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///
// expected - An implementation of std::expected with extensions
// Written in 2017 by Simon Brand (@TartanLlama)
//
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to the
// public domain worldwide. This software is distributed without any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication
// along with this software. If not, see
// <http://creativecommons.org/publicdomain/zero/1.0/>.
///
#ifndef TL_EXPECTED_HPP
#define TL_EXPECTED_HPP
#define TL_EXPECTED_VERSION_MAJOR 0
#define TL_EXPECTED_VERSION_MINOR 2
#include <exception>
#include <functional>
#include <type_traits>
#include <utility>
#if defined(__EXCEPTIONS) || defined(_CPPUNWIND)
#define TL_EXPECTED_EXCEPTIONS_ENABLED
#endif
#if (defined(_MSC_VER) && _MSC_VER == 1900)
/// \exclude
#define TL_EXPECTED_MSVC2015
#define TL_EXPECTED_MSVC2015_CONSTEXPR
#else
#define TL_EXPECTED_MSVC2015_CONSTEXPR constexpr
#endif
#if (defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 && \
!defined(__clang__))
/// \exclude
#define TL_EXPECTED_GCC49
#endif
#if (defined(__GNUC__) && __GNUC__ == 5 && __GNUC_MINOR__ <= 4 && \
!defined(__clang__))
/// \exclude
#define TL_EXPECTED_GCC54
#endif
#if (defined(__GNUC__) && __GNUC__ == 5 && __GNUC_MINOR__ <= 5 && \
!defined(__clang__))
/// \exclude
#define TL_EXPECTED_GCC55
#endif
#if (defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 && \
!defined(__clang__))
// GCC < 5 doesn't support overloading on const&& for member functions
/// \exclude
#define TL_EXPECTED_NO_CONSTRR
// GCC < 5 doesn't support some standard C++11 type traits
/// \exclude
#define TL_EXPECTED_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
std::has_trivial_copy_constructor<T>
/// \exclude
#define TL_EXPECTED_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
std::has_trivial_copy_assign<T>
// This one will be different for GCC 5.7 if it's ever supported
/// \exclude
#define TL_EXPECTED_IS_TRIVIALLY_DESTRUCTIBLE(T) \
std::is_trivially_destructible<T>
// GCC 5 < v < 8 has a bug in is_trivially_copy_constructible which breaks std::vector
// for non-copyable types
#elif (defined(__GNUC__) && __GNUC__ < 8 && \
!defined(__clang__))
#ifndef TL_GCC_LESS_8_TRIVIALLY_COPY_CONSTRUCTIBLE_MUTEX
#define TL_GCC_LESS_8_TRIVIALLY_COPY_CONSTRUCTIBLE_MUTEX
namespace tl {
namespace detail {
template<class T>
struct is_trivially_copy_constructible : std::is_trivially_copy_constructible<T>{};
#ifdef _GLIBCXX_VECTOR
template<class T, class A>
struct is_trivially_copy_constructible<std::vector<T,A>>
: std::is_trivially_copy_constructible<T>{};
#endif
}
}
#endif
#define TL_EXPECTED_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
tl::detail::is_trivially_copy_constructible<T>
#define TL_EXPECTED_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
std::is_trivially_copy_assignable<T>
#define TL_EXPECTED_IS_TRIVIALLY_DESTRUCTIBLE(T) std::is_trivially_destructible<T>
#else
/// \exclude
#define TL_EXPECTED_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
std::is_trivially_copy_constructible<T>
/// \exclude
#define TL_EXPECTED_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
std::is_trivially_copy_assignable<T>
/// \exclude
#define TL_EXPECTED_IS_TRIVIALLY_DESTRUCTIBLE(T) \
std::is_trivially_destructible<T>
#endif
#if __cplusplus > 201103L
/// \exclude
#define TL_EXPECTED_CXX14
#endif
#ifdef TL_EXPECTED_GCC49
#define TL_EXPECTED_GCC49_CONSTEXPR
#else
#define TL_EXPECTED_GCC49_CONSTEXPR constexpr
#endif
#if (__cplusplus == 201103L || defined(TL_EXPECTED_MSVC2015) || \
defined(TL_EXPECTED_GCC49))
/// \exclude
#define TL_EXPECTED_11_CONSTEXPR
#else
/// \exclude
#define TL_EXPECTED_11_CONSTEXPR constexpr
#endif
namespace tl {
template <class T, class E> class expected;
#ifndef TL_MONOSTATE_INPLACE_MUTEX
#define TL_MONOSTATE_INPLACE_MUTEX
/// \brief Used to represent an expected with no data
class monostate {};
/// \brief A tag type to tell expected to construct its value in-place
struct in_place_t {
explicit in_place_t() = default;
};
/// \brief A tag to tell expected to construct its value in-place
static constexpr in_place_t in_place{};
#endif
/// Used as a wrapper to store the unexpected value
template <class E> class unexpected {
public:
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 &&e) : m_val(std::move(e)) {}
/// \returns the contained value
/// \group unexpected_value
constexpr const E &value() const & { return m_val; }
/// \group unexpected_value
TL_EXPECTED_11_CONSTEXPR E &value() & { return m_val; }
/// \group unexpected_value
TL_EXPECTED_11_CONSTEXPR E &&value() && { return std::move(m_val); }
/// \exclude
constexpr const E &&value() const && { return std::move(m_val); }
private:
E m_val;
};
/// \brief Compares two unexpected objects
/// \details Simply compares lhs.value() to rhs.value()
/// \group unexpected_relop
template <class E>
constexpr bool operator==(const unexpected<E> &lhs, const unexpected<E> &rhs) {
return lhs.value() == rhs.value();
}
/// \group unexpected_relop
template <class E>
constexpr bool operator!=(const unexpected<E> &lhs, const unexpected<E> &rhs) {
return lhs.value() != rhs.value();
}
/// \group unexpected_relop
template <class E>
constexpr bool operator<(const unexpected<E> &lhs, const unexpected<E> &rhs) {
return lhs.value() < rhs.value();
}
/// \group unexpected_relop
template <class E>
constexpr bool operator<=(const unexpected<E> &lhs, const unexpected<E> &rhs) {
return lhs.value() <= rhs.value();
}
/// \group unexpected_relop
template <class E>
constexpr bool operator>(const unexpected<E> &lhs, const unexpected<E> &rhs) {
return lhs.value() > rhs.value();
}
/// \group unexpected_relop
template <class E>
constexpr bool operator>=(const unexpected<E> &lhs, const unexpected<E> &rhs) {
return lhs.value() >= rhs.value();
}
/// Create an `unexpected` from `e`, deducing the return type
///
/// *Example:*
/// auto e1 = tl::make_unexpected(42);
/// unexpected<int> e2 (42); //same semantics
template <class E>
unexpected<typename std::decay<E>::type> make_unexpected(E &&e) {
return unexpected<typename std::decay<E>::type>(std::forward<E>(e));
}
/// \brief A tag type to tell expected to construct the unexpected value
struct unexpect_t {
unexpect_t() = default;
};
/// \brief A tag to tell expected to construct the unexpected value
static constexpr unexpect_t unexpect{};
/// \exclude
namespace detail {
template<typename E>
[[noreturn]] TL_EXPECTED_11_CONSTEXPR void throw_exception(E &&e) {
#ifdef TL_EXPECTED_EXCEPTIONS_ENABLED
throw std::forward<E>(e);
#else
#ifdef _MSC_VER
__assume(0);
#else
__builtin_unreachable();
#endif
#endif
}
#ifndef TL_TRAITS_MUTEX
#define TL_TRAITS_MUTEX
// C++14-style aliases for brevity
template <class T> using remove_const_t = typename std::remove_const<T>::type;
template <class T>
using remove_reference_t = typename std::remove_reference<T>::type;
template <class T> using decay_t = typename std::decay<T>::type;
template <bool E, class T = void>
using enable_if_t = typename std::enable_if<E, T>::type;
template <bool B, class T, class F>
using conditional_t = typename std::conditional<B, T, F>::type;
// std::conjunction from C++17
template <class...> struct conjunction : std::true_type {};
template <class B> struct conjunction<B> : B {};
template <class B, class... Bs>
struct conjunction<B, Bs...>
: std::conditional<bool(B::value), conjunction<Bs...>, B>::type {};
// std::invoke from C++17
// https://stackoverflow.com/questions/38288042/c11-14-invoke-workaround
template <typename Fn, typename... Args,
typename = enable_if_t<std::is_member_pointer<decay_t<Fn>>{}>,
int = 0>
constexpr auto invoke(Fn &&f, Args &&... args) noexcept(
noexcept(std::mem_fn(f)(std::forward<Args>(args)...)))
