// MPark.Variant
//
// Copyright Michael Park, 2015-2017
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
#ifndef MPARK_VARIANT_HPP
#define MPARK_VARIANT_HPP
/*
variant synopsis
namespace std {
// 20.7.2, class template variant
template <class... Types>
class variant {
public:
// 20.7.2.1, constructors
constexpr variant() noexcept(see below);
variant(const variant&);
variant(variant&&) noexcept(see below);
template <class T> constexpr variant(T&&) noexcept(see below);
template <class T, class... Args>
constexpr explicit variant(in_place_type_t<T>, Args&&...);
template <class T, class U, class... Args>
constexpr explicit variant(
in_place_type_t<T>, initializer_list<U>, Args&&...);
template <size_t I, class... Args>
constexpr explicit variant(in_place_index_t<I>, Args&&...);
template <size_t I, class U, class... Args>
constexpr explicit variant(
in_place_index_t<I>, initializer_list<U>, Args&&...);
// 20.7.2.2, destructor
~variant();
// 20.7.2.3, assignment
variant& operator=(const variant&);
variant& operator=(variant&&) noexcept(see below);
template <class T> variant& operator=(T&&) noexcept(see below);
// 20.7.2.4, modifiers
template <class T, class... Args>
T& emplace(Args&&...);
template <class T, class U, class... Args>
T& emplace(initializer_list<U>, Args&&...);
template <size_t I, class... Args>
variant_alternative<I, variant>& emplace(Args&&...);
template <size_t I, class U, class... Args>
variant_alternative<I, variant>& emplace(initializer_list<U>, Args&&...);
// 20.7.2.5, value status
constexpr bool valueless_by_exception() const noexcept;
constexpr size_t index() const noexcept;
// 20.7.2.6, swap
void swap(variant&) noexcept(see below);
};
// 20.7.3, variant helper classes
template <class T> struct variant_size; // undefined
template <class T>
constexpr size_t variant_size_v = variant_size<T>::value;
template <class T> struct variant_size<const T>;
template <class T> struct variant_size<volatile T>;
template <class T> struct variant_size<const volatile T>;
template <class... Types>
struct variant_size<variant<Types...>>;
template <size_t I, class T> struct variant_alternative; // undefined
template <size_t I, class T>
using variant_alternative_t = typename variant_alternative<I, T>::type;
template <size_t I, class T> struct variant_alternative<I, const T>;
template <size_t I, class T> struct variant_alternative<I, volatile T>;
template <size_t I, class T> struct variant_alternative<I, const volatile T>;
template <size_t I, class... Types>
struct variant_alternative<I, variant<Types...>>;
constexpr size_t variant_npos = -1;
// 20.7.4, value access
template <class T, class... Types>
constexpr bool holds_alternative(const variant<Types...>&) noexcept;
template <size_t I, class... Types>
constexpr variant_alternative_t<I, variant<Types...>>&
get(variant<Types...>&);
template <size_t I, class... Types>
constexpr variant_alternative_t<I, variant<Types...>>&&
get(variant<Types...>&&);
template <size_t I, class... Types>
constexpr variant_alternative_t<I, variant<Types...>> const&
get(const variant<Types...>&);
template <size_t I, class... Types>
constexpr variant_alternative_t<I, variant<Types...>> const&&
get(const variant<Types...>&&);
template <class T, class... Types>
constexpr T& get(variant<Types...>&);
template <class T, class... Types>
constexpr T&& get(variant<Types...>&&);
template <class T, class... Types>
constexpr const T& get(const variant<Types...>&);
template <class T, class... Types>
constexpr const T&& get(const variant<Types...>&&);
template <size_t I, class... Types>
constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>>
get_if(variant<Types...>*) noexcept;
template <size_t I, class... Types>
constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>>
get_if(const variant<Types...>*) noexcept;
template <class T, class... Types>
constexpr add_pointer_t<T>
get_if(variant<Types...>*) noexcept;
template <class T, class... Types>
constexpr add_pointer_t<const T>
get_if(const variant<Types...>*) noexcept;
// 20.7.5, relational operators
template <class... Types>
constexpr bool operator==(const variant<Types...>&, const variant<Types...>&);
template <class... Types>
constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&);
template <class... Types>
constexpr bool operator<(const variant<Types...>&, const variant<Types...>&);
template <class... Types>
constexpr bool operator>(const variant<Types...>&, const variant<Types...>&);
template <class... Types>
constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&);
template <class... Types>
constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&);
// 20.7.6, visitation
template <class Visitor, class... Variants>
constexpr see below visit(Visitor&&, Variants&&...);
// 20.7.7, class monostate
struct monostate;
// 20.7.8, monostate relational operators
constexpr bool operator<(monostate, monostate) noexcept;
constexpr bool operator>(monostate, monostate) noexcept;
constexpr bool operator<=(monostate, monostate) noexcept;
constexpr bool operator>=(monostate, monostate) noexcept;
constexpr bool operator==(monostate, monostate) noexcept;
constexpr bool operator!=(monostate, monostate) noexcept;
// 20.7.9, specialized algorithms
template <class... Types>
void swap(variant<Types...>&, variant<Types...>&) noexcept(see below);
// 20.7.10, class bad_variant_access
class bad_variant_access;
// 20.7.11, hash support
template <class T> struct hash;
template <class... Types> struct hash<variant<Types...>>;
template <> struct hash<monostate>;
} // namespace std
*/
#include <cstddef>
#include <exception>
#include <functional>
#include <initializer_list>
#include <new>
#include <type_traits>
#include <utility>
#include "config.hpp"
#include "in_place.hpp"
#include "lib.hpp"
namespace mpark {
#ifdef MPARK_RETURN_TYPE_DEDUCTION
#define AUTO auto
#define AUTO_RETURN(...) { return __VA_ARGS__; }
#define AUTO_REFREF auto &&
#define AUTO_REFREF_RETURN(...) { return __VA_ARGS__; }
#define DECLTYPE_AUTO decltype(auto)
#define DECLTYPE_AUTO_RETURN(...) { return __VA_ARGS__; }
#else
#define AUTO auto
#define AUTO_RETURN(...) \
-> lib::decay_t<decltype(__VA_ARGS__)> { return __VA_ARGS__; }
#define AUTO_REFREF auto
#define AUTO_REFREF_RETURN(...) \
-> decltype((__VA_ARGS__)) { \
static_assert(std::is_reference<decltype((__VA_ARGS__))>::value, ""); \
return __VA_ARGS__; \
}
#define DECLTYPE_AUTO auto
#define DECLTYPE_AUTO_RETURN(...) \
-> decltype(__VA_ARGS__) { return __VA_ARGS__; }
#endif
class bad_variant_access : public std::exception {
public:
virtual const char *what() const noexcept { return "bad_variant_access"; }
};
[[noreturn]] inline void throw_bad_variant_access() {
#ifdef MPARK_EXCEPTIONS
throw bad_variant_access{};
#else
std::terminate();
#endif
}
template <typename... Ts>
class variant;
template <typename T>
struct variant_size;
#ifdef MPARK_VARIABLE_TEMPLATES
template <typename T>
constexpr std::size_t variant_size_v = variant_size<T>::value;
#endif
template <typename T>
struct variant_size<const T> : variant_size<T> {};
template <typename T>
struct variant_size<volatile T> : variant_size<T> {};
template <typename T>
struct variant_size<const volatile T> : variant_size<T> {};
