ceph/src/boost/boost/outcome/experimental/status-code/status_code_ptr.hpp

   1 /* Pointer to a SG14 status_code
   2 (C) 2018-2020 Niall Douglas <http://www.nedproductions.biz/> (5 commits)
   3 File Created: Sep 2018
   4
   5
   6 Boost Software License - Version 1.0 - August 17th, 2003
   7
   8 Permission is hereby granted, free of charge, to any person or organization
   9 obtaining a copy of the software and accompanying documentation covered by
  10 this license (the "Software") to use, reproduce, display, distribute,
  11 execute, and transmit the Software, and to prepare derivative works of the
  12 Software, and to permit third-parties to whom the Software is furnished to
  13 do so, all subject to the following:
  14
  15 The copyright notices in the Software and this entire statement, including
  16 the above license grant, this restriction and the following disclaimer,
  17 must be included in all copies of the Software, in whole or in part, and
  18 all derivative works of the Software, unless such copies or derivative
  19 works are solely in the form of machine-executable object code generated by
  20 a source language processor.
  21
  22 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  23 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
  25 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
  26 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
  27 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  28 DEALINGS IN THE SOFTWARE.
  29 */
  30
  31 #ifndef BOOST_OUTCOME_SYSTEM_ERROR2_STATUS_CODE_PTR_HPP
  32 #define BOOST_OUTCOME_SYSTEM_ERROR2_STATUS_CODE_PTR_HPP
  33
  34 #include "status_code.hpp"
  35
  36 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_BEGIN
  37
  38 namespace detail
  39 {
  40   template <class StatusCode> class indirecting_domain : public status_code_domain
  41   {
  42     template <class DomainType> friend class status_code;
  43     using _base = status_code_domain;
  44
  45   public:
  46     using value_type = StatusCode *;
  47     using _base::string_ref;
  48
  49     constexpr indirecting_domain() noexcept
  50         : _base(0xc44f7bdeb2cc50e9 ^ typename StatusCode::domain_type().id() /* unique-ish based on domain's unique id */)
  51     {
  52     }
  53     indirecting_domain(const indirecting_domain &) = default;
  54     indirecting_domain(indirecting_domain &&) = default;  // NOLINT
  55     indirecting_domain &operator=(const indirecting_domain &) = default;
  56     indirecting_domain &operator=(indirecting_domain &&) = default;  // NOLINT
  57     ~indirecting_domain() = default;
  58
  59 #if __cplusplus < 201402L && !defined(_MSC_VER)
  60     static inline const indirecting_domain &get()
  61     {
  62       static indirecting_domain v;
  63       return v;
  64     }
  65 #else
  66     static inline constexpr const indirecting_domain &get();
  67 #endif
  68
  69     virtual string_ref name() const noexcept override { return typename StatusCode::domain_type().name(); }  // NOLINT
  70   protected:
  71     using _mycode = status_code<indirecting_domain>;
  72     virtual bool _do_failure(const status_code<void> &code) const noexcept override  // NOLINT
  73     {
  74       assert(code.domain() == *this);
  75       const auto &c = static_cast<const _mycode &>(code);  // NOLINT
  76       return typename StatusCode::domain_type()._do_failure(*c.value());
  77     }
  78     virtual bool _do_equivalent(const status_code<void> &code1, const status_code<void> &code2) const noexcept override  // NOLINT
  79     {
  80       assert(code1.domain() == *this);
  81       const auto &c1 = static_cast<const _mycode &>(code1);  // NOLINT
  82       return typename StatusCode::domain_type()._do_equivalent(*c1.value(), code2);
  83     }
  84     virtual generic_code _generic_code(const status_code<void> &code) const noexcept override  // NOLINT
  85     {
  86       assert(code.domain() == *this);
  87       const auto &c = static_cast<const _mycode &>(code);  // NOLINT
  88       return typename StatusCode::domain_type()._generic_code(*c.value());
  89     }
  90     virtual string_ref _do_message(const status_code<void> &code) const noexcept override  // NOLINT
  91     {
