Updated minor functionality of the Callback class

- Marked `call` and `operator()` functions as const
- Moved to static_cast for internal function pointer to avoid losing
  compiler checked const-safety
- Added test for `operator=` with non-callback types
- Moved from zero-cast to value-initializer when callback is null
- Added `operator==` and `operator!=`
- Removed special handling of null callback
- Replicated doxygen to all overloads
- Added correct nops where uninitialized callbacks are called
- Added assertion for null callback
- Removed copy-constructor from callback constructor

TESTS/mbed_drivers/callback/main.cpp

@@ -203,20 +203,14 @@ void test_dispatch0() {
     Verifier<T>::verify0((volatile Thing<T>*)&thing, &volatile_func0<T>);
     Verifier<T>::verify0((const volatile Thing<T>*)&thing, &const_volatile_func0<T>);
     Verifier<T>::verify0(callback(static_func0<T>));
-    Verifier<T>::verify0(callback(&thing, &Thing<T>::member_func0));
-    Verifier<T>::verify0(callback((const Thing<T>*)&thing, &Thing<T>::const_member_func0));
-    Verifier<T>::verify0(callback((volatile Thing<T>*)&thing, &Thing<T>::volatile_member_func0));
-    Verifier<T>::verify0(callback((const volatile Thing<T>*)&thing, &Thing<T>::const_volatile_member_func0));
-    Verifier<T>::verify0(callback(&thing, &bound_func0<T>));
-    Verifier<T>::verify0(callback((const Thing<T>*)&thing, &const_func0<T>));
-    Verifier<T>::verify0(callback((volatile Thing<T>*)&thing, &volatile_func0<T>));
-    Verifier<T>::verify0(callback((const volatile Thing<T>*)&thing, &const_volatile_func0<T>));
 
-    Callback<T()> callback(static_func0);
-    Verifier<T>::verify0(callback);
-    callback.attach(&thing, &bound_func0<T>);
-    Verifier<T>::verify0(&callback, &Callback<T()>::call);
-    Verifier<T>::verify0((void*)&callback, &Callback<T()>::thunk);
+    Callback<T()> cb(static_func0);
+    Verifier<T>::verify0(cb);
+    cb = static_func0;
+    Verifier<T>::verify0(cb);
+    cb.attach(&thing, &bound_func0<T>);
+    Verifier<T>::verify0(&cb, &Callback<T()>::call);
+    Verifier<T>::verify0((void*)&cb, &Callback<T()>::thunk);
 }
 
 template <typename T>
@@ -232,20 +226,14 @@ void test_dispatch1() {
     Verifier<T>::verify1((volatile Thing<T>*)&thing, &volatile_func1<T>);
     Verifier<T>::verify1((const volatile Thing<T>*)&thing, &const_volatile_func1<T>);
     Verifier<T>::verify1(callback(static_func1<T>));
-    Verifier<T>::verify1(callback(&thing, &Thing<T>::member_func1));
-    Verifier<T>::verify1(callback((const Thing<T>*)&thing, &Thing<T>::const_member_func1));
-    Verifier<T>::verify1(callback((volatile Thing<T>*)&thing, &Thing<T>::volatile_member_func1));
-    Verifier<T>::verify1(callback((const volatile Thing<T>*)&thing, &Thing<T>::const_volatile_member_func1));
-    Verifier<T>::verify1(callback(&thing, &bound_func1<T>));
-    Verifier<T>::verify1(callback((const Thing<T>*)&thing, &const_func1<T>));
-    Verifier<T>::verify1(callback((volatile Thing<T>*)&thing, &volatile_func1<T>));
-    Verifier<T>::verify1(callback((const volatile Thing<T>*)&thing, &const_volatile_func1<T>));
 
