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2499 lines
76 KiB
C++
2499 lines
76 KiB
C++
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///
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// optional - An implementation of std::optional with extensions
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// Written in 2017 by Sy Brand (tartanllama@gmail.com, @TartanLlama)
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//
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// Documentation available at https://tl.tartanllama.xyz/
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//
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// To the extent possible under law, the author(s) have dedicated all
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// copyright and related and neighboring rights to this software to the
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// public domain worldwide. This software is distributed without any warranty.
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//
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// You should have received a copy of the CC0 Public Domain Dedication
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// along with this software. If not, see
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// <http://creativecommons.org/publicdomain/zero/1.0/>.
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///
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#ifndef TL_OPTIONAL_HPP
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#define TL_OPTIONAL_HPP
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#define TL_OPTIONAL_VERSION_MAJOR 1
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#define TL_OPTIONAL_VERSION_MINOR 1
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#define TL_OPTIONAL_VERSION_PATCH 0
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#include <exception>
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#include <functional>
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#include <memory>
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#include <new>
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#include <type_traits>
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#include <utility>
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#if (defined(_MSC_VER) && _MSC_VER == 1900)
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#define TL_OPTIONAL_MSVC2015
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#endif
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#if (defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 \
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&& !defined(__clang__))
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#define TL_OPTIONAL_GCC49
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#endif
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#if (defined(__GNUC__) && __GNUC__ == 5 && __GNUC_MINOR__ <= 4 \
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&& !defined(__clang__))
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#define TL_OPTIONAL_GCC54
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#endif
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#if (defined(__GNUC__) && __GNUC__ == 5 && __GNUC_MINOR__ <= 5 \
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&& !defined(__clang__))
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#define TL_OPTIONAL_GCC55
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#endif
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#if (defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ <= 9 \
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&& !defined(__clang__))
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// GCC < 5 doesn't support overloading on const&& for member functions
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#define TL_OPTIONAL_NO_CONSTRR
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// GCC < 5 doesn't support some standard C++11 type traits
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#define TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
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std::has_trivial_copy_constructor<T>::value
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#define TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
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std::has_trivial_copy_assign<T>::value
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// This one will be different for GCC 5.7 if it's ever supported
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#define TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T) \
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std::is_trivially_destructible<T>::value
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// GCC 5 < v < 8 has a bug in is_trivially_copy_constructible which breaks std::vector
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// for non-copyable types
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#elif (defined(__GNUC__) && __GNUC__ < 8 && !defined(__clang__))
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#ifndef TL_GCC_LESS_8_TRIVIALLY_COPY_CONSTRUCTIBLE_MUTEX
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#define TL_GCC_LESS_8_TRIVIALLY_COPY_CONSTRUCTIBLE_MUTEX
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namespace tl {
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namespace detail {
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template<class T>
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struct is_trivially_copy_constructible
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: std::is_trivially_copy_constructible<T> {};
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#ifdef _GLIBCXX_VECTOR
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template<class T, class A>
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struct is_trivially_copy_constructible<std::vector<T, A>>
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: std::is_trivially_copy_constructible<T> {};
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#endif
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}// namespace detail
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}// namespace tl
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#endif
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#define TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
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tl::detail::is_trivially_copy_constructible<T>::value
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#define TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
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std::is_trivially_copy_assignable<T>::value
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#define TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T) \
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std::is_trivially_destructible<T>::value
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#else
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#define TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) \
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std::is_trivially_copy_constructible<T>::value
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#define TL_OPTIONAL_IS_TRIVIALLY_COPY_ASSIGNABLE(T) \
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std::is_trivially_copy_assignable<T>::value
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#define TL_OPTIONAL_IS_TRIVIALLY_DESTRUCTIBLE(T) \
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std::is_trivially_destructible<T>::value
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#endif
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#if __cplusplus > 201103L
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#define TL_OPTIONAL_CXX14
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#endif
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// constexpr implies const in C++11, not C++14
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#if (__cplusplus == 201103L || defined(TL_OPTIONAL_MSVC2015) \
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|| defined(TL_OPTIONAL_GCC49))
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#define TL_OPTIONAL_11_CONSTEXPR
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#else
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#define TL_OPTIONAL_11_CONSTEXPR constexpr
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#endif
