arene::base::generic_ordering_from_three_way_compare_and_equals< Derived > Class Template Reference

Helper class that can be inherited from by a class to define the relational comparison operators in terms of a three_way_compare function provided by the Derived class, but preferentially implementing == and != to use operator==(Derived, Other) rather than three_way_compare. More...

Inheritance diagram for arene::base::generic_ordering_from_three_way_compare_and_equals< Derived >:

Protected Member Functions
constexpr	generic_ordering_from_three_way_compare_and_equals () noexcept=default
	Default constructor is protected.
constexpr	generic_ordering_from_three_way_compare_and_equals (generic_ordering_from_three_way_compare_and_equals &&other) noexcept=default
	Default move constructor is protected.
constexpr	generic_ordering_from_three_way_compare_and_equals (generic_ordering_from_three_way_compare_and_equals const &other) noexcept=default
	Default copy constructor is protected.
	~generic_ordering_from_three_way_compare_and_equals () noexcept=default
	Default destructor is protected.
constexpr auto	operator= (generic_ordering_from_three_way_compare_and_equals &&other) &noexcept -> generic_ordering_from_three_way_compare_and_equals &=default
	Default move assignment is protected.
constexpr auto	operator= (generic_ordering_from_three_way_compare_and_equals const &other) &noexcept -> generic_ordering_from_three_way_compare_and_equals &=default
	Default copy assignment is protected.

Friends
template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< operators_detail::eligible_for_reversed_equals_with_v< Self, Other > > > = nullptr>
ARENE_NODISCARD friend constexpr auto	operator!= (Other const &lhs, Self const &rhs) noexcept -> bool
	Inequality comparison operator for instances of Derived with Other.
template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_equality_comparable_v< Self, Other > > > = nullptr>
ARENE_NODISCARD friend constexpr auto	operator!= (Self const &lhs, Other const &rhs) noexcept -> bool
	Inequality comparison operator for instances of Derived with Other.
template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > >, std::enable_if_t<!is_three_way_comparable_v< Other, Derived > > > = nullptr>
ARENE_NODISCARD friend constexpr auto	operator< (Other const &lhs, Self const &rhs) noexcept -> bool
	Less-than comparison operator for instances of Derived with Other.
template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > > > = nullptr>
ARENE_NODISCARD friend constexpr auto	operator< (Self const &lhs, Other const &rhs) noexcept -> bool
	Less-than comparison operator for instances of Derived with Other.
template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > >, std::enable_if_t<!is_three_way_comparable_v< Other, Derived > > > = nullptr>
ARENE_NODISCARD friend constexpr auto	operator<= (Other const &lhs, Self const &rhs) noexcept -> bool
	Less-than-or-equal comparison operator for instances of Derived with Other.
template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > > > = nullptr>
ARENE_NODISCARD friend constexpr auto	operator<= (Self const &lhs, Other const &rhs) noexcept -> bool
	Less-than-or-equal comparison operator for instances of Derived with Other.
template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< operators_detail::eligible_for_reversed_equals_with_v< Self, Other > > > = nullptr>
ARENE_NODISCARD friend constexpr auto	operator== (Other const &lhs, Self const &rhs) noexcept -> bool
	Equality comparison operator for instances of Derived with Other.
template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > >, std::enable_if_t<!is_three_way_comparable_v< Other, Derived > > > = nullptr>
ARENE_NODISCARD friend constexpr auto	operator> (Other const &lhs, Self const &rhs) noexcept -> bool
	Greater-than comparison operator for instances of Derived with Other.
template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > > > = nullptr>
ARENE_NODISCARD friend constexpr auto	operator> (Self const &lhs, Other const &rhs) noexcept -> bool
	Greater-than comparison operator for instances of Derived with Other.
template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > >, std::enable_if_t<!is_three_way_comparable_v< Other, Derived > > > = nullptr>
ARENE_NODISCARD friend constexpr auto	operator>= (Other const &lhs, Self const &rhs) noexcept -> bool
	Greater-than-or-equal comparison operator for instances of Derived with Other.
template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > > > = nullptr>
ARENE_NODISCARD friend constexpr auto	operator>= (Self const &lhs, Other const &rhs) noexcept -> bool
	Greater-than-or-equal comparison operator for instances of Derived with Other.

