// SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
// This is based on the proposed implementation of std::expected (P0323)
// https://github.com/TartanLlama/expected/blob/master/include/tl/expected.hpp
#pragma once
#include <type_traits>
#include <utility>
namespace Common {
template <typename T, typename E>
class Expected;
template <typename E>
class Unexpected {
public:
Unexpected() = delete;
constexpr explicit Unexpected(const E& e) : m_val{e} {}
constexpr explicit Unexpected(E&& e) : m_val{std::move(e)} {}
constexpr E& value() & {
return m_val;
}
constexpr const E& value() const& {
return m_val;
}
constexpr E&& value() && {
return std::move(m_val);
}
constexpr const E&& value() const&& {
return std::move(m_val);
}
private:
E m_val;
};
template <typename E>
constexpr auto operator<=>(const Unexpected<E>& lhs, const Unexpected<E>& rhs) {
return lhs.value() <=> rhs.value();
}
struct unexpect_t {
constexpr explicit unexpect_t() = default;
};
namespace detail {
struct no_init_t {
constexpr explicit no_init_t() = default;
};
/**
* This specialization is for when T is not trivially destructible,
* so the destructor must be called on destruction of `expected'
* Additionally, this requires E to be trivially destructible
*/
template <typename T, typename E, bool = std::is_trivially_destructible_v<T>>
requires std::is_trivially_destructible_v<E>
struct expected_storage_base {
constexpr expected_storage_base() : m_val{T{}}, m_has_val{true} {}
constexpr expected_storage_base(no_init_t) : m_has_val{false} {}
template <typename... Args, std::enable_if_t<std::is_constructible_v<T, Args&&...>>* = nullptr>
constexpr expected_storage_base(std::in_place_t, Args&&... args)
: m_val{std::forward<Args>(args)...}, m_has_val{true} {}
template <typename U, typename... Args,
std::enable_if_t<std::is_constructible_v<T, std::initializer_list<U>&, Args&&...>>* =
nullptr>
constexpr expected_storage_base(std::in_place_t, std::initializer_list<U> il, Args&&... args)
: m_val{il, std::forward<Args>(args)...}, m_has_val{true} {}
template <typename... Args, std::enable_if_t<std::is_constructible_v<E, Args&&...>>* = nullptr>
constexpr explicit expected_storage_base(unexpect_t, Args&&... args)
: m_unexpect{std::forward<Args>(args)...}, m_has_val{false} {}
template <typename U, typename... Args,
std::enable_if_t<std::is_constructible_v<E, std::initializer_list<U>&, Args&&...>>* =
nullptr>
constexpr explicit expected_storage_base(unexpect_t, std::initializer_list<U> il,
Args&&... args)
: m_unexpect{il, std::forward<Args>(args)...}, m_has_val{false} {}
~expected_storage_base() {
if (m_has_val) {
m_val.~T();
}
}
union {
T m_val;
Unexpected<E> m_unexpect;
};
bool m_has_val;
};
/**
* This specialization is for when T is trivially destructible,
* so the destructor of `expected` can be trivial
* Additionally, this requires E to be trivially destructible
*/
template <typename T, typename E>
requires std::is_trivially_destructible_v<E>
struct expected_storage_base<T, E, true> {
constexpr expected_storage_base() : m_val{T{}}, m_has_val{true} {}
constexpr expected_storage_base(no_init_t) : m_has_val{false} {}
template <typename... Args, std::enable_if_t<std::is_constructible_v<T, Args&&...>>* = nullptr>
constexpr expected_storage_base(std::in_place_t, Args&&... args)
: m_val{std::forward<Args>(args)...}, m_has_val{true} {}
template <typename U, typename... Args,
std::enable_if_t<std::is_constructible_v<T, std::initializer_list<U>&, Args&&...>>* =
nullptr>
constexpr expected_storage_base(std::in_place_t, std::initializer_list<U> il, Args&&... args)
: m_val{il, std::forward<Args>(args)...}, m_has_val{true} {}
template <typename... Args, std::enable_if_t<std::is_constructible_v<E, Args&&...>>* = nullptr>
constexpr explicit expected_storage_base(unexpect_t, Args&&... args)
: m_unexpect{std::forward<Args>(args)...}, m_has_val{false} {}
template <typename U, typename... Args,
std::enable_if_t<std::is_constructible_v<E, std::initializer_list<U>&, Args&&...>>* =
nullptr>
constexpr explicit expected_storage_base(unexpect_t, std::initializer_list<U> il,
Args&&... args)
: m_unexpect{il, std::forward<Args>(args)...}, m_has_val{false} {}
~expected_storage_base() = default;
union {
T m_val;
Unexpected<E> m_unexpect;
};
bool m_has_val;
};
template <typename T, typename E>