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namespace tl {
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#ifndef TL_MONOSTATE_INPLACE_MUTEX
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#define TL_MONOSTATE_INPLACE_MUTEX
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/// Used to represent an optional with no data; essentially a bool
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class monostate {};
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/// A tag type to tell optional to construct its value in-place
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struct in_place_t {
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explicit in_place_t() = default;
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};
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/// A tag to tell optional to construct its value in-place
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static constexpr in_place_t in_place{};
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#endif
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template<class T>
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class optional;
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namespace detail {
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#ifndef TL_TRAITS_MUTEX
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#define TL_TRAITS_MUTEX
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// C++14-style aliases for brevity
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template<class T>
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using remove_const_t = typename std::remove_const<T>::type;
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template<class T>
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using remove_reference_t = typename std::remove_reference<T>::type;
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template<class T>
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using decay_t = typename std::decay<T>::type;
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template<bool E, class T = void>
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using enable_if_t = typename std::enable_if<E, T>::type;
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template<bool B, class T, class F>
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using conditional_t = typename std::conditional<B, T, F>::type;
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// std::conjunction from C++17
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template<class...>
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struct conjunction : std::true_type {};
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template<class B>
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struct conjunction<B> : B {};
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template<class B, class... Bs>
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struct conjunction<B, Bs...>
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: std::conditional<bool(B::value), conjunction<Bs...>, B>::type {};
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#if defined(_LIBCPP_VERSION) && __cplusplus == 201103L
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#define TL_TRAITS_LIBCXX_MEM_FN_WORKAROUND
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#endif
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// In C++11 mode, there's an issue in libc++'s std::mem_fn
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// which results in a hard-error when using it in a noexcept expression
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// in some cases. This is a check to workaround the common failing case.
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#ifdef TL_TRAITS_LIBCXX_MEM_FN_WORKAROUND
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template<class T>
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struct is_pointer_to_non_const_member_func : std::false_type {};
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template<class T, class Ret, class... Args>
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struct is_pointer_to_non_const_member_func<Ret (T::*)(Args...)>
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: std::true_type {};
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template<class T, class Ret, class... Args>
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struct is_pointer_to_non_const_member_func<Ret (T::*)(Args...) &>
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: std::true_type {};
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template<class T, class Ret, class... Args>
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struct is_pointer_to_non_const_member_func<Ret (T::*)(Args...) &&>
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: std::true_type {};
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template<class T, class Ret, class... Args>
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struct is_pointer_to_non_const_member_func<Ret (T::*)(Args...) volatile>
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: std::true_type {};
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template<class T, class Ret, class... Args>
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struct is_pointer_to_non_const_member_func<Ret (T::*)(Args...) volatile &>
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: std::true_type {};
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template<class T, class Ret, class... Args>
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struct is_pointer_to_non_const_member_func<Ret (T::*)(Args...) volatile &&>
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: std::true_type {};
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template<class T>
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struct is_const_or_const_ref : std::false_type {};
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template<class T>
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struct is_const_or_const_ref<T const &> : std::true_type {};
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template<class T>
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struct is_const_or_const_ref<T const> : std::true_type {};
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#endif
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// std::invoke from C++17
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// https://stackoverflow.com/questions/38288042/c11-14-invoke-workaround
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template<typename Fn,
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typename... Args,
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#ifdef TL_TRAITS_LIBCXX_MEM_FN_WORKAROUND
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typename = enable_if_t<!(is_pointer_to_non_const_member_func<Fn>::value
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&& is_const_or_const_ref<Args...>::value)>,
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#endif
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typename = enable_if_t<std::is_member_pointer<decay_t<Fn>>::value>,
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int = 0>
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constexpr auto
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invoke(Fn &&f, Args &&...args) noexcept(
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noexcept(std::mem_fn(f)(std::forward<Args>(args)...)))
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-> decltype(std::mem_fn(f)(std::forward<Args>(args)...))
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{
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return std::mem_fn(f)(std::forward<Args>(args)...);
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}
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template<typename Fn,
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typename... Args,
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typename = enable_if_t<!std::is_member_pointer<decay_t<Fn>>::value>>
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constexpr auto
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invoke(Fn &&f, Args &&...args) noexcept(
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noexcept(std::forward<Fn>(f)(std::forward<Args>(args)...)))
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-> decltype(std::forward<Fn>(f)(std::forward<Args>(args)...))