Detailed Description

template<typename Derived>
class arene::base::generic_ordering_from_three_way_compare_and_equals< Derived >

Helper class that can be inherited from by a class to define the relational comparison operators in terms of a three_way_compare function provided by the Derived class, but preferentially implementing == and != to use operator==(Derived, Other) rather than three_way_compare.

Generates the <, >, <=, and >= comparison operators from a possibly overloaded static member function three_way_compare in the Derived class that accepts a const Derived& as the first argument and any other type as the second argument, and returns a strong_ordering value indicating whether the first is less than, equal to or greater than the second. These three_way_compare functions must not throw exceptions.

Even if the derived class provides a fast_inequality_check function, it is not used, because the exact operator== is preferred over three_way_compare.

Template Parameters

Derived

The type of the derived class. The comparison operators provided take parameters of this type.

For example:

/// @brief An example string-like class with generated comparison operations
class string_like : arene::base::generic_ordering_from_three_way_compare_and_equals<string_like> {
 public:
  /// @brief a three-way ordering function for two @c string_like instances
  /// @param lhs The first object being compared
  /// @param rhs The second object being compared
  /// @return arene::base::strong_ordering holding the result of the comparison
  ARENE_NODISCARD static arene::base::strong_ordering
  three_way_compare(string_like const& lhs, string_like const& rhs) noexcept {
    return real_comparison(lhs, rhs);
  }
  /// @brief a three-way ordering function for a @c string_like object with a @c arene::base::string_view object
  /// @param lhs The first object being compared
  /// @param rhs The second object being compared
  /// @return arene::base::strong_ordering holding the result of the comparison
  ARENE_NODISCARD static arene::base::strong_ordering
  three_way_compare(string_like const& lhs, arene::base::string_view rhs) noexcept {
    return real_comparison(lhs, rhs);
  }
 
  /// @brief a three-way ordering function for a @c string_like object with a @c
  /// arene::base::null_terminated_string_view object
  /// @param lhs The first object being compared
  /// @param rhs The second object being compared
  /// @return arene::base::strong_ordering holding the result of the comparison
  ARENE_NODISCARD static arene::base::strong_ordering
  three_way_compare(string_like const& lhs, arene::base::null_terminated_string_view rhs) noexcept {
    return real_comparison(lhs, rhs);
  }
 
  /// @brief A fast inequality check for two @c string_like types to avoid character-by-character comparisons if they
  /// have different lengths
  /// @param lhs The first object being compared
  /// @param rhs The second object being compared
  /// @return arene::base::inequality_heuristic which is @c arene::base::inequality_heuristic::definitely_not_equal if
  /// the strings have different lengths and @c arene::base::inequality_heuristic::may_be_equal_or_not_equal otherwise
  ARENE_NODISCARD friend bool operator==(string_like const& lhs, arene::base::string_view rhs) noexcept {
    return to_string_view(lhs) == rhs;
  }
 
  /// @brief A fast inequality check for two @c string_like types to avoid character-by-character comparisons if they
  /// @param lhs The first object being compared
  /// @param rhs The second object being compared
  /// @return arene::base::inequality_heuristic which is @c arene::base::inequality_heuristic::definitely_not_equal if
  /// the strings have different lengths and @c arene::base::inequality_heuristic::may_be_equal_or_not_equal otherwise
  ARENE_NODISCARD friend bool operator==(string_like const& lhs, string_like const& rhs) noexcept {
    return lhs == to_string_view(rhs);
  }
};

Here, MyClass has comparison operators for comparing instances of MyClass with each other, or with OtherClass, or with YetAnotherClass. Equality comparisons with OtherClass will use operator==, while comparisons with YetAnotherClass will use three_way_compare.

Constructor & Destructor Documentation

generic_ordering_from_three_way_compare_and_equals() [1/3]

template<typename Derived>

arene::base::generic_ordering_from_three_way_compare_and_equals< Derived >::generic_ordering_from_three_way_compare_and_equals ( )

constexprprotecteddefaultnoexcept

Default constructor is protected.

