cpp-descriptive-pointers/ptr_compare.hpp

//
//  ptr_compare.hpp
//  pointers
//
//  Created by Sam Jaffe on 1/5/17.
//

#pragma once

#define POINTER_TEMPLATE_COMPARE( ptr_t ) \
  POINTER_TEMPLATE_COMPARE_FULL( ptr_t, (typename T), (T), (typename U), (U) )

#define EXPAND( ... ) __VA_ARGS__

#define POINTER_TEMPLATE_COMPARE_FULL( ptr_t, T_tname, T, U_tname, U ) \
template <EXPAND T_tname, EXPAND U_tname> \
bool operator==(ptr_t< EXPAND T > const&lhs, ptr_t< EXPAND U > const&rhs) { \
  return lhs.get() == rhs.get(); \
} \
\
template <EXPAND T_tname, EXPAND U_tname> \
bool operator!=(ptr_t< EXPAND T > const&lhs, ptr_t< EXPAND U > const&rhs) { \
  return !(lhs == rhs); \
} \
\
template <EXPAND T_tname, EXPAND U_tname> \
bool operator< (ptr_t< EXPAND T > const&lhs, ptr_t< EXPAND U > const&rhs) { \
  typedef typename std::common_type< \
  typename ptr_t< EXPAND T >::pointer, \
  typename ptr_t< EXPAND U >::pointer>::type V; \
  return std::less<V>(lhs.get(), rhs.get()); \
} \
\
template <EXPAND T_tname, EXPAND U_tname> \
bool operator> (ptr_t< EXPAND T > const&lhs, ptr_t< EXPAND U > const&rhs) { \
  return rhs < lhs; \
} \
\
template <EXPAND T_tname, EXPAND U_tname> \
bool operator<=(ptr_t< EXPAND T > const&lhs, ptr_t< EXPAND U > const&rhs) { \
  return !(rhs < lhs); \
} \
\
template <EXPAND T_tname, EXPAND U_tname> \
bool operator>=(ptr_t< EXPAND T > const&lhs, ptr_t< EXPAND U > const&rhs) { \
  return !(lhs < rhs); \
} \
\
template <EXPAND T_tname> \
bool operator==(ptr_t< EXPAND T > const&lhs, std::nullptr_t) { \
  return !lhs; \
} \
\
template <EXPAND T_tname> \
bool operator==(std::nullptr_t, ptr_t< EXPAND T > const&rhs) { \
  return !rhs; \
} \
\
template <EXPAND T_tname> \
bool operator!=(ptr_t< EXPAND T > const&lhs, std::nullptr_t) { \
  return static_cast<bool>(lhs); \
} \
\
template <EXPAND T_tname> \
bool operator!=(std::nullptr_t, ptr_t< EXPAND T > const&rhs) { \
  return static_cast<bool>(rhs); \
} \
\
template <EXPAND T_tname> \
bool operator< (ptr_t< EXPAND T > const&lhs, std::nullptr_t) { \
  typedef typename ptr_t< EXPAND T >::pointer V; \
  return std::less<V>(lhs.get(), nullptr); \
} \
\
template <EXPAND T_tname> \
bool operator< (std::nullptr_t, ptr_t< EXPAND T > const&rhs) { \
  typedef typename ptr_t< EXPAND T >::pointer V; \
  return std::less<V>(nullptr, rhs.get()); \
} \
\
template <EXPAND T_tname> \
bool operator> (ptr_t< EXPAND T > const&lhs, std::nullptr_t) { \
  return nullptr < lhs; \
} \
\
template <EXPAND T_tname> \
bool operator> (std::nullptr_t, ptr_t< EXPAND T > const&rhs) { \
  return rhs < nullptr; \
} \
\
template <EXPAND T_tname> \
bool operator<=(ptr_t< EXPAND T > const&lhs, std::nullptr_t) { \
  return !(nullptr < lhs); \
} \
\
template <EXPAND T_tname> \
bool operator<=(std::nullptr_t, ptr_t< EXPAND T > const&rhs) { \
  return !(rhs < nullptr); \
} \
\
template <EXPAND T_tname> \
bool operator>=(ptr_t< EXPAND T > const&lhs, std::nullptr_t) { \
  return !(lhs < nullptr); \
} \
\
template <EXPAND T_tname> \
bool operator>=(std::nullptr_t, ptr_t< EXPAND T > const&rhs) { \
  return !(nullptr < rhs); \
}