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Diffstat (limited to 'third_party/abseil_cpp/absl/types/variant.h')
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diff --git a/third_party/abseil_cpp/absl/types/variant.h b/third_party/abseil_cpp/absl/types/variant.h deleted file mode 100644 index 776d19a1c5..0000000000 --- a/third_party/abseil_cpp/absl/types/variant.h +++ /dev/null @@ -1,861 +0,0 @@ -// Copyright 2018 The Abseil Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. -// -// ----------------------------------------------------------------------------- -// variant.h -// ----------------------------------------------------------------------------- -// -// This header file defines an `absl::variant` type for holding a type-safe -// value of some prescribed set of types (noted as alternative types), and -// associated functions for managing variants. -// -// The `absl::variant` type is a form of type-safe union. An `absl::variant` -// should always hold a value of one of its alternative types (except in the -// "valueless by exception state" -- see below). A default-constructed -// `absl::variant` will hold the value of its first alternative type, provided -// it is default-constructible. -// -// In exceptional cases due to error, an `absl::variant` can hold no -// value (known as a "valueless by exception" state), though this is not the -// norm. -// -// As with `absl::optional`, an `absl::variant` -- when it holds a value -- -// allocates a value of that type directly within the `variant` itself; it -// cannot hold a reference, array, or the type `void`; it can, however, hold a -// pointer to externally managed memory. -// -// `absl::variant` is a C++11 compatible version of the C++17 `std::variant` -// abstraction and is designed to be a drop-in replacement for code compliant -// with C++17. - -#ifndef ABSL_TYPES_VARIANT_H_ -#define ABSL_TYPES_VARIANT_H_ - -#include "absl/base/config.h" -#include "absl/utility/utility.h" - -#ifdef ABSL_USES_STD_VARIANT - -#include <variant> // IWYU pragma: export - -namespace absl { -ABSL_NAMESPACE_BEGIN -using std::bad_variant_access; -using std::get; -using std::get_if; -using std::holds_alternative; -using std::monostate; -using std::variant; -using std::variant_alternative; -using std::variant_alternative_t; -using std::variant_npos; -using std::variant_size; -using std::variant_size_v; -using std::visit; -ABSL_NAMESPACE_END -} // namespace absl - -#else // ABSL_USES_STD_VARIANT - -#include <functional> -#include <new> -#include <type_traits> -#include <utility> - -#include "absl/base/macros.h" -#include "absl/base/port.h" -#include "absl/meta/type_traits.h" -#include "absl/types/internal/variant.h" - -namespace absl { -ABSL_NAMESPACE_BEGIN - -// ----------------------------------------------------------------------------- -// absl::variant -// ----------------------------------------------------------------------------- -// -// An `absl::variant` type is a form of type-safe union. An `absl::variant` -- -// except in exceptional cases -- always holds a value of one of its alternative -// types. -// -// Example: -// -// // Construct a variant that holds either an integer or a std::string and -// // assign it to a std::string. -// absl::variant<int, std::string> v = std::string("abc"); -// -// // A default-constructed variant will hold a value-initialized value of -// // the first alternative type. -// auto a = absl::variant<int, std::string>(); // Holds an int of value '0'. -// -// // variants are assignable. -// -// // copy assignment -// auto v1 = absl::variant<int, std::string>("abc"); -// auto v2 = absl::variant<int, std::string>(10); -// v2 = v1; // copy assign -// -// // move assignment -// auto v1 = absl::variant<int, std::string>("abc"); -// v1 = absl::variant<int, std::string>(10); -// -// // assignment through type conversion -// a = 128; // variant contains int -// a = "128"; // variant contains std::string -// -// An `absl::variant` holding a value of one of its alternative types `T` holds -// an allocation of `T` directly within the variant itself. An `absl::variant` -// is not allowed to allocate additional storage, such as dynamic memory, to -// allocate the contained value. The contained value shall be allocated in a -// region of the variant storage suitably aligned for all alternative types. -template <typename... Ts> -class variant; - -// swap() -// -// Swaps two `absl::variant` values. This function is equivalent to `v.swap(w)` -// where `v` and `w` are `absl::variant` types. -// -// Note that this function requires all alternative types to be both swappable -// and move-constructible, because any two variants may refer to either the same -// type (in which case, they will be swapped) or to two different types (in -// which case the values will need to be moved). -// -template < - typename... Ts, - absl::enable_if_t< - absl::conjunction<std::is_move_constructible<Ts>..., - type_traits_internal::IsSwappable<Ts>...