
172 QQmlData *data = QQmlData::get(o, true);
173 next = data->guards;
174 if (next) next->prev = &next;
175 data->guards = this;
176 prev = &data->guards;
177}
178
179void QQmlGuardImpl::remGuard()
180{
181 Q_ASSERT(prev);
182
183 if (next) next->prev = prev;
184 *prev = next;
185 next = nullptr;
186 prev = nullptr;
187}
188
189template<class T>
190QQmlGuard<T>::QQmlGuard()
191{
192}
193
194template<class T>
195QQmlGuard<T>::QQmlGuard(T *g)
196: QQmlGuardImpl(g)
197{
198}
199
200template<class T>
201QQmlGuard<T>::QQmlGuard(const QQmlGuard<T> &g)
202: QQmlGuardImpl(g)
203{
204}
205
206template<class T>
207QQmlGuard<T>::~QQmlGuard()
208{
209}
210
211template<class T>
212QQmlGuard<T> &QQmlGuard<T>::operator=(const QQmlGuard<T> &g)
213{
214 setObject(g.object());
215 return *this;
216}
217
218template<class T>
219QQmlGuard<T> &QQmlGuard<T>::operator=(T *g)
220{
221 setObject(g);
222 return *this;
223}
224
225template<class T>
226T *QQmlGuard<T>::object() const
227{
228 return static_cast<T *>(o);
229}
230
231template<class T>
232void QQmlGuard<T>::setObject(T *g)
233{
234 if (g != o) {
235 if (prev) remGuard();
236 o = g;
237 if (o) addGuard();
238 }
239}
240
241QT_END_NAMESPACE
242
243#endif // QQMLGUARD_P_H
244