template <typename... Ts>
struct variant_size<variant<Ts...>> : lib::size_constant<sizeof...(Ts)> {};
template <std::size_t I, typename T>
struct variant_alternative;
template <std::size_t I, typename T>
using variant_alternative_t = typename variant_alternative<I, T>::type;
template <std::size_t I, typename T>
struct variant_alternative<I, const T>
: std::add_const<variant_alternative_t<I, T>> {};
template <std::size_t I, typename T>
struct variant_alternative<I, volatile T>
: std::add_volatile<variant_alternative_t<I, T>> {};
template <std::size_t I, typename T>
struct variant_alternative<I, const volatile T>
: std::add_cv<variant_alternative_t<I, T>> {};
template <std::size_t I, typename... Ts>
struct variant_alternative<I, variant<Ts...>> {
static_assert(I < sizeof...(Ts),
"Index out of bounds in std::variant_alternative<>");
using type = lib::type_pack_element_t<I, Ts...>;
};
constexpr std::size_t variant_npos = static_cast<std::size_t>(-1);
namespace detail {
inline constexpr bool all() { return true; }
template <typename... Bs>
inline constexpr bool all(bool b, Bs... bs) {
return b && all(bs...);
}
constexpr std::size_t not_found = static_cast<std::size_t>(-1);
constexpr std::size_t ambiguous = static_cast<std::size_t>(-2);
#ifdef MPARK_CPP14_CONSTEXPR
template <typename T, typename... Ts>
inline constexpr std::size_t find_index() {
constexpr lib::array<bool, sizeof...(Ts)> matches = {
{std::is_same<T, Ts>::value...}
};
std::size_t result = not_found;
for (std::size_t i = 0; i < sizeof...(Ts); ++i) {
if (matches[i]) {
if (result != not_found) {
return ambiguous;
}
result = i;
}
}
return result;
}
#else
inline constexpr std::size_t find_index_impl(std::size_t result,
std::size_t) {
return result;
}
template <typename... Bs>
inline constexpr std::size_t find_index_impl(std::size_t result,
std::size_t idx,
bool b,
Bs... bs) {
return b ? (result != not_found ? ambiguous
: find_index_impl(idx, idx + 1, bs...))
: find_index_impl(result, idx + 1, bs...);
}
template <typename T, typename... Ts>
inline constexpr std::size_t find_index() {
return find_index_impl(not_found, 0, std::is_same<T, Ts>::value...);
}
#endif
template <std::size_t I>
using find_index_sfinae_impl =
lib::enable_if_t<I != not_found && I != ambiguous,
lib::size_constant<I>>;
template <typename T, typename... Ts>
using find_index_sfinae = find_index_sfinae_impl<find_index<T, Ts...>()>;
template <std::size_t I>
struct find_index_checked_impl : lib::size_constant<I> {
static_assert(I != not_found, "the specified type is not found.");
static_assert(I != ambiguous, "the specified type is ambiguous.");
};
template <typename T, typename... Ts>
using find_index_checked = find_index_checked_impl<find_index<T, Ts...>()>;
struct valueless_t {};
enum class Trait { TriviallyAvailable, Available, Unavailable };
template <typename T,
template <typename> class IsTriviallyAvailable,
template <typename> class IsAvailable>
inline constexpr Trait trait() {
return IsTriviallyAvailable<T>::value
? Trait::TriviallyAvailable
: IsAvailable<T>::value ? Trait::Available
: Trait::Unavailable;
}
#ifdef MPARK_CPP14_CONSTEXPR
template <typename... Traits>
inline constexpr Trait common_trait(Traits... traits) {
Trait result = Trait::TriviallyAvailable;
for (Trait t : {traits...}) {
if (static_cast<int>(t) > static_cast<int>(result)) {
result = t;
}
}
return result;
}
#else
inline constexpr Trait common_trait_impl(Trait result) { return result; }
template <typename... Traits>
inline constexpr Trait common_trait_impl(Trait result,
Trait t,
Traits... ts) {
return static_cast<int>(t) > static_cast<int>(result)
? common_trait_impl(t, ts...)
: common_trait_impl(result, ts...);
}
template <typename... Traits>
inline constexpr Trait common_trait(Traits... ts) {
return common_trait_impl(Trait::TriviallyAvailable, ts...);
}
#endif
template <typename... Ts>
struct traits {
static constexpr Trait copy_constructible_trait =
common_trait(trait<Ts,
lib::is_trivially_copy_constructible,
std::is_copy_constructible>()...);
static constexpr Trait move_constructible_trait =
common_trait(trait<Ts,
lib::is_trivially_move_constructible,
std::is_move_constructible>()...);
static constexpr Trait copy_assignable_trait =
common_trait(copy_constructible_trait,
trait<Ts,
lib::is_trivially_copy_assignable,
std::is_copy_assignable>()...);
static constexpr Trait move_assignable_trait =
common_trait(move_constructible_trait,
trait<Ts,
lib::is_trivially_move_assignable,
std::is_move_assignable>()...);
static constexpr Trait destructible_trait =
common_trait(trait<Ts,
std::is_trivially_destructible,
std::is_destructible>()...);
};
namespace access {
struct recursive_union {
#ifdef MPARK_RETURN_TYPE_DEDUCTION
template <typename V>
inline static constexpr auto &&get_alt(V &&v, in_place_index_t<0>) {
return lib::forward<V>(v).head_;
}
template <typename V, std::size_t I>
inline static constexpr auto &&get_alt(V &&v, in_place_index_t<I>) {
return get_alt(lib::forward<V>(v).tail_, in_place_index_t<I - 1>{});
}
#else
template <std::size_t I, bool Dummy = true>
struct get_alt_impl {
template <typename V>
inline constexpr AUTO_REFREF operator()(V &&v) const
AUTO_REFREF_RETURN(get_alt_impl<I - 1>{}(lib::forward<V>(v).tail_))
};
template <bool Dummy>
struct get_alt_impl<0, Dummy> {
template <typename V>
inline constexpr AUTO_REFREF operator()(V &&v) const
AUTO_REFREF_RETURN(lib::forward<V>(v).head_)
};
template <typename V, std::size_t I>
inline static constexpr AUTO_REFREF get_alt(V &&v, in_place_index_t<I>)
AUTO_REFREF_RETURN(get_alt_impl<I>{}(lib::forward<V>(v)))
#endif
};
struct base {
template <std::size_t I, typename V>
inline static constexpr AUTO_REFREF get_alt(V &&v)
AUTO_REFREF_RETURN(recursive_union::get_alt(
data(lib::forward<V>(v)), in_place_index_t<I>{}))
};
struct variant {
template <std::size_t I, typename V>
inline static constexpr AUTO_REFREF get_alt(V &&v)
AUTO_REFREF_RETURN(base::get_alt<I>(lib::forward<V>(v).impl_))
};
} // namespace access
namespace visitation {
struct base {
private:
template <typename T>
inline static constexpr const T &at(const T &elem) {
return elem;
}
template <typename T, std::size_t N, typename... Is>
inline static constexpr const lib::remove_all_extents_t<T> &at(
const lib::array<T, N> &elems, std::size_t i, Is... is) {
return at(elems[i], is...);
}
template <typename F, typename... Fs>
inline static constexpr int visit_visitor_return_type_check() {
static_assert(all(std::is_same<F, Fs>::value...),
"`mpark::visit` requires the visitor to have a single "
"return type.");
return 0;
}
template <typename... Fs>
inline static constexpr lib::array<
lib::common_type_t<lib::decay_t<Fs>...>,
sizeof...(Fs)>
make_farray(Fs &&... fs) {
using result = lib::array<lib::common_type_t<lib::decay_t<Fs>...>,
sizeof...(Fs)>;
return visit_visitor_return_type_check<lib::decay_t<Fs>...>(),
result{{lib::forward<Fs>(fs)...}};
}
template <std::size_t... Is>
struct dispatcher {
template <typename F, typename... Vs>
struct impl {
inline static constexpr DECLTYPE_AUTO dispatch(F f, Vs... vs)
DECLTYPE_AUTO_RETURN(lib::invoke(
static_cast<F>(f),
access::base::get_alt<Is>(static_cast<Vs>(vs))...))