>::value, - int> = 0> -void swap(variant<Ts...>& v, variant<Ts...>& w) noexcept(noexcept(v.swap(w))) { - v.swap(w); -} - -// variant_size -// -// Returns the number of alternative types available for a given `absl::variant` -// type as a compile-time constant expression. As this is a class template, it -// is not generally useful for accessing the number of alternative types of -// any given `absl::variant` instance. -// -// Example: -// -// auto a = absl::variant<int, std::string>; -// constexpr int num_types = -// absl::variant_size<absl::variant<int, std::string>>(); -// -// // You can also use the member constant `value`. -// constexpr int num_types = -// absl::variant_size<absl::variant<int, std::string>>::value; -// -// // `absl::variant_size` is more valuable for use in generic code: -// template <typename Variant> -// constexpr bool IsVariantMultivalue() { -// return absl::variant_size<Variant>() > 1; -// } -// -// Note that the set of cv-qualified specializations of `variant_size` are -// provided to ensure that those specializations compile (especially when passed -// within template logic). -template <class T> -struct variant_size; - -template <class... Ts> -struct variant_size<variant<Ts...>> - : std::integral_constant<std::size_t, sizeof...(Ts)> {}; - -// Specialization of `variant_size` for const qualified variants. -template <class T> -struct variant_size<const T> : variant_size<T>::type {}; - -// Specialization of `variant_size` for volatile qualified variants. -template <class T> -struct variant_size<volatile T> : variant_size<T>::type {}; - -// Specialization of `variant_size` for const volatile qualified variants. -template <class T> -struct variant_size<const volatile T> : variant_size<T>::type {}; - -// variant_alternative -// -// Returns the alternative type for a given `absl::variant` at the passed -// index value as a compile-time constant expression. As this is a class -// template resulting in a type, it is not useful for access of the run-time -// value of any given `absl::variant` variable. -// -// Example: -// -// // The type of the 0th alternative is "int". -// using alternative_type_0 -// = absl::variant_alternative<0, absl::variant<int, std::string>>::type; -// -// static_assert(std::is_same<alternative_type_0, int>::value, ""); -// -// // `absl::variant_alternative` is more valuable for use in generic code: -// template <typename Variant> -// constexpr bool IsFirstElementTrivial() { -// return std::is_trivial_v<variant_alternative<0, Variant>::type>; -// } -// -// Note that the set of cv-qualified specializations of `variant_alternative` -// are provided to ensure that those specializations compile (especially when -// passed within template logic). -template <std::size_t I, class T> -struct variant_alternative; - -template <std::size_t I, class... Types> -struct variant_alternative<I, variant<Types...>> { - using type = - variant_internal::VariantAlternativeSfinaeT<I, variant<Types...>>; -}; - -// Specialization of `variant_alternative` for const qualified variants. -template <std::size_t I, class T> -struct variant_alternative<I, const T> { - using type = const typename variant_alternative<I, T>::type; -}; - -// Specialization of `variant_alternative` for volatile qualified variants. -template <std::size_t I, class T> -struct variant_alternative<I, volatile T> { - using type = volatile typename variant_alternative<I, T>::type; -}; - -// Specialization of `variant_alternative` for const volatile qualified -// variants. -template <std::size_t I, class T> -struct variant_alternative<I, const volatile T> { - using type = const volatile typename variant_alternative<I, T>::type; -}; - -// Template type alias for variant_alternative<I, T>::type. -// -// Example: -// -// using alternative_type_0 -// = absl::variant_alternative_t<0, absl::variant<int, std::string>>; -// static_assert(std::is_same<alternative_type_0, int>::value, ""); -template <std::size_t I, class T> -using variant_alternative_t = typename variant_alternative<I, T>::type; - -// holds_alternative() -// -// Checks whether the given variant currently holds a given alternative type, -// returning `true` if so. -// -// Example: -// -// absl::variant<int, std::string> foo = 42; -// if (absl::holds_alternative<int>(foo)) { -// std::cout << "The variant holds an integer"; -// } -template <class T, class... Types> -constexpr bool holds_alternative(const variant<Types...