-    Callback<T(T)> callback(static_func1);
-    Verifier<T>::verify1(callback);
-    callback.attach(&thing, &bound_func1<T>);
-    Verifier<T>::verify1(&callback, &Callback<T(T)>::call);
-    Verifier<T>::verify1((void*)&callback, &Callback<T(T)>::thunk);
+    Callback<T(T)> cb(static_func1);
+    Verifier<T>::verify1(cb);
+    cb = static_func1;
+    Verifier<T>::verify1(cb);
+    cb.attach(&thing, &bound_func1<T>);
+    Verifier<T>::verify1(&cb, &Callback<T(T)>::call);
+    Verifier<T>::verify1((void*)&cb, &Callback<T(T)>::thunk);
 }
 
 template <typename T>
@@ -261,20 +249,14 @@ void test_dispatch2() {
     Verifier<T>::verify2((volatile Thing<T>*)&thing, &volatile_func2<T>);
     Verifier<T>::verify2((const volatile Thing<T>*)&thing, &const_volatile_func2<T>);
     Verifier<T>::verify2(callback(static_func2<T>));
-    Verifier<T>::verify2(callback(&thing, &Thing<T>::member_func2));
-    Verifier<T>::verify2(callback((const Thing<T>*)&thing, &Thing<T>::const_member_func2));
-    Verifier<T>::verify2(callback((volatile Thing<T>*)&thing, &Thing<T>::volatile_member_func2));
-    Verifier<T>::verify2(callback((const volatile Thing<T>*)&thing, &Thing<T>::const_volatile_member_func2));
-    Verifier<T>::verify2(callback(&thing, &bound_func2<T>));
-    Verifier<T>::verify2(callback((const Thing<T>*)&thing, &const_func2<T>));
-    Verifier<T>::verify2(callback((volatile Thing<T>*)&thing, &volatile_func2<T>));
-    Verifier<T>::verify2(callback((const volatile Thing<T>*)&thing, &const_volatile_func2<T>));
 
-    Callback<T(T, T)> callback(static_func2);
-    Verifier<T>::verify2(callback);
-    callback.attach(&thing, &bound_func2<T>);
-    Verifier<T>::verify2(&callback, &Callback<T(T, T)>::call);
-    Verifier<T>::verify2((void*)&callback, &Callback<T(T, T)>::thunk);
+    Callback<T(T, T)> cb(static_func2);
+    Verifier<T>::verify2(cb);
+    cb = static_func2;
+    Verifier<T>::verify2(cb);
+    cb.attach(&thing, &bound_func2<T>);
+    Verifier<T>::verify2(&cb, &Callback<T(T, T)>::call);
+    Verifier<T>::verify2((void*)&cb, &Callback<T(T, T)>::thunk);
 }
 
 template <typename T>
@@ -290,20 +272,14 @@ void test_dispatch3() {
     Verifier<T>::verify3((volatile Thing<T>*)&thing, &volatile_func3<T>);
     Verifier<T>::verify3((const volatile Thing<T>*)&thing, &const_volatile_func3<T>);
     Verifier<T>::verify3(callback(static_func3<T>));
-    Verifier<T>::verify3(callback(&thing, &Thing<T>::member_func3));
-    Verifier<T>::verify3(callback((const Thing<T>*)&thing, &Thing<T>::const_member_func3));
-    Verifier<T>::verify3(callback((volatile Thing<T>*)&thing, &Thing<T>::volatile_member_func3));
-    Verifier<T>::verify3(callback((const volatile Thing<T>*)&thing, &Thing<T>::const_volatile_member_func3));
-    Verifier<T>::verify3(callback(&thing, &bound_func3<T>));
-    Verifier<T>::verify3(callback((const Thing<T>*)&thing, &const_func3<T>));
-    Verifier<T>::verify3(callback((volatile Thing<T>*)&thing, &volatile_func3<T>));
-    Verifier<T>::verify3(callback((const volatile Thing<T>*)&thing, &const_volatile_func3<T>));
 
-    Callback<T(T, T, T)> callback(static_func3);
-    Verifier<T>::verify3(callback);
-    callback.attach(&thing, &bound_func3<T>);
-    Verifier<T>::verify3(&callback, &Callback<T(T, T, T)>::call);
-    Verifier<T>::verify3((void*)&callback, &Callback<T(T, T, T)>::thunk);
+    Callback<T(T, T, T)> cb(static_func3);
+    Verifier<T>::verify3(cb);
+    cb = static_func3;
+    Verifier<T>::verify3(cb);
+    cb.attach(&thing, &bound_func3<T>);
+    Verifier<T>::verify3(&cb, &Callback<T(T, T, T)>::call);
+    Verifier<T>::verify3((void*)&cb, &Callback<T(T, T, T)>::thunk);
 }
 