struct expected_operations_base : expected_storage_base<T, E> {
using expected_storage_base<T, E>::expected_storage_base;
template <typename... Args>
void construct(Args&&... args) noexcept {
new (std::addressof(this->m_val)) T{std::forward<Args>(args)...};
this->m_has_val = true;
}
template <typename Rhs>
void construct_with(Rhs&& rhs) noexcept {
new (std::addressof(this->m_val)) T{std::forward<Rhs>(rhs).get()};
this->m_has_val = true;
}
template <typename... Args>
void construct_error(Args&&... args) noexcept {
new (std::addressof(this->m_unexpect)) Unexpected<E>{std::forward<Args>(args)...};
this->m_has_val = false;
}
void assign(const expected_operations_base& rhs) noexcept {
if (!this->m_has_val && rhs.m_has_val) {
geterr().~Unexpected<E>();
construct(rhs.get());
} else {
assign_common(rhs);
}
}
void assign(expected_operations_base&& rhs) noexcept {
if (!this->m_has_val && rhs.m_has_val) {
geterr().~Unexpected<E>();
construct(std::move(rhs).get());
} else {
assign_common(rhs);
}
}
template <typename Rhs>
void assign_common(Rhs&& rhs) {
if (this->m_has_val) {
if (rhs.m_has_val) {
get() = std::forward<Rhs>(rhs).get();
} else {
destroy_val();
construct_error(std::forward<Rhs>(rhs).geterr());
}
} else {
if (!rhs.m_has_val) {
geterr() = std::forward<Rhs>(rhs).geterr();
}
}
}
bool has_value() const {
return this->m_has_val;
}
constexpr T& get() & {
return this->m_val;
}
constexpr const T& get() const& {
return this->m_val;
}
constexpr T&& get() && {
return std::move(this->m_val);
}
constexpr const T&& get() const&& {
return std::move(this->m_val);
}
constexpr Unexpected<E>& geterr() & {
return this->m_unexpect;
}
constexpr const Unexpected<E>& geterr() const& {
return this->m_unexpect;
}
constexpr Unexpected<E>&& geterr() && {
return std::move(this->m_unexpect);
}
constexpr const Unexpected<E>&& geterr() const&& {
return std::move(this->m_unexpect);
}
constexpr void destroy_val() {
get().~T();
}
};
/**
* This manages conditionally having a trivial copy constructor
* This specialization is for when T is trivially copy constructible
* Additionally, this requires E to be trivially copy constructible
*/
template <typename T, typename E, bool = std::is_trivially_copy_constructible_v<T>>
requires std::is_trivially_copy_constructible_v<E>
struct expected_copy_base : expected_operations_base<T, E> {
using expected_operations_base<T, E>::expected_operations_base;
};
/**
* This specialization is for when T is not trivially copy constructible
* Additionally, this requires E to be trivially copy constructible
*/
template <typename T, typename E>
requires std::is_trivially_copy_constructible_v<E>
struct expected_copy_base<T, E, false> : expected_operations_base<T, E> {
using expected_operations_base<T, E>::expected_operations_base;
expected_copy_base() = default;
expected_copy_base(const expected_copy_base& rhs)
: expected_operations_base<T, E>{no_init_t{}} {
if (rhs.has_value()) {
this->construct_with(rhs);
} else {
this->construct_error(rhs.geterr());
}
}
expected_copy_base(expected_copy_base&&) = default;
expected_copy_base& operator=(const expected_copy_base&) = default;
expected_copy_base& operator=(expected_copy_base&&) = default;
};
/**
* This manages conditionally having a trivial move constructor
* This specialization is for when T is trivially move constructible
* Additionally, this requires E to be trivially move constructible
*/
template <typename T, typename E, bool = std::is_trivially_move_constructible_v<T>>
requires std::is_trivially_move_constructible_v<E>
struct expected_move_base : expected_copy_base<T, E> {
using expected_copy_base<T, E>::expected_copy_base;
};
/**
* This specialization is for when T is not trivially move constructible
* Additionally, this requires E to be trivially move constructible
*/
template <typename T, typename E>
requires std::is_trivially_move_constructible_v<E>
struct expected_move_base<T, E, false> : expected_copy_base<T, E> {
using expected_copy_base<T, E>::expected_copy_base;
expected_move_base() = default;
expected_move_base(const expected_move_base&) = default;
expected_move_base(expected_move_base&& rhs) noexcept(std::is_nothrow_move_constructible_v<T>)
: expected_copy_base<T, E>{no_init_t{}} {
if (rhs.has_value()) {
this->construct_with(std::move(rhs));
} else {
this->construct_error(std::move(rhs.geterr()));