>& v) noexcept { - static_assert( - variant_internal::UnambiguousIndexOfImpl<variant<Types...>, T, - 0>::value != sizeof...(Types), - "The type T must occur exactly once in Types..."); - return v.index() == - variant_internal::UnambiguousIndexOf<variant<Types...>, T>::value; -} - -// get() -// -// Returns a reference to the value currently within a given variant, using -// either a unique alternative type amongst the variant's set of alternative -// types, or the variant's index value. Attempting to get a variant's value -// using a type that is not unique within the variant's set of alternative types -// is a compile-time error. If the index of the alternative being specified is -// different from the index of the alternative that is currently stored, throws -// `absl::bad_variant_access`. -// -// Example: -// -// auto a = absl::variant<int, std::string>; -// -// // Get the value by type (if unique). -// int i = absl::get<int>(a); -// -// auto b = absl::variant<int, int>; -// -// // Getting the value by a type that is not unique is ill-formed. -// int j = absl::get<int>(b); // Compile Error! -// -// // Getting value by index not ambiguous and allowed. -// int k = absl::get<1>(b); - -// Overload for getting a variant's lvalue by type. -template <class T, class... Types> -constexpr T& get(variant<Types...>& v) { // NOLINT - return variant_internal::VariantCoreAccess::CheckedAccess< - variant_internal::IndexOf<T, Types...>::value>(v); -} - -// Overload for getting a variant's rvalue by type. -// Note: `absl::move()` is required to allow use of constexpr in C++11. -template <class T, class... Types> -constexpr T&& get(variant<Types...>&& v) { - return variant_internal::VariantCoreAccess::CheckedAccess< - variant_internal::IndexOf<T, Types...>::value>(absl::move(v)); -} - -// Overload for getting a variant's const lvalue by type. -template <class T, class... Types> -constexpr const T& get(const variant<Types...>& v) { - return variant_internal::VariantCoreAccess::CheckedAccess< - variant_internal::IndexOf<T, Types...>::value>(v); -} - -// Overload for getting a variant's const rvalue by type. -// Note: `absl::move()` is required to allow use of constexpr in C++11. -template <class T, class... Types> -constexpr const T&& get(const variant<Types...>&& v) { - return variant_internal::VariantCoreAccess::CheckedAccess< - variant_internal::IndexOf<T, Types...>::value>(absl::move(v)); -} - -// Overload for getting a variant's lvalue by index. -template <std::size_t I, class... Types> -constexpr variant_alternative_t<I, variant<Types...>>& get( - variant<Types...>& v) { // NOLINT - return variant_internal::VariantCoreAccess::CheckedAccess<I>(v); -} - -// Overload for getting a variant's rvalue by index. -// Note: `absl::move()` is required to allow use of constexpr in C++11. -template <std::size_t I, class... Types> -constexpr variant_alternative_t<I, variant<Types...>>&& get( - variant<Types...>&& v) { - return variant_internal::VariantCoreAccess::CheckedAccess<I>(absl::move(v)); -} - -// Overload for getting a variant's const lvalue by index. -template <std::size_t I, class... Types> -constexpr const variant_alternative_t<I, variant<Types...>>& get( - const variant<Types...>& v) { - return variant_internal::VariantCoreAccess::CheckedAccess<I>(v); -} - -// Overload for getting a variant's const rvalue by index. -// Note: `absl::move()` is required to allow use of constexpr in C++11. -template <std::size_t I, class... Types> -constexpr const variant_alternative_t<I, variant<Types...>>&& get( - const variant<Types...>&& v) { - return variant_internal::VariantCoreAccess::CheckedAccess<I>(absl::move(v)); -} - -// get_if() -// -// Returns a pointer to the value currently stored within a given variant, if -// present, using either a unique alternative type amongst the variant's set of -// alternative types, or the variant's index value. If such a value does not -// exist, returns `nullptr`. -// -// As with `get`, attempting to get a variant's value using a type that is not -// unique within the variant's set of alternative types is a compile-time error. - -// Overload for getting a pointer to the value stored in the given variant by -// index. -template <std::size_t I, class... Types> -constexpr absl::add_pointer_t<variant_alternative_t<I, variant<Types...