provider.h

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// SPDX-FileCopyrightText: Copyright (C) 2018 swift Project Community / Contributors
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-swift-pilot-client-1
 
 
#ifndef SWIFT_MISC_PROVIDER_H
#define SWIFT_MISC_PROVIDER_H
 
#include <QMetaObject>
#include <QObject>
 
#include "misc/connectionguard.h"
#include "misc/swiftmiscexport.h"
 
namespace swift::misc
{
    class SWIFT_MISC_EXPORT IProvider
    {
    public:
        virtual ~IProvider();
 
        IProvider(const IProvider &) = delete;
 
        IProvider &operator=(const IProvider &) = delete;
 
        virtual QObject *asQObject() { return nullptr; }
 
    protected:
        IProvider() {}
    };
 
    template <class PROVIDER>
    class SWIFT_MISC_EXPORT IProviderAware
    {
    protected:
        IProviderAware(PROVIDER *provider = nullptr) { this->setProvider(provider); }
 
        virtual ~IProviderAware() {}
 
        bool hasProvider() const { return m_provider; }
 
        PROVIDER *getProvider() const { return m_provider; }
 
        void setProvider(PROVIDER *provider)
        {
            if (m_provider == provider) { return; }
            if (m_provider) { m_lastProviderConnections.disconnectAll(); }
            m_provider = provider; // new provider
            IProvider *iProvider = dynamic_cast<IProvider *>(provider);
            if (iProvider && iProvider->asQObject())
            {
                QMetaObject::Connection con = QObject::connect(iProvider->asQObject(), &QObject::destroyed,
                                                               [=](QObject *obj) { this->onProviderDestroyed(obj); });
                m_lastProviderConnections.append(con);
            }
        }
 
        PROVIDER *provider() { return m_provider; }
 
        const PROVIDER *provider() const { return m_provider; }
 
    private:
        CConnectionGuard m_lastProviderConnections; 
        PROVIDER *m_provider = nullptr; 
 
        virtual void onProviderDestroyed(QObject *obj)
        {
            if (!m_provider) { return; } // already cleaned relationship
            PROVIDER *provider = qobject_cast<PROVIDER *>(obj); // provider is implemented by a QObject
            if (provider != m_provider) { return; } // not our business
            m_provider = nullptr;
        }
    };
} // namespace swift::misc
 
Q_DECLARE_INTERFACE(swift::misc::IProvider, "org.swift-project.misc.iprovider")
 
#endif // SWIFT_MISC_PROVIDER_H