}
}
expected_move_base& operator=(const expected_move_base&) = default;
expected_move_base& operator=(expected_move_base&&) = default;
};
/**
* This manages conditionally having a trivial copy assignment operator
* This specialization is for when T is trivially copy assignable
* Additionally, this requires E to be trivially copy assignable
*/
template <typename T, typename E,
bool = std::conjunction_v<std::is_trivially_copy_assignable<T>,
std::is_trivially_copy_constructible<T>,
std::is_trivially_destructible<T>>>
requires std::conjunction_v<std::is_trivially_copy_assignable<E>,
std::is_trivially_copy_constructible<E>,
std::is_trivially_destructible<E>>
struct expected_copy_assign_base : expected_move_base<T, E> {
using expected_move_base<T, E>::expected_move_base;
};
/**
* This specialization is for when T is not trivially copy assignable
* Additionally, this requires E to be trivially copy assignable
*/
template <typename T, typename E>
requires std::conjunction_v<std::is_trivially_copy_assignable<E>,
std::is_trivially_copy_constructible<E>,
std::is_trivially_destructible<E>>
struct expected_copy_assign_base<T, E, false> : expected_move_base<T, E> {
using expected_move_base<T, E>::expected_move_base;
expected_copy_assign_base() = default;
expected_copy_assign_base(const expected_copy_assign_base&) = default;
expected_copy_assign_base(expected_copy_assign_base&&) = default;
expected_copy_assign_base& operator=(const expected_copy_assign_base& rhs) {
this->assign(rhs);
return *this;
}
expected_copy_assign_base& operator=(expected_copy_assign_base&&) = default;
};
/**
* This manages conditionally having a trivial move assignment operator
* This specialization is for when T is trivially move assignable
* Additionally, this requires E to be trivially move assignable
*/
template <typename T, typename E,
bool = std::conjunction_v<std::is_trivially_move_assignable<T>,
std::is_trivially_move_constructible<T>,
std::is_trivially_destructible<T>>>
requires std::conjunction_v<std::is_trivially_move_assignable<E>,
std::is_trivially_move_constructible<E>,
std::is_trivially_destructible<E>>
struct expected_move_assign_base : expected_copy_assign_base<T, E> {
using expected_copy_assign_base<T, E>::expected_copy_assign_base;
};
/**
* This specialization is for when T is not trivially move assignable
* Additionally, this requires E to be trivially move assignable
*/
template <typename T, typename E>
requires std::conjunction_v<std::is_trivially_move_assignable<E>,
std::is_trivially_move_constructible<E>,
std::is_trivially_destructible<E>>
struct expected_move_assign_base<T, E, false> : expected_copy_assign_base<T, E> {
using expected_copy_assign_base<T, E>::expected_copy_assign_base;
expected_move_assign_base() = default;
expected_move_assign_base(const expected_move_assign_base&) = default;
expected_move_assign_base(expected_move_assign_base&&) = default;
expected_move_assign_base& operator=(const expected_move_assign_base&) = default;
expected_move_assign_base& operator=(expected_move_assign_base&& rhs) noexcept(
std::conjunction_v<std::is_nothrow_move_constructible<T>,
std::is_nothrow_move_assignable<T>>) {
this->assign(std::move(rhs));
return *this;
}
};
/**
* expected_delete_ctor_base will conditionally delete copy and move constructors
* depending on whether T is copy/move constructible
* Additionally, this requires E to be copy/move constructible
*/
template <typename T, typename E, bool EnableCopy = std::is_copy_constructible_v<T>,
bool EnableMove = std::is_move_constructible_v<T>>
requires std::conjunction_v<std::is_copy_constructible<E>, std::is_move_constructible<E>>
struct expected_delete_ctor_base {
expected_delete_ctor_base() = default;
expected_delete_ctor_base(const expected_delete_ctor_base&) = default;
expected_delete_ctor_base(expected_delete_ctor_base&&) noexcept = default;
expected_delete_ctor_base& operator=(const expected_delete_ctor_base&) = default;
expected_delete_ctor_base& operator=(expected_delete_ctor_base&&) noexcept = default;
};
template <typename T, typename E>
requires std::conjunction_v<std::is_copy_constructible<E>, std::is_move_constructible<E>>
struct expected_delete_ctor_base<T, E, true, false> {
expected_delete_ctor_base() = default;
expected_delete_ctor_base(const expected_delete_ctor_base&) = default;