};
};
template <typename F, typename... Vs, std::size_t... Is>
inline static constexpr AUTO make_dispatch(lib::index_sequence<Is...>)
AUTO_RETURN(&dispatcher<Is...>::template impl<F, Vs...>::dispatch)
template <std::size_t I, typename F, typename... Vs>
inline static constexpr AUTO make_fdiagonal_impl()
AUTO_RETURN(make_dispatch<F, Vs...>(
lib::index_sequence<lib::indexed_type<I, Vs>::value...>{}))
template <typename F, typename... Vs, std::size_t... Is>
inline static constexpr AUTO make_fdiagonal_impl(
lib::index_sequence<Is...>)
AUTO_RETURN(make_farray(make_fdiagonal_impl<Is, F, Vs...>()...))
template <typename F, typename V, typename... Vs>
inline static constexpr /* auto * */ auto make_fdiagonal()
-> decltype(make_fdiagonal_impl<F, V, Vs...>(
lib::make_index_sequence<lib::decay_t<V>::size()>{})) {
static_assert(
all((lib::decay_t<V>::size() == lib::decay_t<Vs>::size())...),
"all of the variants must be the same size.");
return make_fdiagonal_impl<F, V, Vs...>(
lib::make_index_sequence<lib::decay_t<V>::size()>{});
}
#ifdef MPARK_RETURN_TYPE_DEDUCTION
template <typename F, typename... Vs, std::size_t... Is>
inline static constexpr auto make_fmatrix_impl(
lib::index_sequence<Is...> is) {
return make_dispatch<F, Vs...>(is);
}
template <typename F,
typename... Vs,
std::size_t... Is,
std::size_t... Js,
typename... Ls>
inline static constexpr auto make_fmatrix_impl(
lib::index_sequence<Is...>, lib::index_sequence<Js...>, Ls... ls) {
return make_farray(make_fmatrix_impl<F, Vs...>(
lib::index_sequence<Is..., Js>{}, ls...)...);
}
template <typename F, typename... Vs>
inline static constexpr auto make_fmatrix() {
return make_fmatrix_impl<F, Vs...>(
lib::index_sequence<>{},
lib::make_index_sequence<lib::decay_t<Vs>::size()>{}...);
}
#else
template <typename F, typename... Vs>
struct make_fmatrix_impl {
template <typename...>
struct impl;
template <std::size_t... Is>
struct impl<lib::index_sequence<Is...>> {
inline constexpr AUTO operator()() const
AUTO_RETURN(
make_dispatch<F, Vs...>(lib::index_sequence<Is...>{}))
};
template <std::size_t... Is, std::size_t... Js, typename... Ls>
struct impl<lib::index_sequence<Is...>,
lib::index_sequence<Js...>,
Ls...> {
inline constexpr AUTO operator()() const
AUTO_RETURN(make_farray(
impl<lib::index_sequence<Is..., Js>, Ls...>{}()...))
};
};
template <typename F, typename... Vs>
inline static constexpr AUTO make_fmatrix()
AUTO_RETURN(
typename make_fmatrix_impl<F, Vs...>::template impl<
lib::index_sequence<>,
lib::make_index_sequence<lib::decay_t<Vs>::size()>...>{}())
#endif
public:
template <typename Visitor, typename... Vs>
inline static constexpr DECLTYPE_AUTO visit_alt_at(std::size_t index,
Visitor &&visitor,
Vs &&... vs)
DECLTYPE_AUTO_RETURN(
at(make_fdiagonal<Visitor &&,
decltype(as_base(lib::forward<Vs>(vs)))...>(),
index)(lib::forward<Visitor>(visitor),
as_base(lib::forward<Vs>(vs))...))
template <typename Visitor, typename... Vs>
inline static constexpr DECLTYPE_AUTO visit_alt(Visitor &&visitor,
Vs &&... vs)
DECLTYPE_AUTO_RETURN(
at(make_fmatrix<Visitor &&,
decltype(as_base(lib::forward<Vs>(vs)))...>(),
vs.index()...)(lib::forward<Visitor>(visitor),
as_base(lib::forward<Vs>(vs))...))
};
struct variant {
private:
template <typename Visitor, typename... Values>
struct visit_exhaustive_visitor_check {
static_assert(
lib::is_invocable<Visitor, Values...>::value,
"`mpark::visit` requires the visitor to be exhaustive.");
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4100)
#endif
inline constexpr DECLTYPE_AUTO operator()(Visitor &&visitor,
Values &&... values) const
DECLTYPE_AUTO_RETURN(lib::invoke(lib::forward<Visitor>(visitor),
lib::forward<Values>(values)...))
#ifdef _MSC_VER
#pragma warning(pop)
#endif
};
template <typename Visitor>
struct value_visitor {
Visitor &&visitor_;
template <typename... Alts>
inline constexpr DECLTYPE_AUTO operator()(Alts &&... alts) const
DECLTYPE_AUTO_RETURN(
visit_exhaustive_visitor_check<
Visitor,
decltype((lib::forward<Alts>(alts).value))...>{}(
lib::forward<Visitor>(visitor_),
lib::forward<Alts>(alts).value...))
};
template <typename Visitor>
inline static constexpr AUTO make_value_visitor(Visitor &&visitor)
AUTO_RETURN(value_visitor<Visitor>{lib::forward<Visitor>(visitor)})
public:
template <typename Visitor, typename... Vs>
inline static constexpr DECLTYPE_AUTO visit_alt_at(std::size_t index,
Visitor &&visitor,
Vs &&... vs)
DECLTYPE_AUTO_RETURN(
base::visit_alt_at(index,
lib::forward<Visitor>(visitor),
lib::forward<Vs>(vs).impl_...))
template <typename Visitor, typename... Vs>
inline static constexpr DECLTYPE_AUTO visit_alt(Visitor &&visitor,
Vs &&... vs)
DECLTYPE_AUTO_RETURN(base::visit_alt(lib::forward<Visitor>(visitor),
lib::forward<Vs>(vs).impl_...))
template <typename Visitor, typename... Vs>
inline static constexpr DECLTYPE_AUTO visit_value_at(std::size_t index,
Visitor &&visitor,
Vs &&... vs)
DECLTYPE_AUTO_RETURN(
visit_alt_at(index,
make_value_visitor(lib::forward<Visitor>(visitor)),
lib::forward<Vs>(vs)...))
template <typename Visitor, typename... Vs>
inline static constexpr DECLTYPE_AUTO visit_value(Visitor &&visitor,
Vs &&... vs)
DECLTYPE_AUTO_RETURN(
visit_alt(make_value_visitor(lib::forward<Visitor>(visitor)),
lib::forward<Vs>(vs)...))
