microbit: Added support to remove MicroBitListener event handlers.

inc/MemberFunctionCallback.h

@@ -53,7 +53,7 @@ template <typename T>
 MemberFunctionCallback::MemberFunctionCallback(T* object, void (T::*method)(MicroBitEvent e))
 {
     this->object = object;
-    memclr(this->method, sizeof(method));
+    memclr(this->method, sizeof(this->method));
     memcpy(this->method, &method, sizeof(method));
     invoke = &MemberFunctionCallback::methodCall<T>;
 }

inc/MicroBitListener.h

@@ -54,6 +54,11 @@ struct MicroBitListener
      */
     template <typename T> 
     MicroBitListener(uint16_t id, uint16_t value, T* object, void (T::*method)(MicroBitEvent));
+
+    /**
+      * Destructor. Ensures all resources used by this listener are freed.
+      */
+    ~MicroBitListener();
 };
 
 /**

inc/MicroBitMessageBus.h

@@ -110,20 +110,116 @@ class MicroBitMessageBus : public MicroBitComponent
 	/**
 	  * Register a listener function.
 	  * 
-	  * Same as above, except the listener function is passed an extra argument in addition to the
-	  * MicroBitEvent, when called.
+	  * @param id The source of messages to listen for. Events sent from any other IDs will be filtered. 
+	  * Use MICROBIT_ID_ANY to receive events from all components.
+	  *
+	  * @param value The value of messages to listen for. Events with any other values will be filtered. 
+	  * Use MICROBIT_EVT_ANY to receive events of any value.
+	  *
+	  * @param hander The function to call when an event is received.
+	  * 
+      * Example:
+      * @code 
+      * void onButtonBClick(void *arg)
+      * {
+      * 	//do something
+      * }
+      * uBit.MessageBus.listen(MICROBIT_ID_BUTTON_B, MICROBIT_BUTTON_EVT_CLICK, onButtonBClick); // call function when ever a click event is detected.
+      * @endcode
 	  */
 	void listen(int id, int value, void (*handler)(MicroBitEvent, void*), void* arg);
 
 	/**
 	  * Register a listener function.
+	  * 
+	  * @param id The source of messages to listen for. Events sent from any other IDs will be filtered. 
+	  * Use MICROBIT_ID_ANY to receive events from all components.
+	  *
+	  * @param value The value of messages to listen for. Events with any other values will be filtered. 
+	  * Use MICROBIT_EVT_ANY to receive events of any value.
+	  *
+	  * @param hander The function to call when an event is received.
+	  * 
+      * Example:
+      * @code 
+      * void SomeClass::onButtonBClick()
+      * {
+      * 	//do something
+      * }
       *
-      * As above, but allows callbacks into member functions within a C++ object.
-      * This one is a bit more complex, but hey, that's C++ for you!
+      * SomeClass s = new SomeClass();
+      * uBit.MessageBus.listen(MICROBIT_ID_BUTTON_B, MICROBIT_BUTTON_EVT_CLICK, s, &SomeClass::onButtonBClick); 
+      * @endcode
 	  */
     template <typename T>
 	void listen(uint16_t id, uint16_t value, T* object, void (T::*handler)(MicroBitEvent));
 
+
+	/**
+	  * Unregister a listener function.
+      * Listners are identified by the Event ID, Event VALUE and handler registered using listen().
+	  * 
+	  * @param id The Event ID used to register the listener.
+	  * @param value The Event VALUE used to register the listener.
+	  * @param handler The function used to register the listener.
+      *
+	  *
+      * Example:
+      * @code 
+      * void onButtonBClick()
+      * {
+      * 	//do something
+      * }
+      *
+      * uBit.MessageBus.ignore(MICROBIT_ID_BUTTON_B, MICROBIT_BUTTON_EVT_CLICK, onButtonBClick); 
+      * @endcode
+	  */
+	void ignore(int id, int value, void (*handler)(MicroBitEvent));
+	
+	/**
+	  * Unregister a listener function.
+      * Listners are identified by the Event ID, Event VALUE and handler registered using listen().
+	  * 
+	  * @param id The Event ID used to register the listener.
+	  * @param value The Event VALUE used to register the listener.
+	  * @param handler The function used to register the listener.
+      *
+	  *
+      * Example:
+      * @code 
+      * void onButtonBClick(void *arg)
+      * {
+      * 	//do something
+      * }
+      *
+      * uBit.MessageBus.ignore(MICROBIT_ID_BUTTON_B, MICROBIT_BUTTON_EVT_CLICK, onButtonBClick); 
+      * @endcode
+	  */
+	void ignore(int id, int value, void (*handler)(MicroBitEvent, void*), void* arg);
+
+	/**
+	  * Unregister a listener function.
+      * Listners are identified by the Event ID, Event VALUE and handler registered using listen().
+	  * 
+	  * @param id The Event ID used to register the listener.
+	  * @param value The Event VALUE used to register the listener.
+	  * @param handler The function used to register the listener.
+      *
+	  *
+      * Example:
+      * @code 
+      * 
+      * void SomeClass::onButtonBClick()
+      * {
+      * 	//do something
+      * }
+      *
+      * SomeClass s = new SomeClass();
+      * uBit.MessageBus.ignore(MICROBIT_ID_BUTTON_B, MICROBIT_BUTTON_EVT_CLICK, s, &SomeClass::onButtonBClick); 
+      * @endcode
+	  */
+    template <typename T>
+	void ignore(uint16_t id, uint16_t value, T* object, void (T::*handler)(MicroBitEvent));
 	private:
 
