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COPYING
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304
optional.hpp
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304
optional.hpp
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///
|
||||
// optional - An implementation of std::optional with extensions
|
||||
// Written in 2017 by Simon Brand (@TartanLlama)
|
||||
//
|
||||
// To the extent possible under law, the author(s) have dedicated all
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// copyright and related and neighboring rights to this software to the
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// public domain worldwide. This software is distributed without any warranty.
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//
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// You should have received a copy of the CC0 Public Domain Dedication
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// along with this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
|
||||
///
|
||||
|
||||
#include <type_traits>
|
||||
#include "tl/type_traits.hpp"
|
||||
|
||||
namespace tl {
|
||||
// [optional.optional], class template optional
|
||||
template <class T>
|
||||
class optional;
|
||||
|
||||
// [optional.nullopt], no-value state indicator
|
||||
struct nullopt_t{};
|
||||
inline constexpr nullopt_t nullopt;
|
||||
|
||||
// [optional.bad.access], class bad_optional_access
|
||||
class bad_optional_access : public std::exception {
|
||||
bad_optional_access() = default;
|
||||
const char* what() const {
|
||||
return "Optional has no value";
|
||||
}
|
||||
};
|
||||
|
||||
// [optional.relops], relational operators
|
||||
template <class T, class U>
|
||||
inline constexpr bool operator==(const optional<T>& lhs, const optional<U>& rhs) {
|
||||
if (lhs.has_value() != rhs.has_value())
|
||||
return false;
|
||||
if (lhs.has_value())
|
||||
return true;
|
||||
|
||||
return lhs.value() == rhs.value();
|
||||
}
|
||||
template <class T, class U>
|
||||
inline constexpr bool operator!=(const optional<T>& lhs, const optional<U>& rhs) {
|
||||
if (lhs.has_value() != rhs.has_value())
|
||||
return true;
|
||||
if (lhs.has_value())
|
||||
return false;
|
||||
|
||||
return lhs.value() != rhs.value();
|
||||
}
|
||||
template <class T, class U>
|
||||
inline constexpr bool operator<(const optional<T>& lhs, const optional<U>& rhs) {
|
||||
if (!rhs.has_value())
|
||||
return false;
|
||||
if (!lhs.has_value())
|
||||
return true;
|
||||
|
||||
return lhs.value() < rhs.value();
|
||||
}
|
||||
template <class T, class U>
|
||||
inline constexpr bool operator>(const optional<T>& lhs, const optional<U>& rhs) {
|
||||
if (!lhs.has_value())
|
||||
return false;
|
||||
if (!rhs.has_value())
|
||||
return true;
|
||||
|
||||
return lhs.value() > rhs.value();
|
||||
}
|
||||
template <class T, class U>
|
||||
inline constexpr bool operator<=(const optional<T>& lhs, const optional<U>& rhs) {
|
||||
if (!lhs.has_value())
|
||||
return true;
|
||||
if (!rhs.has_value())
|
||||
return false;
|
||||
|
||||
return lhs.value() <= rhs.value();
|
||||
}
|
||||
}
|
||||
template <class T, class U>
|
||||
inline constexpr bool operator>=(const optional<T>& lhs, const optional<U>& rhs) {
|
||||
if (!rhs.has_value())
|
||||
return true;
|
||||
if (!lhs.has_value())
|
||||
return false;
|
||||
|
||||
return lhs.value() >= rhs.value();
|
||||
}
|
||||
|
||||
// [optional.nullops], comparison with nullopt
|
||||
template <class T> inline constexpr bool operator==(const optional<T>& lhs, nullopt_t) noexcept {
|
||||
return !lhs.has_value();
|
||||
}
|
||||
template <class T> inline constexpr bool operator==(nullopt_t, const optional<T>& rhs) noexcept {
|
||||
return !rhs.has_value();
|
||||
}
|
||||
template <class T> inline constexpr bool operator!=(const optional<T>& lhs, nullopt_t) noexcept {
|
||||
return lhs.has_value();
|
||||
}
|
||||
template <class T> inline constexpr bool operator!=(nullopt_t, const optional<T>& rhs) noexcept {
|
||||
return rhs.has_value();
|
||||
}
|
||||
