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-rw-r--r--common/aloptional.h344
1 files changed, 4 insertions, 340 deletions
diff --git a/common/aloptional.h b/common/aloptional.h
index 6de16799..45b0cf8a 100644
--- a/common/aloptional.h
+++ b/common/aloptional.h
@@ -1,353 +1,17 @@
#ifndef AL_OPTIONAL_H
#define AL_OPTIONAL_H
-#include <initializer_list>
-#include <type_traits>
-#include <utility>
-
-#include "almalloc.h"
+#include <optional>
namespace al {
-struct nullopt_t { };
-struct in_place_t { };
-
-constexpr nullopt_t nullopt{};
-constexpr in_place_t in_place{};
-
-#define NOEXCEPT_AS(...) noexcept(noexcept(__VA_ARGS__))
-
-namespace detail_ {
-/* Base storage struct for an optional. Defines a trivial destructor, for types
- * that can be trivially destructed.
- */
-template<typename T, bool = std::is_trivially_destructible<T>::value>
-struct optstore_base {
- bool mHasValue{false};
- union {
- char mDummy{};
- T mValue;
- };
-
- constexpr optstore_base() noexcept { }
- template<typename ...Args>
- constexpr explicit optstore_base(in_place_t, Args&& ...args)
- noexcept(std::is_nothrow_constructible<T, Args...>::value)
- : mHasValue{true}, mValue{std::forward<Args>(args)...}
- { }
- ~optstore_base() = default;
-};
-
-/* Specialization needing a non-trivial destructor. */
-template<typename T>
-struct optstore_base<T, false> {
- bool mHasValue{false};
- union {
- char mDummy{};
- T mValue;
- };
-
- constexpr optstore_base() noexcept { }
- template<typename ...Args>
- constexpr explicit optstore_base(in_place_t, Args&& ...args)
- noexcept(std::is_nothrow_constructible<T, Args...>::value)
- : mHasValue{true}, mValue{std::forward<Args>(args)...}
- { }
- ~optstore_base() { if(mHasValue) al::destroy_at(std::addressof(mValue)); }
-};
-
-/* Next level of storage, which defines helpers to construct and destruct the
- * stored object.
- */
-template<typename T>
-struct optstore_helper : public optstore_base<T> {
- using optstore_base<T>::optstore_base;
-
- template<typename... Args>
- constexpr void construct(Args&& ...args) noexcept(std::is_nothrow_constructible<T, Args...>::value)
- {
- al::construct_at(std::addressof(this->mValue), std::forward<Args>(args)...);
- this->mHasValue = true;
- }
-
- constexpr void reset() noexcept
- {
- if(this->mHasValue)
- al::destroy_at(std::addressof(this->mValue));
- this->mHasValue = false;
- }
-
- constexpr void assign(const optstore_helper &rhs)
- noexcept(std::is_nothrow_copy_constructible<T>::value
- && std::is_nothrow_copy_assignable<T>::value)
- {
- if(!rhs.mHasValue)
- this->reset();
- else if(this->mHasValue)
- this->mValue = rhs.mValue;
- else
- this->construct(rhs.mValue);
- }
-
- constexpr void assign(optstore_helper&& rhs)
- noexcept(std::is_nothrow_move_constructible<T>::value
- && std::is_nothrow_move_assignable<T>::value)
- {
- if(!rhs.mHasValue)
- this->reset();
- else if(this->mHasValue)
- this->mValue = std::move(rhs.mValue);
- else
- this->construct(std::move(rhs.mValue));
- }
-};
-
-/* Define copy and move constructors and assignment operators, which may or may
- * not be trivial.
- */
-template<typename T, bool trivial_copy = std::is_trivially_copy_constructible<T>::value,
- bool trivial_move = std::is_trivially_move_constructible<T>::value,
- /* Trivial assignment is dependent on trivial construction+destruction. */
- bool = trivial_copy && std::is_trivially_copy_assignable<T>::value
- && std::is_trivially_destructible<T>::value,
- bool = trivial_move && std::is_trivially_move_assignable<T>::value
- && std::is_trivially_destructible<T>::value>
-struct optional_storage;
-
-/* Some versions of GCC have issues with 'this' in the following noexcept(...)
