[Patch] Implement std::experimental::variant
Tim Shen
timshen@google.com
Sat Aug 6 05:46:00 GMT 2016
On Fri, Aug 5, 2016 at 4:08 AM, Jonathan Wakely <jwakely@redhat.com> wrote:
>> --- a/libstdc++-v3/include/bits/uses_allocator.h
>> +++ b/libstdc++-v3/include/bits/uses_allocator.h
>> @@ -113,6 +113,51 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>> constexpr bool uses_allocator_v = uses_allocator<_Tp, _Alloc>::value;
>> #endif // C++17
>>
>> + template<typename _Tp, typename _Alloc, typename... _Args>
>> + struct __is_uses_allocator_constructible
>> + : conditional<uses_allocator<_Tp, _Alloc>::value,
>> + __or_<is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>,
>> + is_constructible<_Tp, _Args..., _Alloc>>,
>> + is_constructible<_Tp, _Args...>>::type { };
>> +
>> + template<typename _Tp, typename _Alloc, typename... _Args>
>> + static constexpr bool __is_uses_allocator_constructible_v =
>> + __is_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
>
>
> This doesn't need to be 'static'
Done.
>
>
>> + template<typename _Tp, typename _Alloc, typename... _Args>
>> + struct __is_nothrow_uses_allocator_constructible
>> + : conditional<uses_allocator<_Tp, _Alloc>::value,
>> + __or_<is_nothrow_constructible<_Tp, allocator_arg_t, _Alloc,
>> _Args...>,
>> + is_nothrow_constructible<_Tp, _Args..., _Alloc>>,
>> + is_nothrow_constructible<_Tp, _Args...>>::type { };
>
>
> I wonder if there's any benefit to removing the duplication in the
> definitions of __is_nothrow_uses_allocator_constructible and
> __is_uses_allocator_constructible by defining a single template that
> can be instantation with either is_constructible or
> is_nothrow_constructible as needed:
>
> template<template<typename, typename...> class _Trait, typename _Tp,
> typename _Alloc, typename... _Args>
> struct __is_uses_allocator_constructible_impl
> : conditional<uses_allocator<_Tp, _Alloc>::value,
> __or_<_Trait<_Tp, allocator_arg_t, _Alloc, _Args...>,
> _Trait<_Tp, _Args..., _Alloc>>,
> _Trait<_Tp, _Args...>>::type { };
>
> template<typename _Tp, typename _Alloc, typename... _Args>
> using __is_uses_allocator_constructible
> = __is_uses_allocator_constructible_impl<is_constructible,
> _Tp, _Alloc, _Args...>;
>
> template<typename _Tp, typename _Alloc, typename... _Args>
> using __is_nothrow_uses_allocator_constructible
> = __is_uses_allocator_constructible_impl<is_nothrow_constructible,
> _Tp, _Alloc, _Args...>;
>
> What do you think?
>
> (The variable templates would be unchanged).
Done. I don't have strong opinion on this.
>
>
>> +
>> + template<typename _Tp, typename _Alloc, typename... _Args>
>> + static constexpr bool __is_nothrow_uses_allocator_constructible_v =
>> + __is_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
>
>
> This should be using __is_nothrow_uses_allocator_constructible
> (and doesn't need to be static)
Good catch. :)
>
>
>
>> +
>> + template<typename _Tp, typename... _Args>
>> + void __uses_allocator_construct_impl(__uses_alloc0 __a, _Tp* __ptr,
>> + _Args&&... __args)
>> + { new (__ptr) _Tp(forward<_Args>(__args)...); }
>> +
>> + template<typename _Tp, typename _Alloc, typename... _Args>
>> + void __uses_allocator_construct_impl(__uses_alloc1<_Alloc> __a, _Tp*
>> __ptr,
>> + _Args&&... __args)
>> + { new (__ptr) _Tp(allocator_arg, *__a._M_a,
>> forward<_Args>(__args)...); }
>> +
>> + template<typename _Tp, typename _Alloc, typename... _Args>
>> + void __uses_allocator_construct_impl(__uses_alloc2<_Alloc> __a, _Tp*
>> __ptr,
>> + _Args&&... __args)
>> + { new (__ptr) _Tp(forward<_Args>(__args)..., *__a._M_a); }
>
>
> I think these all need to use ::new (__ptr) with qualification, see
> below.
Done. I didn't add a testcase for this. Do you think that we need one/some?
>
>
>> +/** @file variant
>> + * This is a TS C++ Library header.
>
>
> This should be updated.
Done.
>
>> + */
>> +
>> +#ifndef _GLIBCXX_VARIANT
>> +#define _GLIBCXX_VARIANT 1
>> +
>> +#pragma GCC system_header
>> +
>> +#if __cplusplus <= 201103L
>
>
> This should be 201402L
Done.
>
>> +# include <bits/c++17_warning.h>
>> +#else
>> +
>> +#include <tuple>
>> +#include <type_traits>
>> +#include <utility>
>> +#include <bits/enable_special_members.h>
>> +#include <bits/uses_allocator.h>
>> +
>> +namespace std _GLIBCXX_VISIBILITY(default)
>> +{
>> +_GLIBCXX_BEGIN_NAMESPACE_VERSION
>> +
>> + template<typename... _Types> class variant;
>> +
>> + template<typename _Variant>
>> + struct variant_size;
>> +
>> + template<typename _Variant>
>> + struct variant_size<const _Variant> : variant_size<_Variant> {};
>> +
>> + template<typename _Variant>
>> + struct variant_size<volatile _Variant> : variant_size<_Variant> {};
>> +
>> + template<typename _Variant>
>> + struct variant_size<const volatile _Variant> : variant_size<_Variant>
>> {};
>> +
>> + template<typename... _Types>
>> + struct variant_size<variant<_Types...>>
>> + : std::integral_constant<size_t, sizeof...(_Types)> {};
>> +
>> + template<typename _Variant>
>> + static constexpr size_t variant_size_v =
>> variant_size<_Variant>::value;
>
>
> We don't need 'static' here.
Done.
>
>> +
>> + template<size_t _Np, typename _Variant>
>> + struct variant_alternative;
>> +
>> + template<size_t _Np, typename _First, typename... _Rest>
>> + struct variant_alternative<_Np, variant<_First, _Rest...>>
>> + : variant_alternative<_Np-1, variant<_Rest...>> {};
>> +
>> + template<typename _First, typename... _Rest>
>> + struct variant_alternative<0, variant<_First, _Rest...>>
>> + { using type = _First; };
>> +
>> + template<size_t _Np, typename _Variant>
>> + using variant_alternative_t =
>> + typename variant_alternative<_Np, _Variant>::type;
>> +
>> + static constexpr size_t variant_npos = -1;
>
>
> Or here.
Done.
>
>> +
>> +namespace __detail
>> +{
>> +namespace __variant
>> +{
>> + // Returns the first apparence of _Tp in _Types.
>> + // Returns sizeof...(_Types) if _Tp is not in _Types.
>> + template<typename _Tp, typename... _Types>
>> + struct __index_of : std::integral_constant<size_t, 0> {};
>> +
>> + template<typename _Tp, typename... _Types>
>> + static constexpr size_t __index_of_v = __index_of<_Tp,
>> _Types...>::value;
>
>
> Or here.
Done.
>
>> + // Stores a void alternative, until void becomes a regular type.
>
>
> Personally I hope it won't become a regular type :-)
Sorry :)
Do you mind to share your insights?
> Let's say "because void is not a regault type" here. That avoids the
> comment becoming stale. If the language changes we'll need to update
> this bit of the code anyway. so the comment can be updated then too.
Done.
>
>> + return __reserved_type_map<_Qualified_storage, _Alternative>(
>> + *static_cast<_Storage*>(__ptr));
>> + }
>> +
>> + // Various functions as "vtable" entries, where those vtables are used
>> by
>> + // polymorphic operations.
>> + template<typename _Lhs, typename _Rhs>
>> + constexpr void
>> + __erased_ctor(void* __lhs, void* __rhs)
>> + { new (__lhs) decay_t<_Lhs>(__get_alternative<_Rhs>(__rhs)); }
>> +
>> + template<typename _Alloc, typename _Lhs, typename _Rhs>
>> + constexpr void
>> + __erased_use_alloc_ctor(const _Alloc& __a, void* __lhs, void* __rhs)
>> + {
>> + __uses_allocator_construct(__a, static_cast<decay_t<_Lhs>*>(__lhs),
>> + __get_alternative<_Rhs>(__rhs));
>> + }
>> +
>> + template<typename _Tp>
>> + constexpr void
>> + __erased_dtor(void* __ptr)
>> + {
>> + using _Storage = decay_t<_Tp>;
>> + static_cast<_Storage*>(__ptr)->~_Storage();
>> + }
>
>
> This is almost the same as the __exception_ptr::__dest_thunk(void*)
> function we're about to add with Gleb's patch. I wonder if we should
> reuse the same function in both places. We can do that later though.
Added a TODO.
>
>
>> + // For how many times does _Tp appear in _Tuple?
>> + template<typename _Tp, typename _Tuple>
>> + struct __tuple_count;
>> +
>> + template<typename _Tp, typename _Tuple>
>> + static constexpr size_t __tuple_count_v = __tuple_count<_Tp,
>> _Tuple>::value;
>> +
>> + template<typename _Tp, typename... _Types>
>> + struct __tuple_count<_Tp, tuple<_Types...>>
>> + : integral_constant<size_t, 0> { };
>> +
>> + template<typename _Tp, typename _First, typename... _Rest>
>> + struct __tuple_count<_Tp, tuple<_First, _Rest...>>
>> + : integral_constant<
>> + size_t,
>> + __tuple_count_v<_Tp, tuple<_Rest...>> + is_same_v<_Tp, _First>> {
>> };
>> +
>> + template<typename _Tp, typename... _Types>
>> + static constexpr bool __exactly_once =
>> + __tuple_count_v<_Tp, tuple<_Types...>> == 1;
>
>
> I was going to say we could reuse this nice utility in <tuple> for
> std::get<T> but actually our implementation does need to count the
> types, it just works by an implicit conversion to the unique base
> class with that type (and is ambiguous otherwise). We could use your
> __exactly_once to give a nice static assertion for invalid calls to
> std::get<T>, but that would add unnecessary compile-time overhead to
> valid calls. Anyway, that's another tangent that isn't relevant to
> variant ...
These are good thoughts! Added a TODO.
Removed static.
>
>
>> +
>> + // Takes _Types and create an overloaded _S_fun for each type.
>> + // If a type appears for more than one times in _Types,
>
>
> s/for more than one times/more than once/
Done.
>
>> + // only create one overload for it.
>> + template<typename... _Types>
>> + struct __overload_set
>> + { static void _S_fun(); };
>> +
>> + template<typename _First, typename... _Rest>
>> + struct __overload_set<_First, _Rest...> : __overload_set<_Rest...>
>> + {
>> + using __overload_set<_Rest...>::_S_fun;
>> + static integral_constant<size_t, sizeof...(_Rest)> _S_fun(_First);
>> + };
>> +
>> + template<typename... _Rest>
>> + struct __overload_set<void, _Rest...> : __overload_set<_Rest...>
>> + {
>> + using __overload_set<_Rest...>::_S_fun;
>> + };
>> +
>> + // Helper for variant(_Tp&&) and variant::operator=(_Tp&&).
>> + // __accepted_index maps the arbitrary _Tp to an alternative type in
>> _Variant.
>> + template<typename _Tp, typename _Variant, typename = void>
>> + struct __accepted_index
>> + { static constexpr size_t value = variant_npos; };
>> +
>> + template<typename _Tp, typename... _Types>
>> + struct __accepted_index<
>> + _Tp, variant<_Types...>,
>> + decltype(__overload_set<_Types...>::_S_fun(declval<_Tp>()),
>
>
> This I think all uses of declval<_Tp> need to be qualified with std::
>
>> + declval<void>())>
>
>
> (The decval<void>() case is OK as that won't do ADL).
Done for all of them, for consistency.
>
>> + template<typename _Array_type, typename _First, typename... _Rest,
>> + typename... _Args>
>> + struct __gen_vtable_impl<_Array_type, tuple<_First, _Rest...>,
>> + tuple<_Args...>>
>
>
> Do you actually need to use std::tuple here, or would something much
> more lightweight be OK too?
I actually just need a template to hold all alternatives. How about
forward declaring tuple, and not including the header?
I was totally unaware of the cost of <tuple>, and tried to use
tuple_cat() on a bunch of function calls:
(void)tuple_cat(foo<_Types>()...) where foo returns tuple<>.
But not we have fold expression \o/! So I can directly write:
(foo<_Types>, ...)
which is perfect.
>
> For example we have std::tr2::__reflection_typelist in
> <tr2/type_traits>. Or it looks like this could just use something even
> simpler:
> template<typename... T> struct __type_list
>
> What we really need is to standardize Eric Niebler's metapgroamming
> library, or Peter Dimov's one, or *anything* that gives us a set of
> nice tools for doing this stuff. std::tuple is a very heavyweight type
> to use for simple type lists.
I don't need the whole pack of metaprogramming tools here, lucky me. ;)
>
> It doesn't look like you're using any members of std::tuple, so maybe
> it won't actually instantiate any of the base classes or member
> functions, which is what would be inefficient.
>
>> + template<typename _Tp, typename... _Types>
>> + _Tp& get(variant<_Types...>& __v)
>
>
> Please add 'inline' to these one-line functions. All the get and
> get_if overloads are tiny.
