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This commit is contained in:
Simon Brand
2017-10-26 21:51:24 +01:00
parent 3974935bdb
commit 013567d050
1 changed files with 336 additions and 222 deletions
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558
expected.hpp
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@@ -15,6 +15,8 @@
#define TL_EXPECTED_HPP
#include <type_traits>
#include <utility>
#include <exception>
namespace tl {
namespace detail {
@@ -22,15 +24,25 @@ template <bool E, class T = void>
using enable_if_t = typename std::enable_if<E, T>::type;
}
#ifndef TL_IN_PLACE_T_DEFINED
#define TL_IN_PLACE_T_DEFINED
/// \brief A tag type to tell optional to construct its value in-place
struct in_place_t {
explicit in_place_t() = default;
};
/// \brief A tag to tell optional to construct its value in-place
static constexpr in_place_t in_place{};
#endif
template <class E>
class unexpected {
public:
static_assert(!std::is_same<E, void>, "E must not be void");
static_assert(!std::is_same<E, void>::value, "E must not be void");
unexpected() = delete;
constexpr explicit unexpected(const E& e)
: m_val(e) {}
constexpr explicit unexpected(E&&)
constexpr explicit unexpected(E&& e)
: m_val(std::move(e)) {}
constexpr const E& value() const & { return m_val; }
@@ -51,11 +63,34 @@ using enable_if_t = typename std::enable_if<E, T>::type;
operator!=(const unexpected<E>& lhs, const unexpected<E>& rhs) {
return lhs.value() != rhs.value();
}
}
struct unexpect_t {
unexpect_t() = default;
};
static constexpr unexpect_t unexpect{};
namespace detail {
template <class T, class E, bool = std::is_trivially_destrictible<T>::value, bool = std::is_trivially_destrictible<E>::value>
template <class T, class E, bool = std::is_trivially_destructible<T>::value, bool = std::is_trivially_destructible<E>::value>
struct expected_storage_base {
constexpr expected_storage_base()
: m_val(T{}), m_has_val(true) {}
template <class... Args, detail::enable_if_t<std::is_constructible<T, Args&&...>::value>* = nullptr>
constexpr expected_storage_base(in_place_t, Args&&... args) :
m_val(std::forward<Args>(args)...), m_has_val(true) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<T, std::initializer_list<U>&, Args&&...>::value>* = nullptr>
constexpr expected_storage_base (in_place_t, std::initializer_list<U> il, Args&&... args) :
m_val(il, std::forward<Args>(args)...), m_has_val(true) {}
template <class... Args, detail::enable_if_t<std::is_constructible<E, Args&&...>::value>* = nullptr>
constexpr explicit expected_storage_base(unexpect_t, Args&&... args) :
m_unexpect(std::forward<Args>(args)...), m_has_val(false) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<E, std::initializer_list<U>&, Args&&...>::value>* = 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();
@@ -73,6 +108,26 @@ namespace detail {
template <class T, class E>
struct expected_storage_base<T,E,true,true> {
constexpr expected_storage_base()
: m_val(T{}), m_has_val(true) {}
template <class... Args, detail::enable_if_t<std::is_constructible<T, Args&&...>::value>* = nullptr>
constexpr expected_storage_base(in_place_t, Args&&... args) :
m_val(std::forward<Args>(args)...), m_has_val(true) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<T, std::initializer_list<U>&, Args&&...>::value>* = nullptr>
constexpr expected_storage_base (in_place_t, std::initializer_list<U> il, Args&&... args) :
m_val(il, std::forward<Args>(args)...), m_has_val(true) {}
template <class... Args, detail::enable_if_t<std::is_constructible<E, Args&&...>::value>* = nullptr>
constexpr explicit expected_storage_base(unexpect_t, Args&&... args) :
m_unexpect(std::forward<Args>(args)...), m_has_val(false) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<E, std::initializer_list<U>&, Args&&...>::value>* = 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;
bool m_has_val;
union {
@@ -83,6 +138,26 @@ namespace detail {
template <class T, class E>
struct expected_storage_base<T,E,true,false> {
constexpr expected_storage_base()
