Atmosphere/libraries/libvapours/include/vapours/util/util_optional.hpp

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2021-07-08 09:37:26 +00:00
/*
* Copyright (c) 2018-2020 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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 program. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <vapours/common.hpp>
#include <vapours/assert.hpp>
#include <vapours/util/util_in_place.hpp>
#include <vapours/util/impl/util_enable_copy_move.hpp>
namespace ams::util {
namespace impl {
class NulloptHelper {
public:
template<typename T>
static consteval T CreateInstance() {
return T(T::ConstructionArgument::Token);
}
};
}
struct nullopt_t {
private:
friend class impl::NulloptHelper;
enum class ConstructionArgument {
Token,
};
public:
consteval nullopt_t(ConstructionArgument) { /* ... */ }
};
constexpr inline nullopt_t nullopt = impl::NulloptHelper::CreateInstance<nullopt_t>();
namespace impl {
template<typename T>
struct OptionalPayloadBase {
using StoredType = typename std::remove_const<T>::type;
struct EmptyType{};
template<typename U, bool = std::is_trivially_destructible<U>::value>
union StorageType {
EmptyType m_empty;
U m_value;
constexpr ALWAYS_INLINE StorageType() : m_empty() { /* ... */ }
template<typename... Args>
constexpr ALWAYS_INLINE StorageType(in_place_t, Args &&... args) : m_value(std::forward<Args>(args)...) { /* ... */ }
template<typename V, typename... Args>
constexpr ALWAYS_INLINE StorageType(std::initializer_list<V> il, Args &&... args) : m_value(il, std::forward<Args>(args)...) { /* ... */ }
};
template<typename U>
union StorageType<U, false> {
EmptyType m_empty;
U m_value;
constexpr ALWAYS_INLINE StorageType() : m_empty() { /* ... */ }
template<typename... Args>
constexpr ALWAYS_INLINE StorageType(in_place_t, Args &&... args) : m_value(std::forward<Args>(args)...) { /* ... */ }
template<typename V, typename... Args>
constexpr ALWAYS_INLINE StorageType(std::initializer_list<V> il, Args &&... args) : m_value(il, std::forward<Args>(args)...) { /* ... */ }
constexpr ALWAYS_INLINE ~StorageType() { /* ... */ }
};
StorageType<StoredType> m_payload;
bool m_engaged = false;
constexpr OptionalPayloadBase() = default;
constexpr ~OptionalPayloadBase() = default;
template<typename... Args>
constexpr OptionalPayloadBase(in_place_t tag, Args &&... args) : m_payload(tag, std::forward<Args>(args)...), m_engaged(true) { /* ... */ }
template<typename U, typename... Args>
constexpr OptionalPayloadBase(std::initializer_list<U> il, Args &&... args) : m_payload(il, std::forward<Args>(args)...), m_engaged(true) { /* ... */ }
constexpr OptionalPayloadBase(bool engaged, const OptionalPayloadBase &rhs) { if (rhs.m_engaged) { this->Construct(rhs.Get()); } }
constexpr OptionalPayloadBase(bool engaged, OptionalPayloadBase &&rhs) { if (rhs.m_engaged) { this->Construct(std::move(rhs.Get())); } }
constexpr OptionalPayloadBase(const OptionalPayloadBase &) = default;
constexpr OptionalPayloadBase(OptionalPayloadBase &&) = default;
constexpr OptionalPayloadBase &operator=(const OptionalPayloadBase &) = default;
constexpr OptionalPayloadBase &operator=(OptionalPayloadBase &&) = default;
constexpr void CopyAssign(const OptionalPayloadBase &rhs) {
if (m_engaged && rhs.m_engaged) {
this->Get() = rhs.Get();
} else if (rhs.m_engaged) {
this->Construct(rhs.Get());
} else {
this->Reset();
}
}
constexpr void MoveAssign(OptionalPayloadBase &&rhs) {
if (m_engaged && rhs.m_engaged) {
this->Get() = std::move(rhs.Get());
} else if (rhs.m_engaged) {
this->Construct(std::move(rhs.Get()));
} else {
this->Reset();
}
}
template<typename... Args>
constexpr void Construct(Args &&... args) {
