Forward declaration of variant. More...

Inheritance diagram for arene::base::variant< Ts >:

Public Member Functions
template<typename T0 = nth_type<0>, constraints< std::enable_if_t< std::is_default_constructible< T0 >::value > > = nullptr>
	variant () noexcept(std::is_nothrow_default_constructible< T0 >::value)
	Default constructor, which initializes the variant to a default constructed instance of its 0'th alternative.

	variant (copy_ctor_arg const &other) noexcept(arene::base::all_of_v< std::is_nothrow_copy_constructible< Ts >::value... >)
	Copy Constructor from another variant of the same alternative types.

	variant (dummy_copy_ctor_source const &other)=delete
	Copy Constructor from another variant of the same alternative types.

	variant (dummy_move_ctor_source &&other)=delete
	Move Constructor form another variant.

	variant (move_ctor_arg &&other) noexcept(base::all_of_v< std::is_nothrow_move_constructible< Ts >::value... >)
	Move Constructor from another variant.

template<typename T, std::size_t I = variant_detail::accepted_index<variant, T>::type::value, typename Tj = nth_type<I>, constraints< std::enable_if_t<!std::is_same< typename std::decay< T >::type, variant >::value >, std::enable_if_t< std::is_constructible< Tj, T >::value > > = nullptr>
	variant (T &&value) noexcept(std::is_nothrow_constructible< Tj, T >::value)
	Constructor that initializes this variant from one of its alternative types.

	~variant ()
	Calls the destructor of the alternative type.

template<std::size_t I, typename... Args>
auto	emplace (Args &&... args) noexcept(std::is_nothrow_constructible< nth_type< I >, Args... >::value) -> nth_type< I > &
	Emplaces a value into the variant by index.

template<typename T, typename... Args>
auto	emplace (Args &&... args) noexcept(std::is_nothrow_constructible< T, Args... >::value) -> T &
	Emplaces a value into the variant by type.

template<std::size_t I, typename U, typename... Args>
auto	emplace (std::initializer_list< U > init, Args &&... args) noexcept(std::is_nothrow_constructible< nth_type< I >, std::initializer_list< U >, Args... >::value) -> nth_type< I > &
	Emplaces a value into the variant by index.

template<typename T, typename U, typename... Args>
auto	emplace (std::initializer_list< U > init, Args &&... args) noexcept(std::is_nothrow_constructible< T, std::initializer_list< U >, Args... >::value) -> T &
	Emplaces a value into the variant by type.

template<std::size_t Index>
auto	get () &&noexcept(!detail::are_exceptions_enabled_v) -> nth_type< Index > &&
	Get the object stored in this variant by the index.

template<typename T>
auto	get () &&noexcept(!detail::are_exceptions_enabled_v) -> T &&
	Get by type.

template<std::size_t Index>
auto	get () &noexcept(!detail::are_exceptions_enabled_v) -> nth_type< Index > &
	Get the object stored in this variant by the index.

template<typename T>
auto	get () &noexcept(!detail::are_exceptions_enabled_v) -> T &
	Get by type.

template<std::size_t Index>
auto	get () const &&noexcept(!detail::are_exceptions_enabled_v) -> nth_type< Index > const &&
	Get the object stored in this variant by the index.

template<typename T>
auto	get () const &&noexcept(!detail::are_exceptions_enabled_v) -> T const &&
	Get by type.

template<std::size_t Index>
auto	get () const &noexcept(!detail::are_exceptions_enabled_v) -> nth_type< Index > const &
	Get the object stored in this variant by the index.

template<typename T>
auto	get () const &noexcept(!detail::are_exceptions_enabled_v) -> T const &
	Get by type.

auto	index () const noexcept -> std::size_t
	Get the index of the alternative type that this variant currently holds.

auto	operator= (copy_assignment_arg const &rhs) noexcept(base::all_of_v< std::is_nothrow_copy_constructible< Ts >::value... > &&base::all_of_v< std::is_nothrow_copy_assignable< Ts >::value... >) -> variant &
	Copy Assignment operator from another variant of the same alternative types.