: m_val(T{}), m_has_val(true) {}
template <class... Args, detail::enable_if_t<std::is_constructible<T, Args&&...>::value>* = nullptr>
constexpr expected_storage_base(in_place_t, Args&&... args) :
m_val(std::forward<Args>(args)...), m_has_val(true) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<T, std::initializer_list<U>&, Args&&...>::value>* = nullptr>
constexpr expected_storage_base (in_place_t, std::initializer_list<U> il, Args&&... args) :
m_val(il, std::forward<Args>(args)...), m_has_val(true) {}
template <class... Args, detail::enable_if_t<std::is_constructible<E, Args&&...>::value>* = nullptr>
constexpr explicit expected_storage_base(unexpect_t, Args&&... args) :
m_unexpect(std::forward<Args>(args)...), m_has_val(false) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<E, std::initializer_list<U>&, Args&&...>::value>* = 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_unexpect.~unexpected<E>();
@@ -99,6 +174,26 @@ namespace detail {
template <class T, class E>
struct expected_storage_base<T,E,false,true> {
constexpr expected_storage_base()
: m_val(T{}), m_has_val(true) {}
template <class... Args, detail::enable_if_t<std::is_constructible<T, Args&&...>::value>* = nullptr>
constexpr expected_storage_base(in_place_t, Args&&... args) :
m_val(std::forward<Args>(args)...), m_has_val(true) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<T, std::initializer_list<U>&, Args&&...>::value>* = nullptr>
constexpr expected_storage_base(in_place_t, std::initializer_list<U> il, Args&&... args) :
m_val(il, std::forward<Args>(args)...), m_has_val(true) {}
template <class... Args, detail::enable_if_t<std::is_constructible<E, Args&&...>::value>* = nullptr>
constexpr explicit expected_storage_base(unexpect_t, Args&&... args) :
m_unexpect(std::forward<Args>(args)...), m_has_val(false) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<E, std::initializer_list<U>&, Args&&...>::value>* = 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();
@@ -107,24 +202,49 @@ namespace detail {
bool m_has_val;
union {
T m_val;
unexpected<U> m_unexpect;
unexpected<E> m_unexpect;
};
};
template <class T, class E>
template <class E>
struct expected_storage_base<void,E,false,true> {
constexpr expected_storage_base()
: m_val(), m_has_val(true) {}
template <class... Args, detail::enable_if_t<std::is_constructible<E, Args&&...>::value>* = nullptr>
constexpr explicit expected_storage_base(unexpect_t, Args&&... args) :
m_unexpect(std::forward<Args>(args)...), m_has_val(false) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<E, std::initializer_list<U>&, Args&&...>::value>* = 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;
bool m_has_val;
struct dummy{};
union {
dummy m_val;
unexpected<U> m_unexpect;
unexpected<E> m_unexpect;
};
};
template <class T, class E>
template <class E>
struct expected_storage_base<void,E,false,false> {
constexpr expected_storage_base()
: m_val(), m_has_val(true) {}
template <class... Args, detail::enable_if_t<std::is_constructible<E, Args&&...>::value>* = nullptr>
constexpr explicit expected_storage_base(unexpect_t, Args&&... args) :
m_unexpect(std::forward<Args>(args)...), m_has_val(false) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<E, std::initializer_list<U>&, Args&&...>::value>* = 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();
@@ -135,7 +255,7 @@ namespace detail {
struct dummy{};
union {
dummy m_val;
unexpected<U> m_unexpect;
unexpected<E> m_unexpect;
};
};
@@ -144,216 +264,9 @@ namespace detail {
class expected_ctor_base{};
}
template <class T, class E>
class expected : private expected_storage_base<T,E>, private expected_ctor_base<T,E> {
static_assert(!std::is_reference<T>::value, "T must not be a reference");
static_assert(!std::is_same<T, std::remove_cv<in_place_t>>::value, "T must not be in_place_t");
static_assert(!std::is_same<T, std::remove_cv<unexpect_t>>::value, "T must not be unexpect_t");
static_assert(!std::is_same<T, std::remove_cv<unexpected<E>>::value, "T must not be unexpected<E>");