-> decltype(std::mem_fn(f)(std::forward<Args>(args)...)) {
return std::mem_fn(f)(std::forward<Args>(args)...);
}
template <typename Fn, typename... Args,
typename = enable_if_t<!std::is_member_pointer<decay_t<Fn>>{}>>
constexpr auto invoke(Fn &&f, Args &&... args) noexcept(
noexcept(std::forward<Fn>(f)(std::forward<Args>(args)...)))
-> decltype(std::forward<Fn>(f)(std::forward<Args>(args)...)) {
return std::forward<Fn>(f)(std::forward<Args>(args)...);
}
// std::invoke_result from C++17
template <class F, class, class... Us> struct invoke_result_impl;
template <class F, class... Us>
struct invoke_result_impl<
F, decltype(detail::invoke(std::declval<F>(), std::declval<Us>()...), void()),
Us...> {
using type = decltype(detail::invoke(std::declval<F>(), std::declval<Us>()...));
};
template <class F, class... Us>
using invoke_result = invoke_result_impl<F, void, Us...>;
template <class F, class... Us>
using invoke_result_t = typename invoke_result<F, Us...>::type;
#endif
// Trait for checking if a type is a tl::expected
template <class T> struct is_expected_impl : std::false_type {};
template <class T, class E>
struct is_expected_impl<expected<T, E>> : std::true_type {};
template <class T> using is_expected = is_expected_impl<decay_t<T>>;
template <class T, class E, class U>
using expected_enable_forward_value = detail::enable_if_t<
std::is_constructible<T, U &&>::value &&
!std::is_same<detail::decay_t<U>, in_place_t>::value &&
!std::is_same<expected<T, E>, detail::decay_t<U>>::value &&
!std::is_same<unexpected<E>, detail::decay_t<U>>::value>;
template <class T, class E, class U, class G, class UR, class GR>
using expected_enable_from_other = detail::enable_if_t<
std::is_constructible<T, UR>::value &&
std::is_constructible<E, GR>::value &&
!std::is_constructible<T, expected<U, G> &>::value &&
!std::is_constructible<T, expected<U, G> &&>::value &&
!std::is_constructible<T, const expected<U, G> &>::value &&
!std::is_constructible<T, const expected<U, G> &&>::value &&
!std::is_convertible<expected<U, G> &, T>::value &&
!std::is_convertible<expected<U, G> &&, T>::value &&
!std::is_convertible<const expected<U, G> &, T>::value &&
!std::is_convertible<const expected<U, G> &&, T>::value>;
template <class T, class U>
using is_void_or = conditional_t<std::is_void<T>::value, std::true_type, U>;
template <class T>
using is_copy_constructible_or_void =
is_void_or<T, std::is_copy_constructible<T>>;
template <class T>
using is_move_constructible_or_void =
is_void_or<T, std::is_move_constructible<T>>;
template <class T>
using is_copy_assignable_or_void =
is_void_or<T, std::is_copy_assignable<T>>;
template <class T>
using is_move_assignable_or_void =
is_void_or<T, std::is_move_assignable<T>>;
} // namespace detail
/// \exclude
namespace detail {
struct no_init_t {};
static constexpr no_init_t no_init{};
// Implements the storage of the values, and ensures that the destructor is
// trivial if it can be.
//
// This specialization is for where neither `T` or `E` is trivially
// destructible, so the destructors must be called on destruction of the
// `expected`
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) {}
constexpr expected_storage_base(no_init_t) : m_no_init(), m_has_val(false) {}
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();
} else {
m_unexpect.~unexpected<E>();
}
}
union {
char m_no_init;
T m_val;
unexpected<E> m_unexpect;
};
bool m_has_val;
};
// This specialization is for when both `T` and `E` are trivially-destructible,
// so the destructor of the `expected` can be trivial.
template <class T, class E> struct expected_storage_base<T, E, true, true> {
constexpr expected_storage_base() : m_val(T{}), m_has_val(true) {}
constexpr expected_storage_base(no_init_t) : m_no_init(), m_has_val(false) {}
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;
union {
char m_no_init;
T m_val;
unexpected<E> m_unexpect;
};
bool m_has_val;
};
// T is trivial, E is not.
template <class T, class E> struct expected_storage_base<T, E, true, false> {
constexpr expected_storage_base() : m_val(T{}), m_has_val(true) {}
TL_EXPECTED_MSVC2015_CONSTEXPR expected_storage_base(no_init_t)
: m_no_init(), m_has_val(false) {}
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>();
}
}
union {
char m_no_init;
T m_val;
unexpected<E> m_unexpect;
};
bool m_has_val;
};
// E is trivial, T is not.
template <class T, class E> struct expected_storage_base<T, E, false, true> {
constexpr expected_storage_base() : m_val(T{}), m_has_val(true) {}
constexpr expected_storage_base(no_init_t) : m_no_init(), m_has_val(false) {}
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();
}
}
union {
char m_no_init;
T m_val;
unexpected<E> m_unexpect;
};
bool m_has_val;
};
// `T` is `void`, `E` is trivially-destructible
template <class E> struct expected_storage_base<void, E, false, true> {
TL_EXPECTED_MSVC2015_CONSTEXPR expected_storage_base() : m_has_val(true) {}
constexpr expected_storage_base(no_init_t) : m_val(), m_has_val(false) {}
constexpr expected_storage_base(in_place_t) : 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;
struct dummy {};
union {
dummy m_val;
unexpected<E> m_unexpect;
};
bool m_has_val;
};
// `T` is `void`, `E` is not trivially-destructible
template <class E> struct expected_storage_base<void, E, false, false> {
constexpr expected_storage_base() : m_dummy(), m_has_val(true) {}
constexpr expected_storage_base(no_init_t) : m_dummy(), m_has_val(false) {}
constexpr expected_storage_base(in_place_t) : m_dummy(), 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>();
}
}
union {
char m_dummy;
unexpected<E> m_unexpect;
};
bool m_has_val;
};
// This base class provides some handy member functions which can be used in
// further derived classes
template <class T, class E>
struct expected_operations_base : expected_storage_base<T, E> {
using expected_storage_base<T, E>::expected_storage_base;
template <class... Args> void construct(Args &&... args) noexcept {
new (std::addressof(this->m_val)) T(std::forward<Args>(args)...);
this->m_has_val = true;
}
template <class 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 <class... Args> void construct_error(Args &&... args) noexcept {
new (std::addressof(this->m_unexpect))
unexpected<E>(std::forward<Args>(args)...);
this->m_has_val = false;
}
#ifdef TL_EXPECTED_EXCEPTIONS_ENABLED
// These assign overloads ensure that the most efficient assignment
// implementation is used while maintaining the strong exception guarantee.
