memgraph/src/utils/total_ordering.hpp

#pragma once

/**
 * Implements all the logical comparison operators based on '=='
 * and '<' operators.
 *
 * @tparam TLhs First operand type.
 * @tparam TRhs Second operand type. Defaults to the same type
 * as first operand.
 * @tparam TReturn Return type, defaults to bool.
 */
template <typename TLhs, typename TRhs = TLhs, typename TReturn = bool>
struct TotalOrdering {
  virtual ~TotalOrdering() {}

  friend constexpr TReturn operator!=(const TLhs& a, const TRhs& b) {
    return !(a == b);
  }

  friend constexpr TReturn operator<=(const TLhs& a, const TRhs& b) {
    return a < b || a == b;
  }

  friend constexpr TReturn operator>(const TLhs& a, const TRhs& b) {
    return !(a <= b);
  }

  friend constexpr TReturn operator>=(const TLhs& a, const TRhs& b) {
    return !(a < b);
  }
};

template <class Derived, class T>
struct TotalOrderingWith {
  virtual ~TotalOrderingWith() {}

  friend constexpr bool operator!=(const Derived& a, const T& b) {
    return !(a == b);
  }

  friend constexpr bool operator<=(const Derived& a, const T& b) {
    return a < b || a == b;
  }

  friend constexpr bool operator>(const Derived& a, const T& b) {
    return !(a <= b);
  }

  friend constexpr bool operator>=(const Derived& a, const T& b) {
    return !(a < b);
  }

  friend constexpr bool operator!=(const T& a, const Derived& b) {
    return !(a == b);
  }

  friend constexpr bool operator<=(const T& a, const Derived& b) {
    return a < b || a == b;
  }

  friend constexpr bool operator>(const T& a, const Derived& b) {
    return !(a <= b);
  }

  friend constexpr bool operator>=(const T& a, const Derived& b) {
    return !(a < b);
  }
};