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/****************************************************************************
**
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the tools applications of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:GPL-EXCEPT$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 as published by the Free Software
** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#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 <QtCore/qglobal.h>
#include <QtCore/qsharedpointer.h>
QT_BEGIN_NAMESPACE
template<typename T>
class QDeferredFactory
{
public:
T create() const;
bool isValid() const;
};
template<typename T>
class QDeferredWeakPointer;
template<typename T>
class QDeferredSharedPointer
{
public:
using Factory = QDeferredFactory<std::remove_const_t<T>>;
QDeferredSharedPointer() = default;
QDeferredSharedPointer(QSharedPointer<T> data)
: m_data(data)
{}
QDeferredSharedPointer(QWeakPointer<T> data)
: m_data(data)
{}
QDeferredSharedPointer(QSharedPointer<T> data, QSharedPointer<Factory> factory)
: m_data(data), m_factory(factory)
{}
operator QSharedPointer<T>() const
{
lazyLoad();
return m_data;
}
operator QDeferredSharedPointer<const T>() const { return { m_data, m_factory }; }
T &operator*() const { return QSharedPointer<T>(*this).operator*(); }
T *operator->() const { return QSharedPointer<T>(*this).operator->(); }
bool isNull() const
{
lazyLoad();
return m_data.isNull();
}
explicit operator bool() const noexcept { return !isNull(); }
bool operator !() const noexcept { return isNull(); }
T *data() const { return QSharedPointer<T>(*this).data(); }
friend size_t qHash(const QDeferredSharedPointer &ptr, size_t seed = 0)
{
ptr.lazyLoad();
return qHashMulti(seed, ptr.m_factory, ptr.m_data);
}
friend bool operator==(const QDeferredSharedPointer &a, const QDeferredSharedPointer &b)
{
a.lazyLoad();
b.lazyLoad();
return a.m_factory == b.m_factory && a.m_data == b.m_data;
}
friend bool operator!=(const QDeferredSharedPointer &a, const QDeferredSharedPointer &b)
{
return !(a == b);
}
private:
friend class QDeferredWeakPointer<T>;
void lazyLoad() const
{
if (m_factory && m_factory->isValid()) {
Factory localFactory;
std::swap(localFactory, *m_factory); // Swap before executing, to avoid recursion
const_cast<std::remove_const_t<T> &>(*m_data) = localFactory.create();
}
}
QSharedPointer<T> m_data;
QSharedPointer<Factory> m_factory;
};
template<typename T>
class QDeferredWeakPointer
{
public:
using Factory = QDeferredFactory<std::remove_const_t<T>>;
QDeferredWeakPointer() = default;
QDeferredWeakPointer(const QDeferredSharedPointer<T> &strong)
: m_data(strong.m_data), m_factory(strong.m_factory)
{
}
QDeferredWeakPointer(QWeakPointer<T> data, QWeakPointer<Factory> factory)
: m_data(data), m_factory(factory)
{}
operator QWeakPointer<T>() const
{
lazyLoad();
return m_data;
}
operator QDeferredSharedPointer<T>() const
{
return QDeferredSharedPointer<T>(m_data.toStrongRef(), m_factory.toStrongRef());
}
operator QDeferredWeakPointer<const T>() const { return {m_data, m_factory}; }
QSharedPointer<T> toStrongRef() const
{
return QWeakPointer<T>(*this).toStrongRef();
}
bool isNull() const
{
lazyLoad();
return m_data.isNull();
}
explicit operator bool() const noexcept { return !isNull(); }
bool operator !() const noexcept { return isNull(); }
T *data() const { return QWeakPointer<T>(*this).data(); }
friend size_t qHash(const QDeferredWeakPointer &ptr, size_t seed = 0)
{
ptr.lazyLoad();
return qHashMulti(seed, ptr.m_factory, ptr.m_data);
}
friend bool operator==(const QDeferredWeakPointer &a, const QDeferredWeakPointer &b)
{
a.lazyLoad();
b.lazyLoad();
return a.m_factory == b.m_factory && a.m_data == b.m_data;
}
friend bool operator!=(const QDeferredWeakPointer &a, const QDeferredWeakPointer &b)
{
return !(a == b);
}
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
const_cast<std::remove_const_t<T> &>(*(m_data.toStrongRef()))
= localFactory.create();
}
}
}
QWeakPointer<T> m_data;
QWeakPointer<Factory> m_factory;
};
QT_END_NAMESPACE
#endif // QDEFERREDPOINTER_P_H
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