2071 lines
69 KiB
C++
2071 lines
69 KiB
C++
///
|
|
// optional - An implementation of std::optional with extensions
|
|
// Written in 2017 by Sy Brand (tartanllama@gmail.com, @TartanLlama)
|
|
//
|
|
// Documentation available at https://tl.tartanllama.xyz/
|
|
//
|
|
// 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_OPTIONAL_HPP
|
|
#define TL_OPTIONAL_HPP
|
|
|
|
#define TL_OPTIONAL_VERSION_MAJOR 1
|
|
#define TL_OPTIONAL_VERSION_MINOR 0
|
|
#define TL_OPTIONAL_VERSION_PATCH 0
|
|
|
|
#include <exception>
|
|
#include <functional>
|
|
#include <new>
|
|
#include <type_traits>
|
|
#include <utility>
|
|
|
|
#if (defined(_MSC_VER) && _MSC_VER == 1900)
|
|
#define TL_OPTIONAL_MSVC2015
|
|
#endif
|
|
|
|
#if (defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 && \
|
|
!defined(__clang__))
|
|
#define TL_OPTIONAL_GCC49
|
|
#endif
|
|
|
|
#if (defined(__GNUC__) && __GNUC__ == 5 && __GNUC_MINOR__ <= 4 && \
|
|
!defined(__clang__))
|
|
#define TL_OPTIONAL_GCC54
|
|
#endif
|
|
|
|
#if (defined(__GNUC__) && __GNUC__ == 5 && __GNUC_MINOR__ <= 5 && \
|
|
!defined(__clang__))
|
|
#define TL_OPTIONAL_GCC55
|
|
#endif
|
|
|
|
#if (defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 && \
|
|
!defined(__clang__))
|
|
// GCC < 5 doesn't support overloading on const&& for member functions
|
|
#define TL_OPTIONAL_NO_CONSTRR
|
|
|
|
// GCC < 5 doesn't support some standard C++11 type traits
|
|
#define TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
|
|
std::has_trivial_copy_constructor<T>::value
|
|
#define TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) std::has_trivial_copy_assign<T>::value
|
|
|
|
// This one will be different for GCC 5.7 if it's ever supported
|
|
#define TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T) std::is_trivially_destructible<T>::value
|
|
|
|
// 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_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
|
|
tl::detail::is_trivially_copy_constructible<T>::value
|
|
#define TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
|
|
std::is_trivially_copy_assignable<T>::value
|
|
#define TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T) std::is_trivially_destructible<T>::value
|
|
#else
|
|
#define TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
|
|
std::is_trivially_copy_constructible<T>::value
|
|
#define TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
|
|
std::is_trivially_copy_assignable<T>::value
|
|
#define TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T) std::is_trivially_destructible<T>::value
|
|
#endif
|
|
|
|
#if __cplusplus > 201103L
|
|
#define TL_OPTIONAL_CXX14
|
|
#endif
|
|
|
|
// constexpr implies const in C++11, not C++14
|
|
#if (__cplusplus == 201103L || defined(TL_OPTIONAL_MSVC2015) || \
|
|
defined(TL_OPTIONAL_GCC49))
|
|
#define TL_OPTIONAL_11_CONSTEXPR
|
|
#else
|
|
#define TL_OPTIONAL_11_CONSTEXPR constexpr
|
|
#endif
|
|
|
|
namespace tl {
|
|
#ifndef TL_MONOSTATE_INPLACE_MUTEX
|
|
#define TL_MONOSTATE_INPLACE_MUTEX
|
|
/// Used to represent an optional with no data; essentially a bool
|
|
class monostate {};
|
|
|
|
/// A tag type to tell optional to construct its value in-place
|
|
struct in_place_t {
|
|
explicit in_place_t() = default;
|
|
};
|
|
/// A tag to tell optional to construct its value in-place
|
|
static constexpr in_place_t in_place{};
|
|
#endif
|
|
|
|
template <class T> class optional;
|
|
|
|
namespace detail {
|
|
#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 {};
|
|
|
|
#if defined(_LIBCPP_VERSION) && __cplusplus == 201103L
|
|
#define TL_TRAITS_LIBCXX_MEM_FN_WORKAROUND
|
|
#endif
|
|
|
|
// In C++11 mode, there's an issue in libc++'s std::mem_fn
|
|
// which results in a hard-error when using it in a noexcept expression
|
|
// in some cases. This is a check to workaround the common failing case.
|
|
#ifdef TL_TRAITS_LIBCXX_MEM_FN_WORKAROUND
|
|
template <class T> struct is_pointer_to_non_const_member_func : std::false_type {};
|
|
template <class T, class Ret, class... Args>
|
|
struct is_pointer_to_non_const_member_func<Ret(T::*) (Args...)> : std::true_type {};
|
|
template <class T, class Ret, class... Args>
|
|
struct is_pointer_to_non_const_member_func<Ret(T::*) (Args...)&> : std::true_type {};
|
|
template <class T, class Ret, class... Args>
|
|
struct is_pointer_to_non_const_member_func<Ret(T::*) (Args...)&&> : std::true_type {};
|
|
template <class T, class Ret, class... Args>
|
|
struct is_pointer_to_non_const_member_func<Ret(T::*) (Args...) volatile> : std::true_type {};
|
|
template <class T, class Ret, class... Args>
|
|
struct is_pointer_to_non_const_member_func<Ret(T::*) (Args...) volatile&> : std::true_type {};
|
|
template <class T, class Ret, class... Args>
|
|
struct is_pointer_to_non_const_member_func<Ret(T::*) (Args...) volatile&&> : std::true_type {};
|
|
|
|
template <class T> struct is_const_or_const_ref : std::false_type {};
|
|
template <class T> struct is_const_or_const_ref<T const&> : std::true_type {};
|
|
template <class T> struct is_const_or_const_ref<T const> : std::true_type {};
|
|
#endif
|
|
|
|
// std::invoke from C++17
|
|
// https://stackoverflow.com/questions/38288042/c11-14-invoke-workaround
|
|
template <typename Fn, typename... Args,
|
|
#ifdef TL_TRAITS_LIBCXX_MEM_FN_WORKAROUND
|
|
typename = enable_if_t<!(is_pointer_to_non_const_member_func<Fn>::value
|
|
&& is_const_or_const_ref<Args...>::value)>,
|
|
#endif
|
|
typename = enable_if_t<std::is_member_pointer<decay_t<Fn>>::value>,
|
|
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>>::value>>
|
|
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;
|
|
|
|
#if defined(_MSC_VER) && _MSC_VER <= 1900
|
|
// TODO make a version which works with MSVC 2015
|
|
template <class T, class U = T> struct is_swappable : std::true_type {};
|
|
|
|
template <class T, class U = T> struct is_nothrow_swappable : std::true_type {};
|
|
#else
|
|
// https://stackoverflow.com/questions/26744589/what-is-a-proper-way-to-implement-is-swappable-to-test-for-the-swappable-concept
|
|
namespace swap_adl_tests {
|
|
// if swap ADL finds this then it would call std::swap otherwise (same
|
|
// signature)
|
|
struct tag {};
|
|
|
|
template <class T> tag swap(T&, T&);
|
|
template <class T, std::size_t N> tag swap(T(&a)[N], T(&b)[N]);
|
|
|
|
// helper functions to test if an unqualified swap is possible, and if it
|
|
// becomes std::swap
|
|
template <class, class> std::false_type can_swap(...) noexcept(false);
|
|
template <class T, class U,
|
|
class = decltype(swap(std::declval<T&>(), std::declval<U&>()))>
|
|
std::true_type can_swap(int) noexcept(noexcept(swap(std::declval<T&>(),
|
|
std::declval<U&>())));
|
|
|
|
template <class, class> std::false_type uses_std(...);
|
|
template <class T, class U>
|
|
std::is_same<decltype(swap(std::declval<T&>(), std::declval<U&>())), tag>
|
|
uses_std(int);
|
|
|
|
template <class T>
|
|
struct is_std_swap_noexcept
|
|
: std::integral_constant<bool,
|
|
std::is_nothrow_move_constructible<T>::value&&
|
|
std::is_nothrow_move_assignable<T>::value> {};
|
|
|
|
template <class T, std::size_t N>
|
|
struct is_std_swap_noexcept<T[N]> : is_std_swap_noexcept<T> {};
|
|
|
|
template <class T, class U>
|
|
struct is_adl_swap_noexcept
|
|
: std::integral_constant<bool, noexcept(can_swap<T, U>(0))> {};
|
|
} // namespace swap_adl_tests
|
|
|
|
template <class T, class U = T>
|
|
struct is_swappable
|
|
: std::integral_constant<
|
|
bool,
|
|
decltype(detail::swap_adl_tests::can_swap<T, U>(0))::value &&
|
|
(!decltype(detail::swap_adl_tests::uses_std<T, U>(0))::value ||
|
|
(std::is_move_assignable<T>::value &&
|
|
std::is_move_constructible<T>::value))> {};
|
|
|
|
template <class T, std::size_t N>
|
|
struct is_swappable<T[N], T[N]>
|
|
: std::integral_constant<
|
|
bool,
|
|
decltype(detail::swap_adl_tests::can_swap<T[N], T[N]>(0))::value &&
|
|
(!decltype(
|
|
detail::swap_adl_tests::uses_std<T[N], T[N]>(0))::value ||
|
|
is_swappable<T, T>::value)> {};
|
|
|
|
template <class T, class U = T>
|
|
struct is_nothrow_swappable
|
|
: std::integral_constant<
|
|
bool,
|
|
is_swappable<T, U>::value &&
|
|
((decltype(detail::swap_adl_tests::uses_std<T, U>(0))::value
|
|