template <class T> inline constexpr bool operator<(const optional<T>&, nullopt_t) noexcept {
|
||||
return false;
|
||||
}
|
||||
template <class T> inline constexpr bool operator<(nullopt_t, const optional<T>& rhs) noexcept {
|
||||
return rhs.has_value();
|
||||
}
|
||||
template <class T> inline constexpr bool operator<=(const optional<T>& lhs, nullopt_t) noexcept {
|
||||
return !lhs.has_value();
|
||||
}
|
||||
template <class T> inline constexpr bool operator<=(nullopt_t, const optional<T>&) noexcept {
|
||||
return true;
|
||||
}
|
||||
template <class T> inline constexpr bool operator>(const optional<T>& lhs, nullopt_t) noexcept {
|
||||
return lhs.has_value();
|
||||
}
|
||||
template <class T> inline constexpr bool operator>(nullopt_t, const optional<T>&) noexcept {
|
||||
return false;
|
||||
}
|
||||
template <class T> inline constexpr bool operator>=(const optional<T>&, nullopt_t) noexcept {
|
||||
return true;
|
||||
}
|
||||
template <class T> inline constexpr bool operator>=(nullopt_t, const optional<T>& rhs) noexcept {
|
||||
return !rhs.has_value();
|
||||
}
|
||||
|
||||
// [optional.comp_with_t], comparison with T
|
||||
template <class T, class U> inline constexpr bool operator==(const optional<T>& lhs, const U& rhs) {
|
||||
return lhs.has_value() ? *lhs == rhs : false;
|
||||
}
|
||||
template <class T, class U> inline constexpr bool operator==(const U& lhs, const optional<T>& rhs) {
|
||||
return rhs.has_value() ? lhs == rhs.value() : false;
|
||||
}
|
||||
template <class T, class U> inline constexpr bool operator!=(const optional<T>& lhs, const U& rhs) {
|
||||
return lhs.has_value() ? lhs.value() != lhs : true;
|
||||
}
|
||||
template <class T, class U> inline constexpr bool operator!=(const U& lhs, const optional<T>& rhs) {
|
||||
return rhs.has_value() ? lhs != rhs.value() : true;
|
||||
}
|
||||
template <class T, class U> inline constexpr bool operator<(const optional<T>& lhs, const U& rhs) {
|
||||
return lhs.has_value() ? lhs.value() < lhs : true;
|
||||
}
|
||||
template <class T, class U> inline constexpr bool operator<(const U& lhs, const optional<T>& rhs) {
|
||||
return rhs.has_value() ? lhs < rhs.value() : false;
|
||||
}
|
||||
template <class T, class U> inline constexpr bool operator<=(const optional<T>& lhs, const U& rhs) {
|
||||
return lhs.has_value() ? lhs.value() <= lhs : true;
|
||||
}
|
||||
template <class T, class U> inline constexpr bool operator<=(const U& lhs, const optional<T>& rhs) {
|
||||
return rhs.has_value() ? lhs <= rhs.value() : false;
|
||||
}
|
||||
template <class T, class U> inline constexpr bool operator>(const optional<T>& lhs, const U& rhs) {
|
||||
return lhs.has_value() ? lhs.value() > lhs : false;
|
||||
}
|
||||
template <class T, class U> inline constexpr bool operator>(const U& lhs, const optional<T>& rhs) {
|
||||
return rhs.has_value() ? lhs > rhs.value() : true;
|
||||
}
|
||||
template <class T, class U> inline constexpr bool operator>=(const optional<T>& lhs, const U& rhs) {
|
||||
return lhs.has_value() ? lhs.value() >= lhs : false;
|
||||
}
|
||||
template <class T, class U> inline constexpr bool operator>=(const U& lhs, const optional<T>& rhs) {
|
||||
return rhs.has_value() ? lhs >= rhs.value() : true;
|
||||
}
|
||||
|
||||
|
||||
// [optional.specalg], specialized algorithms
|
||||
template <class T, tl::enable_if_t<std::is_move_constructible<T>::value* = nullptr,
|
||||
tl:enable_if_t<std::is_swappable_v<T>>* = nullptr>
|
||||
void swap(optional<T>& lhs, optional<T>& rhs) noexcept(noexcept(lhs.swap(rhs))) {
|
||||
return lhs.swap(rhs);
|
||||
}
|
||||
|
||||
template <class T>
|
||||
inline constexpr optional<tl::decay_t<T>> make_optional(T&& v) {
|
||||
return optional<decay_t<T>>(std::forward<T>(v));
|
||||
}
|
||||
template <class T, class... Args>
|
||||
inline constexpr optional<T> make_optional(Args&&... args) {
|
||||
return optional<T>(in_place, std::forward<Args>(args)...);
|
||||
}
|
||||
template <class T, class U, class... Args>
|
||||
inline constexpr optional<T> make_optional(initializer_list<U> il, Args&&... args) {
|
||||
return optional<T>(in_place, il, std::forward<Args>(args)...);
|
