From 90b00674dd75c245b9dd65534aaa2f6c7c3a0d1e Mon Sep 17 00:00:00 2001 From: Simon Brand Date: Wed, 6 Jun 2018 13:54:12 +0100 Subject: [PATCH] More C++14 void fixes --- tl/optional.hpp | 7 +- tl/optional.hpp.orig | 2298 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 2301 insertions(+), 4 deletions(-) create mode 100644 tl/optional.hpp.orig diff --git a/tl/optional.hpp b/tl/optional.hpp index 62015e4..75e28c3 100644 --- a/tl/optional.hpp +++ b/tl/optional.hpp @@ -1604,8 +1604,7 @@ template optional(T)->optional; /// \exclude namespace detail { -#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) && \ - !defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55) +#ifdef TL_OPTIONAL_CXX14 template (), *std::declval())), @@ -1623,10 +1622,10 @@ template (f), *std::forward(opt)); - return monostate{}; + return make_optional(monostate{}); } - return optional(nullopt); + return optional(nullopt); } #else template . +/// + +#ifndef TL_OPTIONAL_HPP +#define TL_OPTIONAL_HPP + +#define TL_OPTIONAL_VERSION_MAJOR 0 +#define TL_OPTIONAL_VERSION_MINOR 2 + +#include +#include +#include +#include +#include + +#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__ <= 4 && \ + !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::value +#define TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) std::has_trivial_copy_assign::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::value +#else +#define TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \ + std::is_trivially_copy_constructible::value +#define TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \ + std::is_trivially_copy_assignable::value +#define TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T) std::is_trivially_destructible::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)) +/// \exclude +#define TL_OPTIONAL_11_CONSTEXPR +#else +/// \exclude +#define TL_OPTIONAL_11_CONSTEXPR constexpr +#endif + +namespace tl { +#ifndef TL_MONOSTATE_INPLACE_MUTEX +#define TL_MONOSTATE_INPLACE_MUTEX +/// \brief Used to represent an optional with no data; essentially a bool +class monostate {}; + +/// \brief A tag type to tell optional to construct its value in-place +struct in_place_t { + explicit in_place_t() = default; +}; +/// \brief A tag to tell optional to construct its value in-place +static constexpr in_place_t in_place{}; +#endif + +template class optional; + +/// \exclude +namespace detail { +#ifndef TL_TRAITS_MUTEX +#define TL_TRAITS_MUTEX +// C++14-style aliases for brevity +template using remove_const_t = typename std::remove_const::type; +template +using remove_reference_t = typename std::remove_reference::type; +template using decay_t = typename std::decay::type; +template +using enable_if_t = typename std::enable_if::type; +template +using conditional_t = typename std::conditional::type; + +// std::conjunction from C++17 +template struct conjunction : std::true_type {}; +template struct conjunction : B {}; +template +struct conjunction + : std::conditional, B>::type {}; + +// std::invoke from C++17 +// https://stackoverflow.com/questions/38288042/c11-14-invoke-workaround +template >{}>, + int = 0> +constexpr auto invoke(Fn &&f, Args &&... args) noexcept( + noexcept(std::mem_fn(f)(std::forward(args)...))) + -> decltype(std::mem_fn(f)(std::forward(args)...)) { + return std::mem_fn(f)(std::forward(args)...); +} + +template >{}>> +constexpr auto invoke(Fn &&f, Args &&... args) noexcept( + noexcept(std::forward(f)(std::forward(args)...))) + -> decltype(std::forward(f)(std::forward(args)...)) { + return std::forward(f)(std::forward(args)...); +} + +// std::invoke_result from C++17 +template struct invoke_result_impl; + +template +struct invoke_result_impl< + F, decltype(detail::invoke(std::declval(), std::declval()...), void()), + Us...> { + using type = decltype(detail::invoke(std::declval(), std::declval()...)); +}; + +template +using invoke_result = invoke_result_impl; + +template +using invoke_result_t = typename invoke_result::type; +#endif + +// std::void_t from C++17 +template struct voider { using type = void; }; +template using void_t = typename voider::type; + +// Trait for checking if a type is a tl::optional +template struct is_optional_impl : std::false_type {}; +template struct is_optional_impl> : std::true_type {}; +template using is_optional = is_optional_impl>; + +// Change void to tl::monostate +template +using fixup_void = conditional_t::value, monostate, U>; + +template > +using get_map_return = optional>>; + +// Check if invoking F for some Us returns void +template struct returns_void_impl; +template +struct returns_void_impl>, U...> + : std::is_void> {}; +template +using returns_void = returns_void_impl; + +template +using enable_if_ret_void = enable_if_t::value>; + +template +using disable_if_ret_void = enable_if_t::value>; + +template +using enable_forward_value = + detail::enable_if_t::value && + !std::is_same, in_place_t>::value && + !std::is_same, detail::decay_t>::value>; + +template +using enable_from_other = detail::enable_if_t< + std::is_constructible::value && + !std::is_constructible &>::value && + !std::is_constructible &&>::value && + !std::is_constructible &>::value && + !std::is_constructible &&>::value && + !std::is_convertible &, T>::value && + !std::is_convertible &&, T>::value && + !std::is_convertible &, T>::value && + !std::is_convertible &&, T>::value>; + +template +using enable_assign_forward = detail::enable_if_t< + !std::is_same, detail::decay_t>::value && + !detail::conjunction, + std::is_same>>::value && + std::is_constructible::value && std::is_assignable::value>; + +template +using enable_assign_from_other = detail::enable_if_t< + std::is_constructible::value && + std::is_assignable::value && + !std::is_constructible &>::value && + !std::is_constructible &&>::value && + !std::is_constructible &>::value && + !std::is_constructible &&>::value && + !std::is_convertible &, T>::value && + !std::is_convertible &&, T>::value && + !std::is_convertible &, T>::value && + !std::is_convertible &&, T>::value && + !std::is_assignable &>::value && + !std::is_assignable &&>::value && + !std::is_assignable &>::value && + !std::is_assignable &&>::value>; + +#ifdef _MSC_VER +// TODO make a version which works with MSVC +template struct is_swappable : std::true_type {}; + +template 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 tag swap(T &, T &); +template 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 std::false_type can_swap(...) noexcept(false); +template (), std::declval()))> +std::true_type