&& detail::swap_adl_tests::is_std_swap_noexcept<T>::value) ||
|
|
(!decltype(detail::swap_adl_tests::uses_std<T, U>(0))::value &&
|
|
detail::swap_adl_tests::is_adl_swap_noexcept<T,
|
|
U>::value))> {
|
|
};
|
|
#endif
|
|
#endif
|
|
|
|
// std::void_t from C++17
|
|
template <class...> struct voider { using type = void; };
|
|
template <class... Ts> using void_t = typename voider<Ts...>::type;
|
|
|
|
// Trait for checking if a type is a tl::optional
|
|
template <class T> struct is_optional_impl : std::false_type {};
|
|
template <class T> struct is_optional_impl<optional<T>> : std::true_type {};
|
|
template <class T> using is_optional = is_optional_impl<decay_t<T>>;
|
|
|
|
// Change void to tl::monostate
|
|
template <class U>
|
|
using fixup_void = conditional_t<std::is_void<U>::value, monostate, U>;
|
|
|
|
template <class F, class U, class = invoke_result_t<F, U>>
|
|
using get_map_return = optional<fixup_void<invoke_result_t<F, U>>>;
|
|
|
|
// Check if invoking F for some Us returns void
|
|
template <class F, class = void, class... U> struct returns_void_impl;
|
|
template <class F, class... U>
|
|
struct returns_void_impl<F, void_t<invoke_result_t<F, U...>>, U...>
|
|
: std::is_void<invoke_result_t<F, U...>> {};
|
|
template <class F, class... U>
|
|
using returns_void = returns_void_impl<F, void, U...>;
|
|
|
|
template <class T, class... U>
|
|
using enable_if_ret_void = enable_if_t<returns_void<T&&, U...>::value>;
|
|
|
|
template <class T, class... U>
|
|
using disable_if_ret_void = enable_if_t<!returns_void<T&&, U...>::value>;
|
|
|
|
template <class T, class U>
|
|
using 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<optional<T>, detail::decay_t<U>>::value>;
|
|
|
|
template <class T, class U, class Other>
|
|
using enable_from_other = detail::enable_if_t<
|
|
std::is_constructible<T, Other>::value &&
|
|
!std::is_constructible<T, optional<U>&>::value &&
|
|
!std::is_constructible<T, optional<U>&&>::value &&
|
|
!std::is_constructible<T, const optional<U>&>::value &&
|
|
!std::is_constructible<T, const optional<U>&&>::value &&
|
|
!std::is_convertible<optional<U>&, T>::value &&
|
|
!std::is_convertible<optional<U>&&, T>::value &&
|
|
!std::is_convertible<const optional<U>&, T>::value &&
|
|
!std::is_convertible<const optional<U>&&, T>::value>;
|
|
|
|
template <class T, class U>
|
|
using enable_assign_forward = detail::enable_if_t<
|
|
!std::is_same<optional<T>, 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<T&, U>::value>;
|
|
|
|
template <class T, class U, class Other>
|
|
using enable_assign_from_other = detail::enable_if_t<
|
|
std::is_constructible<T, Other>::value&&
|
|
std::is_assignable<T&, Other>::value &&
|
|
!std::is_constructible<T, optional<U>&>::value &&
|
|
!std::is_constructible<T, optional<U>&&>::value &&
|
|
!std::is_constructible<T, const optional<U>&>::value &&
|
|
!std::is_constructible<T, const optional<U>&&>::value &&
|
|
!std::is_convertible<optional<U>&, T>::value &&
|
|
!std::is_convertible<optional<U>&&, T>::value &&
|
|
!std::is_convertible<const optional<U>&, T>::value &&
|
|
!std::is_convertible<const optional<U>&&, T>::value &&
|
|
!std::is_assignable<T&, optional<U>&>::value &&
|
|
!std::is_assignable<T&, optional<U>&&>::value &&
|
|
!std::is_assignable<T&, const optional<U>&>::value &&
|
|
!std::is_assignable<T&, const optional<U>&&>::value>;
|
|
|
|
// The storage base manages the actual storage, and correctly propagates
|
|
// trivial destruction from T. This case is for when T is not trivially
|
|
// destructible.
|
|
template <class T, bool = ::std::is_trivially_destructible<T>::value>
|
|
struct optional_storage_base {
|
|
TL_OPTIONAL_11_CONSTEXPR optional_storage_base() noexcept
|
|
: m_dummy(), m_has_value(false) {}
|
|
|
|
template <class... U>
|
|
TL_OPTIONAL_11_CONSTEXPR optional_storage_base(in_place_t, U &&... u)
|
|
: m_value(std::forward<U>(u)...), m_has_value(true) {}
|
|
|
|
~optional_storage_base() {
|
|
if(m_has_value) {
|
|
m_value.~T();
|
|
m_has_value = false;
|
|
}
|
|
}
|
|
|
|
struct dummy {};
|
|
union {
|
|
dummy m_dummy;
|
|
T m_value;
|
|
};
|
|
|
|
bool m_has_value;
|
|
};
|
|
|
|
// This case is for when T is trivially destructible.
|
|
template <class T> struct optional_storage_base<T, true> {
|
|
TL_OPTIONAL_11_CONSTEXPR optional_storage_base() noexcept
|
|
: m_dummy(), m_has_value(false) {}
|
|
|
|
template <class... U>
|
|
TL_OPTIONAL_11_CONSTEXPR optional_storage_base(in_place_t, U &&... u)
|
|
: m_value(std::forward<U>(u)...), m_has_value(true) {}
|
|
|
|
// No destructor, so this class is trivially destructible
|
|
|
|
struct dummy {};
|
|
union {
|
|
dummy m_dummy;
|
|
T m_value;
|
|
};
|
|
|
|
bool m_has_value = false;
|
|
};
|
|
|
|
// This base class provides some handy member functions which can be used in
|
|
// further derived classes
|
|
template <class T> struct optional_operations_base : optional_storage_base<T> {
|
|
using optional_storage_base<T>::optional_storage_base;
|
|
|
|
void hard_reset() noexcept {
|
|
get().~T();
|
|
this->m_has_value = false;
|
|
}
|
|
|
|
template <class... Args> void construct(Args &&... args) noexcept {
|
|
new (std::addressof(this->m_value)) T(std::forward<Args>(args)...);
|
|
this->m_has_value = true;
|
|
}
|
|
|
|
template <class Opt> void assign(Opt&& rhs) {
|
|
if(this->has_value()) {
|
|
if(rhs.has_value()) {
|
|
this->m_value = std::forward<Opt>(rhs).get();
|
|
}
|
|
else {
|
|
this->m_value.~T();
|
|
this->m_has_value = false;
|
|
}
|
|
}
|
|
|
|
else if(rhs.has_value()) {
|
|
construct(std::forward<Opt>(rhs).get());
|
|
}
|
|
}
|
|
|
|
bool has_value() const { return this->m_has_value; }
|
|
|
|
TL_OPTIONAL_11_CONSTEXPR T& get()& { return this->m_value; }
|
|
TL_OPTIONAL_11_CONSTEXPR const T& get() const& { return this->m_value; }
|
|
TL_OPTIONAL_11_CONSTEXPR T&& get()&& { return std::move(this->m_value); }
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
constexpr const T&& get() const&& { return std::move(this->m_value); }
|
|
#endif
|
|
};
|
|
|
|
// This class manages conditionally having a trivial copy constructor
|
|
// This specialization is for when T is trivially copy constructible
|
|
template <class T, bool = TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T)>
|
|
struct optional_copy_base : optional_operations_base<T> {
|
|
using optional_operations_base<T>::optional_operations_base;
|
|
};
|
|
|
|
// This specialization is for when T is not trivially copy constructible
|
|
template <class T>
|
|
struct optional_copy_base<T, false> : optional_operations_base<T> {
|
|
using optional_operations_base<T>::optional_operations_base;
|
|
|
|
optional_copy_base() = default;
|
|
optional_copy_base(const optional_copy_base& rhs)
|
|
: optional_operations_base<T>() {
|
|
if(rhs.has_value()) {
|
|
this->construct(rhs.get());
|
|
}
|
|
else {
|
|
this->m_has_value = false;
|
|
}
|
|
}
|
|
|
|
optional_copy_base(optional_copy_base&& rhs) = default;
|
|
optional_copy_base& operator=(const optional_copy_base& rhs) = default;
|
|
optional_copy_base& operator=(optional_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_OPTIONAL_GCC49
|
|
template <class T, bool = std::is_trivially_move_constructible<T>::value>
|
|
struct optional_move_base : optional_copy_base<T> {
|
|
using optional_copy_base<T>::optional_copy_base;
|
|
};
|
|
#else
|
|
template <class T, bool = false> struct optional_move_base;
|
|
#endif
|
|
template <class T> struct optional_move_base<T, false> : optional_copy_base<T> {
|
|
using optional_copy_base<T>::optional_copy_base;
|
|
|
|
optional_move_base() = default;
|
|
optional_move_base(const optional_move_base& rhs) = default;
|
|
|
|
optional_move_base(optional_move_base&& rhs) noexcept(
|
|
std::is_nothrow_move_constructible<T>::value) {
|
|
if(rhs.has_value()) {
|
|
this->construct(std::move(rhs.get()));
|
|
}
|
|
else {
|
|
this->m_has_value = false;
|
|
}
|
|
}
|
|
optional_move_base& operator=(const optional_move_base& rhs) = default;
|
|
optional_move_base& operator=(optional_move_base&& rhs) = default;
|
|
};
|
|
|
|
// This class manages conditionally having a trivial copy assignment operator
|
|
template <class T, bool = TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) &&
|
|
TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) &&
|
|
TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T)>
|
|
struct optional_copy_assign_base : optional_move_base<T> {
|
|
using optional_move_base<T>::optional_move_base;
|
|
};
|
|
|
|
template <class T>
|
|
struct optional_copy_assign_base<T, false> : optional_move_base<T> {
|
|
using optional_move_base<T>::optional_move_base;
|
|
|
|
optional_copy_assign_base() = default;
|
|
optional_copy_assign_base(const optional_copy_assign_base& rhs) = default;
|
|
|
|
optional_copy_assign_base(optional_copy_assign_base&& rhs) = default;
|
|
optional_copy_assign_base& operator=(const optional_copy_assign_base& rhs) {
|
|
this->assign(rhs);
|
|
return *this;
|
|
}
|
|
optional_copy_assign_base&
|
|
operator=(optional_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_OPTIONAL_GCC49
|
|
template <class T, bool = std::is_trivially_destructible<T>::value
|
|
&& std::is_trivially_move_constructible<T>::value
|
|
&& std::is_trivially_move_assignable<T>::value>
|
|
struct optional_move_assign_base : optional_copy_assign_base<T> {
|
|
using optional_copy_assign_base<T>::optional_copy_assign_base;
|
|
};
|
|
#else
|
|
template <class T, bool = false> struct optional_move_assign_base;
|
|
#endif
|
|
|
|
template <class T>
|
|
struct optional_move_assign_base<T, false> : optional_copy_assign_base<T> {
|
|
using optional_copy_assign_base<T>::optional_copy_assign_base;
|
|
|
|
optional_move_assign_base() = default;
|
|
optional_move_assign_base(const optional_move_assign_base& rhs) = default;
|
|
|
|
optional_move_assign_base(optional_move_assign_base&& rhs) = default;
|
|
|
|
optional_move_assign_base&
|
|
operator=(const optional_move_assign_base& rhs) = default;
|
|
|
|
optional_move_assign_base&
|
|
operator=(optional_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;
|
|
}
|
|
};
|
|
|
|
// optional_delete_ctor_base will conditionally delete copy and move
|
|
// constructors depending on whether T is copy/move constructible
|
|
template <class T, bool EnableCopy = std::is_copy_constructible<T>::value,
|
|
bool EnableMove = std::is_move_constructible<T>::value>
|
|
struct optional_delete_ctor_base {
|
|
optional_delete_ctor_base() = default;
|
|
optional_delete_ctor_base(const optional_delete_ctor_base&) = default;
|
|
optional_delete_ctor_base(optional_delete_ctor_base&&) noexcept = default;
|
|
optional_delete_ctor_base&
|
|
operator=(const optional_delete_ctor_base&) = default;
|
|
optional_delete_ctor_base&
|
|
operator=(optional_delete_ctor_base&&) noexcept = default;
|
|
};
|
|
|
|
template <class T> struct optional_delete_ctor_base<T, true, false> {
|
|
optional_delete_ctor_base() = default;
|
|
optional_delete_ctor_base(const optional_delete_ctor_base&) = default;
|
|
optional_delete_ctor_base(optional_delete_ctor_base&&) noexcept = delete;
|
|
optional_delete_ctor_base&
|
|
operator=(const optional_delete_ctor_base&) = default;
|
|
optional_delete_ctor_base&
|
|
operator=(optional_delete_ctor_base&&) noexcept = default;
|
|
};
|
|
|
|
template <class T> struct optional_delete_ctor_base<T, false, true> {
|
|
optional_delete_ctor_base() = default;
|
|
optional_delete_ctor_base(const optional_delete_ctor_base&) = delete;
|
|
optional_delete_ctor_base(optional_delete_ctor_base&&) noexcept = default;
|
|
optional_delete_ctor_base&
|
|
operator=(const optional_delete_ctor_base&) = default;
|
|
optional_delete_ctor_base&
|
|
operator=(optional_delete_ctor_base&&) noexcept = default;
|
|
};
|
|
|
|
template <class T> struct optional_delete_ctor_base<T, false, false> {
|
|
optional_delete_ctor_base() = default;
|
|
optional_delete_ctor_base(const optional_delete_ctor_base&) = delete;
|
|
optional_delete_ctor_base(optional_delete_ctor_base&&) noexcept = delete;
|
|
optional_delete_ctor_base&
|
|
operator=(const optional_delete_ctor_base&) = default;
|
|
optional_delete_ctor_base&
|
|
operator=(optional_delete_ctor_base&&) noexcept = default;
|
|
};
|
|
|
|
// optional_delete_assign_base will conditionally delete copy and move
|
|
// constructors depending on whether T is copy/move constructible + assignable
|
|
template <class T,
|
|
bool EnableCopy = (std::is_copy_constructible<T>::value&&
|
|
std::is_copy_assignable<T>::value),
|
|
bool EnableMove = (std::is_move_constructible<T>::value&&
|
|
std::is_move_assignable<T>::value)>
|
|
struct optional_delete_assign_base {
|
|
optional_delete_assign_base() = default;
|
|
optional_delete_assign_base(const optional_delete_assign_base&) = default;
|
|
optional_delete_assign_base(optional_delete_assign_base&&) noexcept =
|
|
default;
|
|
optional_delete_assign_base&
|
|
operator=(const optional_delete_assign_base&) = default;
|
|
optional_delete_assign_base&
|
|
operator=(optional_delete_assign_base&&) noexcept = default;
|
|
};
|
|
|
|
template <class T> struct optional_delete_assign_base<T, true, false> {
|
|
optional_delete_assign_base() = default;
|
|
optional_delete_assign_base(const optional_delete_assign_base&) = default;
|
|
optional_delete_assign_base(optional_delete_assign_base&&) noexcept =
|
|
default;
|
|
optional_delete_assign_base&
|
|
operator=(const optional_delete_assign_base&) = default;
|
|
optional_delete_assign_base&
|
|
operator=(optional_delete_assign_base&&) noexcept = delete;
|
|
};
|
|
|
|
template <class T> struct optional_delete_assign_base<T, false, true> {
|
|
optional_delete_assign_base() = default;
|
|
optional_delete_assign_base(const optional_delete_assign_base&) = default;
|
|
optional_delete_assign_base(optional_delete_assign_base&&) noexcept =
|
|
default;
|
|
optional_delete_assign_base&
|
|
operator=(const optional_delete_assign_base&) = delete;
|
|
optional_delete_assign_base&
|
|
operator=(optional_delete_assign_base&&) noexcept = default;
|
|
};
|
|
|
|
template <class T> struct optional_delete_assign_base<T, false, false> {
|
|
optional_delete_assign_base() = default;
|
|
optional_delete_assign_base(const optional_delete_assign_base&) = default;
|
|
optional_delete_assign_base(optional_delete_assign_base&&) noexcept =
|
|
default;
|
|
optional_delete_assign_base&
|
|
operator=(const optional_delete_assign_base&) = delete;
|
|
optional_delete_assign_base&
|
|
operator=(optional_delete_assign_base&&) noexcept = delete;
|
|
};
|
|
|
|
} // namespace detail
|
|
|
|
/// A tag type to represent an empty optional
|
|
struct nullopt_t {
|
|
struct do_not_use {};
|
|
constexpr explicit nullopt_t(do_not_use, do_not_use) noexcept {}
|
|
};
|
|
/// Represents an empty optional
|
|
static constexpr nullopt_t nullopt{ nullopt_t::do_not_use{},
|
|
nullopt_t::do_not_use{} };
|
|
|
|
class bad_optional_access : public std::exception {
|
|
public:
|
|
bad_optional_access() = default;
|
|
const char* what() const noexcept { return "Optional has no value"; }
|
|
};
|
|
|
|
/// An optional object is an object that contains the storage for another
|
|
/// object and manages the lifetime of this contained object, if any. The
|
|
/// contained object may be initialized after the optional object has been
|
|
/// initialized, and may be destroyed before the optional object has been
|
|
/// destroyed. The initialization state of the contained object is tracked by
|
|
/// the optional object.
|
|
template <class T>
|
|
class optional : private detail::optional_move_assign_base<T>,
|
|
private detail::optional_delete_ctor_base<T>,
|
|
private detail::optional_delete_assign_base<T> {
|
|
using base = detail::optional_move_assign_base<T>;
|
|
|
|
static_assert(!std::is_same<T, in_place_t>::value,
|
|
"instantiation of optional with in_place_t is ill-formed");
|
|
static_assert(!std::is_same<detail::decay_t<T>, nullopt_t>::value,
|
|
"instantiation of optional with nullopt_t is ill-formed");
|
|
|
|
public:
|
|
// The different versions for C++14 and 11 are needed because deduced return
|
|
// types are not SFINAE-safe. This provides better support for things like
|
|
// generic lambdas. C.f.
|
|
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0826r0.html
|
|
#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) && \
|
|
!defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55)
|
|
/// Carries out some operation which returns an optional on the stored
|
|
/// object if there is one.
