/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2005,2006 INRIA

 * All rights reserved.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 */

#ifndef CALLBACK_H

#define CALLBACK_H

#include "reference-list.h"

namespace ns3 {

/***

 * \internal

 * This code was originally written based on the techniques 

 * described in http://www.codeproject.com/cpp/TTLFunction.asp

 * It was subsequently rewritten to follow the architecture

 * outlined in "Modern C++ Design" by Andrei Alexandrescu in 

 * chapter 5, "Generalized Functors".

 *

 * This code uses:

 *   - default template parameters to saves users from having to

 *     specify empty parameters when the number of parameters

 *     is smaller than the maximum supported number

 *   - the pimpl idiom: the Callback class is passed around by 

 *     value and delegates the crux of the work to its pimpl

 *     pointer.

 *   - two pimpl implementations which derive from CallbackImpl

 *     FunctorCallbackImpl can be used with any functor-type

 *     while MemPtrCallbackImpl can be used with pointers to

 *     member functions.

 *   - a reference list implementation to implement the Callback's

 *     value semantics.

 *

 * This code most notably departs from the alexandrescu 

 * implementation in that it does not use type lists to specify

 * and pass around the types of the callback arguments.

 * Of course, it also does not use copy-destruction semantics

 * and relies on a reference list rather than autoPtr to hold

 * the pointer.

 */

class empty {};

class CallbackImplBase {

public:

  virtual ~CallbackImplBase () {}

  virtual bool IsEqual (CallbackImplBase const *other) const = 0;

};

// declare the CallbackImpl class

template <typename R, typename T1, typename T2, typename T3, typename T4, typename T5>

class CallbackImpl;

// define CallbackImpl for 0 params

template <typename R>

class CallbackImpl<R,empty,empty,empty,empty,empty> : public CallbackImplBase {

public:

  virtual ~CallbackImpl () {}

  virtual R operator() (void) = 0;

};

// define CallbackImpl for 1 params

template <typename R, typename T1>

class CallbackImpl<R,T1,empty,empty,empty,empty> : public CallbackImplBase {

public:

  virtual ~CallbackImpl () {}

  virtual R operator() (T1) = 0;

};

// define CallbackImpl for 2 params

template <typename R, typename T1, typename T2>

class CallbackImpl<R,T1,T2,empty,empty,empty> : public CallbackImplBase {

public:

  virtual ~CallbackImpl () {}

  virtual R operator() (T1, T2) = 0;

};

// define CallbackImpl for 3 params

template <typename R, typename T1, typename T2, typename T3>

class CallbackImpl<R,T1,T2,T3,empty,empty> : public CallbackImplBase {

public:

  virtual ~CallbackImpl () {}

  virtual R operator() (T1, T2, T3) = 0;

};

// define CallbackImpl for 4 params

template <typename R, typename T1, typename T2, typename T3, typename T4>

class CallbackImpl<R,T1,T2,T3,T4,empty> : public CallbackImplBase {

public:

  virtual ~CallbackImpl () {}

  virtual R operator() (T1, T2, T3, T4) = 0;

};

// define CallbackImpl for 5 params

template <typename R, typename T1, typename T2, typename T3, typename T4, typename T5>

class CallbackImpl : public CallbackImplBase {

public:

  virtual ~CallbackImpl () {}

  virtual R operator() (T1, T2, T3, T4, T5) = 0;

};

// an impl for Functors:

template <typename T, typename R, typename T1, typename T2, typename T3, typename T4,typename T5>

class FunctorCallbackImpl : public CallbackImpl<R,T1,T2,T3,T4,T5> {

public:

  FunctorCallbackImpl (T const &functor)

      : m_functor (functor) {}

  virtual ~FunctorCallbackImpl () {}

  R operator() (void) {

      return m_functor ();

  }

  R operator() (T1 a1) {

      return m_functor (a1);

  }

  R operator() (T1 a1,T2 a2) {

      return m_functor (a1,a2);

  }

  R operator() (T1 a1,T2 a2,T3 a3) {

      return m_functor (a1,a2,a3);

  }

  R operator() (T1 a1,T2 a2,T3 a3,T4 a4) {

      return m_functor (a1,a2,a3,a4);

  }

  R operator() (T1 a1,T2 a2,T3 a3,T4 a4,T5 a5) {

      return m_functor (a1,a2,a3,a4,a5);