// The problematic case is where rhs has a value, but *this does not.
//
// This overload handles the case where we can just copy-construct `T`
// directly into place without throwing.
template <class U = T,
detail::enable_if_t<std::is_nothrow_copy_constructible<U>::value>
* = nullptr>
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);
}
}
// This overload handles the case where we can attempt to create a copy of
// `T`, then no-throw move it into place if the copy was successful.
template <class U = T,
detail::enable_if_t<!std::is_nothrow_copy_constructible<U>::value &&
std::is_nothrow_move_constructible<U>::value>
* = nullptr>
void assign(const expected_operations_base &rhs) noexcept {
if (!this->m_has_val && rhs.m_has_val) {
T tmp = rhs.get();
geterr().~unexpected<E>();
construct(std::move(tmp));
} else {
assign_common(rhs);
}
}
// This overload is the worst-case, where we have to move-construct the
// unexpected value into temporary storage, then try to copy the T into place.
// If the construction succeeds, then everything is fine, but if it throws,
// then we move the old unexpected value back into place before rethrowing the
// exception.
template <class U = T,
detail::enable_if_t<!std::is_nothrow_copy_constructible<U>::value &&
!std::is_nothrow_move_constructible<U>::value>
* = nullptr>
void assign(const expected_operations_base &rhs) {
if (!this->m_has_val && rhs.m_has_val) {
auto tmp = std::move(geterr());
geterr().~unexpected<E>();
try {
construct(rhs.get());
} catch (...) {
geterr() = std::move(tmp);
throw;
}
} else {
assign_common(rhs);
}
}
// These overloads do the same as above, but for rvalues
template <class U = T,
detail::enable_if_t<std::is_nothrow_move_constructible<U>::value>
* = nullptr>
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(std::move(rhs));
}
}
template <class U = T,
detail::enable_if_t<!std::is_nothrow_move_constructible<U>::value>
* = nullptr>
void assign(expected_operations_base &&rhs) {
if (!this->m_has_val && rhs.m_has_val) {
auto tmp = std::move(geterr());
geterr().~unexpected<E>();
try {
construct(std::move(rhs).get());
} catch (...) {
geterr() = std::move(tmp);
throw;
}
} else {
assign_common(std::move(rhs));
}
}
#else
// If exceptions are disabled then we can just copy-construct
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);
}
}
#endif
// The common part of move/copy assigning
template <class 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; }
TL_EXPECTED_11_CONSTEXPR T &get() & { return this->m_val; }
constexpr const T &get() const & { return this->m_val; }
TL_EXPECTED_11_CONSTEXPR T &&get() && { return std::move(this->m_val); }
#ifndef TL_EXPECTED_NO_CONSTRR
constexpr const T &&get() const && { return std::move(this->m_val); }
#endif
TL_EXPECTED_11_CONSTEXPR unexpected<E> &geterr() & {
return this->m_unexpect;
}
constexpr const unexpected<E> &geterr() const & { return this->m_unexpect; }
TL_EXPECTED_11_CONSTEXPR unexpected<E> &&geterr() && {
return std::move(this->m_unexpect);
}
#ifndef TL_EXPECTED_NO_CONSTRR
constexpr const unexpected<E> &&geterr() const && {
return std::move(this->m_unexpect);
}
#endif
constexpr void destroy_val() {
get().~T();
}
};
// This base class provides some handy member functions which can be used in
// further derived classes
template <class E>
struct expected_operations_base<void, E> : expected_storage_base<void, E> {
using expected_storage_base<void, E>::expected_storage_base;
template <class... Args> void construct() noexcept { this->m_has_val = true; }
// This function doesn't use its argument, but needs it so that code in
// levels above this can work independently of whether T is void
template <class Rhs> void construct_with(Rhs &&) noexcept {
this->m_has_val = true;
}
template <class... Args> void construct_error(Args &&... args) noexcept {
new (std::addressof(this->m_unexpect))
unexpected<E>(std::forward<Args>(args)...);
this->m_has_val = false;
}
template <class Rhs> void assign(Rhs &&rhs) noexcept {
if (!this->m_has_val) {
if (rhs.m_has_val) {
geterr().~unexpected<E>();
construct();
} else {
geterr() = std::forward<Rhs>(rhs).geterr();
}
} else {
if (!rhs.m_has_val) {
construct_error(std::forward<Rhs>(rhs).geterr());
}
}
}
bool has_value() const { return this->m_has_val; }
TL_EXPECTED_11_CONSTEXPR unexpected<E> &geterr() & {
return this->m_unexpect;
}
constexpr const unexpected<E> &geterr() const & { return this->m_unexpect; }
TL_EXPECTED_11_CONSTEXPR unexpected<E> &&geterr() && {
return std::move(this->m_unexpect);
}
#ifndef TL_EXPECTED_NO_CONSTRR
constexpr const unexpected<E> &&geterr() const && {
return std::move(this->m_unexpect);
}
#endif
constexpr void destroy_val() {
//no-op
}
};
// This class manages conditionally having a trivial copy constructor
// This specialization is for when T and E are trivially copy constructible
template <class T, class E,
bool = is_void_or<T, TL_EXPECTED_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T)>::
value &&TL_EXPECTED_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(E)::value>
struct expected_copy_base : expected_operations_base<T, E> {
using expected_operations_base<T, E>::expected_operations_base;
};
// This specialization is for when T or E are not trivially copy constructible
template <class T, class 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) {
if (rhs.has_value()) {
this->construct_with(rhs);
} else {
this->construct_error(rhs.geterr());
}
}
expected_copy_base(expected_copy_base &&rhs) = default;
expected_copy_base &operator=(const expected_copy_base &rhs) = default;
expected_copy_base &operator=(expected_copy_base &&rhs) = default;
};
// This class manages conditionally having a trivial move constructor
// Unfortunately there's no way to achieve this in GCC < 5 AFAIK, since it
// doesn't implement an analogue to std::is_trivially_move_constructible. We
// have to make do with a non-trivial move constructor even if T is trivially
// move constructible
#ifndef TL_EXPECTED_GCC49
template <class T, class E,
bool = is_void_or<T, std::is_trivially_move_constructible<T>>::value
&&std::is_trivially_move_constructible<E>::value>
struct expected_move_base : expected_copy_base<T, E> {
using expected_copy_base<T, E>::expected_copy_base;
};
#else
template <class T, class E, bool = false> struct expected_move_base;
#endif
template <class T, class 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 &rhs) = default;
expected_move_base(expected_move_base &&rhs) noexcept(
std::is_nothrow_move_constructible<T>::value)
: expected_copy_base<T, E>(no_init) {
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 &rhs) = default;
expected_move_base &operator=(expected_move_base &&rhs) = default;
};
// This class manages conditionally having a trivial copy assignment operator
template <class T, class E,
bool = is_void_or<
T, conjunction<TL_EXPECTED_IS_TRIVIALLY_COPY_ASSIGNABLE(T),
TL_EXPECTED_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T),
TL_EXPECTED_IS_TRIVIALLY_DESTRUCTIBLE(T)>>::value
&&TL_EXPECTED_IS_TRIVIALLY_COPY_ASSIGNABLE(E)::value