auto	operator= (dummy_copy_assign_source const &rhs) -> variant &=delete
	Copy Assignment operator from another variant of the same alternative types.

auto	operator= (dummy_move_assign_source &&rhs) -> variant &=delete
	Move Assignment operator from another variant of the same alternative types.

auto	operator= (move_assignment_arg &&rhs) noexcept(base::all_of_v< std::is_nothrow_move_constructible< Ts >::value... > &&base::all_of_v< std::is_nothrow_move_assignable< Ts >::value... >) -> variant &
	Move Assignment operator from another variant of the same alternative types.

constexpr auto	valueless_by_exception () const noexcept -> bool
	Check if the variant is valueless.

Friends
auto	operator< (variant const &lhs, variant const &rhs) noexcept -> bool
	Less-than comparison.

auto	operator== (variant const &lhs, variant const &rhs) noexcept -> bool
	Equality comparison.

Detailed Description

template<typename... Ts>
class arene::base::variant< Ts >

Forward declaration of variant.

a backport of C++17's std::variant

Template Parameters

Ts	the types in the variant
Ts	The set of alternatives that can be held by the variant.

Constructor & Destructor Documentation

◆ variant() [1/6]

template<typename... Ts>

template<typename T0 = nth_type<0>, constraints< std::enable_if_t< std::is_default_constructible< T0 >::value > > = nullptr>

arene::base::variant< Ts >::variant ( )

inlinenoexcept

Default constructor, which initializes the variant to a default constructed instance of its 0'th alternative.

Precondition: Only participates in overload resolution if the first type in Ts is default constructible.

◆ variant() [2/6]

template<typename... Ts>

arene::base::variant< Ts >::variant ( copy_ctor_arg const & other )

inlinenoexcept

Copy Constructor from another variant of the same alternative types.

If the other variant is valueless, this variant will also be valueless.

Precondition: Only participates in overload resolution if every type in Ts is copy constructible.

Parameters

other the other variant to copy from

◆ variant() [3/6]

template<typename... Ts>

arene::base::variant< Ts >::variant ( dummy_copy_ctor_source const & other )

delete

Copy Constructor from another variant of the same alternative types.

If the other variant is valueless, this variant will also be valueless.

Precondition: Only participates in overload resolution if every type in Ts is copy constructible.

Parameters

other the other variant to copy from

◆ variant() [4/6]

template<typename... Ts>

arene::base::variant< Ts >::variant ( move_ctor_arg && other )

inlinenoexcept

Move Constructor from another variant.

If the other variant is valueless, this variant will also be valueless.

Precondition: Only participates in overload resolution if every type in Ts is move constructible.

Parameters

other the other variant to move from

◆ variant() [5/6]

template<typename... Ts>

arene::base::variant< Ts >::variant ( dummy_move_ctor_source && other )

delete

Move Constructor form another variant.

If the other variant is valueless, this variant will also be valueless.

Precondition: Only participates in overload resolution if every type in Ts is move constructible.

Parameters

other the other variant to move from

◆ variant() [6/6]

template<typename... Ts>

template<typename T, std::size_t I = variant_detail::accepted_index<variant, T>::type::value, typename Tj = nth_type<I>, constraints< std::enable_if_t<!std::is_same< typename std::decay< T >::type, variant >::value >, std::enable_if_t< std::is_constructible< Tj, T >::value > > = nullptr>

arene::base::variant< Ts >::variant ( T && value )

inlinenoexcept

Constructor that initializes this variant from one of its alternative types.

This constructor will pick the constructor overload of the alternative type Tj that T_i x[] = { std::forward<T>(value) }; is valid. If more than one alternative type satisfies this condition, the compilation will fail.

Template Parameters

T	the type to construct this variant
I	the deduced index of the alternative type that T can construct
Tj	the deduced alternative type that T can construct

Parameters

value the object to forward into the variant

◆ ~variant()

template<typename... Ts>

arene::base::variant< Ts >::~variant ( )

inline

Calls the destructor of the alternative type.

