QQmlThread: Unify postTo/callIn methods

Instead of handling member functions of different arity with dedicated
functions, simply use variadic templates and std::tuple. Moreover, move
the creation of the Message object into a dedicated helper method, so
that it can be shared between all methods.

Change-Id: I493afb2350e9cf47ea90b3532ae2a7da074d8083
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

1 files changed, 41 insertions, 181 deletions

diff --git a/src/qml/qml/ftw/qqmlthread_p.h b/src/qml/qml/ftw/qqmlthread_p.h
index 51f64ce750..4af94036b5 100644
--- a/src/qml/qml/ftw/qqmlthread_p.h
+++ b/src/qml/qml/ftw/qqmlthread_p.h
@@ -46,38 +46,22 @@ public:
     bool isThisThread() const;
 
     // Synchronously invoke a method in the thread
-    template<class O>
-    inline void callMethodInThread(void (O::*Member)());
-    template<typename T, class V, class O>
-    inline void callMethodInThread(void (O::*Member)(V), const T &);
-    template<typename T, typename T2, class V, class V2, class O>
-    inline void callMethodInThread(void (O::*Member)(V, V2), const T &, const T2 &);
+    template<typename Method, typename ...Args>
+    void callMethodInThread(Method &&method, Args &&...args);
 
     // Synchronously invoke a method in the main thread.  If the main thread is
     // blocked in a callMethodInThread() call, the call is made from within that
     // call.
-    template<class O>
-    inline void callMethodInMain(void (O::*Member)());
-    template<typename T, class V, class O>
-    inline void callMethodInMain(void (O::*Member)(V), const T &);
-    template<typename T, typename T2, class V, class V2, class O>
-    inline void callMethodInMain(void (O::*Member)(V, V2), const T &, const T2 &);
+    template<typename Method, typename ...Args>
+    void callMethodInMain(Method &&method, Args &&...args);
 
     // Asynchronously invoke a method in the thread.
-    template<class O>
-    inline void postMethodToThread(void (O::*Member)());
-    template<typename T, class V, class O>
-    inline void postMethodToThread(void (O::*Member)(V), const T &);
-    template<typename T, typename T2, class V, class V2, class O>
-    inline void postMethodToThread(void (O::*Member)(V, V2), const T &, const T2 &);
+    template<typename Method, typename ...Args>
+    void postMethodToThread(Method &&method, Args &&...args);
 
     // Asynchronously invoke a method in the main thread.
-    template<class O>
-    inline void postMethodToMain(void (O::*Member)());
-    template<typename T, class V, class O>
-    inline void postMethodToMain(void (O::*Member)(V), const T &);
-    template<typename T, typename T2, class V, class V2, class O>
-    inline void postMethodToMain(void (O::*Member)(V, V2), const T &, const T2 &);
+    template<typename Method, typename ...Args>
+    void postMethodToMain(Method &&method, Args &&...args);
 
     void waitForNextMessage();
 
@@ -90,6 +74,8 @@ private:
         Message *next;
         virtual void call(QQmlThread *) = 0;
     };
+    template<typename Method, typename ...Args>
+    Message *createMessageFromMethod(Method &&method, Args &&...args);
     void internalCallMethodInThread(Message *);
     void internalCallMethodInMain(Message *);
     void internalPostMethodToThread(Message *);
@@ -97,184 +83,58 @@ private:
     QQmlThreadPrivate *d;
 };
 
-template<class O>
-void QQmlThread::callMethodInThread(void (O::*Member)())
-{
-    struct I : public Message {
-        void (O::*Member)();
-        I(void (O::*Member)()) : Member(Member) {}
-        void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)();
-        }
-    };
-    internalCallMethodInThread(new I(Member));
-}
-
-template<typename T, class V, class O>
-void QQmlThread::callMethodInThread(void (O::*Member)(V), const T &arg)
-{
-    struct I : public Message {
-        void (O::*Member)(V);
-        T arg;
-        I(void (O::*Member)(V), const T &arg) : Member(Member), arg(arg) {}
-        void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)(arg);
-        }
-    };
-    internalCallMethodInThread(new I(Member, arg));
-}
-
-template<typename T, typename T2, class V, class V2, class O>
-void QQmlThread::callMethodInThread(void (O::*Member)(V, V2), const T &arg, const T2 &arg2)
-{
-    struct I : public Message {
-        void (O::*Member)(V, V2);
-        T arg;
-        T2 arg2;
-        I(void (O::*Member)(V, V2), const T &arg, const T2 &arg2) : Member(Member), arg(arg), arg2(arg2) {}
-        void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)(arg, arg2);
-        }
-    };
-    internalCallMethodInThread(new I(Member, arg, arg2));
-}
-
-template<class O>
-void QQmlThread::callMethodInMain(void (O::*Member)())
-{
-    struct I : public Message {
-        void (O::*Member)();
-        I(void (O::*Member)()) : Member(Member) {}
-        void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)();
-        }
-    };
-    internalCallMethodInMain(new I(Member));
-}
-
-template<typename T, class V, class O>
-void QQmlThread::callMethodInMain(void (O::*Member)(V), const T &arg)
-{
-    struct I : public Message {
-        void (O::*Member)(V);
-        T arg;
-        I(void (O::*Member)(V), const T &arg) : Member(Member), arg(arg) {}
-        void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)(arg);
-        }
-    };
-    internalCallMethodInMain(new I(Member, arg));
-}
+namespace QtPrivate {
+template <typename> struct member_function_traits;
 