can_swap(int) noexcept(noexcept(swap(std::declval(), + std::declval()))); + +template std::false_type uses_std(...); +template +std::is_same(), std::declval())), tag> +uses_std(int); + +template +struct is_std_swap_noexcept + : std::integral_constant::value && + std::is_nothrow_move_assignable::value> {}; + +template +struct is_std_swap_noexcept : is_std_swap_noexcept {}; + +template +struct is_adl_swap_noexcept + : std::integral_constant(0))> {}; +} // namespace swap_adl_tests + +template +struct is_swappable + : std::integral_constant< + bool, + decltype(detail::swap_adl_tests::can_swap(0))::value && + (!decltype(detail::swap_adl_tests::uses_std(0))::value || + (std::is_move_assignable::value && + std::is_move_constructible::value))> {}; + +template +struct is_swappable + : std::integral_constant< + bool, + decltype(detail::swap_adl_tests::can_swap(0))::value && + (!decltype( + detail::swap_adl_tests::uses_std(0))::value || + is_swappable::value)> {}; + +template +struct is_nothrow_swappable + : std::integral_constant< + bool, + is_swappable::value && + ((decltype(detail::swap_adl_tests::uses_std(0))::value + &&detail::swap_adl_tests::is_std_swap_noexcept::value) || + (!decltype(detail::swap_adl_tests::uses_std(0))::value && + detail::swap_adl_tests::is_adl_swap_noexcept::value))> { +}; +#endif + +// The storage base manages the actual storage, and correctly propagates +// trivial destruction from T This case is for when T is trivially +// destructible +template ::value> +struct optional_storage_base { + TL_OPTIONAL_11_CONSTEXPR optional_storage_base() noexcept + : m_dummy(), m_has_value(false) {} + + template + TL_OPTIONAL_11_CONSTEXPR optional_storage_base(in_place_t, U &&... u) + : m_value(std::forward(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 not trivially destructible +template struct optional_storage_base { + TL_OPTIONAL_11_CONSTEXPR optional_storage_base() noexcept + : m_dummy(), m_has_value(false) {} + + template + TL_OPTIONAL_11_CONSTEXPR optional_storage_base(in_place_t, U &&... u) + : m_value(std::forward(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 struct optional_operations_base : optional_storage_base { + using optional_storage_base::optional_storage_base; + + void hard_reset() noexcept { + get().~T(); + this->m_has_value = false; + } + + template void construct(Args &&... args) noexcept { + new (std::addressof(this->m_value)) T(std::forward(args)...); + this->m_has_value = true; + } + + template void assign(Opt &&rhs) { + if (this->has_value()) { + if (rhs.has_value()) { + this->m_value = std::forward(rhs).get(); + } else { + this->m_value.~T(); + this->m_has_value = false; + } + } + + if (rhs.has_value()) { + construct(std::forward(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 +struct optional_copy_base : optional_operations_base { + using optional_operations_base::optional_operations_base; +}; + +// This specialization is for when T is not trivially copy constructible +template +struct optional_copy_base : optional_operations_base { + using optional_operations_base::optional_operations_base; + + optional_copy_base() = default; + optional_copy_base(const optional_copy_base &rhs) { + 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 ::value> +struct optional_move_base : optional_copy_base { + using optional_copy_base::optional_copy_base; +}; +#else +template struct optional_move_base; +#endif +template struct optional_move_base : optional_copy_base { + using optional_copy_base::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::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 +struct optional_copy_assign_base : optional_move_base { + using optional_move_base::optional_move_base; +}; + +template +struct optional_copy_assign_base : optional_move_base { + using optional_move_base::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 ::value + &&std::is_trivially_move_constructible::value + &&std::is_trivially_move_assignable::value> +struct optional_move_assign_base : optional_copy_assign_base { + using optional_copy_assign_base::optional_copy_assign_base; +}; +#else +template struct optional_move_assign_base; +#endif + +template +struct optional_move_assign_base : optional_copy_assign_base { + using optional_copy_assign_base::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::value + &&std::is_nothrow_move_assignable::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 ::value, + bool EnableMove = std::is_move_constructible::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 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 = delete; + optional_delete_ctor_base & + operator=(const optional_delete_ctor_base &) = default; + optional_delete_ctor_base & + operator=(optional_delete_ctor_base &&) noexcept = default; +}; + +template struct optional_delete_ctor_base { + 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 struct optional_delete_ctor_base { + 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 ::value && + std::is_copy_assignable::value), + bool EnableMove = (std::is_move_constructible::value && + std::is_move_assignable::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 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 = delete; +}; + +template 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 &) = delete; + optional_delete_assign_base & + operator=(optional_delete_assign_base &&) noexcept = default; +}; + +template 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 &) = delete; + optional_delete_assign_base & + operator=(optional_delete_assign_base &&) noexcept = delete; +}; + +} // namespace detail + +/// \brief 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 {} +}; +/// \brief Represents an empty optional +/// \synopsis static constexpr nullopt_t nullopt; +/// +/// *Examples*: +/// ``` +/// tl::optional a = tl::nullopt; +/// void foo (tl::optional); +/// foo(tl::nullopt); //pass 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 optional : private detail::optional_move_assign_base, + private detail::optional_delete_ctor_base, + private detail::optional_delete_assign_base { + using base = detail::optional_move_assign_base; + + static_assert(!std::is_same::value, + "instantiation of optional with in_place_t is ill-formed"); + static_assert(!std::is_same, 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) + /// \group and_then + /// Carries out some operation which returns an optional on the stored + /// object if there is one. \requires `std::invoke(std::forward(f), + /// value())` returns a `std::optional` for some `U`. \returns Let `U` be + /// the result of `std::invoke(std::forward(f), value())`. Returns a + /// `std::optional`. The return value is empty if `*this` is empty, + /// otherwise the return value of `std::invoke(std::forward(f), value())` + /// is returned. + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) &; + template TL_OPTIONAL_11_CONSTEXPR auto and_then(F &&f) & { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } + + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) &&; + template TL_OPTIONAL_11_CONSTEXPR auto and_then(F &&f) && { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), std::move(**this)) + : result(nullopt); + } + + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) const &; + template constexpr auto and_then(F &&f) const & { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) const &&; + template constexpr auto and_then(F &&f) const && { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), std::move(**this)) + : result(nullopt); + } +#endif +#else + /// \group and_then + /// Carries out some operation which returns an optional on the stored + /// object if there is one. \requires `std::invoke(std::forward(f), + /// value())` returns a `std::optional` for some `U`. + /// \returns Let `U` be the result of `std::invoke(std::forward(f), + /// value())`. Returns a `std::optional`. The return value is empty if + /// `*this` is empty, otherwise the return value of + /// `std::invoke(std::forward(f), value())` is returned. + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) &; + template + TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t and_then(F &&f) & { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } + + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) &&; + template + TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t and_then(F &&f) && { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), std::move(**this)) + : result(nullopt); + } + + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) const &; + template + constexpr detail::invoke_result_t and_then(F &&f) const & { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) const &&; + template + constexpr detail::invoke_result_t and_then(F &&f) const && { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(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) + /// \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), + /// value())`. Returns a `std::optional`. The return value is empty if + /// `*this` is empty, otherwise an `optional` is constructed from the + /// return value of `std::invoke(std::forward(f), value())` and is + /// returned. + /// + /// \group map + /// \synopsis template constexpr auto map(F &&f) &; + template TL_OPTIONAL_11_CONSTEXPR auto map(F &&f) & { + return optional_map_impl(*this, std::forward(f)); + } + + /// \group map + /// \synopsis template constexpr auto map(F &&f) &&; + template TL_OPTIONAL_11_CONSTEXPR auto map(F &&f) && { + return optional_map_impl(std::move(*this), std::forward(f)); + } + + /// \group map + /// \synopsis template constexpr auto map(F &&f) const&; + template constexpr auto map(F &&f) const & { + return optional_map_impl(*this, std::forward(f)); + } + + /// \group map + /// \synopsis template constexpr auto map(F &&f) const&&; + template constexpr auto map(F &&f) const && { + return optional_map_impl(std::move(*this), std::forward(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), + /// value())`. Returns a `std::optional`. The return value is empty if + /// `*this` is empty, otherwise an `optional` is constructed from the + /// return value of `std::invoke(std::forward(f), value())` and is + /// returned. + /// + /// \group map + /// \synopsis template auto map(F &&f) &; + template + TL_OPTIONAL_11_CONSTEXPR decltype(optional_map_impl(std::declval(), + std::declval())) + map(F &&f) & { + return optional_map_impl(*this, std::forward(f)); + } + + /// \group map + /// \synopsis template auto map(F &&f) &&; + template + TL_OPTIONAL_11_CONSTEXPR decltype(optional_map_impl(std::declval(), + std::declval())) + map(F &&f) && { + return optional_map_impl(std::move(*this), std::forward(f)); + } + + /// \group map + /// \synopsis template auto map(F &&f) const&; + template + constexpr decltype(optional_map_impl(std::declval(), + std::declval())) + map(F &&f) const & { + return optional_map_impl(*this, std::forward(f)); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group map + /// \synopsis template auto map(F &&f) const&&; + template + constexpr decltype(optional_map_impl(std::declval(), + std::declval())) + map(F &&f) const && { + return optional_map_impl(std::move(*this), std::forward(f)); + } +#endif +#endif + + /// \brief Calls `f` if the optional is empty + /// \requires `std::invoke_result_t` must be void or convertible to + /// `optional`. + /// \effects If `*this` has a value, returns `*this`. + /// Otherwise, if `f` returns `void`, calls `std::forward(f)` and returns + /// `std::nullopt`. Otherwise, returns `std::forward(f)()`. + /// + /// \group or_else + /// \synopsis template optional or_else (F &&f) &; + template * = nullptr> + optional TL_OPTIONAL_11_CONSTEXPR or_else(F &&f) & { + if (has_value()) + return *this; + + std::forward(f)(); + return nullopt; + } + + /// \exclude + template * = nullptr> + optional TL_OPTIONAL_11_CONSTEXPR or_else(F &&f) & { + return has_value() ? *this : std::forward(f)(); + } + + /// \group or_else + /// \synopsis template optional or_else (F &&f) &&; + template * = nullptr> + optional or_else(F &&f) && { + if (has_value()) + return std::move(*this); + + std::forward(f)(); + return nullopt; + } + + /// \exclude + template * = nullptr> + optional TL_OPTIONAL_11_CONSTEXPR or_else(F &&f) && { + return has_value() ? std::move(*this) : std::forward(f)(); + } + + /// \group or_else + /// \synopsis template optional or_else (F &&f) const &; + template * = nullptr> + optional or_else(F &&f) const & { + if (has_value()) + return *this; + + std::forward(f)(); + return nullopt; + } + + /// \exclude + template * = nullptr> + optional TL_OPTIONAL_11_CONSTEXPR or_else(F &&f) const & { + return has_value() ? *this : std::forward(f)(); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \exclude + template * = nullptr> + optional or_else(F &&f) const && { + if (has_value()) + return std::move(*this); + + std::forward(f)(); + return nullopt; + } + + /// \exclude + template * = nullptr> + optional or_else(F &&f) const && { + return has_value() ? std::move(*this) : std::forward(f)(); + } +#endif + + /// \brief Maps the stored value with `f` if there is one, otherwise returns + /// `u`. + /// + /// \details If there is