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/****************************************************************************
**
** Copyright (C) 2022 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:COMM$
**
** 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.
**
** $QT_END_LICENSE$
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
**
******************************************************************************/
#ifndef QPROMISE_H
#define QPROMISE_H
#include <QtCore/qglobal.h>
#include <QtCore/qfutureinterface.h>
#include <utility>
QT_REQUIRE_CONFIG(future);
QT_BEGIN_NAMESPACE
namespace QtPrivate {
template<class T, class U>
using EnableIfSameOrConvertible = std::enable_if_t<std::is_convertible_v<T, U>>;
} // namespace QtPrivate
template<typename T>
class QPromise
{
static_assert (std::is_move_constructible_v<T>
|| std::is_same_v<T, void>,
"A move-constructible type or type void is required");
public:
QPromise() = default;
Q_DISABLE_COPY(QPromise)
QPromise(QPromise<T> &&other) = default;
QPromise(const QFutureInterface<T> &other) : d(other) {}
QPromise(QFutureInterface<T> &&other) noexcept : d(std::move(other)) {}
QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_MOVE_AND_SWAP(QPromise)
~QPromise()
{
// If computation is not finished at this point, cancel
// potential waits
if (d.d && !(d.loadState() & QFutureInterfaceBase::State::Finished)) {
d.cancel();
finish(); // required to finalize the state
d.cleanContinuation();
}
}
// Core QPromise APIs
QFuture<T> future() const { return d.future(); }
template<typename U, typename = QtPrivate::EnableIfSameOrConvertible<U, T>>
bool addResult(U &&result, int index = -1)
{
return d.reportResult(std::forward<U>(result), index);
}
#ifndef QT_NO_EXCEPTIONS
void setException(const QException &e) { d.reportException(e); }
#if QT_VERSION < QT_VERSION_CHECK(7, 0, 0)
void setException(std::exception_ptr e) { d.reportException(e); }
#else
void setException(const std::exception_ptr &e) { d.reportException(e); }
#endif
#endif
void start() { d.reportStarted(); }
void finish() { d.reportFinished(); }
void suspendIfRequested() { d.suspendIfRequested(); }
bool isCanceled() const { return d.isCanceled(); }
// Progress methods
void setProgressRange(int minimum, int maximum) { d.setProgressRange(minimum, maximum); }
void setProgressValue(int progressValue) { d.setProgressValue(progressValue); }
void setProgressValueAndText(int progressValue, const QString &progressText)
{
d.setProgressValueAndText(progressValue, progressText);
}
void swap(QPromise<T> &other) noexcept
{
d.swap(other.d);
}
#if defined(Q_CLANG_QDOC) // documentation-only simplified signatures
bool addResult(const T &result, int index = -1) { }
bool addResult(T &&result, int index = -1) { }
#endif
private:
mutable QFutureInterface<T> d;
};
template<typename T>
inline void swap(QPromise<T> &a, QPromise<T> &b) noexcept
{
a.swap(b);
}
QT_END_NAMESPACE
#endif // QPROMISE_H
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