From bf498de1277000d2aa821c9daf2d5c80e6d54105 Mon Sep 17 00:00:00 2001
From: Christopher Haster <chaster@utexas.edu>
Date: Fri, 13 May 2016 14:55:48 -0500
Subject: [PATCH] Add backward compatiblity for FunctionPointer class using
 Callback

effectively:
typedef Callback<R(A)> FunctionPointerArg1<R,A>
typedef Callback<R()> FunctionPointerArg1<R,void>
typedef Callback<R()> FunctionPointer
typedef Callback<R()> event_callback_t
---
 hal/TESTS/api/callback/main.cpp |  19 ++++
 hal/api/FunctionPointer.h       | 174 ++++----------------------------
 hal/api/mbed.h                  |   1 +
 3 files changed, 38 insertions(+), 156 deletions(-)

diff --git a/hal/TESTS/api/callback/main.cpp b/hal/TESTS/api/callback/main.cpp
index 057b5ac367..27fab43173 100644
--- a/hal/TESTS/api/callback/main.cpp
+++ b/hal/TESTS/api/callback/main.cpp
@@ -211,6 +211,22 @@ void test_dispatch0() {
     Verifier<T>::verify0((void*)&callback, &Callback<T()>::thunk);
 }
 
+template <typename T>
+void test_fparg1() {
+    Thing<T> thing;
+    FunctionPointerArg1<T,T> fp(static_func1<T>);
+    Verifier<T>::verify1(fp);
+    Verifier<T>::verify1(fp.get_function());
+}
+
+template <typename T>
+void test_fparg0() {
+    Thing<T> thing;
+    FunctionPointerArg1<T,void> fp(static_func0<T>);
+    Verifier<T>::verify0(fp);
+    Verifier<T>::verify0(fp.get_function());
+}
+
 
 // Test setup
 status_t test_setup(const size_t number_of_cases) {
@@ -239,6 +255,9 @@ Case cases[] = {
     Case("Testing callbacks with 2 uint64s", test_dispatch2<uint64_t>),
     Case("Testing callbacks with 1 uint64s", test_dispatch1<uint64_t>),
     Case("Testing callbacks with 0 uint64s", test_dispatch0<uint64_t>),
+
+    Case("Testing FunctionPointerArg1 compatibility", test_fparg1<int>),
+    Case("Testing FunctionPointer compatibility", test_fparg0<int>),
 };
 
 Specification specification(test_setup, cases);
diff --git a/hal/api/FunctionPointer.h b/hal/api/FunctionPointer.h
index 2d49ba035e..b2ef2b971c 100644
--- a/hal/api/FunctionPointer.h
+++ b/hal/api/FunctionPointer.h
@@ -16,187 +16,49 @@
 #ifndef MBED_FUNCTIONPOINTER_H
 #define MBED_FUNCTIONPOINTER_H
 
+#include "Callback.h"
 #include <string.h>
 #include <stdint.h>
 
 namespace mbed {
 
-/* If we had variaditic templates, this wouldn't be a problem, but until C++11 is enabled, we are stuck with multiple classes... */
 
-/** A class for storing and calling a pointer to a static or member function
- */
+// Declarations for backwards compatibility
+// To be foward compatible, code should adopt the Callback class
 template <typename R, typename A1>
-class FunctionPointerArg1{
+class FunctionPointerArg1 : public Callback<R(A1)> {
 public:
-    /** Create a FunctionPointer, attaching a static function
-     *
-     *  @param function The static function to attach (default is none)
-     */
-    FunctionPointerArg1(R (*function)(A1) = 0) {
-        attach(function);
-    }
+    FunctionPointerArg1(R (*function)(A1) = 0)
+        : Callback<R(A1)>(function) {}
 
-    /** Create a FunctionPointer, attaching a member function
-     *
-     *  @param object The object pointer to invoke the member function on (i.e. the this pointer)
-     *  @param function The address of the member function to attach
-     */
     template<typename T>
-    FunctionPointerArg1(T *object, R (T::*member)(A1)) {
-        attach(object, member);
-    }
+    FunctionPointerArg1(T *object, R (T::*member)(A1))
+        : Callback<R(A1)>(object, member) {}
 