What's the difference between non-inline function templates and inline
function templates? At some point you may already explained that to
me, but I'm still confused.
>
>> + template<typename... _Types>
>> + bool operator!=(const variant<_Types...>& __lhs,
>> + const variant<_Types...>& __rhs)
>> + { return !(__lhs == __rhs); }
>
>
> Inline.
Done.
>
>> + template<typename... _Types>
>> + bool operator>(const variant<_Types...>& __lhs,
>> + const variant<_Types...>& __rhs)
>> + { return __rhs < __lhs; }
>
>
> Inline.
Done.
>
>> + template<typename... _Types>
>> + bool operator<=(const variant<_Types...>& __lhs,
>> + const variant<_Types...>& __rhs)
>> + { return !(__lhs > __rhs); }
>
>
> etc. :-)
Done.
>
>> + constexpr bool operator<(monostate, monostate) noexcept
>> + { return false; }
>
>
> These are implicitly inline because of 'constexpr' so that's OK :-)
>
>> + template<size_t _Np, typename... _Args>
>> + void emplace(_Args&&... __args)
>> + {
>> + static_assert(_Np < sizeof...(_Types),
>> + "_Np should be in [0, number of alternatives)");
>> + this->~variant();
>> + __try
>> + {
>> + new (this) variant(in_place<_Np>,
>> + forward<_Args>(__args)...);
>
>
> I think this needs to be qualified: ::new (this) ...
>
> Otherwise you can't emplace some types into a variant:
>
> #include <cstddef>
> #include <new>
>
> struct foo {
> static void* operator new(std::size_t, void* p);
> };
>
> template<typename T>
> struct variant {
> alignas(T) char buf[sizeof(T)];
> void emplace(T t) {
> new (this) T(t);
> }
> };
>
> int main()
> {
> variant<foo> v;
> v.emplace( {} );
> }
>
> (We get this wrong in std::function too, which I'll fix).
Done.
>
>> + // To hornor algebraic data type, variant<> should be a bottom type,
>> which
>
>
> s/hornor/honor/
...Oops. :)
>
>> + // is 0 (as opposed to a void type, which is 1). Use incomplete type to
>> model
>> + // bottom type.
>> + template<> class variant<>;
>> +
>> + template<size_t _Np, typename... _Types>
>> + variant_alternative_t<_Np, variant<_Types...>>&
>> + get(variant<_Types...>& __v)
>> + {
>> + static_assert(_Np < sizeof...(_Types),
>> + "_Np should be in [0, number of alternatives)");
>
>
> I wonder if this message would be more user-friendly if it said
> "index" instead of "_Np", since _Np isn't a symbol the user will
> recognize. What do you think?
Done. Sorry, I don't always have time to care about user-friendliness.
When I do, I don't. ;)
>
>> + using argument_type = monostate;
>> +
>> + size_t
>> + operator()(const monostate& __t) const noexcept
>> + {
>> + constexpr size_t __magic_monostate_hash =
>> + static_cast<size_t>(-7777);
>> + return static_cast<size_t>(__magic_monostate_hash);
>
>
> Do we really need to static_cast<size_t> again when it's already a
> size_t? :-)
> Do we need either static_cast?
>
> constexpr size_t __magic_monostate_hash = -7777;
> return __magic_monostate_hash;
Done. I seriously have no idea why that will happen.
>
>> diff --git a/libstdc++-v3/testsuite/experimental/variant/compile.cc
>> b/libstdc++-v3/testsuite/experimental/variant/compile.cc
>> new file mode 100644
>> index 0000000..5cc7738
>> --- /dev/null
>> +++ b/libstdc++-v3/testsuite/experimental/variant/compile.cc
>> @@ -0,0 +1,392 @@
>> +// { dg-options "-std=gnu++17" }
>> +// { dg-do compile }
>> +
>> +// Copyright (C) 2016 Free Software Foundation, Inc.
>> +//
>> +// This file is part of the GNU ISO C++ Library. This library is free
>> +// software; you can redistribute it and/or modify it under the
>> +// terms of the GNU General Public License as published by the
>> +// Free Software Foundation; either version 3, or (at your option)
>> +// any later version.
>> +
>> +// This library is distributed in the hope that it will be useful,
>> +// but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> +// GNU General Public License for more details.
>> +
>> +// You should have received a copy of the GNU General Public License
>> along
>> +// with this library; see the file COPYING3. If not see
>> +// <http://www.gnu.org/licenses/>.
>> +
>> +#include <variant>
>> +#include <string>
>> +#include <vector>
>> +#include <testsuite_hooks.h>
>
>
> There's no need for testsuite_hooks.h in this { do-do compile } test.
>
> /endreview
>
>
> This is some truly impressive code, I'm not sure I understand all of
> it yet!
>
> As before, my only reservation is that this fails to compile, but
> should work (because the selected constructor for the chosen
> alternative is constexpr):
>
> #include <variant>
>
> struct literal {
> constexpr literal() = default;
> };
>
> struct nonliteral {
> nonliteral() { }
> };
>
> using namespace std;
> constexpr variant<literal, nonliteral> v{};
> constexpr variant<literal, nonliteral> v1{in_place_type<literal>};
> constexpr variant<literal, nonliteral> v2{in_place_index<0>};
Good news! This compiles now! I learned the technique from Anthony
Williams's implementation, whose code also compiles, but it requires a
close-to-trunk gcc, which implements
"...for unions, at least one non-static data member is of non-volatile
literal type, ...".
Also added it as a test.
Please verify the implementation by looking at _Uninitialized and
_Variant_storage.
>
>
> However, I think we could commit this for now as it's 99% complete.
> What do you think?
>
> I am concerned that if we commit this implementation now, and *don't*
> get a 100% conforming rewrite before we want to declare C++17 support
> stable and non-experimental, then we'd have to introduce an
> incompatible change. That could be done by replacing std::variant with
> std::_V2::variant, so it would still be possible.
>
> If you want to propose this for trunk please make the fixes noted
> above and send a new patch, CCing gcc-patches.
>
> Thanks!
>
>
I also moved the tests from experiemntal/variant to 20_util/variant.
Bootstrapped and tested on x86_64-linux-gnu.
Thank you all for reviewing all of these!
--
Regards,
Tim Shen
-------------- next part --------------
commit 68159483a1f0d7338d9de1771fd5c18d509ecf83
Author: Tim Shen <timshen@google.com>
Date: Fri Aug 5 22:29:40 2016 -0700
2016-08-05 Tim Shen <timshen@google.com>
Implement <variant>
* include/Makefile.am: Add new file std/variant.
* include/Makefile.in: Generated from Makefile.am.
* include/bits/enable_special_members.h: Add a tag type to allow
the construction in non-default constructor.
* include/bits/uses_allocator.h: Add convenience traits to
detect constructibility.
* include/std/variant: Implement <variant>.
* testsuite/20_util/variant/compile.cc: Compile-time tests.
* testsuite/20_util/variant/run.cc: Runtime tests.
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index e2c4f63..dda0253 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -77,6 +77,7 @@ std_headers = \
${std_srcdir}/unordered_set \
${std_srcdir}/utility \
${std_srcdir}/valarray \
+ ${std_srcdir}/variant \
${std_srcdir}/vector
bits_srcdir = ${glibcxx_srcdir}/include/bits
diff --git a/libstdc++-v3/include/Makefile.in b/libstdc++-v3/include/Makefile.in
index 882ff14..828673b 100644
--- a/libstdc++-v3/include/Makefile.in
+++ b/libstdc++-v3/include/Makefile.in
@@ -367,6 +367,7 @@ std_headers = \
${std_srcdir}/unordered_set \
${std_srcdir}/utility \
${std_srcdir}/valarray \
+ ${std_srcdir}/variant \
${std_srcdir}/vector
bits_srcdir = ${glibcxx_srcdir}/include/bits
diff --git a/libstdc++-v3/include/bits/enable_special_members.h b/libstdc++-v3/include/bits/enable_special_members.h
index 1ac8f38..07c6c99 100644
--- a/libstdc++-v3/include/bits/enable_special_members.h
+++ b/libstdc++-v3/include/bits/enable_special_members.h
@@ -36,13 +36,33 @@ namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
+ struct _Enable_default_constructor_tag
+ {
+ explicit _Enable_default_constructor_tag() = default;
+ };
+
/**
* @brief A mixin helper to conditionally enable or disable the default
* constructor.
* @sa _Enable_special_members
*/
template<bool _Switch, typename _Tag = void>
- struct _Enable_default_constructor { };
+ struct _Enable_default_constructor
+ {
+ constexpr _Enable_default_constructor() noexcept = default;
+ constexpr _Enable_default_constructor(_Enable_default_constructor const&)
+ noexcept = default;
+ constexpr _Enable_default_constructor(_Enable_default_constructor&&)
+ noexcept = default;
+ _Enable_default_constructor&
+ operator=(_Enable_default_constructor const&) noexcept = default;
+ _Enable_default_constructor&
+ operator=(_Enable_default_constructor&&) noexcept = default;
+
+ // Can be used in other ctors.
+ constexpr explicit
+ _Enable_default_constructor(_Enable_default_constructor_tag) { }
+ };
/**
@@ -86,7 +106,20 @@ template<bool _Default, bool _Destructor,
template<typename _Tag>
struct _Enable_default_constructor<false, _Tag>
- { constexpr _Enable_default_constructor() noexcept = delete; };
+ {
+ constexpr _Enable_default_constructor() noexcept = delete;
+ constexpr _Enable_default_constructor(_Enable_default_constructor const&)
+ noexcept = default;
+ constexpr _Enable_default_constructor(_Enable_default_constructor&&)
+ noexcept = default;
+ _Enable_default_constructor&
+ operator=(_Enable_default_constructor const&) noexcept = default;
+ _Enable_default_constructor&
+ operator=(_Enable_default_constructor&&) noexcept = default;
+
+ // Can be used in other ctors.
+ explicit _Enable_default_constructor(_Enable_default_constructor_tag) { }
+ };
template<typename _Tag>
struct _Enable_destructor<false, _Tag>
diff --git a/libstdc++-v3/include/bits/uses_allocator.h b/libstdc++-v3/include/bits/uses_allocator.h
index 46aea13..500bd90 100644
--- a/libstdc++-v3/include/bits/uses_allocator.h
+++ b/libstdc++-v3/include/bits/uses_allocator.h
@@ -113,6 +113,57 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
constexpr bool uses_allocator_v = uses_allocator<_Tp, _Alloc>::value;
#endif // C++17
+ template<template<typename...> class _Predicate,
+ typename _Tp, typename _Alloc, typename... _Args>
+ struct __is_uses_allocator_predicate
+ : conditional<uses_allocator<_Tp, _Alloc>::value,
+ __or_<_Predicate<_Tp, allocator_arg_t, _Alloc, _Args...>,
+ _Predicate<_Tp, _Args..., _Alloc>>,
+ _Predicate<_Tp, _Args...>>::type { };
+
+ template<typename _Tp, typename _Alloc, typename... _Args>
+ struct __is_uses_allocator_constructible
+ : __is_uses_allocator_predicate<is_constructible, _Tp, _Alloc, _Args...>
+ { };
+
+ template<typename _Tp, typename _Alloc, typename... _Args>
+ constexpr bool __is_uses_allocator_constructible_v =
+ __is_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
+
+ template<typename _Tp, typename _Alloc, typename... _Args>
+ struct __is_nothrow_uses_allocator_constructible
+ : __is_uses_allocator_predicate<is_nothrow_constructible,
+ _Tp, _Alloc, _Args...>
+ { };
+
+
+ template<typename _Tp, typename _Alloc, typename... _Args>
+ constexpr bool __is_nothrow_uses_allocator_constructible_v =
+ __is_nothrow_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
+
+ template<typename _Tp, typename... _Args>
+ void __uses_allocator_construct_impl(__uses_alloc0 __a, _Tp* __ptr,
+ _Args&&... __args)
+ { new (__ptr) _Tp(forward<_Args>(__args)...); }
+
+ template<typename _Tp, typename _Alloc, typename... _Args>
+ void __uses_allocator_construct_impl(__uses_alloc1<_Alloc> __a, _Tp* __ptr,
+ _Args&&... __args)
+ { new (__ptr) _Tp(allocator_arg, *__a._M_a, forward<_Args>(__args)...); }
+
+ template<typename _Tp, typename _Alloc, typename... _Args>
+ void __uses_allocator_construct_impl(__uses_alloc2<_Alloc> __a, _Tp* __ptr,
+ _Args&&... __args)
+ { new (__ptr) _Tp(forward<_Args>(__args)..., *__a._M_a); }
+
+ template<typename _Tp, typename _Alloc, typename... _Args>
+ void __uses_allocator_construct(const _Alloc& __a, _Tp* __ptr,
+ _Args&&... __args)
+ {
+ __uses_allocator_construct_impl(__use_alloc<_Tp, _Alloc, _Args...>(__a),
+ __ptr, forward<_Args>(__args)...);
+ }
+
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant
new file mode 100644
index 0000000..a9b4394
--- /dev/null
+++ b/libstdc++-v3/include/std/variant
@@ -0,0 +1,1360 @@
+// <variant> -*- C++ -*-
+
+// Copyright (C) 2016 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+/** @file variant
+ * This is the <variant> C++ Library header.
