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#ifndef WAITFORSIGNAL_H
#define WAITFORSIGNAL_H

#include <QObject>
#include <QTestEventLoop>

#include <utility>

// Implementation details of waitForSignal.
namespace {
    // Wraps a functor to set a flag and exit from event loop if called.
    template <class SignalHandler>
    struct waitForSignal_SignalHandlerWrapper {
        waitForSignal_SignalHandlerWrapper(SignalHandler &&sh)
            : signalHandler(std::forward<SignalHandler>(sh)) {}

        template <class... Args>
        void operator()(Args && ... args) {
            signalHandler(std::forward<Args>(args)...);
            hasBeenCalled = true;
            loop.exitLoop();
        }

        SignalHandler &&signalHandler;
        QTestEventLoop loop;
        bool hasBeenCalled = false;
    };

    // No-op functor.
    struct waitForSignal_DefaultSignalHandler {
        template <class... Args>
        void operator()(Args && ...) {}
    };
} // namespace

// Wait for a signal to be emitted.
//
// The given functor is called with the signal arguments allowing the arguments
// to be modified before returning from the signal handler (unlike QSignalSpy).
template <class Sender, class Signal, class SignalHandler>
bool waitForSignal(Sender &&sender, Signal &&signal, SignalHandler &&signalHandler, int timeout = 15000)
{
    waitForSignal_SignalHandlerWrapper<SignalHandler> signalHandlerWrapper(
        std::forward<SignalHandler>(signalHandler));
    auto connection = QObject::connect(
        std::forward<Sender>(sender),
        std::forward<Signal>(signal),
        std::ref(signalHandlerWrapper));
    signalHandlerWrapper.loop.enterLoopMSecs(timeout);
    QObject::disconnect(connection);
    return signalHandlerWrapper.hasBeenCalled;
}

template <class Sender, class Signal>
bool waitForSignal(Sender &&sender, Signal &&signal, int timeout = 15000)
{
    return waitForSignal(std::forward<Sender>(sender),
                         std::forward<Signal>(signal),
                         waitForSignal_DefaultSignalHandler(),
                         timeout);
}

#endif // !WAITFORSIGNAL_H