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{
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return std::forward<Fn>(f)(std::forward<Args>(args)...);
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}
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// std::invoke_result from C++17
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template<class F, class, class... Us>
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struct invoke_result_impl;
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template<class F, class... Us>
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struct invoke_result_impl<
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F,
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decltype(detail::invoke(std::declval<F>(), std::declval<Us>()...), void()),
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Us...> {
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using type =
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decltype(detail::invoke(std::declval<F>(), std::declval<Us>()...));
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};
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template<class F, class... Us>
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using invoke_result = invoke_result_impl<F, void, Us...>;
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template<class F, class... Us>
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using invoke_result_t = typename invoke_result<F, Us...>::type;
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#if defined(_MSC_VER) && _MSC_VER <= 1900
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// TODO make a version which works with MSVC 2015
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template<class T, class U = T>
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struct is_swappable : std::true_type {};
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template<class T, class U = T>
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struct is_nothrow_swappable : std::true_type {};
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#else
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// https://stackoverflow.com/questions/26744589/what-is-a-proper-way-to-implement-is-swappable-to-test-for-the-swappable-concept
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namespace swap_adl_tests {
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// if swap ADL finds this then it would call std::swap otherwise (same
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// signature)
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struct tag {};
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template<class T>
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tag swap(T &, T &);
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template<class T, std::size_t N>
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tag swap(T (&a)[N], T (&b)[N]);
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// helper functions to test if an unqualified swap is possible, and if it
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// becomes std::swap
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template<class, class>
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std::false_type can_swap(...) noexcept(false);
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template<class T,
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class U,
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class = decltype(swap(std::declval<T &>(), std::declval<U &>()))>
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std::true_type can_swap(int) noexcept(noexcept(swap(std::declval<T &>(),
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std::declval<U &>())));
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template<class, class>
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std::false_type uses_std(...);
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template<class T, class U>
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std::is_same<decltype(swap(std::declval<T &>(), std::declval<U &>())), tag>
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uses_std(int);
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template<class T>
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struct is_std_swap_noexcept
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: std::integral_constant<bool,
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std::is_nothrow_move_constructible<T>::value
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&& std::is_nothrow_move_assignable<T>::value> {
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};
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template<class T, std::size_t N>
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struct is_std_swap_noexcept<T[N]> : is_std_swap_noexcept<T> {};
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template<class T, class U>
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struct is_adl_swap_noexcept
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: std::integral_constant<bool, noexcept(can_swap<T, U>(0))> {};
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}// namespace swap_adl_tests
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template<class T, class U = T>
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struct is_swappable
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: std::integral_constant<
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bool,
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decltype(detail::swap_adl_tests::can_swap<T, U>(0))::value
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&& (!decltype(detail::swap_adl_tests::uses_std<T, U>(0))::value
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|| (std::is_move_assignable<T>::value
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&& std::is_move_constructible<T>::value))> {};
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template<class T, std::size_t N>
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struct is_swappable<T[N], T[N]>
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: std::integral_constant<
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bool,
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decltype(detail::swap_adl_tests::can_swap<T[N], T[N]>(0))::value
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&& (!decltype(detail::swap_adl_tests::uses_std<T[N], T[N]>(
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0))::value
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|| is_swappable<T, T>::value)> {};
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template<class T, class U = T>
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struct is_nothrow_swappable
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: std::integral_constant<
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bool,
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is_swappable<T, U>::value
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&& ((decltype(detail::swap_adl_tests::uses_std<T, U>(0))::value
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&& detail::swap_adl_tests::is_std_swap_noexcept<T>::value)
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|| (!decltype(detail::swap_adl_tests::uses_std<T, U>(
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0))::value
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&& detail::swap_adl_tests::is_adl_swap_noexcept<T, U>::
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value))> {};
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#endif
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#endif
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// std::void_t from C++17
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template<class...>
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struct voider {
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using type = void;
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};
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template<class... Ts>
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using void_t = typename voider<Ts...>::type;
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// Trait for checking if a type is a tl::optional
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template<class T>
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struct is_optional_impl : std::false_type {};
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template<class T>
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struct is_optional_impl<optional<T>> : std::true_type {};
