Add Qt libs and headers

paho-mqtt3as-proxy/Qt/include/QtCore/qnativeinterface.h

@@ -0,0 +1,148 @@
+// Copyright (C) 2021 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef QNATIVEINTERFACE_H
+#define QNATIVEINTERFACE_H
+
+#include <QtCore/qglobal.h>
+
+QT_BEGIN_NAMESPACE
+
+// We declare a virtual non-inline function in the form
+// of the destructor, making it the key function. This
+// ensures that the typeinfo of the class is exported.
+// By being protected, we also ensure that pointers to
+// the interface can't be deleted.
+#define QT_DECLARE_NATIVE_INTERFACE_3(NativeInterface, Revision, BaseType) \
+    protected: \
+        virtual ~NativeInterface(); \
+        \
+        struct TypeInfo { \
+            using baseType = BaseType; \
+            static constexpr char const *name = QT_STRINGIFY(NativeInterface); \
+            static constexpr int revision = Revision; \
+        }; \
+        \
+        template <typename, typename> \
+        friend struct QNativeInterface::Private::has_type_info; \
+        \
+        template <typename> \
+        friend bool constexpr QNativeInterface::Private::hasTypeInfo(); \
+        \
+        template <typename> \
+        friend struct QNativeInterface::Private::TypeInfo; \
+    public: \
+        NativeInterface() = default; \
+        Q_DISABLE_COPY_MOVE(NativeInterface)
+
+// Revisioned interfaces only make sense when exposed through a base
+// type via QT_DECLARE_NATIVE_INTERFACE_ACCESSOR, as the revision
+// checks happen at that level (and not for normal dynamic_casts).
+#define QT_DECLARE_NATIVE_INTERFACE_2(NativeInterface, Revision) \
+    static_assert(false, "Must provide a base type when specifying revision");
+
+#define QT_DECLARE_NATIVE_INTERFACE_1(NativeInterface) \
+    QT_DECLARE_NATIVE_INTERFACE_3(NativeInterface, 0, void)
+
+#define QT_DECLARE_NATIVE_INTERFACE(...) \
+    QT_OVERLOADED_MACRO(QT_DECLARE_NATIVE_INTERFACE, __VA_ARGS__)
+
+namespace QNativeInterface::Private {
+
+    // Basic type-trait to verify that a given native interface has
+    // all the required type information for us to evaluate it.
+    template <typename NativeInterface, typename = void>
+    struct has_type_info : std::false_type {};
+
+    // The type-trait is friended by TypeInfo, so that we can
+    // evaluate TypeInfo in the template arguments.
+    template <typename NativeInterface>
+    struct has_type_info<NativeInterface, std::void_t<
+        typename NativeInterface::TypeInfo,
+        typename NativeInterface::TypeInfo::baseType,
+        decltype(&NativeInterface::TypeInfo::name),
+        decltype(&NativeInterface::TypeInfo::revision)
+        >> : std::true_type {};
+
+    // We need to wrap the instantiation of has_type_info in a
+    // function friended by TypeInfo, otherwise MSVC will not
+    // let us evaluate TypeInfo in the template arguments.
+    template <typename NativeInterface>
+    bool constexpr hasTypeInfo()
+    {
+        return has_type_info<NativeInterface>::value;
+    }
+
+    template <typename NativeInterface>
+    struct TypeInfo
+    {
+        // To ensure SFINAE works for hasTypeInfo we can't use it in a constexpr
+        // variable that also includes an expression that relies on the type
+        // info. This helper variable is okey, as it it self contained.
+        static constexpr bool haveTypeInfo = hasTypeInfo<NativeInterface>();
+
+        // We can then use the helper variable in a constexpr condition in a
+        // function, which does not break SFINAE if haveTypeInfo is false.
+        template <typename BaseType>
+        static constexpr bool isCompatibleHelper()
+        {
+            if constexpr (haveTypeInfo)
+                return std::is_base_of<typename NativeInterface::TypeInfo::baseType, BaseType>::value;
+            else
+                return false;
+        }
+
+        // MSVC however doesn't like constexpr functions in enable_if_t conditions,
+        // so we need to wrap it yet again in a constexpr variable. This is fine,
+        // as all the SFINAE magic has been resolved at this point.
+        template <typename BaseType>
+        static constexpr bool isCompatibleWith = isCompatibleHelper<BaseType>();
+
+        // The revision and name accessors are not used in enable_if_t conditions,
+        // so we can leave them as constexpr functions. As this class template is
+        // friended by TypeInfo we can access the protected members of TypeInfo.
+        static constexpr int revision()
+        {
+            if constexpr (haveTypeInfo)
+                return NativeInterface::TypeInfo::revision;
+            else
+                return 0;
+        }
+
+        static constexpr char const *name()
+        {
+            if constexpr (haveTypeInfo)
+                return NativeInterface::TypeInfo::name;
+            else
+                return nullptr;
+        }
+    };
+
+    // Wrapper type to make the error message in case
+    // of incompatible interface types read better.
+    template <typename I>
+    struct NativeInterface : TypeInfo<I> {};
+} // QNativeInterface::Private
+
+// Declares an accessor for the native interface
+#ifdef Q_QDOC
+#define QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(T) \
+    template <typename QNativeInterface> \
+    QNativeInterface *nativeInterface() const;
+#else
+#define QT_DECLARE_NATIVE_INTERFACE_ACCESSOR(T) \
+    template <typename NativeInterface, typename TypeInfo = QNativeInterface::Private::NativeInterface<NativeInterface>, \
+    typename BaseType = T, std::enable_if_t<TypeInfo::template isCompatibleWith<T>, bool> = true> \
+    NativeInterface *nativeInterface() const \
+    { \
+        return static_cast<NativeInterface*>(resolveInterface( \
+            TypeInfo::name(), TypeInfo::revision())); \
+    } \
+    protected: \
+        void *resolveInterface(const char *name, int revision) const; \
+    public:
+#endif
+
+QT_END_NAMESPACE
+
+#endif // QNATIVEINTERFACE_H