  }

  virtual bool IsEqual (CallbackImplBase const *other) const {

    FunctorCallbackImpl<T,R,T1,T2,T3,T4,T5> const *otherDerived = 

      dynamic_cast<FunctorCallbackImpl<T,R,T1,T2,T3,T4,T5> const *> (other);

    if (otherDerived == 0)

      {

        return false;

      }

    else if (otherDerived->m_functor != m_functor)

      {

        return false;

      }

    return true;

  }

private:

  T m_functor;

};

// an impl for pointer to member functions

template <typename OBJ_PTR, typename MEM_PTR, typename R, typename T1, typename T2, typename T3, typename T4, typename T5>

class MemPtrCallbackImpl : public CallbackImpl<R,T1,T2,T3,T4,T5> {

public:

  MemPtrCallbackImpl (OBJ_PTR const&objPtr, MEM_PTR mem_ptr)

      : m_objPtr (objPtr), m_memPtr (mem_ptr) {}

  virtual ~MemPtrCallbackImpl () {}

  R operator() (void) {

      return ((*m_objPtr).*m_memPtr) ();

  }

  R operator() (T1 a1) {

      return ((*m_objPtr).*m_memPtr) (a1);

  }

  R operator() (T1 a1,T2 a2) {

      return ((*m_objPtr).*m_memPtr) (a1,a2);

  }

  R operator() (T1 a1,T2 a2,T3 a3) {

      return ((*m_objPtr).*m_memPtr) (a1,a2,a3);

  }

  R operator() (T1 a1,T2 a2,T3 a3,T4 a4) {

      return ((*m_objPtr).*m_memPtr) (a1,a2,a3,a4);

  }

  R operator() (T1 a1,T2 a2,T3 a3,T4 a4,T5 a5) {

      return ((*m_objPtr).*m_memPtr) (a1,a2,a3,a4,a5);

  }

  virtual bool IsEqual (CallbackImplBase const *other) const {

    MemPtrCallbackImpl<OBJ_PTR,MEM_PTR,R,T1,T2,T3,T4,T5> const *otherDerived = 

      dynamic_cast<MemPtrCallbackImpl<OBJ_PTR,MEM_PTR,R,T1,T2,T3,T4,T5> const *> (other);

    if (otherDerived == 0)

      {

        return false;

      }

    else if (otherDerived->m_objPtr != m_objPtr ||

             otherDerived->m_memPtr != m_memPtr)

      {

        return false;

      }

    return true;

  }

private:

  OBJ_PTR const m_objPtr;

  MEM_PTR m_memPtr;

};

class CallbackBase {

public:

  virtual ~CallbackBase () {}

  virtual CallbackImplBase *PeekImpl (void) const = 0;

};

/**

 * \brief Callback template class

 *

 * This class template implements the Functor Design Pattern.

 * It is used to declare the type of a Callback:

 *  - the first non-optional template argument represents

 *    the return type of the callback.

 *  - the second optional template argument represents

 *    the type of the first argument to the callback.

 *  - the third optional template argument represents

 *    the type of the second argument to the callback.

 *  - the fourth optional template argument represents

 *    the type of the third argument to the callback.

 *  - the fifth optional template argument represents

 *    the type of the fourth argument to the callback.

 *  - the sixth optional template argument represents

 *    the type of the fifth argument to the callback.

 *

 * Callback instances are built with the \ref MakeCallback

 * template functions. Callback instances have POD semantics:

 * the memory they allocate is managed automatically, without

 * user intervention which allows you to pass around Callback

 * instances by value.

 *

 * Sample code which shows how to use this class template 

 * as well as the function templates \ref MakeCallback :

 * \include samples/main-callback.cc

 */

template<typename R, 

   typename T1 = empty, typename T2 = empty, 

   typename T3 = empty, typename T4 = empty,

   typename T5 = empty>

class Callback : public CallbackBase {

public:

  // There are two dummy args below to ensure that this constructor is

  // always properly disambiguited by the c++ compiler

  template <typename FUNCTOR>

  Callback (FUNCTOR const &functor, bool, bool) 

      : m_impl (new FunctorCallbackImpl<FUNCTOR,R,T1,T2,T3,T4,T5> (functor))

