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dolphin/Source/Core/Common/Compat/variant
Léo Lam e38a66fe1b Common: Add a std::variant implementation 
Based on https://github.com/mpark/variant (which is based on libc++).
2017-06-03 12:36:24 +02:00

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// Copyright 2017 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.
#pragma once
#if __has_include_next(<variant>)
#include_next <variant>
#else
// 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)
/*
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(::std::in_place_type_t<T>, Args&&...);
template <class T, class U, class... Args>
constexpr explicit variant(
::std::in_place_type_t<T>, initializer_list<U>, Args&&...);
template <size_t I, class... Args>
constexpr explicit variant(::std::in_place_index_t<I>, Args&&...);
template <size_t I, class U, class... Args>
constexpr explicit variant(
::std::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 "in_place.h"
// 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_CONFIG_HPP
#define MPARK_CONFIG_HPP
// MSVC 2015 Update 3.
#if __cplusplus < 201103L && (!defined(_MSC_VER) || _MSC_FULL_VER < 190024215)
#error "MPark.Variant requires C++11 support."
#endif
#ifndef __has_builtin
#define __has_builtin(x) 0
#endif
#ifndef __has_feature
#define __has_feature(x) 0
#endif
#if __has_builtin(__builtin_addressof) || __GNUC__ >= 7 || defined(_MSC_VER)
#define MPARK_BUILTIN_ADDRESSOF
#endif
#if __has_builtin(__type_pack_element)
#define MPARK_TYPE_PACK_ELEMENT
#endif
#if defined(__cpp_constexpr) && __cpp_constexpr >= 201304
#define MPARK_CPP14_CONSTEXPR
#endif
#if __has_feature(cxx_exceptions) || defined(__cpp_exceptions)
#define MPARK_EXCEPTIONS
#endif
#if defined(__cpp_generic_lambdas) || defined(_MSC_VER)
#define MPARK_GENERIC_LAMBDAS
#endif
#if defined(__cpp_lib_integer_sequence)
#define MPARK_INTEGER_SEQUENCE
#endif
#if defined(__cpp_return_type_deduction) || defined(_MSC_VER)
#define MPARK_RETURN_TYPE_DEDUCTION
#endif
#if defined(__cpp_lib_transparent_operators) || defined(_MSC_VER)
#define MPARK_TRANSPARENT_OPERATORS
#endif
#if defined(__cpp_variable_templates) || defined(_MSC_VER)
#define MPARK_VARIABLE_TEMPLATES
#endif
#endif // MPARK_CONFIG_HPP
// 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_LIB_HPP
#define MPARK_LIB_HPP
#include <functional>
#include <memory>
#include <type_traits>
#include <utility>
#define RETURN(...) \
noexcept(noexcept(__VA_ARGS__))->decltype(__VA_ARGS__) { return __VA_ARGS__; }
namespace mpark
{
namespace lib
{
template <typename T>
struct identity
{
using type = T;
};
inline namespace cpp14
{
template <typename T, std::size_t N>
struct array
{
constexpr const T& operator[](std::size_t index) const { return data[index]; }
T data[N == 0 ? 1 : N];
};
template <typename T>
using add_pointer_t = typename std::add_pointer<T>::type;
template <typename... Ts>
using common_type_t = typename std::common_type<Ts...>::type;
template <typename T>
using decay_t = typename std::decay<T>::type;
template <bool B, typename T = void>
using enable_if_t = typename std::enable_if<B, T>::type;
template <typename T>
using remove_const_t = typename std::remove_const<T>::type;
template <typename T>
using remove_reference_t = typename std::remove_reference<T>::type;
template <typename T>
inline constexpr T&& forward(remove_reference_t<T>& t) noexcept
{
return static_cast<T&&>(t);
}
template <typename T>
inline constexpr T&& forward(remove_reference_t<T>&& t) noexcept
{
static_assert(!std::is_lvalue_reference<T>::value, "can not forward an rvalue as an lvalue");
return static_cast<T&&>(t);
}
template <typename T>
constexpr remove_reference_t<T>&& move(T&& t) noexcept
{
return static_cast<remove_reference_t<T>&&>(t);
}
#ifdef MPARK_INTEGER_SEQUENCE
template <typename T, T... Is>
using integer_sequence = std::integer_sequence<T, Is...>;
template <std::size_t... Is>
using index_sequence = std::index_sequence<Is...>;
template <std::size_t N>
using make_index_sequence = std::make_index_sequence<N>;
template <typename... Ts>
