/////////////////////////////////////////////////////////////////
//  invoker.cpp - defines class to wrap function pointers      //
//  Exam3:Q5                                                   //
//  Jim Fawcett, CSE687 - Object Oriented Design, Spring 05    //
/////////////////////////////////////////////////////////////////

#include <string>
#include <iostream>

template <typename R, typename A>
class delegate
{
public:
  typedef R(*fPtr)(A);

  virtual ~delegate() {}

  void operator+=(fPtr fp)
  {
    fptr_ = fp;
  }

  virtual R invoke(A a)
  {
    return fptr_(a);
  }
private:
  fPtr fptr_;
};

int trunc(const double& d)
{
  return static_cast<int>(d);
}

struct Str { int i; double d; };

void SimulateMultipleArgs(const Str& s)
{
  std::cout << "\n  s.i = " << s.i;
  std::cout << "\n  s.d = " << s.d;
}

void main()
{
  delegate<int,const double&> del;
  del += trunc;
  std::cout << "\n  received " << del.invoke(3.5) << " from invoker\n\n";

  Str str = { 1, 3.1415927 };
  delegate<void,const Str&> sdel;
  sdel += SimulateMultipleArgs;
  sdel.invoke(str);
  std::cout << "\n\n";
}