+ */
+
+#ifndef _GLIBCXX_VARIANT
+#define _GLIBCXX_VARIANT 1
+
+#pragma GCC system_header
+
+#if __cplusplus <= 201402L
+# include <bits/c++17_warning.h>
+#else
+
+#include <type_traits>
+#include <utility>
+#include <bits/enable_special_members.h>
+#include <bits/uses_allocator.h>
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+ template<typename... _Types> class tuple;
+ template<typename... _Types> class variant;
+ template <typename> struct hash;
+
+ template<typename _Variant>
+ struct variant_size;
+
+ template<typename _Variant>
+ struct variant_size<const _Variant> : variant_size<_Variant> {};
+
+ template<typename _Variant>
+ struct variant_size<volatile _Variant> : variant_size<_Variant> {};
+
+ template<typename _Variant>
+ struct variant_size<const volatile _Variant> : variant_size<_Variant> {};
+
+ template<typename... _Types>
+ struct variant_size<variant<_Types...>>
+ : std::integral_constant<size_t, sizeof...(_Types)> {};
+
+ template<typename _Variant>
+ constexpr size_t variant_size_v = variant_size<_Variant>::value;
+
+ template<size_t _Np, typename _Variant>
+ struct variant_alternative;
+
+ template<size_t _Np, typename _First, typename... _Rest>
+ struct variant_alternative<_Np, variant<_First, _Rest...>>
+ : variant_alternative<_Np-1, variant<_Rest...>> {};
+
+ template<typename _First, typename... _Rest>
+ struct variant_alternative<0, variant<_First, _Rest...>>
+ { using type = _First; };
+
+ template<size_t _Np, typename _Variant>
+ using variant_alternative_t =
+ typename variant_alternative<_Np, _Variant>::type;
+
+ constexpr size_t variant_npos = -1;
+
+namespace __detail
+{
+namespace __variant
+{
+ // Returns the first apparence of _Tp in _Types.
+ // Returns sizeof...(_Types) if _Tp is not in _Types.
+ template<typename _Tp, typename... _Types>
+ struct __index_of : std::integral_constant<size_t, 0> {};
+
+ template<typename _Tp, typename... _Types>
+ constexpr size_t __index_of_v = __index_of<_Tp, _Types...>::value;
+
+ template<typename _Tp, typename _First, typename... _Rest>
+ struct __index_of<_Tp, _First, _Rest...> :
+ std::integral_constant<size_t, is_same_v<_Tp, _First>
+ ? 0 : __index_of_v<_Tp, _Rest...> + 1> {};
+
+ // Extract _From's qualifiers and references and apply it to _To.
+ // __reserved_type_map<const int&, char> is const char&.
+ template<typename _From, typename _To>
+ struct __reserved_type_map_impl
+ { using type = _To; };
+
+ template<typename _From, typename _To>
+ using __reserved_type_map =
+ typename __reserved_type_map_impl<_From, _To>::type;
+
+ template<typename _From, typename _To>
+ struct __reserved_type_map_impl<_From&, _To>
+ { using type = add_lvalue_reference_t<__reserved_type_map<_From, _To>>; };
+
+ template<typename _From, typename _To>
+ struct __reserved_type_map_impl<_From&&, _To>
+ { using type = add_rvalue_reference_t<__reserved_type_map<_From, _To>>; };
+
+ template<typename _From, typename _To>
+ struct __reserved_type_map_impl<const _From, _To>
+ { using type = add_const_t<__reserved_type_map<_From, _To>>; };
+
+ template<typename _From, typename _To>
+ struct __reserved_type_map_impl<volatile _From, _To>
+ { using type = add_volatile_t<__reserved_type_map<_From, _To>>; };
+
+ template<typename _From, typename _To>
+ struct __reserved_type_map_impl<const volatile _From, _To>
+ { using type = add_cv_t<__reserved_type_map<_From, _To>>; };
+
+ // Stores a reference alternative as a... well, reference.
+ template<typename _Reference>
+ struct _Reference_storage
+ {
+ static_assert(is_reference_v<_Reference>,
+ "BUG: _Reference should be a reference");
+
+ _Reference_storage(_Reference __ref) noexcept : _M_storage(__ref) { }
+
+ operator _Reference() noexcept
+ { return static_cast<_Reference>(_M_storage); }
+
+ _Reference _M_storage;
+ };
+
+ // Stores a void alternative, because it is not a regular type.
+ template<typename _Void>
+ struct _Void_storage { };
+
+ // Map from the alternative type to a non-qualified storage type.
+ template<typename _Alternative, typename = void>
+ struct __storage_type
+ { using type = _Alternative; };
+
+ template<typename _Alternative>
+ struct __storage_type<_Alternative,
+ enable_if_t<is_reference_v<_Alternative>>>
+ { using type = _Reference_storage<_Alternative>; };
+
+ template<typename _Alternative>
+ struct __storage_type<_Alternative, enable_if_t<is_void_v<_Alternative>>>
+ { using type = _Void_storage<_Alternative>; };
+
+ template<typename _Type>
+ using __storage = typename __storage_type<_Type>::type;
+
+ template<typename _Type, bool __is_literal = std::is_literal_type_v<_Type>>
+ struct _Uninitialized;
+
+ template<typename _Type>
+ struct _Uninitialized<_Type, true>
+ {
+ constexpr _Uninitialized() = default;
+
+ template<typename... _Args>
+ constexpr _Uninitialized(in_place_index_t<0>, _Args&&... __args)
+ : _M_storage(std::forward<_Args>(__args)...)
+ { }
+
+ _Type _M_storage;
+ };
+
+ template<typename _Type>
+ struct _Uninitialized<_Type, false>
+ {
+ constexpr _Uninitialized() = default;
+
+ template<typename... _Args>
+ constexpr _Uninitialized(in_place_index_t<0>, _Args&&... __args)
+ { ::new (&_M_storage) _Type(std::forward<_Args>(__args)...); }
+
+ typename std::aligned_storage<sizeof(_Type), alignof(_Type)>::type
+ _M_storage;
+ };
+
+ // Reverse mapping of __storage_type.
+ template<typename _Storage_type>
+ struct __alternative_type
+ {
+ static_assert(!is_reference_v<_Storage_type>,
+ "BUG: _Storage_type should not be reference");
+ using type = _Storage_type;
+ };
+
+ template<typename _Reference>
+ struct __alternative_type<_Reference_storage<_Reference>>
+ { using type = _Reference; };
+
+ template<typename _Void>
+ struct __alternative_type<_Void_storage<_Void>>
+ { using type = _Void; };
+
+ // Given a qualified storage type, return the desired reference.
+ // The qualified storage type is supposed to carry the variant object's
+ // qualifications and reference information, and the designated alternative's
+ // storage type.
+ // Returns the qualification-collapsed alternative references.
+ //
+ // For example, __get_alternative<_Reference_storage<int&&>&> returns int&.
+ template<typename _Qualified_storage>
+ decltype(auto)
+ __get_alternative(void* __ptr)
+ {
+ using _Storage = decay_t<_Qualified_storage>;
+ using _Alternative = typename __alternative_type<_Storage>::type;
+ return __reserved_type_map<_Qualified_storage, _Alternative>(
+ *static_cast<_Storage*>(__ptr));
+ }
+
+ // Various functions as "vtable" entries, where those vtables are used by
+ // polymorphic operations.
+ template<typename _Lhs, typename _Rhs>
+ constexpr void
+ __erased_ctor(void* __lhs, void* __rhs)
+ { ::new (__lhs) decay_t<_Lhs>(__get_alternative<_Rhs>(__rhs)); }
+
+ template<typename _Alloc, typename _Lhs, typename _Rhs>
+ constexpr void
+ __erased_use_alloc_ctor(const _Alloc& __a, void* __lhs, void* __rhs)
+ {
+ __uses_allocator_construct(__a, static_cast<decay_t<_Lhs>*>(__lhs),
+ __get_alternative<_Rhs>(__rhs));
+ }
+
+ // TODO: Find a potential chance to reuse this accross the project.
+ template<typename _Tp>
+ constexpr void
+ __erased_dtor(void* __ptr)
+ {
+ using _Storage = decay_t<_Tp>;
+ static_cast<_Storage*>(__ptr)->~_Storage();
+ }
+
+ template<typename _Lhs, typename _Rhs>
+ constexpr void
+ __erased_assign(void* __lhs, void* __rhs)
+ { __get_alternative<_Lhs>(__lhs) = __get_alternative<_Rhs>(__rhs); }
+
+ template<typename _Lhs, typename _Rhs>
+ constexpr void
+ __erased_swap(void* __lhs, void* __rhs)
+ {
+ using std::swap;
+ swap(__get_alternative<_Lhs>(__lhs), __get_alternative<_Rhs>(__rhs));
+ }
+
+ template<typename _Lhs, typename _Rhs>
+ constexpr bool
+ __erased_equal_to(void* __lhs, void* __rhs)
+ { return __get_alternative<_Lhs>(__lhs) == __get_alternative<_Rhs>(__rhs); }
+
+ template<typename _Lhs, typename _Rhs>
+ constexpr bool
+ __erased_less_than(void* __lhs, void* __rhs)
+ { return __get_alternative<_Lhs>(__lhs) < __get_alternative<_Rhs>(__rhs); }
+
+ template<typename _Tp>
+ constexpr size_t
+ __erased_hash(void* __t)
+ { return std::hash<decay_t<_Tp>>{}(__get_alternative<_Tp>(__t)); }
+
+ template<typename... _Types>
+ struct _Variant_base;
+
+ template<typename... _Types>
+ struct _Variant_storage
+ { constexpr _Variant_storage() = default; };
+
+ // Use recursive unions to implement a trivially destructible variant.
+ template<typename _First, typename... _Rest>
+ struct _Variant_storage<_First, _Rest...>
+ {
+ constexpr _Variant_storage() = default;
+
+ template<typename... _Args>
+ constexpr _Variant_storage(in_place_index_t<0>, _Args&&... __args)
+ : _M_first(in_place<0>, forward<_Args>(__args)...)
+ { }
+
+ template<size_t _Np, typename... _Args,
+ typename = enable_if_t<0 < _Np && _Np < sizeof...(_Rest) + 1>>
+ constexpr _Variant_storage(in_place_index_t<_Np>, _Args&&... __args)
+ : _M_rest(in_place<_Np - 1>, forward<_Args>(__args)...)
+ { }
+
+ ~_Variant_storage() = default;
+
+ constexpr void*
+ _M_storage() const
+ {
+ return const_cast<void*>(
+ static_cast<const void*>(&_M_first._M_storage));
+ }
+
+ union
+ {
+ _Uninitialized<__storage<_First>> _M_first;
+ _Variant_storage<_Rest...> _M_rest;
+ };
+ };
+
+ template<typename _Derived, bool __is_trivially_destructible>
+ struct _Dtor_mixin
+ {
+ ~_Dtor_mixin()
+ { static_cast<_Derived*>(this)->_M_destroy(); }
+ };
+
+ template<typename _Derived>
+ struct _Dtor_mixin<_Derived, true>
+ {
+ ~_Dtor_mixin() = default;
+ };
+
+ // Helps SFINAE on special member functions. Otherwise it can live in variant
+ // class.
+ template<typename... _Types>
+ struct _Variant_base :
+ _Variant_storage<_Types...>,
+ _Dtor_mixin<_Variant_base<_Types...>,
+ __and_<std::is_trivially_destructible<_Types>...>::value>
+ {
+ using _Storage = _Variant_storage<_Types...>;
+
+ constexpr
+ _Variant_base()
+ noexcept(is_nothrow_default_constructible_v<
+ variant_alternative_t<0, variant<_Types...>>>)
+ : _Variant_base(in_place<0>) { }
+
+ _Variant_base(const _Variant_base& __rhs)
+ : _Storage(), _M_index(__rhs._M_index)
+ {
+ if (__rhs._M_valid())
+ {
+ static constexpr void (*_S_vtable[])(void*, void*) =
+ { &__erased_ctor<__storage<_Types>&,
+ const __storage<_Types>&>... };
+ _S_vtable[__rhs._M_index](_M_storage(), __rhs._M_storage());
+ }
+ }
+
+ _Variant_base(_Variant_base&& __rhs)
+ noexcept(__and_<is_nothrow_move_constructible<_Types>...>::value)
+ : _Storage(), _M_index(__rhs._M_index)
+ {
+ if (__rhs._M_valid())
+ {
+ static constexpr void (*_S_vtable[])(void*, void*) =
+ { &__erased_ctor<__storage<_Types>&, __storage<_Types>&&>... };
+ _S_vtable[__rhs._M_index](_M_storage(), __rhs._M_storage());
+ }
+ }
+
+ template<size_t _Np, typename... _Args>
+ constexpr explicit
+ _Variant_base(in_place_index_t<_Np> __i, _Args&&... __args)
+ : _Storage(__i, forward<_Args>(__args)...), _M_index(_Np)
+ { }
+
+ template<typename _Alloc>
+ _Variant_base(const _Alloc& __a, const _Variant_base& __rhs)
+ : _Storage(), _M_index(__rhs._M_index)
+ {
+ if (__rhs._M_valid())
+ {
+ static constexpr void
+ (*_S_vtable[])(const _Alloc&, void*, void*) =
+ { &__erased_use_alloc_ctor<_Alloc, __storage<_Types>&,
+ const __storage<_Types>&>... };
+ _S_vtable[__rhs._M_index](__a, _M_storage(), __rhs._M_storage());
+ }
+ }
+
+ template<typename _Alloc>
+ _Variant_base(const _Alloc& __a, _Variant_base&& __rhs)
+ : _Storage(), _M_index(__rhs._M_index)
+ {
+ if (__rhs._M_valid())
+ {
+ static constexpr void
+ (*_S_vtable[])(const _Alloc&, void*, void*) =
+ { &__erased_use_alloc_ctor<_Alloc, __storage<_Types>&,
+ __storage<_Types>&&>... };
+ _S_vtable[__rhs._M_index](__a, _M_storage(), __rhs._M_storage());
+ }
+ }
+
+ template<typename _Alloc, size_t _Np, typename... _Args>
+ constexpr explicit
+ _Variant_base(const _Alloc& __a, in_place_index_t<_Np>,
+ _Args&&... __args)
+ : _Storage(), _M_index(_Np)
+ {
+ using _Storage =
+ __storage<variant_alternative_t<_Np, variant<_Types...>>>;
+ __uses_allocator_construct(__a, static_cast<_Storage*>(_M_storage()),
+ forward<_Args>(__args)...);
+ __glibcxx_assert(_M_index == _Np);
+ }
+
+ _Variant_base&
+ operator=(const _Variant_base& __rhs)
+ {
+ if (_M_index == __rhs._M_index)
+ {
+ if (__rhs._M_valid())
+ {
+ static constexpr void (*_S_vtable[])(void*, void*) =
+ { &__erased_assign<__storage<_Types>&,
+ const __storage<_Types>&>... };
+ _S_vtable[__rhs._M_index](_M_storage(), __rhs._M_storage());
+ }
+ }
+ else
+ {
+ _Variant_base __tmp(__rhs);
+ this->~_Variant_base();
+ __try
+ {
+ ::new (this) _Variant_base(std::move(__tmp));
+ }
+ __catch (...)