std::construct_at(std::addressof(m_payload.m_value), std::forward<Args>(args)...);
m_engaged = true;
}
constexpr void Destroy() {
m_engaged = false;
std::destroy_at(std::addressof(m_payload.m_value));
}
constexpr ALWAYS_INLINE T &Get() { return m_payload.m_value; }
constexpr ALWAYS_INLINE const T &Get() const { return m_payload.m_value; }
constexpr void Reset() {
if (m_engaged) {
this->Destroy();
}
}
};
template<typename T, bool = std::is_trivially_destructible<T>::value, bool = std::is_trivially_copy_assignable<T>::value && std::is_trivially_copy_constructible<T>::value, bool = std::is_trivially_move_assignable<T>::value && std::is_trivially_move_constructible<T>::value>
struct OptionalPayload;
template<typename T>
struct OptionalPayload<T, true, true, true> : OptionalPayloadBase<T> {
using OptionalPayloadBase<T>::OptionalPayloadBase;
constexpr OptionalPayload() = default;
};
template<typename T>
struct OptionalPayload<T, true, false, true> : OptionalPayloadBase<T> {
using OptionalPayloadBase<T>::OptionalPayloadBase;
constexpr OptionalPayload() = default;
constexpr ~OptionalPayload() = default;
constexpr OptionalPayload(const OptionalPayload &) = default;
constexpr OptionalPayload(OptionalPayload &&) = default;
constexpr OptionalPayload& operator=(OptionalPayload &&) = default;
constexpr OptionalPayload &operator=(const OptionalPayload &rhs) {
this->CopyAssign(rhs);
return *this;
}
};
template<typename T>
struct OptionalPayload<T, true, true, false> : OptionalPayloadBase<T> {
using OptionalPayloadBase<T>::OptionalPayloadBase;
constexpr OptionalPayload() = default;
constexpr ~OptionalPayload() = default;
constexpr OptionalPayload(const OptionalPayload &) = default;
constexpr OptionalPayload(OptionalPayload &&) = default;
constexpr OptionalPayload& operator=(const OptionalPayload &) = default;
constexpr OptionalPayload &operator=(OptionalPayload &&rhs) {
this->MoveAssign(std::move(rhs));
return *this;
}
};
template<typename T>
struct OptionalPayload<T, true, false, false> : OptionalPayloadBase<T> {
using OptionalPayloadBase<T>::OptionalPayloadBase;
constexpr OptionalPayload() = default;
constexpr ~OptionalPayload() = default;
constexpr OptionalPayload(const OptionalPayload &) = default;
constexpr OptionalPayload(OptionalPayload &&) = default;
constexpr OptionalPayload &operator=(const OptionalPayload &rhs) {
this->CopyAssign(rhs);
return *this;
}
constexpr OptionalPayload &operator=(OptionalPayload &&rhs) {
this->MoveAssign(std::move(rhs));
return *this;
}
};
template<typename T, bool TrivialCopy, bool TrivialMove>
struct OptionalPayload<T, false, TrivialCopy, TrivialMove> : OptionalPayload<T, true, TrivialCopy, TrivialMove> {
using OptionalPayload<T, true, TrivialCopy, TrivialMove>::OptionalPayload;
constexpr OptionalPayload() = default;
constexpr OptionalPayload(const OptionalPayload &) = default;
constexpr OptionalPayload(OptionalPayload &&) = default;
constexpr OptionalPayload& operator=(const OptionalPayload &) = default;
constexpr OptionalPayload& operator=(OptionalPayload &&) = default;
constexpr ~OptionalPayload() { this->Reset(); }
};
template<typename T, typename Derived>
class OptionalBaseImpl {
protected:
using StoredType = std::remove_const<T>::type;
template<typename... Args>
constexpr void ConstructImpl(Args &&... args) { static_cast<Derived *>(this)->m_payload.Construct(std::forward<Args>(args)...); }
constexpr void DestructImpl() { static_cast<Derived *>(this)->m_payload.Destroy(); }
constexpr void ResetImpl() { static_cast<Derived *>(this)->m_payload.Reset(); }
constexpr ALWAYS_INLINE bool IsEngagedImpl() const { return static_cast<const Derived *>(this)->m_payload.m_engaged; }