};
} // namespace visitation
template <std::size_t Index, typename T>
struct alt {
using value_type = T;
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4244)
#endif
template <typename... Args>
inline explicit constexpr alt(in_place_t, Args &&... args)
: value(lib::forward<Args>(args)...) {}
#ifdef _MSC_VER
#pragma warning(pop)
#endif
T value;
};
template <Trait DestructibleTrait, std::size_t Index, typename... Ts>
union recursive_union;
template <Trait DestructibleTrait, std::size_t Index>
union recursive_union<DestructibleTrait, Index> {};
#define MPARK_VARIANT_RECURSIVE_UNION(destructible_trait, destructor) \
template <std::size_t Index, typename T, typename... Ts> \
union recursive_union<destructible_trait, Index, T, Ts...> { \
public: \
inline explicit constexpr recursive_union(valueless_t) noexcept \
: dummy_{} {} \
\
template <typename... Args> \
inline explicit constexpr recursive_union(in_place_index_t<0>, \
Args &&... args) \
: head_(in_place_t{}, lib::forward<Args>(args)...) {} \
\
template <std::size_t I, typename... Args> \
inline explicit constexpr recursive_union(in_place_index_t<I>, \
Args &&... args) \
: tail_(in_place_index_t<I - 1>{}, lib::forward<Args>(args)...) {} \
\
recursive_union(const recursive_union &) = default; \
recursive_union(recursive_union &&) = default; \
\
destructor \
\
recursive_union &operator=(const recursive_union &) = default; \
recursive_union &operator=(recursive_union &&) = default; \
\
private: \
char dummy_; \
alt<Index, T> head_; \
recursive_union<destructible_trait, Index + 1, Ts...> tail_; \
\
friend struct access::recursive_union; \
}
MPARK_VARIANT_RECURSIVE_UNION(Trait::TriviallyAvailable,
~recursive_union() = default;);
MPARK_VARIANT_RECURSIVE_UNION(Trait::Available,
~recursive_union() {});
MPARK_VARIANT_RECURSIVE_UNION(Trait::Unavailable,
~recursive_union() = delete;);
#undef MPARK_VARIANT_RECURSIVE_UNION
using index_t = unsigned int;
template <Trait DestructibleTrait, typename... Ts>
class base {
public:
inline explicit constexpr base(valueless_t tag) noexcept
: data_(tag), index_(static_cast<index_t>(-1)) {}
template <std::size_t I, typename... Args>
inline explicit constexpr base(in_place_index_t<I>, Args &&... args)
: data_(in_place_index_t<I>{}, lib::forward<Args>(args)...),
index_(I) {}
inline constexpr bool valueless_by_exception() const noexcept {
return index_ == static_cast<index_t>(-1);
}
inline constexpr std::size_t index() const noexcept {
return valueless_by_exception() ? variant_npos : index_;
}
protected:
using data_t = recursive_union<DestructibleTrait, 0, Ts...>;
friend inline constexpr base &as_base(base &b) { return b; }
friend inline constexpr const base &as_base(const base &b) { return b; }
friend inline constexpr base &&as_base(base &&b) { return lib::move(b); }
friend inline constexpr const base &&as_base(const base &&b) { return lib::move(b); }
friend inline constexpr data_t &data(base &b) { return b.data_; }
friend inline constexpr const data_t &data(const base &b) { return b.data_; }
friend inline constexpr data_t &&data(base &&b) { return lib::move(b).data_; }
friend inline constexpr const data_t &&data(const base &&b) { return lib::move(b).data_; }
inline static constexpr std::size_t size() { return sizeof...(Ts); }
data_t data_;
index_t index_;
friend struct access::base;
friend struct visitation::base;
};
struct dtor {
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4100)
#endif
template <typename Alt>
inline void operator()(Alt &alt) const noexcept { alt.~Alt(); }
#ifdef _MSC_VER
#pragma warning(pop)
#endif
};
#if defined(_MSC_VER) && _MSC_VER < 1910
#define INHERITING_CTOR(type, base) \
template <typename... Args> \
inline explicit constexpr type(Args &&... args) \
: base(lib::forward<Args>(args)...) {}
#else
#define INHERITING_CTOR(type, base) using base::base;
#endif
template <typename Traits, Trait = Traits::destructible_trait>
class destructor;
#define MPARK_VARIANT_DESTRUCTOR(destructible_trait, definition, destroy) \
template <typename... Ts> \
class destructor<traits<Ts...>, destructible_trait> \
: public base<destructible_trait, Ts...> { \
using super = base<destructible_trait, Ts...>; \
\
public: \
INHERITING_CTOR(destructor, super) \
using super::operator=; \
\
destructor(const destructor &) = default; \
destructor(destructor &&) = default; \
definition \
destructor &operator=(const destructor &) = default; \
destructor &operator=(destructor &&) = default; \
\
protected: \
destroy \
}
MPARK_VARIANT_DESTRUCTOR(
Trait::TriviallyAvailable,
~destructor() = default;,
inline void destroy() noexcept {
this->index_ = static_cast<index_t>(-1);
});
MPARK_VARIANT_DESTRUCTOR(
Trait::Available,
~destructor() { destroy(); },
inline void destroy() noexcept {
if (!this->valueless_by_exception()) {
visitation::base::visit_alt(dtor{}, *this);
}
this->index_ = static_cast<index_t>(-1);
});
MPARK_VARIANT_DESTRUCTOR(
Trait::Unavailable,
~destructor() = delete;,
inline void destroy() noexcept = delete;);
#undef MPARK_VARIANT_DESTRUCTOR
template <typename Traits>
class constructor : public destructor<Traits> {
using super = destructor<Traits>;
public:
INHERITING_CTOR(constructor, super)
using super::operator=;
protected:
#ifndef MPARK_GENERIC_LAMBDAS
struct ctor {
template <typename LhsAlt, typename RhsAlt>
inline void operator()(LhsAlt &lhs_alt, RhsAlt &&rhs_alt) const {
constructor::construct_alt(lhs_alt,
lib::forward<RhsAlt>(rhs_alt).value);
}
};
#endif
template <std::size_t I, typename T, typename... Args>
inline static T &construct_alt(alt<I, T> &a, Args &&... args) {
::new (static_cast<void *>(lib::addressof(a)))
alt<I, T>(in_place_t{}, lib::forward<Args>(args)...);
return a.value;
}
template <typename Rhs>
inline static void generic_construct(constructor &lhs, Rhs &&rhs) {
lhs.destroy();
if (!rhs.valueless_by_exception()) {
visitation::base::visit_alt_at(
rhs.index(),
#ifdef MPARK_GENERIC_LAMBDAS
[](auto &lhs_alt, auto &&rhs_alt) {
constructor::construct_alt(
lhs_alt, lib::forward<decltype(rhs_alt)>(rhs_alt).value);
}
#else
ctor{}
#endif
,
lhs,
lib::forward<Rhs>(rhs));
lhs.index_ = rhs.index_;
}
}
};
template <typename Traits, Trait = Traits::move_constructible_trait>
class move_constructor;
#define MPARK_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, definition) \
template <typename... Ts> \
class move_constructor<traits<Ts...>, move_constructible_trait> \
: public constructor<traits<Ts...>> { \
using super = constructor<traits<Ts...>>; \
\
public: \
INHERITING_CTOR(move_constructor, super) \
using super::operator=; \
\
move_constructor(const move_constructor &) = default; \
definition \
~move_constructor() = default; \
move_constructor &operator=(const move_constructor &) = default; \
move_constructor &operator=(move_constructor &&) = default; \
}
MPARK_VARIANT_MOVE_CONSTRUCTOR(
Trait::TriviallyAvailable,
move_constructor(move_constructor &&that) = default;);
MPARK_VARIANT_MOVE_CONSTRUCTOR(
Trait::Available,
move_constructor(move_constructor &&that) noexcept(
all(std::is_nothrow_move_constructible<Ts>::value...))