+ {
+ _M_index = variant_npos;
+ __throw_exception_again;
+ }
+ }
+ __glibcxx_assert(_M_index == __rhs._M_index);
+ return *this;
+ }
+
+ _Variant_base&
+ operator=(_Variant_base&& __rhs)
+ noexcept(__and_<is_nothrow_move_constructible<_Types>...,
+ is_nothrow_move_assignable<_Types>...>::value)
+ {
+ if (_M_index == __rhs._M_index)
+ {
+ if (__rhs._M_valid())
+ {
+ static constexpr void (*_S_vtable[])(void*, void*) =
+ { &__erased_assign<__storage<_Types>&,
+ __storage<_Types>&&>... };
+ _S_vtable[__rhs._M_index](_M_storage(), __rhs._M_storage());
+ }
+ }
+ else
+ {
+ this->~_Variant_base();
+ __try
+ {
+ ::new (this) _Variant_base(std::move(__rhs));
+ }
+ __catch (...)
+ {
+ _M_index = variant_npos;
+ __throw_exception_again;
+ }
+ }
+ return *this;
+ }
+
+ void _M_destroy()
+ {
+ if (_M_valid())
+ {
+ static constexpr void (*_S_vtable[])(void*) =
+ { &__erased_dtor<__storage<_Types>&>... };
+ _S_vtable[this->_M_index](_M_storage());
+ }
+ }
+
+ constexpr void*
+ _M_storage() const
+ { return _Storage::_M_storage(); }
+
+ constexpr bool
+ _M_valid() const noexcept
+ { return _M_index != variant_npos; }
+
+ size_t _M_index;
+ };
+
+ // For how many times does _Tp appear in _Tuple?
+ template<typename _Tp, typename _Tuple>
+ struct __tuple_count;
+
+ template<typename _Tp, typename _Tuple>
+ constexpr size_t __tuple_count_v = __tuple_count<_Tp, _Tuple>::value;
+
+ template<typename _Tp, typename... _Types>
+ struct __tuple_count<_Tp, tuple<_Types...>>
+ : integral_constant<size_t, 0> { };
+
+ template<typename _Tp, typename _First, typename... _Rest>
+ struct __tuple_count<_Tp, tuple<_First, _Rest...>>
+ : integral_constant<
+ size_t,
+ __tuple_count_v<_Tp, tuple<_Rest...>> + is_same_v<_Tp, _First>> { };
+
+ // TODO: Reuse this in <tuple> ?
+ template<typename _Tp, typename... _Types>
+ constexpr bool __exactly_once = __tuple_count_v<_Tp, tuple<_Types...>> == 1;
+
+ // Takes _Types and create an overloaded _S_fun for each type.
+ // If a type appears more than once in _Types, create only one overload.
+ template<typename... _Types>
+ struct __overload_set
+ { static void _S_fun(); };
+
+ template<typename _First, typename... _Rest>
+ struct __overload_set<_First, _Rest...> : __overload_set<_Rest...>
+ {
+ using __overload_set<_Rest...>::_S_fun;
+ static integral_constant<size_t, sizeof...(_Rest)> _S_fun(_First);
+ };
+
+ template<typename... _Rest>
+ struct __overload_set<void, _Rest...> : __overload_set<_Rest...>
+ {
+ using __overload_set<_Rest...>::_S_fun;
+ };
+
+ // Helper for variant(_Tp&&) and variant::operator=(_Tp&&).
+ // __accepted_index maps the arbitrary _Tp to an alternative type in _Variant.
+ template<typename _Tp, typename _Variant, typename = void>
+ struct __accepted_index
+ { static constexpr size_t value = variant_npos; };
+
+ template<typename _Tp, typename... _Types>
+ struct __accepted_index<
+ _Tp, variant<_Types...>,
+ decltype(__overload_set<_Types...>::_S_fun(std::declval<_Tp>()),
+ std::declval<void>())>
+ {
+ static constexpr size_t value = sizeof...(_Types) - 1
+ - decltype(__overload_set<_Types...>::
+ _S_fun(std::declval<_Tp>()))::value;
+ };
+
+ // Returns the raw storage for __v.
+ template<typename _Variant>
+ void* __get_storage(_Variant&& __v)
+ { return __v._M_storage(); }
+
+ // Returns the reference to the desired alternative.
+ // It is as unsafe as a reinterpret_cast.
+ template<typename _Tp, typename _Variant>
+ decltype(auto) __access(_Variant&& __v)
+ {
+ return __get_alternative<__reserved_type_map<_Variant&&, __storage<_Tp>>>(
+ __get_storage(forward<_Variant>(__v)));
+ }
+
+ // A helper used to create variadic number of _To types.
+ template<typename _From, typename _To>
+ using _To_type = _To;
+
+ // Call the actual visitor.
+ // _Args are qualified storage types.
+ template<typename _Visitor, typename... _Args>
+ decltype(auto) __visit_invoke(_Visitor&& __visitor,
+ _To_type<_Args, void*>... __ptrs)
+ {
+ return forward<_Visitor>(__visitor)(__get_alternative<_Args>(__ptrs)...);
+ }
+
+ // Used for storing multi-dimensional vtable.
+ template<typename _Tp, size_t... _Dimensions>
+ struct _Multi_array
+ {
+ constexpr const _Tp&
+ _M_access() const
+ { return _M_data; }
+
+ _Tp _M_data;
+ };
+
+ template<typename _Tp, size_t __first, size_t... __rest>
+ struct _Multi_array<_Tp, __first, __rest...>
+ {
+ template<typename... _Args>
+ constexpr const _Tp&
+ _M_access(size_t __first_index, _Args... __rest_indices) const
+ { return _M_arr[__first_index]._M_access(__rest_indices...); }
+
+ _Multi_array<_Tp, __rest...> _M_arr[__first];
+ };
+
+ // Creates a multi-dimensional vtable recursively.
+ // _Variant_tuple is initially the input from visit(), and gets gradually
+ // consumed.
+ // _Arg_tuple is enumerated alternative sequence, represented by a
+ // qualified storage.
+ //
+ // For example,
+ // visit([](auto, auto){},
+ // variant<int, char>(),
+ // variant<float, double, long double>())
+ // will trigger instantiations of:
+ // __gen_vtable_impl<_Multi_array<void(*)(void*, void*), 2, 3>,
+ // tuple<variant<int, char>,
+ // variant<float, double, long double>>,
+ // tuple<>>
+ // __gen_vtable_impl<_Multi_array<void(*)(void*, void*), 3>,
+ // tuple<variant<float, double, long double>>,
+ // tuple<int>>
+ // __gen_vtable_impl<_Multi_array<void(*)(void*, void*)>,
+ // tuple<>,
+ // tuple<int, float>>
+ // __gen_vtable_impl<_Multi_array<void(*)(void*, void*)>,
+ // tuple<>,
+ // tuple<int, double>>
+ // __gen_vtable_impl<_Multi_array<void(*)(void*, void*)>,
+ // tuple<>,
+ // tuple<int, long double>>
+ // __gen_vtable_impl<_Multi_array<void(*)(void*, void*), 3>,
+ // tuple<variant<float, double, long double>>,
+ // tuple<char>>
+ // __gen_vtable_impl<_Multi_array<void(*)(void*, void*)>,
+ // tuple<>,
+ // tuple<char, float>>
+ // __gen_vtable_impl<_Multi_array<void(*)(void*, void*)>,
+ // tuple<>,
+ // tuple<char, double>>
+ // __gen_vtable_impl<_Multi_array<void(*)(void*, void*)>,
+ // tuple<>,
+ // tuple<char, long double>>
+ // The returned multi-dimensional vtable can be fast accessed by the visitor
+ // using index calculation.
+ template<typename _Array_type, typename _Variant_tuple, typename _Arg_tuple>
+ struct __gen_vtable_impl;
+
+ template<typename _Array_type, typename _First, typename... _Rest,
+ typename... _Args>
+ struct __gen_vtable_impl<_Array_type, tuple<_First, _Rest...>,
+ tuple<_Args...>>
+ {
+ static constexpr _Array_type
+ _S_apply()
+ {
+ _Array_type __vtable{};
+ _S_apply_all_alts(
+ __vtable, make_index_sequence<variant_size_v<decay_t<_First>>>());
+ return __vtable;
+ }
+
+ template<size_t... __indices>
+ static constexpr void
+ _S_apply_all_alts(_Array_type& __vtable, index_sequence<__indices...>)
+ { (_S_apply_single_alt<__indices>(__vtable._M_arr[__indices]), ...); }
+
+ template<size_t __index>
+ static constexpr void
+ _S_apply_single_alt(auto& __element)
+ {
+ using _Alternative = variant_alternative_t<__index, decay_t<_First>>;
+ using _Qualified_storage = __reserved_type_map<
+ _First, __storage<_Alternative>>;
+ __element = __gen_vtable_impl<
+ decay_t<decltype(__element)>, tuple<_Rest...>,
+ tuple<_Args..., _Qualified_storage>>::_S_apply();
+ }
+ };
+
+ template<typename _Result_type, typename _Visitor, typename... _Args>
+ struct __gen_vtable_impl<
+ _Multi_array<_Result_type (*)(_Visitor, _To_type<_Args, void*>...)>,
+ tuple<>, tuple<_Args...>>
+ {
+ using _Array_type =
+ _Multi_array<_Result_type (*)(_Visitor&&, _To_type<_Args, void*>...)>;
+
+ static constexpr auto
+ _S_apply()
+ { return _Array_type{&__visit_invoke<_Visitor, _Args...>}; }
+ };
+
+ template<typename _Result_type, typename _Visitor, typename... _Variants>
+ struct __gen_vtable
+ {
+ using _Func_ptr =
+ _Result_type (*)(_Visitor&&, _To_type<_Variants, void*>...);
+ using _Array_type =
+ _Multi_array<_Func_ptr, variant_size_v<decay_t<_Variants>>...>;
+
+ static constexpr _Array_type
+ _S_apply()
+ {
+ return __gen_vtable_impl<
+ _Array_type, tuple<_Variants...>, tuple<>>::_S_apply();
+ }
+ };
+
+} // namespace __variant
+} // namespace __detail
+
+ template<typename _Tp, typename... _Types>
+ inline constexpr bool holds_alternative(const variant<_Types...>& __v)
+ noexcept
+ {
+ static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
+ "T should occur for exactly once in alternatives");
+ return __v.index() == __detail::__variant::__index_of_v<_Tp, _Types...>;
+ }
+
+ template<size_t _Np, typename... _Types>
+ variant_alternative_t<_Np, variant<_Types...>>&
+ get(variant<_Types...>&);
+
+ template<size_t _Np, typename... _Types>
+ variant_alternative_t<_Np, variant<_Types...>>&&
+ get(variant<_Types...>&&);
+
+ template<size_t _Np, typename... _Types>
+ variant_alternative_t<_Np, variant<_Types...>> const&
+ get(const variant<_Types...>&);
+
+ template<size_t _Np, typename... _Types>
+ variant_alternative_t<_Np, variant<_Types...>> const&&
+ get(const variant<_Types...>&&);
+
+ template<typename _Tp, typename... _Types>
+ inline _Tp& get(variant<_Types...>& __v)
+ {
+ static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
+ "T should occur for exactly once in alternatives");
+ static_assert(!is_void_v<_Tp>, "_Tp should not be void");
+ return get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v);
+ }
+
+ template<typename _Tp, typename... _Types>
+ inline _Tp&& get(variant<_Types...>&& __v)
+ {
+ static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
+ "T should occur for exactly once in alternatives");
+ static_assert(!is_void_v<_Tp>, "_Tp should not be void");
+ return get<__detail::__variant::__index_of_v<_Tp, _Types...>>(
+ std::move(__v));
+ }
+
+ template<typename _Tp, typename... _Types>
+ inline const _Tp& get(const variant<_Types...>& __v)
+ {
+ static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
+ "T should occur for exactly once in alternatives");
+ static_assert(!is_void_v<_Tp>, "_Tp should not be void");
+ return get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v);
+ }
+
+ template<typename _Tp, typename... _Types>
+ inline const _Tp&& get(const variant<_Types...>&& __v)
+ {
+ static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
+ "T should occur for exactly once in alternatives");
+ static_assert(!is_void_v<_Tp>, "_Tp should not be void");
+ return get<__detail::__variant::__index_of_v<_Tp, _Types...>>(
+ std::move(__v));
+ }
+
+ template<size_t _Np, typename... _Types>
+ inline add_pointer_t<variant_alternative_t<_Np, variant<_Types...>>>
+ get_if(variant<_Types...>* __ptr) noexcept
+ {
+ using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>;
+ static_assert(_Np < sizeof...(_Types),
+ "The index should be in [0, number of alternatives)");
