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/****************************************************************************
**
** Copyright (C) 2020 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** 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 Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** 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-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QPROMISE_H
#define QPROMISE_H
#include <QtCore/qglobal.h>
#include <QtCore/qfuture.h>
#include <utility>
QT_REQUIRE_CONFIG(future);
QT_BEGIN_NAMESPACE
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()
{
const int state = d.loadState();
// If QFutureInterface has no state, there is nothing to be done
if (state == static_cast<int>(QFutureInterfaceBase::State::NoState))
return;
// Otherwise, if computation is not finished at this point, cancel
// potential waits
if (!(state & QFutureInterfaceBase::State::Finished))
d.cancelAndFinish(); // cancel and finalize the state
}
// 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
{
qSwap(this->d, 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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