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto and_then(F&& f)& {
|
|
using result = detail::invoke_result_t<F, T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto and_then(F&& f)&& {
|
|
using result = detail::invoke_result_t<F, T&&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: result(nullopt);
|
|
}
|
|
|
|
template <class F> constexpr auto and_then(F&& f) const& {
|
|
using result = detail::invoke_result_t<F, const T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F> constexpr auto and_then(F&& f) const&& {
|
|
using result = detail::invoke_result_t<F, const T&&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: result(nullopt);
|
|
}
|
|
#endif
|
|
#else
|
|
/// Carries out some operation which returns an optional on the stored
|
|
/// object if there is one.
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t<F, T&> and_then(F&& f)& {
|
|
using result = detail::invoke_result_t<F, T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t<F, T&&> and_then(F&& f)&& {
|
|
using result = detail::invoke_result_t<F, T&&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: result(nullopt);
|
|
}
|
|
|
|
template <class F>
|
|
constexpr detail::invoke_result_t<F, const T&> and_then(F&& f) const& {
|
|
using result = detail::invoke_result_t<F, const T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F>
|
|
constexpr detail::invoke_result_t<F, const T&&> and_then(F&& f) const&& {
|
|
using result = detail::invoke_result_t<F, const T&&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: result(nullopt);
|
|
}
|
|
#endif
|
|
#endif
|
|
|
|
#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) && \
|
|
!defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55)
|
|
/// Carries out some operation on the stored object if there is one.
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto map(F&& f)& {
|
|
return optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto map(F&& f)&& {
|
|
return optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> constexpr auto map(F&& f) const& {
|
|
return optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> constexpr auto map(F&& f) const&& {
|
|
return optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
#else
|
|
/// Carries out some operation on the stored object if there is one.
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR decltype(optional_map_impl(std::declval<optional&>(),
|
|
std::declval<F&&>()))
|
|
map(F&& f)& {
|
|
return optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR decltype(optional_map_impl(std::declval<optional&&>(),
|
|
std::declval<F&&>()))
|
|
map(F&& f)&& {
|
|
return optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
|
|
template <class F>
|
|
constexpr decltype(optional_map_impl(std::declval<const optional&>(),
|
|
std::declval<F&&>()))
|
|
map(F&& f) const& {
|
|
return optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F>
|
|
constexpr decltype(optional_map_impl(std::declval<const optional&&>(),
|
|
std::declval<F&&>()))
|
|
map(F&& f) const&& {
|
|
return optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
#endif
|
|
#endif
|
|
|
|
#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) && \
|
|
!defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55)
|
|
/// Carries out some operation on the stored object if there is one.
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto transform(F&& f)& {
|
|
return optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto transform(F&& f)&& {
|
|
return optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> constexpr auto transform(F&& f) const& {
|
|
return optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> constexpr auto transform(F&& f) const&& {
|
|
return optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
#else
|
|
/// Carries out some operation on the stored object if there is one.
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR decltype(optional_map_impl(std::declval<optional&>(),
|
|
std::declval<F&&>()))
|
|
transform(F&& f)& {
|
|
return optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR decltype(optional_map_impl(std::declval<optional&&>(),
|
|
std::declval<F&&>()))
|
|
transform(F&& f)&& {
|
|
return optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
|
|
template <class F>
|
|
constexpr decltype(optional_map_impl(std::declval<const optional&>(),
|
|
std::declval<F&&>()))
|
|
transform(F&& f) const& {
|
|
return optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F>
|
|
constexpr decltype(optional_map_impl(std::declval<const optional&&>(),
|
|
std::declval<F&&>()))
|
|
transform(F&& f) const&& {
|
|
return optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
#endif
|
|
#endif
|
|
|
|
/// Calls `f` if the optional is empty
|
|
template <class F, detail::enable_if_ret_void<F>* = nullptr>
|
|
optional<T> TL_OPTIONAL_11_CONSTEXPR or_else(F&& f)& {
|
|
if(has_value())
|
|
return *this;
|
|
|
|
std::forward<F>(f)();
|
|
return nullopt;
|
|
}
|
|
|
|
template <class F, detail::disable_if_ret_void<F>* = nullptr>
|
|
optional<T> TL_OPTIONAL_11_CONSTEXPR or_else(F&& f)& {
|
|
return has_value() ? *this : std::forward<F>(f)();
|
|
}
|
|
|
|
template <class F, detail::enable_if_ret_void<F>* = nullptr>
|
|
optional<T> or_else(F&& f)&& {
|
|
if(has_value())
|
|
return std::move(*this);
|
|
|
|
std::forward<F>(f)();
|
|
return nullopt;
|
|
}
|
|
|
|
template <class F, detail::disable_if_ret_void<F>* = nullptr>
|
|
optional<T> TL_OPTIONAL_11_CONSTEXPR or_else(F&& f)&& {
|
|
return has_value() ? std::move(*this) : std::forward<F>(f)();
|
|
}
|
|
|
|
template <class F, detail::enable_if_ret_void<F>* = nullptr>
|
|
optional<T> or_else(F&& f) const& {
|
|
if(has_value())
|
|
return *this;
|
|
|
|
std::forward<F>(f)();
|
|
return nullopt;
|
|
}
|
|
|
|
template <class F, detail::disable_if_ret_void<F>* = nullptr>
|
|
optional<T> TL_OPTIONAL_11_CONSTEXPR or_else(F&& f) const& {
|
|
return has_value() ? *this : std::forward<F>(f)();
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F, detail::enable_if_ret_void<F>* = nullptr>
|
|
optional<T> or_else(F&& f) const&& {
|
|
if(has_value())
|
|
return std::move(*this);
|
|
|
|
std::forward<F>(f)();
|
|
return nullopt;
|
|
}
|
|
|
|
template <class F, detail::disable_if_ret_void<F>* = nullptr>
|
|
optional<T> or_else(F&& f) const&& {
|
|
return has_value() ? std::move(*this) : std::forward<F>(f)();
|
|
}
|
|
#endif
|
|
|
|
/// Maps the stored value with `f` if there is one, otherwise returns `u`.
|
|
template <class F, class U> U map_or(F&& f, U&& u)& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: std::forward<U>(u);
|
|
}
|
|
|
|
template <class F, class U> U map_or(F&& f, U&& u)&& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: std::forward<U>(u);
|
|
}
|
|
|
|
template <class F, class U> U map_or(F&& f, U&& u) const& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: std::forward<U>(u);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F, class U> U map_or(F&& f, U&& u) const&& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: std::forward<U>(u);
|
|
}
|
|
#endif
|
|
|
|
/// Maps the stored value with `f` if there is one, otherwise calls
|
|
/// `u` and returns the result.
|
|
template <class F, class U>
|
|
detail::invoke_result_t<U> map_or_else(F&& f, U&& u)& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: std::forward<U>(u)();
|
|
}
|
|
|
|
template <class F, class U>
|
|
detail::invoke_result_t<U> map_or_else(F&& f, U&& u)&& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: std::forward<U>(u)();
|
|
}
|
|
|
|
template <class F, class U>
|
|
detail::invoke_result_t<U> map_or_else(F&& f, U&& u) const& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: std::forward<U>(u)();
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F, class U>
|
|
detail::invoke_result_t<U> map_or_else(F&& f, U&& u) const&& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: std::forward<U>(u)();
|
|
}
|
|
#endif
|
|
|
|
/// Returns `u` if `*this` has a value, otherwise an empty optional.
|
|
template <class U>
|
|
constexpr optional<typename std::decay<U>::type> conjunction(U&& u) const {
|
|
using result = optional<detail::decay_t<U>>;
|
|
return has_value() ? result{ u } : result{ nullopt };
|
|
}
|
|
|
|
/// Returns `rhs` if `*this` is empty, otherwise the current value.
|
|
TL_OPTIONAL_11_CONSTEXPR optional disjunction(const optional& rhs)& {
|
|
return has_value() ? *this : rhs;
|
|
}
|
|
|
|
constexpr optional disjunction(const optional& rhs) const& {
|
|
return has_value() ? *this : rhs;
|
|
}
|
|
|
|
TL_OPTIONAL_11_CONSTEXPR optional disjunction(const optional& rhs)&& {
|
|
return has_value() ? std::move(*this) : rhs;
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
constexpr optional disjunction(const optional& rhs) const&& {
|
|
return has_value() ? std::move(*this) : rhs;
|
|
}
|
|
#endif
|
|
|
|
TL_OPTIONAL_11_CONSTEXPR optional disjunction(optional&& rhs)& {
|
|
return has_value() ? *this : std::move(rhs);
|
|
}
|
|
|
|
constexpr optional disjunction(optional&& rhs) const& {
|
|
return has_value() ? *this : std::move(rhs);
|
|
}
|
|
|
|
TL_OPTIONAL_11_CONSTEXPR optional disjunction(optional&& rhs)&& {
|
|
return has_value() ? std::move(*this) : std::move(rhs);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
constexpr optional disjunction(optional&& rhs) const&& {
|
|
return has_value() ? std::move(*this) : std::move(rhs);
|
|
}
|
|
#endif
|
|
|
|
/// Takes the value out of the optional, leaving it empty
|
|
optional take() {
|
|
optional ret = std::move(*this);
|
|
reset();
|
|
return ret;
|
|
}
|
|
|
|
using value_type = T;
|
|
|
|
/// Constructs an optional that does not contain a value.