-template<typename T, typename T2, class V, class V2, class O>
-void QQmlThread::callMethodInMain(void (O::*Member)(V, V2), const T &arg, const T2 &arg2)
+template <typename Return, typename Object, typename... Args>
+struct member_function_traits<Return (Object::*)(Args...)>
 {
-    struct I : public Message {
-        void (O::*Member)(V, V2);
-        T arg;
-        T2 arg2;
-        I(void (O::*Member)(V, V2), const T &arg, const T2 &arg2) : Member(Member), arg(arg), arg2(arg2) {}
-        void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)(arg, arg2);
-        }
-    };
-    internalCallMethodInMain(new I(Member, arg, arg2));
+    using class_type = Object;
+};
 }
 
-template<class O>
-void QQmlThread::postMethodToThread(void (O::*Member)())
+template<typename Method, typename ...Args>
+QQmlThread::Message *QQmlThread::createMessageFromMethod(Method &&method, Args &&...args)
 {
     struct I : public Message {
-        void (O::*Member)();
-        I(void (O::*Member)()) : Member(Member) {}
+        Method m;
+        std::tuple<std::decay_t<Args>...> arguments;
+        I(Method &&method, Args&& ...args) : m(std::forward<Method>(method)), arguments(std::forward<Args>(args)...) {}
         void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)();
+            using class_type = typename QtPrivate::member_function_traits<Method>::class_type;
+            class_type *me = static_cast<class_type *>(thread);
+            std::apply(m, std::tuple_cat(std::make_tuple(me), arguments));
         }
     };
-    internalPostMethodToThread(new I(Member));
+    return new I(std::forward<Method>(method), std::forward<Args>(args)...);
 }
 
-template<typename T, class V, class O>
-void QQmlThread::postMethodToThread(void (O::*Member)(V), const T &arg)
+template<typename Method, typename ...Args>
+void QQmlThread::callMethodInMain(Method &&method, Args&& ...args)
 {
-    struct I : public Message {
-        void (O::*Member)(V);
-        T arg;
-        I(void (O::*Member)(V), const T &arg) : Member(Member), arg(arg) {}
-        void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)(arg);
-        }
-    };
-    internalPostMethodToThread(new I(Member, arg));
+    Message *m = createMessageFromMethod(std::forward<Method>(method), std::forward<Args>(args)...);
+    internalCallMethodInMain(m);
 }
 
-template<typename T, typename T2, class V, class V2, class O>
-void QQmlThread::postMethodToThread(void (O::*Member)(V, V2), const T &arg, const T2 &arg2)
+template<typename Method, typename ...Args>
+void QQmlThread::callMethodInThread(Method &&method, Args&& ...args)
 {
-    struct I : public Message {
-        void (O::*Member)(V, V2);
-        T arg;
-        T2 arg2;
-        I(void (O::*Member)(V, V2), const T &arg, const T2 &arg2) : Member(Member), arg(arg), arg2(arg2) {}
-        void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)(arg, arg2);
-        }
-    };
-    internalPostMethodToThread(new I(Member, arg, arg2));
+    Message *m = createMessageFromMethod(std::forward<Method>(method), std::forward<Args>(args)...);
+    internalCallMethodInThread(m);
 }
 
-template<class O>
-void QQmlThread::postMethodToMain(void (O::*Member)())
+template<typename Method, typename ...Args>
+void QQmlThread::postMethodToThread(Method &&method, Args&& ...args)
 {
-    struct I : public Message {
-        void (O::*Member)();
-        I(void (O::*Member)()) : Member(Member) {}
-        void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)();
-        }
-    };
-    internalPostMethodToMain(new I(Member));
+    Message *m = createMessageFromMethod(std::forward<Method>(method), std::forward<Args>(args)...);
+    internalPostMethodToThread(m);
 }
 
-template<typename T, class V, class O>
-void QQmlThread::postMethodToMain(void (O::*Member)(V), const T &arg)
+template<typename Method, typename ...Args>
+void QQmlThread::postMethodToMain(Method &&method, Args&& ...args)
 {
-    struct I : public Message {
-        void (O::*Member)(V);
-        T arg;
-        I(void (O::*Member)(V), const T &arg) : Member(Member), arg(arg) {}
-        void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)(arg);
-        }
-    };
-    internalPostMethodToMain(new I(Member, arg));
-}
-
-template<typename T, typename T2, class V, class V2, class O>
-void QQmlThread::postMethodToMain(void (O::*Member)(V, V2), const T &arg, const T2 &arg2)
-{
-    struct I : public Message {
-        void (O::*Member)(V, V2);
-        T arg;
-        T2 arg2;
-        I(void (O::*Member)(V, V2), const T &arg, const T2 &arg2) : Member(Member), arg(arg), arg2(arg2) {}
-        void call(QQmlThread *thread) override {
-            O *me = static_cast<O *>(thread);
-            (me->*Member)(arg, arg2);
-        }
-    };
-    internalPostMethodToMain(new I(Member, arg, arg2));
+    Message *m = createMessageFromMethod(std::forward<Method>(method), std::forward<Args>(args)...);
+    internalPostMethodToMain(m);
 }
 
 QT_END_NAMESPACE