&&TL_EXPECTED_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(E)::value
&&TL_EXPECTED_IS_TRIVIALLY_DESTRUCTIBLE(E)::value>
struct expected_copy_assign_base : expected_move_base<T, E> {
using expected_move_base<T, E>::expected_move_base;
};
template <class T, class 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 &rhs) = default;
expected_copy_assign_base(expected_copy_assign_base &&rhs) = 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 &&rhs) = default;
};
// This class manages conditionally having a trivial move assignment operator
// Unfortunately there's no way to achieve this in GCC < 5 AFAIK, since it
// doesn't implement an analogue to std::is_trivially_move_assignable. We have
// to make do with a non-trivial move assignment operator even if T is trivially
// move assignable
#ifndef TL_EXPECTED_GCC49
template <class T, class E,
bool =
is_void_or<T, conjunction<std::is_trivially_destructible<T>,
std::is_trivially_move_constructible<T>,
std::is_trivially_move_assignable<T>>>::
value &&std::is_trivially_destructible<E>::value
&&std::is_trivially_move_constructible<E>::value
&&std::is_trivially_move_assignable<E>::value>
struct expected_move_assign_base : expected_copy_assign_base<T, E> {
using expected_copy_assign_base<T, E>::expected_copy_assign_base;
};
#else
template <class T, class E, bool = false> struct expected_move_assign_base;
#endif
template <class T, class 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 &rhs) = default;
expected_move_assign_base(expected_move_assign_base &&rhs) = default;
expected_move_assign_base &
operator=(const expected_move_assign_base &rhs) = default;
expected_move_assign_base &
operator=(expected_move_assign_base &&rhs) noexcept(
std::is_nothrow_move_constructible<T>::value
&&std::is_nothrow_move_assignable<T>::value) {
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
template <class T, class E,
bool EnableCopy = (is_copy_constructible_or_void<T>::value &&
std::is_copy_constructible<E>::value),
bool EnableMove = (is_move_constructible_or_void<T>::value &&
std::is_move_constructible<E>::value)>
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 <class T, class 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 <class T, class 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 <class T, class 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
// constructors depending on whether T and E are copy/move constructible +
// assignable
template <class T, class E,
bool EnableCopy = (is_copy_constructible_or_void<T>::value &&
std::is_copy_constructible<E>::value &&
is_copy_assignable_or_void<T>::value &&
std::is_copy_assignable<E>::value),
bool EnableMove = (is_move_constructible_or_void<T>::value &&
std::is_move_constructible<E>::value &&
is_move_assignable_or_void<T>::value &&
std::is_move_assignable<E>::value)>
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 <class T, class 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 <class T, class 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 <class T, class 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 {
explicit constexpr default_constructor_tag() = default;
};
// expected_default_ctor_base will ensure that expected has a deleted default
// consturctor if T is not default constructible.
// This specialization is for when T is default constructible
template <class T, class E,
bool Enable =
std::is_default_constructible<T>::value || std::is_void<T>::value>
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) {}
};
// This specialization is for when T is not default constructible
template <class T, class 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) {}
};
} // namespace detail
template <class E> class bad_expected_access : public std::exception {
public:
explicit bad_expected_access(E e) : m_val(std::move(e)) {}
virtual const char *what() const noexcept override {
return "Bad expected access";
}
const E &error() const & { return m_val; }
E &error() & { return m_val; }
const E &&error() const && { return std::move(m_val); }
E &&error() && { return std::move(m_val); }
private:
E m_val;
};
/// An `expected<T, E>` object is an object that contains the storage for
/// another object and manages the lifetime of this contained object `T`.
/// Alternatively it could contain the storage for another unexpected object
/// `E`. The contained object may not be initialized after the expected object
/// has been initialized, and may not be destroyed before the expected object
/// has been destroyed. The initialization state of the contained object is
/// tracked by the expected object.
template <class T, class 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> {
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");
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 <class U = T,
detail::enable_if_t<!std::is_void<U>::value> * = nullptr>
U &val() {
return this->m_val;
}
unexpected<E> &err() { return this->m_unexpect; }
template <class U = T,
detail::enable_if_t<!std::is_void<U>::value> * = nullptr>
const U &val() const {
return this->m_val;
}
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>;
public:
typedef T value_type;
typedef E error_type;
typedef unexpected<E> unexpected_type;
#if defined(TL_EXPECTED_CXX14) && !defined(TL_EXPECTED_GCC49) && \
!defined(TL_EXPECTED_GCC54) && !defined(TL_EXPECTED_GCC55)
/// \group and_then
/// Carries out some operation which returns an expected on the stored object
/// if there is one. \requires `std::invoke(std::forward<F>(f), value())`
/// returns an `expected<U>` for some `U`. \returns Let `U` be the result
/// of `std::invoke(std::forward<F>(f), value())`. Returns an
/// `expected<U>`. The return value is empty if `*this` is empty,
/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
/// is returned.
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
template <class F> TL_EXPECTED_11_CONSTEXPR auto and_then(F &&f) & {
return and_then_impl(*this, std::forward<F>(f));
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
template <class F> TL_EXPECTED_11_CONSTEXPR auto and_then(F &&f) && {
return and_then_impl(std::move(*this), std::forward<F>(f));
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &;
template <class F> constexpr auto and_then(F &&f) const & {
return and_then_impl(*this, std::forward<F>(f));
}
#ifndef TL_EXPECTED_NO_CONSTRR
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
template <class F> constexpr auto and_then(F &&f) const && {
return and_then_impl(std::move(*this), std::forward<F>(f));
}
#endif
#else
/// \group and_then
/// Carries out some operation which returns an expected on the stored object
/// if there is one. \requires `std::invoke(std::forward<F>(f), value())`
/// returns an `expected<U>` for some `U`. \returns Let `U` be the result
/// of `std::invoke(std::forward<F>(f), value())`. Returns an
/// `expected<U>`. The return value is empty if `*this` is empty,
/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
/// is returned.