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template<class T>
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using is_optional = is_optional_impl<decay_t<T>>;
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// Change void to tl::monostate
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template<class U>
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using fixup_void = conditional_t<std::is_void<U>::value, monostate, U>;
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template<class F, class U, class = invoke_result_t<F, U>>
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using get_map_return = optional<fixup_void<invoke_result_t<F, U>>>;
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// Check if invoking F for some Us returns void
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template<class F, class = void, class... U>
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struct returns_void_impl;
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template<class F, class... U>
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struct returns_void_impl<F, void_t<invoke_result_t<F, U...>>, U...>
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: std::is_void<invoke_result_t<F, U...>> {};
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template<class F, class... U>
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using returns_void = returns_void_impl<F, void, U...>;
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template<class T, class... U>
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using enable_if_ret_void = enable_if_t<returns_void<T &&, U...>::value>;
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template<class T, class... U>
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using disable_if_ret_void = enable_if_t<!returns_void<T &&, U...>::value>;
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template<class T, class U>
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using enable_forward_value = detail::enable_if_t<
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std::is_constructible<T, U &&>::value
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&& !std::is_same<detail::decay_t<U>, in_place_t>::value
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&& !std::is_same<optional<T>, detail::decay_t<U>>::value>;
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template<class T, class U, class Other>
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using enable_from_other = detail::enable_if_t<
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std::is_constructible<T, Other>::value
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&& !std::is_constructible<T, optional<U> &>::value
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&& !std::is_constructible<T, optional<U> &&>::value
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&& !std::is_constructible<T, const optional<U> &>::value
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&& !std::is_constructible<T, const optional<U> &&>::value
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&& !std::is_convertible<optional<U> &, T>::value
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&& !std::is_convertible<optional<U> &&, T>::value
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&& !std::is_convertible<const optional<U> &, T>::value
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&& !std::is_convertible<const optional<U> &&, T>::value>;
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template<class T, class U>
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using enable_assign_forward = detail::enable_if_t<
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!std::is_same<optional<T>, detail::decay_t<U>>::value
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&& !detail::conjunction<std::is_scalar<T>,
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std::is_same<T, detail::decay_t<U>>>::value
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&& std::is_constructible<T, U>::value && std::is_assignable<T &, U>::value>;
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template<class T, class U, class Other>
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using enable_assign_from_other = detail::enable_if_t<
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std::is_constructible<T, Other>::value
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&& std::is_assignable<T &, Other>::value
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&& !std::is_constructible<T, optional<U> &>::value
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&& !std::is_constructible<T, optional<U> &&>::value
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&& !std::is_constructible<T, const optional<U> &>::value
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&& !std::is_constructible<T, const optional<U> &&>::value
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&& !std::is_convertible<optional<U> &, T>::value
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&& !std::is_convertible<optional<U> &&, T>::value
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&& !std::is_convertible<const optional<U> &, T>::value
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|
&& !std::is_convertible<const optional<U> &&, T>::value
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&& !std::is_assignable<T &, optional<U> &>::value
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&& !std::is_assignable<T &, optional<U> &&>::value
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|
&& !std::is_assignable<T &, const optional<U> &>::value
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&& !std::is_assignable<T &, const optional<U> &&>::value>;
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// The storage base manages the actual storage, and correctly propagates
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// trivial destruction from T. This case is for when T is not trivially
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// destructible.
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template<class T, bool = ::std::is_trivially_destructible<T>::value>
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struct optional_storage_base {
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TL_OPTIONAL_11_CONSTEXPR optional_storage_base() noexcept
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|
: m_dummy(),
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m_has_value(false)
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{}
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template<class... U>
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TL_OPTIONAL_11_CONSTEXPR optional_storage_base(in_place_t, U &&...u)
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: m_value(std::forward<U>(u)...),
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m_has_value(true)
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{}
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~optional_storage_base()
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{
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if (m_has_value) {
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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)
|
|
{
|
|
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();
|
|
}
|
|
}
|
|
|
|
else 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();
|
|
}
|
|
}
|
|
|
|
else 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() ? std::move(**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), 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 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);
|
|
}
|
|
};
|
|
|
|
// if <= C++14
|
|
#if __cplusplus < 201703L
|
|
template<typename T>
|
|
using optional = tl::optional<T>;
|
|
|
|
template<typename T>
|
|
using nullopt_t = tl::nullopt_t;
|
|
|
|
// make_optional
|
|
template<typename T>
|
|
constexpr tl::optional<tl::detail::decay_t<T>>
|
|
make_optional(T &&v)
|
|
{
|
|
return tl::make_optional(std::forward<T>(v));
|
|
}
|
|
|
|
template<typename T, typename... Args>
|
|
constexpr tl::optional<T>
|
|
make_optional(Args &&...args)
|
|
{
|
|
return tl::make_optional<T>(std::forward<Args>(args)...);
|
|
}
|
|
|
|
template<typename T, typename U, typename... Args>
|
|
constexpr tl::optional<T>
|
|
make_optional(std::initializer_list<U> il, Args &&...args)
|
|
{
|
|
return tl::make_optional<T>(il, std::forward<Args>(args)...);
|
|
}
|
|
|
|
constexpr tl::nullopt_t nullopt{tl::nullopt};
|
|
#endif
|
|
|
|
}// namespace std
|
|
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#endif
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