expected_delete_ctor_base(expected_delete_ctor_base&&) noexcept = delete;
expected_delete_ctor_base& operator=(const expected_delete_ctor_base&) = default;
expected_delete_ctor_base& operator=(expected_delete_ctor_base&&) noexcept = default;
};
template <typename T, typename E>
requires std::conjunction_v<std::is_copy_constructible<E>, std::is_move_constructible<E>>
struct expected_delete_ctor_base<T, E, false, true> {
expected_delete_ctor_base() = default;
expected_delete_ctor_base(const expected_delete_ctor_base&) = delete;
expected_delete_ctor_base(expected_delete_ctor_base&&) noexcept = default;
expected_delete_ctor_base& operator=(const expected_delete_ctor_base&) = default;
expected_delete_ctor_base& operator=(expected_delete_ctor_base&&) noexcept = default;
};
template <typename T, typename E>
requires std::conjunction_v<std::is_copy_constructible<E>, std::is_move_constructible<E>>
struct expected_delete_ctor_base<T, E, false, false> {
expected_delete_ctor_base() = default;
expected_delete_ctor_base(const expected_delete_ctor_base&) = delete;
expected_delete_ctor_base(expected_delete_ctor_base&&) noexcept = delete;
expected_delete_ctor_base& operator=(const expected_delete_ctor_base&) = default;
expected_delete_ctor_base& operator=(expected_delete_ctor_base&&) noexcept = default;
};
/**
* expected_delete_assign_base will conditionally delete copy and move assignment operators
* depending on whether T is copy/move constructible + assignable
* Additionally, this requires E to be copy/move constructible + assignable
*/
template <
typename T, typename E,
bool EnableCopy = std::conjunction_v<std::is_copy_constructible<T>, std::is_copy_assignable<T>>,
bool EnableMove = std::conjunction_v<std::is_move_constructible<T>, std::is_move_assignable<T>>>
requires std::conjunction_v<std::is_copy_constructible<E>, std::is_move_constructible<E>,
std::is_copy_assignable<E>, std::is_move_assignable<E>>
struct expected_delete_assign_base {
expected_delete_assign_base() = default;
expected_delete_assign_base(const expected_delete_assign_base&) = default;
expected_delete_assign_base(expected_delete_assign_base&&) noexcept = default;
expected_delete_assign_base& operator=(const expected_delete_assign_base&) = default;
expected_delete_assign_base& operator=(expected_delete_assign_base&&) noexcept = default;
};
template <typename T, typename E>
requires std::conjunction_v<std::is_copy_constructible<E>, std::is_move_constructible<E>,
std::is_copy_assignable<E>, std::is_move_assignable<E>>
struct expected_delete_assign_base<T, E, true, false> {
expected_delete_assign_base() = default;
expected_delete_assign_base(const expected_delete_assign_base&) = default;
expected_delete_assign_base(expected_delete_assign_base&&) noexcept = default;
expected_delete_assign_base& operator=(const expected_delete_assign_base&) = default;
expected_delete_assign_base& operator=(expected_delete_assign_base&&) noexcept = delete;
};
template <typename T, typename E>
requires std::conjunction_v<std::is_copy_constructible<E>, std::is_move_constructible<E>,
std::is_copy_assignable<E>, std::is_move_assignable<E>>
struct expected_delete_assign_base<T, E, false, true> {
expected_delete_assign_base() = default;
expected_delete_assign_base(const expected_delete_assign_base&) = default;
expected_delete_assign_base(expected_delete_assign_base&&) noexcept = default;
expected_delete_assign_base& operator=(const expected_delete_assign_base&) = delete;
expected_delete_assign_base& operator=(expected_delete_assign_base&&) noexcept = default;
};
template <typename T, typename E>
requires std::conjunction_v<std::is_copy_constructible<E>, std::is_move_constructible<E>,
std::is_copy_assignable<E>, std::is_move_assignable<E>>
struct expected_delete_assign_base<T, E, false, false> {
expected_delete_assign_base() = default;
expected_delete_assign_base(const expected_delete_assign_base&) = default;
expected_delete_assign_base(expected_delete_assign_base&&) noexcept = default;
expected_delete_assign_base& operator=(const expected_delete_assign_base&) = delete;
expected_delete_assign_base& operator=(expected_delete_assign_base&&) noexcept = delete;
};
/**
* This is needed to be able to construct the expected_default_ctor_base which follows,
* while still conditionally deleting the default constructor.