: move_constructor(valueless_t{}) {
this->generic_construct(*this, lib::move(that));
});
MPARK_VARIANT_MOVE_CONSTRUCTOR(
Trait::Unavailable,
move_constructor(move_constructor &&) = delete;);
#undef MPARK_VARIANT_MOVE_CONSTRUCTOR
template <typename Traits, Trait = Traits::copy_constructible_trait>
class copy_constructor;
#define MPARK_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, definition) \
template <typename... Ts> \
class copy_constructor<traits<Ts...>, copy_constructible_trait> \
: public move_constructor<traits<Ts...>> { \
using super = move_constructor<traits<Ts...>>; \
\
public: \
INHERITING_CTOR(copy_constructor, super) \
using super::operator=; \
\
definition \
copy_constructor(copy_constructor &&) = default; \
~copy_constructor() = default; \
copy_constructor &operator=(const copy_constructor &) = default; \
copy_constructor &operator=(copy_constructor &&) = default; \
}
MPARK_VARIANT_COPY_CONSTRUCTOR(
Trait::TriviallyAvailable,
copy_constructor(const copy_constructor &that) = default;);
MPARK_VARIANT_COPY_CONSTRUCTOR(
Trait::Available,
copy_constructor(const copy_constructor &that)
: copy_constructor(valueless_t{}) {
this->generic_construct(*this, that);
});
MPARK_VARIANT_COPY_CONSTRUCTOR(
Trait::Unavailable,
copy_constructor(const copy_constructor &) = delete;);
#undef MPARK_VARIANT_COPY_CONSTRUCTOR
template <typename Traits>
class assignment : public copy_constructor<Traits> {
using super = copy_constructor<Traits>;
public:
INHERITING_CTOR(assignment, super)
using super::operator=;
template <std::size_t I, typename... Args>
inline /* auto & */ auto emplace(Args &&... args)
-> decltype(this->construct_alt(access::base::get_alt<I>(*this),
lib::forward<Args>(args)...)) {
this->destroy();
auto &result = this->construct_alt(access::base::get_alt<I>(*this),
lib::forward<Args>(args)...);
this->index_ = I;
return result;
}
protected:
#ifndef MPARK_GENERIC_LAMBDAS
template <typename That>
struct assigner {
template <typename ThisAlt, typename ThatAlt>
inline void operator()(ThisAlt &this_alt, ThatAlt &&that_alt) const {
self->assign_alt(this_alt, lib::forward<ThatAlt>(that_alt).value);
}
assignment *self;
};
#endif
template <std::size_t I, typename T, typename Arg>
inline void assign_alt(alt<I, T> &a, Arg &&arg) {
if (this->index() == I) {
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4244)
#endif
a.value = lib::forward<Arg>(arg);
#ifdef _MSC_VER
#pragma warning(pop)
#endif
} else {
struct {
void operator()(std::true_type) const {
this_->emplace<I>(lib::forward<Arg>(arg_));
}
void operator()(std::false_type) const {
this_->emplace<I>(T(lib::forward<Arg>(arg_)));
}
assignment *this_;
Arg &&arg_;
} impl{this, lib::forward<Arg>(arg)};
impl(lib::bool_constant<
std::is_nothrow_constructible<T, Arg>::value ||
!std::is_nothrow_move_constructible<T>::value>{});
}
}
template <typename That>
inline void generic_assign(That &&that) {
if (this->valueless_by_exception() && that.valueless_by_exception()) {
// do nothing.
} else if (that.valueless_by_exception()) {
this->destroy();
} else {
visitation::base::visit_alt_at(
that.index(),
#ifdef MPARK_GENERIC_LAMBDAS
[this](auto &this_alt, auto &&that_alt) {
this->assign_alt(
this_alt, lib::forward<decltype(that_alt)>(that_alt).value);
}
#else
assigner<That>{this}
#endif
,
*this,
lib::forward<That>(that));
}
}
};
template <typename Traits, Trait = Traits::move_assignable_trait>
class move_assignment;
#define MPARK_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, definition) \
template <typename... Ts> \
class move_assignment<traits<Ts...>, move_assignable_trait> \
: public assignment<traits<Ts...>> { \
using super = assignment<traits<Ts...>>; \
\
public: \
INHERITING_CTOR(move_assignment, super) \
using super::operator=; \
\
move_assignment(const move_assignment &) = default; \
move_assignment(move_assignment &&) = default; \
~move_assignment() = default; \
move_assignment &operator=(const move_assignment &) = default; \
definition \
}
MPARK_VARIANT_MOVE_ASSIGNMENT(
Trait::TriviallyAvailable,
move_assignment &operator=(move_assignment &&that) = default;);
MPARK_VARIANT_MOVE_ASSIGNMENT(
Trait::Available,
move_assignment &
operator=(move_assignment &&that) noexcept(
all((std::is_nothrow_move_constructible<Ts>::value &&
std::is_nothrow_move_assignable<Ts>::value)...)) {
this->generic_assign(lib::move(that));
return *this;
});
MPARK_VARIANT_MOVE_ASSIGNMENT(
Trait::Unavailable,
move_assignment &operator=(move_assignment &&) = delete;);
#undef MPARK_VARIANT_MOVE_ASSIGNMENT
template <typename Traits, Trait = Traits::copy_assignable_trait>
class copy_assignment;
#define MPARK_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, definition) \
template <typename... Ts> \
class copy_assignment<traits<Ts...>, copy_assignable_trait> \
: public move_assignment<traits<Ts...>> { \
using super = move_assignment<traits<Ts...>>; \
\
public: \
INHERITING_CTOR(copy_assignment, super) \
using super::operator=; \
\
copy_assignment(const copy_assignment &) = default; \
copy_assignment(copy_assignment &&) = default; \
~copy_assignment() = default; \
definition \
copy_assignment &operator=(copy_assignment &&) = default; \
}
MPARK_VARIANT_COPY_ASSIGNMENT(
Trait::TriviallyAvailable,
copy_assignment &operator=(const copy_assignment &that) = default;);
MPARK_VARIANT_COPY_ASSIGNMENT(
Trait::Available,
copy_assignment &operator=(const copy_assignment &that) {
this->generic_assign(that);
return *this;
});
MPARK_VARIANT_COPY_ASSIGNMENT(
Trait::Unavailable,
copy_assignment &operator=(const copy_assignment &) = delete;);
#undef MPARK_VARIANT_COPY_ASSIGNMENT
template <typename... Ts>
class impl : public copy_assignment<traits<Ts...>> {
using super = copy_assignment<traits<Ts...>>;
public:
INHERITING_CTOR(impl, super)
using super::operator=;
template <std::size_t I, typename Arg>
inline void assign(Arg &&arg) {
this->assign_alt(access::base::get_alt<I>(*this),
lib::forward<Arg>(arg));
}
inline void swap(impl &that) {
if (this->valueless_by_exception() && that.valueless_by_exception()) {
// do nothing.
