/////////////////////////////////////////////////////////////////
//  PTS.cpp - Issue #4 : partial template specialization       //
//                                                             //
//  Jim Fawcett, CSE687 - Object Oriented Design, Spring 2005  //
/////////////////////////////////////////////////////////////////
//
//  Partial Template Specialization:
//  Allows you to specialize a subset of a class's template
//  parameters.
//
//  Below we give an example of a smart pointer designed
//  to handle arrays of some fixed size, determined by the
//  integer template parameter.
//
//  For non-arrays we specialize the template for size=1,
//  leaving the type parameter T unspecified.

#include <string>
#include <iostream>

template <typename T, int size>
class smartPtr
{
public:
  smartPtr(T* pTr = 0)
  {
    pTr_ = new T[size];
    if(pTr)
      for(int i=0; i<size; ++i)
        pTr_[i] = *pTr;
  }
  ~smartPtr() { delete [] pTr_; }
  T& operator*() { return *pTr_; }
  T* operator->() { return pTr_; }
  T* operator+(size_t i) { return pTr_ + i; }
  T operator[] (int n) const { return pTr_[n]; }
  T& operator[](int n) { return pTr_[n]; }
  // other members
private:
  T* pTr_;
};

template <typename T>
class smartPtr<T,1>
{
public:
  smartPtr(T* pTr) : pTr_(new T(*pTr)) {}
  ~smartPtr() { delete pTr_; }
  T& operator*() { return *pTr_; }
  T* operator->() { return pTr_; }
  // note that operator[] and operator+ are not supplied
  // other members
private:
  T* pTr_;
};
//
void main()
{
  std::cout << "\n  Demonstrating Partial Template Specialization";
  std::cout << "\n ===============================================\n";

  std::cout << "\n  Creating smart pointer to string array";
  std::cout << "\n ----------------------------------------";
  smartPtr<std::string,3> spArray;
  std::cout << "\n  defining string array elements through smart pointer indexing";
  spArray[0] = "first string";
  spArray[1] = "second string";
  spArray[2] = "third string";
  std::cout << "\n  accessing string array contents using smart pointer dereferencing:";
  for(int i=0; i<3; ++i)
    std::cout << "\n    " << *(spArray + i);
  std::cout << "\n  using smart pointer selection to access array element:";
  std::cout << "\n    first element of target string array has " << spArray->size() << " characters";
  std::cout << "\n  creating another smart pointer to the same array";
  smartPtr<std::string,3> spArray2(&spArray[0]);
  std::cout << "\n  smart pointer indexing through array";
  for(int i=0; i<3; ++i)
    std::cout << "\n    " << spArray2[i];
  std::cout << "\n";

  std::cout << "\n  Creating no array specialization of smart pointer referring to string";
  std::cout << "\n -----------------------------------------------------------------------";
  std::string s2 = "another string";
  smartPtr<std::string,1> spNoArray(&s2);
  std::cout << "\n  using dereferencing to access string:";
  std::cout << "\n    " << *spNoArray;
  std::cout << "\n  selecting target element:";
  std::cout << "\n    there are " << spNoArray->size() << " characters in this string";
  std::cout << "\n\n";
}