~generic_ordering_from_three_way_compare_and_equals()

template<typename Derived>

arene::base::generic_ordering_from_three_way_compare_and_equals< Derived >::~generic_ordering_from_three_way_compare_and_equals ( )

protecteddefaultnoexcept

Default destructor is protected.

generic_ordering_from_three_way_compare_and_equals() [2/3]

template<typename Derived>

arene::base::generic_ordering_from_three_way_compare_and_equals< Derived >::generic_ordering_from_three_way_compare_and_equals ( generic_ordering_from_three_way_compare_and_equals< Derived > const & other )

constexprprotecteddefaultnoexcept

Default copy constructor is protected.

Parameters

other

The source object

generic_ordering_from_three_way_compare_and_equals() [3/3]

template<typename Derived>

arene::base::generic_ordering_from_three_way_compare_and_equals< Derived >::generic_ordering_from_three_way_compare_and_equals ( generic_ordering_from_three_way_compare_and_equals< Derived > && other )

constexprprotecteddefaultnoexcept

Default move constructor is protected.

Parameters

other

The source object

Member Function Documentation

operator=() [1/2]

template<typename Derived>

auto arene::base::generic_ordering_from_three_way_compare_and_equals< Derived >::operator= ( generic_ordering_from_three_way_compare_and_equals< Derived > && other ) & -> generic_ordering_from_three_way_compare_and_equals &=default

constexprprotecteddefaultnoexcept

Default move assignment is protected.

Parameters

other

The source object

operator=() [2/2]

template<typename Derived>

auto arene::base::generic_ordering_from_three_way_compare_and_equals< Derived >::operator= ( generic_ordering_from_three_way_compare_and_equals< Derived > const & other ) & -> generic_ordering_from_three_way_compare_and_equals &=default

constexprprotecteddefaultnoexcept

Default copy assignment is protected.

Parameters

other

The source object

Friends And Related Symbol Documentation

operator!= [1/2]

template<typename Derived>

template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< operators_detail::eligible_for_reversed_equals_with_v< Self, Other > > > = nullptr>

ARENE_NODISCARD friend constexpr auto operator!= ( Other const & lhs, Self const & rhs ) -> bool

friend

Inequality comparison operator for instances of Derived with Other.

Template Parameters

Self	the type of the Derived object to compare, used for constraints
Other	the type of the object to compare to

Parameters

lhs	The instance of Derived to compare
rhs	The instance of Other to compare

Returns

bool true if lhs is not equal to rhs, false otherwise

operator!= [2/2]

template<typename Derived>

template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_equality_comparable_v< Self, Other > > > = nullptr>

ARENE_NODISCARD friend constexpr auto operator!= ( Self const & lhs, Other const & rhs ) -> bool

friend

Inequality comparison operator for instances of Derived with Other.

Template Parameters

Self	the type of the Derived object to compare, used for constraints
Other	the type of the object to compare to

Parameters

lhs	The instance of Derived to compare
rhs	The instance of Other to compare

Returns

bool true if lhs is not equal to rhs, false otherwise

operator< [1/2]

template<typename Derived>

template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > >, std::enable_if_t<!is_three_way_comparable_v< Other, Derived > > > = nullptr>

ARENE_NODISCARD friend constexpr auto operator< ( Other const & lhs, Self const & rhs ) -> bool

friend

Less-than comparison operator for instances of Derived with Other.

Template Parameters

Self	the type of the Derived object to compare, used for constraints
Other	The type of the object to compare to

Parameters

lhs	The instance of Other to compare
rhs	The instance of Derived to compare

Returns

bool true if lhs is less than rhs, false otherwise

operator< [2/2]

template<typename Derived>

template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > > > = nullptr>

ARENE_NODISCARD friend constexpr auto operator< ( Self const & lhs, Other const & rhs ) -> bool

friend

Less-than comparison operator for instances of Derived with Other.

