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3027 lines
90 KiB
C++
3027 lines
90 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 Simon Brand (@TartanLlama)
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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 0
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#define TL_OPTIONAL_VERSION_MINOR 5
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#include <exception>
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#include <functional>
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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
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// std::vector 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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{
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namespace detail
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{
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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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{
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};
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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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{
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};
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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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/// \exclude
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#define TL_OPTIONAL_11_CONSTEXPR
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#else
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/// \exclude
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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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{
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#ifndef TL_MONOSTATE_INPLACE_MUTEX
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#define TL_MONOSTATE_INPLACE_MUTEX
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/// \brief Used to represent an optional with no data; essentially a bool
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class monostate
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{
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};
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/// \brief A tag type to tell optional to construct its value in-place
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struct in_place_t
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{
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explicit in_place_t() = default;
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};
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/// \brief 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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/// \exclude
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namespace detail
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{
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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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{
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};
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template < class B >
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struct conjunction< B > : B
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{
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};
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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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{
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};
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#if defined(_LIBCPP_VERSION) && __cplusplus == 201103L
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#define TL_OPTIONAL_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_OPTIONAL_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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{
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};
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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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{
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};
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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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{
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};
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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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{
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};
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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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{
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};
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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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{
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};
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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::*)(
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Args...) volatile && > : std::true_type
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{
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};
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template < class T >
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struct is_const_or_const_ref : std::false_type
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{
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};
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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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{
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};
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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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{
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};
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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 <
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typename Fn, typename... Args,
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#ifdef TL_OPTIONAL_LIBCXX_MEM_FN_WORKAROUND
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typename =
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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 =
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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, typename... Args,
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typename = enable_if_t<
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!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< F,
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decltype(detail::invoke(std::declval< F >(),
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std::declval< Us >()...),
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void()),
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Us... >
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{
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using type = decltype(
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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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#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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{
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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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{
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};
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template < class T >
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struct is_optional_impl< optional< T > > : std::true_type
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{
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};
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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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{
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};
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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 =
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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<
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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
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&& 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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#ifdef _MSC_VER
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// TODO make a version which works with MSVC
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template < class T, class U = T >
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struct is_swappable : std::true_type
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{
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};
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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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{
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};
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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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{
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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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{
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};
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template < class T >
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tag
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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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|
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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
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can_swap(...) noexcept(false);
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template < class T, class U,
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class = decltype(swap(std::declval< T & >(),
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std::declval< U & >())) >
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std::true_type