  {}

  template <typename OBJ_PTR, typename MEM_PTR>

  Callback (OBJ_PTR const &objPtr, MEM_PTR mem_ptr)

      : m_impl (new MemPtrCallbackImpl<OBJ_PTR,MEM_PTR,R,T1,T2,T3,T4,T5> (objPtr, mem_ptr))

  {}

  Callback (ReferenceList<CallbackImpl<R,T1,T2,T3,T4,T5> *> const &impl)

      : m_impl (impl)

  {}

  bool IsNull (void) {

      return (m_impl.Get () == 0)?true:false;

  }

  Callback () : m_impl () {}

  R operator() (void) const {

      return (*(m_impl.Get ())) ();

  }

  R operator() (T1 a1) const {

      return (*(m_impl.Get ())) (a1);

  }

  R operator() (T1 a1, T2 a2) const {

      return (*(m_impl).Get ()) (a1,a2);

  }

  R operator() (T1 a1, T2 a2, T3 a3) const {

      return (*(m_impl).Get ()) (a1,a2,a3);

  }

  R operator() (T1 a1, T2 a2, T3 a3, T4 a4) const {

      return (*(m_impl).Get ()) (a1,a2,a3,a4);

  }

  R operator() (T1 a1, T2 a2, T3 a3, T4 a4,T5 a5) const {

      return (*(m_impl).Get ()) (a1,a2,a3,a4,a5);

  }

  bool IsEqual (CallbackBase const &other) {

    return PeekImpl ()->IsEqual (other.PeekImpl ());

  }

  bool CheckType (CallbackBase const& other) {

    CallbackImplBase *otherBase = other.PeekImpl ();

    if (dynamic_cast<CallbackImpl<R,T1,T2,T3,T4,T5> *> (otherBase) != 0)

      {

        return true;

      }

    else

      {

        return false;

      }

  }

private:

  virtual CallbackImplBase *PeekImpl (void) const {

    return m_impl.Get ();

  }

  ReferenceList<CallbackImpl<R,T1,T2,T3,T4,T5>*> m_impl;

};

/**

 * \defgroup MakeCallback MakeCallback

 *

 */

/**

 * \ingroup MakeCallback

 * \param mem_ptr class method member pointer

 * \param objPtr class instance

 * \return a wrapper Callback

 * Build Callbacks for class method members which takes no arguments

 * and potentially return a value.

 */

template <typename OBJ, typename R>

Callback<R> MakeCallback (R (OBJ::*mem_ptr) (), OBJ *const objPtr) {

  return Callback<R> (objPtr, mem_ptr);

}

/**

 * \ingroup MakeCallback

 * \param mem_ptr class method member pointer

 * \param objPtr class instance

 * \return a wrapper Callback

 * Build Callbacks for class method members which takes one argument

 * and potentially return a value.

 */

template <typename OBJ, typename R, typename T1>

Callback<R,T1> MakeCallback (R (OBJ::*mem_ptr) (T1), OBJ *const objPtr) {

  return Callback<R,T1> (objPtr, mem_ptr);

}

/**

 * \ingroup MakeCallback

 * \param mem_ptr class method member pointer

 * \param objPtr class instance

 * \return a wrapper Callback

 * Build Callbacks for class method members which takes two arguments

 * and potentially return a value.

 */

template <typename OBJ, typename R, typename T1, typename T2>

Callback<R,T1,T2> MakeCallback (R (OBJ::*mem_ptr) (T1,T2), OBJ *const objPtr) {

  return Callback<R,T1,T2> (objPtr, mem_ptr);

}

/**

 * \ingroup MakeCallback

 * \param mem_ptr class method member pointer

 * \param objPtr class instance

 * \return a wrapper Callback

 * Build Callbacks for class method members which takes three arguments

 * and potentially return a value.

 */

template <typename OBJ, typename R, typename T1,typename T2, typename T3>

Callback<R,T1,T2,T3> MakeCallback (R (OBJ::*mem_ptr) (T1,T2,T3), OBJ *const objPtr) {

  return Callback<R,T1,T2,T3> (objPtr, mem_ptr);

}

/**

 * \ingroup MakeCallback

 * \param mem_ptr class method member pointer

 * \param objPtr class instance

 * \return a wrapper Callback

 * Build Callbacks for class method members which takes four arguments

 * and potentially return a value.

