322 lines
10 KiB
C++
322 lines
10 KiB
C++
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/* Proposed SG14 status_code
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(C) 2018 - 2021 Niall Douglas <http://www.nedproductions.biz/> (5 commits)
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File Created: Aug 2018
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License in the accompanying file
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Licence.txt or at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file Licence.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_OUTCOME_SYSTEM_ERROR2_STD_ERROR_CODE_HPP
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#define BOOST_OUTCOME_SYSTEM_ERROR2_STD_ERROR_CODE_HPP
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#ifndef BOOST_OUTCOME_SYSTEM_ERROR2_NOT_POSIX
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#include "posix_code.hpp"
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#endif
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#if defined(_WIN32) || defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE)
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#include "win32_code.hpp"
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#endif
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#include <system_error>
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BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN
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class _std_error_code_domain;
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//! A `status_code` representing exactly a `std::error_code`
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using std_error_code = status_code<_std_error_code_domain>;
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namespace mixins
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{
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template <class Base> struct mixin<Base, _std_error_code_domain> : public Base
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{
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using Base::Base;
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//! Implicit constructor from a `std::error_code`
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inline mixin(std::error_code ec);
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//! Returns the error code category
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inline const std::error_category &category() const noexcept;
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};
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} // namespace mixins
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/*! The implementation of the domain for `std::error_code` error codes.
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*/
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class _std_error_code_domain final : public status_code_domain
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{
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template <class DomainType> friend class status_code;
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using _base = status_code_domain;
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using _error_code_type = std::error_code;
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using _error_category_type = std::error_category;
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std::string _name;
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static _base::string_ref _make_string_ref(_error_code_type c) noexcept
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{
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#if defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)
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try
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#endif
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{
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std::string msg = c.message();
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auto *p = static_cast<char *>(malloc(msg.size() + 1)); // NOLINT
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if(p == nullptr)
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{
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return _base::string_ref("failed to allocate message");
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}
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memcpy(p, msg.c_str(), msg.size() + 1);
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return _base::atomic_refcounted_string_ref(p, msg.size());
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}
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#if defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)
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catch(...)
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{
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return _base::string_ref("failed to allocate message");
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}
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#endif
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}
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public:
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//! The value type of the `std::error_code` code, which stores the `int` from the `std::error_code`
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using value_type = int;
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using _base::string_ref;
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//! Returns the error category singleton pointer this status code domain represents
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const _error_category_type &error_category() const noexcept
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{
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auto ptr = 0x223a160d20de97b4 ^ this->id();
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return *reinterpret_cast<const _error_category_type *>(ptr);
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}
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//! Default constructor
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explicit _std_error_code_domain(const _error_category_type &category) noexcept
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: _base(0x223a160d20de97b4 ^ reinterpret_cast<_base::unique_id_type>(&category))
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, _name("std_error_code_domain(")
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{
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_name.append(category.name());
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_name.push_back(')');
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}
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_std_error_code_domain(const _std_error_code_domain &) = default;
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_std_error_code_domain(_std_error_code_domain &&) = default;
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_std_error_code_domain &operator=(const _std_error_code_domain &) = default;
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_std_error_code_domain &operator=(_std_error_code_domain &&) = default;
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~_std_error_code_domain() = default;
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static inline const _std_error_code_domain *get(_error_code_type ec);
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virtual string_ref name() const noexcept override { return string_ref(_name.c_str(), _name.size()); } // NOLINT
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virtual payload_info_t payload_info() const noexcept override
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{
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return {sizeof(value_type), sizeof(status_code_domain *) + sizeof(value_type),
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(alignof(value_type) > alignof(status_code_domain *)) ? alignof(value_type) : alignof(status_code_domain *)};
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}
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protected:
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virtual bool _do_failure(const status_code<void> &code) const noexcept override;
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virtual bool _do_equivalent(const status_code<void> &code1, const status_code<void> &code2) const noexcept override;
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virtual generic_code _generic_code(const status_code<void> &code) const noexcept override;
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virtual string_ref _do_message(const status_code<void> &code) const noexcept override;
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#if defined(_CPPUNWIND) || defined(__EXCEPTIONS) || defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE)
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BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN virtual void _do_throw_exception(const status_code<void> &code) const override;
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#endif
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};
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namespace detail
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{
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extern inline _std_error_code_domain *std_error_code_domain_from_category(const std::error_category &category)
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{
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static constexpr size_t max_items = 64;
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static struct storage_t
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{
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std::atomic<unsigned> _lock;
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union item_t
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{
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int _init;
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_std_error_code_domain domain;
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constexpr item_t()
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: _init(0)
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{
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}
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~item_t() {}
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} items[max_items];
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size_t count{0};
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void lock()
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{
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while(_lock.exchange(1, std::memory_order_acquire) != 0)
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;
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}
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void unlock() { _lock.store(0, std::memory_order_release); }
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storage_t() {}
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~storage_t()
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{
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lock();
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for(size_t n = 0; n < count; n++)
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{
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items[n].domain.~_std_error_code_domain();
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}