>>> -get_if(variant<Types...>* v) noexcept { - return (v != nullptr && v->index() == I) - ? std::addressof( - variant_internal::VariantCoreAccess::Access<I>(*v)) - : nullptr; -} - -// Overload for getting a pointer to the const value stored in the given -// variant by index. -template <std::size_t I, class... Types> -constexpr absl::add_pointer_t<const variant_alternative_t<I, variant<Types...>>> -get_if(const variant<Types...>* v) noexcept { - return (v != nullptr && v->index() == I) - ? std::addressof( - variant_internal::VariantCoreAccess::Access<I>(*v)) - : nullptr; -} - -// Overload for getting a pointer to the value stored in the given variant by -// type. -template <class T, class... Types> -constexpr absl::add_pointer_t<T> get_if(variant<Types...>* v) noexcept { - return absl::get_if<variant_internal::IndexOf<T, Types...>::value>(v); -} - -// Overload for getting a pointer to the const value stored in the given variant -// by type. -template <class T, class... Types> -constexpr absl::add_pointer_t<const T> get_if( - const variant<Types...>* v) noexcept { - return absl::get_if<variant_internal::IndexOf<T, Types...>::value>(v); -} - -// visit() -// -// Calls a provided functor on a given set of variants. `absl::visit()` is -// commonly used to conditionally inspect the state of a given variant (or set -// of variants). -// -// The functor must return the same type when called with any of the variants' -// alternatives. -// -// Example: -// -// // Define a visitor functor -// struct GetVariant { -// template<typename T> -// void operator()(const T& i) const { -// std::cout << "The variant's value is: " << i; -// } -// }; -// -// // Declare our variant, and call `absl::visit()` on it. -// // Note that `GetVariant()` returns void in either case. -// absl::variant<int, std::string> foo = std::string("foo"); -// GetVariant visitor; -// absl::visit(visitor, foo); // Prints `The variant's value is: foo' -template <typename Visitor, typename... Variants> -variant_internal::VisitResult<Visitor, Variants...> visit(Visitor&& vis, - Variants&&... vars) { - return variant_internal:: - VisitIndices<variant_size<absl::decay_t<Variants> >::value...>::Run( - variant_internal::PerformVisitation<Visitor, Variants...>{ - std::forward_as_tuple(absl::forward<Variants>(vars)...), - absl::forward<Visitor>(vis)}, - vars.index()...); -} - -// monostate -// -// The monostate class serves as a first alternative type for a variant for -// which the first variant type is otherwise not default-constructible. -struct monostate {}; - -// `absl::monostate` Relational Operators - -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; } - - -//------------------------------------------------------------------------------ -// `absl::variant` Template Definition -//------------------------------------------------------------------------------ -template <typename T0, typename... Tn> -class variant<T0, Tn...> : private variant_internal::VariantBase<T0, Tn...> { - static_assert(absl::conjunction<std::is_object<T0>, - std::is_object<Tn>...>::value, - "Attempted to instantiate a variant containing a non-object " - "type."); - // Intentionally not qualifying `negation` with `absl::` to work around a bug - // in MSVC 2015 with inline namespace and variadic template. - static_assert(absl::conjunction<negation<std::is_array<T0> >, - negation<std::is_array<Tn> >...>::value, - "Attempted to instantiate a variant containing an array type."); - static_assert(absl::conjunction<std::is_nothrow_destructible<T0>, - std::is_nothrow_destructible<Tn>...>::value, - "Attempted to instantiate a variant containing a non-nothrow " - "destructible type."); - - friend struct variant_internal::VariantCoreAccess; - - private: - using Base = variant_internal::VariantBase<T0, Tn...