- * statements, so this macro is a workaround.
- */
-#define _this std::declval<optional_storage*>()
-
-/* Completely trivial. */
-template<typename T>
-struct optional_storage<T, true, true, true, true> : public optstore_helper<T> {
- using optstore_helper<T>::optstore_helper;
- constexpr optional_storage() noexcept = default;
- constexpr optional_storage(const optional_storage&) = default;
- constexpr optional_storage(optional_storage&&) = default;
- constexpr optional_storage& operator=(const optional_storage&) = default;
- constexpr optional_storage& operator=(optional_storage&&) = default;
-};
-
-/* Non-trivial move assignment. */
-template<typename T>
-struct optional_storage<T, true, true, true, false> : public optstore_helper<T> {
- using optstore_helper<T>::optstore_helper;
- constexpr optional_storage() noexcept = default;
- constexpr optional_storage(const optional_storage&) = default;
- constexpr optional_storage(optional_storage&&) = default;
- constexpr optional_storage& operator=(const optional_storage&) = default;
- constexpr optional_storage& operator=(optional_storage&& rhs) NOEXCEPT_AS(_this->assign(std::move(rhs)))
- { this->assign(std::move(rhs)); return *this; }
-};
-
-/* Non-trivial move construction. */
-template<typename T>
-struct optional_storage<T, true, false, true, false> : public optstore_helper<T> {
- using optstore_helper<T>::optstore_helper;
- constexpr optional_storage() noexcept = default;
- constexpr optional_storage(const optional_storage&) = default;
- constexpr optional_storage(optional_storage&& rhs) NOEXCEPT_AS(_this->construct(std::move(rhs.mValue)))
- { if(rhs.mHasValue) this->construct(std::move(rhs.mValue)); }
- constexpr optional_storage& operator=(const optional_storage&) = default;
- constexpr optional_storage& operator=(optional_storage&& rhs) NOEXCEPT_AS(_this->assign(std::move(rhs)))
- { this->assign(std::move(rhs)); return *this; }
-};
-
-/* Non-trivial copy assignment. */
-template<typename T>
-struct optional_storage<T, true, true, false, true> : public optstore_helper<T> {
- using optstore_helper<T>::optstore_helper;
- constexpr optional_storage() noexcept = default;
- constexpr optional_storage(const optional_storage&) = default;
- constexpr optional_storage(optional_storage&&) = default;
- constexpr optional_storage& operator=(const optional_storage &rhs) NOEXCEPT_AS(_this->assign(rhs))
- { this->assign(rhs); return *this; }
- constexpr optional_storage& operator=(optional_storage&&) = default;
-};
-
-/* Non-trivial copy construction. */
-template<typename T>
-struct optional_storage<T, false, true, false, true> : public optstore_helper<T> {
- using optstore_helper<T>::optstore_helper;
- constexpr optional_storage() noexcept = default;
- constexpr optional_storage(const optional_storage &rhs) NOEXCEPT_AS(_this->construct(rhs.mValue))
- { if(rhs.mHasValue) this->construct(rhs.mValue); }
- constexpr optional_storage(optional_storage&&) = default;
- constexpr optional_storage& operator=(const optional_storage &rhs) NOEXCEPT_AS(_this->assign(rhs))
- { this->assign(rhs); return *this; }
- constexpr optional_storage& operator=(optional_storage&&) = default;
-};
-
-/* Non-trivial assignment. */
-template<typename T>
-struct optional_storage<T, true, true, false, false> : public optstore_helper<T> {
- using optstore_helper<T>::optstore_helper;
- constexpr optional_storage() noexcept = default;
- constexpr optional_storage(const optional_storage&) = default;
- constexpr optional_storage(optional_storage&&) = default;