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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
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uses_std(...);
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template < class T, class U >
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std::is_same<
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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<
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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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};
|
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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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|
{
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};
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|
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|
template < class T, class U >
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|
struct is_adl_swap_noexcept
|
|
: std::integral_constant< bool, noexcept(can_swap< T, U >(0)) >
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|
{
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|
};
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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(
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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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{
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};
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|
|
template < class T, std::size_t N >
|
|
struct is_swappable< T[N], T[N] >
|
|
: 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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{
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};
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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 >(
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0))::value &&detail::swap_adl_tests::
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|
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 &&detail::swap_adl_tests::
|
|
is_adl_swap_noexcept< T, U >::value)) >
|
|
{
|
|
};
|
|
#endif
|
|
|
|
// The storage base manages the actual storage, and correctly propagates
|
|
// trivial destruction from T. This case is for when T is not trivially
|
|
// destructible.
|
|
template < class T, bool = ::std::is_trivially_destructible< T >::value >
|
|
struct optional_storage_base
|
|
{
|
|
TL_OPTIONAL_11_CONSTEXPR
|
|
optional_storage_base() noexcept : m_dummy(), m_has_value(false)
|
|
{
|
|
}
|
|
|
|
template < class... U >
|
|
TL_OPTIONAL_11_CONSTEXPR
|
|
optional_storage_base(in_place_t, U &&... u)
|
|
: m_value(std::forward< U >(u)...), m_has_value(true)
|
|
{
|
|
}
|
|
|
|
~optional_storage_base()
|
|
{
|
|
if(m_has_value)
|
|
{
|
|
m_value.~T();
|
|
m_has_value = false;
|
|
}
|
|
}
|
|
|
|
struct dummy
|
|
{
|
|
};
|
|
union {
|
|
dummy m_dummy;
|
|
T m_value;
|
|
};
|
|
|
|
bool m_has_value;
|
|
};
|
|
|
|
// This case is for when T is trivially destructible.
|
|
template < class T >
|
|
struct optional_storage_base< T, true >
|
|
{
|
|
TL_OPTIONAL_11_CONSTEXPR
|
|
optional_storage_base() noexcept : m_dummy(), m_has_value(false)
|
|
{
|
|
}
|
|
|
|
template < class... U >
|
|
TL_OPTIONAL_11_CONSTEXPR
|
|
optional_storage_base(in_place_t, U &&... u)
|
|
: m_value(std::forward< U >(u)...), m_has_value(true)
|
|
{
|
|
}
|
|
|
|
// No destructor, so this class is trivially destructible
|
|
|
|
struct dummy
|
|
{
|
|
};
|
|
union {
|
|
dummy m_dummy;
|
|
T m_value;
|
|
};
|
|
|
|
bool m_has_value = false;
|
|
};
|
|
|
|
// This base class provides some handy member functions which can be used in
|
|
// further derived classes
|
|
template < class T >
|
|
struct optional_operations_base : optional_storage_base< T >
|
|
{
|
|
using optional_storage_base< T >::optional_storage_base;
|
|
|
|
void
|
|
hard_reset() noexcept
|
|
{
|
|
get().~T();
|
|
this->m_has_value = false;
|
|
}
|
|
|
|
template < class... Args >
|
|
void
|
|
construct(Args &&... args) noexcept
|
|
{
|
|
new(std::addressof(this->m_value)) T(std::forward< Args >(args)...);
|
|
this->m_has_value = true;
|
|
}
|
|
|
|
template < class Opt >
|
|
void
|
|
assign(Opt &&rhs)
|
|
{
|
|
if(this->has_value())
|
|
{
|
|
if(rhs.has_value())
|
|
{
|
|
this->m_value = std::forward< Opt >(rhs).get();
|
|
}
|
|
else
|
|
{
|
|
this->m_value.~T();
|
|
this->m_has_value = false;
|
|
}
|
|
}
|
|
|
|
else if(rhs.has_value())
|
|
{
|
|
construct(std::forward< Opt >(rhs).get());
|
|
}
|
|
}
|
|
|
|
bool
|
|
has_value() const
|
|
{
|
|
return this->m_has_value;
|
|
}
|
|
|
|
TL_OPTIONAL_11_CONSTEXPR T &
|
|
get() &
|
|
{
|
|
return this->m_value;
|
|
}
|
|
TL_OPTIONAL_11_CONSTEXPR const T &
|
|
get() const &
|
|
{
|
|
return this->m_value;
|
|
}
|
|
TL_OPTIONAL_11_CONSTEXPR T &&
|
|
get() &&
|
|
{
|
|
return std::move(this->m_value);
|
|
}
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
constexpr const T &&
|
|
get() const &&
|
|
{
|
|
return std::move(this->m_value);
|
|
}
|
|
#endif
|
|
};
|
|
|
|
// This class manages conditionally having a trivial copy constructor
|
|
// This specialization is for when T is trivially copy constructible
|
|
template < class T, bool = TL_OPTIONAL_IS_TRIVIALLY_COPY_CONSTRUCTIBLE(T) >
|
|
struct optional_copy_base : optional_operations_base< T >
|
|
{
|
|
using optional_operations_base< T >::optional_operations_base;
|
|
};
|
|
|
|
// This specialization is for when T is not trivially copy constructible
|
|
template < class T >
|
|
struct optional_copy_base< T, false > : optional_operations_base< T >
|
|
{
|
|
using optional_operations_base< T >::optional_operations_base;
|
|
|
|
optional_copy_base() = default;
|
|
optional_copy_base(const optional_copy_base &rhs)
|
|
{
|
|
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
|
|
|
|
/// \brief A tag type to represent an empty optional
|
|
struct nullopt_t
|
|
{
|
|
struct do_not_use
|
|
{
|
|
};
|
|
constexpr explicit nullopt_t(do_not_use, do_not_use) noexcept
|
|
{
|
|
}
|
|
};
|
|
/// \brief Represents an empty optional
|
|
/// \synopsis static constexpr nullopt_t nullopt;
|
|
///
|
|
/// *Examples*:
|
|
/// ```
|
|
/// tl::optional<int> a = tl::nullopt;
|
|
/// void foo (tl::optional<int>);
|
|
/// foo(tl::nullopt); //pass an empty optional
|
|
/// ```
|
|
static constexpr nullopt_t nullopt{nullopt_t::do_not_use{},
|
|
nullopt_t::do_not_use{}};
|
|
|
|
class bad_optional_access : public std::exception
|
|
{
|
|
public:
|
|
bad_optional_access() = default;
|
|
const char *
|
|
what() const noexcept
|
|
{
|
|
return "Optional has no value";
|
|
}
|
|
};
|
|
|
|
/// An optional object is an object that contains the storage for another
|
|
/// object and manages the lifetime of this contained object, if any. The
|
|
/// contained object may be initialized after the optional object has been
|
|
/// initialized, and may be destroyed before the optional object has been
|
|
/// destroyed. The initialization state of the contained object is tracked by
|
|
/// the optional object.
|
|
template < class 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)
|
|
/// \group and_then
|
|
/// Carries out some operation which returns an optional on the stored
|
|
/// object if there is one. \requires `std::invoke(std::forward<F>(f),
|
|
/// value())` returns a `std::optional<U>` for some `U`. \returns Let `U` be
|
|
/// the result of `std::invoke(std::forward<F>(f), value())`. Returns a
|
|
/// `std::optional<U>`. The return value is empty if `*this` is empty,
|
|
/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
|
|
/// is returned.
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
|
|
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);
|
|
}
|
|
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
|
|
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);
|
|
}
|
|
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &;
|
|
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
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
|
|
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
|
|
/// \group and_then
|
|
/// Carries out some operation which returns an optional on the stored
|
|
/// object if there is one. \requires `std::invoke(std::forward<F>(f),
|
|
/// value())` returns a `std::optional<U>` for some `U`.
|
|
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
|
|
/// value())`. Returns a `std::optional<U>`. The return value is empty if
|
|
/// `*this` is empty, otherwise the return value of
|
|
/// `std::invoke(std::forward<F>(f), value())` is returned.
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
|
|
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);
|
|
}
|
|
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
|
|
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);
|
|
}
|
|
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &;
|
|
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
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
|
|
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)
|
|
/// \brief Carries out some operation on the stored object if there is one.
|
|
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
|
|
/// value())`. Returns a `std::optional<U>`. The return value is empty if
|
|
/// `*this` is empty, otherwise an `optional<U>` is constructed from the
|
|
/// return value of `std::invoke(std::forward<F>(f), value())` and is
|
|
/// returned.
|
|
///
|
|
/// \group map
|
|
/// \synopsis template <class F> constexpr auto map(F &&f) &;
|
|
template < class F >
|
|
TL_OPTIONAL_11_CONSTEXPR auto
|
|
map(F &&f) &
|
|
{
|
|
return optional_map_impl(*this, std::forward< F >(f));
|
|
}
|
|
|
|
/// \group map
|
|
/// \synopsis template <class F> constexpr auto map(F &&f) &&;
|
|
template < class F >
|
|
TL_OPTIONAL_11_CONSTEXPR auto
|
|
map(F &&f) &&
|
|
{
|
|
return optional_map_impl(std::move(*this), std::forward< F >(f));
|
|
}
|
|
|
|
/// \group map
|
|
/// \synopsis template <class F> constexpr auto map(F &&f) const&;
|
|
template < class F >
|
|
constexpr auto
|
|
map(F &&f) const &
|
|
{
|
|
return optional_map_impl(*this, std::forward< F >(f));
|
|
}
|
|
|
|
/// \group map
|
|
/// \synopsis template <class F> constexpr auto map(F &&f) const&&;
|
|
template < class F >
|
|
constexpr auto
|
|
map(F &&f) const &&
|
|
{
|
|
return optional_map_impl(std::move(*this), std::forward< F >(f));
|
|
}
|
|
#else
|
|
/// \brief Carries out some operation on the stored object if there is one.
|
|
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
|
|
/// value())`. Returns a `std::optional<U>`. The return value is empty if
|
|
/// `*this` is empty, otherwise an `optional<U>` is constructed from the
|
|
/// return value of `std::invoke(std::forward<F>(f), value())` and is
|
|
/// returned.