 template <typename T>
@@ -319,20 +295,14 @@ void test_dispatch4() {
     Verifier<T>::verify4((volatile Thing<T>*)&thing, &volatile_func4<T>);
     Verifier<T>::verify4((const volatile Thing<T>*)&thing, &const_volatile_func4<T>);
     Verifier<T>::verify4(callback(static_func4<T>));
-    Verifier<T>::verify4(callback(&thing, &Thing<T>::member_func4));
-    Verifier<T>::verify4(callback((const Thing<T>*)&thing, &Thing<T>::const_member_func4));
-    Verifier<T>::verify4(callback((volatile Thing<T>*)&thing, &Thing<T>::volatile_member_func4));
-    Verifier<T>::verify4(callback((const volatile Thing<T>*)&thing, &Thing<T>::const_volatile_member_func4));
-    Verifier<T>::verify4(callback(&thing, &bound_func4<T>));
-    Verifier<T>::verify4(callback((const Thing<T>*)&thing, &const_func4<T>));
-    Verifier<T>::verify4(callback((volatile Thing<T>*)&thing, &volatile_func4<T>));
-    Verifier<T>::verify4(callback((const volatile Thing<T>*)&thing, &const_volatile_func4<T>));
 
-    Callback<T(T, T, T, T)> callback(static_func4);
-    Verifier<T>::verify4(callback);
-    callback.attach(&thing, &bound_func4<T>);
-    Verifier<T>::verify4(&callback, &Callback<T(T, T, T, T)>::call);
-    Verifier<T>::verify4((void*)&callback, &Callback<T(T, T, T, T)>::thunk);
+    Callback<T(T, T, T, T)> cb(static_func4);
+    Verifier<T>::verify4(cb);
+    cb = static_func4;
+    Verifier<T>::verify4(cb);
+    cb.attach(&thing, &bound_func4<T>);
+    Verifier<T>::verify4(&cb, &Callback<T(T, T, T, T)>::call);
+    Verifier<T>::verify4((void*)&cb, &Callback<T(T, T, T, T)>::thunk);
 }
 
 template <typename T>
@@ -348,20 +318,14 @@ void test_dispatch5() {
     Verifier<T>::verify5((volatile Thing<T>*)&thing, &volatile_func5<T>);
     Verifier<T>::verify5((const volatile Thing<T>*)&thing, &const_volatile_func5<T>);
     Verifier<T>::verify5(callback(static_func5<T>));
-    Verifier<T>::verify5(callback(&thing, &Thing<T>::member_func5));
-    Verifier<T>::verify5(callback((const Thing<T>*)&thing, &Thing<T>::const_member_func5));
-    Verifier<T>::verify5(callback((volatile Thing<T>*)&thing, &Thing<T>::volatile_member_func5));
-    Verifier<T>::verify5(callback((const volatile Thing<T>*)&thing, &Thing<T>::const_volatile_member_func5));
-    Verifier<T>::verify5(callback(&thing, &bound_func5<T>));
-    Verifier<T>::verify5(callback((const Thing<T>*)&thing, &const_func5<T>));
-    Verifier<T>::verify5(callback((volatile Thing<T>*)&thing, &volatile_func5<T>));
-    Verifier<T>::verify5(callback((const volatile Thing<T>*)&thing, &const_volatile_func5<T>));
 
-    Callback<T(T, T, T, T, T)> callback(static_func5);
-    Verifier<T>::verify5(callback);
-    callback.attach(&thing, &bound_func5<T>);
-    Verifier<T>::verify5(&callback, &Callback<T(T, T, T, T, T)>::call);
-    Verifier<T>::verify5((void*)&callback, &Callback<T(T, T, T, T, T)>::thunk);
+    Callback<T(T, T, T, T, T)> cb(static_func5);
+    Verifier<T>::verify5(cb);
+    cb = static_func5;
+    Verifier<T>::verify5(cb);
+    cb.attach(&thing, &bound_func5<T>);
+    Verifier<T>::verify5(&cb, &Callback<T(T, T, T, T, T)>::call);
+    Verifier<T>::verify5((void*)&cb, &Callback<T(T, T, T, T, T)>::thunk);
 }
 