>; - - public: - // Constructors - - // Constructs a variant holding a default-initialized value of the first - // alternative type. - constexpr variant() /*noexcept(see 111above)*/ = default; - - // Copy constructor, standard semantics - variant(const variant& other) = default; - - // Move constructor, standard semantics - variant(variant&& other) /*noexcept(see above)*/ = default; - - // Constructs a variant of an alternative type specified by overload - // resolution of the provided forwarding arguments through - // direct-initialization. - // - // Note: If the selected constructor is a constexpr constructor, this - // constructor shall be a constexpr constructor. - // - // NOTE: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0608r1.html - // has been voted passed the design phase in the C++ standard meeting in Mar - // 2018. It will be implemented and integrated into `absl::variant`. - template < - class T, - std::size_t I = std::enable_if< - variant_internal::IsNeitherSelfNorInPlace<variant, - absl::decay_t<T>>::value, - variant_internal::IndexOfConstructedType<variant, T>>::type::value, - class Tj = absl::variant_alternative_t<I, variant>, - absl::enable_if_t<std::is_constructible<Tj, T>::value>* = - nullptr> - constexpr variant(T&& t) noexcept(std::is_nothrow_constructible<Tj, T>::value) - : Base(variant_internal::EmplaceTag<I>(), absl::forward<T>(t)) {} - - // Constructs a variant of an alternative type from the arguments through - // direct-initialization. - // - // Note: If the selected constructor is a constexpr constructor, this - // constructor shall be a constexpr constructor. - template <class T, class... Args, - typename std::enable_if<std::is_constructible< - variant_internal::UnambiguousTypeOfT<variant, T>, - Args...>::value>::type* = nullptr> - constexpr explicit variant(in_place_type_t<T>, Args&&... args) - : Base(variant_internal::EmplaceTag< - variant_internal::UnambiguousIndexOf<variant, T>::value>(), - absl::forward<Args>(args)...) {} - - // Constructs a variant of an alternative type from an initializer list - // and other arguments through direct-initialization. - // - // Note: If the selected constructor is a constexpr constructor, this - // constructor shall be a constexpr constructor. - template <class T, class U, class... Args, - typename std::enable_if<std::is_constructible< - variant_internal::UnambiguousTypeOfT<variant, T>, - std::initializer_list<U>&, Args...>::value>::type* = nullptr> - constexpr explicit variant(in_place_type_t<T>, std::initializer_list<U> il, - Args&&... args) - : Base(variant_internal::EmplaceTag< - variant_internal::UnambiguousIndexOf<variant, T>::value>(), - il, absl::forward<Args>(args)...) {} - - // Constructs a variant of an alternative type from a provided index, - // through value-initialization using the provided forwarded arguments. - template <std::size_t I, class... Args, - typename std::enable_if<std::is_constructible< - variant_internal::VariantAlternativeSfinaeT<I, variant>, - Args...>::value>::type* = nullptr> - constexpr explicit variant(in_place_index_t<I>, Args&&... args) - : Base(variant_internal::EmplaceTag<I>(), absl::forward<Args>(args)...) {} - - // Constructs a variant of an alternative type from a provided index, - // through value-initialization of an initializer list and the provided - // forwarded arguments. - template <std::size_t I, class U, class... Args, - typename std::enable_if<std::is_constructible< - variant_internal::VariantAlternativeSfinaeT<I, variant>, - std::initializer_list<U>&, Args...>::value>::type* = nullptr> - constexpr explicit variant(in_place_index_t<I>, std::initializer_list<U> il, - Args&&... args) - : Base(variant_internal::EmplaceTag<I>(), il, - absl::forward<Args>(args)...) {} - - // Destructors - - // Destroys the variant's currently contained value, provided that - // `absl::valueless_by_exception()` is false. - ~variant() = default; - - // Assignment Operators - - // Copy assignment operator - variant& operator=(const variant& other) = default; - - // Move assignment operator - variant& operator=(variant&& other) /*noexcept(see above)*/ = default; - - // Converting assignment operator - // - // NOTE: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0608r1.html - // has been voted passed the design phase in the C++ standard meeting in Mar - // 2018. It will be implemented and integrated into `absl::variant`. - template < - class T, - std::size_t I = std::enable_if< - !std::is_same<absl::decay_t<T>, variant>::value, - variant_internal::IndexOfConstructedType<variant, T>>::type::value, - class Tj = absl::variant_alternative_t<I, variant>, - typename std::enable_if<std::is_assignable<Tj&, T>::value && - std::is_constructible<Tj, T>::value>::type* = - nullptr> - variant& operator=(T&& t) noexcept( - std::is_nothrow_assignable<Tj&, T>::value&& - std::is_nothrow_constructible<Tj, T>::value) { - variant_internal::VisitIndices<sizeof...