using index_sequence_for = std::index_sequence_for<Ts...>;
#else
template <typename T, T... Is>
struct integer_sequence
{
using value_type = T;
static constexpr std::size_t size() noexcept { return sizeof...(Is); }
};
template <std::size_t... Is>
using index_sequence = integer_sequence<std::size_t, Is...>;
template <typename Lhs, typename Rhs>
struct make_index_sequence_concat;
template <std::size_t... Lhs, std::size_t... Rhs>
struct make_index_sequence_concat<index_sequence<Lhs...>, index_sequence<Rhs...>>
: identity<index_sequence<Lhs..., (sizeof...(Lhs) + Rhs)...>>
{
};
template <std::size_t N>
struct make_index_sequence_impl;
template <std::size_t N>
using make_index_sequence = typename make_index_sequence_impl<N>::type;
template <std::size_t N>
struct make_index_sequence_impl
: make_index_sequence_concat<make_index_sequence<N / 2>, make_index_sequence<N - (N / 2)>>
{
};
template <>
struct make_index_sequence_impl<0> : identity<index_sequence<>>
{
};
template <>
struct make_index_sequence_impl<1> : identity<index_sequence<0>>
{
};
template <typename... Ts>
using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
#endif
// <functional>
#ifdef MPARK_TRANSPARENT_OPERATORS
using equal_to = std::equal_to<>;
#else
struct equal_to
{
template <typename Lhs, typename Rhs>
inline constexpr auto operator()(Lhs&& lhs, Rhs&& rhs) const
RETURN(lib::forward<Lhs>(lhs) == lib::forward<Rhs>(rhs))
};
#endif
#ifdef MPARK_TRANSPARENT_OPERATORS
using not_equal_to = std::not_equal_to<>;
#else
struct not_equal_to
{
template <typename Lhs, typename Rhs>
inline constexpr auto operator()(Lhs&& lhs, Rhs&& rhs) const
RETURN(lib::forward<Lhs>(lhs) != lib::forward<Rhs>(rhs))
};
#endif
#ifdef MPARK_TRANSPARENT_OPERATORS
using less = std::less<>;
#else
struct less
{
template <typename Lhs, typename Rhs>
inline constexpr auto operator()(Lhs&& lhs, Rhs&& rhs) const
RETURN(lib::forward<Lhs>(lhs) < lib::forward<Rhs>(rhs))
};
#endif
#ifdef MPARK_TRANSPARENT_OPERATORS
using greater = std::greater<>;
#else
struct greater
{
template <typename Lhs, typename Rhs>
inline constexpr auto operator()(Lhs&& lhs, Rhs&& rhs) const
RETURN(lib::forward<Lhs>(lhs) > lib::forward<Rhs>(rhs))
};
#endif
#ifdef MPARK_TRANSPARENT_OPERATORS
using less_equal = std::less_equal<>;
#else
struct less_equal
{
template <typename Lhs, typename Rhs>
inline constexpr auto operator()(Lhs&& lhs, Rhs&& rhs) const
RETURN(lib::forward<Lhs>(lhs) <= lib::forward<Rhs>(rhs))
};
#endif
#ifdef MPARK_TRANSPARENT_OPERATORS
using greater_equal = std::greater_equal<>;
#else
struct greater_equal
{
template <typename Lhs, typename Rhs>
inline constexpr auto operator()(Lhs&& lhs, Rhs&& rhs) const
RETURN(lib::forward<Lhs>(lhs) >= lib::forward<Rhs>(rhs))
};
#endif
} // namespace cpp14
inline namespace cpp17
{
// <type_traits>
template <bool B>
using bool_constant = std::integral_constant<bool, B>;
template <typename...>
using void_t = void;
namespace detail
{
namespace swappable
{
using std::swap;
template <typename T>
struct is_swappable_impl
{
private:
template <typename U, typename = decltype(swap(std::declval<U&>(), std::declval<U&>()))>
inline static std::true_type test(int);
template <typename U>
inline static std::false_type test(...);
public:
using type = decltype(test<T>(0));
};
template <typename T>
using is_swappable = typename is_swappable_impl<T>::type;
template <typename T, bool = is_swappable<T>::value>
struct is_nothrow_swappable
{
static constexpr bool value = noexcept(swap(std::declval<T&>(), std::declval<T&>()));
};
template <typename T>
struct is_nothrow_swappable<T, false> : std::false_type
{
};
} // namespace swappable
} // namespace detail
template <typename T>
using is_swappable = detail::swappable::is_swappable<T>;
template <typename T>
using is_nothrow_swappable = detail::swappable::is_nothrow_swappable<T>;
// <functional>
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4100)
#endif
template <typename F, typename... As>
inline constexpr auto invoke(F&& f, As&&... as) RETURN(lib::forward<F>(f)(lib::forward<As>(as)...))