+ static_assert(!is_void_v<_Alternative_type>, "_Tp should not be void");
+ if (__ptr && __ptr->index() == _Np)
+ return &__detail::__variant::__access<_Alternative_type>(*__ptr);
+ return nullptr;
+ }
+
+ template<size_t _Np, typename... _Types>
+ inline add_pointer_t<const variant_alternative_t<_Np, variant<_Types...>>>
+ get_if(const variant<_Types...>* __ptr) noexcept
+ {
+ using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>;
+ static_assert(_Np < sizeof...(_Types),
+ "The index should be in [0, number of alternatives)");
+ static_assert(!is_void_v<_Alternative_type>, "_Tp should not be void");
+ if (__ptr && __ptr->index() == _Np)
+ return &__detail::__variant::__access<_Alternative_type>(*__ptr);
+ return nullptr;
+ }
+
+ template<typename _Tp, typename... _Types>
+ inline add_pointer_t<_Tp> get_if(variant<_Types...>* __ptr) noexcept
+ {
+ static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
+ "T should occur for exactly once in alternatives");
+ static_assert(!is_void_v<_Tp>, "_Tp should not be void");
+ return get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>(__ptr);
+ }
+
+ template<typename _Tp, typename... _Types>
+ inline add_pointer_t<const _Tp> get_if(const variant<_Types...>* __ptr)
+ noexcept
+ {
+ static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>,
+ "T should occur for exactly once in alternatives");
+ static_assert(!is_void_v<_Tp>, "_Tp should not be void");
+ return get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>(__ptr);
+ }
+
+ template<typename... _Types>
+ bool operator==(const variant<_Types...>& __lhs,
+ const variant<_Types...>& __rhs)
+ {
+ if (__lhs.index() != __rhs.index())
+ return false;
+
+ if (__lhs.valueless_by_exception())
+ return true;
+
+ using __detail::__variant::__storage;
+ static constexpr bool (*_S_vtable[])(void*, void*) =
+ { &__detail::__variant::__erased_equal_to<
+ const __storage<_Types>&, const __storage<_Types>&>... };
+ return _S_vtable[__lhs.index()](
+ __detail::__variant::__get_storage(__lhs),
+ __detail::__variant::__get_storage(__rhs));
+ }
+
+ template<typename... _Types>
+ inline bool
+ operator!=(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs)
+ { return !(__lhs == __rhs); }
+
+ template<typename... _Types>
+ inline bool
+ operator<(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs)
+ {
+ if (__lhs.index() < __rhs.index())
+ return true;
+
+ if (__lhs.index() > __rhs.index())
+ return false;
+
+ if (__lhs.valueless_by_exception())
+ return false;
+
+ using __detail::__variant::__storage;
+ static constexpr bool (*_S_vtable[])(void*, void*) =
+ { &__detail::__variant::__erased_less_than<
+ const __storage<_Types>&,
+ const __storage<_Types>&>... };
+ return _S_vtable[__lhs.index()](
+ __detail::__variant::__get_storage(__lhs),
+ __detail::__variant::__get_storage(__rhs));
+ }
+
+ template<typename... _Types>
+ inline bool
+ operator>(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs)
+ { return __rhs < __lhs; }
+
+ template<typename... _Types>
+ inline bool
+ operator<=(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs)
+ { return !(__lhs > __rhs); }
+
+ template<typename... _Types>
+ inline bool
+ operator>=(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs)
+ { return !(__lhs < __rhs); }
+
+ template<typename _Visitor, typename... _Variants>
+ decltype(auto) visit(_Visitor&&, _Variants&&...);
+
+ struct monostate { };
+
+ constexpr bool operator<(monostate, monostate) noexcept
+ { return false; }
+
+ constexpr bool operator>(monostate, monostate) noexcept
+ { return false; }
+
+ constexpr bool operator<=(monostate, monostate) noexcept
+ { return true; }
+
+ constexpr bool operator>=(monostate, monostate) noexcept
+ { return true; }
+
+ constexpr bool operator==(monostate, monostate) noexcept
+ { return true; }
+
+ constexpr bool operator!=(monostate, monostate) noexcept
+ { return false; }
+
+ template<typename... _Types>
+ inline auto swap(variant<_Types...>& __lhs, variant<_Types...>& __rhs)
+ noexcept(noexcept(__lhs.swap(__rhs))) -> decltype(__lhs.swap(__rhs))
+ { __lhs.swap(__rhs); }
+
+ class bad_variant_access : public exception
+ {
+ public:
+ bad_variant_access() noexcept : _M_reason("Unknown reason") { }
+ const char* what() const noexcept override
+ { return _M_reason; }
+
+ private:
+ bad_variant_access(const char* __reason) : _M_reason(__reason) { }
+
+ const char* _M_reason;
+
+ friend void __throw_bad_variant_access(const char* __what);
+ };
+
+ inline void
+ __throw_bad_variant_access(const char* __what)
+ { _GLIBCXX_THROW_OR_ABORT(bad_variant_access(__what)); }
+
+ template<typename... _Types>
+ class variant
+ : private __detail::__variant::_Variant_base<_Types...>,
+ private _Enable_default_constructor<
+ is_default_constructible_v<
+ variant_alternative_t<0, variant<_Types...>>>, variant<_Types...>>,
+ private _Enable_copy_move<
+ __and_<is_copy_constructible<_Types>...>::value,
+ __and_<is_copy_constructible<_Types>...,
+ is_move_constructible<_Types>...,
+ is_copy_assignable<_Types>...>::value,
+ __and_<is_move_constructible<_Types>...>::value,
+ __and_<is_move_constructible<_Types>...,
+ is_move_assignable<_Types>...>::value,
+ variant<_Types...>>
+ {
+ private:
+ using _Base = __detail::__variant::_Variant_base<_Types...>;
+ using _Default_ctor_enabler =
+ _Enable_default_constructor<
+ is_default_constructible_v<
+ variant_alternative_t<0, variant<_Types...>>>, variant<_Types...>>;
+
+ template<typename _Tp>
+ static constexpr bool
+ __exactly_once = __detail::__variant::__exactly_once<_Tp, _Types...>;
+
+ template<typename _Tp>
+ static constexpr size_t __accepted_index =
+ __detail::__variant::__accepted_index<_Tp&&, variant>::value;
+
+ template<size_t _Np, bool = _Np < sizeof...(_Types)>
+ struct __to_type_impl;
+
+ template<size_t _Np>
+ struct __to_type_impl<_Np, true>
+ { using type = variant_alternative_t<_Np, variant>; };
+
+ template<size_t _Np>
+ using __to_type = typename __to_type_impl<_Np>::type;
+
+ template<typename _Tp>
+ using __accepted_type = __to_type<__accepted_index<_Tp>>;
+
+ template<typename _Tp>
+ using __storage = __detail::__variant::__storage<_Tp>;
+
+ template<typename _Tp>
+ static constexpr size_t __index_of =
+ __detail::__variant::__index_of_v<_Tp, _Types...>;
+
+ public:
+ constexpr variant()
+ noexcept(is_nothrow_default_constructible_v<__to_type<0>>) = default;
+ variant(const variant&) = default;
+ variant(variant&&)
+ noexcept(__and_<
+ is_nothrow_move_constructible<_Types>...>::value) = default;
+
+ template<typename _Tp,
+ typename = enable_if_t<__exactly_once<__accepted_type<_Tp&&>>
+ && is_constructible_v<__accepted_type<_Tp&&>, _Tp&&>
+ && !is_same_v<decay_t<_Tp>, variant>>>
+ constexpr
+ variant(_Tp&& __t)
+ noexcept(is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp&&>)
+ : variant(in_place<__accepted_index<_Tp&&>>, forward<_Tp>(__t))
+ { __glibcxx_assert(holds_alternative<__accepted_type<_Tp&&>>(*this)); }
+
+ template<typename _Tp, typename... _Args,
+ typename = enable_if_t<__exactly_once<_Tp>
+ && is_constructible_v<_Tp, _Args&&...>>>
+ constexpr explicit
+ variant(in_place_type_t<_Tp>, _Args&&... __args)
+ : variant(in_place<__index_of<_Tp>>, forward<_Args>(__args)...)
+ { __glibcxx_assert(holds_alternative<_Tp>(*this)); }
+
+ template<typename _Tp, typename _Up, typename... _Args,
+ typename = enable_if_t<__exactly_once<_Tp>
+ && is_constructible_v<
+ _Tp, initializer_list<_Up>&, _Args&&...>>>
+ constexpr explicit
+ variant(in_place_type_t<_Tp>, initializer_list<_Up> __il,
+ _Args&&... __args)
+ : variant(in_place<__index_of<_Tp>>, __il,
+ forward<_Args>(__args)...)
+ { __glibcxx_assert(holds_alternative<_Tp>(*this)); }
+
+ template<size_t _Np, typename... _Args,
+ typename = enable_if_t<
+ is_constructible_v<__to_type<_Np>, _Args&&...>>>
+ constexpr explicit
+ variant(in_place_index_t<_Np>, _Args&&... __args)
+ : _Base(in_place<_Np>, forward<_Args>(__args)...),
+ _Default_ctor_enabler(_Enable_default_constructor_tag{})
+ { __glibcxx_assert(index() == _Np); }
+
+ template<size_t _Np, typename _Up, typename... _Args,
+ typename = enable_if_t<is_constructible_v<__to_type<_Np>,
+ initializer_list<_Up>&, _Args&&...>>>
+ constexpr explicit
+ variant(in_place_index_t<_Np>, initializer_list<_Up> __il,
+ _Args&&... __args)
+ : _Base(in_place<_Np>, __il, forward<_Args>(__args)...),
+ _Default_ctor_enabler(_Enable_default_constructor_tag{})
+ { __glibcxx_assert(index() == _Np); }
+
+ template<typename _Alloc,
+ typename = enable_if_t<
+ __is_uses_allocator_constructible_v<__to_type<0>, _Alloc>>>
+ variant(allocator_arg_t, const _Alloc& __a)
+ : variant(allocator_arg, __a, in_place<0>)
+ { }
+
+ template<typename _Alloc,
+ typename = enable_if_t<__and_<__is_uses_allocator_constructible<
+ _Types, _Alloc,
+ add_lvalue_reference_t<add_const_t<_Types>>>...>::value>>
+ variant(allocator_arg_t, const _Alloc& __a, const variant& __rhs)
+ : _Base(__a, __rhs),
+ _Default_ctor_enabler(_Enable_default_constructor_tag{})
+ { }
+
+ template<typename _Alloc,
+ typename = enable_if_t<__and_<
+ __is_uses_allocator_constructible<
+ _Types, _Alloc, add_rvalue_reference_t<_Types>>...>::value>>
+ variant(allocator_arg_t, const _Alloc& __a, variant&& __rhs)
+ : _Base(__a, std::move(__rhs)),
+ _Default_ctor_enabler(_Enable_default_constructor_tag{})
+ { }
+
+ template<typename _Alloc, typename _Tp,
+ typename = enable_if_t<
+ __exactly_once<__accepted_type<_Tp&&>>
+ && __is_uses_allocator_constructible_v<
+ __accepted_type<_Tp&&>, _Alloc, _Tp&&>
+ && !is_same_v<decay_t<_Tp>, variant>, variant&>>
+ variant(allocator_arg_t, const _Alloc& __a, _Tp&& __t)
+ : variant(allocator_arg, __a, in_place<__accepted_index<_Tp&&>>,
+ forward<_Tp>(__t))
+ { __glibcxx_assert(holds_alternative<__accepted_type<_Tp&&>>(*this)); }
+
+ template<typename _Alloc, typename _Tp, typename... _Args,
+ typename = enable_if_t<
+ __exactly_once<_Tp>
+ && __is_uses_allocator_constructible_v<
+ _Tp, _Alloc, _Args&&...>>>
+ variant(allocator_arg_t, const _Alloc& __a, in_place_type_t<_Tp>,
+ _Args&&... __args)
+ : variant(allocator_arg, __a, in_place<__index_of<_Tp>>,
+ forward<_Args>(__args)...)
+ { __glibcxx_assert(holds_alternative<_Tp>(*this)); }
+
+ template<typename _Alloc, typename _Tp, typename _Up, typename... _Args,
+ typename = enable_if_t<
+ __exactly_once<_Tp>
+ && __is_uses_allocator_constructible_v<
+ _Tp, _Alloc, initializer_list<_Up>&, _Args&&...>>>
+ variant(allocator_arg_t, const _Alloc& __a, in_place_type_t<_Tp>,
+ initializer_list<_Up> __il, _Args&&... __args)
+ : variant(allocator_arg, __a, in_place<__index_of<_Tp>>, __il,
+ forward<_Args>(__args)...)