|
|
constexpr optional() noexcept = default;
|
|
|
|
constexpr optional(nullopt_t) noexcept {}
|
|
|
|
/// Copy constructor
|
|
///
|
|
/// If `rhs` contains a value, the stored value is direct-initialized with
|
|
/// it. Otherwise, the constructed optional is empty.
|
|
TL_OPTIONAL_11_CONSTEXPR optional(const optional& rhs) = default;
|
|
|
|
/// Move constructor
|
|
///
|
|
/// If `rhs` contains a value, the stored value is direct-initialized with
|
|
/// it. Otherwise, the constructed optional is empty.
|
|
TL_OPTIONAL_11_CONSTEXPR optional(optional&& rhs) = default;
|
|
|
|
/// Constructs the stored value in-place using the given arguments.
|
|
template <class... Args>
|
|
constexpr explicit optional(
|
|
detail::enable_if_t<std::is_constructible<T, Args...>::value, in_place_t>,
|
|
Args &&... args)
|
|
: base(in_place, std::forward<Args>(args)...) {}
|
|
|
|
template <class U, class... Args>
|
|
TL_OPTIONAL_11_CONSTEXPR explicit optional(
|
|
detail::enable_if_t<std::is_constructible<T, std::initializer_list<U>&,
|
|
Args &&...>::value,
|
|
in_place_t>,
|
|
std::initializer_list<U> il, Args &&... args) {
|
|
this->construct(il, std::forward<Args>(args)...);
|
|
}
|
|
|
|
/// Constructs the stored value with `u`.
|
|
template <
|
|
class U = T,
|
|
detail::enable_if_t<std::is_convertible<U&&, T>::value>* = nullptr,
|
|
detail::enable_forward_value<T, U>* = nullptr>
|
|
constexpr optional(U&& u) : base(in_place, std::forward<U>(u)) {}
|
|
|
|
template <
|
|
class U = T,
|
|
detail::enable_if_t<!std::is_convertible<U&&, T>::value>* = nullptr,
|
|
detail::enable_forward_value<T, U>* = nullptr>
|
|
constexpr explicit optional(U&& u) : base(in_place, std::forward<U>(u)) {}
|
|
|
|
/// Converting copy constructor.
|
|
template <
|
|
class U, detail::enable_from_other<T, U, const U&>* = nullptr,
|
|
detail::enable_if_t<std::is_convertible<const U&, T>::value>* = nullptr>
|
|
optional(const optional<U>& rhs) {
|
|
if(rhs.has_value()) {
|
|
this->construct(*rhs);
|
|
}
|
|
}
|
|
|
|
template <class U, detail::enable_from_other<T, U, const U&>* = nullptr,
|
|
detail::enable_if_t<!std::is_convertible<const U&, T>::value>* =
|
|
nullptr>
|
|
explicit optional(const optional<U>& rhs) {
|
|
if(rhs.has_value()) {
|
|
this->construct(*rhs);
|
|
}
|
|
}
|
|
|
|
/// Converting move constructor.
|
|
template <
|
|
class U, detail::enable_from_other<T, U, U&&>* = nullptr,
|
|
detail::enable_if_t<std::is_convertible<U&&, T>::value>* = nullptr>
|
|
optional(optional<U>&& rhs) {
|
|
if(rhs.has_value()) {
|
|
this->construct(std::move(*rhs));
|
|
}
|
|
}
|
|
|
|
template <
|
|
class U, detail::enable_from_other<T, U, U&&>* = nullptr,
|
|
detail::enable_if_t<!std::is_convertible<U&&, T>::value>* = nullptr>
|
|
explicit optional(optional<U>&& rhs) {
|
|
if(rhs.has_value()) {
|
|
this->construct(std::move(*rhs));
|
|
}
|
|
}
|
|
|
|
/// Destroys the stored value if there is one.
|
|
~optional() = default;
|
|
|
|
/// Assignment to empty.
|
|
///
|
|
/// Destroys the current value if there is one.
|
|
optional& operator=(nullopt_t) noexcept {
|
|
if(has_value()) {
|
|
this->m_value.~T();
|
|
this->m_has_value = false;
|
|
}
|
|
|
|
return *this;
|
|
}
|
|
|
|
/// Copy assignment.
|
|
///
|
|
/// Copies the value from `rhs` if there is one. Otherwise resets the stored
|
|
/// value in `*this`.
|
|
optional& operator=(const optional& rhs) = default;
|
|
|
|
/// Move assignment.
|
|
///
|
|
/// Moves the value from `rhs` if there is one. Otherwise resets the stored
|
|
/// value in `*this`.
|
|
optional& operator=(optional&& rhs) = default;
|
|
|
|
/// Assigns the stored value from `u`, destroying the old value if there was
|
|
/// one.
|
|
template <class U = T, detail::enable_assign_forward<T, U>* = nullptr>
|
|
optional& operator=(U&& u) {
|
|
if(has_value()) {
|
|
this->m_value = std::forward<U>(u);
|
|
}
|
|
else {
|
|
this->construct(std::forward<U>(u));
|
|
}
|
|
|
|
return *this;
|
|
}
|
|
|
|
/// Converting copy assignment operator.
|
|
///
|
|
/// Copies the value from `rhs` if there is one. Otherwise resets the stored
|
|
/// value in `*this`.
|
|
template <class U,
|
|
detail::enable_assign_from_other<T, U, const U&>* = nullptr>
|
|
optional& operator=(const optional<U>& rhs) {
|
|
if(has_value()) {
|
|
if(rhs.has_value()) {
|
|
this->m_value = *rhs;
|
|
}
|
|
else {
|
|
this->hard_reset();
|
|
}
|
|
}
|
|
|
|
if(rhs.has_value()) {
|
|
this->construct(*rhs);
|
|
}
|
|
|
|
return *this;
|
|
}
|
|
|
|
// TODO check exception guarantee
|
|
/// Converting move assignment operator.
|
|
///
|
|
/// Moves the value from `rhs` if there is one. Otherwise resets the stored
|
|
/// value in `*this`.
|
|
template <class U, detail::enable_assign_from_other<T, U, U>* = nullptr>
|
|
optional& operator=(optional<U>&& rhs) {
|
|
if(has_value()) {
|
|
if(rhs.has_value()) {
|
|
this->m_value = std::move(*rhs);
|
|
}
|
|
else {
|
|
this->hard_reset();
|
|
}
|
|
}
|
|
|
|
if(rhs.has_value()) {
|
|
this->construct(std::move(*rhs));
|
|
}
|
|
|
|
return *this;
|
|
}
|
|
|
|
/// Constructs the value in-place, destroying the current one if there is
|
|
/// one.
|
|
template <class... Args> T& emplace(Args &&... args) {
|
|
static_assert(std::is_constructible<T, Args &&...>::value,
|
|
"T must be constructible with Args");
|
|
|
|
*this = nullopt;
|
|
this->construct(std::forward<Args>(args)...);
|
|
return value();
|
|
}
|
|
|
|
template <class U, class... Args>
|
|
detail::enable_if_t<
|
|
std::is_constructible<T, std::initializer_list<U>&, Args &&...>::value,
|
|
T&>
|
|
emplace(std::initializer_list<U> il, Args &&... args) {
|
|
*this = nullopt;
|
|
this->construct(il, std::forward<Args>(args)...);
|
|
return value();
|
|
}
|
|
|
|
/// Swaps this optional with the other.
|
|
///
|
|
/// If neither optionals have a value, nothing happens.
|
|
/// If both have a value, the values are swapped.
|
|
/// If one has a value, it is moved to the other and the movee is left
|
|
/// valueless.