Template Parameters

Self	the type of the Derived object to compare, used for constraints
Other	the type of the object to compare to

Parameters

lhs	The instance of Derived to compare
rhs	The instance of Other to compare

Returns

bool true if lhs is less than rhs, false otherwise

operator<= [1/2]

template<typename Derived>

template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > >, std::enable_if_t<!is_three_way_comparable_v< Other, Derived > > > = nullptr>

ARENE_NODISCARD friend constexpr auto operator<= ( Other const & lhs, Self const & rhs ) -> bool

friend

Less-than-or-equal comparison operator for instances of Derived with Other.

Template Parameters

Self	the type of the Derived object to compare, used for constraints
Other	the type of the object to compare to

Parameters

lhs	The instance of Other to compare
rhs	The instance of Derived to compare

Returns

bool true if lhs is less than or equal to rhs, false otherwise

operator<= [2/2]

template<typename Derived>

template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > > > = nullptr>

ARENE_NODISCARD friend constexpr auto operator<= ( Self const & lhs, Other const & rhs ) -> bool

friend

Less-than-or-equal comparison operator for instances of Derived with Other.

Template Parameters

Self	the type of the Derived object to compare, used for constraints
Other	the type of the object to compare to

Parameters

lhs	The instance of Derived to compare
rhs	The instance of Other to compare

Returns

bool true if lhs is less than or equal to rhs, false otherwise

operator==

template<typename Derived>

template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< operators_detail::eligible_for_reversed_equals_with_v< Self, Other > > > = nullptr>

ARENE_NODISCARD friend constexpr auto operator== ( Other const & lhs, Self const & rhs ) -> bool

friend

Equality comparison operator for instances of Derived with Other.

Template Parameters

Self	the type of the Derived object to compare, used for constraints
Other	the type of the object to compare to

Parameters

lhs	The instance of Derived to compare
rhs	The instance of Other to compare

Returns

bool true if lhs is equal to rhs, false otherwise

operator> [1/2]

template<typename Derived>

template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > >, std::enable_if_t<!is_three_way_comparable_v< Other, Derived > > > = nullptr>

ARENE_NODISCARD friend constexpr auto operator> ( Other const & lhs, Self const & rhs ) -> bool

friend

Greater-than comparison operator for instances of Derived with Other.

Template Parameters

Self	the type of the Derived object to compare, used for constraints
Other	the type of the object to compare to

Parameters

lhs	The instance of Other to compare
rhs	The instance of Derived to compare

Returns

bool true if lhs is greater than rhs, false otherwise

operator> [2/2]

template<typename Derived>

template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > > > = nullptr>

ARENE_NODISCARD friend constexpr auto operator> ( Self const & lhs, Other const & rhs ) -> bool

friend

Greater-than comparison operator for instances of Derived with Other.

Template Parameters

Self	the type of the Derived object to compare, used for constraints
Other	the type of the object to compare to

Parameters

lhs	The instance of Derived to compare
rhs	The instance of Other to compare

Returns

bool true if lhs is greater than rhs, false otherwise

operator>= [1/2]

template<typename Derived>

template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > >, std::enable_if_t<!is_three_way_comparable_v< Other, Derived > > > = nullptr>

ARENE_NODISCARD friend constexpr auto operator>= ( Other const & lhs, Self const & rhs ) -> bool

friend

Greater-than-or-equal comparison operator for instances of Derived with Other.

Template Parameters

Self	the type of the Derived object to compare, used for constraints
Other	the type of the object to compare to

Parameters

lhs	The instance of Other to compare
rhs	The instance of Derived to compare

Returns

bool true if lhs is greater than or equal to rhs, false otherwise

operator>= [2/2]

template<typename Derived>

template<typename Self, typename Other, constraints< std::enable_if_t< std::is_same< Self, Derived >::value >, std::enable_if_t< is_three_way_comparable_v< Derived, Other > > > = nullptr>

ARENE_NODISCARD friend constexpr auto operator>= ( Self const & lhs, Other const & rhs ) -> bool

friend

Greater-than-or-equal comparison operator for instances of Derived with Other.

Template Parameters

Self	the type of the Derived object to compare, used for constraints
Other	the type of the object to compare to

Parameters

lhs	The instance of Derived to compare
rhs	The instance of Other to compare

Returns

bool true if lhs is greater than or equal to rhs, false otherwise

---

The documentation for this class was generated from the following file:

• arene/base/compare/operators.hpp