New MQTT-SN high level client API

MQTTSNClient/src/FP.h

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+/*******************************************************************************
+ * Copyright (c) 2013, 2014 
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * and Eclipse Distribution License v1.0 which accompany this distribution.
+ *
+ * The Eclipse Public License is available at
+ *    http://www.eclipse.org/legal/epl-v10.html
+ * and the Eclipse Distribution License is available at
+ *   http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * Contributors:
+ *    Sam Grove - initial API and implementation and/or initial documentation
+ *    Ian Craggs - added attached and detached member functions
+ *    Sam Grove - removed need for FP.cpp
+ *******************************************************************************/
+
+#ifndef FP_H
+#define FP_H
+
+/** Example using the FP Class with global functions
+ * @code
+ *  #include "mbed.h"
+ *  #include "FP.h"
+ *
+ *  FP<void,bool>fp;
+ *  DigitalOut myled(LED1);
+ *
+ *  void handler(bool value)
+ *  {
+ *      myled = value;
+ *      return;
+ *  }
+ *
+ *  int main()
+ *  {
+ *      fp.attach(&handler);
+ *
+ *      while(1)
+ *      {
+ *          fp(1);
+ *          wait(0.2);
+ *          fp(0);
+ *          wait(0.2);
+ *      }
+ *  }
+ * @endcode
+ */
+
+/** Example using the FP Class with different class member functions
+ * @code
+ *  #include "mbed.h"
+ *  #include "FP.h"
+ *
+ *  FP<void,bool>fp;
+ *  DigitalOut myled(LED4);
+ *
+ *  class Wrapper
+ *  {
+ *  public:
+ *      Wrapper(){}
+ *
+ *      void handler(bool value)
+ *      {
+ *          myled = value;
+ *          return;
+ *      }
+ *  };
+ *
+ *  int main()
+ *  {
+ *      Wrapper wrapped;
+ *      fp.attach(&wrapped, &Wrapper::handler);
+ *
+ *      while(1)
+ *      {
+ *          fp(1);
+ *          wait(0.2);
+ *          fp(0);
+ *          wait(0.2);
+ *      }
+ *  }
+ * @endcode
+ */
+
+/** Example using the FP Class with member FP and member function
+* @code
+*  #include "mbed.h"
+*  #include "FP.h"
+*
+*  DigitalOut myled(LED2);
+*
+*  class Wrapper
+*  {
+*  public:
+*      Wrapper()
+*      {
+*          fp.attach(this, &Wrapper::handler);
+*      }
+*
+*      void handler(bool value)
+*      {
+*          myled = value;
+*          return;
+*      }
+*
+*      FP<void,bool>fp;
+*  };
+*
+*  int main()
+*  {
+*      Wrapper wrapped;
+*
+*      while(1)
+*      {
+*          wrapped.fp(1);
+*          wait(0.2);
+*          wrapped.fp(0);
+*          wait(0.2);
+*      }
+*  }
+* @endcode
+*/
+
+/**
+ *  @class FP
+ *  @brief API for managing Function Pointers
+ */
+template<class retT, class argT>
+class FP
+{
+public:
+    /** Create the FP object - only one callback can be attached to the object, that is
+     *  a member function or a global function, not both at the same time
+     */
+    FP()
+    {
+        obj_callback = 0;
+        c_callback = 0;
+    }
+
+    /** Add a callback function to the object
+     *  @param item - Address of the initialized object
+     *  @param member - Address of the member function (dont forget the scope that the function is defined in)
+     */
+    template<class T>
+    void attach(T *item, retT (T::*method)(argT))
+    {
+        obj_callback = (FPtrDummy *)(item);
+        method_callback = (retT (FPtrDummy::*)(argT))(method);
+        return;
+    }
+
+    /** Add a callback function to the object
+     *  @param function - The address of a globally defined function
+     */
+    void attach(retT (*function)(argT))
+    {
+        c_callback = function;
+    }
+
+    /** Invoke the function attached to the class
+     *  @param arg - An argument that is passed into the function handler that is called
+     *  @return The return from the function hanlder called by this class
+     */
+    retT operator()(argT arg) const
+    {
+        if( 0 != c_callback ) {
+            return obj_callback ? (obj_callback->*method_callback)(arg) : (*c_callback)(arg);
+        }
+        return (retT)0;
+    }
+
+    /** Determine if an callback is currently hooked
+     *  @return 1 if a method is hooked, 0 otherwise
+     */
+    bool attached()
+    {
+        return obj_callback || c_callback;
+    }
+
+    /** Release a function from the callback hook
+     */
+    void detach()
+    {
+        obj_callback = 0;
+        c_callback = 0;
+    }
+
+private:
+
+    // empty type used for casting
+    class FPtrDummy;
+
+    FPtrDummy *obj_callback;
+
+    /**
+     *  @union Funciton
+     *  @brief Member or global callback function
+     */
+    union {
+        retT (*c_callback)(argT);                   /*!< Footprint for a global function */
+        retT (FPtrDummy::*method_callback)(argT);   /*!< Footprint for a member function */
+    };
+};
+
+#endif