|
|
void
|
|
swap(optional& rhs) noexcept(std::is_nothrow_move_constructible<T>::value
|
|
&& detail::is_nothrow_swappable<T>::value) {
|
|
using std::swap;
|
|
if(has_value()) {
|
|
if(rhs.has_value()) {
|
|
swap(**this, *rhs);
|
|
}
|
|
else {
|
|
new (std::addressof(rhs.m_value)) T(std::move(this->m_value));
|
|
this->m_value.T::~T();
|
|
}
|
|
}
|
|
else if(rhs.has_value()) {
|
|
new (std::addressof(this->m_value)) T(std::move(rhs.m_value));
|
|
rhs.m_value.T::~T();
|
|
}
|
|
swap(this->m_has_value, rhs.m_has_value);
|
|
}
|
|
|
|
/// Returns a pointer to the stored value
|
|
constexpr const T* operator->() const {
|
|
return std::addressof(this->m_value);
|
|
}
|
|
|
|
TL_OPTIONAL_11_CONSTEXPR T* operator->() {
|
|
return std::addressof(this->m_value);
|
|
}
|
|
|
|
/// Returns the stored value
|
|
TL_OPTIONAL_11_CONSTEXPR T& operator*()& { return this->m_value; }
|
|
|
|
constexpr const T& operator*() const& { return this->m_value; }
|
|
|
|
TL_OPTIONAL_11_CONSTEXPR T&& operator*()&& {
|
|
return std::move(this->m_value);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
constexpr const T&& operator*() const&& { return std::move(this->m_value); }
|
|
#endif
|
|
|
|
/// Returns whether or not the optional has a value
|
|
constexpr bool has_value() const noexcept { return this->m_has_value; }
|
|
|
|
constexpr explicit operator bool() const noexcept {
|
|
return this->m_has_value;
|
|
}
|
|
|
|
/// Returns the contained value if there is one, otherwise throws bad_optional_access
|
|
TL_OPTIONAL_11_CONSTEXPR T& value()& {
|
|
if(has_value())
|
|
return this->m_value;
|
|
throw bad_optional_access();
|
|
}
|
|
TL_OPTIONAL_11_CONSTEXPR const T& value() const& {
|
|
if(has_value())
|
|
return this->m_value;
|
|
throw bad_optional_access();
|
|
}
|
|
TL_OPTIONAL_11_CONSTEXPR T&& value()&& {
|
|
if(has_value())
|
|
return std::move(this->m_value);
|
|
throw bad_optional_access();
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
TL_OPTIONAL_11_CONSTEXPR const T&& value() const&& {
|
|
if(has_value())
|
|
return std::move(this->m_value);
|
|
throw bad_optional_access();
|
|
}
|
|
#endif
|
|
|
|
/// Returns the stored value if there is one, otherwise returns `u`
|
|
template <class U> constexpr T value_or(U&& u) const& {
|
|
static_assert(std::is_copy_constructible<T>::value &&
|
|
std::is_convertible<U&&, T>::value,
|
|
"T must be copy constructible and convertible from U");
|
|
return has_value() ? **this : static_cast<T>(std::forward<U>(u));
|
|
}
|
|
|
|
template <class U> TL_OPTIONAL_11_CONSTEXPR T value_or(U&& u)&& {
|
|
static_assert(std::is_move_constructible<T>::value &&
|
|
std::is_convertible<U&&, T>::value,
|
|
"T must be move constructible and convertible from U");
|
|
return has_value() ? **this : static_cast<T>(std::forward<U>(u));
|
|
}
|
|
|
|
/// Destroys the stored value if one exists, making the optional empty
|
|
void reset() noexcept {
|
|
if(has_value()) {
|
|
this->m_value.~T();
|
|
this->m_has_value = false;
|
|
}
|
|
}
|
|
}; // namespace tl
|
|
|
|
/// Compares two optional objects
|
|
template <class T, class U>
|
|
inline constexpr bool operator==(const optional<T>& lhs,
|
|
const optional<U>& rhs) {
|
|
return lhs.has_value() == rhs.has_value() &&
|
|
(!lhs.has_value() || *lhs == *rhs);
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator!=(const optional<T>& lhs,
|
|
const optional<U>& rhs) {
|
|
return lhs.has_value() != rhs.has_value() ||
|
|
(lhs.has_value() && *lhs != *rhs);
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator<(const optional<T>& lhs,
|
|
const optional<U>& rhs) {
|
|
return rhs.has_value() && (!lhs.has_value() || *lhs < *rhs);
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator>(const optional<T>& lhs,
|
|
const optional<U>& rhs) {
|
|
return lhs.has_value() && (!rhs.has_value() || *lhs > *rhs);
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator<=(const optional<T>& lhs,
|
|
const optional<U>& rhs) {
|
|
return !lhs.has_value() || (rhs.has_value() && *lhs <= *rhs);
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator>=(const optional<T>& lhs,
|
|
const optional<U>& rhs) {
|
|
return !rhs.has_value() || (lhs.has_value() && *lhs >= *rhs);
|
|
}
|
|
|
|
/// Compares an optional to a `nullopt`
|
|
template <class T>
|
|
inline constexpr bool operator==(const optional<T>& lhs, nullopt_t) noexcept {
|
|
return !lhs.has_value();
|
|
}
|
|
template <class T>
|
|
inline constexpr bool operator==(nullopt_t, const optional<T>& rhs) noexcept {
|
|
return !rhs.has_value();
|
|
}
|
|
template <class T>
|
|
inline constexpr bool operator!=(const optional<T>& lhs, nullopt_t) noexcept {
|
|
return lhs.has_value();
|
|
}
|
|
template <class T>
|
|
inline constexpr bool operator!=(nullopt_t, const optional<T>& rhs) noexcept {
|
|
return rhs.has_value();
|
|
}
|
|
template <class T>
|
|
inline constexpr bool operator<(const optional<T>&, nullopt_t) noexcept {
|
|
return false;
|
|
}
|
|
template <class T>
|
|
inline constexpr bool operator<(nullopt_t, const optional<T>& rhs) noexcept {
|
|
return rhs.has_value();
|
|
}
|
|
template <class T>
|
|
inline constexpr bool operator<=(const optional<T>& lhs, nullopt_t) noexcept {
|
|
return !lhs.has_value();
|
|
}
|
|
template <class T>
|
|
inline constexpr bool operator<=(nullopt_t, const optional<T>&) noexcept {
|
|
return true;
|
|
}
|
|
template <class T>
|
|
inline constexpr bool operator>(const optional<T>& lhs, nullopt_t) noexcept {
|
|
return lhs.has_value();
|
|
}
|
|
template <class T>
|
|
inline constexpr bool operator>(nullopt_t, const optional<T>&) noexcept {
|
|
return false;
|
|
}
|
|
template <class T>
|
|
inline constexpr bool operator>=(const optional<T>&, nullopt_t) noexcept {
|
|
return true;
|
|
}
|
|
template <class T>
|
|
inline constexpr bool operator>=(nullopt_t, const optional<T>& rhs) noexcept {
|
|
return !rhs.has_value();
|
|
}
|
|
|
|
/// Compares the optional with a value.
|
|
template <class T, class U>
|
|
inline constexpr bool operator==(const optional<T>& lhs, const U& rhs) {
|
|
return lhs.has_value() ? *lhs == rhs : false;
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator==(const U& lhs, const optional<T>& rhs) {
|
|
return rhs.has_value() ? lhs == *rhs : false;
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator!=(const optional<T>& lhs, const U& rhs) {
|
|
return lhs.has_value() ? *lhs != rhs : true;
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator!=(const U& lhs, const optional<T>& rhs) {
|
|
return rhs.has_value() ? lhs != *rhs : true;
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator<(const optional<T>& lhs, const U& rhs) {
|
|
return lhs.has_value() ? *lhs < rhs : true;
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator<(const U& lhs, const optional<T>& rhs) {
|
|
return rhs.has_value() ? lhs < *rhs : false;
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator<=(const optional<T>& lhs, const U& rhs) {
|
|
return lhs.has_value() ? *lhs <= rhs : true;
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator<=(const U& lhs, const optional<T>& rhs) {
|
|
return rhs.has_value() ? lhs <= *rhs : false;
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator>(const optional<T>& lhs, const U& rhs) {
|
|
return lhs.has_value() ? *lhs > rhs : false;
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator>(const U& lhs, const optional<T>& rhs) {
|
|
return rhs.has_value() ? lhs > *rhs : true;
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator>=(const optional<T>& lhs, const U& rhs) {
|
|
return lhs.has_value() ? *lhs >= rhs : false;
|
|
}
|
|
template <class T, class U>
|
|
inline constexpr bool operator>=(const U& lhs, const optional<T>& rhs) {
|
|
return rhs.has_value() ? lhs >= *rhs : true;
|
|
}
|
|
|
|
template <class T,
|
|
detail::enable_if_t<std::is_move_constructible<T>::value>* = nullptr,
|
|
detail::enable_if_t<detail::is_swappable<T>::value>* = nullptr>
|
|
void swap(optional<T>& lhs,
|
|
optional<T>& rhs) noexcept(noexcept(lhs.swap(rhs))) {
|
|
return lhs.swap(rhs);
|
|
}
|
|
|
|
namespace detail {
|
|
struct i_am_secret {};
|
|
} // namespace detail
|
|
|
|
template <class T = detail::i_am_secret, class U,
|
|
class Ret =
|
|
detail::conditional_t<std::is_same<T, detail::i_am_secret>::value,
|
|
detail::decay_t<U>, T>>
|
|
inline constexpr optional<Ret> make_optional(U&& v) {
|
|
return optional<Ret>(std::forward<U>(v));
|
|
}
|
|
|
|
template <class T, class... Args>
|
|
inline constexpr optional<T> make_optional(Args &&... args) {
|
|
return optional<T>(in_place, std::forward<Args>(args)...);
|
|
}
|
|
template <class T, class U, class... Args>
|
|
inline constexpr optional<T> make_optional(std::initializer_list<U> il,
|
|
Args &&... args) {
|
|
return optional<T>(in_place, il, std::forward<Args>(args)...);
|
|
}
|
|
|
|
#if __cplusplus >= 201703L
|
|
template <class T> optional(T)->optional<T>;
|
|
#endif
|
|
|
|
/// \exclude
|
|
namespace detail {
|
|
#ifdef TL_OPTIONAL_CXX14
|
|
template <class Opt, class F,
|
|
class Ret = decltype(detail::invoke(std::declval<F>(),
|
|
*std::declval<Opt>())),
|
|
detail::enable_if_t<!std::is_void<Ret>::value>* = nullptr>
|
|
constexpr auto optional_map_impl(Opt&& opt, F&& f) {
|
|
return opt.has_value()
|
|
? detail::invoke(std::forward<F>(f), *std::forward<Opt>(opt))
|
|
: optional<Ret>(nullopt);
|
|
}
|
|
|
|
template <class Opt, class F,
|
|
class Ret = decltype(detail::invoke(std::declval<F>(),
|
|
*std::declval<Opt>())),
|
|
detail::enable_if_t<std::is_void<Ret>::value>* = nullptr>
|
|
auto optional_map_impl(Opt&& opt, F&& f) {
|
|
if(opt.has_value()) {
|
|
detail::invoke(std::forward<F>(f), *std::forward<Opt>(opt));
|
|
return make_optional(monostate{});
|
|
}
|
|
|
|
return optional<monostate>(nullopt);
|
|
}
|
|
#else
|
|
template <class Opt, class F,
|
|
class Ret = decltype(detail::invoke(std::declval<F>(),
|
|
*std::declval<Opt>())),
|
|
detail::enable_if_t<!std::is_void<Ret>::value>* = nullptr>
|
|
|
|
constexpr auto optional_map_impl(Opt&& opt, F&& f) -> optional<Ret> {
|
|
return opt.has_value()
|
|
? detail::invoke(std::forward<F>(f), *std::forward<Opt>(opt))
|
|
: optional<Ret>(nullopt);
|
|
}
|
|
|
|
template <class Opt, class F,
|
|
class Ret = decltype(detail::invoke(std::declval<F>(),
|
|
*std::declval<Opt>())),
|
|
detail::enable_if_t<std::is_void<Ret>::value>* = nullptr>
|
|
|
|
auto optional_map_impl(Opt&& opt, F&& f) -> optional<monostate> {
|
|
if(opt.has_value()) {
|
|
detail::invoke(std::forward<F>(f), *std::forward<Opt>(opt));
|
|
return monostate{};
|
|
}
|
|
|
|
return nullopt;
|
|
}
|
|
#endif
|
|
} // namespace detail
|
|
|
|
/// Specialization for when `T` is a reference. `optional<T&>` acts similarly
|
|
/// to a `T*`, but provides more operations and shows intent more clearly.
