diff options
Diffstat (limited to 'libstdc++-v3/include/bits/indirect.h')
| -rw-r--r-- | libstdc++-v3/include/bits/indirect.h | 376 |
1 files changed, 375 insertions, 1 deletions
diff --git a/libstdc++-v3/include/bits/indirect.h b/libstdc++-v3/include/bits/indirect.h index 85908e2..e8000d7 100644 --- a/libstdc++-v3/include/bits/indirect.h +++ b/libstdc++-v3/include/bits/indirect.h @@ -452,7 +452,381 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { }; #endif // __glibcxx_indirect - _GLIBCXX_END_NAMESPACE_VERSION +#if __glibcxx_polymorphic // C++26 && HOSTED + template<typename _Tp, typename _Alloc = allocator<_Tp>> + class polymorphic; + + namespace pmr + { + template<typename _Tp> + using polymorphic = polymorphic<_Tp, polymorphic_allocator<_Tp>>; + } + + // [polymorphic], class template polymorphic + template<typename _Tp, typename _Alloc> + class polymorphic + { + static_assert(is_object_v<_Tp>); + static_assert(!is_array_v<_Tp>); + static_assert(!is_same_v<_Tp, in_place_t>); + static_assert(!__is_in_place_type_v<_Tp>); + static_assert(!is_const_v<_Tp> && !is_volatile_v<_Tp>); + + using _ATraits = allocator_traits<_Alloc>; + static_assert(is_same_v<_Tp, typename _ATraits::value_type>); + + // The owned object is embedded within a control block which knows the + // dynamic type and manages cloning and destroying the owned object. + struct _Obj + { + typename _ATraits::pointer _M_objp{}; // pointer to the owned object. + + // A pointer to this type, e.g. _Obj* + using pointer + = typename _ATraits::template rebind_traits<_Obj>::pointer; + + enum class _Op { _Dispose = 1, _Copy = 2, _Move = 3 }; + + constexpr virtual pointer + _M_manage(const _Alloc&, _Op, void* = nullptr) = 0; + }; + + template<typename _Up> + struct _Obj_impl : _Obj + { + using _MyTraits + = typename _ATraits::template rebind_traits<_Obj_impl>; + + using _Op = _Obj::_Op; + + union _Uninitialized { + constexpr _Uninitialized() { } + constexpr ~_Uninitialized() { } + _Up _M_objp; + }; + _Uninitialized _M_u; + + template<typename... _Args> + constexpr + _Obj_impl(typename _MyTraits::allocator_type& __a, + _Args&&... __args) + { + using _PtrTr = pointer_traits<typename _ATraits::pointer>; + _MyTraits::construct(__a, __builtin_addressof(_M_u._M_objp), + std::forward<_Args>(__args)...); + this->_M_objp = _PtrTr::pointer_to(_M_u._M_objp); + } + + constexpr virtual typename _Obj::pointer + _M_manage(const _Alloc& __a, _Op __op, void*) override + { + + switch (__op) + { + case _Op::_Move: + return _S_make_obj<_Up>(__a, std::move(_M_u._M_objp)); + case _Op::_Copy: + return _S_make_obj<_Up>(__a, + const_cast<const _Up&>(_M_u._M_objp)); + case _Op::_Dispose: + { + using _PtrTr = pointer_traits<typename _MyTraits::pointer>; + typename _MyTraits::allocator_type __a2(__a); + _MyTraits::destroy(__a2, std::__addressof(_M_u._M_objp)); + _MyTraits::deallocate(__a2, _PtrTr::pointer_to(*this), 1); + return nullptr; + } + } + __builtin_unreachable(); + } + }; + + // TODO: the standard permits a small-object optimization where the + // owned object is nested within the std::polymorphic not on the heap. + + public: + + using value_type = _Tp; + using allocator_type = _Alloc; + using pointer = typename allocator_traits<_Alloc>::pointer; + using const_pointer = typename allocator_traits<_Alloc>::const_pointer; + + constexpr explicit + polymorphic() requires is_default_constructible_v<_Alloc> + : polymorphic(in_place_type<_Tp>) + { } + + constexpr explicit + polymorphic(allocator_arg_t, const _Alloc& __a) + : polymorphic(allocator_arg, __a, in_place_type<_Tp>) + { } + + constexpr + polymorphic(const polymorphic& __other) + : polymorphic(allocator_arg, + _ATraits::select_on_container_copy_construction( + __other._M_alloc), + __other) + { } + + constexpr + polymorphic(allocator_arg_t, const _Alloc& __a, + const polymorphic& __other) + : _M_alloc(__a) + { + if (__other._M_objp) + _M_objp = __other._M_objp->_M_manage(__a, _Obj::_Op::_Copy); + else + _M_objp = nullptr; + } + + constexpr + polymorphic(polymorphic&& __other) noexcept + : _M_alloc(std::move(__other._M_alloc)), + _M_objp(std::__exchange(__other._M_objp, nullptr)) + { } + + constexpr + polymorphic(allocator_arg_t, const _Alloc& __a, polymorphic&& __other) + noexcept(_ATraits::is_always_equal::value) + : _M_alloc(__a), + _M_objp(std::__exchange(__other._M_objp, nullptr)) + { + if constexpr (!_ATraits::is_always_equal::value) + if (_M_objp && _M_alloc != __other._M_alloc) + { + // _M_alloc cannot free _M_objp, give it back to __other. + __other._M_objp = std::__exchange(_M_objp, nullptr); + // And create a new object that can be freed by _M_alloc. + _M_objp = __other._M_objp->_M_manage(__a, _Obj::_Op::_Move); + } + } + + template<typename _Up = _Tp, typename _UUp = remove_cvref_t<_Up>> + requires (!is_same_v<_UUp, polymorphic>) + && (!__is_in_place_type_v<_UUp>) + && derived_from<_UUp, _Tp> + && is_constructible_v<_UUp, _Up> + && is_copy_constructible_v<_UUp> + && is_default_constructible_v<_Alloc> + constexpr explicit + polymorphic(_Up&& __u) + : _M_objp(_M_make_obj<_UUp>(std::forward<_Up>(__u))) + { } + + template<typename _Up = _Tp, typename _UUp = remove_cvref_t<_Up>> + requires (!is_same_v<_UUp, polymorphic>) + && (!__is_in_place_type_v<_UUp>) + && derived_from<_UUp, _Tp> + && is_constructible_v<_UUp, _Up> + && is_copy_constructible_v<_UUp> + constexpr explicit + polymorphic(allocator_arg_t, const _Alloc& __a, _Up&& __u) + : _M_alloc(__a), _M_objp(_M_make_obj<_UUp>(std::forward<_Up>(__u))) + { } + + template<typename _Up, typename... _Ts> + requires is_same_v<remove_cvref_t<_Up>, _Up> + && derived_from<_Up, _Tp> + && is_constructible_v<_Up, _Ts...> + && is_copy_constructible_v<_Up> + && is_default_constructible_v<_Alloc> + constexpr explicit + polymorphic(in_place_type_t<_Up> __t, _Ts&&... __ts) + : _M_objp(_M_make_obj<_Up>(std::forward<_Ts>(__ts)...)) + { } + + template<typename _Up, typename... _Ts> + requires is_same_v<remove_cvref_t<_Up>, _Up> + && derived_from<_Up, _Tp> + && is_constructible_v<_Up, _Ts...> + && is_copy_constructible_v<_Up> + constexpr explicit + polymorphic(allocator_arg_t, const _Alloc& __a, + in_place_type_t<_Up>, _Ts&&... __ts) + : _M_alloc(__a), + _M_objp(_M_make_obj<_Up>(std::forward<_Ts>(__ts)...)) + { } + + template<typename _Up, typename _Ip, typename... _Us> + requires is_same_v<remove_cvref_t<_Up>, _Up> + && derived_from<_Up, _Tp> + && is_constructible_v<_Up, initializer_list<_Ip>&, _Us...> + && is_copy_constructible_v<_Up> + && is_default_constructible_v<_Alloc> + constexpr explicit + polymorphic(in_place_type_t<_Up>, initializer_list<_Ip> __il, + _Us&&... __us) + : _M_objp(_M_make_obj<_Up>(__il, std::forward<_Us>(__us)...)) + { } + + template<typename _Up, typename _Ip, typename... _Us> + requires is_same_v<remove_cvref_t<_Up>, _Up> + && derived_from<_Up, _Tp> + && is_constructible_v<_Up, initializer_list<_Ip>&, _Us...> + && is_copy_constructible_v<_Up> + constexpr explicit + polymorphic(allocator_arg_t, const _Alloc& __a, + in_place_type_t<_Up>, initializer_list<_Ip> __il, + _Us&&... __us) + : _M_alloc(__a), + _M_objp(_M_make_obj<_Up>(__il, std::forward<_Us>(__us)...)) + { } + + constexpr ~polymorphic() + { + static_assert(sizeof(_Tp) != 0, "must be a complete type"); + _M_reset(nullptr); + } + + constexpr polymorphic& + operator=(const polymorphic& __other) + { + static_assert(sizeof(_Tp) != 0, "must be a complete type"); + + if (__builtin_addressof(__other) == this) [[unlikely]] + return *this; + + constexpr bool __pocca + = _ATraits::propagate_on_container_copy_assignment::value; + + typename _Obj::pointer __ptr = nullptr; + if (__other._M_objp) + { + auto& __a = __pocca ? __other._M_alloc : _M_alloc; + __ptr = __other._M_objp->_M_manage(__a, _Obj::_Op::_Copy); + } + + _M_reset(__ptr); + + if constexpr (__pocca) + _M_alloc = __other._M_alloc; + + return *this; + } + + constexpr polymorphic& + operator=(polymorphic&& __other) + noexcept(_ATraits::propagate_on_container_move_assignment::value + || _ATraits::is_always_equal::value) + { + if (__builtin_addressof(__other) == this) [[unlikely]] + return *this; + + constexpr bool __pocma + = _ATraits::propagate_on_container_move_assignment::value; + + typename _Obj::pointer __ptr = nullptr; + + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 4251. Move assignment for indirect unnecessarily requires copy construction + if constexpr (_ATraits::is_always_equal::value || __pocma) + __ptr = std::__exchange(__other._M_objp, nullptr); + else if (_M_alloc == __other._M_alloc) + __ptr = std::__exchange(__other._M_objp, nullptr); + else if (__other._M_objp) + { + static_assert(sizeof(_Tp) != 0, "must be a complete type"); + __ptr = __other._M_objp->_M_manage(_M_alloc, _Obj::_Op::_Move); + } + + _M_reset(__ptr); + + if constexpr (__pocma) + _M_alloc = __other._M_alloc; + + return *this; + } + + constexpr const _Tp& + operator*() const noexcept + { + __glibcxx_assert(_M_objp != nullptr); + return *_M_objp->_M_objp; + } + + constexpr _Tp& + operator*() noexcept + { + __glibcxx_assert(_M_objp != nullptr); + return *_M_objp->_M_objp; + } + + constexpr const_pointer + operator->() const noexcept + { + __glibcxx_assert(_M_objp != nullptr); + return _M_objp ? _M_objp->_M_objp : const_pointer{}; + } + + constexpr pointer + operator->() noexcept + { + __glibcxx_assert(_M_objp != nullptr); + return _M_objp ? _M_objp->_M_objp : pointer{}; + } + + constexpr bool + valueless_after_move() const noexcept { return _M_objp == nullptr; } + + constexpr allocator_type + get_allocator() const noexcept { return _M_alloc; } + + constexpr void + swap(polymorphic& __other) + noexcept(_ATraits::propagate_on_container_swap::value + || _ATraits::is_always_equal::value) + { + using std::swap; + swap(_M_objp, __other._M_objp); + if constexpr (_ATraits::propagate_on_container_swap::value) + swap(_M_alloc, __other._M_alloc); + else if constexpr (!_ATraits::is_always_equal::value) + __glibcxx_assert(_M_alloc == __other._M_alloc); + } + + friend constexpr void + swap(polymorphic& __lhs, polymorphic& __rhs) + noexcept(_ATraits::propagate_on_container_swap::value + || _ATraits::is_always_equal::value) + { __lhs.swap(__rhs); } + + private: + template<typename _Up, typename... _Args> + static constexpr typename _Obj::pointer + _S_make_obj(const _Alloc& __a, _Args&&... __args) + { + __alloc_rebind<_Alloc, _Obj_impl<_Up>> __objalloc(__a); + _Scoped_allocation __sa(__objalloc, in_place, __objalloc, + std::forward<_Args>(__args)...); + auto __obj = __sa.release(); + // FIXME: We need to downcast from _Obj_impl<U>* to _Obj* but the + // the pointer_traits usage breaks in constexpr. PR c++/110714 + if constexpr (is_pointer_v<typename _Obj::pointer>) + return __obj; + else + return pointer_traits<typename _Obj::pointer>::pointer_to(*__obj); + } + + template<typename _Up, typename... _Args> + constexpr typename _Obj::pointer + _M_make_obj(_Args&&... __args) const + { return _S_make_obj<_Up>(_M_alloc, std::forward<_Args>(__args)...); } + + constexpr void + _M_reset(typename _Obj::pointer __ptr) noexcept + { + if (_M_objp) + _M_objp->_M_manage(_M_alloc, _Obj::_Op::_Dispose); + _M_objp = __ptr; + } + + [[no_unique_address]] _Alloc _M_alloc = _Alloc(); + typename _Obj::pointer _M_objp; + }; +#endif // __glibcxx_polymorphic + +_GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif // C++26 __glibcxx_indirect || __glibcxx_polymorphic |