#ifdef _MSC_VER
#pragma warning(pop)
#endif
template <typename B, typename T, typename D>
inline constexpr auto invoke(T B::*pmv, D&& d) RETURN(lib::forward<D>(d).*pmv)
template <typename Pmv, typename Ptr>
inline constexpr auto invoke(Pmv pmv, Ptr&& ptr) RETURN((*lib::forward<Ptr>(ptr)).*pmv)
template <typename B, typename T, typename D, typename... As>
inline constexpr auto invoke(T B::*pmf, D&& d, As&&... as)
RETURN((lib::forward<D>(d).*pmf)(lib::forward<As>(as)...))
template <typename Pmf, typename Ptr, typename... As>
inline constexpr auto invoke(Pmf pmf, Ptr&& ptr, As&&... as)
RETURN(((*lib::forward<Ptr>(ptr)).*pmf)(lib::forward<As>(as)...))
namespace detail
{
template <typename Void, typename, typename...>
struct invoke_result
{
};
template <typename F, typename... Args>
struct invoke_result<void_t<decltype(lib::invoke(std::declval<F>(), std::declval<Args>()...))>, F,
Args...>
: identity<decltype(lib::invoke(std::declval<F>(), std::declval<Args>()...))>
{
};
} // namespace detail
template <typename F, typename... Args>
using invoke_result = detail::invoke_result<void, F, Args...>;
template <typename F, typename... Args>
using invoke_result_t = typename invoke_result<F, Args...>::type;
namespace detail
{
template <typename Void, typename, typename...>
struct is_invocable : std::false_type
{
};
template <typename F, typename... Args>
struct is_invocable<void_t<invoke_result_t<F, Args...>>, F, Args...> : std::true_type
{
};
template <typename Void, typename, typename, typename...>
struct is_invocable_r : std::false_type
{
};
template <typename R, typename F, typename... Args>
struct is_invocable_r<void_t<invoke_result_t<F, Args...>>, R, F, Args...>
: std::is_convertible<invoke_result_t<F, Args...>, R>
{
};
} // namespace detail
template <typename F, typename... Args>
using is_invocable = detail::is_invocable<void, F, Args...>;
template <typename R, typename F, typename... Args>
using is_invocable_r = detail::is_invocable_r<void, R, F, Args...>;
// <memory>
#ifdef MPARK_BUILTIN_ADDRESSOF
template <typename T>
inline constexpr T* addressof(T& arg)
{
return __builtin_addressof(arg);
}
#else
namespace detail
{
namespace has_addressof_impl
{
struct fail;
template <typename T>
inline fail operator&(T&&);
template <typename T>
inline static constexpr bool impl()
{
return (std::is_class<T>::value || std::is_union<T>::value) &&
!std::is_same<decltype(&std::declval<T&>()), fail>::value;
}
} // namespace has_addressof_impl
template <typename T>
using has_addressof = bool_constant<has_addressof_impl::impl<T>()>;
template <typename T>
inline constexpr T* addressof(T& arg, std::true_type)
{
return std::addressof(arg);
}
template <typename T>
inline constexpr T* addressof(T& arg, std::false_type)
{
return &arg;
}
} // namespace detail
template <typename T>
inline constexpr T* addressof(T& arg)
{
return detail::addressof(arg, detail::has_addressof<T>{});
}
#endif
template <typename T>
inline constexpr T* addressof(const T&&) = delete;
} // namespace cpp17
template <typename T>
struct remove_all_extents : identity<T>
{
};
template <typename T, std::size_t N>
struct remove_all_extents<array<T, N>> : remove_all_extents<T>
{
};
template <typename T>
using remove_all_extents_t = typename remove_all_extents<T>::type;
template <std::size_t N>
using size_constant = std::integral_constant<std::size_t, N>;
template <bool... Bs>
using bool_sequence = integer_sequence<bool, Bs...>;
template <std::size_t I, typename T>
struct indexed_type : size_constant<I>, identity<T>
{
};
template <bool... Bs>
using all = std::is_same<bool_sequence<true, Bs...>, bool_sequence<Bs..., true>>;
#ifdef MPARK_TYPE_PACK_ELEMENT
template <std::size_t I, typename... Ts>
using type_pack_element_t = __type_pack_element<I, Ts...>;
#else
template <std::size_t I, typename... Ts>
struct type_pack_element_impl
{
private:
template <typename>
struct set;
template <std::size_t... Is>
struct set<index_sequence<Is...>> : indexed_type<Is, Ts>...