  92       assert(code.domain() == *this);
  93       const auto &c = static_cast<const _mycode &>(code);  // NOLINT
  94       return typename StatusCode::domain_type()._do_message(*c.value());
  95     }
  96 #if defined(_CPPUNWIND) || defined(__EXCEPTIONS) || defined(BOOST_OUTCOME_STANDARDESE_IS_IN_THE_HOUSE)
  97     BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN virtual void _do_throw_exception(const status_code<void> &code) const override  // NOLINT
  98     {
  99       assert(code.domain() == *this);
 100       const auto &c = static_cast<const _mycode &>(code);  // NOLINT
 101       typename StatusCode::domain_type()._do_throw_exception(*c.value());
 102     }
 103 #endif
 104     virtual void _do_erased_copy(status_code<void> &dst, const status_code<void> &src, size_t /*unused*/) const override  // NOLINT
 105     {
 106       // Note that dst will not have its domain set
 107       assert(src.domain() == *this);
 108       auto &d = static_cast<_mycode &>(dst);               // NOLINT
 109       const auto &_s = static_cast<const _mycode &>(src);  // NOLINT
 110       const StatusCode &s = *_s.value();
 111       new(&d) _mycode(in_place, new StatusCode(s));
 112     }
 113     virtual void _do_erased_destroy(status_code<void> &code, size_t /*unused*/) const noexcept override  // NOLINT
 114     {
 115       assert(code.domain() == *this);
 116       auto &c = static_cast<_mycode &>(code);  // NOLINT
 117       delete c.value();                        // NOLINT
 118     }
 119   };
 120 #if __cplusplus >= 201402L || defined(_MSC_VER)
 121   template <class StatusCode> constexpr indirecting_domain<StatusCode> _indirecting_domain{};
 122   template <class StatusCode> inline constexpr const indirecting_domain<StatusCode> &indirecting_domain<StatusCode>::get() { return _indirecting_domain<StatusCode>; }
 123 #endif
 124 }  // namespace detail
 125
 126 /*! Make an erased status code which indirects to a dynamically allocated status code.
 127 This is useful for shoehorning a rich status code with large value type into a small
 128 erased status code like `system_code`, with which the status code generated by this
 129 function is compatible. Note that this function can throw due to `bad_alloc`.
 130 */
 131 template <class T, typename std::enable_if<is_status_code<T>::value, bool>::type = true>  //
 132 inline status_code<erased<typename std::add_pointer<typename std::decay<T>::type>::type>> make_status_code_ptr(T &&v)
 133 {
 134   using status_code_type = typename std::decay<T>::type;
 135   return status_code<detail::indirecting_domain<status_code_type>>(in_place, new status_code_type(static_cast<T &&>(v)));
 136 }
 137
 138 /*! If a status code refers to a `status_code_ptr` which indirects to a status
 139 code of type `StatusCode`, return a pointer to that `StatusCode`. Otherwise return null.
 140 */
 141 template <class StatusCode, class U, typename std::enable_if<is_status_code<StatusCode>::value, bool>::type = true> inline StatusCode *get_if(status_code<erased<U>> *v) noexcept
 142 {
 143   if((0xc44f7bdeb2cc50e9 ^ typename StatusCode::domain_type().id()) != v->domain().id())
 144   {
 145     return nullptr;
 146   }
 147   union {
 148     U value;
 149     StatusCode *ret;
 150   };
 151   value = v->value();
 152   return ret;
 153 }
 154 //! \overload Const overload
 155 template <class StatusCode, class U, typename std::enable_if<is_status_code<StatusCode>::value, bool>::type = true> inline const StatusCode *get_if(const status_code<erased<U>> *v) noexcept
 156 {
 157   if((0xc44f7bdeb2cc50e9 ^ typename StatusCode::domain_type().id()) != v->domain().id())
 158   {
 159     return nullptr;
 160   }
 161   union {
 162     U value;
 163     const StatusCode *ret;
 164   };
 165   value = v->value();
 166   return ret;
 167 }
 168
 169 /*! If a status code refers to a `status_code_ptr`, return the id of the erased
 170 status code's domain. Otherwise return a meaningless number.
 171 */
 172 template <class U> inline typename status_code_domain::unique_id_type get_id(const status_code<erased<U>> &v) noexcept
 173 {
 174   return 0xc44f7bdeb2cc50e9 ^ v.domain().id();
 175 }
 176
 177 BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE_END
 178
 179 #endif