(Tn) + 1>::Run( - variant_internal::VariantCoreAccess::MakeConversionAssignVisitor( - this, absl::forward<T>(t)), - index()); - - return *this; - } - - - // emplace() Functions - - // Constructs a value of the given alternative type T within the variant. - // - // Example: - // - // absl::variant<std::vector<int>, int, std::string> v; - // v.emplace<int>(99); - // v.emplace<std::string>("abc"); - template < - class T, class... Args, - typename std::enable_if<std::is_constructible< - absl::variant_alternative_t< - variant_internal::UnambiguousIndexOf<variant, T>::value, variant>, - Args...>::value>::type* = nullptr> - T& emplace(Args&&... args) { - return variant_internal::VariantCoreAccess::Replace< - variant_internal::UnambiguousIndexOf<variant, T>::value>( - this, absl::forward<Args>(args)...); - } - - // Constructs a value of the given alternative type T within the variant using - // an initializer list. - // - // Example: - // - // absl::variant<std::vector<int>, int, std::string> v; - // v.emplace<std::vector<int>>({0, 1, 2}); - template < - class T, class U, class... Args, - typename std::enable_if<std::is_constructible< - absl::variant_alternative_t< - variant_internal::UnambiguousIndexOf<variant, T>::value, variant>, - std::initializer_list<U>&, Args...>::value>::type* = nullptr> - T& emplace(std::initializer_list<U> il, Args&&... args) { - return variant_internal::VariantCoreAccess::Replace< - variant_internal::UnambiguousIndexOf<variant, T>::value>( - this, il, absl::forward<Args>(args)...); - } - - // Destroys the current value of the variant (provided that - // `absl::valueless_by_exception()` is false, and constructs a new value at - // the given index. - // - // Example: - // - // absl::variant<std::vector<int>, int, int> v; - // v.emplace<1>(99); - // v.emplace<2>(98); - // v.emplace<int>(99); // Won't compile. 'int' isn't a unique type. - template <std::size_t I, class... Args, - typename std::enable_if< - std::is_constructible<absl::variant_alternative_t<I, variant>, - Args...>::value>::type* = nullptr> - absl::variant_alternative_t<I, variant>& emplace(Args&&... args) { - return variant_internal::VariantCoreAccess::Replace<I>( - this, absl::forward<Args>(args)...); - } - - // Destroys the current value of the variant (provided that - // `absl::valueless_by_exception()` is false, and constructs a new value at - // the given index using an initializer list and the provided arguments. - // - // Example: - // - // absl::variant<std::vector<int>, int, int> v; - // v.emplace<0>({0, 1, 2}); - template <std::size_t I, class U, class... Args, - typename std::enable_if<std::is_constructible< - absl::variant_alternative_t<I, variant>, - std::initializer_list<U>&, Args...>::value>::type* = nullptr> - absl::variant_alternative_t<I, variant>& emplace(std::initializer_list<U> il, - Args&&... args) { - return variant_internal::VariantCoreAccess::Replace<I>( - this, il, absl::forward<Args>(args)...); - } - - // variant::valueless_by_exception() - // - // Returns false if and only if the variant currently holds a valid value. - constexpr bool valueless_by_exception() const noexcept { - return this->index_ == absl::variant_npos; - } - - // variant::index() - // - // Returns the index value of the variant's currently selected alternative - // type. - constexpr std::size_t index() const noexcept { return this->index_; } - - // variant::swap() - // - // Swaps the values of two variant objects. - // - void swap(variant& rhs) noexcept( - absl::conjunction< - std::is_nothrow_move_constructible<T0>, - std::is_nothrow_move_constructible<Tn>..., - type_traits_internal::IsNothrowSwappable<T0>, - type_traits_internal::IsNothrowSwappable<Tn>...>::value) { - return variant_internal::VisitIndices<sizeof...(Tn) + 1>::Run( - variant_internal::Swap<T0, Tn...>{this, &rhs}, rhs.index()); - } -}; - -// We need a valid declaration of variant<> for SFINAE and overload resolution -// to work properly above, but we don't need a full declaration since this type -// will never be constructed. This declaration, though incomplete, suffices. -template <> -class variant<>; - -//------------------------------------------------------------------------------ -// Relational Operators -//------------------------------------------------------------------------------ -// -// If neither operand is in the `variant::valueless_by_exception` state: -// -// * If the index of both variants is the same, the relational operator -// returns the result of the corresponding relational operator for the -// corresponding alternative type. -// * If the index of both variants is not the same, the relational operator -// returns the result of that operation applied to the value of the left -// operand's index and the value of the right operand's index. -// * If at least one operand is in the