static_assert(!std::is_reference<E>::value, "E must not be a reference");
static_assert(!std::is_same<T, void>::value, "T must not be void");
public:
typedef T value_type;
typedef E error_type;
typedef unexpected<E> unexpected_type;
template <class U>
struct rebind {
using type = expected<U, error_type>;
};
// X.Z.4.1, constructors
constexpr expected_storage_base() :
m_val(T{}), m_has_val(true) {}
template <class... Args, detail::enable_if_t<std::is_constructible<T, Args&&...>::value>* = nullptr>
constexpr expected_storage_base(in_place_t, Args&&... args) :
m_val(std::forward<Args>(args)...), m_has_val(true) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<T, std::initializer_list<U>&, Args&&...>::value>
constexpr expected_storage_base(in_place_t, std::initializer_list<U> il, Args&&... args) :
m_val(il, std::forward<Args>(args)...), m_has_val(true) {}
template <class G = E, detail::enable_if_t<std::is_constructible<E, const G&>::value>* = nullptr, detail::enable_if_t<!std::is_convertible<const G&, E>::value>* = nullptr>
explicit constexpr expected(unexpected<G> const& e)
: m_unexpect(std::move(e)), m_has_value(false) {}
template <class G = E, detail::enable_if_t<std::is_constructible<E, const G&>::value>* = nullptr, detail::enable_if_t<std::is_convertible<const G&, E>::value>* = nullptr>
constexpr expected(unexpected<G> const& e)
: m_unexpect(std::move(e)), m_has_value(false) {}
template <class G = E, detail::enable_if_t<std::is_constructible<E, G&&>::value>* = nullptr, detail::enable_if_t<!std::is_convertible<G&&, E>::value>* = nullptr>
explicit constexpr expected(unexpected<G> && e) noexcept(std::is_nothrow_constructible<E, G&&>::value)
: m_unexpect(std::move(e)), m_has_value(false) {}
template <class G = E, detail::enable_if_t<std::is_constructible<E, G&&>::value>* = nullptr, detail::enable_if_t<std::is_convertible<G&&, E>::value>* = nullptr>
constexpr expected(unexpected<G> && e) noexcept(std::is_nothrow_constructible<E, G&&>::value)
: m_unexpect(std::move(e)), m_has_value(false) {}
template <class... Args, detail::enable_if_t<std::is_constructible<E, Args&&...>::value>* = nullptr>
constexpr explicit expected(unexpect_t, Args&&... args) :
m_unexpect(std::forward<Args>(args)...), m_has_val(false) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<E, std::initializer_list<U>&, Args&&...>::value>* = nullptr>
constexpr explicit expected(unexpect_t, std::initializer_list<U> il, Args&&... args) :
m_unexpect(il, std::forward<Args>(args)...), m_has_val(false) {}
constexpr expected(const expected& rhs) {
if (rhs.has_value()) {
new (std::addressof(m_value)) (*rhs);
}
else {
new (std::addressof(m_unexpect)) (unexpected(rhs.error()));
}
}
//TODO SFINAE
constexpr expected(expected&&) noexcept(std::is_nothrow_move_constructible_v<T> && std::is_nothrow_move_constructible_v<E>) {
if (rhs.has_value()) {
new (std::addressof(m_value)) (std::move(*rhs));
}
else {
new (std::addressof(m_unexpect)) (unexpected(std::move(rhs.error())));
}
}
//TODO SFINAE
template <class U, class G, detail::enable_if_t<!std::is_convertible<U const&, T> || !std::is_convertible<G const&, E>::value>* = nullptr>
explicit constexpr expected(const expected<U, G>& rhs) {
if (rhs.has_value()) {
new (std::addressof(m_value)) (*rhs);
}
else {
new (std::addressof(m_unexpect)) (unexpected(rhs.error()));
}
}
//TODO SFINAE
template <class U, class G, detail::enable_if_t<!std::is_convertible<U&&, T> || !std::is_convertible<G&&, E>::value>* = nullptr>
explicit constexpr expected(const expected<U, G>& rhs) {
if (rhs.has_value()) {
new (std::addressof(m_value)) (*rhs);
}
else {
new (std::addressof(m_unexpect)) (unexpected(rhs.error()));
}
}
//TODO SFINAE
template <class U, class G, detail::enable_if_t<std::is_convertible<U&&, T> || std::is_convertible<G&&, E>::value>* = nullptr>
constexpr expected(expected<U, G>&&) {
if (rhs.has_value()) {
new (std::addressof(m_value)) (std::move(*rhs));
}
else {
new (std::addressof(m_unexpect)) (unexpected(std::move(rhs.error())));
}
}
//TODO SFINAE