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
template <class F>
TL_EXPECTED_11_CONSTEXPR auto
and_then(F &&f) & -> decltype(and_then_impl(*this, std::forward<F>(f))) {
return and_then_impl(*this, std::forward<F>(f));
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
template <class F>
TL_EXPECTED_11_CONSTEXPR auto and_then(F &&f) && -> decltype(
and_then_impl(std::move(*this), std::forward<F>(f))) {
return and_then_impl(std::move(*this), std::forward<F>(f));
}
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &;
template <class F>
constexpr auto and_then(F &&f) const & -> decltype(
and_then_impl(*this, std::forward<F>(f))) {
return and_then_impl(*this, std::forward<F>(f));
}
#ifndef TL_EXPECTED_NO_CONSTRR
/// \group and_then
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
template <class F>
constexpr auto and_then(F &&f) const && -> decltype(
and_then_impl(std::move(*this), std::forward<F>(f))) {
return and_then_impl(std::move(*this), std::forward<F>(f));
}
#endif
#endif
#if defined(TL_EXPECTED_CXX14) && !defined(TL_EXPECTED_GCC49) && \
!defined(TL_EXPECTED_GCC54) && !defined(TL_EXPECTED_GCC55)
/// \brief Carries out some operation on the stored object if there is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. If `U` is `void`, returns an `expected<monostate,E>, otherwise
// returns an `expected<U,E>`. If `*this` is unexpected, the
/// result is `*this`, otherwise an `expected<U,E>` is constructed from the
/// return value of `std::invoke(std::forward<F>(f), value())` and is
/// returned.
///
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) &;
template <class F> TL_EXPECTED_11_CONSTEXPR auto map(F &&f) & {
return expected_map_impl(*this, std::forward<F>(f));
}
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) &&;
template <class F> TL_EXPECTED_11_CONSTEXPR auto map(F &&f) && {
return expected_map_impl(std::move(*this), std::forward<F>(f));
}
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) const &;
template <class F> constexpr auto map(F &&f) const & {
return expected_map_impl(*this, std::forward<F>(f));
}
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) const &&;
template <class F> constexpr auto map(F &&f) const && {
return expected_map_impl(std::move(*this), std::forward<F>(f));
}
#else
/// \brief Carries out some operation on the stored object if there is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. If `U` is `void`, returns an `expected<monostate,E>, otherwise
// returns an `expected<U,E>`. If `*this` is unexpected, the
/// result is `*this`, otherwise an `expected<U,E>` is constructed from the
/// return value of `std::invoke(std::forward<F>(f), value())` and is
/// returned.
///
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) &;
template <class F>
TL_EXPECTED_11_CONSTEXPR decltype(
expected_map_impl(std::declval<expected &>(), std::declval<F &&>()))
map(F &&f) & {
return expected_map_impl(*this, std::forward<F>(f));
}
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) &&;
template <class F>
TL_EXPECTED_11_CONSTEXPR decltype(
expected_map_impl(std::declval<expected>(), std::declval<F &&>()))
map(F &&f) && {
return expected_map_impl(std::move(*this), std::forward<F>(f));
}
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) const &;
template <class F>
constexpr decltype(expected_map_impl(std::declval<const expected &>(),
std::declval<F &&>()))
map(F &&f) const & {
return expected_map_impl(*this, std::forward<F>(f));
}
#ifndef TL_EXPECTED_NO_CONSTRR
/// \group map
/// \synopsis template <class F> constexpr auto map(F &&f) const &&;
template <class F>
constexpr decltype(expected_map_impl(std::declval<const expected &&>(),
std::declval<F &&>()))
map(F &&f) const && {
return expected_map_impl(std::move(*this), std::forward<F>(f));
}
#endif
#endif
#if defined(TL_EXPECTED_CXX14) && !defined(TL_EXPECTED_GCC49) && \
!defined(TL_EXPECTED_GCC54) && !defined(TL_EXPECTED_GCC55)
/// \brief Carries out some operation on the stored unexpected object if there
/// is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. If `U` is `void`, returns an `expected<T,monostate>`, otherwise
/// returns an `expected<T,U>`. If `*this` has an expected
/// value, the result is `*this`, otherwise an `expected<T,U>` is constructed
/// from `make_unexpected(std::invoke(std::forward<F>(f), value()))` and is
/// returned.
///
/// \group map_error
/// \synopsis template <class F> constexpr auto map_error(F &&f) &;
template <class F> TL_EXPECTED_11_CONSTEXPR auto map_error(F &&f) & {
return map_error_impl(*this, std::forward<F>(f));
}
/// \group map_error
/// \synopsis template <class F> constexpr auto map_error(F &&f) &&;
template <class F> TL_EXPECTED_11_CONSTEXPR auto map_error(F &&f) && {
return map_error_impl(std::move(*this), std::forward<F>(f));
}
/// \group map_error
/// \synopsis template <class F> constexpr auto map_error(F &&f) const &;
template <class F> constexpr auto map_error(F &&f) const & {
return map_error_impl(*this, std::forward<F>(f));
}
/// \group map_error
/// \synopsis template <class F> constexpr auto map_error(F &&f) const &&;
template <class F> constexpr auto map_error(F &&f) const && {
return map_error_impl(std::move(*this), std::forward<F>(f));
}
#else
/// \brief Carries out some operation on the stored unexpected object if there
/// is one.
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
/// value())`. Returns an `expected<T,U>`. If `*this` has an expected
/// value, the result is `*this`, otherwise an `expected<T,U>` is constructed
/// from `make_unexpected(std::invoke(std::forward<F>(f), value()))` and is
/// returned.
///
/// \group map_error
/// \synopsis template <class F> constexpr auto map_error(F &&f) &;
template <class F>
TL_EXPECTED_11_CONSTEXPR decltype(map_error_impl(std::declval<expected &>(),
std::declval<F &&>()))
map_error(F &&f) & {
return map_error_impl(*this, std::forward<F>(f));
}
/// \group map_error
/// \synopsis template <class F> constexpr auto map_error(F &&f) &&;
template <class F>
TL_EXPECTED_11_CONSTEXPR decltype(map_error_impl(std::declval<expected &&>(),
std::declval<F &&>()))
map_error(F &&f) && {
return map_error_impl(std::move(*this), std::forward<F>(f));
}
/// \group map_error
/// \synopsis template <class F> constexpr auto map_error(F &&f) const &;
template <class F>
constexpr decltype(map_error_impl(std::declval<const expected &>(),
std::declval<F &&>()))
map_error(F &&f) const & {
return map_error_impl(*this, std::forward<F>(f));
}
#ifndef TL_EXPECTED_NO_CONSTRR
/// \group map_error
/// \synopsis template <class F> constexpr auto map_error(F &&f) const &&;
template <class F>
constexpr decltype(map_error_impl(std::declval<const expected &&>(),
std::declval<F &&>()))
map_error(F &&f) const && {
return map_error_impl(std::move(*this), std::forward<F>(f));
}
#endif
#endif
/// \brief Calls `f` if the expectd is in the unexpected state
/// \requires `F` is invokable with `E`, and `std::invoke_result_t<F>`
/// must be void or convertible to `expcted<T,E>`.
/// \effects If `*this` has a value, returns `*this`.
/// Otherwise, if `f` returns `void`, calls `std::forward<F>(f)(E)` and returns
/// `std::nullopt`. Otherwise, returns `std::forward<F>(f)(E)`.