|
|
///
|
|
/// \group map
|
|
/// \synopsis template <class F> auto map(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(*this, std::forward< F >(f));
|
|
}
|
|
|
|
/// \group map
|
|
/// \synopsis template <class F> auto map(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));
|
|
}
|
|
|
|
/// \group map
|
|
/// \synopsis template <class F> auto map(F &&f) const&;
|
|
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
|
|
/// \group map
|
|
/// \synopsis template <class F> auto map(F &&f) const&&;
|
|
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
|
|
|
|
/// \brief Calls `f` if the optional is empty
|
|
/// \requires `std::invoke_result_t<F>` must be void or convertible to
|
|
/// `optional<T>`.
|
|
/// \effects If `*this` has a value, returns `*this`.
|
|
/// Otherwise, if `f` returns `void`, calls `std::forward<F>(f)` and returns
|
|
/// `std::nullopt`. Otherwise, returns `std::forward<F>(f)()`.
|
|
///
|
|
/// \group or_else
|
|
/// \synopsis template <class F> optional<T> or_else (F &&f) &;
|
|
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;
|
|
}
|
|
|
|
/// \exclude
|
|
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)();
|
|
}
|
|
|
|
/// \group or_else
|
|
/// \synopsis template <class F> optional<T> or_else (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;
|
|
}
|
|
|
|
/// \exclude
|
|
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)();
|
|
}
|
|
|
|
/// \group or_else
|
|
/// \synopsis template <class F> optional<T> or_else (F &&f) const &;
|
|
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;
|
|
}
|
|
|
|
/// \exclude
|
|
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
|
|
/// \exclude
|
|
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;
|
|
}
|
|
|
|
/// \exclude
|
|
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
|
|
|
|
/// \brief Maps the stored value with `f` if there is one, otherwise returns
|
|
/// `u`.
|
|
///
|
|
/// \details If there is a value stored, then `f` is called with `**this`
|
|
/// and the value is returned. Otherwise `u` is returned.
|
|
///
|
|
/// \group map_or
|
|
template < 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);
|
|
}
|
|
|
|
/// \group map_or
|
|
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);
|
|
}
|
|
|
|
/// \group map_or
|
|
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
|
|
/// \group map_or
|
|
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
|
|
|
|
/// \brief Maps the stored value with `f` if there is one, otherwise calls
|
|
/// `u` and returns the result.
|
|
///
|
|
/// \details If there is a value stored, then `f` is
|
|
/// called with `**this` and the value is returned. Otherwise
|
|
/// `std::forward<U>(u)()` is returned.
|
|
///
|
|
/// \group map_or_else
|
|
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, 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), **this)
|
|
: std::forward< U >(u)();
|
|
}
|
|
|
|
/// \group map_or_else
|
|
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, 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)();
|
|
}
|
|
|
|
/// \group map_or_else
|
|
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
|
|
/// const &;
|
|
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
|
|
/// \group map_or_else
|
|
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
|
|
/// const &&;
|
|
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.
|
|
/// \group disjunction
|
|
TL_OPTIONAL_11_CONSTEXPR optional
|
|
disjunction(const optional &rhs) &
|
|
{
|
|
return has_value() ? *this : rhs;
|
|
}
|
|
|
|
/// \group disjunction
|
|
constexpr optional
|
|
disjunction(const optional &rhs) const &
|
|
{
|
|
return has_value() ? *this : rhs;
|
|
}
|
|
|
|
/// \group disjunction
|
|
TL_OPTIONAL_11_CONSTEXPR optional
|
|
disjunction(const optional &rhs) &&
|
|
{
|
|
return has_value() ? std::move(*this) : rhs;
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
/// \group disjunction
|
|
constexpr optional
|
|
disjunction(const optional &rhs) const &&
|
|
{
|
|
return has_value() ? std::move(*this) : rhs;
|
|
}
|
|
#endif
|
|
|
|
/// \group disjunction
|
|
TL_OPTIONAL_11_CONSTEXPR optional
|
|
disjunction(optional &&rhs) &
|
|
{
|
|
return has_value() ? *this : std::move(rhs);
|
|
}
|
|
|
|
/// \group disjunction
|
|
constexpr optional
|
|
disjunction(optional &&rhs) const &
|
|
{
|
|
return has_value() ? *this : std::move(rhs);
|
|
}
|
|
|
|
/// \group disjunction
|
|
TL_OPTIONAL_11_CONSTEXPR optional
|
|
disjunction(optional &&rhs) &&
|
|
{
|
|
return has_value() ? std::move(*this) : std::move(rhs);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
/// \group disjunction
|
|
constexpr optional
|
|
disjunction(optional &&rhs) const &&
|
|
{
|
|
return has_value() ? std::move(*this) : std::move(rhs);
|
|
}
|
|
#endif
|
|
|
|
/// Takes the value out of the optional, leaving it empty
|
|
/// \group take
|
|
optional
|
|
take() &
|
|
{
|
|
optional ret = *this;
|
|
reset();
|
|
return ret;
|
|
}
|
|
|
|
/// \group take
|
|
optional
|
|
take() const &
|
|
{
|
|
optional ret = *this;
|
|
reset();
|
|
return ret;
|
|
}
|
|
|
|
/// \group take
|
|
optional
|
|
take() &&
|
|
{
|
|
optional ret = std::move(*this);
|
|
reset();
|
|
return ret;
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
/// \group take
|
|
optional
|
|
take() const &&
|
|
{
|
|
optional ret = std::move(*this);
|
|
reset();
|
|
return ret;
|
|
}
|
|
#endif
|
|
|
|
using value_type = T;
|
|
|
|
/// Constructs an optional that does not contain a value.
|
|
/// \group ctor_empty
|
|
constexpr optional() noexcept = default;
|
|
|
|
/// \group ctor_empty
|
|
constexpr optional(nullopt_t) noexcept
|
|
{
|
|
}
|
|
|
|
/// Copy constructor
|
|
///
|
|
/// If `rhs` contains a value, the stored value is direct-initialized with
|
|
/// it. Otherwise, the constructed optional is empty.
|
|
TL_OPTIONAL_11_CONSTEXPR
|
|
optional(const optional &rhs) = default;
|
|
|
|
/// Move constructor
|
|
///
|
|
/// If `rhs` contains a value, the stored value is direct-initialized with
|
|
/// it. Otherwise, the constructed optional is empty.
|
|
TL_OPTIONAL_11_CONSTEXPR
|
|
optional(optional &&rhs) = default;
|
|
|
|
/// Constructs the stored value in-place using the given arguments.