} else if (this->index() == that.index()) {
visitation::base::visit_alt_at(this->index(),
#ifdef MPARK_GENERIC_LAMBDAS
[](auto &this_alt, auto &that_alt) {
using std::swap;
swap(this_alt.value,
that_alt.value);
}
#else
swapper{}
#endif
,
*this,
that);
} else {
impl *lhs = this;
impl *rhs = lib::addressof(that);
if (lhs->move_nothrow() && !rhs->move_nothrow()) {
std::swap(lhs, rhs);
}
impl tmp(lib::move(*rhs));
#ifdef MPARK_EXCEPTIONS
// EXTENSION: When the move construction of `lhs` into `rhs` throws
// and `tmp` is nothrow move constructible then we move `tmp` back
// into `rhs` and provide the strong exception safety guarantee.
try {
this->generic_construct(*rhs, lib::move(*lhs));
} catch (...) {
if (tmp.move_nothrow()) {
this->generic_construct(*rhs, lib::move(tmp));
}
throw;
}
#else
this->generic_construct(*rhs, lib::move(*lhs));
#endif
this->generic_construct(*lhs, lib::move(tmp));
}
}
private:
#ifndef MPARK_GENERIC_LAMBDAS
struct swapper {
template <typename ThisAlt, typename ThatAlt>
inline void operator()(ThisAlt &this_alt, ThatAlt &that_alt) const {
using std::swap;
swap(this_alt.value, that_alt.value);
}
};
#endif
inline constexpr bool move_nothrow() const {
return this->valueless_by_exception() ||
lib::array<bool, sizeof...(Ts)>{
{std::is_nothrow_move_constructible<Ts>::value...}
}[this->index()];
}
};
template <typename... Ts>
struct overload;
template <>
struct overload<> { void operator()() const {} };
template <typename T, typename... Ts>
struct overload<T, Ts...> : overload<Ts...> {
using overload<Ts...>::operator();
lib::identity<T> operator()(T) const { return {}; }
};
template <typename T, typename... Ts>
using best_match_t =
typename lib::invoke_result_t<overload<Ts...>, T &&>::type;
template <typename T>
struct is_in_place_index : std::false_type {};
template <std::size_t I>
struct is_in_place_index<in_place_index_t<I>> : std::true_type {};
template <typename T>
struct is_in_place_type : std::false_type {};
template <typename T>
struct is_in_place_type<in_place_type_t<T>> : std::true_type {};
} // detail
template <typename... Ts>
class variant {
static_assert(0 < sizeof...(Ts),
"variant must consist of at least one alternative.");
static_assert(lib::all<!std::is_array<Ts>::value...>::value,
"variant can not have an array type as an alternative.");
static_assert(lib::all<!std::is_reference<Ts>::value...>::value,
"variant can not have a reference type as an alternative.");
static_assert(lib::all<!std::is_void<Ts>::value...>::value,
"variant can not have a void type as an alternative.");
public:
template <
typename Front = lib::type_pack_element_t<0, Ts...>,
lib::enable_if_t<std::is_default_constructible<Front>::value, int> = 0>
inline constexpr variant() noexcept(
std::is_nothrow_default_constructible<Front>::value)
: impl_(in_place_index_t<0>{}) {}
variant(const variant &) = default;
variant(variant &&) = default;
template <
typename Arg,
typename Decayed = lib::decay_t<Arg>,
lib::enable_if_t<!std::is_same<Decayed, variant>::value, int> = 0,
lib::enable_if_t<!detail::is_in_place_index<Decayed>::value, int> = 0,
lib::enable_if_t<!detail::is_in_place_type<Decayed>::value, int> = 0,
typename T = detail::best_match_t<Arg, Ts...>,
std::size_t I = detail::find_index_sfinae<T, Ts...>::value,
lib::enable_if_t<std::is_constructible<T, Arg>::value, int> = 0>
inline constexpr variant(Arg &&arg) noexcept(
std::is_nothrow_constructible<T, Arg>::value)
: impl_(in_place_index_t<I>{}, lib::forward<Arg>(arg)) {}
template <
std::size_t I,
typename... Args,
typename T = lib::type_pack_element_t<I, Ts...>,
lib::enable_if_t<std::is_constructible<T, Args...>::value, int> = 0>
inline explicit constexpr variant(
in_place_index_t<I>,
Args &&... args) noexcept(std::is_nothrow_constructible<T,
Args...>::value)
: impl_(in_place_index_t<I>{}, lib::forward<Args>(args)...) {}
template <
std::size_t I,
typename Up,
typename... Args,
typename T = lib::type_pack_element_t<I, Ts...>,
lib::enable_if_t<std::is_constructible<T,
std::initializer_list<Up> &,
Args...>::value,
int> = 0>
inline explicit constexpr variant(
in_place_index_t<I>,
std::initializer_list<Up> il,
Args &&... args) noexcept(std::
is_nothrow_constructible<
T,
std::initializer_list<Up> &,
Args...>::value)
: impl_(in_place_index_t<I>{}, il, lib::forward<Args>(args)...) {}
template <
typename T,
typename... Args,
std::size_t I = detail::find_index_sfinae<T, Ts...>::value,
lib::enable_if_t<std::is_constructible<T, Args...>::value, int> = 0>
inline explicit constexpr variant(
in_place_type_t<T>,
Args &&... args) noexcept(std::is_nothrow_constructible<T,
Args...>::value)
: impl_(in_place_index_t<I>{}, lib::forward<Args>(args)...) {}
template <
typename T,
typename Up,
typename... Args,
std::size_t I = detail::find_index_sfinae<T, Ts...>::value,
lib::enable_if_t<std::is_constructible<T,
std::initializer_list<Up> &,
Args...>::value,
int> = 0>
inline explicit constexpr variant(
in_place_type_t<T>,
std::initializer_list<Up> il,
Args &&... args) noexcept(std::
is_nothrow_constructible<
T,
std::initializer_list<Up> &,
Args...>::value)
: impl_(in_place_index_t<I>{}, il, lib::forward<Args>(args)...) {}
~variant() = default;
variant &operator=(const variant &) = default;
variant &operator=(variant &&) = default;
template <typename Arg,
lib::enable_if_t<!std::is_same<lib::decay_t<Arg>, variant>::value,
int> = 0,
typename T = detail::best_match_t<Arg, Ts...>,
std::size_t I = detail::find_index_sfinae<T, Ts...>::value,
lib::enable_if_t<(std::is_assignable<T &, Arg>::value &&
std::is_constructible<T, Arg>::value),
int> = 0>
inline variant &operator=(Arg &&arg) noexcept(
(std::is_nothrow_assignable<T &, Arg>::value &&
std::is_nothrow_constructible<T, Arg>::value)) {
impl_.template assign<I>(lib::forward<Arg>(arg));
return *this;
}
template <
std::size_t I,
typename... Args,
typename T = lib::type_pack_element_t<I, Ts...>,
lib::enable_if_t<std::is_constructible<T, Args...>::value, int> = 0>