+ { __glibcxx_assert(holds_alternative<_Tp>(*this)); }
+
+ template<typename _Alloc, size_t _Np, typename... _Args,
+ typename = enable_if_t<
+ __is_uses_allocator_constructible_v<
+ __to_type<_Np>, _Alloc, _Args&&...>>>
+ variant(allocator_arg_t, const _Alloc& __a, in_place_index_t<_Np>,
+ _Args&&... __args)
+ : _Base(__a, in_place<_Np>, forward<_Args>(__args)...),
+ _Default_ctor_enabler(_Enable_default_constructor_tag{})
+ { __glibcxx_assert(index() == _Np); }
+
+ template<typename _Alloc, size_t _Np, typename _Up, typename... _Args,
+ typename = enable_if_t<
+ __is_uses_allocator_constructible_v<
+ __to_type<_Np>, _Alloc, initializer_list<_Up>&, _Args&&...>>>
+ variant(allocator_arg_t, const _Alloc& __a, in_place_index_t<_Np>,
+ initializer_list<_Up> __il, _Args&&... __args)
+ : _Base(__a, in_place<_Np>, __il, forward<_Args>(__args)...),
+ _Default_ctor_enabler(_Enable_default_constructor_tag{})
+ { __glibcxx_assert(index() == _Np); }
+
+ ~variant() = default;
+
+ variant& operator=(const variant&) = default;
+ variant& operator=(variant&&)
+ noexcept(__and_<is_nothrow_move_constructible<_Types>...,
+ is_nothrow_move_assignable<_Types>...>::value) = default;
+
+ template<typename _Tp>
+ enable_if_t<__exactly_once<__accepted_type<_Tp&&>>
+ && is_constructible_v<__accepted_type<_Tp&&>, _Tp&&>
+ && is_assignable_v<__accepted_type<_Tp&&>&, _Tp&&>
+ && !is_same_v<decay_t<_Tp>, variant>, variant&>
+ operator=(_Tp&& __rhs)
+ noexcept(is_nothrow_assignable_v<__accepted_type<_Tp&&>&, _Tp&&>
+ && is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp&&>)
+ {
+ constexpr auto __index = __accepted_index<_Tp&&>;
+ if (index() == __index)
+ *static_cast<__storage<__to_type<__index>>*>(this->_M_storage())
+ = forward<_Tp>(__rhs);
+ else
+ this->emplace<__index>(forward<_Tp>(__rhs));
+ __glibcxx_assert(holds_alternative<__accepted_type<_Tp&&>>(*this));
+ return *this;
+ }
+
+ template<typename _Tp, typename... _Args>
+ void emplace(_Args&&... __args)
+ {
+ static_assert(__exactly_once<_Tp>,
+ "T should occur for exactly once in alternatives");
+ this->emplace<__index_of<_Tp>>(forward<_Args>(__args)...);
+ __glibcxx_assert(holds_alternative<_Tp>(*this));
+ }
+
+ template<typename _Tp, typename _Up, typename... _Args>
+ void emplace(initializer_list<_Up> __il, _Args&&... __args)
+ {
+ static_assert(__exactly_once<_Tp>,
+ "T should occur for exactly once in alternatives");
+ this->emplace<__index_of<_Tp>>(__il, forward<_Args>(__args)...);
+ __glibcxx_assert(holds_alternative<_Tp>(*this));
+ }
+
+ template<size_t _Np, typename... _Args>
+ void emplace(_Args&&... __args)
+ {
+ static_assert(_Np < sizeof...(_Types),
+ "The index should be in [0, number of alternatives)");
+ this->~variant();
+ __try
+ {
+ ::new (this) variant(in_place<_Np>,
+ forward<_Args>(__args)...);
+ }
+ __catch (...)
+ {
+ this->_M_index = variant_npos;
+ __throw_exception_again;
+ }
+ __glibcxx_assert(index() == _Np);
+ }
+
+ template<size_t _Np, typename _Up, typename... _Args>
+ void emplace(initializer_list<_Up> __il, _Args&&... __args)
+ {
+ static_assert(_Np < sizeof...(_Types),
+ "The index should be in [0, number of alternatives)");
+ this->~variant();
+ __try
+ {
+ ::new (this) variant(in_place<_Np>, __il,
+ forward<_Args>(__args)...);
+ }
+ __catch (...)
+ {
+ this->_M_index = variant_npos;
+ __throw_exception_again;
+ }
+ __glibcxx_assert(index() == _Np);
+ }
+
+ constexpr bool valueless_by_exception() const noexcept
+ { return !this->_M_valid(); }
+
+ constexpr size_t index() const noexcept
+ { return this->_M_index; }
+
+ void
+ swap(variant& __rhs)
+ noexcept(__and_<__is_nothrow_swappable<_Types>...>::value
+ && is_nothrow_move_assignable_v<variant>)
+ {
+ if (this->index() == __rhs.index())
+ {
+ if (this->_M_valid())
+ {
+ static constexpr void (*_S_vtable[])(void*, void*) =
+ { &__detail::__variant::__erased_swap<
+ __storage<_Types>&, __storage<_Types>&>... };
+ _S_vtable[__rhs._M_index](this->_M_storage(),
+ __rhs._M_storage());
+ }
+ }
+ else if (!this->_M_valid())
+ {
+ *this = std::move(__rhs);
+ }
+ else if (!__rhs._M_valid())
+ {
+ __rhs = std::move(*this);
+ }
+ else
+ {
+ auto __tmp = std::move(__rhs);
+ __rhs = std::move(*this);
+ *this = std::move(__tmp);
+ }
+ }
+
+ template<typename _Vp>
+ friend void* __detail::__variant::__get_storage(_Vp&& __v);
+ };
+
+ // To honor algebraic data type, variant<> should be a bottom type, which
+ // is 0 (as opposed to a void type, which is 1). Use incomplete type to model
+ // bottom type.
+ template<> class variant<>;
+
+ template<size_t _Np, typename... _Types>
+ variant_alternative_t<_Np, variant<_Types...>>&
+ get(variant<_Types...>& __v)
+ {
+ static_assert(_Np < sizeof...(_Types),
+ "The index should be in [0, number of alternatives)");
+ if (__v.index() != _Np)
+ __throw_bad_variant_access("Unexpected index");
+ return __detail::__variant::__access<
+ variant_alternative_t<_Np, variant<_Types...>>>(__v);
+ }
+
+ template<size_t _Np, typename... _Types>
+ variant_alternative_t<_Np, variant<_Types...>>&&
+ get(variant<_Types...>&& __v)
+ {
+ static_assert(_Np < sizeof...(_Types),
+ "The index should be in [0, number of alternatives)");
+ if (__v.index() != _Np)
+ __throw_bad_variant_access("Unexpected index");
+ return __detail::__variant::__access<
+ variant_alternative_t<_Np, variant<_Types...>>>(std::move(__v));
+ }
+
+ template<size_t _Np, typename... _Types>
+ const variant_alternative_t<_Np, variant<_Types...>>&
+ get(const variant<_Types...>& __v)
+ {
+ static_assert(_Np < sizeof...(_Types),
+ "The index should be in [0, number of alternatives)");
+ if (__v.index() != _Np)
+ __throw_bad_variant_access("Unexpected index");
+ return __detail::__variant::__access<
+ variant_alternative_t<_Np, variant<_Types...>>>(__v);
+ }
+
+ template<size_t _Np, typename... _Types>
+ const variant_alternative_t<_Np, variant<_Types...>>&&
+ get(const variant<_Types...>&& __v)
+ {
+ static_assert(_Np < sizeof...(_Types),
+ "The index should be in [0, number of alternatives)");
+ if (__v.index() != _Np)
+ __throw_bad_variant_access("Unexpected index");
+ return __detail::__variant::__access<
+ variant_alternative_t<_Np, variant<_Types...>>>(std::move(__v));
+ }
+
+ template<typename _Visitor, typename... _Variants>
+ decltype(auto)
+ visit(_Visitor&& __visitor, _Variants&&... __variants)
+ {
+ using _Result_type =
+ decltype(forward<_Visitor>(__visitor)(get<0>(__variants)...));
+ static constexpr auto _S_vtable =
+ __detail::__variant::__gen_vtable<
+ _Result_type, _Visitor&&, _Variants&&...>::_S_apply();
+ auto __func_ptr = _S_vtable._M_access(__variants.index()...);
+ return (*__func_ptr)(forward<_Visitor>(__visitor),
+ __detail::__variant::__get_storage(__variants)...);
+ }
+
+ template<typename... _Types, typename _Alloc>
+ struct uses_allocator<variant<_Types...>, _Alloc>
+ : true_type { };
+
+ template<typename... _Types>
+ struct hash<variant<_Types...>>
+ {
+ using result_type = size_t;
+ using argument_type = variant<_Types...>;
+
+ size_t
+ operator()(const variant<_Types...>& __t) const
+ noexcept((... && noexcept(hash<decay_t<_Types>>{}(std::declval<_Types>()))))
+ {
+ if (!__t.valueless_by_exception())
+ {
+ namespace __edv = __detail::__variant;
+ static constexpr size_t (*_S_vtable[])(void*) =
+ { &__edv::__erased_hash<const __edv::__storage<_Types>&>... };
+ return hash<size_t>{}(__t.index())
+ + _S_vtable[__t.index()](__edv::__get_storage(__t));
+ }
+ return hash<size_t>{}(__t.index());
+ }
+ };
+
+ template<>
+ struct hash<monostate>
+ {
+ using result_type = size_t;
+ using argument_type = monostate;
+
+ size_t
+ operator()(const monostate& __t) const noexcept
+ {
+ constexpr size_t __magic_monostate_hash = -7777;
+ return __magic_monostate_hash;
+ }
+ };
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+#endif // C++17
+
+#endif // _GLIBCXX_VARIANT
diff --git a/libstdc++-v3/testsuite/20_util/variant/compile.cc b/libstdc++-v3/testsuite/20_util/variant/compile.cc
new file mode 100644
index 0000000..b57d356
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/variant/compile.cc
@@ -0,0 +1,405 @@
+// { dg-options "-std=gnu++17" }
+// { dg-do compile }
+
+// Copyright (C) 2016 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <variant>
+#include <string>
+#include <vector>
+
+using namespace std;
+
+struct AllDeleted
+{
+ AllDeleted() = delete;
+ AllDeleted(const AllDeleted&) = delete;
+ AllDeleted(AllDeleted&&) = delete;
+ AllDeleted& operator=(const AllDeleted&) = delete;
+ AllDeleted& operator=(AllDeleted&&) = delete;
+};
+
+struct Empty
+{
+ Empty() { };
+ Empty(const Empty&) { };
+ Empty(Empty&&) { };
+ Empty& operator=(const Empty&) { return *this; };
+ Empty& operator=(Empty&&) { return *this; };
+};
+
+struct DefaultNoexcept
+{
+ DefaultNoexcept() noexcept = default;
+ DefaultNoexcept(const DefaultNoexcept&) noexcept = default;
+ DefaultNoexcept(DefaultNoexcept&&) noexcept = default;
+ DefaultNoexcept& operator=(const DefaultNoexcept&) noexcept = default;
+ DefaultNoexcept& operator=(DefaultNoexcept&&) noexcept = default;
+};
+
+void default_ctor()
+{
+ static_assert(is_default_constructible_v<variant<int, string>>, "");
+ static_assert(is_default_constructible_v<variant<string, string>>, "");
+ static_assert(!is_default_constructible_v<variant<>>, "");
+ static_assert(!is_default_constructible_v<variant<AllDeleted, string>>, "");
+ static_assert(is_default_constructible_v<variant<string, AllDeleted>>, "");
+
+ static_assert(noexcept(variant<int>()), "");
+ static_assert(!noexcept(variant<Empty>()), "");
+ static_assert(noexcept(variant<DefaultNoexcept>()), "");
+}
+
+void copy_ctor()
+{
+ static_assert(is_copy_constructible_v<variant<int, string>>, "");
+ static_assert(!is_copy_constructible_v<variant<AllDeleted, string>>, "");
+
+ {
+ variant<int> a;
+ static_assert(!noexcept(variant<int>(a)), "");
+ }
+ {
+ variant<string> a;
+ static_assert(!noexcept(variant<string>(a)), "");
+ }
+ {
+ variant<int, string> a;
+ static_assert(!noexcept(variant<int, string>(a)), "");
+ }
+ {
+ variant<int, char> a;
+ static_assert(!noexcept(variant<int, char>(a)), "");
+ }
+}
+
+void move_ctor()
+{
+ static_assert(is_move_constructible_v<variant<int, string>>, "");
+ static_assert(!is_move_constructible_v<variant<AllDeleted, string>>, "");
+ static_assert(!noexcept(variant<int, Empty>(variant<int, Empty>())), "");
+ static_assert(noexcept(variant<int, DefaultNoexcept>(variant<int, DefaultNoexcept>())), "");
+}
+
+void arbitrary_ctor()
+{
+ static_assert(!is_constructible_v<variant<string, string>, const char*>, "");
+ static_assert(is_constructible_v<variant<int, string>, const char*>, "");
+ static_assert(noexcept(variant<int, Empty>(int{})), "");
+ static_assert(noexcept(variant<int, DefaultNoexcept>(int{})), "");
+ static_assert(!noexcept(variant<int, Empty>(Empty{})), "");
+ static_assert(noexcept(variant<int, DefaultNoexcept>(DefaultNoexcept{})), "");
+}
+
+void in_place_index_ctor()
+{
+ variant<string, string> a(in_place<0>, "a");
