///////////////////////////////////////////////////////////////
//  factoryb.cpp - defines interface and factory             //
//  Exam2:Q7                                                 //
//  Jim Fawcett, CSE687 - Object Oriented Design, Spring 05  //
///////////////////////////////////////////////////////////////

#include <string>
#include <iostream>

template <typename T, typename U>
class HeadAndTail : public T
{
public:
  HeadAndTail(const T& t) : T(t) {}
  virtual ~HeadAndTail() {}
  static U* Create(const T& t);
  virtual U head(unsigned int pos) = 0;
  virtual U tail(unsigned int pos) = 0;
};

template <typename T, typename U>
U* HeadAndTail<T,U>::Create(const T& t)
{
  return new U(t);
}

class stringPlus;

typedef HeadAndTail<std::string, stringPlus> HandT;

class stringPlus : public HandT
{
public:
  stringPlus(const std::string& s) : HandT(s) {}
  virtual stringPlus head(unsigned int pos)
  {
    std::string temp = substr(0,pos);
    return temp;
  }
  virtual stringPlus tail(unsigned int pos)
  {
    return substr(pos,size()-pos-1);
  }
};

void main()
{
  std::string msg = "Now is the hour for all good men to ... ";
  HandT* pHAT = HandT::Create(msg);
  std::cout << "\n  " << pHAT->head(msg.size()).c_str();
  std::cout << "\n  " << pHAT->head(7).c_str();
  std::cout << "\n  " << pHAT->tail(7).c_str();

  std::cout << "\n\n";
}