valueless_by_exception state: -// - A variant in the valueless_by_exception state is only considered equal -// to another variant in the valueless_by_exception state. -// - If exactly one operand is in the valueless_by_exception state, the -// variant in the valueless_by_exception state is less than the variant -// that is not in the valueless_by_exception state. -// -// Note: The value 1 is added to each index in the relational comparisons such -// that the index corresponding to the valueless_by_exception state wraps around -// to 0 (the lowest value for the index type), and the remaining indices stay in -// the same relative order. - -// Equal-to operator -template <typename... Types> -constexpr variant_internal::RequireAllHaveEqualT<Types...> operator==( - const variant<Types...>& a, const variant<Types...>& b) { - return (a.index() == b.index()) && - variant_internal::VisitIndices<sizeof...(Types)>::Run( - variant_internal::EqualsOp<Types...>{&a, &b}, a.index()); -} - -// Not equal operator -template <typename... Types> -constexpr variant_internal::RequireAllHaveNotEqualT<Types...> operator!=( - const variant<Types...>& a, const variant<Types...>& b) { - return (a.index() != b.index()) || - variant_internal::VisitIndices<sizeof...(Types)>::Run( - variant_internal::NotEqualsOp<Types...>{&a, &b}, a.index()); -} - -// Less-than operator -template <typename... Types> -constexpr variant_internal::RequireAllHaveLessThanT<Types...> operator<( - const variant<Types...>& a, const variant<Types...>& b) { - return (a.index() != b.index()) - ? (a.index() + 1) < (b.index() + 1) - : variant_internal::VisitIndices<sizeof...(Types)>::Run( - variant_internal::LessThanOp<Types...>{&a, &b}, a.index()); -} - -// Greater-than operator -template <typename... Types> -constexpr variant_internal::RequireAllHaveGreaterThanT<Types...> operator>( - const variant<Types...>& a, const variant<Types...>& b) { - return (a.index() != b.index()) - ? (a.index() + 1) > (b.index() + 1) - : variant_internal::VisitIndices<sizeof...(Types)>::Run( - variant_internal::GreaterThanOp<Types...>{&a, &b}, - a.index()); -} - -// Less-than or equal-to operator -template <typename... Types> -constexpr variant_internal::RequireAllHaveLessThanOrEqualT<Types...> operator<=( - const variant<Types...>& a, const variant<Types...>& b) { - return (a.index() != b.index()) - ? (a.index() + 1) < (b.index() + 1) - : variant_internal::VisitIndices<sizeof...(Types)>::Run( - variant_internal::LessThanOrEqualsOp<Types...>{&a, &b}, - a.index()); -} - -// Greater-than or equal-to operator -template <typename... Types> -constexpr variant_internal::RequireAllHaveGreaterThanOrEqualT<Types...> -operator>=(const variant<Types...>& a, const variant<Types...>& b) { - return (a.index() != b.index()) - ? (a.index() + 1) > (b.index() + 1) - : variant_internal::VisitIndices<sizeof...(Types)>::Run( - variant_internal::GreaterThanOrEqualsOp<Types...>{&a, &b}, - a.index()); -} - -ABSL_NAMESPACE_END -} // namespace absl - -namespace std { - -// hash() -template <> // NOLINT -struct hash<absl::monostate> { - std::size_t operator()(absl::monostate) const { return 0; } -}; - -template <class... T> // NOLINT -struct hash<absl::variant<T...>> - : absl::variant_internal::VariantHashBase<absl::variant<T...>, void, - absl::remove_const_t<T>...> {}; - -} // namespace std - -#endif // ABSL_USES_STD_VARIANT - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace variant_internal { - -// Helper visitor for converting a variant<Ts...>` into another type (mostly -// variant) that can be constructed from any type. -template <typename To> -struct ConversionVisitor { - template <typename T> - To operator()(T&& v) const { - return To(std::forward<T>(v)); - } -}; - -} // namespace variant_internal - -// ConvertVariantTo() -// -// Helper functions to convert an `absl::variant` to a variant of another set of -// types, provided that the alternative type of the new variant type can be -// converted from any type in the source variant. -// -// Example: -// -// absl::variant<name1, name2, float> InternalReq(const Req&); -// -// // name1 and name2 are convertible to name -// absl::variant<name, float> ExternalReq(const Req& req) { -// return absl::ConvertVariantTo<absl::variant<name, float>>( -// InternalReq(req)); -// } -template <typename To, typename Variant> -To ConvertVariantTo(Variant&& variant) { - return absl::visit(variant_internal::ConversionVisitor<To>{}, - std::forward<Variant>(variant)); -} - -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_TYPES_VARIANT_H_ |