|
|
template <class T> class optional<T&> {
|
|
public:
|
|
// The different versions for C++14 and 11 are needed because deduced return
|
|
// types are not SFINAE-safe. This provides better support for things like
|
|
// generic lambdas. C.f.
|
|
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0826r0.html
|
|
#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) && \
|
|
!defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55)
|
|
|
|
/// Carries out some operation which returns an optional on the stored
|
|
/// object if there is one.
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto and_then(F&& f)& {
|
|
using result = detail::invoke_result_t<F, T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto and_then(F&& f)&& {
|
|
using result = detail::invoke_result_t<F, T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
|
|
template <class F> constexpr auto and_then(F&& f) const& {
|
|
using result = detail::invoke_result_t<F, const T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F> constexpr auto and_then(F&& f) const&& {
|
|
using result = detail::invoke_result_t<F, const T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
#endif
|
|
#else
|
|
/// Carries out some operation which returns an optional on the stored
|
|
/// object if there is one.
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t<F, T&> and_then(F&& f)& {
|
|
using result = detail::invoke_result_t<F, T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t<F, T&> and_then(F&& f)&& {
|
|
using result = detail::invoke_result_t<F, T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
|
|
template <class F>
|
|
constexpr detail::invoke_result_t<F, const T&> and_then(F&& f) const& {
|
|
using result = detail::invoke_result_t<F, const T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F>
|
|
constexpr detail::invoke_result_t<F, const T&> and_then(F&& f) const&& {
|
|
using result = detail::invoke_result_t<F, const T&>;
|
|
static_assert(detail::is_optional<result>::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
#endif
|
|
#endif
|
|
|
|
#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) && \
|
|
!defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55)
|
|
/// Carries out some operation on the stored object if there is one.
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto map(F&& f)& {
|
|
return detail::optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto map(F&& f)&& {
|
|
return detail::optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> constexpr auto map(F&& f) const& {
|
|
return detail::optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> constexpr auto map(F&& f) const&& {
|
|
return detail::optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
#else
|
|
/// Carries out some operation on the stored object if there is one.
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR decltype(detail::optional_map_impl(std::declval<optional&>(),
|
|
std::declval<F&&>()))
|
|
map(F&& f)& {
|
|
return detail::optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR decltype(detail::optional_map_impl(std::declval<optional&&>(),
|
|
std::declval<F&&>()))
|
|
map(F&& f)&& {
|
|
return detail::optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
|
|
template <class F>
|
|
constexpr decltype(detail::optional_map_impl(std::declval<const optional&>(),
|
|
std::declval<F&&>()))
|
|
map(F&& f) const& {
|
|
return detail::optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F>
|
|
constexpr decltype(detail::optional_map_impl(std::declval<const optional&&>(),
|
|
std::declval<F&&>()))
|
|
map(F&& f) const&& {
|
|
return detail::optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
#endif
|
|
#endif
|
|
|
|
#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) && \
|
|
!defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55)
|
|
/// Carries out some operation on the stored object if there is one.
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto transform(F&& f)& {
|
|
return detail::optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> TL_OPTIONAL_11_CONSTEXPR auto transform(F&& f)&& {
|
|
return detail::optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> constexpr auto transform(F&& f) const& {
|
|
return detail::optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
template <class F> constexpr auto transform(F&& f) const&& {
|
|
return detail::optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
#else
|
|
/// Carries out some operation on the stored object if there is one.
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR decltype(detail::optional_map_impl(std::declval<optional&>(),
|
|
std::declval<F&&>()))
|
|
transform(F&& f)& {
|
|
return detail::optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
/// \group map
|
|
/// \synopsis template <class F> auto transform(F &&f) &&;
|
|
template <class F>
|
|
TL_OPTIONAL_11_CONSTEXPR decltype(detail::optional_map_impl(std::declval<optional&&>(),
|
|
std::declval<F&&>()))
|
|
transform(F&& f)&& {
|
|
return detail::optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
|
|
template <class F>
|
|
constexpr decltype(detail::optional_map_impl(std::declval<const optional&>(),
|
|
std::declval<F&&>()))
|
|
transform(F&& f) const& {
|
|
return detail::optional_map_impl(*this, std::forward<F>(f));
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F>
|
|
constexpr decltype(detail::optional_map_impl(std::declval<const optional&&>(),
|
|
std::declval<F&&>()))
|
|
transform(F&& f) const&& {
|
|
return detail::optional_map_impl(std::move(*this), std::forward<F>(f));
|
|
}
|
|
#endif
|
|
#endif
|
|
|
|
/// Calls `f` if the optional is empty
|
|
template <class F, detail::enable_if_ret_void<F>* = nullptr>
|
|
optional<T> TL_OPTIONAL_11_CONSTEXPR or_else(F&& f)& {
|
|
if(has_value())
|
|
return *this;
|
|
|
|
std::forward<F>(f)();
|
|
return nullopt;
|
|
}
|
|
|
|
template <class F, detail::disable_if_ret_void<F>* = nullptr>
|
|
optional<T> TL_OPTIONAL_11_CONSTEXPR or_else(F&& f)& {
|
|
return has_value() ? *this : std::forward<F>(f)();
|
|
}
|
|
|
|
template <class F, detail::enable_if_ret_void<F>* = nullptr>
|
|
optional<T> or_else(F&& f)&& {
|
|
if(has_value())
|
|
return std::move(*this);
|
|
|
|
std::forward<F>(f)();
|
|
return nullopt;
|
|
}
|
|
|
|
template <class F, detail::disable_if_ret_void<F>* = nullptr>
|
|
optional<T> TL_OPTIONAL_11_CONSTEXPR or_else(F&& f)&& {
|
|
return has_value() ? std::move(*this) : std::forward<F>(f)();
|
|
}
|
|
|
|
template <class F, detail::enable_if_ret_void<F>* = nullptr>
|
|
optional<T> or_else(F&& f) const& {
|
|
if(has_value())
|
|
return *this;
|
|
|
|
std::forward<F>(f)();
|
|
return nullopt;
|
|
}
|
|
|
|
template <class F, detail::disable_if_ret_void<F>* = nullptr>
|
|
optional<T> TL_OPTIONAL_11_CONSTEXPR or_else(F&& f) const& {
|
|
return has_value() ? *this : std::forward<F>(f)();
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F, detail::enable_if_ret_void<F>* = nullptr>
|
|
optional<T> or_else(F&& f) const&& {
|
|
if(has_value())
|
|
return std::move(*this);
|
|
|
|
std::forward<F>(f)();
|
|
return nullopt;
|
|
}
|
|
|
|
template <class F, detail::disable_if_ret_void<F>* = nullptr>
|
|
optional<T> or_else(F&& f) const&& {
|
|
return has_value() ? std::move(*this) : std::forward<F>(f)();
|
|
}
|
|
#endif
|
|
|
|
/// Maps the stored value with `f` if there is one, otherwise returns `u`
|
|
template <class F, class U> U map_or(F&& f, U&& u)& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: std::forward<U>(u);
|
|
}
|
|
|
|
template <class F, class U> U map_or(F&& f, U&& u)&& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: std::forward<U>(u);
|
|
}
|
|
|
|
template <class F, class U> U map_or(F&& f, U&& u) const& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: std::forward<U>(u);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F, class U> U map_or(F&& f, U&& u) const&& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: std::forward<U>(u);
|
|
}
|
|
#endif
|
|
|
|
/// Maps the stored value with `f` if there is one, otherwise calls
|
|
/// `u` and returns the result.