+ variant<string, string> b(in_place<1>, {'a'});
+}
+
+void in_place_type_ctor()
+{
+ variant<int, string, int> a(in_place<string>, "a");
+ variant<int, string, int> b(in_place<string>, {'a'});
+ static_assert(!is_constructible_v<variant<string, string>, in_place_type_t<string>, const char*>, "");
+}
+
+void uses_alloc_ctors()
+{
+ std::allocator<char> alloc;
+ variant<int> a(allocator_arg, alloc);
+ static_assert(!is_constructible_v<variant<AllDeleted>, allocator_arg_t, std::allocator<char>>, "");
+ {
+ variant<int> b(allocator_arg, alloc, a);
+ static_assert(!is_constructible_v<variant<void>, allocator_arg_t, std::allocator<char>, const variant<void>&>, "");
+ }
+ {
+ variant<int> b(allocator_arg, alloc, std::move(a));
+ static_assert(!is_constructible_v<variant<void>, allocator_arg_t, std::allocator<char>, variant<void>&&>, "");
+ }
+ {
+ variant<string, int> b(allocator_arg, alloc, "a");
+ static_assert(!is_constructible_v<variant<string, string>, allocator_arg_t, std::allocator<char>, const char*>, "");
+ }
+ {
+ variant<string, int> b(allocator_arg, alloc, in_place<0>, "a");
+ variant<string, string> c(allocator_arg, alloc, in_place<1>, "a");
+ }
+ {
+ variant<string, int> b(allocator_arg, alloc, in_place<0>, {'a'});
+ variant<string, string> c(allocator_arg, alloc, in_place<1>, {'a'});
+ }
+ {
+ variant<int, string, int> b(allocator_arg, alloc, in_place<string>, "a");
+ }
+ {
+ variant<int, string, int> b(allocator_arg, alloc, in_place<string>, {'a'});
+ }
+}
+
+void dtor()
+{
+ static_assert(is_destructible_v<variant<int, string>>, "");
+ static_assert(is_destructible_v<variant<AllDeleted, string>>, "");
+}
+
+void copy_assign()
+{
+ static_assert(is_copy_assignable_v<variant<int, string>>, "");
+ static_assert(!is_copy_assignable_v<variant<AllDeleted, string>>, "");
+ {
+ variant<Empty> a;
+ static_assert(!noexcept(a = a), "");
+ }
+ {
+ variant<DefaultNoexcept> a;
+ static_assert(!noexcept(a = a), "");
+ }
+}
+
+void move_assign()
+{
+ static_assert(is_move_assignable_v<variant<int, string>>, "");
+ static_assert(!is_move_assignable_v<variant<AllDeleted, string>>, "");
+ {
+ variant<Empty> a;
+ static_assert(!noexcept(a = std::move(a)), "");
+ }
+ {
+ variant<DefaultNoexcept> a;
+ static_assert(noexcept(a = std::move(a)), "");
+ }
+}
+
+void arbitrary_assign()
+{
+ static_assert(!is_assignable_v<variant<string, string>, const char*>, "");
+ static_assert(is_assignable_v<variant<int, string>, const char*>, "");
+ static_assert(noexcept(variant<int, Empty>() = int{}), "");
+ static_assert(noexcept(variant<int, DefaultNoexcept>() = int{}), "");
+ static_assert(!noexcept(variant<int, Empty>() = Empty{}), "");
+ static_assert(noexcept(variant<int, DefaultNoexcept>() = DefaultNoexcept{}), "");
+}
+
+void test_get()
+{
+ {
+ static_assert(is_same<decltype(get<0>(variant<int, string>())), int&&>::value, "");
+ static_assert(is_same<decltype(get<1>(variant<int, string>())), string&&>::value, "");
+ static_assert(is_same<decltype(get<1>(variant<int, string&>())), string&>::value, "");
+ static_assert(is_same<decltype(get<1>(variant<int, string&&>())), string&&>::value, "");
+ static_assert(is_same<decltype(get<1>(variant<int, const string>())), const string&&>::value, "");
+ static_assert(is_same<decltype(get<1>(variant<int, const string&>())), const string&>::value, "");
+ static_assert(is_same<decltype(get<1>(variant<int, const string&&>())), const string&&>::value, "");
+
+ static_assert(is_same<decltype(get<int>(variant<int, string>())), int&&>::value, "");
+ static_assert(is_same<decltype(get<string>(variant<int, string>())), string&&>::value, "");
+ static_assert(is_same<decltype(get<string&>(variant<int, string&>())), string&>::value, "");
+ static_assert(is_same<decltype(get<string&&>(variant<int, string&&>())), string&&>::value, "");
+ static_assert(is_same<decltype(get<const string>(variant<int, const string>())), const string&&>::value, "");
+ static_assert(is_same<decltype(get<const string&>(variant<int, const string&>())), const string&>::value, "");
+ static_assert(is_same<decltype(get<const string&&>(variant<int, const string&&>())), const string&&>::value, "");
+ }
+ {
+ variant<int, string> a;
+ variant<int, string&> b;
+ variant<int, string&&> c;
+ variant<int, const string> d;
+ variant<int, const string&> e;
+ variant<int, const string&&> f;
+
+ static_assert(is_same<decltype(get<0>(a)), int&>::value, "");
+ static_assert(is_same<decltype(get<1>(a)), string&>::value, "");
+ static_assert(is_same<decltype(get<1>(b)), string&>::value, "");
+ static_assert(is_same<decltype(get<1>(c)), string&>::value, "");
+ static_assert(is_same<decltype(get<1>(e)), const string&>::value, "");
+ static_assert(is_same<decltype(get<1>(e)), const string&>::value, "");
+ static_assert(is_same<decltype(get<1>(f)), const string&>::value, "");
+
+ static_assert(is_same<decltype(get<int>(a)), int&>::value, "");
+ static_assert(is_same<decltype(get<string>(a)), string&>::value, "");
+ static_assert(is_same<decltype(get<string&>(b)), string&>::value, "");
+ static_assert(is_same<decltype(get<string&&>(c)), string&>::value, "");
+ static_assert(is_same<decltype(get<const string>(e)), const string&>::value, "");
+ static_assert(is_same<decltype(get<const string&>(e)), const string&>::value, "");
+ static_assert(is_same<decltype(get<const string&&>(f)), const string&>::value, "");
+
+ static_assert(is_same<decltype(get_if<0>(&a)), int*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&a)), string*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&b)), string*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&c)), string*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&e)), const string*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&e)), const string*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&f)), const string*>::value, "");
+
+ static_assert(is_same<decltype(get_if<int>(&a)), int*>::value, "");
+ static_assert(is_same<decltype(get_if<string>(&a)), string*>::value, "");
+ static_assert(is_same<decltype(get_if<string&>(&b)), string*>::value, "");
+ static_assert(is_same<decltype(get_if<string&&>(&c)), string*>::value, "");
+ static_assert(is_same<decltype(get_if<const string>(&e)), const string*>::value, "");
+ static_assert(is_same<decltype(get_if<const string&>(&e)), const string*>::value, "");
+ static_assert(is_same<decltype(get_if<const string&&>(&f)), const string*>::value, "");
+ }
+ {
+ const variant<int, string> a;
+ const variant<int, string&> b;
+ const variant<int, string&&> c;
+ const variant<int, const string> d;
+ const variant<int, const string&> e;
+ const variant<int, const string&&> f;
+
+ static_assert(is_same<decltype(get<0>(a)), const int&>::value, "");
+ static_assert(is_same<decltype(get<1>(a)), const string&>::value, "");
+ static_assert(is_same<decltype(get<1>(b)), string&>::value, "");
+ static_assert(is_same<decltype(get<1>(c)), string&>::value, "");
+ static_assert(is_same<decltype(get<1>(d)), const string&>::value, "");
+ static_assert(is_same<decltype(get<1>(e)), const string&>::value, "");
+ static_assert(is_same<decltype(get<1>(f)), const string&>::value, "");
+
+ static_assert(is_same<decltype(get<int>(a)), const int&>::value, "");
+ static_assert(is_same<decltype(get<string>(a)), const string&>::value, "");
+ static_assert(is_same<decltype(get<string&>(b)), string&>::value, "");
+ static_assert(is_same<decltype(get<string&&>(c)), string&>::value, "");
+ static_assert(is_same<decltype(get<const string>(d)), const string&>::value, "");
+ static_assert(is_same<decltype(get<const string&>(e)), const string&>::value, "");
+ static_assert(is_same<decltype(get<const string&&>(f)), const string&>::value, "");
+
+ static_assert(is_same<decltype(get_if<0>(&a)), const int*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&a)), const string*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&b)), string*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&c)), string*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&d)), const string*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&e)), const string*>::value, "");
+ static_assert(is_same<decltype(get_if<1>(&f)), const string*>::value, "");
+
+ static_assert(is_same<decltype(get_if<int>(&a)), const int*>::value, "");
+ static_assert(is_same<decltype(get_if<string>(&a)), const string*>::value, "");
+ static_assert(is_same<decltype(get_if<string&>(&b)), string*>::value, "");
+ static_assert(is_same<decltype(get_if<string&&>(&c)), string*>::value, "");
+ static_assert(is_same<decltype(get_if<const string>(&d)), const string*>::value, "");
+ static_assert(is_same<decltype(get_if<const string&>(&e)), const string*>::value, "");
+ static_assert(is_same<decltype(get_if<const string&&>(&f)), const string*>::value, "");
+ }
+}
+
+void test_relational()
+{
+ {
+ const variant<int, string> a, b;
+ (void)(a < b);
+ (void)(a > b);
+ (void)(a <= b);
+ (void)(a == b);
+ (void)(a != b);
+ (void)(a >= b);
+ }
+ {
+ const monostate a, b;
+ (void)(a < b);
+ (void)(a > b);
+ (void)(a <= b);
+ (void)(a == b);
+ (void)(a != b);
+ (void)(a >= b);
+ }
+}
+
+void test_swap()
+{
+ variant<int, string> a, b;
+ a.swap(b);
+ swap(a, b);
+}
+
+void test_visit()
+{
+ {
+ struct Visitor
+ {
+ void operator()(monostate) {}
+ void operator()(const int&) {}
+ };
+ struct CVisitor
+ {
+ void operator()(monostate) const {}
+ void operator()(const int&) const {}
+ };
+ variant<monostate, int&, const int&, int&&, const int&&> a;
+ const variant<monostate, int&, const int&, int&&, const int&&> b;
+ Visitor v;
+ const CVisitor u;
+ static_assert(is_same<void, decltype(visit(Visitor(), a))>::value, "");
+ static_assert(is_same<void, decltype(visit(Visitor(), b))>::value, "");
+ static_assert(is_same<void, decltype(visit(v, a))>::value, "");
+ static_assert(is_same<void, decltype(visit(v, b))>::value, "");
+ static_assert(is_same<void, decltype(visit(u, a))>::value, "");
+ static_assert(is_same<void, decltype(visit(u, b))>::value, "");
+ }
+ {
+ struct Visitor
+ {
+ bool operator()(int, float) { return false; }
+ bool operator()(int, double) { return false; }
+ bool operator()(char, float) { return false; }
+ bool operator()(char, double) { return false; }
+ };
+ visit(Visitor(), variant<int, char>(), variant<float, double>());
+ }
+}
+
+void test_constexpr()
+{
+ constexpr variant<int> a;
+ static_assert(holds_alternative<int>(a), "");
+ constexpr variant<int, char> b(in_place<0>, int{});
+ static_assert(holds_alternative<int>(b), "");
+ constexpr variant<int, char> c(in_place<int>, int{});
+ static_assert(holds_alternative<int>(c), "");
+ constexpr variant<int, char> d(in_place<1>, char{});
+ static_assert(holds_alternative<char>(d), "");
+ constexpr variant<int, char> e(in_place<char>, char{});
+ static_assert(holds_alternative<char>(e), "");
+ constexpr variant<int, char> f(char{});
+ static_assert(holds_alternative<char>(f), "");
+
+ {
+ struct literal {
+ constexpr literal() = default;