*/
struct default_constructor_tag {
constexpr explicit default_constructor_tag() = default;
};
/**
* expected_default_ctor_base will ensure that expected
* has a deleted default constructor if T is not default constructible
* This specialization is for when T is default constructible
*/
template <typename T, typename E, bool Enable = std::is_default_constructible_v<T>>
struct expected_default_ctor_base {
constexpr expected_default_ctor_base() noexcept = default;
constexpr expected_default_ctor_base(expected_default_ctor_base const&) noexcept = default;
constexpr expected_default_ctor_base(expected_default_ctor_base&&) noexcept = default;
expected_default_ctor_base& operator=(expected_default_ctor_base const&) noexcept = default;
expected_default_ctor_base& operator=(expected_default_ctor_base&&) noexcept = default;
constexpr explicit expected_default_ctor_base(default_constructor_tag) {}
};
template <typename T, typename E>
struct expected_default_ctor_base<T, E, false> {
constexpr expected_default_ctor_base() noexcept = delete;
constexpr expected_default_ctor_base(expected_default_ctor_base const&) noexcept = default;
constexpr expected_default_ctor_base(expected_default_ctor_base&&) noexcept = default;
expected_default_ctor_base& operator=(expected_default_ctor_base const&) noexcept = default;
expected_default_ctor_base& operator=(expected_default_ctor_base&&) noexcept = default;
constexpr explicit expected_default_ctor_base(default_constructor_tag) {}
};
template <typename T, typename E, typename U>
using expected_enable_forward_value =
std::enable_if_t<std::is_constructible_v<T, U&&> &&
!std::is_same_v<std::remove_cvref_t<U>, std::in_place_t> &&
!std::is_same_v<Expected<T, E>, std::remove_cvref_t<U>> &&
!std::is_same_v<Unexpected<E>, std::remove_cvref_t<U>>>;
template <typename T, typename E, typename U, typename G, typename UR, typename GR>
using expected_enable_from_other = std::enable_if_t<
std::is_constructible_v<T, UR> && std::is_constructible_v<E, GR> &&
!std::is_constructible_v<T, Expected<U, G>&> && !std::is_constructible_v<T, Expected<U, G>&&> &&
!std::is_constructible_v<T, const Expected<U, G>&> &&
!std::is_constructible_v<T, const Expected<U, G>&&> &&
!std::is_convertible_v<Expected<U, G>&, T> && !std::is_convertible_v<Expected<U, G>&&, T> &&
!std::is_convertible_v<const Expected<U, G>&, T> &&
!std::is_convertible_v<const Expected<U, G>&&, T>>;
} // namespace detail
template <typename T, typename E>
class Expected : private detail::expected_move_assign_base<T, E>,
private detail::expected_delete_ctor_base<T, E>,
private detail::expected_delete_assign_base<T, E>,
private detail::expected_default_ctor_base<T, E> {
public:
using value_type = T;
using error_type = E;
using unexpected_type = Unexpected<E>;
constexpr Expected() = default;
constexpr Expected(const Expected&) = default;
constexpr Expected(Expected&&) = default;
Expected& operator=(const Expected&) = default;
Expected& operator=(Expected&&) = default;
template <typename... Args, std::enable_if_t<std::is_constructible_v<T, Args&&...>>* = nullptr>
constexpr Expected(std::in_place_t, Args&&... args)
: impl_base{std::in_place, std::forward<Args>(args)...},
ctor_base{detail::default_constructor_tag{}} {}
template <typename U, typename... Args,
std::enable_if_t<std::is_constructible_v<T, std::initializer_list<U>&, Args&&...>>* =
nullptr>
constexpr Expected(std::in_place_t, std::initializer_list<U> il, Args&&... args)
: impl_base{std::in_place, il, std::forward<Args>(args)...},
ctor_base{detail::default_constructor_tag{}} {}
template <typename G = E, std::enable_if_t<std::is_constructible_v<E, const G&>>* = nullptr,
std::enable_if_t<!std::is_convertible_v<const G&, E>>* = nullptr>
constexpr explicit Expected(const Unexpected<G>& e)
: impl_base{unexpect_t{}, e.value()}, ctor_base{detail::default_constructor_tag{}} {}