     /**
@@ -132,6 +228,7 @@ class MicroBitMessageBus : public MicroBitComponent
      * @return 1 if the listener is valid, 0 otherwise.
      */
     int add(MicroBitListener *newListener);
+    int remove(MicroBitListener *newListener);
 
 	MicroBitListener            *listeners;		    // Chain of active listeners.
     MicroBitEventQueueItem      *evt_queue_head;    // Head of queued events to be processed.
@@ -166,13 +263,39 @@ void MicroBitMessageBus::listen(uint16_t id, uint16_t value, T* object, void (T:
 	MicroBitListener *newListener = new MicroBitListener(id, value, object, handler);
 
     if(!add(newListener))
-    {
-        delete newListener->cb_method;
         delete newListener;
-        return;
-    }
 }
 
+/**
+ * Unregister a listener function.
+ * Listners are identified by the Event ID, Event VALUE and handler registered using listen().
+ * 
+ * @param id The Event ID used to register the listener.
+ * @param value The Event VALUE used to register the listener.
+ * @param handler The function used to register the listener.
+ *
+ *
+ * Example:
+ * @code 
+ * void onButtonBClick(void *arg)
+ * {
+ * 	//do something
+ * }
+ *
+ * uBit.MessageBus.ignore(MICROBIT_ID_BUTTON_B, MICROBIT_BUTTON_EVT_CLICK, onButtonBClick); 
+ * @endcode
+ */
+template <typename T>
+void MicroBitMessageBus::ignore(uint16_t id, uint16_t value, T* object, void (T::*handler)(MicroBitEvent))
+{
+	if (handler == NULL)
+		return;
+
+	MicroBitListener listener(id, value, object, handler);
+    remove(&listener);
+}
+
+
 #endif
 
 

source/MemberFunctionCallback.cpp

@@ -26,7 +26,6 @@ void MemberFunctionCallback::fire(MicroBitEvent e)
   */
 bool MemberFunctionCallback::operator==(const MemberFunctionCallback &mfc)
 {
-    return (object == mfc.object && memcmp(method,mfc.method,sizeof(method))==0); 
+    return (object == mfc.object && (memcmp(method,mfc.method,sizeof(method))==0)); 
 }
 
-

source/MicroBitListener.cpp

@@ -43,3 +43,11 @@ MicroBitListener::MicroBitListener(uint16_t id, uint16_t value, void (*handler)(
 	this->next = NULL;
 }
 
+/**
+ * Destructor. Ensures all resources used by this listener are freed.
+ */
+MicroBitListener::~MicroBitListener()
+{
+    if(this->flags & MESSAGE_BUS_LISTENER_METHOD)
+        delete cb_method;
+}

source/MicroBitMessageBus.cpp

@@ -245,10 +245,7 @@ void MicroBitMessageBus::listen(int id, int value, void (*handler)(MicroBitEvent
 	MicroBitListener *newListener = new MicroBitListener(id, value, handler);
 
     if(!add(newListener))
-    {
         delete newListener;
-        return;
-    }
 }
 
 void MicroBitMessageBus::listen(int id, int value, void (*handler)(MicroBitEvent, void*), void* arg) 
@@ -259,10 +256,63 @@ void MicroBitMessageBus::listen(int id, int value, void (*handler)(MicroBitEvent
 	MicroBitListener *newListener = new MicroBitListener(id, value, handler, arg);
 