a value stored, then `f` is called with `**this` + /// and the value is returned. Otherwise `u` is returned. + /// + /// \group map_or + template U map_or(F &&f, U &&u) & { + return has_value() ? detail::invoke(std::forward(f), **this) + : std::forward(u); + } + + /// \group map_or + template U map_or(F &&f, U &&u) && { + return has_value() ? detail::invoke(std::forward(f), std::move(**this)) + : std::forward(u); + } + + /// \group map_or + template U map_or(F &&f, U &&u) const & { + return has_value() ? detail::invoke(std::forward(f), **this) + : std::forward(u); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group map_or + template U map_or(F &&f, U &&u) const && { + return has_value() ? detail::invoke(std::forward(f), std::move(**this)) + : std::forward(u); + } +#endif + + /// \brief Maps the stored value with `f` if there is one, otherwise calls + /// `u` and returns the result. + /// + /// \details If there is a value stored, then `f` is + /// called with `**this` and the value is returned. Otherwise + /// `std::forward(u)()` is returned. + /// + /// \group map_or_else + /// \synopsis template \nauto map_or_else(F &&f, U &&u) &; + template + detail::invoke_result_t map_or_else(F &&f, U &&u) & { + return has_value() ? detail::invoke(std::forward(f), **this) + : std::forward(u)(); + } + + /// \group map_or_else + /// \synopsis template \nauto map_or_else(F &&f, U &&u) + /// &&; + template + detail::invoke_result_t map_or_else(F &&f, U &&u) && { + return has_value() ? detail::invoke(std::forward(f), std::move(**this)) + : std::forward(u)(); + } + + /// \group map_or_else + /// \synopsis template \nauto map_or_else(F &&f, U &&u) + /// const &; + template + detail::invoke_result_t map_or_else(F &&f, U &&u) const & { + return has_value() ? detail::invoke(std::forward(f), **this) + : std::forward(u)(); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group map_or_else + /// \synopsis template \nauto map_or_else(F &&f, U &&u) + /// const &&; + template + detail::invoke_result_t map_or_else(F &&f, U &&u) const && { + return has_value() ? detail::invoke(std::forward(f), std::move(**this)) + : std::forward(u)(); + } +#endif + + /// \returns `u` if `*this` has a value, otherwise an empty optional. + template + constexpr optional::type> conjunction(U &&u) const { + using result = optional>; + return has_value() ? result{u} : result{nullopt}; + } + + /// \returns `rhs` if `*this` is empty, otherwise the current value. + /// \group disjunction + TL_OPTIONAL_11_CONSTEXPR optional disjunction(const optional &rhs) & { + return has_value() ? *this : rhs; + } + + /// \group disjunction + constexpr optional disjunction(const optional &rhs) const & { + return has_value() ? *this : rhs; + } + + /// \group disjunction + TL_OPTIONAL_11_CONSTEXPR optional disjunction(const optional &rhs) && { + return has_value() ? std::move(*this) : rhs; + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group disjunction + constexpr optional disjunction(const optional &rhs) const && { + return has_value() ? std::move(*this) : rhs; + } +#endif + + /// \group disjunction + TL_OPTIONAL_11_CONSTEXPR optional disjunction(optional &&rhs) & { + return has_value() ? *this : std::move(rhs); + } + + /// \group disjunction + constexpr optional disjunction(optional &&rhs) const & { + return has_value() ? *this : std::move(rhs); + } + + /// \group disjunction + TL_OPTIONAL_11_CONSTEXPR optional disjunction(optional &&rhs) && { + return has_value() ? std::move(*this) : std::move(rhs); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group disjunction + 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 + /// \group take + optional take() & { + optional ret = *this; + reset(); + return ret; + } + + /// \group take + optional take() const & { + optional ret = *this; + reset(); + return ret; + } + + /// \group take + optional take() && { + optional ret = std::move(*this); + reset(); + return ret; + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group take + optional take() const && { + optional ret = std::move(*this); + reset(); + return ret; + } +#endif + + using value_type = T; + + /// Constructs an optional that does not contain a value. + /// \group ctor_empty + constexpr optional() noexcept = default; + + /// \group ctor_empty + 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. + /// \group in_place + /// \synopsis template constexpr explicit optional(in_place_t, Args&&... args); + template + constexpr explicit optional( + detail::enable_if_t::value, in_place_t>, + Args &&... args) + : base(in_place, std::forward(args)...) {} + + /// \group in_place + /// \synopsis template \nconstexpr explicit optional(in_place_t, std::initializer_list&, Args&&... args); + template + TL_OPTIONAL_11_CONSTEXPR explicit optional( + detail::enable_if_t &, + Args &&...>::value, + in_place_t>, + std::initializer_list il, Args &&... args) { + this->construct(il, std::forward(args)...); + } + + /// Constructs the stored value with `u`. + /// \synopsis template constexpr optional(U &&u); + template < + class U = T, + detail::enable_if_t::value> * = nullptr, + detail::enable_forward_value * = nullptr> + constexpr optional(U &&u) : base(in_place, std::forward(u)) {} + + /// \exclude + template < + class U = T, + detail::enable_if_t::value> * = nullptr, + detail::enable_forward_value * = nullptr> + constexpr explicit optional(U &&u) : base(in_place, std::forward(u)) {} + + /// Converting copy constructor. + /// \synopsis template optional(const optional &rhs); + template < + class U, detail::enable_from_other * = nullptr, + detail::enable_if_t::value> * = nullptr> + optional(const optional &rhs) { + this->construct(*rhs); + } + + /// \exclude + template * = nullptr, + detail::enable_if_t::value> * = + nullptr> + explicit optional(const optional &rhs) { + this->construct(*rhs); + } + + /// Converting move constructor. + /// \synopsis template optional(optional &&rhs); + template < + class U, detail::enable_from_other * = nullptr, + detail::enable_if_t::value> * = nullptr> + optional(optional &&rhs) { + this->construct(std::move(*rhs)); + } + + /// \exclude + template < + class U, detail::enable_from_other * = nullptr, + detail::enable_if_t::value> * = nullptr> + explicit optional(optional &&rhs) { + 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. + /// \synopsis optional &operator=(U &&u); + template * = nullptr> + optional &operator=(U &&u) { + if (has_value()) { + this->m_value = std::forward(u); + } else { + this->construct(std::forward(u)); + } + + return *this; + } + + /// Converting copy assignment operator. + /// + /// Copies the value from `rhs` if there is one. Otherwise resets the stored + /// value in `*this`. + /// \synopsis optional &operator=(const optional & rhs); + template * = nullptr> + optional &operator=(const optional &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`. + /// \synopsis optional &operator=(optional && rhs); + template * = nullptr> + optional &operator=(optional &&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. + /// \group emplace + template T &emplace(Args &&... args) { + static_assert(std::is_constructible::value, + "T must be constructible with Args"); + + *this = nullopt; + this->construct(std::forward(args)...); + } + + /// \group emplace + /// \synopsis template \nT& emplace(std::initializer_list il, Args &&... args); + template + detail::enable_if_t< + std::is_constructible &, Args &&...