template <typename G = E, std::enable_if_t<std::is_constructible_v<E, const G&>>* = nullptr,
std::enable_if_t<std::is_convertible_v<const G&, E>>* = nullptr>
constexpr Expected(Unexpected<G> const& e)
: impl_base{unexpect_t{}, e.value()}, ctor_base{detail::default_constructor_tag{}} {}
template <typename G = E, std::enable_if_t<std::is_constructible_v<E, G&&>>* = nullptr,
std::enable_if_t<!std::is_convertible_v<G&&, E>>* = nullptr>
constexpr explicit Expected(Unexpected<G>&& e) noexcept(std::is_nothrow_constructible_v<E, G&&>)
: impl_base{unexpect_t{}, std::move(e.value())}, ctor_base{
detail::default_constructor_tag{}} {}
template <typename G = E, std::enable_if_t<std::is_constructible_v<E, G&&>>* = nullptr,
std::enable_if_t<std::is_convertible_v<G&&, E>>* = nullptr>
constexpr Expected(Unexpected<G>&& e) noexcept(std::is_nothrow_constructible_v<E, G&&>)
: impl_base{unexpect_t{}, std::move(e.value())}, ctor_base{
detail::default_constructor_tag{}} {}
template <typename... Args, std::enable_if_t<std::is_constructible_v<E, Args&&...>>* = nullptr>
constexpr explicit Expected(unexpect_t, Args&&... args)
: impl_base{unexpect_t{}, std::forward<Args>(args)...},
ctor_base{detail::default_constructor_tag{}} {}
template <typename U, typename... Args,
std::enable_if_t<std::is_constructible_v<E, std::initializer_list<U>&, Args&&...>>* =
nullptr>
constexpr explicit Expected(unexpect_t, std::initializer_list<U> il, Args&&... args)
: impl_base{unexpect_t{}, il, std::forward<Args>(args)...},
ctor_base{detail::default_constructor_tag{}} {}
template <typename U, typename G,
std::enable_if_t<!(std::is_convertible_v<U const&, T> &&
std::is_convertible_v<G const&, E>)>* = nullptr,
detail::expected_enable_from_other<T, E, U, G, const U&, const G&>* = nullptr>
constexpr explicit Expected(const Expected<U, G>& rhs)
: ctor_base{detail::default_constructor_tag{}} {
if (rhs.has_value()) {
this->construct(*rhs);
} else {
this->construct_error(rhs.error());
}
}
template <typename U, typename G,
std::enable_if_t<(std::is_convertible_v<U const&, T> &&
std::is_convertible_v<G const&, E>)>* = nullptr,
detail::expected_enable_from_other<T, E, U, G, const U&, const G&>* = nullptr>
constexpr Expected(const Expected<U, G>& rhs) : ctor_base{detail::default_constructor_tag{}} {
if (rhs.has_value()) {
this->construct(*rhs);
} else {
this->construct_error(rhs.error());
}
}
template <typename U, typename G,
std::enable_if_t<!(std::is_convertible_v<U&&, T> && std::is_convertible_v<G&&, E>)>* =
nullptr,
detail::expected_enable_from_other<T, E, U, G, U&&, G&&>* = nullptr>
constexpr explicit Expected(Expected<U, G>&& rhs)
: ctor_base{detail::default_constructor_tag{}} {
if (rhs.has_value()) {
this->construct(std::move(*rhs));
} else {
this->construct_error(std::move(rhs.error()));
}
}
template <typename U, typename G,
std::enable_if_t<(std::is_convertible_v<U&&, T> && std::is_convertible_v<G&&, E>)>* =
nullptr,
detail::expected_enable_from_other<T, E, U, G, U&&, G&&>* = nullptr>
constexpr Expected(Expected<U, G>&& rhs) : ctor_base{detail::default_constructor_tag{}} {
if (rhs.has_value()) {
this->construct(std::move(*rhs));
} else {
this->construct_error(std::move(rhs.error()));
}
}
template <typename U = T, std::enable_if_t<!std::is_convertible_v<U&&, T>>* = nullptr,
detail::expected_enable_forward_value<T, E, U>* = nullptr>
constexpr explicit Expected(U&& v) : Expected{std::in_place, std::forward<U>(v)} {}
template <typename U = T, std::enable_if_t<std::is_convertible_v<U&&, T>>* = nullptr,
detail::expected_enable_forward_value<T, E, U>* = nullptr>
constexpr Expected(U&& v) : Expected{std::in_place, std::forward<U>(v)} {}
template <typename U = T, typename G = T,
std::enable_if_t<std::is_nothrow_constructible_v<T, U&&>>* = nullptr,
std::enable_if_t<(