template <class U = T, detail::enable_if_t<!std::is_convertible<U&&, T>::value>* = nullptr>
explicit constexpr expected(U&& v)
: expected_storage_base(in_place, std::forward<U>(v))
{}
//TODO SFINAE
template <class U = T, detail::enable_if_t<std::is_convertible<U&&, T>::value>* = nullptr>
constexpr expected(U&& v)
: expected_storage_base(in_place, std::forward<U>(v))
{}
//TODO
expected& operator=(const expected&);
expected& operator=(expected&&) noexcept(see below);
template <class U = T> expected& operator=(U&&);
template <class G = E>
expected& operator=(const unexpected<G>&);
template <class G = E>
expected& operator=(unexpected<G>&&) noexcept(see below);
template <class... Args>
void emplace(Args&&...);
template <class U, class... Args>
void emplace(initializer_list<U>, Args&&...);
//TODO SFINAE
void swap(expected& rhs) noexcept(std::is_nothrow_move_constructible<T>::value && noexcept(swap(declval<T&>(), declval<T&>())) && std::is_nothrow_move_constructible<E>::value && noexcept(swap(declval<E&>(), declval<E&>())))
{
if (has_value() && rhs.has_value()) {
using std::swap;
swap(m_val, rhs.m_val);
}
else if (!has_value() && rhs.has_value()) {
using std::swap;
swap(m_unexpect, rhs.m_unexpect);
}
else if (has_value()) {
auto temp = std::move(rhs.m_unexpect);
new (std::addressof(rhs.m_val)) (m_val);
new (std::addressof(m_unexpect)) (temp);
std::swap(m_has_value, rhs.m_has_value);
}
else {
auto temp = std::move(m_unexpect);
new (std::addressof(m_val)) (rhs.m_val);
new (std::addressof(rhs.m_unexpect)) (temp);
std::swap(m_has_value, rhs.m_has_value);
}
}
constexpr const T* operator ->() const { return std::addressof(m_val); }
constexpr T* operator ->() { return std::addressof(m_val); }
constexpr const T& operator *() const& { return m_val; }
constexpr T& operator *() & { return m_val; }
constexpr const T&& operator *() const && { return std::move(m_val); }
constexpr T&& operator *() && { return std::move(m_val); }
constexpr explicit operator bool() const noexcept { return m_has_val; }
constexpr bool has_value() const noexcept { return m_has_val; }
constexpr const T& value() const& {
if (!m_has_value) throw bad_expected_access();
return m_value;
}
constexpr T& value() & {
if (!m_has_value) throw bad_expected_access();
return m_value;
}
constexpr const T&& value() const && {
if (!m_has_value) throw bad_expected_access();
return std::move(m_value);
}
constexpr T&& value() && {
if (!m_has_value) throw bad_expected_access();
return std::move(m_value);
}
constexpr const E& error() const& { return m_unexpect.value(); }
constexpr E& error() & { return m_unexpect.value(); }
constexpr const E&& error() const && { return std:move(m_unexpect.value()); }
constexpr E&& error() && { return std:move(m_unexpect.value()); }
template <class U>
constexpr T value_or(U&& v) const& {
static_assert(std::is_copy_constructible<T>::value && std::is_convertible<U&&, T>::value, "T must be copy-constructible and convertible to from U&&");
return bool(*this) ? **this : static_cast<T>(std::forward<U>(v));
}
template <class U>
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 to from U&&");
return bool(*this) ? std::move(**this) : static_cast<T>(std::forward<U>(v));
}
};
//TODO
template <class E>
class expected<void, E> {
};
struct unexpect_t {
unexpect_t() = default;
};
inline constexpr unexpect_t unexpect{};
template <class E>
class bad_expected_access : public bad_expected_access<void> {
class bad_expected_access : public std::exception {
public:
explicit bad_expected_access(E e)
: m_val(std::move(e)) {}
@@ -370,14 +283,214 @@ private:
E m_val;
};
template <>
class bad_expected_access<void> : public exception {
template <class T, class E>
class expected : private detail::expected_storage_base<T,E>, private detail::expected_ctor_base<T,E> {
static_assert(!std::is_reference<T>::value, "T must not be a reference");
static_assert(!std::is_same<T, std::remove_cv<in_place_t>>::value, "T must not be in_place_t");
static_assert(!std::is_same<T, std::remove_cv<unexpect_t>>::value, "T must not be unexpect_t");