{
};
template <typename T>
inline static std::enable_if<true, T> impl(indexed_type<I, T>);
inline static std::enable_if<false> impl(...);
public:
using type = decltype(impl(set<index_sequence_for<Ts...>>{}));
};
template <std::size_t I, typename... Ts>
using type_pack_element = typename type_pack_element_impl<I, Ts...>::type;
template <std::size_t I, typename... Ts>
using type_pack_element_t = typename type_pack_element<I, Ts...>::type;
#endif
} // namespace lib
} // namespace mpark
#undef RETURN
#endif // MPARK_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...>> : lib::identity<lib::type_pack_element_t<I, Ts...>>
{
static_assert(I < sizeof...(Ts), "`variant_alternative` index out of range.");
};
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, std::is_trivially_copy_constructible, std::is_copy_constructible>()...);
static constexpr Trait move_constructible_trait = common_trait(
trait<Ts, std::is_trivially_move_constructible, std::is_move_constructible>()...);
static constexpr Trait copy_assignable_trait =
common_trait(copy_constructible_trait, move_constructible_trait,
trait<Ts, std::is_trivially_copy_assignable, std::is_copy_assignable>()...);
static constexpr Trait move_assignable_trait =
common_trait(move_constructible_trait,
trait<Ts, std::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, ::std::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, ::std::in_place_index_t<I>)
{
return get_alt(lib::forward<V>(v).tail_, ::std::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, ::std::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(lib::forward<V>(v).data_,
::std::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(::std::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(::std::in_place_index_t<0>, Args&&... args) \
: head_(::std::in_place_t{}, lib::forward<Args>(args)...) \
{ \
} \
\
template <std::size_t I, typename... Args> \
inline explicit constexpr recursive_union(::std::in_place_index_t<I>, Args&&... args) \
: tail_(::std::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(::std::in_place_index_t<I>, Args&&... args)
: data_(::std::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:
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); }
inline static constexpr std::size_t size() { return sizeof...(Ts); }
recursive_union<DestructibleTrait, 0, Ts...> 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>(::std::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,
std::is_lvalue_reference<That>{});
}
assignment* self;
};
#endif
template <bool CopyAssign, std::size_t I, typename T, typename Arg>
inline void assign_alt(alt<I, T>& a, Arg&& arg, lib::bool_constant<CopyAssign> tag)
{
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>(T(lib::forward<Arg>(arg_))); }
void operator()(std::false_type) const { this_->emplace<I>(lib::forward<Arg>(arg_)); }
assignment* this_;
Arg&& arg_;
} impl{this, lib::forward<Arg>(arg)};
impl(tag);
}
}
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,
std::is_lvalue_reference<That>{});
}
#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), std::false_type{});
}
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;
} // 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_(::std::in_place_index_t<0>{})
{
}
variant(const variant&) = default;
variant(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_constructible<T, Arg>::value, int> = 0>
inline constexpr variant(Arg&& arg) noexcept(std::is_nothrow_constructible<T, Arg>::value)
: impl_(::std::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(::std::in_place_index_t<I>, Args&&... args) noexcept(
std::is_nothrow_constructible<T, Args...>::value)
: impl_(::std::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(
::std::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_(::std::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(::std::in_place_type_t<T>, Args&&... args) noexcept(
std::is_nothrow_constructible<T, Args...>::value)
: impl_(::std::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(
::std::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_(::std::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
namespace std
{
using mpark::variant;
using mpark::visit;
using mpark::holds_alternative;
using mpark::get;
using mpark::get_if;
using mpark::monostate;
using mpark::bad_variant_access;
using mpark::variant_size;
using mpark::variant_alternative;
using mpark::variant_alternative_t;
} // namespace std
#endif
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