!std::is_same_v<Expected<T, E>, std::remove_cvref_t<U>> &&
!std::conjunction_v<std::is_scalar<T>, std::is_same<T, std::remove_cvref_t<U>>> &&
std::is_constructible_v<T, U> && std::is_assignable_v<G&, U> &&
std::is_nothrow_move_constructible_v<E>)>* = nullptr>
Expected& operator=(U&& v) {
if (has_value()) {
val() = std::forward<U>(v);
} else {
err().~Unexpected<E>();
new (valptr()) T{std::forward<U>(v)};
this->m_has_val = true;
}
return *this;
}
template <typename U = T, typename G = T,
std::enable_if_t<!std::is_nothrow_constructible_v<T, U&&>>* = nullptr,
std::enable_if_t<(
!std::is_same_v<Expected<T, E>, std::remove_cvref_t<U>> &&
!std::conjunction_v<std::is_scalar<T>, std::is_same<T, std::remove_cvref_t<U>>> &&
std::is_constructible_v<T, U> && std::is_assignable_v<G&, U> &&
std::is_nothrow_move_constructible_v<E>)>* = nullptr>
Expected& operator=(U&& v) {
if (has_value()) {
val() = std::forward<U>(v);
} else {
auto tmp = std::move(err());
err().~Unexpected<E>();
new (valptr()) T{std::forward<U>(v)};
this->m_has_val = true;
}
return *this;
}
template <typename G = E, std::enable_if_t<std::is_nothrow_copy_constructible_v<G> &&
std::is_assignable_v<G&, G>>* = nullptr>
Expected& operator=(const Unexpected<G>& rhs) {
if (!has_value()) {
err() = rhs;
} else {
this->destroy_val();
new (errptr()) Unexpected<E>{rhs};
this->m_has_val = false;
}
return *this;
}
template <typename G = E, std::enable_if_t<std::is_nothrow_move_constructible_v<G> &&
std::is_move_assignable_v<G>>* = nullptr>
Expected& operator=(Unexpected<G>&& rhs) noexcept {
if (!has_value()) {
err() = std::move(rhs);
} else {
this->destroy_val();
new (errptr()) Unexpected<E>{std::move(rhs)};
this->m_has_val = false;
}
return *this;
}
template <typename... Args,
std::enable_if_t<std::is_nothrow_constructible_v<T, Args&&...>>* = nullptr>
void emplace(Args&&... args) {
if (has_value()) {
val() = T{std::forward<Args>(args)...};
} else {
err().~Unexpected<E>();
new (valptr()) T{std::forward<Args>(args)...};
this->m_has_val = true;
}
}
template <typename... Args,
std::enable_if_t<!std::is_nothrow_constructible_v<T, Args&&...>>* = nullptr>
void emplace(Args&&... args) {
if (has_value()) {
val() = T{std::forward<Args>(args)...};
} else {
auto tmp = std::move(err());
err().~Unexpected<E>();
new (valptr()) T{std::forward<Args>(args)...};
this->m_has_val = true;
}
}
template <typename U, typename... Args,
std::enable_if_t<std::is_nothrow_constructible_v<T, std::initializer_list<U>&,
Args&&...>>* = nullptr>
void emplace(std::initializer_list<U> il, Args&&... args) {
if (has_value()) {
T t{il, std::forward<Args>(args)...};
val() = std::move(t);
} else {
err().~Unexpected<E>();
new (valptr()) T{il, std::forward<Args>(args)...};
this->m_has_val = true;
}
}
template <typename U, typename... Args,
std::enable_if_t<!std::is_nothrow_constructible_v<T, std::initializer_list<U>&,
Args&&...>>* = nullptr>
void emplace(std::initializer_list<U> il, Args&&... args) {
if (has_value()) {
T t{il, std::forward<Args>(args)...};
val() = std::move(t);
} else {
auto tmp = std::move(err());
err().~Unexpected<E>();
new (valptr()) T{il, std::forward<Args>(args)...};
this->m_has_val = true;
}
}
constexpr T* operator->() {
return valptr();
}
constexpr const T* operator->() const {
return valptr();
}
template <typename U = T>
constexpr U& operator*() & {
return val();
}
template <typename U = T>
constexpr const U& operator*() const& {
return val();
}
template <typename U = T>
constexpr U&& operator*() && {
return std::move(val());
}
template <typename U = T>
constexpr const U&& operator*() const&& {
return std::move(val());
}
constexpr bool has_value() const noexcept {
return this->m_has_val;
}
constexpr explicit operator bool() const noexcept {
return this->m_has_val;
}
template <typename U = T>
constexpr U& value() & {