constexpr ALWAYS_INLINE T &GetImpl() { return static_cast<Derived *>(this)->m_payload.Get(); }
constexpr ALWAYS_INLINE const T &GetImpl() const { return static_cast<const Derived *>(this)->m_payload.Get(); }
};
template<typename T, bool = std::is_trivially_copy_constructible<T>::value, bool = std::is_trivially_move_constructible<T>::value>
struct OptionalBase : OptionalBaseImpl<T, OptionalBase<T>> {
OptionalPayload<T> m_payload;
constexpr OptionalBase() = default;
template<typename... Args, std::enable_if_t<std::is_constructible<T, Args...>::value, bool> = false>
constexpr explicit OptionalBase(in_place_t, Args &&... args) : m_payload(in_place, std::forward<Args>(args)...) { /* ... */ }
template<typename U, typename... Args, std::enable_if_t<std::is_constructible<T, std::initializer_list<U> &, Args...>::value, bool> = false>
constexpr explicit OptionalBase(in_place_t, std::initializer_list<U> il, Args &&... args) : m_payload(in_place, il, std::forward<Args>(args)...) { /* ... */ }
constexpr OptionalBase(const OptionalBase &rhs) : m_payload(rhs.m_payload.m_engaged, rhs.m_payload) { /* ... */ }
constexpr OptionalBase(OptionalBase &&rhs) : m_payload(rhs.m_payload.m_engaged, std::move(rhs.m_payload)) { /* ... */ }
constexpr OptionalBase &operator=(const OptionalBase &) = default;
constexpr OptionalBase &operator=(OptionalBase &&) = default;
};
template<typename T>
struct OptionalBase<T, false, true> : OptionalBaseImpl<T, OptionalBase<T>> {
OptionalPayload<T> m_payload;
constexpr OptionalBase() = default;
template<typename... Args, std::enable_if_t<std::is_constructible<T, Args...>::value, bool> = false>
constexpr explicit OptionalBase(in_place_t, Args &&... args) : m_payload(in_place, std::forward<Args>(args)...) { /* ... */ }
template<typename U, typename... Args, std::enable_if_t<std::is_constructible<T, std::initializer_list<U> &, Args...>::value, bool> = false>
constexpr explicit OptionalBase(in_place_t, std::initializer_list<U> il, Args &&... args) : m_payload(in_place, il, std::forward<Args>(args)...) { /* ... */ }
constexpr OptionalBase(const OptionalBase &rhs) : m_payload(rhs.m_payload.m_engaged, rhs.m_payload) { /* ... */ }
constexpr OptionalBase(OptionalBase &&rhs) = default;
constexpr OptionalBase &operator=(const OptionalBase &) = default;
constexpr OptionalBase &operator=(OptionalBase &&) = default;
};
template<typename T>
struct OptionalBase<T, true, false> : OptionalBaseImpl<T, OptionalBase<T>> {
OptionalPayload<T> m_payload;
constexpr OptionalBase() = default;
template<typename... Args, std::enable_if_t<std::is_constructible<T, Args...>::value, bool> = false>
constexpr explicit OptionalBase(in_place_t, Args &&... args) : m_payload(in_place, std::forward<Args>(args)...) { /* ... */ }
template<typename U, typename... Args, std::enable_if_t<std::is_constructible<T, std::initializer_list<U> &, Args...>::value, bool> = false>
constexpr explicit OptionalBase(in_place_t, std::initializer_list<U> il, Args &&... args) : m_payload(in_place, il, std::forward<Args>(args)...) { /* ... */ }
constexpr OptionalBase(const OptionalBase &rhs) = default;
constexpr OptionalBase(OptionalBase &&rhs) : m_payload(rhs.m_payload.m_engaged, std::move(rhs.m_payload)) { /* ... */ }
constexpr OptionalBase &operator=(const OptionalBase &) = default;
constexpr OptionalBase &operator=(OptionalBase &&) = default;
};
template<typename T>
struct OptionalBase<T, true, true> : OptionalBaseImpl<T, OptionalBase<T>> {
OptionalPayload<T> m_payload;
constexpr OptionalBase() = default;
template<typename... Args, std::enable_if_t<std::is_constructible<T, Args...>::value, bool> = false>
constexpr explicit OptionalBase(in_place_t, Args &&... args) : m_payload(in_place, std::forward<Args>(args)...) { /* ... */ }