static_assert(!std::is_same<T, std::remove_cv<unexpected<E>>>::value, "T must not be unexpected<E>");
static_assert(!std::is_reference<E>::value, "E must not be a reference");
static_assert(!std::is_same<T, void>::value, "T must not be void");
T* valptr() { return std::addressof(this->m_value); }
unexpected<E>* errptr() { return std::addressof(this->m_unexpect); }
T& val() { return this->m_value; }
unexpected<E>& err() { return this->m_unexpect; }
const T& val() const { return this->m_value; }
const unexpected<E>& err() const { return this->m_unexpect; }
using storage_base = detail::expected_storage_base<T,E>;
public:
explicit bad_expected_access();
typedef T value_type;
typedef E error_type;
typedef unexpected<E> unexpected_type;
constexpr expected() = default;
template <class... Args, detail::enable_if_t<std::is_constructible<T, Args&&...>::value>* = nullptr>
constexpr expected(in_place_t, Args&&... args) :
storage_base(in_place, std::forward<Args>(args)...){}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<T, std::initializer_list<U>&, Args&&...>::value>* = nullptr>
constexpr expected(in_place_t, std::initializer_list<U> il, Args&&... args) :
storage_base(in_place, il, std::forward<Args>(args)...){}
template <class G = E, detail::enable_if_t<std::is_constructible<E, const G&>::value>* = nullptr, detail::enable_if_t<!std::is_convertible<const G&, E>::value>* = nullptr>
explicit constexpr expected(unexpected<G> const& e)
: storage_base(unexpect, e) {}
template <class G = E, detail::enable_if_t<std::is_constructible<E, const G&>::value>* = nullptr, detail::enable_if_t<std::is_convertible<const G&, E>::value>* = nullptr>
constexpr expected(unexpected<G> const& e)
: storage_base(unexpect, e) {}
template <class G = E, detail::enable_if_t<std::is_constructible<E, G&&>::value>* = nullptr, detail::enable_if_t<!std::is_convertible<G&&, E>::value>* = nullptr>
explicit constexpr expected(unexpected<G> && e) noexcept(std::is_nothrow_constructible<E, G&&>::value)
: storage_base(unexpect, std::move(e)) {}
template <class G = E, detail::enable_if_t<std::is_constructible<E, G&&>::value>* = nullptr, detail::enable_if_t<std::is_convertible<G&&, E>::value>* = nullptr>
constexpr expected(unexpected<G> && e) noexcept(std::is_nothrow_constructible<E, G&&>::value)
: storage_base(unexpect, std::move(e)) {}
template <class... Args, detail::enable_if_t<std::is_constructible<E, Args&&...>::value>* = nullptr>
constexpr explicit expected(unexpect_t, Args&&... args)
: storage_base(unexpect, std::forward<Args>(args)...) {}
template <class U, class... Args, detail::enable_if_t<std::is_constructible<E, std::initializer_list<U>&, Args&&...>::value>* = nullptr>
constexpr explicit expected(unexpect_t, std::initializer_list<U> il, Args&&... args)
: storage_base(unexpect, il, std::forward<Args>(args)...) {}
constexpr expected(const expected& rhs) {
if (rhs.has_value()) {
::new (valptr()) T (*rhs);
}
else {
::new (errptr()) unexpected_type (unexpected<E>(rhs.error()));
}
}
//TODO SFINAE
constexpr expected(expected&& rhs) noexcept(std::is_nothrow_move_constructible<T>::value && std::is_nothrow_move_constructible<E>::value) {
if (rhs.has_value()) {
::new (valptr()) T (std::move(*rhs));
}
else {
::new (errptr()) unexpected_type (unexpected<E>(std::move(rhs.error())));
}
}
//TODO SFINAE
template <class U, class G, detail::enable_if_t<(!std::is_convertible<U const&, T>::value || !std::is_convertible<G const&, E>::value)>* = nullptr>
explicit constexpr expected(const expected<U, G>& rhs) {
if (rhs.has_value()) {
::new (valptr()) T (*rhs);
}
else {
::new (errptr()) unexpected_type (unexpected<E>(rhs.error()));
}
}
//TODO SFINAE
template <class U, class G, detail::enable_if_t<(!std::is_convertible<U&&, T>::value || !std::is_convertible<G&&, E>::value)>* = nullptr>
explicit constexpr expected(const expected<U, G>& rhs) {
if (rhs.has_value()) {
::new (valptr()) T (*rhs);
}
else {
::new (errptr()) unexpected_type (unexpected<E>(rhs.error()));
}
}
//TODO SFINAE