|
|
/// \group in_place
|
|
/// \synopsis template <class... Args> constexpr explicit
|
|
/// optional(in_place_t, Args&&... args);
|
|
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)...)
|
|
{
|
|
}
|
|
|
|
/// \group in_place
|
|
/// \synopsis template <class U, class... Args>\nconstexpr explicit
|
|
/// optional(in_place_t, std::initializer_list<U>&, 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`.
|
|
/// \synopsis template <class U=T> constexpr optional(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 optional(U &&u) : base(in_place, std::forward< U >(u))
|
|
{
|
|
}
|
|
|
|
/// \exclude
|
|
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.
|
|
/// \synopsis template <class U> optional(const optional<U> &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 >
|
|
optional(const optional< U > &rhs)
|
|
{
|
|
this->construct(*rhs);
|
|
}
|
|
|
|
/// \exclude
|
|
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)
|
|
{
|
|
this->construct(*rhs);
|
|
}
|
|
|
|
/// Converting move constructor.
|
|
/// \synopsis template <class U> optional(optional<U> &&rhs);
|
|
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)
|
|
{
|
|
this->construct(std::move(*rhs));
|
|
}
|
|
|
|
/// \exclude
|
|
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)
|
|
{
|
|
this->construct(std::move(*rhs));
|
|
}
|
|
|
|
/// Destroys the stored value if there is one.
|
|
~optional() = default;
|
|
|
|
/// Assignment to empty.
|
|
///
|
|
/// Destroys the current value if there is one.
|
|
optional &operator=(nullopt_t) noexcept
|
|
{
|
|
if(has_value())
|
|
{
|
|
this->m_value.~T();
|
|
this->m_has_value = false;
|
|
}
|
|
|
|
return *this;
|
|
}
|
|
|
|
/// Copy assignment.
|
|
///
|
|
/// Copies the value from `rhs` if there is one. Otherwise resets the stored
|
|
/// value in `*this`.
|
|
optional &
|
|
operator=(const optional &rhs) = default;
|
|
|
|
/// Move assignment.
|
|
///
|
|
/// Moves the value from `rhs` if there is one. Otherwise resets the stored
|
|
/// value in `*this`.
|
|
optional &
|
|
operator=(optional &&rhs) = default;
|
|
|
|
/// Assigns the stored value from `u`, destroying the old value if there was
|
|
/// one.
|
|
/// \synopsis optional &operator=(U &&u);
|
|
template < 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`.
|
|
/// \synopsis optional &operator=(const optional<U> & rhs);
|
|
template < class U,
|
|
detail::enable_assign_from_other< T, U, const U & > * = nullptr >
|
|
optional &
|
|
operator=(const optional< U > &rhs)
|
|
{
|
|
if(has_value())
|
|
{
|
|
if(rhs.has_value())
|
|
{
|
|
this->m_value = *rhs;
|
|
}
|
|
else
|
|
{
|
|
this->hard_reset();
|
|
}
|
|
}
|
|
|
|
if(rhs.has_value())
|
|
{
|
|
this->construct(*rhs);
|
|
}
|
|
|
|
return *this;
|
|
}
|
|
|
|
// TODO check exception guarantee
|
|
/// Converting move assignment operator.
|
|
///
|
|
/// Moves the value from `rhs` if there is one. Otherwise resets the stored
|
|
/// value in `*this`.
|
|
/// \synopsis optional &operator=(optional<U> && rhs);
|
|
template < class U,
|
|
detail::enable_assign_from_other< T, U, U > * = nullptr >
|
|
optional &
|
|
operator=(optional< U > &&rhs)
|
|
{
|
|
if(has_value())
|
|
{
|
|
if(rhs.has_value())
|
|
{
|
|
this->m_value = std::move(*rhs);
|
|
}
|
|
else
|
|
{
|
|
this->hard_reset();
|
|
}
|
|
}
|
|
|
|
if(rhs.has_value())
|
|
{
|
|
this->construct(std::move(*rhs));
|
|
}
|
|
|
|
return *this;
|
|
}
|
|
|
|
/// Constructs the value in-place, destroying the current one if there is
|
|
/// one.
|
|
/// \group emplace
|
|
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();
|
|
}
|
|
|
|
/// \group emplace
|
|
/// \synopsis template <class U, class... Args>\nT&
|
|
/// emplace(std::initializer_list<U> il, Args &&... args);
|
|
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)
|
|
{
|
|
if(has_value())
|
|
{
|
|
if(rhs.has_value())
|
|
{
|
|
using std::swap;
|
|
swap(**this, *rhs);
|
|
}
|
|
else
|
|
{
|
|
new(std::addressof(rhs.m_value)) T(std::move(this->m_value));
|
|
this->m_value.T::~T();
|
|
}
|
|
}
|
|
else if(rhs.has_value())
|
|
{
|
|
new(std::addressof(this->m_value)) T(std::move(rhs.m_value));
|
|
rhs.m_value.T::~T();
|
|
}
|
|
}
|
|
|
|
/// \returns a pointer to the stored value
|
|
/// \requires a value is stored
|
|
/// \group pointer
|
|
/// \synopsis constexpr const T *operator->() const;
|
|
constexpr const T *operator->() const
|
|
{
|
|
return std::addressof(this->m_value);
|
|
}
|
|
|
|
/// \group pointer
|
|
/// \synopsis constexpr T *operator->();
|
|
TL_OPTIONAL_11_CONSTEXPR T *operator->()
|
|
{
|
|
return std::addressof(this->m_value);
|
|
}
|
|
|
|
/// \returns the stored value
|
|
/// \requires a value is stored
|
|
/// \group deref
|
|
/// \synopsis constexpr T &operator*();
|
|
TL_OPTIONAL_11_CONSTEXPR T &operator*() &
|
|
{
|
|
return this->m_value;
|
|
}
|
|
|
|
/// \group deref
|
|
/// \synopsis constexpr const T &operator*() const;
|
|
constexpr const T &operator*() const &
|
|
{
|
|
return this->m_value;
|
|
}
|
|
|
|
/// \exclude
|
|
TL_OPTIONAL_11_CONSTEXPR T &&operator*() &&
|
|
{
|
|
return std::move(this->m_value);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
/// \exclude
|
|
constexpr const T &&operator*() const &&
|
|
{
|
|
return std::move(this->m_value);
|
|
}
|
|
#endif
|
|
|
|