template<typename U, typename... Args, std::enable_if_t<std::is_constructible<T, std::initializer_list<U> &, Args...>::value, bool> = false>
constexpr explicit OptionalBase(in_place_t, std::initializer_list<U> il, Args &&... args) : m_payload(in_place, il, std::forward<Args>(args)...) { /* ... */ }
constexpr OptionalBase(const OptionalBase &rhs) = default;
constexpr OptionalBase(OptionalBase &&rhs) = default;
constexpr OptionalBase &operator=(const OptionalBase &) = default;
constexpr OptionalBase &operator=(OptionalBase &&) = default;
};
}
template<typename T>
class optional;
namespace impl {
template<typename T, typename U>
constexpr inline bool ConvertsFromOptional = std::is_constructible<T, const optional<U> &>::value ||
std::is_constructible<T, optional<U> &>::value ||
std::is_constructible<T, const optional<U> &&>::value ||
std::is_constructible<T, optional<U> &&>::value ||
std::is_convertible<const optional<U> &, T>::value ||
std::is_convertible<optional<U> &, T>::value ||
std::is_convertible<const optional<U> &&, T>::value ||
std::is_convertible<optional<U> &&, T>::value;
template<typename T, typename U>
constexpr inline bool AssignsFromOptional = std::is_assignable<T &, const optional<U> &>::value ||
std::is_assignable<T &, optional<U> &>::value ||
std::is_assignable<T &, const optional<U> &&>::value ||
std::is_assignable<T &, optional<U> &&>::value;
}
template<typename T>
class optional : private impl::OptionalBase<T>, private impl::EnableCopyMove<std::is_copy_constructible<T>::value, std::is_copy_constructible<T>::value && std::is_copy_assignable<T>::value, std::is_move_constructible<T>::value, std::is_move_constructible<T>::value && std::is_move_assignable<T>::value, optional<T>> {
static_assert(!std::is_same<std::remove_cv_t<T>, ::ams::util::nullopt_t>::value);
static_assert(!std::is_same<std::remove_cv_t<T>, ::ams::util::in_place_t>::value);
static_assert(!std::is_reference<T>::value);
private:
using Base = impl::OptionalBase<T>;
template<typename U> static constexpr inline bool IsNotSelf = !std::is_same<optional, std::remove_cvref_t<U>>::value;
template<typename U> static constexpr inline bool IsNotTag = !std::is_same<::ams::util::in_place_t, std::remove_cvref_t<U>>::value && !std::is_same<::std::in_place_t, std::remove_cvref_t<U>>::value;
template<bool... Cond>
using Requires = std::enable_if_t<(Cond && ...), bool>;
public:
using value_type = T;
public:
constexpr optional() { /* ... */ }
constexpr optional(nullopt_t) { /* ... */ }
template<typename U = T, Requires<IsNotSelf<U>, IsNotTag<U>, std::is_constructible<T, U>::value, std::is_convertible<U, T>::value> = true>
constexpr optional(U &&u) : Base(::ams::util::in_place, std::forward<U>(u)) { /* ... */ }
template<typename U = T, Requires<IsNotSelf<U>, IsNotTag<U>, std::is_constructible<T, U>::value, !std::is_convertible<U, T>::value> = false>
constexpr explicit optional(U &&u) : Base(::ams::util::in_place, std::forward<U>(u)) { /* ... */ }
template<typename U, Requires<!std::is_same<T, U>::value, std::is_constructible<T, const U &>::value, std::is_convertible<const U &, T>::value, !impl::ConvertsFromOptional<T, U>> = true>
constexpr optional(const optional<U> &u) {
if (u) {
this->emplace(*u);
}
}
template<typename U, Requires<!std::is_same<T, U>::value, std::is_constructible<T, const U &>::value, !std::is_convertible<const U &, T>::value, !impl::ConvertsFromOptional<T, U>> = false>
constexpr explicit optional(const optional<U> &u) {
if (u) {
this->emplace(*u);
}
}
template<typename U, Requires<!std::is_same<T, U>::value, std::is_constructible<T, const U &>::value, std::is_convertible<const U &, T>::value, !impl::ConvertsFromOptional<T, U>> = true>