///
/// \group or_else
template <class F> expected TL_EXPECTED_11_CONSTEXPR or_else(F &&f) & {
return or_else_impl(*this, std::forward<F>(f));
}
template <class F> expected TL_EXPECTED_11_CONSTEXPR or_else(F &&f) && {
return or_else_impl(std::move(*this), std::forward<F>(f));
}
template <class F> expected constexpr or_else(F &&f) const & {
return or_else_impl(*this, std::forward<F>(f));
}
#ifndef TL_EXPECTED_NO_CONSTRR
template <class F> expected constexpr or_else(F &&f) const && {
return or_else_impl(std::move(*this), std::forward<F>(f));
}
#endif
constexpr expected() = default;
constexpr expected(const expected &rhs) = default;
constexpr expected(expected &&rhs) = default;
expected &operator=(const expected &rhs) = default;
expected &operator=(expected &&rhs) = default;
template <class... Args,
detail::enable_if_t<std::is_constructible<T, Args &&...>::value> * =
nullptr>
constexpr expected(in_place_t, Args &&... args)
: impl_base(in_place, std::forward<Args>(args)...),
ctor_base(detail::default_constructor_tag{}) {}
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)
: impl_base(in_place, il, std::forward<Args>(args)...),
ctor_base(detail::default_constructor_tag{}) {}
/// \group unexpected_ctor
/// \synopsis EXPLICIT constexpr expected(const unexpected<G> &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>
explicit constexpr expected(const unexpected<G> &e)
: impl_base(unexpect, e.value()),
ctor_base(detail::default_constructor_tag{}) {}
/// \exclude
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)
: impl_base(unexpect, e.value()),
ctor_base(detail::default_constructor_tag{}) {}
/// \group unexpected_ctor
/// \synopsis EXPLICIT constexpr expected(unexpected<G> &&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)
: impl_base(unexpect, std::move(e.value())),
ctor_base(detail::default_constructor_tag{}) {}
/// \exclude
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)
: impl_base(unexpect, std::move(e.value())),
ctor_base(detail::default_constructor_tag{}) {}
template <class... Args,
detail::enable_if_t<std::is_constructible<E, Args &&...>::value> * =
nullptr>
constexpr explicit expected(unexpect_t, Args &&... args)
: impl_base(unexpect, std::forward<Args>(args)...),
ctor_base(detail::default_constructor_tag{}) {}
/// \exclude
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)
: impl_base(unexpect, il, std::forward<Args>(args)...),
ctor_base(detail::default_constructor_tag{}) {}
template <class U, class G,
detail::enable_if_t<!(std::is_convertible<U const &, T>::value &&
std::is_convertible<G const &, E>::value)> * =
nullptr,
detail::expected_enable_from_other<T, E, U, G, const U &, const G &>
* = nullptr>
explicit TL_EXPECTED_11_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());
}
}
/// \exclude
template <class U, class G,
detail::enable_if_t<(std::is_convertible<U const &, T>::value &&
std::is_convertible<G const &, E>::value)> * =
nullptr,
detail::expected_enable_from_other<T, E, U, G, const U &, const G &>
* = nullptr>
TL_EXPECTED_11_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 <
class U, class G,
detail::enable_if_t<!(std::is_convertible<U &&, T>::value &&
std::is_convertible<G &&, E>::value)> * = nullptr,
detail::expected_enable_from_other<T, E, U, G, U &&, G &&> * = nullptr>
explicit TL_EXPECTED_11_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()));
}
}
/// \exclude
template <
class U, class G,
detail::enable_if_t<(std::is_convertible<U &&, T>::value &&
std::is_convertible<G &&, E>::value)> * = nullptr,
detail::expected_enable_from_other<T, E, U, G, U &&, G &&> * = nullptr>
TL_EXPECTED_11_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 <
class U = T,
detail::enable_if_t<!std::is_convertible<U &&, T>::value> * = nullptr,
detail::expected_enable_forward_value<T, E, U> * = nullptr>
explicit TL_EXPECTED_MSVC2015_CONSTEXPR expected(U &&v)
: expected(in_place, std::forward<U>(v)) {}
/// \exclude
template <
class U = T,
detail::enable_if_t<std::is_convertible<U &&, T>::value> * = nullptr,
detail::expected_enable_forward_value<T, E, U> * = nullptr>
TL_EXPECTED_MSVC2015_CONSTEXPR expected(U &&v)
: expected(in_place, std::forward<U>(v)) {}
template <
class U = T, class G = T,
detail::enable_if_t<std::is_nothrow_constructible<T, U &&>::value> * =
nullptr,
detail::enable_if_t<!std::is_void<G>::value> * = nullptr,
detail::enable_if_t<
(!std::is_same<expected<T, E>, detail::decay_t<U>>::value &&
!detail::conjunction<std::is_scalar<T>,
std::is_same<T, detail::decay_t<U>>>::value &&
std::is_constructible<T, U>::value &&
std::is_assignable<G &, U>::value &&
std::is_nothrow_move_constructible<E>::value)> * = 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;
}
/// \exclude
template <
class U = T, class G = T,
detail::enable_if_t<!std::is_nothrow_constructible<T, U &&>::value> * =
nullptr,
detail::enable_if_t<!std::is_void<U>::value> * = nullptr,
detail::enable_if_t<
(!std::is_same<expected<T, E>, detail::decay_t<U>>::value &&
!detail::conjunction<std::is_scalar<T>,
std::is_same<T, detail::decay_t<U>>>::value &&
std::is_constructible<T, U>::value &&
std::is_assignable<G &, U>::value &&
std::is_nothrow_move_constructible<E>::value)> * = nullptr>
expected &operator=(U &&v) {
if (has_value()) {
val() = std::forward<U>(v);
} else {
auto tmp = std::move(err());
err().~unexpected<E>();
#ifdef TL_EXPECTED_EXCEPTIONS_ENABLED
try {
::new (valptr()) T(std::move(v));
this->m_has_val = true;
} catch (...) {
err() = std::move(tmp);
throw;
}
#else
::new (valptr()) T(std::move(v));
this->m_has_val = true;
#endif
}
return *this;
}
template <class G = E,
detail::enable_if_t<std::is_nothrow_copy_constructible<G>::value &&
std::is_assignable<G &, G>::value> * = 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 <class G = E,
detail::enable_if_t<std::is_nothrow_move_constructible<G>::value &&
std::is_move_assignable<G>::value> * = 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 <class... Args, detail::enable_if_t<std::is_nothrow_constructible<
T, Args &&...>::value> * = 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;
}
}
/// \exclude
template <class... Args, detail::enable_if_t<!std::is_nothrow_constructible<
T, Args &&...>::value> * = nullptr>
void emplace(Args &&... args) {
if (has_value()) {
val() = T(std::forward<Args>(args)...);
} else {
auto tmp = std::move(err());
err().~unexpected<E>();
#ifdef TL_EXPECTED_EXCEPTIONS_ENABLED
try {
::new (valptr()) T(std::forward<Args>(args)...);
this->m_has_val = true;
} catch (...) {
err() = std::move(tmp);
throw;
}
#else
::new (valptr()) T(std::forward<Args>(args)...);
this->m_has_val = true;
#endif
}
}
template <class U, class... Args,
detail::enable_if_t<std::is_nothrow_constructible<
T, std::initializer_list<U> &, Args &&...>::value> * = 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;
}
}
/// \exclude
template <class U, class... Args,
detail::enable_if_t<!std::is_nothrow_constructible<
T, std::initializer_list<U> &, Args &&...>::value> * = 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>();