>::value, + T &> + emplace(std::initializer_list il, Args &&... args) { + *this = nullopt; + this->construct(il, std::forward(args)...); + } + + /// 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::value + &&detail::is_nothrow_swappable::value) { + if (has_value()) { + if (rhs.has_value()) { + using std::swap; + 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(); + } + } + + /// \returns a pointer to the stored value + /// \requires a value is stored + /// \group pointer + /// \synopsis constexpr const T *operator->() const; + constexpr const T *operator->() const { + return std::addressof(this->m_value); + } + + /// \group pointer + /// \synopsis constexpr T *operator->(); + TL_OPTIONAL_11_CONSTEXPR T *operator->() { + return std::addressof(this->m_value); + } + + /// \returns the stored value + /// \requires a value is stored + /// \group deref + /// \synopsis constexpr T &operator*(); + TL_OPTIONAL_11_CONSTEXPR T &operator*() & { return this->m_value; } + + /// \group deref + /// \synopsis constexpr const T &operator*() const; + constexpr const T &operator*() const & { return this->m_value; } + + /// \exclude + TL_OPTIONAL_11_CONSTEXPR T &&operator*() && { + return std::move(this->m_value); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \exclude + constexpr const T &&operator*() const && { return std::move(this->m_value); } +#endif + + /// \returns whether or not the optional has a value + /// \group has_value + constexpr bool has_value() const noexcept { return this->m_has_value; } + + /// \group 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] + /// \group value + /// \synopsis constexpr T &value(); + TL_OPTIONAL_11_CONSTEXPR T &value() & { + if (has_value()) + return this->m_value; + throw bad_optional_access(); + } + /// \group value + /// \synopsis constexpr const T &value() const; + TL_OPTIONAL_11_CONSTEXPR const T &value() const & { + if (has_value()) + return this->m_value; + throw bad_optional_access(); + } + /// \exclude + TL_OPTIONAL_11_CONSTEXPR T &&value() && { + if (has_value()) + return std::move(this->m_value); + throw bad_optional_access(); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \exclude + 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` + /// \group value_or + template constexpr T value_or(U &&u) const & { + static_assert(std::is_copy_constructible::value && + std::is_convertible::value, + "T must be copy constructible and convertible from U"); + return has_value() ? **this : static_cast(std::forward(u)); + } + + /// \group value_or + template TL_OPTIONAL_11_CONSTEXPR T value_or(U &&u) && { + static_assert(std::is_move_constructible::value && + std::is_convertible::value, + "T must be move constructible and convertible from U"); + return has_value() ? **this : static_cast(std::forward(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 + +/// \group relop +/// \brief Compares two optional objects +/// \details If both optionals contain a value, they are compared with `T`s +/// relational operators. Otherwise `lhs` and `rhs` are equal only if they are +/// both empty, and `lhs` is less than `rhs` only if `rhs` is empty and `lhs` +/// is not. +template +inline constexpr bool operator==(const optional &lhs, + const optional &rhs) { + return lhs.has_value() == rhs.has_value() && + (!lhs.has_value() || *lhs == *rhs); +} +/// \group relop +template +inline constexpr bool operator!=(const optional &lhs, + const optional &rhs) { + return lhs.has_value() != rhs.has_value() || + (lhs.has_value() && *lhs != *rhs); +} +/// \group relop +template +inline constexpr bool operator<(const optional &lhs, + const optional &rhs) { + return rhs.has_value() && (!lhs.has_value() || *lhs < *rhs); +} +/// \group relop +template +inline constexpr bool operator>(const optional &lhs, + const optional &rhs) { + return lhs.has_value() && (!rhs.has_value() || *lhs > *rhs); +} +/// \group relop +template +inline constexpr bool operator<=(const optional &lhs, + const optional &rhs) { + return !lhs.has_value() || (rhs.has_value() && *lhs <= *rhs); +} +/// \group relop +template +inline constexpr bool operator>=(const optional &lhs, + const optional &rhs) { + return !rhs.has_value() || (lhs.has_value() && *lhs >= *rhs); +} + +/// \group relop_nullopt +/// \brief Compares an optional to a `nullopt` +/// \details Equivalent to comparing the optional to an empty optional +template +inline constexpr bool operator==(const optional &lhs, nullopt_t) noexcept { + return !lhs.has_value(); +} +/// \group relop_nullopt +template +inline constexpr bool operator==(nullopt_t, const optional &rhs) noexcept { + return !rhs.has_value(); +} +/// \group relop_nullopt +template +inline constexpr bool operator!=(const optional &lhs, nullopt_t) noexcept { + return lhs.has_value(); +} +/// \group relop_nullopt +template +inline constexpr bool operator!