constexpr optional(optional<U> &&u) {
if (u) {
this->emplace(std::move(*u));
}
}
template<typename U, Requires<!std::is_same<T, U>::value, std::is_constructible<T, const U &>::value, !std::is_convertible<const U &, T>::value, !impl::ConvertsFromOptional<T, U>> = false>
constexpr explicit optional(optional<U> &&u) {
if (u) {
this->emplace(std::move(*u));
}
}
template<typename... Args, Requires<std::is_constructible<T, Args...>::value> = false>
constexpr explicit optional(in_place_t, Args &&... args) : Base(::ams::util::in_place, std::forward<Args>(args)...) { /* ... */ }
template<typename U, typename... Args, Requires<std::is_constructible<T, std::initializer_list<U> &, Args...>::value> = false>
constexpr explicit optional(in_place_t, std::initializer_list<U> il, Args &&... args) : Base(::ams::util::in_place, il, std::forward<Args>(args)...) { /* ... */ }
constexpr optional &operator=(nullopt_t) { this->ResetImpl(); return *this; }
template<typename U = T>
constexpr std::enable_if_t<IsNotSelf<U> && !(std::is_scalar<T>::value && std::is_same<T, std::decay_t<U>>::value) && std::is_constructible<T, U>::value && std::is_assignable<T &, U>::value,
optional &>
operator =(U &&u) {
if (this->IsEngagedImpl()) {
this->GetImpl() = std::forward<U>(u);
} else {
this->ConstructImpl(std::forward<U>(u));
}
return *this;
}
template<typename U>
constexpr std::enable_if_t<!std::is_same<T, U>::value && std::is_constructible<T, const U &>::value && std::is_assignable<T &, const U &>::value && !impl::ConvertsFromOptional<T, U> && !impl::AssignsFromOptional<T, U>,
optional &>
operator =(const optional<U> &u) {
if (u) {
if (this->IsEngagedImpl()) {
this->GetImpl() = *u;
} else {
this->ConstructImpl(*u);
}
} else {
this->ResetImpl();
}
return *this;
}
template<typename U>
constexpr std::enable_if_t<!std::is_same<T, U>::value && std::is_constructible<T, U>::value && std::is_assignable<T &, U>::value && !impl::ConvertsFromOptional<T, U> && !impl::AssignsFromOptional<T, U>,
optional &>
operator =(optional<U> &&u) {
if (u) {
if (this->IsEngagedImpl()) {
this->GetImpl() = std::move(*u);
} else {
this->ConstructImpl(std::move(*u));
}
} else {
this->ResetImpl();
}
return *this;
}
template<typename... Args>
constexpr std::enable_if_t<std::is_constructible<T, Args...>::value, T &> emplace(Args &&... args) {
this->ResetImpl();
this->ConstructImpl(std::forward<Args>(args)...);
return this->GetImpl();
}
template<typename U, typename... Args>
constexpr std::enable_if_t<std::is_constructible<T, std::initializer_list<U> &, Args...>::value, T &> emplace(std::initializer_list<U> il, Args &&... args) {
this->ResetImpl();
this->ConstructImpl(il, std::forward<Args>(args)...);
return this->GetImpl();
}
constexpr void swap(optional &rhs) {
if (this->IsEngagedImpl() && rhs.IsEngagedImpl()) {
std::swap(this->GetImpl(), rhs.GetImpl());
} else if (this->IsEngagedImpl()) {
rhs.ConstructImpl(std::move(this->GetImpl()));
this->DestructImpl();
} else if (rhs.IsEngagedImpl()) {
this->ConstructImpl(std::move(rhs.GetImpl()));
rhs.DestructImpl();
}
}
constexpr ALWAYS_INLINE const T *operator ->() const { return std::addressof(this->GetImpl()); }
constexpr ALWAYS_INLINE T *operator ->() { return std::addressof(this->GetImpl()); }
constexpr ALWAYS_INLINE const T &operator *() const & { return this->GetImpl(); }
constexpr ALWAYS_INLINE T &operator *() & { return this->GetImpl(); }
constexpr ALWAYS_INLINE const T &&operator *() const && { return std::move(this->GetImpl()); }
constexpr ALWAYS_INLINE T &&operator *() && { return std::move(this->GetImpl()); }
constexpr ALWAYS_INLINE explicit operator bool() const { return this->IsEngagedImpl(); }