+ };
+
+ struct nonliteral {
+ nonliteral() { }
+ };
+
+ constexpr variant<literal, nonliteral> v{};
+ constexpr variant<literal, nonliteral> v1{in_place<literal>};
+ constexpr variant<literal, nonliteral> v2{in_place<0>};
+ }
+}
+
+void test_void()
+{
+ static_assert(is_same<int&&, decltype(get<int>(variant<int, void>()))>::value, "");
+ static_assert(!is_default_constructible_v<variant<void, int>>, "");
+ static_assert(!is_copy_constructible_v<variant<int, void>>, "");
+ static_assert(!is_move_constructible_v<variant<int, void>>, "");
+ static_assert(!is_copy_assignable_v<variant<int, void>>, "");
+ static_assert(!is_move_assignable_v<variant<int, void>>, "");
+ variant<int, void, string> v;
+ v = 3;
+ v = "asdf";
+}
diff --git a/libstdc++-v3/testsuite/20_util/variant/run.cc b/libstdc++-v3/testsuite/20_util/variant/run.cc
new file mode 100644
index 0000000..cbe3b17
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/variant/run.cc
@@ -0,0 +1,501 @@
+// { dg-options "-std=gnu++17" }
+// { dg-do run }
+
+// Copyright (C) 2016 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <variant>
+#include <string>
+#include <vector>
+#include <unordered_set>
+#include <testsuite_hooks.h>
+
+using namespace std;
+
+struct AlwaysThrow
+{
+ AlwaysThrow() = default;
+
+ AlwaysThrow(const AlwaysThrow&)
+ { throw nullptr; }
+
+ AlwaysThrow(AlwaysThrow&&)
+ { throw nullptr; }
+
+ AlwaysThrow& operator=(const AlwaysThrow&)
+ {
+ throw nullptr;
+ return *this;
+ }
+
+ AlwaysThrow& operator=(AlwaysThrow&&)
+ {
+ throw nullptr;
+ return *this;
+ }
+};
+
+void default_ctor()
+{
+ bool test [[gnu::unused]] = true;
+
+ variant<monostate, string> v;
+ VERIFY(holds_alternative<monostate>(v));
+}
+
+void copy_ctor()
+{
+ bool test [[gnu::unused]] = true;
+
+ variant<monostate, string> v("a");
+ VERIFY(holds_alternative<string>(v));
+ variant<monostate, string> u(v);
+ VERIFY(holds_alternative<string>(u));
+ VERIFY(get<string>(u) == "a");
+}
+
+void move_ctor()
+{
+ bool test [[gnu::unused]] = true;
+
+ variant<monostate, string> v("a");
+ VERIFY(holds_alternative<string>(v));
+ variant<monostate, string> u(std::move(v));
+ VERIFY(holds_alternative<string>(u));
+ VERIFY(get<string>(u) == "a");
+ VERIFY(holds_alternative<string>(v));
+}
+
+void arbitrary_ctor()
+{
+ bool test [[gnu::unused]] = true;
+
+ variant<int, string> v("a");
+ VERIFY(holds_alternative<string>(v));
+ VERIFY(get<1>(v) == "a");
+}
+
+void copy_assign()
+{
+ bool test [[gnu::unused]] = true;
+
+ variant<monostate, string> v("a");
+ VERIFY(holds_alternative<string>(v));
+ variant<monostate, string> u;
+ u = v;
+ VERIFY(holds_alternative<string>(u));
+ VERIFY(get<string>(u) == "a");
+}
+
+void move_assign()
+{
+ bool test [[gnu::unused]] = true;
+
+ variant<monostate, string> v("a");
+ VERIFY(holds_alternative<string>(v));
+ variant<monostate, string> u;
+ u = std::move(v);
+ VERIFY(holds_alternative<string>(u));
+ VERIFY(get<string>(u) == "a");
+ VERIFY(holds_alternative<string>(v));
+}
+
+void arbitrary_assign()
+{
+ bool test [[gnu::unused]] = true;
+
+ variant<int, string> v;
+ v = "a";
+
+ VERIFY(holds_alternative<string>(variant<int, string>("a")));
+ VERIFY(get<1>(v) == "a");
+}
+
+void dtor()
+{
+ bool test [[gnu::unused]] = true;
+
+ struct A {
+ A(int& called) : called(called) {}
+ ~A() {
+ called++;
+ }
+ int& called;
+ };
+ {
+ int called = 0;
+ { variant<string, A> a(in_place<1>, called); }
+ VERIFY(called == 1);
+ }
+ {
+ int called = 0;
+ { variant<string, A> a(in_place<0>); }
+ VERIFY(called == 0);
+ }
+}
+
+void in_place_index_ctor()
+{
+ bool test [[gnu::unused]] = true;
+
+ {
+ variant<int, string> v(in_place<1>, "a");
+ VERIFY(holds_alternative<string>(v));
+ VERIFY(get<1>(v) == "a");
+ }
+ {
+ variant<int, string> v(in_place<1>, {'a', 'b'});
+ VERIFY(holds_alternative<string>(v));
+ VERIFY(get<1>(v) == "ab");
+ }
+}
+
+void in_place_type_ctor()
+{
+ bool test [[gnu::unused]] = true;
+
+ {
+ variant<int, string> v(in_place<string>, "a");
+ VERIFY(holds_alternative<string>(v));
+ VERIFY(get<1>(v) == "a");
+ }
+ {
+ variant<int, string> v(in_place<string>, {'a', 'b'});
+ VERIFY(holds_alternative<string>(v));
+ VERIFY(get<1>(v) == "ab");
+ }
+}
+
+struct UsesAllocatable
+{
+ template<typename Alloc>
+ UsesAllocatable(std::allocator_arg_t, const Alloc& a)
+ : d(0), a(static_cast<const void*>(&a)) { }
+
+ template<typename Alloc>
+ UsesAllocatable(std::allocator_arg_t, const Alloc& a, const UsesAllocatable&)
+ : d(1), a(static_cast<const void*>(&a)) { }
+
+ template<typename Alloc>
+ UsesAllocatable(std::allocator_arg_t, const Alloc& a, UsesAllocatable&&)
+ : d(2), a(static_cast<const void*>(&a)) { }
+
+ int d;
+ const void* a;
+};
+
+namespace std
+{
+ template<>
+ struct uses_allocator<UsesAllocatable, std::allocator<char>> : true_type { };
+}
+
+void uses_allocator_ctor()
+{
+ bool test [[gnu::unused]] = true;
+
+ std::allocator<char> a;
+ variant<UsesAllocatable> v(std::allocator_arg, a);
+ VERIFY(get<0>(v).d == 0);
+ VERIFY(get<0>(v).a == &a);
+ {
+ variant<UsesAllocatable> u(std::allocator_arg, a, v);
+ VERIFY(get<0>(u).d == 1);
+ VERIFY(get<0>(u).a == &a);
+ }
+ {
+ variant<UsesAllocatable> u(std::allocator_arg, a, std::move(v));
+ VERIFY(get<0>(u).d == 2);
+ VERIFY(get<0>(u).a == &a);
+ }
+}
+
+void emplace()
+{
+ bool test [[gnu::unused]] = true;
+
+ variant<int, string> v;
+ v.emplace<0>(1);
+ VERIFY(get<0>(v) == 1);
+ v.emplace<string>("a");
+ VERIFY(get<string>(v) == "a");
+ v.emplace<1>({'a', 'b'});
+ VERIFY(get<1>(v) == "ab");
+ v.emplace<string>({'a', 'c'});
+ VERIFY(get<string>(v) == "ac");
+ {
+ variant<int, AlwaysThrow> v;
+ AlwaysThrow a;
+ try { v.emplace<1>(a); } catch (nullptr_t) { }
+ VERIFY(v.valueless_by_exception());
+ }
+ {
+ variant<int, AlwaysThrow> v;
+ try { v.emplace<1>(AlwaysThrow{}); } catch (nullptr_t) { }
+ VERIFY(v.valueless_by_exception());
+ }
+}
+
+void test_get()
+{
+ bool test [[gnu::unused]] = true;
+
+ VERIFY(get<1>(variant<int, string>("a")) == "a");
+ VERIFY(get<string>(variant<int, string>("a")) == "a");
+ {
+ bool caught = false;
+
+ try
+ {
+ get<0>(variant<int, string>("a"));
+ }
+ catch (const bad_variant_access&)
+ {
+ caught = true;
+ }
+ VERIFY(caught);
+ }
+ {
+ bool caught = false;
+
+ try
+ {
+ get<int>(variant<int, string>("a"));
+ }
+ catch (const bad_variant_access&)
+ {
+ caught = true;
+ }
+ VERIFY(caught);
+ }
+}
+
+void test_relational()
+{
+ bool test [[gnu::unused]] = true;
+
+ VERIFY((variant<int, string>(2) < variant<int, string>(3)));
+ VERIFY((variant<int, string>(3) == variant<int, string>(3)));
+ VERIFY((variant<int, string>(3) > variant<int, string>(2)));
+ VERIFY((variant<int, string>(3) <= variant<int, string>(3)));
+ VERIFY((variant<int, string>(2) <= variant<int, string>(3)));
+ VERIFY((variant<int, string>(3) >= variant<int, string>(3)));
+ VERIFY((variant<int, string>(3) >= variant<int, string>(2)));
+ VERIFY((variant<int, string>(2) != variant<int, string>(3)));
+
+ VERIFY((variant<int, string>(2) < variant<int, string>("a")));
+ VERIFY((variant<string, int>(2) > variant<string, int>("a")));
+}
+
+void test_swap()
+{
+ bool test [[gnu::unused]] = true;
+
+ variant<int, string> a("a"), b("b");
+ a.swap(b);
+ VERIFY(get<1>(a) == "b");
+ VERIFY(get<1>(b) == "a");
+ swap(a, b);
+ VERIFY(get<1>(a) == "a");
+ VERIFY(get<1>(b) == "b");
+}
+
+void test_visit()
+{
+ bool test [[gnu::unused]] = true;
+
+ {
+ struct Visitor
+ {
+ int operator()(int, float) {
+ return 0;
+ }
+ int operator()(int, double) {
+ return 1;
+ }
+ int operator()(char, float) {
+ return 2;
+ }
+ int operator()(char, double) {
+ return 3;
+ }
+ int operator()(int, float) const {
+ return 5;
+ }
+ int operator()(int, double) const {
+ return 6;
+ }
+ int operator()(char, float) const {
+ return 7;
+ }
+ int operator()(char, double) const {
+ return 8;
+ }
+ } visitor1;
+ VERIFY(visit(visitor1, variant<int, char>(1), variant<float, double>(1.0f)) == 0);
+ VERIFY(visit(visitor1, variant<int, char>(1), variant<float, double>(1.0)) == 1);
+ VERIFY(visit(visitor1, variant<int, char>('a'), variant<float, double>(1.0f)) == 2);
+ VERIFY(visit(visitor1, variant<int, char>('a'), variant<float, double>(1.0)) == 3);
+
+ const auto& visitor2 = visitor1;
+ VERIFY(visit(visitor2, variant<int, char>(1), variant<float, double>(1.0f)) == 5);
+ VERIFY(visit(visitor2, variant<int, char>(1), variant<float, double>(1.0)) == 6);
+ VERIFY(visit(visitor2, variant<int, char>('a'), variant<float, double>(1.0f)) == 7);
+ VERIFY(visit(visitor2, variant<int, char>('a'), variant<float, double>(1.0)) == 8);
+ }
+
+ {
+ struct Visitor
+ {
+ int operator()(int, float) && {
+ return 0;
+ }
+ int operator()(int, double) && {
+ return 1;
+ }
+ int operator()(char, float) && {
+ return 2;
+ }
+ int operator()(char, double) && {
+ return 3;
+ }
+ };
+ VERIFY(visit(Visitor{}, variant<int, char>(1), variant<float, double>(1.0f)) == 0);
+ VERIFY(visit(Visitor{}, variant<int, char>(1), variant<float, double>(1.0)) == 1);
+ VERIFY(visit(Visitor{}, variant<int, char>('a'), variant<float, double>(1.0f)) == 2);
+ VERIFY(visit(Visitor{}, variant<int, char>('a'), variant<float, double>(1.0)) == 3);
+ }
+}
+
+void test_hash()
+{
+ bool test [[gnu::unused]] = true;
+
+ unordered_set<variant<int, string>> s;
+ VERIFY(s.emplace(3).second);
+ VERIFY(s.emplace("asdf").second);
+ VERIFY(s.emplace().second);
+ VERIFY(s.size() == 3);
+ VERIFY(!s.emplace(3).second);
+ VERIFY(!s.emplace("asdf").second);
+ VERIFY(!s.emplace().second);
+ VERIFY(s.size() == 3);
+ {
+ struct A
+ {
+ operator int()
+ {
+ throw nullptr;
+ }
+ };
+ variant<int, string> v;
+ try
+ {
+ v.emplace<0>(A{});
+ }
+ catch (nullptr_t)
+ {
+ }
+ VERIFY(v.valueless_by_exception());
+ VERIFY(s.insert(v).second);
+ VERIFY(s.size() == 4);
+ VERIFY(!s.insert(v).second);
+ }
+}
+
+void test_valueless_by_exception()
+{
+ bool test [[gnu::unused]] = true;
+
+ {
+ AlwaysThrow a;
+ bool caught = false;
+ try
+ {
+ variant<int, AlwaysThrow> v(a);
+ }
+ catch (nullptr_t)
+ {
+ caught = true;
+ }
+ VERIFY(caught);
+ }
+ {
+ AlwaysThrow a;
+ bool caught = false;
+ try
+ {
+ variant<int, AlwaysThrow> v(a);
+ }
+ catch (nullptr_t)
+ {
+ caught = true;
+ }
+ VERIFY(caught);
+ }
+ {
+ variant<int, AlwaysThrow> v;
+ bool caught = false;
+ try
+ {
+ AlwaysThrow a;
+ v = a;
+ }
+ catch (nullptr_t)
+ {
+ caught = true;
+ }
+ VERIFY(caught);
+ VERIFY(v.valueless_by_exception());
+ }
+ {
+ variant<int, AlwaysThrow> v;
+ bool caught = false;
+ try
+ {
+ v = AlwaysThrow{};
+ }
+ catch (nullptr_t)
+ {
+ caught = true;
+ }
+ VERIFY(caught);
+ VERIFY(v.valueless_by_exception());
+ }
+}
+
+int main()
+{
+ default_ctor();
+ copy_ctor();
+ move_ctor();
+ arbitrary_ctor();
+ in_place_index_ctor();
+ in_place_type_ctor();
+ uses_allocator_ctor();
+ copy_assign();
+ move_assign();
+ arbitrary_assign();
+ dtor();
+ emplace();
+ test_get();
+ test_relational();
+ test_swap();
+ test_visit();
+ test_hash();
+ test_valueless_by_exception();
+}
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