=(nullopt_t, const optional &rhs) noexcept { + return rhs.has_value(); +} +/// \group relop_nullopt +template +inline constexpr bool operator<(const optional &, nullopt_t) noexcept { + return false; +} +/// \group relop_nullopt +template +inline constexpr bool operator<(nullopt_t, const optional &rhs) noexcept { + return rhs.has_value(); +} +/// \group relop_nullopt +template +inline constexpr bool operator<=(const optional &lhs, nullopt_t) noexcept { + return !lhs.has_value(); +} +/// \group relop_nullopt +template +inline constexpr bool operator<=(nullopt_t, const optional &) noexcept { + return true; +} +/// \group relop_nullopt +template +inline constexpr bool operator>(const optional &lhs, nullopt_t) noexcept { + return lhs.has_value(); +} +/// \group relop_nullopt +template +inline constexpr bool operator>(nullopt_t, const optional &) noexcept { + return false; +} +/// \group relop_nullopt +template +inline constexpr bool operator>=(const optional &, nullopt_t) noexcept { + return true; +} +/// \group relop_nullopt +template +inline constexpr bool operator>=(nullopt_t, const optional &rhs) noexcept { + return !rhs.has_value(); +} + +/// \group relop_t +/// \brief Compares the optional with a value. +/// \details If the optional has a value, it is compared with the other value +/// using `T`s relational operators. Otherwise, the optional is considered +/// less than the value. +template +inline constexpr bool operator==(const optional &lhs, const U &rhs) { + return lhs.has_value() ? *lhs == rhs : false; +} +/// \group relop_t +template +inline constexpr bool operator==(const U &lhs, const optional &rhs) { + return rhs.has_value() ? lhs == *rhs : false; +} +/// \group relop_t +template +inline constexpr bool operator!=(const optional &lhs, const U &rhs) { + return lhs.has_value() ? *lhs != rhs : true; +} +/// \group relop_t +template +inline constexpr bool operator!=(const U &lhs, const optional &rhs) { + return rhs.has_value() ? lhs != *rhs : true; +} +/// \group relop_t +template +inline constexpr bool operator<(const optional &lhs, const U &rhs) { + return lhs.has_value() ? *lhs < rhs : true; +} +/// \group relop_t +template +inline constexpr bool operator<(const U &lhs, const optional &rhs) { + return rhs.has_value() ? lhs < *rhs : false; +} +/// \group relop_t +template +inline constexpr bool operator<=(const optional &lhs, const U &rhs) { + return lhs.has_value() ? *lhs <= rhs : true; +} +/// \group relop_t +template +inline constexpr bool operator<=(const U &lhs, const optional &rhs) { + return rhs.has_value() ? lhs <= *rhs : false; +} +/// \group relop_t +template +inline constexpr bool operator>(const optional &lhs, const U &rhs) { + return lhs.has_value() ? *lhs > rhs : false; +} +/// \group relop_t +template +inline constexpr bool operator>(const U &lhs, const optional &rhs) { + return rhs.has_value() ? lhs > *rhs : true; +} +/// \group relop_t +template +inline constexpr bool operator>=(const optional &lhs, const U &rhs) { + return lhs.has_value() ? *lhs >= rhs : false; +} +/// \group relop_t +template +inline constexpr bool operator>=(const U &lhs, const optional &rhs) { + return rhs.has_value() ? lhs >= *rhs : true; +} + +/// \synopsis template \nvoid swap(optional &lhs, optional &rhs); +template ::value> * = nullptr, + detail::enable_if_t::value> * = nullptr> +void swap(optional &lhs, + optional &rhs) noexcept(noexcept(lhs.swap(rhs))) { + return lhs.swap(rhs); +} + +namespace detail { +struct i_am_secret {}; +} // namespace detail + +template ::value, + detail::decay_t, T>> +inline constexpr optional make_optional(U &&v) { + return optional(std::forward(v)); +} + +template +inline constexpr optional make_optional(Args &&... args) { + return optional(in_place, std::forward(args)...); +} +template +inline constexpr optional make_optional(std::initializer_list il, + Args &&... args) { + return optional(in_place, il, std::forward(args)...); +} + +#if __cplusplus >= 201703L +template optional(T)->optional; +#endif + +/// \exclude +namespace detail { +<<<<<<< Updated upstream +#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) && \ + !defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55) +======= +#ifdef TL_OPTIONAL_CXX14 +>>>>>>> Stashed changes +template (), + *std::declval())), + detail::enable_if_t::value> * = nullptr> +constexpr auto optional_map_impl(Opt &&opt, F &&f) { + return opt.has_value() + ? detail::invoke(std::forward(f), *std::forward(opt)) + : optional>(nullopt); +} + +template (), + *std::declval())), + detail::enable_if_t::value> * = nullptr> +auto optional_map_impl(Opt &&opt, F &&f) { + if (opt.has_value()) { + detail::invoke(std::forward(f), *std::forward(opt)); + return make_optional(monostate{}); + } + + return optional(nullopt); +} +#else +template (), + *std::declval())), + detail::enable_if_t::value> * = nullptr> + +constexpr auto optional_map_impl(Opt &&opt, F &&f) -> optional> { + return opt.has_value() + ? detail::invoke(std::forward(f), *std::forward(opt)) + : optional>(nullopt); +} + +template (), + *std::declval())), + detail::enable_if_t::value> * = nullptr> + +auto optional_map_impl(Opt &&opt, F &&f) -> optional { + if (opt.has_value()) { + detail::invoke(std::forward(f), *std::forward(opt)); + return monostate{}; + } + + return nullopt; +} +#endif +} // namespace detail + +/// Specialization for when `T` is a reference. `optional` acts similarly +/// to a `T*`, but provides more operations and shows intent more clearly. +/// +/// *Examples*: +/// +/// ``` +/// int i = 42; +/// tl::optional o = i; +/// *o == 42; //true +/// i = 12; +/// *o = 12; //true +/// &*o == &i; //true +/// ``` +/// +/// Assignment has rebind semantics rather than assign-through semantics: +/// +/// ``` +/// int j = 8; +/// o = j; +/// +/// &*o == &j; //true +/// ``` +template class optional { +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) + /// \group and_then + /// Carries out some operation which returns an optional on the stored + /// object if there is one. \requires `std::invoke(std::forward(f), + /// value())` returns a `std::optional` for some `U`. \returns Let `U` be + /// the result of `std::invoke(std::forward(f), value())`. Returns a + /// `std::optional`. The return value is empty if `*this` is empty, + /// otherwise the return value of `std::invoke(std::forward(f), value())` + /// is returned. + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) &; + template TL_OPTIONAL_11_CONSTEXPR auto and_then(F &&f) & { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } + + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) &&; + template TL_OPTIONAL_11_CONSTEXPR auto and_then(F &&f) && { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } + + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) const &; + template constexpr auto and_then(F &&f) const & { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) const &&; + template constexpr auto and_then(F &&f) const && { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } +#endif +#else + /// \group and_then + /// Carries out some operation which returns an optional on the stored + /// object if there is one. \requires `std::invoke(std::forward(f), + /// value())` returns a `std::optional` for some `U`. \returns Let `U` be + /// the result of `std::invoke(std::forward(f), value())`. Returns a + /// `std::optional`. The return value is empty if `*this` is empty, + /// otherwise the return value of `std::invoke(std::forward(f), value())` + /// is returned. + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) &; + template + TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t and_then(F &&f) & { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } + + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) &&; + template + TL_OPTIONAL_11_CONSTEXPR detail::invoke_result_t and_then(F &&f) && { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } + + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) const &; + template + constexpr detail::invoke_result_t and_then(F &&f) const & { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group and_then + /// \synopsis template \nconstexpr auto and_then(F &&f) const &&; + template + constexpr detail::invoke_result_t and_then(F &&f) const && { + using result = detail::invoke_result_t; + static_assert(detail::is_optional::value, + "F must return an optional"); + + return has_value() ? detail::invoke(std::forward(f), **this) + : result(nullopt); + } +#endif +#endif + +#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) && \ + !defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_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), + /// value())`. Returns a `std::optional`. The return value is empty if + /// `*this` is empty, otherwise an `optional` is constructed from the + /// return value of `std::invoke(std::forward(f), value())` and is + /// returned. + /// + /// \group map + /// \synopsis template constexpr auto map(F &&f) &; + template TL_OPTIONAL_11_CONSTEXPR auto map(F &&f) & { + return detail::optional_map_impl(*this, std::forward(f)); + } + + /// \group map + /// \synopsis template constexpr auto map(F &&f) &&; + template TL_OPTIONAL_11_CONSTEXPR auto map(F &&f) && { + return detail::optional_map_impl(std::move(*this), std::forward(f)); + } + + /// \group map + /// \synopsis template constexpr auto map(F &&f) const&; + template constexpr auto map(F &&f) const & { + return detail::optional_map_impl(*this, std::forward(f)); + } + + /// \group map + /// \synopsis template constexpr auto map(F &&f) const&&; + template constexpr auto map(F &&f) const && { + return detail::optional_map_impl(std::move(*this), std::forward(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), + /// value())`. Returns a `std::optional`. The return value is empty if + /// `*this` is empty, otherwise an `optional` is constructed from the + /// return value of `std::invoke(std::forward(f), value())` and is + /// returned. + /// + /// \group map + /// \synopsis template auto map(F &&f) &; + template + TL_OPTIONAL_11_CONSTEXPR decltype(detail::optional_map_impl(std::declval(), + std::declval())) + map(F &&f) & { + return detail::optional_map_impl(*this, std::forward(f)); + } + + /// \group map + /// \synopsis template auto map(F &&f) &&; + template + TL_OPTIONAL_11_CONSTEXPR decltype(detail::optional_map_impl(std::declval(), + std::declval())) + map(F &&f) && { + return detail::optional_map_impl(std::move(*this), std::forward(f)); + } + + /// \group map + /// \synopsis template auto map(F &&f) const&; + template + constexpr decltype(detail::optional_map_impl(std::declval(), + std::declval())) + map(F &&f) const & { + return detail::optional_map_impl(*this, std::forward(f)); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group map + /// \synopsis template auto map(F &&f) const&&; + template + constexpr decltype(detail::optional_map_impl(std::declval(), + std::declval())) + map(F &&f) const && { + return detail::optional_map_impl(std::move(*this), std::forward(f)); + } +#endif +#endif + + /// \brief Calls `f` if the optional is empty + /// \requires `std::invoke_result_t` must be void or convertible to + /// `optional`. \effects If `*this` has a value, returns `*this`. + /// Otherwise, if `f` returns `void`, calls `std::forward(f)` and returns + /// `std::nullopt`. Otherwise, returns `std::forward(f)()`. + /// + /// \group or_else + /// \synopsis template optional or_else (F &&f) &; + template * = nullptr> + optional TL_OPTIONAL_11_CONSTEXPR or_else(F &&f) & { + if (has_value()) + return *this; + + std::forward(f)(); + return nullopt; + } + + /// \exclude + template * = nullptr> + optional TL_OPTIONAL_11_CONSTEXPR or_else(F &&f) & { + return has_value() ? *this : std::forward(f)(); + } + + /// \group or_else + /// \synopsis template optional or_else (F &&f) &&; + template * = nullptr> + optional or_else(F &&f) && { + if (has_value()) + return std::move(*this); + + std::forward(f)(); + return nullopt; + } + + /// \exclude + template * = nullptr> + optional TL_OPTIONAL_11_CONSTEXPR or_else(F &&f) && { + return has_value() ? std::move(*this) : std::forward(f)(); + } + + /// \group or_else + /// \synopsis template optional or_else (F &&f) const &; + template * = nullptr> + optional or_else(F &&f) const & { + if (has_value()) + return *this; + + std::forward(f)(); + return nullopt; + } + + /// \exclude + template * = nullptr> + optional TL_OPTIONAL_11_CONSTEXPR or_else(F &&f) const & { + return has_value() ? *this : std::forward(f)(); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \exclude + template * = nullptr> + optional or_else(F &&f) const && { + if (has_value()) + return std::move(*this); + + std::forward(f)(); + return nullopt; + } + + /// \exclude + template * = nullptr> + optional or_else(F &&f) const && { + return has_value() ? std::move(*this) : std::forward(f)(); + } +#endif + + /// \brief Maps the stored value with `f` if there is one, otherwise returns + /// `u`. + /// + /// \details If there is a value stored, then `f` is called with `**this` + /// and the value is returned. Otherwise `u` is returned. + /// + /// \group map_or + template U map_or(F &&f, U &&u) & { + return has_value() ? detail::invoke(std::forward(f), **this) + : std::forward(u); + } + + /// \group map_or + template U map_or(F &&f, U &&u) && { + return has_value() ? detail::invoke(std::forward(f), std::move(**this)) + : std::forward(u); + } + + /// \group map_or + template U map_or(F &&f, U &&u) const & { + return has_value() ? detail::invoke(std::forward(f), **this) + : std::forward(u); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group map_or + template U map_or(F &&f, U &&u) const && { + return has_value() ? detail::invoke(std::forward(f), std::move(**this)) + : std::forward(u); + } +#endif + + /// \brief Maps the stored value with `f` if there is one, otherwise calls + /// `u` and returns the result. + /// + /// \details If there is a value stored, then `f` is + /// called with `**this` and the value is returned. Otherwise + /// `std::forward(u)()` is returned. + /// + /// \group map_or_else + /// \synopsis template \nauto map_or_else(F &&f, U &&u) &; + template + detail::invoke_result_t map_or_else(F &&f, U &&u) & { + return has_value() ? detail::invoke(std::forward(f), **this) + : std::forward(u)(); + } + + /// \group map_or_else + /// \synopsis template \nauto map_or_else(F &&f, U &&u) + /// &&; + template + detail::invoke_result_t map_or_else(F &&f, U &&u) && { + return has_value() ? detail::invoke(std::forward(f), std::move(**this)) + : std::forward(u)(); + } + + /// \group map_or_else + /// \synopsis template \nauto map_or_else(F &&f, U &&u) + /// const &; + template + detail::invoke_result_t map_or_else(F &&f, U &&u) const & { + return has_value() ? detail::invoke(std::forward(f), **this) + : std::forward(u)(); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group map_or_else + /// \synopsis template \nauto map_or_else(F &&f, U &&u) + /// const &&; + template + detail::invoke_result_t map_or_else(F &&f, U &&u) const && { + return has_value() ? detail::invoke(std::forward(f), std::move(**this)) + : std::forward(u)(); + } +#endif + + /// \returns `u` if `*this` has a value, otherwise an empty optional. + template + constexpr optional::type> conjunction(U &&u) const { + using result = optional>; + return has_value() ? result{u} : result{nullopt}; + } + + /// \returns `rhs` if `*this` is empty, otherwise the current value. + /// \group disjunction + TL_OPTIONAL_11_CONSTEXPR optional disjunction(const optional &rhs) & { + return has_value() ? *this : rhs; + } + + /// \group disjunction + constexpr optional disjunction(const optional &rhs) const & { + return has_value() ? *this : rhs; + } + + /// \group disjunction + TL_OPTIONAL_11_CONSTEXPR optional disjunction(const optional &rhs) && { + return has_value() ? std::move(*this) : rhs; + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group disjunction + constexpr optional disjunction(const optional &rhs) const && { + return has_value() ? std::move(*this) : rhs; + } +#endif + + /// \group disjunction + TL_OPTIONAL_11_CONSTEXPR optional disjunction(optional &&rhs) & { + return has_value() ? *this : std::move(rhs); + } + + /// \group disjunction + constexpr optional disjunction(optional &&rhs) const & { + return has_value() ? *this : std::move(rhs); + } + + /// \group disjunction + TL_OPTIONAL_11_CONSTEXPR optional disjunction(optional &&rhs) && { + return has_value() ? std::move(*this) : std::move(rhs); + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group disjunction + 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 + /// \group take + optional take() & { + optional ret = *this; + reset(); + return ret; + } + + /// \group take + optional take() const & { + optional ret = *this; + reset(); + return ret; + } + + /// \group take + optional take() && { + optional ret = std::move(*this); + reset(); + return ret; + } + +#ifndef TL_OPTIONAL_NO_CONSTRR + /// \group take + optional take() const && { + optional ret = std::move(*this); + reset(); + return ret; + } +#endif + + using value_type = T &; + + /// Constructs an optional that does not contain a value. + /// \group ctor_empty + constexpr optional() noexcept : m_value(nullptr) {} + + /// \group ctor_empty + 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`. + /// \synopsis template constexpr optional(U &&u); + template >::value> + * = nullptr> + constexpr optional(U &&u) : m_value(std::addressof(u)) { + static_assert(std::is_lvalue_reference::value, "U must be an lvalue"); + } + + /// \exclude + template + constexpr explicit optional(const optional &rhs) : 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`. + /// + /// \requires `U` must be an lvalue reference. + /// \synopsis optional &operator=(U &&u); + template >::value> + * = nullptr> + optional &operator=(U &&u) { + static_assert(std::is_lvalue_reference::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 optional &operator=(const optional &rhs) { + m_value = std::addressof(rhs.value()); + return *this; + } + + /// Constructs the value in-place, destroying the current one if there is + /// one. + /// + /// \group emplace + template T &emplace(Args &&... args) noexcept { + static_assert(std::is_constructible::value, + "T must be constructible with Args"); + + *this = nullopt; + this->construct(std::forward(args)...); + } + + /// 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::swap(m_value, rhs.m_value); } + + /// \returns a pointer to the stored value + /// \requires a value is stored + /// \group pointer + /// \synopsis constexpr const T *operator->() const; + constexpr const T *operator->() const { return m_value; } + + /// \group pointer + /// \synopsis constexpr T *operator->(); + TL_OPTIONAL_11_CONSTEXPR T *operator->() { return m_value; } + + /// \returns the stored value + /// \requires a value is stored + /// \group deref + /// \synopsis constexpr T &operator*(); + TL_OPTIONAL_11_CONSTEXPR T &operator*() { return *m_value; } + + /// \group deref + /// \synopsis constexpr const T &operator*() const; + constexpr const T &operator*() const { return *m_value; } + + /// \returns whether or not the optional has a value + /// \group has_value + constexpr bool has_value() const noexcept { return m_value != nullptr; } + + /// \group has_value + constexpr explicit operator bool() const noexcept { + return m_value != nullptr; + } + + /// \returns the contained value if there is one, otherwise throws + /// [bad_optional_access] + /// \group value + /// synopsis constexpr T &value(); + TL_OPTIONAL_11_CONSTEXPR T &value() { + if (has_value()) + return *m_value; + throw bad_optional_access(); + } + /// \group value + /// \synopsis constexpr const T &value() const; + 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` + /// \group value_or + template constexpr T value_or(U &&u) const & { + static_assert(std::is_copy_constructible::value && + std::is_convertible::value, + "T must be copy constructible and convertible from U"); + return has_value() ? **this : static_cast(std::forward(u)); + } + + /// \group value_or + template TL_OPTIONAL_11_CONSTEXPR T value_or(U &&u) && { + static_assert(std::is_move_constructible::value && + std::is_convertible::value, + "T must be move constructible and convertible from U"); + return has_value() ? **this : static_cast(std::forward(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 struct hash> { + ::std::size_t operator()(const tl::optional &o) const { + if (!o.has_value()) + return 0; + + return std::hash>()(*o); + } +}; +} // namespace std + +#endif