 */

template <typename OBJ, typename R, typename T1, typename T2, typename T3, typename T4>

Callback<R,T1,T2,T3,T4> MakeCallback (R (OBJ::*mem_ptr) (T1,T2,T3,T4), OBJ *const objPtr) {

  return Callback<R,T1,T2,T3,T4> (objPtr, mem_ptr);

}

/**

 * \ingroup MakeCallback

 * \param mem_ptr class method member pointer

 * \param objPtr class instance

 * \return a wrapper Callback

 * Build Callbacks for class method members which takes five arguments

 * and potentially return a value.

 */

template <typename OBJ, typename R, typename T1, typename T2, typename T3, typename T4,typename T5>

Callback<R,T1,T2,T3,T4,T5> MakeCallback (R (OBJ::*mem_ptr) (T1,T2,T3,T4,T5), OBJ *const objPtr) {

  return Callback<R,T1,T2,T3,T4,T5> (objPtr, mem_ptr);

}

/**

 * \ingroup MakeCallback

 * \param fnPtr function pointer

 * \return a wrapper Callback

 * Build Callbacks for functions which takes no arguments

 * and potentially return a value.

 */

template <typename R>

Callback<R> MakeCallback (R (*fnPtr) ()) {

  return Callback<R> (fnPtr, true, true);

}

/**

 * \ingroup MakeCallback

 * \param fnPtr function pointer

 * \return a wrapper Callback

 * Build Callbacks for functions which takes one argument

 * and potentially return a value.

 */

template <typename R, typename T1>

Callback<R,T1> MakeCallback (R (*fnPtr) (T1)) {

  return Callback<R,T1> (fnPtr, true, true);

}

/**

 * \ingroup MakeCallback

 * \param fnPtr function pointer

 * \return a wrapper Callback

 * Build Callbacks for functions which takes two arguments

 * and potentially return a value.

 */

template <typename R, typename T1, typename T2>

Callback<R,T1,T2> MakeCallback (R (*fnPtr) (T1,T2)) {

  return Callback<R,T1,T2> (fnPtr, true, true);

}

/**

 * \ingroup MakeCallback

 * \param fnPtr function pointer

 * \return a wrapper Callback

 * Build Callbacks for functions which takes three arguments

 * and potentially return a value.

 */

template <typename R, typename T1, typename T2,typename T3>

Callback<R,T1,T2,T3> MakeCallback (R (*fnPtr) (T1,T2,T3)) {

  return Callback<R,T1,T2,T3> (fnPtr, true, true);

}

/**

 * \ingroup MakeCallback

 * \param fnPtr function pointer

 * \return a wrapper Callback

 * Build Callbacks for functions which takes four arguments

 * and potentially return a value.

 */

template <typename R, typename T1, typename T2,typename T3,typename T4>

Callback<R,T1,T2,T3,T4> MakeCallback (R (*fnPtr) (T1,T2,T3,T4)) {

  return Callback<R,T1,T2,T3,T4> (fnPtr, true, true);

}

/**

 * \ingroup MakeCallback

 * \param fnPtr function pointer

 * \return a wrapper Callback

 * Build Callbacks for functions which takes five arguments

 * and potentially return a value.

 */

template <typename R, typename T1, typename T2,typename T3,typename T4,typename T5>

Callback<R,T1,T2,T3,T4,T5> MakeCallback (R (*fnPtr) (T1,T2,T3,T4,T5)) {

  return Callback<R,T1,T2,T3,T4,T5> (fnPtr, true, true);

}

/**

 * \ingroup MakeCallback

 * \return a wrapper Callback

 * Build a null callback which takes no arguments

 * and potentially return a value.

 */

template <typename R>

Callback<R> MakeNullCallback (void) {

  return Callback<R> ();

}

/**

 * \ingroup MakeCallback

 * \overload Callback<R> MakeNullCallback (void)

 * \return a wrapper Callback

 * Build a null callback which takes one argument

 * and potentially return a value.

 */

template <typename R, typename T1>

Callback<R,T1> MakeNullCallback (void) {

  return Callback<R,T1> ();

}

/**

 * \ingroup MakeCallback

 * \overload Callback<R> MakeNullCallback (void)

 * \return a wrapper Callback

 * Build a null callback which takes two arguments

 * and potentially return a value.