constexpr ALWAYS_INLINE bool has_value() const { return this->IsEngagedImpl(); }
constexpr ALWAYS_INLINE const T &value() const & { /* AMS_ASSERT(this->IsEngagedImpl()); */ return this->GetImpl(); }
constexpr ALWAYS_INLINE T &value() & { /* AMS_ASSERT(this->IsEngagedImpl()); */ return this->GetImpl(); }
constexpr ALWAYS_INLINE const T &&value() const && { /* AMS_ASSERT(this->IsEngagedImpl()); */ return std::move(this->GetImpl()); }
constexpr ALWAYS_INLINE T &&value() && { /* AMS_ASSERT(this->IsEngagedImpl()); */ return std::move(this->GetImpl()); }
template<typename U>
constexpr T value_or(U &&u) const & {
static_assert(std::is_copy_constructible<T>::value);
static_assert(std::is_convertible<U &&, T>::value);
return this->IsEngagedImpl() ? this->GetImpl() : static_cast<T>(std::forward<U>(u));
}
template<typename U>
constexpr T value_or(U &&u) && {
static_assert(std::is_move_constructible<T>::value);
static_assert(std::is_convertible<U &&, T>::value);
return this->IsEngagedImpl() ? std::move(this->GetImpl()) : static_cast<T>(std::forward<U>(u));
}
constexpr void reset() { this->ResetImpl(); }
};
namespace impl {
template<typename T> using optional_relop_t = std::enable_if_t<std::is_convertible<T, bool>::value, bool>;
template<typename T, typename U> using optional_eq_t = optional_relop_t<decltype(std::declval<const T &>() == std::declval<const U &>())>;
template<typename T, typename U> using optional_ne_t = optional_relop_t<decltype(std::declval<const T &>() != std::declval<const U &>())>;
template<typename T, typename U> using optional_le_t = optional_relop_t<decltype(std::declval<const T &>() <= std::declval<const U &>())>;
template<typename T, typename U> using optional_ge_t = optional_relop_t<decltype(std::declval<const T &>() >= std::declval<const U &>())>;
template<typename T, typename U> using optional_lt_t = optional_relop_t<decltype(std::declval<const T &>() < std::declval<const U &>())>;
template<typename T, typename U> using optional_gt_t = optional_relop_t<decltype(std::declval<const T &>() > std::declval<const U &>())>;
}
template<typename T, typename U>
constexpr inline impl::optional_eq_t<T, U> operator==(const optional<T> &lhs, const optional<U> &rhs) { return static_cast<bool>(lhs) == static_cast<bool>(rhs) && (!lhs || *lhs == *rhs); }
template<typename T, typename U>
constexpr inline impl::optional_ne_t<T, U> operator!=(const optional<T> &lhs, const optional<U> &rhs) { return static_cast<bool>(lhs) != static_cast<bool>(rhs) || (static_cast<bool>(lhs) && *lhs != *rhs); }
template<typename T, typename U>
constexpr inline impl::optional_lt_t<T, U> operator< (const optional<T> &lhs, const optional<U> &rhs) { return static_cast<bool>(rhs) && (!lhs || *lhs < *rhs); }
template<typename T, typename U>
constexpr inline impl::optional_gt_t<T, U> operator> (const optional<T> &lhs, const optional<U> &rhs) { return static_cast<bool>(lhs) && (!rhs || *lhs > *rhs); }
template<typename T, typename U>
constexpr inline impl::optional_le_t<T, U> operator<=(const optional<T> &lhs, const optional<U> &rhs) { return !lhs || (static_cast<bool>(rhs) && *lhs <= *rhs); }
template<typename T, typename U>
constexpr inline impl::optional_ge_t<T, U> operator>=(const optional<T> &lhs, const optional<U> &rhs) { return !rhs || (static_cast<bool>(lhs) && *lhs >= *rhs); }
template<typename T, std::three_way_comparable_with<T> U>
constexpr inline std::compare_three_way_result_t<T, U> operator <=>(const optional<T> &lhs, const optional<U> &rhs) {
return (lhs && rhs) ? *lhs <=> *rhs : static_cast<bool>(lhs) <=> static_cast<bool>(rhs);
}
template<typename T> constexpr inline bool operator==(const optional<T> &lhs, nullopt_t) { return !lhs; }