Member Function Documentation

◆ emplace() [1/4]

template<typename... Ts>

template<std::size_t I, typename... Args>

auto arene::base::variant< Ts >::emplace ( Args &&... args ) -> nth_type<I>&

inlinenoexcept

Emplaces a value into the variant by index.

Template Parameters

I	the index of the alternative type to emplace
Args	the variadic argument type to pass into the constructor of the alternative type

Parameters

args	Arguments to be forwarded to the constructor of the emplaced type.

Returns: A reference to the emplaced object.

Postcondition: If the variant was not valueless, the currently held value is destroyed; The variant will hold the value the returned reference points to.; holds_alternative<I>(*this) will return true; index() will return I

◆ emplace() [2/4]

template<typename... Ts>

template<typename T, typename... Args>

auto arene::base::variant< Ts >::emplace ( Args &&... args ) -> T&

inlinenoexcept

Emplaces a value into the variant by type.

Template Parameters

T	the alternative type to emplace

Parameters

args	Arguments to be forwarded to the constructor of the emplaced type.

Returns: A reference to the emplaced object.

Postcondition: If the variant was not valueless, the currently held value is destroyed; The variant will hold the value the returned reference points to.; holds_alternative<T>(*this) will return true; index() will return the the equivalent of index_of_v<T, Ts...>

◆ emplace() [3/4]

template<typename... Ts>

template<std::size_t I, typename U, typename... Args>

auto arene::base::variant< Ts >::emplace	(	std::initializer_list< U >	init,
		Args &&...	args ) -> nth_type<I>&

inlinenoexcept

Emplaces a value into the variant by index.

Template Parameters

I	the index of the alternative type to emplace
Args	the variadic argument type to pass into the constructor of the alternative type

Parameters

init	An initializer list to forward to the constructor of the emplaced type.
args	Arguments to be forwarded to the constructor of the emplaced type.

Returns: A reference to the emplaced object.

Postcondition: If the variant was not valueless, the currently held value is destroyed; The variant will hold the value the returned reference points to.; holds_alternative<I>(*this) will return true; index() will return I

◆ emplace() [4/4]

template<typename... Ts>

template<typename T, typename U, typename... Args>

auto arene::base::variant< Ts >::emplace	(	std::initializer_list< U >	init,
		Args &&...	args ) -> T&

inlinenoexcept

Emplaces a value into the variant by type.

Template Parameters

T	the alternative type to emplace

Parameters

init	An initializer list to forward to the constructor of the emplaced type.
args	Arguments to be forwarded to the constructor of the emplaced type.

Returns: A reference to the emplaced object.

Postcondition: If the variant was not valueless, the currently held value is destroyed; The variant will hold the value the returned reference points to.; holds_alternative<T>(*this) will return true; index() will return the the equivalent of index_of_v<T, Ts...>

◆ get() [1/8]

template<typename... Ts>

template<std::size_t Index>

auto arene::base::variant< Ts >::get ( ) && -> nth_type<Index>&&

inlinenoexcept

Get the object stored in this variant by the index.

Template Parameters

Index the index into Ts of the alternative to get

Exceptions

bad_variant_access if ARENE_IS_ON(ARENE_EXCEPTIONS_ENABLED) and if the type index of the object currently held by the variant does not match the index requested.

Precondition: If ARENE_IS_OFF(ARENE_EXCEPTIONS_ENABLED) the type index of the object currently held by the variant must match the type requested else ARENE_PRECONDITION violation.

Returns: nth_type<Index>&& The reference to the held object.

◆ get() [2/8]

template<typename... Ts>

template<typename T>

auto arene::base::variant< Ts >::get ( ) && -> T&&

inlinenoexcept

Get by type.

Template Parameters

T	the alternative type to get

Exceptions

bad_variant_access if ARENE_IS_ON(ARENE_EXCEPTIONS_ENABLED) and if the type of the object currently held by the variant does not match the type requested.

Precondition: If ARENE_IS_OFF(ARENE_EXCEPTIONS_ENABLED) the type of the object currently held by the variant must match the type requested else ARENE_PRECONDITION violation.

Returns: T&& The reference to the held object.