return val();
}
template <typename U = T>
constexpr const U& value() const& {
return val();
}
template <typename U = T>
constexpr U&& value() && {
return std::move(val());
}
template <typename U = T>
constexpr const U&& value() const&& {
return std::move(val());
}
constexpr E& error() & {
return err().value();
}
constexpr const E& error() const& {
return err().value();
}
constexpr E&& error() && {
return std::move(err().value());
}
constexpr const E&& error() const&& {
return std::move(err().value());
}
template <typename U>
constexpr T value_or(U&& v) const& {
static_assert(std::is_copy_constructible_v<T> && std::is_convertible_v<U&&, T>,
"T must be copy-constructible and convertible from U&&");
return bool(*this) ? **this : static_cast<T>(std::forward<U>(v));
}
template <typename U>
constexpr T value_or(U&& v) && {
static_assert(std::is_move_constructible_v<T> && std::is_convertible_v<U&&, T>,
"T must be move-constructible and convertible from U&&");
return bool(*this) ? std::move(**this) : static_cast<T>(std::forward<U>(v));
}
private:
static_assert(!std::is_reference_v<T>, "T must not be a reference");
static_assert(!std::is_same_v<T, std::remove_cv_t<std::in_place_t>>,
"T must not be std::in_place_t");
static_assert(!std::is_same_v<T, std::remove_cv_t<unexpect_t>>, "T must not be unexpect_t");
static_assert(!std::is_same_v<T, std::remove_cv_t<Unexpected<E>>>,
"T must not be Unexpected<E>");
static_assert(!std::is_reference_v<E>, "E must not be a reference");
T* valptr() {
return std::addressof(this->m_val);
}
const T* valptr() const {
return std::addressof(this->m_val);
}
Unexpected<E>* errptr() {
return std::addressof(this->m_unexpect);
}
const Unexpected<E>* errptr() const {
return std::addressof(this->m_unexpect);
}
template <typename U = T>
constexpr U& val() {
return this->m_val;
}
template <typename U = T>
constexpr const U& val() const {
return this->m_val;
}
constexpr Unexpected<E>& err() {
return this->m_unexpect;
}
constexpr const Unexpected<E>& err() const {
return this->m_unexpect;
}
using impl_base = detail::expected_move_assign_base<T, E>;
using ctor_base = detail::expected_default_ctor_base<T, E>;
};
template <typename T, typename E, typename U, typename F>
constexpr bool operator==(const Expected<T, E>& lhs, const Expected<U, F>& rhs) {
return (lhs.has_value() != rhs.has_value())
? false
: (!lhs.has_value() ? lhs.error() == rhs.error() : *lhs == *rhs);
}
template <typename T, typename E, typename U, typename F>
constexpr bool operator!=(const Expected<T, E>& lhs, const Expected<U, F>& rhs) {
return !operator==(lhs, rhs);
}
template <typename T, typename E, typename U>
constexpr bool operator==(const Expected<T, E>& x, const U& v) {
return x.has_value() ? *x == v : false;
}
template <typename T, typename E, typename U>
constexpr bool operator==(const U& v, const Expected<T, E>& x) {
return x.has_value() ? *x == v : false;
}
template <typename T, typename E, typename U>
constexpr bool operator!=(const Expected<T, E>& x, const U& v) {
return !operator==(x, v);
}
template <typename T, typename E, typename U>
constexpr bool operator!=(const U& v, const Expected<T, E>& x) {
return !operator==(v, x);
}
template <typename T, typename E>
constexpr bool operator==(const Expected<T, E>& x, const Unexpected<E>& e) {
return x.has_value() ? false : x.error() == e.value();
}
template <typename T, typename E>
constexpr bool operator==(const Unexpected<E>& e, const Expected<T, E>& x) {
return x.has_value() ? false : x.error() == e.value();
}
template <typename T, typename E>
constexpr bool operator!=(const Expected<T, E>& x, const Unexpected<E>& e) {
return !operator==(x, e);
}
template <typename T, typename E>
constexpr bool operator!=(const Unexpected<E>& e, const Expected<T, E>& x) {
return !operator==(e, x);
}
} // namespace Common