-    /** Attach a static function
-     *
-     *  @param function The static function to attach (default is none)
-     */
-    void attach(R (*function)(A1)) {
-        _p.function = function;
-        _membercaller = 0;
+    R (*get_function())(A1) {
+        return *reinterpret_cast<R (**)(A1)>(this);
     }
-
-    /** Attach a member function
-     *
-     *  @param object The object pointer to invoke the member function on (i.e. the this pointer)
-     *  @param function The address of the member function to attach
-     */
-    template<typename T>
-    void attach(T *object, R (T::*member)(A1)) {
-        _p.object = static_cast<void*>(object);
-        *reinterpret_cast<R (T::**)(A1)>(_member) = member;
-        _membercaller = &FunctionPointerArg1::membercaller<T>;
-    }
-
-    /** Call the attached static or member function
-     */
-    R call(A1 a) {
-        if (_membercaller == 0 && _p.function) {
-           return _p.function(a);
-        } else if (_membercaller && _p.object) {
-           return _membercaller(_p.object, _member, a);
-        }
-        return (R)0;
-    }
-
-    /** Get registered static function
-     */
-    R(*get_function(A1))() {
-        return _membercaller ? (R(*)(A1))0 : (R(*)(A1))_p.function;
-    }
-
-#ifdef MBED_OPERATORS
-    R operator ()(A1 a) {
-        return call(a);
-    }
-    operator bool(void) const {
-        return (_membercaller != NULL ? _p.object : (void*)_p.function) != NULL;
-    }
-#endif
-private:
-    template<typename T>
-    static R membercaller(void *object, uintptr_t *member, A1 a) {
-        T* o = static_cast<T*>(object);
-        R (T::**m)(A1) = reinterpret_cast<R (T::**)(A1)>(member);
-        return (o->**m)(a);
-    }
-
-    union {
-        R (*function)(A1); // static function pointer
-        void *object;      // object this pointer
-    } _p;
-    uintptr_t _member[4]; // aligned raw member function pointer storage - converted back by registered _membercaller
-    R (*_membercaller)(void*, uintptr_t*, A1); // registered membercaller function to convert back and call _m.member on _object
 };
 
-/** A class for storing and calling a pointer to a static or member function (R ()(void))
- */
 template <typename R>
-class FunctionPointerArg1<R, void>{
+class FunctionPointerArg1<R, void> : public Callback<R()> {
 public:
-    /** Create a FunctionPointer, attaching a static function
-     *
-     *  @param function The static function to attach (default is none)
-     */
-    FunctionPointerArg1(R (*function)(void) = 0) {
-        attach(function);
-    }
+    FunctionPointerArg1(R (*function)() = 0)
+        : Callback<R()>(function) {}
 
-    /** Create a FunctionPointer, attaching a member function
-     *
-     *  @param object The object pointer to invoke the member function on (i.e. the this pointer)
-     *  @param function The address of the void member function to attach
-     */
     template<typename T>
-    FunctionPointerArg1(T *object, R (T::*member)(void)) {
-        attach(object, member);
-    }
+    FunctionPointerArg1(T *object, R (T::*member)())
+        : Callback<R()>(object, member) {}
 
-    /** Attach a static function
-     *
-     *  @param function The void static function to attach (default is none)
-     */
-    void attach(R (*function)(void)) {
-        _p.function = function;
-        _membercaller = 0;
+    R (*get_function())() {
+        return *reinterpret_cast<R (**)()>(this);
     }
-
-    /** Attach a member function
-     *
-     *  @param object The object pointer to invoke the member function on (i.e. the this pointer)
-     *  @param function The address of the void member function to attach
-     */
-    template<typename T>
-    void attach(T *object, R (T::*member)(void)) {
-        _p.object = static_cast<void*>(object);
-        *reinterpret_cast<R (T::**)(void)>(_member) = member;
-        _membercaller = &FunctionPointerArg1::membercaller<T>;
-    }
-
-    /** Call the attached static or member function
-     */
-    R call(){
-        if (_membercaller == 0 && _p.function) {
-            return _p.function();
-        } else if (_membercaller && _p.object) {
-            return _membercaller(_p.object, _member);
-        }
-        return (R)0;
-    }
-
-    /** Get registered static function
-     */
-    R(*get_function())() {
-        return _membercaller ? (R(*)())0 : (R(*)())_p.function;
-    }
-
-#ifdef MBED_OPERATORS
-    R operator ()(void) {
-        return call();
-    }
-    operator bool(void) const {
-        return (_membercaller != NULL ? _p.object : (void*)_p.function) != NULL;
-    }
-#endif
-
-private:
-    template<typename T>
-    static R membercaller(void *object, uintptr_t *member) {
-        T* o = static_cast<T*>(object);
-        R (T::**m)(void) = reinterpret_cast<R (T::**)(void)>(member);
-        return (o->**m)();
-    }
-
-    union {
-        R (*function)(void); // static function pointer
-        void *object;        // object this pointer
-    } _p;
-    uintptr_t _member[4]; // aligned raw member function pointer storage - converted back by registered _membercaller
-    R (*_membercaller)(void*, uintptr_t*); // registered membercaller function to convert back and call _m.member on _object
 };
 
 typedef FunctionPointerArg1<void, void> FunctionPointer;
 typedef FunctionPointerArg1<void, int> event_callback_t;
 
+
 } // namespace mbed
 
 #endif
diff --git a/hal/api/mbed.h b/hal/api/mbed.h
index 8d615d4c6f..e1a6a12e01 100644
--- a/hal/api/mbed.h
+++ b/hal/api/mbed.h
@@ -66,6 +66,7 @@
 
 // mbed Non-hardware components
 #include "Callback.h"
+#include "FunctionPointer.h"
 
 using namespace mbed;
 using namespace std;