template<typename T> constexpr inline std::strong_ordering operator<=>(const optional<T> &lhs, nullopt_t) { return static_cast<bool>(lhs) <=> false; }
template<typename T, typename U>
constexpr inline impl::optional_eq_t<T, U> operator==(const optional<T> &lhs, const U &rhs) { return lhs && *lhs == rhs; }
template<typename T, typename U>
constexpr inline impl::optional_eq_t<U, T> operator==(const U &lhs, const optional<T> &rhs) { return rhs && lhs == *rhs; }
template<typename T, typename U>
constexpr inline impl::optional_ne_t<T, U> operator!=(const optional<T> &lhs, const U &rhs) { return !lhs || *lhs != rhs; }
template<typename T, typename U>
constexpr inline impl::optional_ne_t<U, T> operator!=(const U &lhs, const optional<T> &rhs) { return !rhs || lhs != *rhs; }
template<typename T, typename U>
constexpr inline impl::optional_lt_t<T, U> operator< (const optional<T> &lhs, const U &rhs) { return !lhs || *lhs < rhs; }
template<typename T, typename U>
constexpr inline impl::optional_lt_t<U, T> operator< (const U &lhs, const optional<T> &rhs) { return rhs && lhs < *rhs; }
template<typename T, typename U>
constexpr inline impl::optional_gt_t<T, U> operator> (const optional<T> &lhs, const U &rhs) { return lhs && *lhs > rhs; }
template<typename T, typename U>
constexpr inline impl::optional_gt_t<U, T> operator> (const U &lhs, const optional<T> &rhs) { return !rhs || lhs > *rhs; }
template<typename T, typename U>
constexpr inline impl::optional_le_t<T, U> operator<=(const optional<T> &lhs, const U &rhs) { return !lhs || *lhs <= rhs; }
template<typename T, typename U>
constexpr inline impl::optional_le_t<U, T> operator<=(const U &lhs, const optional<T> &rhs) { return rhs && lhs <= *rhs; }
template<typename T, typename U>
constexpr inline impl::optional_ge_t<T, U> operator>=(const optional<T> &lhs, const U &rhs) { return lhs && *lhs >= rhs; }
template<typename T, typename U>
constexpr inline impl::optional_ge_t<U, T> operator>=(const U &lhs, const optional<T> &rhs) { return !rhs || lhs >= *rhs; }
namespace impl {
template<typename T>
constexpr inline bool IsOptional = false;
template<typename T>
constexpr inline bool IsOptional<optional<T>> = true;
}
template<typename T, typename U> requires (!impl::IsOptional<U>) && std::three_way_comparable_with<T, U>
constexpr inline std::compare_three_way_result_t<T, U> operator<=>(const optional<T> &lhs, const U &rhs) {
return static_cast<bool>(lhs) ? *lhs <=> rhs : std::strong_ordering::less;
}
template<typename T>
constexpr inline std::enable_if_t<std::is_constructible<std::decay_t<T>, T>::value, optional<std::decay_t<T>>> make_optional(T && t) { return optional<std::decay_t<T>>{ std::forward<T>(t) }; }
template<typename T, typename... Args>
constexpr inline std::enable_if_t<std::is_constructible<T, Args...>::value, optional<T>> make_optional(Args &&... args) { return optional<T>{ ::ams::util::in_place, std::forward<Args>(args)... }; }
template<typename T, typename U, typename... Args>
constexpr inline std::enable_if_t<std::is_constructible<T, std::initializer_list<U> &, Args...>::value, optional<T>> make_optional(std::initializer_list<U> il, Args &&... args) { return optional<T>{ ::ams::util::in_place, il, std::forward<Args>(args)... }; }
template<typename T> optional(T) -> optional<T>;
}
namespace std {
template<typename T>
constexpr inline enable_if_t<is_move_constructible_v<T> && is_swappable_v<T>> swap(::ams::util::optional<T> &lhs, ::ams::util::optional<T> &rhs) noexcept {
lhs.swap(rhs);
}
template<typename T>
constexpr inline enable_if_t<!(is_move_constructible_v<T> && is_swappable_v<T>)> swap(::ams::util::optional<T> &lhs, ::ams::util::optional<T> &rhs) = delete;
}