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unlock();
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}
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_std_error_code_domain *add(const std::error_category &category)
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{
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_std_error_code_domain *ret = nullptr;
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lock();
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for(size_t n = 0; n < count; n++)
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{
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if(items[n].domain.error_category() == category)
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{
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ret = &items[n].domain;
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break;
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}
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}
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if(ret == nullptr && count < max_items)
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{
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ret = new(std::addressof(items[count++].domain)) _std_error_code_domain(category);
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}
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unlock();
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return ret;
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}
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} storage;
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return storage.add(category);
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}
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} // namespace detail
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namespace mixins
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{
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template <class Base>
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inline mixin<Base, _std_error_code_domain>::mixin(std::error_code ec)
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: Base(typename Base::_value_type_constructor{}, _std_error_code_domain::get(ec), ec.value())
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{
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}
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template <class Base> inline const std::error_category &mixin<Base, _std_error_code_domain>::category() const noexcept
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{
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const auto &domain = static_cast<const _std_error_code_domain &>(this->domain());
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return domain.error_category();
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};
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} // namespace mixins
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inline const _std_error_code_domain *_std_error_code_domain::get(std::error_code ec)
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{
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auto *p = detail::std_error_code_domain_from_category(ec.category());
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assert(p != nullptr);
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if(p == nullptr)
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{
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abort();
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}
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return p;
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}
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inline bool _std_error_code_domain::_do_failure(const status_code<void> &code) const noexcept
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{
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assert(code.domain() == *this);
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return static_cast<const std_error_code &>(code).value() != 0; // NOLINT
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}
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inline bool _std_error_code_domain::_do_equivalent(const status_code<void> &code1, const status_code<void> &code2) const noexcept
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{
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assert(code1.domain() == *this);
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const auto &c1 = static_cast<const std_error_code &>(code1); // NOLINT
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const auto &cat1 = c1.category();
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// Are we comparing to another wrapped error_code?
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if(code2.domain() == *this)
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{
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const auto &c2 = static_cast<const std_error_code &>(code2); // NOLINT
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const auto &cat2 = c2.category();
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// If the error code categories are identical, do literal comparison
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if(cat1 == cat2)
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{
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return c1.value() == c2.value();
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}
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// Otherwise fall back onto the _generic_code comparison, which uses default_error_condition()
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return false;
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}
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// Am I an error code with generic category?
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if(cat1 == std::generic_category())
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{
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// Convert to generic code, and compare that
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generic_code _c1(static_cast<errc>(c1.value()));
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return _c1 == code2;
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}
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// Am I an error code with system category?
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if(cat1 == std::system_category())
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{
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// Convert to POSIX or Win32 code, and compare that
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#ifdef _WIN32
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win32_code _c1((win32::DWORD) c1.value());
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return _c1 == code2;
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#elif !defined(BOOST_OUTCOME_SYSTEM_ERROR2_NOT_POSIX)
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posix_code _c1(c1.value());
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return _c1 == code2;
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#endif
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}
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return false;
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}
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inline generic_code _std_error_code_domain::_generic_code(const status_code<void> &code) const noexcept
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{
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assert(code.domain() == *this);
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const auto &c = static_cast<const std_error_code &>(code); // NOLINT
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// Ask my embedded error code for its mapping to std::errc, which is a subset of our generic_code errc.
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std::error_condition cond(c.category().default_error_condition(c.value()));
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if(cond.category() == std::generic_category())
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{
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return generic_code(static_cast<errc>(cond.value()));
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}
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#if !defined(BOOST_OUTCOME_SYSTEM_ERROR2_NOT_POSIX) && !defined(_WIN32)
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if(cond.category() == std::system_category())
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{
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return generic_code(static_cast<errc>(cond.value()));
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}
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#endif
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return errc::unknown;
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}
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inline _std_error_code_domain::string_ref _std_error_code_domain::_do_message(const status_code<void> &code) const noexcept
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{
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assert(code.domain() == *this);
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const auto &c = static_cast<const std_error_code &>(code); // NOLINT
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return _make_string_ref(_error_code_type(c.value(), c.category()));
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}
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#if defined(_CPPUNWIND) || defined(__EXCEPTIONS) || defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE)
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BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN inline void _std_error_code_domain::_do_throw_exception(const status_code<void> &code) const
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{
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assert(code.domain() == *this);
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const auto &c = static_cast<const std_error_code &>(code); // NOLINT
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throw std::system_error(std::error_code(c.value(), c.category()));
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}
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#endif
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static_assert(sizeof(std_error_code) <= sizeof(void *) * 2, "std_error_code does not fit into a system_code!");
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BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END
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// Enable implicit construction of `std_error_code` from `std::error_code`.
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namespace std
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{
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inline BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::std_error_code make_status_code(error_code c) noexcept
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{
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return BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::std_error_code(c);
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}
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} // namespace std
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#endif
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