- constexpr optional_storage& operator=(const optional_storage &rhs) NOEXCEPT_AS(_this->assign(rhs))
- { this->assign(rhs); return *this; }
- constexpr optional_storage& operator=(optional_storage&& rhs) NOEXCEPT_AS(_this->assign(std::move(rhs)))
- { this->assign(std::move(rhs)); return *this; }
-};
-
-/* Non-trivial assignment, non-trivial move construction. */
-template<typename T>
-struct optional_storage<T, true, false, false, false> : public optstore_helper<T> {
- using optstore_helper<T>::optstore_helper;
- constexpr optional_storage() noexcept = default;
- constexpr optional_storage(const optional_storage&) = default;
- constexpr optional_storage(optional_storage&& rhs) NOEXCEPT_AS(_this->construct(std::move(rhs.mValue)))
- { if(rhs.mHasValue) this->construct(std::move(rhs.mValue)); }
- constexpr optional_storage& operator=(const optional_storage &rhs) NOEXCEPT_AS(_this->assign(rhs))
- { this->assign(rhs); return *this; }
- constexpr optional_storage& operator=(optional_storage&& rhs) NOEXCEPT_AS(_this->assign(std::move(rhs)))
- { this->assign(std::move(rhs)); return *this; }
-};
-
-/* Non-trivial assignment, non-trivial copy construction. */
-template<typename T>
-struct optional_storage<T, false, true, false, false> : public optstore_helper<T> {
- using optstore_helper<T>::optstore_helper;
- constexpr optional_storage() noexcept = default;
- constexpr optional_storage(const optional_storage &rhs) NOEXCEPT_AS(_this->construct(rhs.mValue))
- { if(rhs.mHasValue) this->construct(rhs.mValue); }
- constexpr optional_storage(optional_storage&&) = default;
- constexpr optional_storage& operator=(const optional_storage &rhs) NOEXCEPT_AS(_this->assign(rhs))
- { this->assign(rhs); return *this; }
- constexpr optional_storage& operator=(optional_storage&& rhs) NOEXCEPT_AS(_this->assign(std::move(rhs)))
- { this->assign(std::move(rhs)); return *this; }
-};
+constexpr auto nullopt = std::nullopt;
-/* Completely non-trivial. */
template<typename T>
-struct optional_storage<T, false, false, false, false> : public optstore_helper<T> {
- using optstore_helper<T>::optstore_helper;
- constexpr optional_storage() noexcept = default;
- constexpr optional_storage(const optional_storage &rhs) NOEXCEPT_AS(_this->construct(rhs.mValue))
- { if(rhs.mHasValue) this->construct(rhs.mValue); }
- constexpr optional_storage(optional_storage&& rhs) NOEXCEPT_AS(_this->construct(std::move(rhs.mValue)))
- { if(rhs.mHasValue) this->construct(std::move(rhs.mValue)); }
- constexpr optional_storage& operator=(const optional_storage &rhs) NOEXCEPT_AS(_this->assign(rhs))
- { this->assign(rhs); return *this; }
- constexpr optional_storage& operator=(optional_storage&& rhs) NOEXCEPT_AS(_this->assign(std::move(rhs)))
- { this->assign(std::move(rhs)); return *this; }
-};
-
-#undef _this
-
-} // namespace detail_
-
-#define REQUIRES(...) std::enable_if_t<(__VA_ARGS__),bool> = true
-
-template<typename T>
-class optional {
- using storage_t = detail_::optional_storage<T>;
-
- storage_t mStore{};
-
-public:
- using value_type = T;
-
- constexpr optional() = default;
- constexpr optional(const optional&) = default;
- constexpr optional(optional&&) = default;
- constexpr optional(nullopt_t) noexcept { }
- template<typename ...Args>
- constexpr explicit optional(in_place_t, Args&& ...args)
- NOEXCEPT_AS(storage_t{al::in_place, std::forward<Args>(args)...})
- : mStore{al::in_place, std::forward<Args>(args)...}
- { }
- template<typename U, REQUIRES(std::is_constructible<T, U&&>::value
- && !std::is_same<std::decay_t<U>, al::in_place_t>::value