|
|
template <class F, class U>
|
|
detail::invoke_result_t<U> map_or_else(F&& f, U&& u)& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: std::forward<U>(u)();
|
|
}
|
|
|
|
template <class F, class U>
|
|
detail::invoke_result_t<U> map_or_else(F&& f, U&& u)&& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: std::forward<U>(u)();
|
|
}
|
|
|
|
template <class F, class U>
|
|
detail::invoke_result_t<U> map_or_else(F&& f, U&& u) const& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), **this)
|
|
: std::forward<U>(u)();
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
template <class F, class U>
|
|
detail::invoke_result_t<U> map_or_else(F&& f, U&& u) const&& {
|
|
return has_value() ? detail::invoke(std::forward<F>(f), std::move(**this))
|
|
: std::forward<U>(u)();
|
|
}
|
|
#endif
|
|
|
|
/// Returns `u` if `*this` has a value, otherwise an empty optional.
|
|
template <class U>
|
|
constexpr optional<typename std::decay<U>::type> conjunction(U&& u) const {
|
|
using result = optional<detail::decay_t<U>>;
|
|
return has_value() ? result{ u } : result{ nullopt };
|
|
}
|
|
|
|
/// Returns `rhs` if `*this` is empty, otherwise the current value.
|
|
TL_OPTIONAL_11_CONSTEXPR optional disjunction(const optional& rhs)& {
|
|
return has_value() ? *this : rhs;
|
|
}
|
|
|
|
constexpr optional disjunction(const optional& rhs) const& {
|
|
return has_value() ? *this : rhs;
|
|
}
|
|
|
|
TL_OPTIONAL_11_CONSTEXPR optional disjunction(const optional& rhs)&& {
|
|
return has_value() ? std::move(*this) : rhs;
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
constexpr optional disjunction(const optional& rhs) const&& {
|
|
return has_value() ? std::move(*this) : rhs;
|
|
}
|
|
#endif
|
|
|
|
TL_OPTIONAL_11_CONSTEXPR optional disjunction(optional&& rhs)& {
|
|
return has_value() ? *this : std::move(rhs);
|
|
}
|
|
|
|
constexpr optional disjunction(optional&& rhs) const& {
|
|
return has_value() ? *this : std::move(rhs);
|
|
}
|
|
|
|
TL_OPTIONAL_11_CONSTEXPR optional disjunction(optional&& rhs)&& {
|
|
return has_value() ? std::move(*this) : std::move(rhs);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
constexpr optional disjunction(optional&& rhs) const&& {
|
|
return has_value() ? std::move(*this) : std::move(rhs);
|
|
}
|
|
#endif
|
|
|
|
/// Takes the value out of the optional, leaving it empty
|
|
optional take() {
|
|
optional ret = std::move(*this);
|
|
reset();
|
|
return ret;
|
|
}
|
|
|
|
using value_type = T&;
|
|
|
|
/// Constructs an optional that does not contain a value.
|
|
constexpr optional() noexcept : m_value(nullptr) {}
|
|
|
|
constexpr optional(nullopt_t) noexcept : m_value(nullptr) {}
|
|
|
|
/// Copy constructor
|
|
///
|
|
/// If `rhs` contains a value, the stored value is direct-initialized with
|
|
/// it. Otherwise, the constructed optional is empty.
|
|
TL_OPTIONAL_11_CONSTEXPR optional(const optional& rhs) noexcept = default;
|
|
|
|
/// Move constructor
|
|
///
|
|
/// If `rhs` contains a value, the stored value is direct-initialized with
|
|
/// it. Otherwise, the constructed optional is empty.
|
|
TL_OPTIONAL_11_CONSTEXPR optional(optional&& rhs) = default;
|
|
|
|
/// Constructs the stored value with `u`.
|
|
template <class U = T,
|
|
detail::enable_if_t<!detail::is_optional<detail::decay_t<U>>::value>
|
|
* = nullptr>
|
|
constexpr optional(U&& u) noexcept : m_value(std::addressof(u)) {
|
|
static_assert(std::is_lvalue_reference<U>::value, "U must be an lvalue");
|
|
}
|
|
|
|
template <class U>
|
|
constexpr explicit optional(const optional<U>& rhs) noexcept : optional(*rhs) {}
|
|
|
|
/// No-op
|
|
~optional() = default;
|
|
|
|
/// Assignment to empty.
|
|
///
|
|
/// Destroys the current value if there is one.
|
|
optional& operator=(nullopt_t) noexcept {
|
|
m_value = nullptr;
|
|
return *this;
|
|
}
|
|
|
|
/// Copy assignment.
|
|
///
|
|
/// Rebinds this optional to the referee of `rhs` if there is one. Otherwise
|
|
/// resets the stored value in `*this`.
|
|
optional& operator=(const optional& rhs) = default;
|
|
|
|
/// Rebinds this optional to `u`.
|
|
template <class U = T,
|
|
detail::enable_if_t<!detail::is_optional<detail::decay_t<U>>::value>
|
|
* = nullptr>
|
|
optional& operator=(U&& u) {
|
|
static_assert(std::is_lvalue_reference<U>::value, "U must be an lvalue");
|
|
m_value = std::addressof(u);
|
|
return *this;
|
|
}
|
|
|
|
/// Converting copy assignment operator.
|
|
///
|
|
/// Rebinds this optional to the referee of `rhs` if there is one. Otherwise
|
|
/// resets the stored value in `*this`.
|
|
template <class U> optional& operator=(const optional<U>& rhs) noexcept {
|
|
m_value = std::addressof(rhs.value());
|
|
return *this;
|
|
}
|
|
|
|
/// Rebinds this optional to `u`.
|
|
template <class U = T,
|
|
detail::enable_if_t<!detail::is_optional<detail::decay_t<U>>::value>
|
|
* = nullptr>
|
|
optional& emplace(U&& u) noexcept {
|
|
return *this = std::forward<U>(u);
|
|
}
|
|
|
|
void swap(optional& rhs) noexcept { std::swap(m_value, rhs.m_value); }
|
|
|
|
/// Returns a pointer to the stored value
|
|
constexpr const T* operator->() const noexcept { return m_value; }
|
|
|
|
TL_OPTIONAL_11_CONSTEXPR T* operator->() noexcept { return m_value; }
|
|
|
|
/// Returns the stored value
|
|
TL_OPTIONAL_11_CONSTEXPR T& operator*() noexcept { return *m_value; }
|
|
|
|
constexpr const T& operator*() const noexcept { return *m_value; }
|
|
|
|
constexpr bool has_value() const noexcept { return m_value != nullptr; }
|
|
|
|
constexpr explicit operator bool() const noexcept {
|
|
return m_value != nullptr;
|
|
}
|
|
|
|
/// Returns the contained value if there is one, otherwise throws bad_optional_access
|
|
TL_OPTIONAL_11_CONSTEXPR T& value() {
|
|
if(has_value())
|
|
return *m_value;
|
|
throw bad_optional_access();
|
|
}
|
|
TL_OPTIONAL_11_CONSTEXPR const T& value() const {
|
|
if(has_value())
|
|
return *m_value;
|
|
throw bad_optional_access();
|
|
}
|
|
|
|
/// Returns the stored value if there is one, otherwise returns `u`
|
|
template <class U> constexpr T value_or(U&& u) const& noexcept {
|
|
static_assert(std::is_copy_constructible<T>::value &&
|
|
std::is_convertible<U&&, T>::value,
|
|
"T must be copy constructible and convertible from U");
|
|
return has_value() ? **this : static_cast<T>(std::forward<U>(u));
|
|
}
|
|
|
|
/// \group value_or
|
|
template <class U> TL_OPTIONAL_11_CONSTEXPR T value_or(U&& u) && noexcept {
|
|
static_assert(std::is_move_constructible<T>::value &&
|
|
std::is_convertible<U&&, T>::value,
|
|
"T must be move constructible and convertible from U");
|
|
return has_value() ? **this : static_cast<T>(std::forward<U>(u));
|
|
}
|
|
|
|
/// Destroys the stored value if one exists, making the optional empty
|
|
void reset() noexcept { m_value = nullptr; }
|
|
|
|
private:
|
|
T* m_value;
|
|
}; // namespace tl
|
|
|
|
|
|
|
|
} // namespace tl
|
|
|
|
namespace std {
|
|
// TODO SFINAE
|
|
template <class T> struct hash<tl::optional<T>> {
|
|
::std::size_t operator()(const tl::optional<T>& o) const {
|
|
if(!o.has_value())
|
|
return 0;
|
|
|
|
return std::hash<tl::detail::remove_const_t<T>>()(*o);
|
|
}
|
|
};
|
|
} // namespace std
|
|
|
|
#endif
|