||||
}
|
||||
}
|
||||
|
||||
// [optional.hash], hash support
|
||||
namespace std {
|
||||
template <class T> struct hash;
|
||||
template <class T, class = decltype(hash<tl::remove_const_t<T>>{})>
|
||||
struct hash<tl::optional<T>> {
|
||||
std::size_t operator() (const tl::optional<T>& o) {
|
||||
if (!o.has_value())
|
||||
return 0;
|
||||
|
||||
return hash<tl::remove_const_t<T>>()(o.value());
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
namespace tl {
|
||||
|
||||
template <class T>
|
||||
class optional {
|
||||
public:
|
||||
using value_type = T;
|
||||
|
||||
// [optional.ctor], constructors
|
||||
constexpr optional() noexcept : m_has_value(false) {
|
||||
new (&m_storage.d) dummy;
|
||||
}
|
||||
constexpr optional(nullopt_t) noexcept : optional() {}
|
||||
|
||||
constexpr optional(const optional& rhs);
|
||||
constexpr optional(optional&&) noexcept(see below);
|
||||
template <class... Args>
|
||||
constexpr explicit optional(in_place_t, Args&&...);
|
||||
template <class U, class... Args>
|
||||
constexpr explicit optional(in_place_t, initializer_list<U>, Args&&...);
|
||||
template <class U = T>
|
||||
EXPLICIT constexpr optional(U&&);
|
||||
template <class U>
|
||||
EXPLICIT optional(const optional<U>&);
|
||||
template <class U>
|
||||
EXPLICIT optional(optional<U>&&);
|
||||
|
||||
// [optional.dtor], destructor
|
||||
~optional();
|
||||
|
||||
// [optional.assign], assignment
|
||||
optional& operator=(nullopt_t) noexcept;
|
||||
optional& operator=(const optional&);
|
||||
optional& operator=(optional&&) noexcept(see below);
|
||||
template <class U = T> optional& operator=(U&&);
|
||||
template <class U> optional& operator=(const optional<U>&);
|
||||
template <class U> optional& operator=(optional<U>&&);
|
||||
template <class... Args> T& emplace(Args&&...);
|
||||
template <class U, class... Args> T& emplace(initializer_list<U>, Args&&...);
|
||||
|
||||
// [optional.swap], swap
|
||||
void swap(optional&) noexcept(see below);
|
||||
|
||||
// [optional.observe], observers
|
||||
constexpr const T* operator->() const {
|
||||
return std::addressof(m_storage.t);
|
||||
}
|
||||
constexpr T* operator->() {
|
||||
return std::addressof(m_storage.t);
|
||||
}
|
||||
constexpr const T& operator*() const& {
|
||||
return m_storage.t;
|
||||
}
|
||||
constexpr T& operator*() & {
|
||||
return m_storage.t;
|
||||
}
|
||||
constexpr T&& operator*() && {
|
||||
return std::move(m_storage.t);
|
||||
}
|
||||
constexpr const T&& operator*() const&& {
|
||||
return std::move(m_storage.t);
|
||||
}
|
||||
constexpr explicit operator bool() const noexcept {
|
||||
return m_has_value;
|
||||
}
|
||||
constexpr bool has_value() const noexcept {
|
||||
return m_has_value;
|
||||
}
|
||||
constexpr const T& value() const& {
|
||||
return has_value() ? m_storage.t : throw bad_optional_access();
|
||||
}
|
||||
constexpr T& value() & {
|
||||
return has_value() ? m_storage.t : throw bad_optional_access();
|
||||
}
|
||||
constexpr T&& value() && {
|
||||
return has_value() ? std::move(m_storage.t) : throw bad_optional_access();
|
||||
}
|
||||
constexpr const T&& value() const&& {
|
||||
return has_value() ? std::move(m_storage.t) : throw bad_optional_access();
|
||||
}
|
||||
template <class U> constexpr T value_or(U&&) const& {
|
||||
static_assert(std::is_copy_constructible<T>::value && std::is_convertible<U&&, T>::value,
|
||||
"T must be copy constructible and convertible from U");
|
||||
return has_value() ? value() : static_cast<T>(std::forward<U>(v));
|
||||
}
|
||||
template <class U> constexpr T value_or(U&&) && {
|
||||
static_assert(std::is_move_constructible<T>::value && std::is_convertible<U&&, T>::value,
|
||||
"T must be move constructible and convertible from U");
|
||||
return has_value() ? value() : static_cast<T>(std::forward<U>(v));
|
||||
}
|
||||
|
||||
// [optional.mod], modifiers
|
||||
void reset() noexcept;
|
||||
|
||||
private:
|
||||
struct dummy{};
|
||||
union {
|
||||
dummy d;
|
||||
T t;
|
||||
} m_storage;
|
||||
|
||||
bool m_has_value;
|
||||
};
|
||||
}
|
||||
Reference in New Issue
Block a user