 template <typename T>

hal/api/FunctionPointer.h

@@ -43,6 +43,18 @@ public:
     R (*get_function())(A1) {
         return *reinterpret_cast<R (**)(A1)>(this);
     }
+
+    R call(A1 a1) const {
+        if (!Callback<R(A1)>::operator bool()) {
+            return (R)0;
+        }
+
+        return Callback<R(A1)>::call(a1);
+    }
+
+    R operator()(A1 a1) const {
+        return Callback<R(A1)>::call(a1);
+    }
 };
 
 template <typename R>
@@ -62,6 +74,18 @@ public:
     R (*get_function())() {
         return *reinterpret_cast<R (**)()>(this);
     }
+
+    R call() const {
+        if (!Callback<R()>::operator bool()) {
+            return (R)0;
+        }
+
+        return Callback<R()>::call();
+    }
+
+    R operator()() const {
+        return Callback<R()>::call();
+    }
 };
 
 typedef FunctionPointerArg1<void, void> FunctionPointer;

hal/common/CAN.cpp

@@ -21,8 +21,15 @@
 
 namespace mbed {
 
+static void donothing() {}
+
 CAN::CAN(PinName rd, PinName td) : _can(), _irq() {
     // No lock needed in constructor
+
+    for (int i = 0; i < sizeof _irq / sizeof _irq[0]; i++) {
+        _irq[i].attach(donothing);
+    }
+
     can_init(&_can, rd, td);
     can_irq_init(&_can, (&CAN::_irq_handler), (uint32_t)this);
 }
@@ -100,6 +107,7 @@ void CAN::attach(Callback<void()> func, IrqType type) {
         _irq[(CanIrqType)type].attach(func);
         can_irq_set(&_can, (CanIrqType)type, 1);
     } else {
+        _irq[(CanIrqType)type].attach(donothing);
         can_irq_set(&_can, (CanIrqType)type, 0);
     }
     unlock();

hal/common/InterruptIn.cpp

@@ -19,11 +19,17 @@
 
 namespace mbed {
 
+static void donothing() {}
+
 InterruptIn::InterruptIn(PinName pin) : gpio(),
                                         gpio_irq(),
                                         _rise(),
                                         _fall() {
     // No lock needed in the constructor
+
+    _rise.attach(donothing);
+    _fall.attach(donothing);
+
     gpio_irq_init(&gpio_irq, pin, (&InterruptIn::_irq_handler), (uint32_t)this);
     gpio_init_in(&gpio, pin);
 }
@@ -50,7 +56,7 @@ void InterruptIn::rise(Callback<void()> func) {
         _rise.attach(func);
         gpio_irq_set(&gpio_irq, IRQ_RISE, 1);
     } else {
-        _rise.attach(NULL);
+        _rise.attach(donothing);
         gpio_irq_set(&gpio_irq, IRQ_RISE, 0);
     }
     core_util_critical_section_exit();
@@ -62,7 +68,7 @@ void InterruptIn::fall(Callback<void()> func) {
         _fall.attach(func);
         gpio_irq_set(&gpio_irq, IRQ_FALL, 1);
     } else {
-        _fall.attach(NULL);
+        _fall.attach(donothing);
         gpio_irq_set(&gpio_irq, IRQ_FALL, 0);
     }
     core_util_critical_section_exit();

hal/common/SerialBase.cpp

@@ -21,6 +21,8 @@
 
 namespace mbed {
 
+static void donothing() {};
+
 SerialBase::SerialBase(PinName tx, PinName rx) :
 #if DEVICE_SERIAL_ASYNCH
                                                  _thunk_irq(this), _tx_usage(DMA_USAGE_NEVER),
@@ -29,6 +31,10 @@ SerialBase::SerialBase(PinName tx, PinName rx) :
                                                 _serial(), _baud(9600) {
     // No lock needed in the constructor
 
+    for (int i = 0; i < sizeof _irq / sizeof _irq[0]; i++) {
+        _irq[i].attach(donothing);
+    }
+
     serial_init(&_serial, tx, rx);
     serial_irq_handler(&_serial, SerialBase::_irq_handler, (uint32_t)this);
 }
@@ -69,6 +75,7 @@ void SerialBase::attach(Callback<void()> func, IrqType type) {
         _irq[type].attach(func);
         serial_irq_set(&_serial, (SerialIrq)type, 1);
     } else {
+        _irq[type].attach(donothing);
         serial_irq_set(&_serial, (SerialIrq)type, 0);
     }
     core_util_critical_section_exit();