     if(!add(newListener))
-    {
         delete newListener;
-        return;
-    }
+}
+
+/**
+ * Unregister a listener function.
+ * Listners are identified by the Event ID, Event VALUE and handler registered using listen().
+ * 
+ * @param id The Event ID used to register the listener.
+ * @param value The Event VALUE used to register the listener.
+ * @param handler The function used to register the listener.
+ *
+ *
+ * Example:
+ * @code 
+ * void onButtonBClick()
+ * {
+ * 	//do something
+ * }
+ *
+ * uBit.MessageBus.ignore(MICROBIT_ID_BUTTON_B, MICROBIT_BUTTON_EVT_CLICK, onButtonBClick); 
+ * @endcode
+ */
+void MicroBitMessageBus::ignore(int id, int value, void (*handler)(MicroBitEvent))
+{
+	if (handler == NULL)
+		return;
+
+	MicroBitListener listener(id, value, handler);
+    remove(&listener);
+}
+
+/**
+ * Unregister a listener function.
+ * Listners are identified by the Event ID, Event VALUE and handler registered using listen().
+ * 
+ * @param id The Event ID used to register the listener.
+ * @param value The Event VALUE used to register the listener.
+ * @param handler The function used to register the listener.
+ *
+ *
+ * Example:
+ * @code 
+ * void onButtonBClick(void *arg)
+ * {
+ * 	//do something
+ * }
+ *
+ * uBit.MessageBus.ignore(MICROBIT_ID_BUTTON_B, MICROBIT_BUTTON_EVT_CLICK, onButtonBClick); 
+ * @endcode
+ */
+void MicroBitMessageBus::ignore(int id, int value, void (*handler)(MicroBitEvent, void*), void* arg)
+{
+	if (handler == NULL)
+		return;
+
+	MicroBitListener listener(id, value, handler, arg);
+    remove(&listener);
 }
 
 
@@ -280,7 +330,6 @@ int MicroBitMessageBus::add(MicroBitListener *newListener)
 	if (newListener == NULL)
 		return 0;
 
-    methodCallback = newListener->flags & MESSAGE_BUS_LISTENER_METHOD;
 
 	l = listeners;
 
@@ -291,6 +340,8 @@ int MicroBitMessageBus::add(MicroBitListener *newListener)
     // If we have a callback to a method, check the cb_method class. Otherwise, the cb function point is sufficient.
     while (l != NULL)
     {
+        methodCallback = (newListener->flags & MESSAGE_BUS_LISTENER_METHOD) && (l->flags & MESSAGE_BUS_LISTENER_METHOD);
+
         if (l->id == newListener->id && l->value == newListener->value && (methodCallback ? *l->cb_method == *newListener->cb_method : l->cb == newListener->cb))
             return 0;
 
@@ -344,3 +395,52 @@ int MicroBitMessageBus::add(MicroBitListener *newListener)
     return 1;
 }
 
+/**
+  * Remove a MicroBitListener from the list that matches the given listener.
+  * @param listener The MicroBitListener to validate.
+  * @return The number of listeners removed from the list.
+  */
+int MicroBitMessageBus::remove(MicroBitListener *listener)
+{
+	MicroBitListener *l, *p;
+    int removed = 0;
+
+	//handler can't be NULL!
+	if (listener == NULL)
+		return 0;
+
+	l = listeners;
+	p = NULL;
+
+    // Walk this list of event handlers. Delete any that match the given listener.
+    while (l != NULL)
+    {
+        if (l->id == listener->id && l->value == listener->value && ((listener->flags & MESSAGE_BUS_LISTENER_METHOD) == (l->flags & MESSAGE_BUS_LISTENER_METHOD)))
+        {
+            if(((listener->flags & MESSAGE_BUS_LISTENER_METHOD) && (*l->cb_method == *listener->cb_method)) || 
+              ((!(listener->flags & MESSAGE_BUS_LISTENER_METHOD) && l->cb == listener->cb)))
+            {
+                // Found a match. Remove from the list.
+                if (p == NULL)
+                    listeners = l->next;
+                else 
+                    p->next = l->next;
+
+                // delete the listener.
+                MicroBitListener *t = l;
+                l = l->next;
+
+                delete t;
+                removed++;
+
+                continue;
+            }
+        }
+
+        p = l;
+        l = l->next;
+    }
+
+    return removed;
+}
+