#ifdef TL_EXPECTED_EXCEPTIONS_ENABLED
try {
::new (valptr()) T(il, std::forward<Args>(args)...);
this->m_has_val = true;
} catch (...) {
err() = std::move(tmp);
throw;
}
#else
::new (valptr()) T(il, std::forward<Args>(args)...);
this->m_has_val = true;
#endif
}
}
// 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);
}
}
/// \returns a pointer to the stored value
/// \requires a value is stored
/// \group pointer
constexpr const T *operator->() const { return valptr(); }
/// \group pointer
TL_EXPECTED_11_CONSTEXPR T *operator->() { return valptr(); }
/// \returns the stored value
/// \requires a value is stored
/// \group deref
template <class U = T,
detail::enable_if_t<!std::is_void<U>::value> * = nullptr>
constexpr const U &operator*() const & {
return val();
}
/// \group deref
template <class U = T,
detail::enable_if_t<!std::is_void<U>::value> * = nullptr>
TL_EXPECTED_11_CONSTEXPR U &operator*() & {
return val();
}
/// \group deref
template <class U = T,
detail::enable_if_t<!std::is_void<U>::value> * = nullptr>
constexpr const U &&operator*() const && {
return std::move(val());
}
/// \group deref
template <class U = T,
detail::enable_if_t<!std::is_void<U>::value> * = nullptr>
TL_EXPECTED_11_CONSTEXPR U &&operator*() && {
return std::move(val());
}
/// \returns whether or not the optional has a value
/// \group has_value
constexpr bool has_value() const noexcept { return this->m_has_val; }
/// \group has_value
constexpr explicit operator bool() const noexcept { return this->m_has_val; }
/// \returns the contained value if there is one, otherwise throws
/// [bad_expected_access]
///
/// \group value
template <class U = T,
detail::enable_if_t<!std::is_void<U>::value> * = nullptr>
TL_EXPECTED_11_CONSTEXPR const U &value() const & {
if (!has_value())
detail::throw_exception(bad_expected_access<E>(err().value()));
return val();
}
/// \group value
template <class U = T,
detail::enable_if_t<!std::is_void<U>::value> * = nullptr>
TL_EXPECTED_11_CONSTEXPR U &value() & {
if (!has_value())
detail::throw_exception(bad_expected_access<E>(err().value()));
return val();
}
/// \group value
template <class U = T,
detail::enable_if_t<!std::is_void<U>::value> * = nullptr>
TL_EXPECTED_11_CONSTEXPR const U &&value() const && {
if (!has_value())
detail::throw_exception(bad_expected_access<E>(err().value()));
return std::move(val());
}
/// \group value
template <class U = T,
detail::enable_if_t<!std::is_void<U>::value> * = nullptr>
TL_EXPECTED_11_CONSTEXPR U &&value() && {
if (!has_value())
detail::throw_exception(bad_expected_access<E>(err().value()));
return std::move(val());
}
/// \returns the unexpected value
/// \requires there is an unexpected value
/// \group error
constexpr const E &error() const & { return err().value(); }
/// \group error
TL_EXPECTED_11_CONSTEXPR E &error() & { return err().value(); }
/// \group error
constexpr const E &&error() const && { return std::move(err().value()); }
/// \group error
TL_EXPECTED_11_CONSTEXPR E &&error() && { return std::move(err().value()); }
/// \returns the stored value if there is one, otherwise returns `u`
/// \group value_or
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));
}
/// \group value_or
template <class U> TL_EXPECTED_11_CONSTEXPR 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));
}
};
/// \exclude
namespace detail {
template <class Exp> using exp_t = typename detail::decay_t<Exp>::value_type;
template <class Exp> using err_t = typename detail::decay_t<Exp>::error_type;
template <class Exp, class Ret> using ret_t = expected<Ret, err_t<Exp>>;
#ifdef TL_EXPECTED_CXX14
template <class Exp, class F,
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>()))>
constexpr auto and_then_impl(Exp &&exp, F &&f) {
static_assert(detail::is_expected<Ret>::value, "F must return an expected");
return exp.has_value()
? detail::invoke(std::forward<F>(f), *std::forward<Exp>(exp))
: Ret(unexpect, exp.error());
}
template <class Exp, class F,
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>()))>
constexpr auto and_then_impl(Exp &&exp, F &&f) {
static_assert(detail::is_expected<Ret>::value, "F must return an expected");
return exp.has_value() ? detail::invoke(std::forward<F>(f))
: Ret(unexpect, exp.error());
}
#else
template <class> struct TC;
template <class Exp, class F,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>())),
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr>
auto and_then_impl(Exp &&exp, F &&f) -> Ret {
static_assert(detail::is_expected<Ret>::value, "F must return an expected");
return exp.has_value()
? detail::invoke(std::forward<F>(f), *std::forward<Exp>(exp))
: Ret(unexpect, exp.error());
}
template <class Exp, class F,
class Ret = decltype(detail::invoke(std::declval<F>())),
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr>
constexpr auto and_then_impl(Exp &&exp, F &&f) -> Ret {
static_assert(detail::is_expected<Ret>::value, "F must return an expected");
return exp.has_value() ? detail::invoke(std::forward<F>(f))
: Ret(unexpect, exp.error());
}
#endif
#ifdef TL_EXPECTED_CXX14
template <class Exp, class F,
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto expected_map_impl(Exp &&exp, F &&f) {
using result = ret_t<Exp, detail::decay_t<Ret>>;
return exp.has_value() ? result(detail::invoke(std::forward<F>(f),
*std::forward<Exp>(exp)))
: result(unexpect, std::forward<Exp>(exp).error());
}
template <class Exp, class F,
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
auto expected_map_impl(Exp &&exp, F &&f) {
using result = expected<void, err_t<Exp>>;
if (exp.has_value()) {
detail::invoke(std::forward<F>(f), *std::forward<Exp>(exp));
return result();
}
return result(unexpect, std::forward<Exp>(exp).error());
}
template <class Exp, class F,
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto expected_map_impl(Exp &&exp, F &&f) {
using result = ret_t<Exp, detail::decay_t<Ret>>;
return exp.has_value() ? result(detail::invoke(std::forward<F>(f)))
: result(unexpect, std::forward<Exp>(exp).error());
}
template <class Exp, class F,
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
auto expected_map_impl(Exp &&exp, F &&f) {
using result = expected<void, err_t<Exp>>;
if (exp.has_value()) {
detail::invoke(std::forward<F>(f));
return result();
}
return result(unexpect, std::forward<Exp>(exp).error());
}
#else
template <class Exp, class F,
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto expected_map_impl(Exp &&exp, F &&f)
-> ret_t<Exp, detail::decay_t<Ret>> {
using result = ret_t<Exp, detail::decay_t<Ret>>;
return exp.has_value() ? result(detail::invoke(std::forward<F>(f),
*std::forward<Exp>(exp)))
: result(unexpect, std::forward<Exp>(exp).error());
}
template <class Exp, class F,
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
*std::declval<Exp>())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
auto expected_map_impl(Exp &&exp, F &&f) -> expected<void, err_t<Exp>> {
if (exp.has_value()) {
detail::invoke(std::forward<F>(f), *std::forward<Exp>(exp));
