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// Copyright (C) 2020 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
// Qt-Security score:significant
#ifndef QDEFERREDPOINTER_P_H
#define QDEFERREDPOINTER_P_H
//
// W A R N I N G
// -------------
//
// This file is not part of the Qt API. It exists purely as an
// implementation detail. This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
#include <qtqmlcompilerexports.h>
#include <QtCore/private/qglobal_p.h>
#include <QtCore/qsharedpointer.h>
QT_BEGIN_NAMESPACE
template<typename T>
class QDeferredSharedPointer;
template<typename T>
class QDeferredWeakPointer;
template<typename U, typename F>
void resetFactoryImpl(QDeferredSharedPointer<U>&, F&&);
template<typename T>
class QDeferredFactory
{
public:
bool isValid() const;
private:
friend class QDeferredSharedPointer<const T>;
friend class QDeferredWeakPointer<const T>;
friend class QDeferredSharedPointer<T>;
friend class QDeferredWeakPointer<T>;
void populate(const QSharedPointer<T> &) const;
};
template<typename T>
class QDeferredSharedPointer
{
public:
using Factory = QDeferredFactory<std::remove_const_t<T>>;
Q_NODISCARD_CTOR QDeferredSharedPointer() = default;
Q_NODISCARD_CTOR QDeferredSharedPointer(QSharedPointer<T> data)
: m_data(std::move(data))
{}
Q_NODISCARD_CTOR QDeferredSharedPointer(QWeakPointer<T> data)
: m_data(std::move(data))
{}
Q_NODISCARD_CTOR QDeferredSharedPointer(QSharedPointer<T> data, QSharedPointer<Factory> factory)
: m_data(std::move(data)), m_factory(std::move(factory))
{
// You have to provide a valid pointer if you provide a factory. We cannot allocate the
// pointer for you because then two copies of the same QDeferredSharedPointer will diverge
// and lazy-load two separate data objects.
Q_ASSERT(!m_data.isNull() || m_factory.isNull());
}
[[nodiscard]] operator QSharedPointer<T>() const
{
lazyLoad();
return m_data;
}
operator QDeferredSharedPointer<const T>() const { return { m_data, m_factory }; }
[[nodiscard]] T &operator*() const { lazyLoad(); return m_data.operator*(); }
[[nodiscard]] T *operator->() const { lazyLoad(); return m_data.operator->(); }
bool isNull() const
{
return m_data.isNull();
}
explicit operator bool() const noexcept { return !isNull(); }
bool operator !() const noexcept { return isNull(); }
[[nodiscard]] T *data() const { lazyLoad(); return m_data.data(); }
[[nodiscard]] T *get() const { return data(); }
friend size_t qHash(const QDeferredSharedPointer &ptr, size_t seed = 0)
{
// This is a hash of the pointer, not the data.
return qHash(ptr.m_data, seed);
}
friend bool operator==(const QDeferredSharedPointer &a, const QDeferredSharedPointer &b)
{
// This is a comparison of the pointers, not their data. As we require the pointers to
// be given in the ctor, we can do this.
return a.m_data == b.m_data;
}
friend bool operator!=(const QDeferredSharedPointer &a, const QDeferredSharedPointer &b)
{
return !(a == b);
}
friend bool operator<(const QDeferredSharedPointer &a, const QDeferredSharedPointer &b)
{
return a.m_data < b.m_data;
}
friend bool operator<=(const QDeferredSharedPointer &a, const QDeferredSharedPointer &b)
{
return a.m_data <= b.m_data;
}
friend bool operator>(const QDeferredSharedPointer &a, const QDeferredSharedPointer &b)
{
return a.m_data > b.m_data;
}
friend bool operator>=(const QDeferredSharedPointer &a, const QDeferredSharedPointer &b)
{
return a.m_data >= b.m_data;
}
template <typename U>
friend bool operator==(const QDeferredSharedPointer &a, const QSharedPointer<U> &b)
{
return a.m_data == b;
}
template <typename U>
friend bool operator!=(const QDeferredSharedPointer &a, const QSharedPointer<U> &b)
{
return !(a == b);
}
template <typename U>
friend bool operator==(const QSharedPointer<U> &a, const QDeferredSharedPointer &b)
{
return b == a;
}
template <typename U>
friend bool operator!=(const QSharedPointer<U> &a, const QDeferredSharedPointer &b)
{
return b != a;
}
Factory *factory() const
{
return (m_factory && m_factory->isValid()) ? m_factory.data() : nullptr;
}
private:
friend class QDeferredWeakPointer<T>;
template<typename U, typename F>
friend void resetFactoryImpl(QDeferredSharedPointer<U>&, F&&);
void lazyLoad() const
{
if (Factory *f = factory()) {
Factory localFactory;
std::swap(localFactory, *f); // Swap before executing, to avoid recursion
localFactory.populate(m_data.template constCast<std::remove_const_t<T>>());
}
}
QSharedPointer<T> m_data;
QSharedPointer<Factory> m_factory;
};
template<typename T>
class QDeferredWeakPointer
{
public:
using Factory = QDeferredFactory<std::remove_const_t<T>>;
Q_NODISCARD_CTOR QDeferredWeakPointer() = default;
Q_NODISCARD_CTOR QDeferredWeakPointer(const QDeferredSharedPointer<T> &strong)
: m_data(strong.m_data), m_factory(strong.m_factory)
{
}
Q_NODISCARD_CTOR QDeferredWeakPointer(QWeakPointer<T> data, QWeakPointer<Factory> factory)
: m_data(data), m_factory(factory)
{}
[[nodiscard]] operator QWeakPointer<T>() const
{
lazyLoad();
return m_data;
}
[[nodiscard]] operator QDeferredSharedPointer<T>() const { return toStrongRef(); }
operator QDeferredWeakPointer<const T>() const { return {m_data, m_factory}; }
[[nodiscard]] QDeferredSharedPointer<T> toStrongRef() const
{
return QDeferredSharedPointer<T>(m_data.toStrongRef(), m_factory.toStrongRef());
}
bool isNull() const { return m_data.isNull(); }
explicit operator bool() const noexcept { return !isNull(); }
bool operator !() const noexcept { return isNull(); }
friend bool operator==(const QDeferredWeakPointer &a, const QDeferredWeakPointer &b)
{
return a.m_data == b.m_data;
}
friend bool operator!=(const QDeferredWeakPointer &a, const QDeferredWeakPointer &b)
{
return !(a == b);
}
template <typename X>
bool owner_equal(const QDeferredWeakPointer<X> &other) const noexcept
{
return m_data.owner_equal(other.m_data);
}
size_t owner_hash() const noexcept { return m_data.owner_hash(); }
private:
void lazyLoad() const
{
if (m_factory) {
auto factory = m_factory.toStrongRef();
if (factory->isValid()) {
Factory localFactory;
std::swap(localFactory, *factory); // Swap before executing, to avoid recursion
localFactory.populate(
m_data.toStrongRef().template constCast<std::remove_const_t<T>>());
}
}
}
QWeakPointer<T> m_data;
QWeakPointer<Factory> m_factory;
};
QT_END_NAMESPACE
#endif // QDEFERREDPOINTER_P_H