QObject: allow connecting to functors with a receiver object

Up to now, it was only possible to connect to functors in a direct
way, without being capable of using Qt::ConnectionType. This patch
allows for specifying a receiver for Functors and function
pointers, hence making it possible to specify effectively the
connection type.

To do this properly, it was needed to add an enum in FunctionPointer
representing whether the considered function is a member function
or not, to reduce ambiguity upon overloaded calls.

Moreover, now senders are checked for the existence of a slot obj
as well. This way, should the context be freed, the slot obj and
the functor contained in it will be freed as well.

On a side note, connecting to a static slot
(like QCoreApplication::quit) specifying the receiver object is
now compiling.

Change-Id: I46474099413b1dc6ca4db9934191d469baeef070
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

1 files changed, 35 insertions, 6 deletions

diff --git a/src/corelib/kernel/qobject.h b/src/corelib/kernel/qobject.h
index 15b9c8f35e..e2000afc82 100644
--- a/src/corelib/kernel/qobject.h
+++ b/src/corelib/kernel/qobject.h
@@ -208,6 +208,7 @@ public:
 #ifdef Q_QDOC
     static QMetaObject::Connection connect(const QObject *sender, PointerToMemberFunction signal, const QObject *receiver, PointerToMemberFunction method, Qt::ConnectionType type);
     static QMetaObject::Connection connect(const QObject *sender, PointerToMemberFunction signal, Functor functor);
+    static QMetaObject::Connection connect(const QObject *sender, PointerToMemberFunction signal, const QObject *context, Functor functor, Qt::ConnectionType type);
 #else
     //Connect a signal to a pointer to qobject member function
     template <typename Func1, typename Func2>
@@ -245,6 +246,16 @@ public:
     static inline typename QtPrivate::QEnableIf<int(QtPrivate::FunctionPointer<Func2>::ArgumentCount) >= 0, QMetaObject::Connection>::Type
             connect(const typename QtPrivate::FunctionPointer<Func1>::Object *sender, Func1 signal, Func2 slot)
     {
+        return connect(sender, signal, sender, slot, Qt::DirectConnection);
+    }
+
+    //connect to a function pointer  (not a member)
+    template <typename Func1, typename Func2>
+    static inline typename QtPrivate::QEnableIf<int(QtPrivate::FunctionPointer<Func2>::ArgumentCount) >= 0 &&
+                                                !QtPrivate::FunctionPointer<Func2>::IsPointerToMemberFunction, QMetaObject::Connection>::Type
+            connect(const typename QtPrivate::FunctionPointer<Func1>::Object *sender, Func1 signal, const QObject *context, Func2 slot,
+                    Qt::ConnectionType type = Qt::AutoConnection)
+    {
         typedef QtPrivate::FunctionPointer<Func1> SignalType;
         typedef QtPrivate::FunctionPointer<Func2> SlotType;
 
@@ -259,11 +270,15 @@ public:
         Q_STATIC_ASSERT_X((QtPrivate::AreArgumentsCompatible<typename SlotType::ReturnType, typename SignalType::ReturnType>::value),
                           "Return type of the slot is not compatible with the return type of the signal.");
 
-        return connectImpl(sender, reinterpret_cast<void **>(&signal), sender, 0,
+        const int *types = 0;
+        if (type == Qt::QueuedConnection || type == Qt::BlockingQueuedConnection)
+            types = QtPrivate::ConnectionTypes<typename SignalType::Arguments>::types();
+
+        return connectImpl(sender, reinterpret_cast<void **>(&signal), context, 0,
                            new QtPrivate::QStaticSlotObject<Func2,
                                                  typename QtPrivate::List_Left<typename SignalType::Arguments, SlotType::ArgumentCount>::Value,
                                                  typename SignalType::ReturnType>(slot),
-                           Qt::DirectConnection, 0, &SignalType::Object::staticMetaObject);
+                           type, types, &SignalType::Object::staticMetaObject);
     }
 
     //connect to a functor
@@ -271,6 +286,15 @@ public:
     static inline typename QtPrivate::QEnableIf<QtPrivate::FunctionPointer<Func2>::ArgumentCount == -1, QMetaObject::Connection>::Type
             connect(const typename QtPrivate::FunctionPointer<Func1>::Object *sender, Func1 signal, Func2 slot)
     {
+        return connect(sender, signal, sender, slot, Qt::DirectConnection);
+    }
+
+    //connect to a functor, with a "context" object defining in which event loop is going to be executed
+    template <typename Func1, typename Func2>
+    static inline typename QtPrivate::QEnableIf<QtPrivate::FunctionPointer<Func2>::ArgumentCount == -1, QMetaObject::Connection>::Type
+            connect(const typename QtPrivate::FunctionPointer<Func1>::Object *sender, Func1 signal, const QObject *context, Func2 slot,
+                    Qt::ConnectionType type = Qt::AutoConnection)
+    {
 #if defined (Q_COMPILER_DECLTYPE) && defined (Q_COMPILER_VARIADIC_TEMPLATES)
         typedef QtPrivate::FunctionPointer<Func1> SignalType;
         const int FunctorArgumentCount = QtPrivate::ComputeFunctorArgumentCount<Func2 , typename SignalType::Arguments>::Value;
@@ -292,9 +316,10 @@ public:
         C++11 variadic templates
       */
 #ifndef Q_COMPILER_DECLTYPE  //Workaround the lack of decltype using another function as indirection
-        return connect_functor(sender, signal, slot, &Func2::operator()); }
+        return connect_functor(sender, signal, context, slot, &Func2::operator(), type); }
     template <typename Func1, typename Func2, typename Func2Operator>
-    static inline QMetaObject::Connection connect_functor(const QObject *sender, Func1 signal, Func2 slot, Func2Operator) {
+    static inline QMetaObject::Connection connect_functor(const QObject *sender, Func1 signal, const QObject *context,
+                                                          Func2 slot, Func2Operator, Qt::ConnectionType type) {
         typedef QtPrivate::FunctionPointer<Func2Operator> SlotType ;
 #else
         typedef QtPrivate::FunctionPointer<decltype(&Func2::operator())> SlotType ;
@@ -315,11 +340,15 @@ public:
         Q_STATIC_ASSERT_X(QtPrivate::HasQ_OBJECT_Macro<typename SignalType::Object>::Value,
                           "No Q_OBJECT in the class with the signal");
 
-        return connectImpl(sender, reinterpret_cast<void **>(&signal), sender, 0,
+        const int *types = 0;
+        if (type == Qt::QueuedConnection || type == Qt::BlockingQueuedConnection)
+            types = QtPrivate::ConnectionTypes<typename SignalType::Arguments>::types();
+
+        return connectImpl(sender, reinterpret_cast<void **>(&signal), context, 0,
                            new QtPrivate::QFunctorSlotObject<Func2, SlotArgumentCount,
                                 typename QtPrivate::List_Left<typename SignalType::Arguments, SlotArgumentCount>::Value,
                                 typename SignalType::ReturnType>(slot),
-                           Qt::DirectConnection, 0, &SignalType::Object::staticMetaObject);
+                           type, types, &SignalType::Object::staticMetaObject);
     }
 #endif //Q_QDOC