return {};
}
return unexpected<err_t<Exp>>(std::forward<Exp>(exp).error());
}
template <class Exp, class F,
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto expected_map_impl(Exp &&exp, F &&f)
-> ret_t<Exp, detail::decay_t<Ret>> {
using result = ret_t<Exp, detail::decay_t<Ret>>;
return exp.has_value() ? result(detail::invoke(std::forward<F>(f)))
: result(unexpect, std::forward<Exp>(exp).error());
}
template <class Exp, class F,
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
auto expected_map_impl(Exp &&exp, F &&f) -> expected<void, err_t<Exp>> {
if (exp.has_value()) {
detail::invoke(std::forward<F>(f));
return {};
}
return unexpected<err_t<Exp>>(std::forward<Exp>(exp).error());
}
#endif
#if defined(TL_EXPECTED_CXX14) && !defined(TL_EXPECTED_GCC49) && \
!defined(TL_EXPECTED_GCC54) && !defined(TL_EXPECTED_GCC55)
template <class Exp, class F,
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto map_error_impl(Exp &&exp, F &&f) {
using result = expected<exp_t<Exp>, detail::decay_t<Ret>>;
return exp.has_value()
? result(*std::forward<Exp>(exp))
: result(unexpect, detail::invoke(std::forward<F>(f),
std::forward<Exp>(exp).error()));
}
template <class Exp, class F,
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
auto map_error_impl(Exp &&exp, F &&f) {
using result = expected<exp_t<Exp>, monostate>;
if (exp.has_value()) {
return result(*std::forward<Exp>(exp));
}
detail::invoke(std::forward<F>(f), std::forward<Exp>(exp).error());
return result(unexpect, monostate{});
}
template <class Exp, class F,
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto map_error_impl(Exp &&exp, F &&f) {
using result = expected<exp_t<Exp>, detail::decay_t<Ret>>;
return exp.has_value()
? result()
: result(unexpect, detail::invoke(std::forward<F>(f),
std::forward<Exp>(exp).error()));
}
template <class Exp, class F,
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
auto map_error_impl(Exp &&exp, F &&f) {
using result = expected<exp_t<Exp>, monostate>;
if (exp.has_value()) {
return result();
}
detail::invoke(std::forward<F>(f), std::forward<Exp>(exp).error());
return result(unexpect, monostate{});
}
#else
template <class Exp, class F,
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto map_error_impl(Exp &&exp, F &&f)
-> expected<exp_t<Exp>, detail::decay_t<Ret>> {
using result = expected<exp_t<Exp>, detail::decay_t<Ret>>;
return exp.has_value()
? result(*std::forward<Exp>(exp))
: result(unexpect, detail::invoke(std::forward<F>(f),
std::forward<Exp>(exp).error()));
}
template <class Exp, class F,
detail::enable_if_t<!std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
auto map_error_impl(Exp &&exp, F &&f) -> expected<exp_t<Exp>, monostate> {
using result = expected<exp_t<Exp>, monostate>;
if (exp.has_value()) {
return result(*std::forward<Exp>(exp));
}
detail::invoke(std::forward<F>(f), std::forward<Exp>(exp).error());
return result(unexpect, monostate{});
}
template <class Exp, class F,
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto map_error_impl(Exp &&exp, F &&f)
-> expected<exp_t<Exp>, detail::decay_t<Ret>> {
using result = expected<exp_t<Exp>, detail::decay_t<Ret>>;
return exp.has_value()
? result()
: result(unexpect, detail::invoke(std::forward<F>(f),
std::forward<Exp>(exp).error()));
}
template <class Exp, class F,
detail::enable_if_t<std::is_void<exp_t<Exp>>::value> * = nullptr,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
auto map_error_impl(Exp &&exp, F &&f) -> expected<exp_t<Exp>, monostate> {
using result = expected<exp_t<Exp>, monostate>;
if (exp.has_value()) {
return result();
}
detail::invoke(std::forward<F>(f), std::forward<Exp>(exp).error());
return result(unexpect, monostate{});
}
#endif
#ifdef TL_EXPECTED_CXX14
template <class Exp, class F,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
constexpr auto or_else_impl(Exp &&exp, F &&f) {
static_assert(detail::is_expected<Ret>::value, "F must return an expected");
return exp.has_value()
? std::forward<Exp>(exp)
: detail::invoke(std::forward<F>(f), std::forward<Exp>(exp).error());
}
template <class Exp, class F,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
detail::decay_t<Exp> or_else_impl(Exp &&exp, F &&f) {
return exp.has_value()
? std::forward<Exp>(exp)
: (detail::invoke(std::forward<F>(f), std::forward<Exp>(exp).error()),
std::forward<Exp>(exp));
}
#else
template <class Exp, class F,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<!std::is_void<Ret>::value> * = nullptr>
auto or_else_impl(Exp &&exp, F &&f) -> Ret {
static_assert(detail::is_expected<Ret>::value, "F must return an expected");
return exp.has_value()
? std::forward<Exp>(exp)
: detail::invoke(std::forward<F>(f), std::forward<Exp>(exp).error());
}
template <class Exp, class F,
class Ret = decltype(detail::invoke(std::declval<F>(),
std::declval<Exp>().error())),
detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
detail::decay_t<Exp> or_else_impl(Exp &&exp, F &&f) {
return exp.has_value()
? std::forward<Exp>(exp)
: (detail::invoke(std::forward<F>(f), std::forward<Exp>(exp).error()),
std::forward<Exp>(exp));
}
#endif
} // namespace detail
template <class T, class E, class U, class 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 <class T, class E, class U, class F>
constexpr bool operator!=(const expected<T, E> &lhs,
const expected<U, F> &rhs) {
return (lhs.has_value() != rhs.has_value())
? true
: (!lhs.has_value() ? lhs.error() != rhs.error() : *lhs != *rhs);
}
template <class T, class E, class U>
constexpr bool operator==(const expected<T, E> &x, const U &v) {
return x.has_value() ? *x == v : false;
}
template <class T, class E, class U>
constexpr bool operator==(const U &v, const expected<T, E> &x) {
return x.has_value() ? *x == v : false;
}
template <class T, class E, class U>
constexpr bool operator!=(const expected<T, E> &x, const U &v) {
return x.has_value() ? *x != v : true;
}
template <class T, class E, class U>
constexpr bool operator!=(const U &v, const expected<T, E> &x) {
return x.has_value() ? *x != v : true;
}
template <class T, class E>
constexpr bool operator==(const expected<T, E> &x, const unexpected<E> &e) {
return x.has_value() ? false : x.error() == e.value();
}
template <class T, class E>
constexpr bool operator==(const unexpected<E> &e, const expected<T, E> &x) {
return x.has_value() ? false : x.error() == e.value();
}
template <class T, class E>
constexpr bool operator!=(const expected<T, E> &x, const unexpected<E> &e) {
return x.has_value() ? true : x.error() != e.value();
}
template <class T, class E>
constexpr bool operator!=(const unexpected<E> &e, const expected<T, E> &x) {
return x.has_value() ? true : x.error() != e.value();
}
// TODO is_swappable
template <class T, class E,
detail::enable_if_t<std::is_move_constructible<T>::value &&
std::is_move_constructible<E>::value> * = nullptr>
void swap(expected<T, E> &lhs,
expected<T, E> &rhs) noexcept(noexcept(lhs.swap(rhs))) {
lhs.swap(rhs);
}
} // namespace tl
#define TL_OPTIONAL_EXPECTED_MUTEX
#endif