◆ get() [3/8]

template<typename... Ts>

template<std::size_t Index>

auto arene::base::variant< Ts >::get ( ) & -> nth_type<Index>&

inlinenoexcept

Get the object stored in this variant by the index.

Template Parameters

Index the index into Ts of the alternative to get

Exceptions

bad_variant_access if ARENE_IS_ON(ARENE_EXCEPTIONS_ENABLED) and if the type index of the object currently held by the variant does not match the index requested.

Precondition: If ARENE_IS_OFF(ARENE_EXCEPTIONS_ENABLED) the type index of the object currently held by the variant must match the type requested else ARENE_PRECONDITION violation.

Returns: nth_type<Index>& The reference to the held object.

◆ get() [4/8]

template<typename... Ts>

template<typename T>

auto arene::base::variant< Ts >::get ( ) & -> T&

inlinenoexcept

Get by type.

Template Parameters

T	the alternative type to get

Exceptions

bad_variant_access if ARENE_IS_ON(ARENE_EXCEPTIONS_ENABLED) and if the type of the object currently held by the variant does not match the type requested.

Precondition: If ARENE_IS_OFF(ARENE_EXCEPTIONS_ENABLED) the type of the object currently held by the variant must match the type requested else ARENE_PRECONDITION violation.

Returns: T& The reference to the held object.

◆ get() [5/8]

template<typename... Ts>

template<std::size_t Index>

auto arene::base::variant< Ts >::get ( ) const && -> nth_type<Index> const&&

inlinenoexcept

Get the object stored in this variant by the index.

Template Parameters

Index the index into Ts of the alternative to get

Exceptions

bad_variant_access if ARENE_IS_ON(ARENE_EXCEPTIONS_ENABLED) and if the type index of the object currently held by the variant does not match the index requested.

Precondition: If ARENE_IS_OFF(ARENE_EXCEPTIONS_ENABLED) the type index of the object currently held by the variant must match the type requested else ARENE_PRECONDITION violation.

Returns: nth_type<Index> const&& The reference to the held object.

◆ get() [6/8]

template<typename... Ts>

template<typename T>

auto arene::base::variant< Ts >::get ( ) const && -> T const&&

inlinenoexcept

Get by type.

Template Parameters

T	the alternative type to get

Exceptions

bad_variant_access if ARENE_IS_ON(ARENE_EXCEPTIONS_ENABLED) and if the type of the object currently held by the variant does not match the type requested.

Precondition: If ARENE_IS_OFF(ARENE_EXCEPTIONS_ENABLED) the type of the object currently held by the variant must match the type requested else ARENE_PRECONDITION violation.

Returns: T const&& The reference to the held object.

◆ get() [7/8]

template<typename... Ts>

template<std::size_t Index>

auto arene::base::variant< Ts >::get ( ) const & -> nth_type<Index> const&

inlinenoexcept

Get the object stored in this variant by the index.

Template Parameters

Index the index into Ts of the alternative to get

Exceptions

bad_variant_access if ARENE_IS_ON(ARENE_EXCEPTIONS_ENABLED) and if the type index of the object currently held by the variant does not match the index requested.

Precondition: If ARENE_IS_OFF(ARENE_EXCEPTIONS_ENABLED) the type index of the object currently held by the variant must match the type requested else ARENE_PRECONDITION violation.

Returns: nth_type<Index> const& The reference to the held object.

◆ get() [8/8]

template<typename... Ts>

template<typename T>

auto arene::base::variant< Ts >::get ( ) const & -> T const&

inlinenoexcept

Get by type.

Template Parameters

T	the alternative type to get

Exceptions

bad_variant_access if ARENE_IS_ON(ARENE_EXCEPTIONS_ENABLED) and if the type of the object currently held by the variant does not match the type requested.

Precondition: If ARENE_IS_OFF(ARENE_EXCEPTIONS_ENABLED) the type of the object currently held by the variant must match the type requested else ARENE_PRECONDITION violation.

Returns: T const& The reference to the held object.

◆ index()

template<typename... Ts>

auto arene::base::variant< Ts >::index ( ) const -> std::size_t

inlinenoexcept

Get the index of the alternative type that this variant currently holds.