inline T &emplace(Args &&... args) {
return impl_.template emplace<I>(lib::forward<Args>(args)...);
}
template <
std::size_t I,
typename Up,
typename... Args,
typename T = lib::type_pack_element_t<I, Ts...>,
lib::enable_if_t<std::is_constructible<T,
std::initializer_list<Up> &,
Args...>::value,
int> = 0>
inline T &emplace(std::initializer_list<Up> il, Args &&... args) {
return impl_.template emplace<I>(il, lib::forward<Args>(args)...);
}
template <
typename T,
typename... Args,
std::size_t I = detail::find_index_sfinae<T, Ts...>::value,
lib::enable_if_t<std::is_constructible<T, Args...>::value, int> = 0>
inline T &emplace(Args &&... args) {
return impl_.template emplace<I>(lib::forward<Args>(args)...);
}
template <
typename T,
typename Up,
typename... Args,
std::size_t I = detail::find_index_sfinae<T, Ts...>::value,
lib::enable_if_t<std::is_constructible<T,
std::initializer_list<Up> &,
Args...>::value,
int> = 0>
inline T &emplace(std::initializer_list<Up> il, Args &&... args) {
return impl_.template emplace<I>(il, lib::forward<Args>(args)...);
}
inline constexpr bool valueless_by_exception() const noexcept {
return impl_.valueless_by_exception();
}
inline constexpr std::size_t index() const noexcept {
return impl_.index();
}
template <
bool Dummy = true,
lib::enable_if_t<lib::all<Dummy,
(std::is_move_constructible<Ts>::value &&
lib::is_swappable<Ts>::value)...>::value,
int> = 0>
inline void swap(variant &that) noexcept(
lib::all<(std::is_nothrow_move_constructible<Ts>::value &&
lib::is_nothrow_swappable<Ts>::value)...>::value) {
impl_.swap(that.impl_);
}
private:
detail::impl<Ts...> impl_;
friend struct detail::access::variant;
friend struct detail::visitation::variant;
};
template <std::size_t I, typename... Ts>
inline constexpr bool holds_alternative(const variant<Ts...> &v) noexcept {
return v.index() == I;
}
template <typename T, typename... Ts>
inline constexpr bool holds_alternative(const variant<Ts...> &v) noexcept {
return holds_alternative<detail::find_index_checked<T, Ts...>::value>(v);
}
namespace detail {
template <std::size_t I, typename V>
struct generic_get_impl {
constexpr generic_get_impl(int) {}
constexpr AUTO_REFREF operator()(V &&v) const
AUTO_REFREF_RETURN(
access::variant::get_alt<I>(lib::forward<V>(v)).value)
};
template <std::size_t I, typename V>
inline constexpr AUTO_REFREF generic_get(V &&v)
AUTO_REFREF_RETURN(generic_get_impl<I, V>(
holds_alternative<I>(v) ? 0 : (throw_bad_variant_access(), 0))(
lib::forward<V>(v)))
} // namespace detail
template <std::size_t I, typename... Ts>
inline constexpr variant_alternative_t<I, variant<Ts...>> &get(
variant<Ts...> &v) {
return detail::generic_get<I>(v);
}
template <std::size_t I, typename... Ts>
inline constexpr variant_alternative_t<I, variant<Ts...>> &&get(
variant<Ts...> &&v) {
return detail::generic_get<I>(lib::move(v));
}
template <std::size_t I, typename... Ts>
inline constexpr const variant_alternative_t<I, variant<Ts...>> &get(
const variant<Ts...> &v) {
return detail::generic_get<I>(v);
}
template <std::size_t I, typename... Ts>
inline constexpr const variant_alternative_t<I, variant<Ts...>> &&get(
const variant<Ts...> &&v) {
return detail::generic_get<I>(lib::move(v));
}
template <typename T, typename... Ts>
inline constexpr T &get(variant<Ts...> &v) {
return get<detail::find_index_checked<T, Ts...>::value>(v);
}
template <typename T, typename... Ts>
inline constexpr T &&get(variant<Ts...> &&v) {
return get<detail::find_index_checked<T, Ts...>::value>(lib::move(v));
}
template <typename T, typename... Ts>
inline constexpr const T &get(const variant<Ts...> &v) {
return get<detail::find_index_checked<T, Ts...>::value>(v);
}
template <typename T, typename... Ts>
inline constexpr const T &&get(const variant<Ts...> &&v) {
return get<detail::find_index_checked<T, Ts...>::value>(lib::move(v));
}
namespace detail {
template <std::size_t I, typename V>
inline constexpr /* auto * */ AUTO generic_get_if(V *v) noexcept
AUTO_RETURN(v && holds_alternative<I>(*v)
? lib::addressof(access::variant::get_alt<I>(*v).value)
: nullptr)
} // namespace detail
template <std::size_t I, typename... Ts>
inline constexpr lib::add_pointer_t<variant_alternative_t<I, variant<Ts...>>>
get_if(variant<Ts...> *v) noexcept {
return detail::generic_get_if<I>(v);
}
template <std::size_t I, typename... Ts>
inline constexpr lib::add_pointer_t<
const variant_alternative_t<I, variant<Ts...>>>
get_if(const variant<Ts...> *v) noexcept {
return detail::generic_get_if<I>(v);
}
template <typename T, typename... Ts>
inline constexpr lib::add_pointer_t<T>
get_if(variant<Ts...> *v) noexcept {
return get_if<detail::find_index_checked<T, Ts...>::value>(v);
}
template <typename T, typename... Ts>
inline constexpr lib::add_pointer_t<const T>
get_if(const variant<Ts...> *v) noexcept {
return get_if<detail::find_index_checked<T, Ts...>::value>(v);
}
template <typename... Ts>
inline constexpr bool operator==(const variant<Ts...> &lhs,
const variant<Ts...> &rhs) {
using detail::visitation::variant;
using lib::equal_to;
#ifdef MPARK_CPP14_CONSTEXPR
if (lhs.index() != rhs.index()) return false;
if (lhs.valueless_by_exception()) return true;
return variant::visit_value_at(lhs.index(), equal_to{}, lhs, rhs);
#else
return lhs.index() == rhs.index() &&
(lhs.valueless_by_exception() ||
variant::visit_value_at(lhs.index(), equal_to{}, lhs, rhs));
#endif
}
template <typename... Ts>
inline constexpr bool operator!=(const variant<Ts...> &lhs,
const variant<Ts...> &rhs) {
using detail::visitation::variant;
using lib::not_equal_to;
#ifdef MPARK_CPP14_CONSTEXPR
if (lhs.index() != rhs.index()) return true;
if (lhs.valueless_by_exception()) return false;
return variant::visit_value_at(lhs.index(), not_equal_to{}, lhs, rhs);
#else
return lhs.index() != rhs.index() ||
(!lhs.valueless_by_exception() &&
variant::visit_value_at(lhs.index(), not_equal_to{}, lhs, rhs));
#endif
}
template <typename... Ts>