/// \returns whether or not the optional has a value
|
|
/// \group has_value
|
|
constexpr bool
|
|
has_value() const noexcept
|
|
{
|
|
return this->m_has_value;
|
|
}
|
|
|
|
/// \group has_value
|
|
constexpr explicit operator bool() const noexcept
|
|
{
|
|
return this->m_has_value;
|
|
}
|
|
|
|
/// \returns the contained value if there is one, otherwise throws
|
|
/// [bad_optional_access]
|
|
/// \group value
|
|
/// \synopsis constexpr T &value();
|
|
TL_OPTIONAL_11_CONSTEXPR T &
|
|
value() &
|
|
{
|
|
if(has_value())
|
|
return this->m_value;
|
|
throw bad_optional_access();
|
|
}
|
|
/// \group value
|
|
/// \synopsis constexpr const T &value() const;
|
|
TL_OPTIONAL_11_CONSTEXPR const T &
|
|
value() const &
|
|
{
|
|
if(has_value())
|
|
return this->m_value;
|
|
throw bad_optional_access();
|
|
}
|
|
/// \exclude
|
|
TL_OPTIONAL_11_CONSTEXPR T &&
|
|
value() &&
|
|
{
|
|
if(has_value())
|
|
return std::move(this->m_value);
|
|
throw bad_optional_access();
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
/// \exclude
|
|
TL_OPTIONAL_11_CONSTEXPR const T &&
|
|
value() const &&
|
|
{
|
|
if(has_value())
|
|
return std::move(this->m_value);
|
|
throw bad_optional_access();
|
|
}
|
|
#endif
|
|
|
|
/// \returns the stored value if there is one, otherwise returns `u`
|
|
/// \group value_or
|
|
template < 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));
|
|
}
|
|
|
|
/// \group value_or
|
|
template < class U >
|
|
TL_OPTIONAL_11_CONSTEXPR T
|
|
value_or(U &&u) &&
|
|
{
|
|
static_assert(std::is_move_constructible< T >::value
|
|
&& std::is_convertible< U &&, T >::value,
|
|
"T must be move constructible and convertible from U");
|
|
return has_value() ? **this : static_cast< T >(std::forward< U >(u));
|
|
}
|
|
|
|
/// Destroys the stored value if one exists, making the optional empty
|
|
void
|
|
reset() noexcept
|
|
{
|
|
if(has_value())
|
|
{
|
|
this->m_value.~T();
|
|
this->m_has_value = false;
|
|
}
|
|
}
|
|
}; // namespace tl
|
|
|
|
/// \group relop
|
|
/// \brief Compares two optional objects
|
|
/// \details If both optionals contain a value, they are compared with `T`s
|
|
/// relational operators. Otherwise `lhs` and `rhs` are equal only if they are
|
|
/// both empty, and `lhs` is less than `rhs` only if `rhs` is empty and `lhs`
|
|
/// is not.
|
|
template < 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);
|
|
}
|
|
/// \group relop
|
|
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);
|
|
}
|
|
/// \group relop
|
|
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);
|
|
}
|
|
/// \group relop
|
|
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);
|
|
}
|
|
/// \group relop
|
|
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);
|
|
}
|
|
/// \group relop
|
|
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);
|
|
}
|
|
|
|
/// \group relop_nullopt
|
|
/// \brief Compares an optional to a `nullopt`
|
|
/// \details Equivalent to comparing the optional to an empty optional
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator==(const optional< T > &lhs, nullopt_t) noexcept
|
|
{
|
|
return !lhs.has_value();
|
|
}
|
|
/// \group relop_nullopt
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator==(nullopt_t, const optional< T > &rhs) noexcept
|
|
{
|
|
return !rhs.has_value();
|
|
}
|
|
/// \group relop_nullopt
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator!=(const optional< T > &lhs, nullopt_t) noexcept
|
|
{
|
|
return lhs.has_value();
|
|
}
|
|
/// \group relop_nullopt
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator!=(nullopt_t, const optional< T > &rhs) noexcept
|
|
{
|
|
return rhs.has_value();
|
|
}
|
|
/// \group relop_nullopt
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator<(const optional< T > &, nullopt_t) noexcept
|
|
{
|
|
return false;
|
|
}
|
|
/// \group relop_nullopt
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator<(nullopt_t, const optional< T > &rhs) noexcept
|
|
{
|
|
return rhs.has_value();
|
|
}
|
|
/// \group relop_nullopt
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator<=(const optional< T > &lhs, nullopt_t) noexcept
|
|
{
|
|
return !lhs.has_value();
|
|
}
|
|
/// \group relop_nullopt
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator<=(nullopt_t, const optional< T > &) noexcept
|
|
{
|
|
return true;
|
|
}
|
|
/// \group relop_nullopt
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator>(const optional< T > &lhs, nullopt_t) noexcept
|
|
{
|
|
return lhs.has_value();
|
|
}
|
|
/// \group relop_nullopt
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator>(nullopt_t, const optional< T > &) noexcept
|
|
{
|
|
return false;
|
|
}
|
|
/// \group relop_nullopt
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator>=(const optional< T > &, nullopt_t) noexcept
|
|
{
|
|
return true;
|
|
}
|
|
/// \group relop_nullopt
|
|
template < class T >
|
|
inline constexpr bool
|
|
operator>=(nullopt_t, const optional< T > &rhs) noexcept
|
|
{
|
|
return !rhs.has_value();
|
|
}
|
|
|
|
/// \group relop_t
|
|
/// \brief Compares the optional with a value.
|
|
/// \details If the optional has a value, it is compared with the other value
|
|
/// using `T`s relational operators. Otherwise, the optional is considered
|
|
/// less than the value.
