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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#ifndef QPOINTER_H
#define QPOINTER_H
#include <QtCore/qcompare.h>
#include <QtCore/qsharedpointer.h>
#include <QtCore/qtypeinfo.h>
#ifndef QT_NO_QOBJECT
QT_BEGIN_NAMESPACE
class QVariant;
template <class T>
class QPointer
{
static_assert(!std::is_pointer<T>::value, "QPointer's template type must not be a pointer type");
template <typename X>
using if_convertible = std::enable_if_t<std::is_convertible_v<X*, T*>, bool>;
template <typename X>
friend class QPointer;
using QObjectType =
typename std::conditional<std::is_const<T>::value, const QObject, QObject>::type;
QWeakPointer<QObjectType> wp;
public:
Q_NODISCARD_CTOR
QPointer() noexcept = default;
Q_NODISCARD_CTOR
constexpr QPointer(std::nullptr_t) noexcept : QPointer{} {}
Q_WEAK_OVERLOAD
Q_NODISCARD_CTOR
inline QPointer(T *p) : wp(p, true) { }
// compiler-generated copy/move ctor/assignment operators are fine!
// compiler-generated dtor is fine!
template <typename X, if_convertible<X> = true>
Q_NODISCARD_CTOR
QPointer(QPointer<X> &&other) noexcept
: wp(std::exchange(other.wp, nullptr).internalData(), true) {}
template <typename X, if_convertible<X> = true>
Q_NODISCARD_CTOR
QPointer(const QPointer<X> &other) noexcept
: wp(other.wp.internalData(), true) {}
template <typename X, if_convertible<X> = true>
QPointer &operator=(const QPointer<X> &other) noexcept
{
QPointer(other).swap(*this);
return *this;
}
template <typename X, if_convertible<X> = true>
QPointer &operator=(QPointer<X> &&other) noexcept
{
QPointer(std::move(other)).swap(*this);
return *this;
}
#ifdef Q_QDOC
// Stop qdoc from complaining about missing function
~QPointer();
#endif
inline void swap(QPointer &other) noexcept { wp.swap(other.wp); }
inline QPointer<T> &operator=(T* p)
{ wp.assign(static_cast<QObjectType*>(p)); return *this; }
T* data() const noexcept
{ return static_cast<T*>(wp.internalData()); }
T* get() const noexcept
{ return data(); }
T* operator->() const noexcept
{ return data(); }
T& operator*() const noexcept
{ return *data(); }
operator T*() const noexcept
{ return data(); }
bool isNull() const noexcept
{ return wp.isNull(); }
explicit operator bool() const noexcept { return !isNull(); }
void clear() noexcept
{ wp.clear(); }
friend void swap(QPointer &lhs, QPointer &rhs) noexcept
{ lhs.swap(rhs); }
private:
template <typename X>
friend bool comparesEqual(const QPointer &lhs, const QPointer<X> &rhs) noexcept
{ return lhs.data() == rhs.data(); }
QT_DECLARE_EQUALITY_OPERATORS_HELPER(QPointer, QPointer<X>, /* non-constexpr */,
noexcept(true), template <typename X>)
template <typename X>
friend bool comparesEqual(const QPointer &lhs, X *rhs) noexcept
{ return lhs.data() == rhs; }
Q_DECLARE_EQUALITY_COMPARABLE(QPointer, X*, template <typename X>)
friend bool comparesEqual(const QPointer &lhs, std::nullptr_t) noexcept
{ return lhs.isNull(); }
Q_DECLARE_EQUALITY_COMPARABLE(QPointer, std::nullptr_t)
};
template <class T> Q_DECLARE_TYPEINFO_BODY(QPointer<T>, Q_RELOCATABLE_TYPE);
template<typename T>
QPointer<T>
qPointerFromVariant(const QVariant &variant)
{
const auto wp = QtSharedPointer::weakPointerFromVariant_internal(variant);
return QPointer<T>{qobject_cast<T*>(QtPrivate::EnableInternalData::internalData(wp))};
}
QT_END_NAMESPACE
#endif // QT_NO_QOBJECT
#endif // QPOINTER_H
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