Returns: std::size_t the index of the alternative type that this variant currently holds, or variant_npos if the variant is valueless.

◆ operator=() [1/4]

template<typename... Ts>

auto arene::base::variant< Ts >::operator= ( copy_assignment_arg const & rhs ) -> variant&

inlinenoexcept

Copy Assignment operator from another variant of the same alternative types.

If the other type is valueless, or exception is thrown during copying, this variant will also be valueless.

Precondition: Only participates in overload resolution if every type in Ts is copy-assignable.

Parameters

rhs	the other variant to copy from

◆ operator=() [2/4]

template<typename... Ts>

auto arene::base::variant< Ts >::operator= ( dummy_copy_assign_source const & rhs ) -> variant &=delete

delete

Copy Assignment operator from another variant of the same alternative types.

If the other type is valueless, or exception is thrown during copying, this variant will also be valueless.

Precondition: Only participates in overload resolution if every type in Ts is copy-assignable.

Parameters

rhs	the other variant to copy from

◆ operator=() [3/4]

template<typename... Ts>

auto arene::base::variant< Ts >::operator= ( dummy_move_assign_source && rhs ) -> variant &=delete

delete

Move Assignment operator from another variant of the same alternative types.

If the other type is valueless, this variant will also be valueless.

Precondition: Only participates in overload resolution if every type in Ts is move-assignable.

Parameters

rhs	the other variant to move from

◆ operator=() [4/4]

template<typename... Ts>

auto arene::base::variant< Ts >::operator= ( move_assignment_arg && rhs ) -> variant&

inlinenoexcept

Move Assignment operator from another variant of the same alternative types.

If the other type is valueless, this variant will also be valueless.

Precondition: Only participates in overload resolution if every type in Ts is move-assignable.

Parameters

rhs	the other variant to move from

◆ valueless_by_exception()

template<typename... Ts>

auto arene::base::variant< Ts >::valueless_by_exception ( ) const -> bool

inlineconstexprnoexcept

Check if the variant is valueless.

A variant becomes valueless if and only if an exception is thrown during copy or move initialization

Returns: true if the variant does not hold a value; false if the variant holds a value.

Friends And Related Symbol Documentation

◆ operator<

template<typename... Ts>

auto operator<	(	variant< Ts > const &	lhs,
		variant< Ts > const &	rhs ) -> bool

friend

Less-than comparison.

Precondition: The behavior is undefined if not all the alternatives support less than comparison.

Parameters

lhs	variant to compare
rhs	the other variant to compare

Returns: false if either variant is valueless; Otherwise, returns the result of invoking std::less on the held alternatives of the two variants.

◆ operator==

template<typename... Ts>

auto operator==	(	variant< Ts > const &	lhs,
		variant< Ts > const &	rhs ) -> bool

friend

Equality comparison.

Precondition: The behavior is undefined if not all the alternatives support equality comparison.

Parameters

lhs	variant to compare
rhs	the other variant to compare

Returns: true if both variants are valueless, or both variants hold the same alternative type and the value of that alternative type is equal.; false otherwise.

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

arene/base/variant/traits.hpp
arene/base/variant/variant.hpp

Public Member Functions

Friends

Detailed Description

Constructor & Destructor Documentation

◆ variant() [1/6]

◆ variant() [2/6]

◆ variant() [3/6]

◆ variant() [4/6]

◆ variant() [5/6]

◆ variant() [6/6]

◆ ~variant()

Member Function Documentation

◆ emplace() [1/4]

◆ emplace() [2/4]

◆ emplace() [3/4]

◆ emplace() [4/4]

◆ get() [1/8]

◆ get() [2/8]

◆ get() [3/8]

◆ get() [4/8]

◆ get() [5/8]

◆ get() [6/8]

◆ get() [7/8]

◆ get() [8/8]

◆ index()

◆ operator=() [1/4]

◆ operator=() [2/4]

◆ operator=() [3/4]

◆ operator=() [4/4]

◆ valueless_by_exception()

Friends And Related Symbol Documentation

◆ operator<

◆ operator==