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator==(const optional< T > &lhs, const U &rhs)
|
|
{
|
|
return lhs.has_value() ? *lhs == rhs : false;
|
|
}
|
|
/// \group relop_t
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator==(const U &lhs, const optional< T > &rhs)
|
|
{
|
|
return rhs.has_value() ? lhs == *rhs : false;
|
|
}
|
|
/// \group relop_t
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator!=(const optional< T > &lhs, const U &rhs)
|
|
{
|
|
return lhs.has_value() ? *lhs != rhs : true;
|
|
}
|
|
/// \group relop_t
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator!=(const U &lhs, const optional< T > &rhs)
|
|
{
|
|
return rhs.has_value() ? lhs != *rhs : true;
|
|
}
|
|
/// \group relop_t
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator<(const optional< T > &lhs, const U &rhs)
|
|
{
|
|
return lhs.has_value() ? *lhs < rhs : true;
|
|
}
|
|
/// \group relop_t
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator<(const U &lhs, const optional< T > &rhs)
|
|
{
|
|
return rhs.has_value() ? lhs < *rhs : false;
|
|
}
|
|
/// \group relop_t
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator<=(const optional< T > &lhs, const U &rhs)
|
|
{
|
|
return lhs.has_value() ? *lhs <= rhs : true;
|
|
}
|
|
/// \group relop_t
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator<=(const U &lhs, const optional< T > &rhs)
|
|
{
|
|
return rhs.has_value() ? lhs <= *rhs : false;
|
|
}
|
|
/// \group relop_t
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator>(const optional< T > &lhs, const U &rhs)
|
|
{
|
|
return lhs.has_value() ? *lhs > rhs : false;
|
|
}
|
|
/// \group relop_t
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator>(const U &lhs, const optional< T > &rhs)
|
|
{
|
|
return rhs.has_value() ? lhs > *rhs : true;
|
|
}
|
|
/// \group relop_t
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator>=(const optional< T > &lhs, const U &rhs)
|
|
{
|
|
return lhs.has_value() ? *lhs >= rhs : false;
|
|
}
|
|
/// \group relop_t
|
|
template < class T, class U >
|
|
inline constexpr bool
|
|
operator>=(const U &lhs, const optional< T > &rhs)
|
|
{
|
|
return rhs.has_value() ? lhs >= *rhs : true;
|
|
}
|
|
|
|
/// \synopsis template <class T>\nvoid swap(optional<T> &lhs, optional<T>
|
|
/// &rhs);
|
|
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.
|
|
///
|
|
/// *Examples*:
|
|
///
|
|
/// ```
|
|
/// int i = 42;
|
|
/// tl::optional<int&> o = i;
|
|
/// *o == 42; //true
|
|
/// i = 12;
|
|
/// *o = 12; //true
|
|
/// &*o == &i; //true
|
|
/// ```
|
|
///
|
|
/// Assignment has rebind semantics rather than assign-through semantics:
|
|
///
|
|
/// ```
|
|
/// int j = 8;
|
|
/// o = j;
|
|
///
|
|
/// &*o == &j; //true
|
|
/// ```
|
|
template < class 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)
|
|
/// \group and_then
|
|
/// Carries out some operation which returns an optional on the stored
|
|
/// object if there is one. \requires `std::invoke(std::forward<F>(f),
|
|
/// value())` returns a `std::optional<U>` for some `U`. \returns Let `U` be
|
|
/// the result of `std::invoke(std::forward<F>(f), value())`. Returns a
|
|
/// `std::optional<U>`. The return value is empty if `*this` is empty,
|
|
/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
|
|
/// is returned.
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
|
|
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);
|
|
}
|
|
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
|
|
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);
|
|
}
|
|
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &;
|
|
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
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
|
|
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
|
|
/// \group and_then
|
|
/// Carries out some operation which returns an optional on the stored
|
|
/// object if there is one. \requires `std::invoke(std::forward<F>(f),
|
|
/// value())` returns a `std::optional<U>` for some `U`. \returns Let `U` be
|
|
/// the result of `std::invoke(std::forward<F>(f), value())`. Returns a
|
|
/// `std::optional<U>`. The return value is empty if `*this` is empty,
|
|
/// otherwise the return value of `std::invoke(std::forward<F>(f), value())`
|
|
/// is returned.
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &;
|
|
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);
|
|
}
|
|
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) &&;
|
|
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);
|
|
}
|
|
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &;
|
|
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
|
|
/// \group and_then
|
|
/// \synopsis template <class F>\nconstexpr auto and_then(F &&f) const &&;
|
|
template < class F >
|
|
constexpr detail::invoke_result_t< F, const T & >
|
|
and_then(F &&f) const &&
|
|
{
|
|
using result = detail::invoke_result_t< F, const T & >;
|
|
static_assert(detail::is_optional< result >::value,
|
|
"F must return an optional");
|
|
|
|
return has_value() ? detail::invoke(std::forward< F >(f), **this)
|
|
: result(nullopt);
|
|
}
|
|
#endif
|
|
#endif
|
|
|
|
#if defined(TL_OPTIONAL_CXX14) && !defined(TL_OPTIONAL_GCC49) \
|
|
&& !defined(TL_OPTIONAL_GCC54) && !defined(TL_OPTIONAL_GCC55)
|
|
/// \brief Carries out some operation on the stored object if there is one.
|
|
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
|
|
/// value())`. Returns a `std::optional<U>`. The return value is empty if
|
|
/// `*this` is empty, otherwise an `optional<U>` is constructed from the
|
|
/// return value of `std::invoke(std::forward<F>(f), value())` and is
|
|
/// returned.
|
|
///
|
|
/// \group map
|
|
/// \synopsis template <class F> constexpr auto map(F &&f) &;
|
|
template < class F >
|
|
TL_OPTIONAL_11_CONSTEXPR auto
|
|
map(F &&f) &
|
|
{
|
|
return detail::optional_map_impl(*this, std::forward< F >(f));
|
|
}
|
|
|
|
/// \group map
|
|
/// \synopsis template <class F> constexpr auto map(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));
|
|
}
|
|
|
|
/// \group map
|
|
/// \synopsis template <class F> constexpr auto map(F &&f) const&;
|
|
template < class F >
|
|
constexpr auto
|
|
map(F &&f) const &
|
|
{
|
|
return detail::optional_map_impl(*this, std::forward< F >(f));
|
|
}
|
|
|
|
/// \group map
|
|
/// \synopsis template <class F> constexpr auto map(F &&f) const&&;
|
|
template < class F >
|
|
constexpr auto
|
|
map(F &&f) const &&
|
|
{
|
|
return detail::optional_map_impl(std::move(*this), std::forward< F >(f));
|
|
}
|
|
#else
|
|
/// \brief Carries out some operation on the stored object if there is one.
|
|
/// \returns Let `U` be the result of `std::invoke(std::forward<F>(f),
|
|
/// value())`. Returns a `std::optional<U>`. The return value is empty if
|
|
/// `*this` is empty, otherwise an `optional<U>` is constructed from the
|
|
/// return value of `std::invoke(std::forward<F>(f), value())` and is
|
|
/// returned.