inline constexpr bool operator<(const variant<Ts...> &lhs,
const variant<Ts...> &rhs) {
using detail::visitation::variant;
using lib::less;
#ifdef MPARK_CPP14_CONSTEXPR
if (rhs.valueless_by_exception()) return false;
if (lhs.valueless_by_exception()) return true;
if (lhs.index() < rhs.index()) return true;
if (lhs.index() > rhs.index()) return false;
return variant::visit_value_at(lhs.index(), less{}, lhs, rhs);
#else
return !rhs.valueless_by_exception() &&
(lhs.valueless_by_exception() || lhs.index() < rhs.index() ||
(lhs.index() == rhs.index() &&
variant::visit_value_at(lhs.index(), less{}, lhs, rhs)));
#endif
}
template <typename... Ts>
inline constexpr bool operator>(const variant<Ts...> &lhs,
const variant<Ts...> &rhs) {
using detail::visitation::variant;
using lib::greater;
#ifdef MPARK_CPP14_CONSTEXPR
if (lhs.valueless_by_exception()) return false;
if (rhs.valueless_by_exception()) return true;
if (lhs.index() > rhs.index()) return true;
if (lhs.index() < rhs.index()) return false;
return variant::visit_value_at(lhs.index(), greater{}, lhs, rhs);
#else
return !lhs.valueless_by_exception() &&
(rhs.valueless_by_exception() || lhs.index() > rhs.index() ||
(lhs.index() == rhs.index() &&
variant::visit_value_at(lhs.index(), greater{}, lhs, rhs)));
#endif
}
template <typename... Ts>
inline constexpr bool operator<=(const variant<Ts...> &lhs,
const variant<Ts...> &rhs) {
using detail::visitation::variant;
using lib::less_equal;
#ifdef MPARK_CPP14_CONSTEXPR
if (lhs.valueless_by_exception()) return true;
if (rhs.valueless_by_exception()) return false;
if (lhs.index() < rhs.index()) return true;
if (lhs.index() > rhs.index()) return false;
return variant::visit_value_at(lhs.index(), less_equal{}, lhs, rhs);
#else
return lhs.valueless_by_exception() ||
(!rhs.valueless_by_exception() &&
(lhs.index() < rhs.index() ||
(lhs.index() == rhs.index() &&
variant::visit_value_at(lhs.index(), less_equal{}, lhs, rhs))));
#endif
}
template <typename... Ts>
inline constexpr bool operator>=(const variant<Ts...> &lhs,
const variant<Ts...> &rhs) {
using detail::visitation::variant;
using lib::greater_equal;
#ifdef MPARK_CPP14_CONSTEXPR
if (rhs.valueless_by_exception()) return true;
if (lhs.valueless_by_exception()) return false;
if (lhs.index() > rhs.index()) return true;
if (lhs.index() < rhs.index()) return false;
return variant::visit_value_at(lhs.index(), greater_equal{}, lhs, rhs);
#else
return rhs.valueless_by_exception() ||
(!lhs.valueless_by_exception() &&
(lhs.index() > rhs.index() ||
(lhs.index() == rhs.index() &&
variant::visit_value_at(
lhs.index(), greater_equal{}, lhs, rhs))));
#endif
}
template <typename Visitor, typename... Vs>
inline constexpr DECLTYPE_AUTO visit(Visitor &&visitor, Vs &&... vs)
DECLTYPE_AUTO_RETURN(
(detail::all(!vs.valueless_by_exception()...)
? (void)0
: throw_bad_variant_access()),
detail::visitation::variant::visit_value(lib::forward<Visitor>(visitor),
lib::forward<Vs>(vs)...))
struct monostate {};
inline constexpr bool operator<(monostate, monostate) noexcept {
return false;
}
inline constexpr bool operator>(monostate, monostate) noexcept {
return false;
}
inline constexpr bool operator<=(monostate, monostate) noexcept {
return true;
}
inline constexpr bool operator>=(monostate, monostate) noexcept {
return true;
}
inline constexpr bool operator==(monostate, monostate) noexcept {
return true;
}
inline constexpr bool operator!=(monostate, monostate) noexcept {
return false;
}
template <typename... Ts>
inline auto swap(variant<Ts...> &lhs,
variant<Ts...> &rhs) noexcept(noexcept(lhs.swap(rhs)))
-> decltype(lhs.swap(rhs)) {
lhs.swap(rhs);
}
namespace detail {
template <typename T, typename...>
using enabled_type = T;
namespace hash {
template <typename H, typename K>
constexpr bool meets_requirements() {
return std::is_copy_constructible<H>::value &&
std::is_move_constructible<H>::value &&
lib::is_invocable_r<std::size_t, H, const K &>::value;
}
template <typename K>
constexpr bool is_enabled() {
using H = std::hash<K>;
return meets_requirements<H, K>() &&
std::is_default_constructible<H>::value &&
std::is_copy_assignable<H>::value &&
std::is_move_assignable<H>::value;
}
} // namespace hash
} // namespace detail
#undef AUTO
#undef AUTO_RETURN
#undef AUTO_REFREF
#undef AUTO_REFREF_RETURN
#undef DECLTYPE_AUTO
#undef DECLTYPE_AUTO_RETURN
} // namespace mpark
namespace std {
template <typename... Ts>
struct hash<mpark::detail::enabled_type<
mpark::variant<Ts...>,
mpark::lib::enable_if_t<mpark::lib::all<mpark::detail::hash::is_enabled<
mpark::lib::remove_const_t<Ts>>()...>::value>>> {
using argument_type = mpark::variant<Ts...>;
using result_type = std::size_t;
inline result_type operator()(const argument_type &v) const {
using mpark::detail::visitation::variant;
std::size_t result =
v.valueless_by_exception()
? 299792458 // Random value chosen by the universe upon creation
: variant::visit_alt(
#ifdef MPARK_GENERIC_LAMBDAS
[](const auto &alt) {
using alt_type = mpark::lib::decay_t<decltype(alt)>;
using value_type = mpark::lib::remove_const_t<
typename alt_type::value_type>;
return hash<value_type>{}(alt.value);
}
#else
hasher{}
#endif
,
v);
return hash_combine(result, hash<std::size_t>{}(v.index()));
}
private:
#ifndef MPARK_GENERIC_LAMBDAS
struct hasher {
template <typename Alt>
inline std::size_t operator()(const Alt &alt) const {
using alt_type = mpark::lib::decay_t<Alt>;
using value_type =
mpark::lib::remove_const_t<typename alt_type::value_type>;
return hash<value_type>{}(alt.value);
}
};
#endif
static std::size_t hash_combine(std::size_t lhs, std::size_t rhs) {
return lhs ^= rhs + 0x9e3779b9 + (lhs << 6) + (lhs >> 2);
}
};
template <>
struct hash<mpark::monostate> {
using argument_type = mpark::monostate;
using result_type = std::size_t;
inline result_type operator()(const argument_type &) const noexcept {
return 66740831; // return a fundamentally attractive random value.
}
};
} // namespace std
#endif // MPARK_VARIANT_HPP
