/*
 * smart_pointer.h     Smart pointer, Step 2.
 *
 * Operators for negation (!), equality (==), and inequality (!=) have 
 * been added, in several specialized forms.
 */
#ifndef SMARTPOINTER_H
#define SMARTPOINTER_H
#include <algorithm>

namespace IDA_Smart_Pointer
{
   class smart_pointer
   {
   public:
      smart_pointer() = default;
      explicit smart_pointer(int* p) : ptr_{ p } {}
      smart_pointer(const smart_pointer& other) { copy(other); }
      smart_pointer(smart_pointer&& other) noexcept { swap(other); }
      ~smart_pointer() { delete ptr_; }

      smart_pointer& operator=(const smart_pointer& rhs) &
      {
	 smart_pointer{ rhs }.swap(*this);
	 return *this;
      }

      smart_pointer& operator=(smart_pointer&& rhs) & noexcept
      {
	 if (this != &rhs)
	 {
	    clear();
	    swap(rhs);
	 }
	 return *this;
      }

      smart_pointer& operator=(int* rhs)
      {
	 smart_pointer{ rhs }.swap(*this);
	 return *this;
      }

      int& operator*()  { return *ptr_; }
      
      int* operator->() { return ptr_;  }

      bool operator!() const { return ptr_ == nullptr; }

      friend bool operator==(const smart_pointer& lhs, const smart_pointer& rhs);
      friend bool operator==(const smart_pointer& lhs, const int* rhs);
      friend bool operator==(const int* lhs, const smart_pointer& rhs);

      friend bool operator!=(const smart_pointer& lhs, const smart_pointer& rhs);
      friend bool operator!=(const smart_pointer& lhs, const int* rhs);
      friend bool operator!=(const int* lhs, const smart_pointer& rhs);

      void swap(smart_pointer& other) { std::swap(ptr_, other.ptr_); }      

   private:
      int* ptr_{ nullptr };

      void copy(const smart_pointer& p)
      {
	 ptr_ = (p.ptr_ != nullptr) ? new int{ *p.ptr_ } : nullptr;
      }

      void clear() { delete ptr_; ptr_ = nullptr; }
   };

   void swap(smart_pointer& x, smart_pointer& y);

   bool operator==(const smart_pointer& lhs, const smart_pointer& rhs);
   bool operator==(const smart_pointer& lhs, const int* rhs);
   bool operator==(const int* lhs, const smart_pointer& rhs);

   bool operator!=(const smart_pointer& lhs, const smart_pointer& rhs);
   bool operator!=(const smart_pointer& lhs, const int* rhs);
   bool operator!=(const int* lhs, const smart_pointer& rhs);

} // namespace IDA_Smart_Pointer

#endif