|
|
///
|
|
/// \group map
|
|
/// \synopsis template <class F> auto map(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(*this, std::forward< F >(f));
|
|
}
|
|
|
|
/// \group map
|
|
/// \synopsis template <class F> auto map(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));
|
|
}
|
|
|
|
/// \group map
|
|
/// \synopsis template <class F> auto map(F &&f) const&;
|
|
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
|
|
/// \group map
|
|
/// \synopsis template <class F> auto map(F &&f) const&&;
|
|
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
|
|
|
|
/// \brief Calls `f` if the optional is empty
|
|
/// \requires `std::invoke_result_t<F>` must be void or convertible to
|
|
/// `optional<T>`. \effects If `*this` has a value, returns `*this`.
|
|
/// Otherwise, if `f` returns `void`, calls `std::forward<F>(f)` and returns
|
|
/// `std::nullopt`. Otherwise, returns `std::forward<F>(f)()`.
|
|
///
|
|
/// \group or_else
|
|
/// \synopsis template <class F> optional<T> or_else (F &&f) &;
|
|
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;
|
|
}
|
|
|
|
/// \exclude
|
|
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)();
|
|
}
|
|
|
|
/// \group or_else
|
|
/// \synopsis template <class F> optional<T> or_else (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;
|
|
}
|
|
|
|
/// \exclude
|
|
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)();
|
|
}
|
|
|
|
/// \group or_else
|
|
/// \synopsis template <class F> optional<T> or_else (F &&f) const &;
|
|
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;
|
|
}
|
|
|
|
/// \exclude
|
|
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
|
|
/// \exclude
|
|
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;
|
|
}
|
|
|
|
/// \exclude
|
|
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
|
|
|
|
/// \brief Maps the stored value with `f` if there is one, otherwise returns
|
|
/// `u`.
|
|
///
|
|
/// \details If there is a value stored, then `f` is called with `**this`
|
|
/// and the value is returned. Otherwise `u` is returned.
|
|
///
|
|
/// \group map_or
|
|
template < 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);
|
|
}
|
|
|
|
/// \group map_or
|
|
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);
|
|
}
|
|
|
|
/// \group map_or
|
|
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
|
|
/// \group map_or
|
|
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
|
|
|
|
/// \brief Maps the stored value with `f` if there is one, otherwise calls
|
|
/// `u` and returns the result.
|
|
///
|
|
/// \details If there is a value stored, then `f` is
|
|
/// called with `**this` and the value is returned. Otherwise
|
|
/// `std::forward<U>(u)()` is returned.
|
|
///
|
|
/// \group map_or_else
|
|
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, 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), **this)
|
|
: std::forward< U >(u)();
|
|
}
|
|
|
|
/// \group map_or_else
|
|
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, 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)();
|
|
}
|
|
|
|
/// \group map_or_else
|
|
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
|
|
/// const &;
|
|
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
|
|
/// \group map_or_else
|
|
/// \synopsis template <class F, class U>\nauto map_or_else(F &&f, U &&u)
|
|
/// const &&;
|
|
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.
|
|
/// \group disjunction
|
|
TL_OPTIONAL_11_CONSTEXPR optional
|
|
disjunction(const optional &rhs) &
|
|
{
|
|
return has_value() ? *this : rhs;
|
|
}
|
|
|
|
/// \group disjunction
|
|
constexpr optional
|
|
disjunction(const optional &rhs) const &
|
|
{
|
|
return has_value() ? *this : rhs;
|
|
}
|
|
|
|
/// \group disjunction
|
|
TL_OPTIONAL_11_CONSTEXPR optional
|
|
disjunction(const optional &rhs) &&
|
|
{
|
|
return has_value() ? std::move(*this) : rhs;
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
/// \group disjunction
|
|
constexpr optional
|
|
disjunction(const optional &rhs) const &&
|
|
{
|
|
return has_value() ? std::move(*this) : rhs;
|
|
}
|
|
#endif
|
|
|
|
/// \group disjunction
|
|
TL_OPTIONAL_11_CONSTEXPR optional
|
|
disjunction(optional &&rhs) &
|
|
{
|
|
return has_value() ? *this : std::move(rhs);
|
|
}
|
|
|
|
/// \group disjunction
|
|
constexpr optional
|
|
disjunction(optional &&rhs) const &
|
|
{
|
|
return has_value() ? *this : std::move(rhs);
|
|
}
|
|
|
|
/// \group disjunction
|
|
TL_OPTIONAL_11_CONSTEXPR optional
|
|
disjunction(optional &&rhs) &&
|
|
{
|
|
return has_value() ? std::move(*this) : std::move(rhs);
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
/// \group disjunction
|
|
constexpr optional
|
|
disjunction(optional &&rhs) const &&
|
|
{
|
|
return has_value() ? std::move(*this) : std::move(rhs);
|
|
}
|
|
#endif
|
|
|
|
/// Takes the value out of the optional, leaving it empty
|
|
/// \group take
|
|
optional
|
|
take() &
|
|
{
|
|
optional ret = *this;
|
|
reset();
|
|
return ret;
|
|
}
|
|
|
|
/// \group take
|
|
optional
|
|
take() const &
|
|
{
|
|
optional ret = *this;
|
|
reset();
|
|
return ret;
|
|
}
|
|
|
|
/// \group take
|
|
optional
|
|
take() &&
|
|
{
|
|
optional ret = std::move(*this);
|
|
reset();
|
|
return ret;
|
|
}
|
|
|
|
#ifndef TL_OPTIONAL_NO_CONSTRR
|
|
/// \group take
|
|
optional
|
|
take() const &&
|
|
{
|
|
optional ret = std::move(*this);
|
|
reset();
|
|
return ret;
|
|
}
|
|
#endif
|
|
|
|
using value_type = T &;
|
|
|
|
/// Constructs an optional that does not contain a value.
|
|
/// \group ctor_empty
|
|
constexpr optional() noexcept : m_value(nullptr)
|
|
{
|
|
}
|
|
|
|
/// \group ctor_empty
|
|
constexpr optional(nullopt_t) noexcept : m_value(nullptr)
|
|
{
|
|
}
|
|
|
|
/// Copy constructor
|
|
///
|
|
/// If `rhs` contains a value, the stored value is direct-initialized with
|
|
/// it. Otherwise, the constructed optional is empty.