template <class U, class G, detail::enable_if_t<(std::is_convertible<U&&, T>::value || std::is_convertible<G&&, E>::value)>* = nullptr>
constexpr expected(expected<U, G>&& rhs) {
if (rhs.has_value()) {
::new (valptr()) T (std::move(*rhs));
}
else {
::new (errptr()) unexpected_type (unexpected<E>(std::move(rhs.error())));
}
}
//TODO SFINAE
template <class U = T, detail::enable_if_t<!std::is_convertible<U&&, T>::value>* = nullptr>
explicit constexpr expected(U&& v)
: expected(in_place, std::forward<U>(v))
{}
//TODO SFINAE
template <class U = T, detail::enable_if_t<std::is_convertible<U&&, T>::value>* = nullptr>
constexpr expected(U&& v)
: expected(in_place, std::forward<U>(v))
{}
//TODO
expected& operator=(const expected&);
expected& operator=(expected&&) noexcept;
template <class U = T> expected& operator=(U&&);
template <class G = E>
expected& operator=(const unexpected<G>&);
template <class G = E>
expected& operator=(unexpected<G>&&) noexcept;
template <class... Args>
void emplace(Args&&...);
template <class U, class... Args>
void emplace(std::initializer_list<U>, Args&&...);
//TODO SFINAE
void swap(expected& rhs) noexcept(std::is_nothrow_move_constructible<T>::value && noexcept(swap(std::declval<T&>(), std::declval<T&>())) && std::is_nothrow_move_constructible<E>::value && noexcept(swap(std::declval<E&>(), std::declval<E&>())))
{
if (has_value() && rhs.has_value()) {
using std::swap;
swap(val(), rhs.val());
}
else if (!has_value() && rhs.has_value()) {
using std::swap;
swap(err(), rhs.err());
}
else if (has_value()) {
auto temp = std::move(rhs.err());
::new (rhs.valptr()) T (val());
::new (errptr()) unexpected_type (std::move(temp));
std::swap(this->m_has_val, rhs.m_has_val);
}
else {
auto temp = std::move(this->err());
::new (valptr()) T (rhs.val());
::new (errptr()) unexpected_type (std::move(temp));
std::swap(this->m_has_val, rhs.m_has_val);
}
}
constexpr const T* operator ->() const { return valptr(); }
constexpr T* operator ->() { return valptr(); }
constexpr const T& operator *() const& { return val(); }
constexpr T& operator *() & { return val(); }
constexpr const T&& operator *() const && { return std::move(val()); }
constexpr T&& operator *() && { return std::move(val()); }
constexpr explicit operator bool() const noexcept { return this->m_has_val; }
constexpr bool has_value() const noexcept { return this->m_has_val; }
constexpr const T& value() const& {
if (!has_value()) throw bad_expected_access<E>(err());
return val();
}
constexpr T& value() & {
if (!has_value()) throw bad_expected_access<E>(err());
return val();
}
constexpr const T&& value() const && {
if (!has_value()) throw bad_expected_access<E>(err());
return std::move(val());
}
constexpr T&& value() && {
if (!has_value()) throw bad_expected_access<E>(err());
return std::move(val());
}
constexpr const E& error() const& { return err().value(); }
constexpr E& error() & { return err().value(); }
constexpr const E&& error() const && { return std::move(err().value()); }
constexpr E&& error() && { return std::move(err().value()); }
template <class U>
constexpr T value_or(U&& v) const& {
static_assert(std::is_copy_constructible<T>::value && std::is_convertible<U&&, T>::value, "T must be copy-constructible and convertible to from U&&");
return bool(*this) ? **this : static_cast<T>(std::forward<U>(v));
}
template <class U>
T value_or(U&& v) && {
static_assert(std::is_move_constructible<T>::value && std::is_convertible<U&&, T>::value, "T must be move-constructible and convertible to from U&&");
return bool(*this) ? std::move(**this) : static_cast<T>(std::forward<U>(v));
}
};
template <>
class bad_expected_access<void>;
//TODO
template <class E>
class expected<void, E> {
};
template <class T, class E>
constexpr bool operator==(const expected<T, E>& lhs, const expected<T, E>& rhs) {
@@ -432,5 +545,6 @@ template <class T, class E, detail::enable_if_t<std::is_move_constructible<T>::v
void swap(expected<T, E>& lhs, expected<T, E>& rhs) noexcept(noexcept(lhs.swap(rhs))) {
lhs.swap(rhs);
}
}
#endif