- && !std::is_same<std::decay_t<U>, optional<T>>::value
- && std::is_convertible<U&&, T>::value)>
- constexpr optional(U&& rhs) NOEXCEPT_AS(storage_t{al::in_place, std::forward<U>(rhs)})
- : mStore{al::in_place, std::forward<U>(rhs)}
- { }
- template<typename U, REQUIRES(std::is_constructible<T, U&&>::value
- && !std::is_same<std::decay_t<U>, al::in_place_t>::value
- && !std::is_same<std::decay_t<U>, optional<T>>::value
- && !std::is_convertible<U&&, T>::value)>
- constexpr explicit optional(U&& rhs) NOEXCEPT_AS(storage_t{al::in_place, std::forward<U>(rhs)})
- : mStore{al::in_place, std::forward<U>(rhs)}
- { }
- ~optional() = default;
-
- constexpr optional& operator=(const optional&) = default;
- constexpr optional& operator=(optional&&) = default;
- constexpr optional& operator=(nullopt_t) noexcept { mStore.reset(); return *this; }
- template<typename U=T>
- constexpr std::enable_if_t<std::is_constructible<T, U>::value
- && std::is_assignable<T&, U>::value
- && !std::is_same<std::decay_t<U>, optional<T>>::value
- && (!std::is_same<std::decay_t<U>, T>::value || !std::is_scalar<U>::value),
- optional&> operator=(U&& rhs)
- {
- if(mStore.mHasValue)
- mStore.mValue = std::forward<U>(rhs);
- else
- mStore.construct(std::forward<U>(rhs));
- return *this;
- }
-
- constexpr const T* operator->() const { return std::addressof(mStore.mValue); }
- constexpr T* operator->() { return std::addressof(mStore.mValue); }
- constexpr const T& operator*() const& { return mStore.mValue; }
- constexpr T& operator*() & { return mStore.mValue; }
- constexpr const T&& operator*() const&& { return std::move(mStore.mValue); }
- constexpr T&& operator*() && { return std::move(mStore.mValue); }
-
- constexpr explicit operator bool() const noexcept { return mStore.mHasValue; }
- constexpr bool has_value() const noexcept { return mStore.mHasValue; }
-
- constexpr T& value() & { return mStore.mValue; }
- constexpr const T& value() const& { return mStore.mValue; }
- constexpr T&& value() && { return std::move(mStore.mValue); }
- constexpr const T&& value() const&& { return std::move(mStore.mValue); }
-
- template<typename U>
- constexpr T value_or(U&& defval) const&
- { return bool(*this) ? **this : static_cast<T>(std::forward<U>(defval)); }
- template<typename U>
- constexpr T value_or(U&& defval) &&
- { return bool(*this) ? std::move(**this) : static_cast<T>(std::forward<U>(defval)); }
-
- template<typename ...Args>
- constexpr T& emplace(Args&& ...args)
- {
- mStore.reset();
- mStore.construct(std::forward<Args>(args)...);
- return mStore.mValue;
- }
- 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)
- {
- mStore.reset();
- mStore.construct(il, std::forward<Args>(args)...);
- return mStore.mValue;
- }
-
- constexpr void reset() noexcept { mStore.reset(); }
-};
-
-template<typename T>
-constexpr optional<std::decay_t<T>> make_optional(T&& arg)
-{ return optional<std::decay_t<T>>{in_place, std::forward<T>(arg)}; }
-
-template<typename T, typename... Args>
-constexpr optional<T> make_optional(Args&& ...args)
-{ return optional<T>{in_place, std::forward<Args>(args)...}; }
+using optional = std::optional<T>;
-template<typename T, typename U, typename... Args>
-constexpr optional<T> make_optional(std::initializer_list<U> il, Args&& ...args)
-{ return optional<T>{in_place, il, std::forward<Args>(args)...}; }
+using std::make_optional;
-#undef REQUIRES
-#undef NOEXCEPT_AS
} // namespace al
#endif /* AL_OPTIONAL_H */
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-02 02:30:32 +0000