|
|
TL_OPTIONAL_11_CONSTEXPR
|
|
optional(const optional &rhs) noexcept = default;
|
|
|
|
/// Move constructor
|
|
///
|
|
/// If `rhs` contains a value, the stored value is direct-initialized with
|
|
/// it. Otherwise, the constructed optional is empty.
|
|
TL_OPTIONAL_11_CONSTEXPR
|
|
optional(optional &&rhs) = default;
|
|
|
|
/// Constructs the stored value with `u`.
|
|
/// \synopsis template <class U=T> constexpr optional(U &&u);
|
|
template < class U = T,
|
|
detail::enable_if_t< !detail::is_optional<
|
|
detail::decay_t< U > >::value > * = nullptr >
|
|
constexpr optional(U &&u) : m_value(std::addressof(u))
|
|
{
|
|
static_assert(std::is_lvalue_reference< U >::value,
|
|
"U must be an lvalue");
|
|
}
|
|
|
|
/// \exclude
|
|
template < class U >
|
|
constexpr explicit optional(const optional< U > &rhs) : optional(*rhs)
|
|
{
|
|
}
|
|
|
|
/// No-op
|
|
~optional() = default;
|
|
|
|
/// Assignment to empty.
|
|
///
|
|
/// Destroys the current value if there is one.
|
|
optional &operator=(nullopt_t) noexcept
|
|
{
|
|
m_value = nullptr;
|
|
return *this;
|
|
}
|
|
|
|
/// Copy assignment.
|
|
///
|
|
/// Rebinds this optional to the referee of `rhs` if there is one. Otherwise
|
|
/// resets the stored value in `*this`.
|
|
optional &
|
|
operator=(const optional &rhs) = default;
|
|
|
|
/// Rebinds this optional to `u`.
|
|
///
|
|
/// \requires `U` must be an lvalue reference.
|
|
/// \synopsis optional &operator=(U &&u);
|
|
template < 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)
|
|
{
|
|
m_value = std::addressof(rhs.value());
|
|
return *this;
|
|
}
|
|
|
|
/// Constructs the value in-place, destroying the current one if there is
|
|
/// one.
|
|
///
|
|
/// \group emplace
|
|
template < class... Args >
|
|
T &
|
|
emplace(Args &&... args) noexcept
|
|
{
|
|
static_assert(std::is_constructible< T, Args &&... >::value,
|
|
"T must be constructible with Args");
|
|
|
|
*this = nullopt;
|
|
this->construct(std::forward< Args >(args)...);
|
|
}
|
|
|
|
/// Swaps this optional with the other.
|
|
///
|
|
/// If neither optionals have a value, nothing happens.
|
|
/// If both have a value, the values are swapped.
|
|
/// If one has a value, it is moved to the other and the movee is left
|
|
/// valueless.
|
|
void
|
|
swap(optional &rhs) noexcept
|
|
{
|
|
std::swap(m_value, rhs.m_value);
|
|
}
|
|
|
|
/// \returns a pointer to the stored value
|
|
/// \requires a value is stored
|
|
/// \group pointer
|
|
/// \synopsis constexpr const T *operator->() const;
|
|
constexpr const T *operator->() const
|
|
{
|
|
return m_value;
|
|
}
|
|
|
|
/// \group pointer
|
|
/// \synopsis constexpr T *operator->();
|
|
TL_OPTIONAL_11_CONSTEXPR T *operator->()
|
|
{
|
|
return m_value;
|
|
}
|
|
|
|
/// \returns the stored value
|
|
/// \requires a value is stored
|
|
/// \group deref
|
|
/// \synopsis constexpr T &operator*();
|
|
TL_OPTIONAL_11_CONSTEXPR T &operator*()
|
|
{
|
|
return *m_value;
|
|
}
|
|
|
|
/// \group deref
|
|
/// \synopsis constexpr const T &operator*() const;
|
|
constexpr const T &operator*() const
|
|
{
|
|
return *m_value;
|
|
}
|
|
|
|
/// \returns whether or not the optional has a value
|
|
/// \group has_value
|
|
constexpr bool
|
|
has_value() const noexcept
|
|
{
|
|
return m_value != nullptr;
|
|
}
|
|
|
|
/// \group has_value
|
|
constexpr explicit operator bool() const noexcept
|
|
{
|
|
return m_value != nullptr;
|
|
}
|
|
|
|
/// \returns the contained value if there is one, otherwise throws
|
|
/// [bad_optional_access]
|
|
/// \group value
|
|
/// synopsis constexpr T &value();
|
|
TL_OPTIONAL_11_CONSTEXPR T &
|
|
value()
|
|
{
|
|
if(has_value())
|
|
return *m_value;
|
|
throw bad_optional_access();
|
|
}
|
|
/// \group value
|
|
/// \synopsis constexpr const T &value() const;
|
|
TL_OPTIONAL_11_CONSTEXPR const T &
|
|
value() const
|
|
{
|
|
if(has_value())
|
|
return *m_value;
|
|
throw bad_optional_access();
|
|
}
|
|
|
|
/// \returns the stored value if there is one, otherwise returns `u`
|
|
/// \group value_or
|
|
template < 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));
|
|
}
|
|
|
|
/// \group value_or
|
|
template < class U >
|
|
TL_OPTIONAL_11_CONSTEXPR T
|
|
value_or(U &&u) &&
|
|
{
|
|
static_assert(std::is_move_constructible< T >::value
|
|
&& std::is_convertible< U &&, T >::value,
|
|
"T must be move constructible and convertible from U");
|
|
return has_value() ? **this : static_cast< T >(std::forward< U >(u));
|
|
}
|
|
|
|
/// Destroys the stored value if one exists, making the optional empty
|
|
void
|
|
reset() noexcept
|
|
{
|
|
m_value = nullptr;
|
|
}
|
|
|
|
private:
|
|
T *m_value;
|
|
}; // namespace tl
|
|
|
|
} // namespace tl
|
|
|
|
namespace std
|
|
{
|
|
// TODO SFINAE
|
|
template < class T >
|
|
struct hash< tl::optional< T > >
|
|
{
|
|
::std::size_t
|
|
operator()(const tl::optional< T > &o) const
|
|
{
|
|
if(!o.has_value())
|
|
return 0;
|
|
|
|
return std::hash< tl::detail::remove_const_t< T > >()(*o);
|
|
}
|
|
};
|
|
} // namespace std
|
|
|
|
#endif
|