ceph/src/boost/libs/outcome/test/tests/experimental-p0709a.cpp

   1 /* Unit testing for outcomes
   2 (C) 2017-2019 Niall Douglas <http://www.nedproductions.biz/> (7 commits)
   3
   4
   5 Boost Software License - Version 1.0 - August 17th, 2003
   6
   7 Permission is hereby granted, free of charge, to any person or organization
   8 obtaining a copy of the software and accompanying documentation covered by
   9 this license (the "Software") to use, reproduce, display, distribute,
  10 execute, and transmit the Software, and to prepare derivative works of the
  11 Software, and to permit third-parties to whom the Software is furnished to
  12 do so, all subject to the following:
  13
  14 The copyright notices in the Software and this entire statement, including
  15 the above license grant, this restriction and the following disclaimer,
  16 must be included in all copies of the Software, in whole or in part, and
  17 all derivative works of the Software, unless such copies or derivative
  18 works are solely in the form of machine-executable object code generated by
  19 a source language processor.
  20
  21 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
  24 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
  25 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
  26 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  27 DEALINGS IN THE SOFTWARE.
  28 */
  29
  30 #include <boost/outcome/experimental/status_result.hpp>
  31
  32 #include <climits>  // for INT_MAX
  33 #include <cstdio>
  34
  35 // status_code<erased<intptr_t>>
  36 using error = BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::error;
  37 // Outcome's result must be told when it is dealing with an erased status code
  38 template <class T, class E> using result = BOOST_OUTCOME_V2_NAMESPACE::experimental::status_result<T, E, BOOST_OUTCOME_V2_NAMESPACE::policy::all_narrow>;
  39
  40 enum class arithmetic_errc
  41 {
  42   success,
  43   divide_by_zero,
  44   integer_divide_overflows,
  45   not_integer_division
  46 };
  47
  48 class _arithmetic_errc_domain;
  49 using arithmetic_errc_error = BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<_arithmetic_errc_domain>;
  50
  51 class _arithmetic_errc_domain : public BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code_domain
  52 {
  53   using _base = BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code_domain;
  54
  55 public:
  56   using value_type = arithmetic_errc;
  57
  58   constexpr explicit _arithmetic_errc_domain(typename _base::unique_id_type id = 0x290f170194f0c6c7) noexcept : _base(id) {}
  59   static inline constexpr const _arithmetic_errc_domain &get();
  60
  61   virtual _base::string_ref name() const noexcept override final  // NOLINT
  62   {
  63     static string_ref v("arithmetic error domain");
  64     return v;  // NOLINT
  65   }
  66
  67 protected:
  68   virtual bool _do_failure(const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &code) const noexcept override final  // NOLINT
  69   {
  70     assert(code.domain() == *this);                                     // NOLINT
  71     const auto &c1 = static_cast<const arithmetic_errc_error &>(code);  // NOLINT
  72     return c1.value() != arithmetic_errc::success;
  73   }
  74   virtual bool _do_equivalent(const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &, const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &) const noexcept override final { return false; }  // NOLINT
  75   virtual BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::generic_code _generic_code(const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &) const noexcept override final { return {}; }                         // NOLINT
  76   virtual _base::string_ref _do_message(const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &code) const noexcept override final                                                          // NOLINT
  77   {
  78     assert(code.domain() == *this);                                     // NOLINT
  79     const auto &c1 = static_cast<const arithmetic_errc_error &>(code);  // NOLINT
  80     switch(c1.value())
  81     {
  82     case arithmetic_errc::success:
  83       return _base::string_ref("success");
  84     case arithmetic_errc::divide_by_zero:
  85       return _base::string_ref("divide by zero");
  86     case arithmetic_errc::integer_divide_overflows:
  87       return _base::string_ref("integer divide overflows");
  88     case arithmetic_errc::not_integer_division:
  89       return _base::string_ref("not integer division");
  90     }
  91     return _base::string_ref("unknown");
  92   }
  93   BOOST_OUTCOME_SYSTEM_ERROR2_NORETURN virtual void _do_throw_exception(const BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::status_code<void> &) const override final { abort(); }  // NOLINT
  94 };
  95
  96 constexpr _arithmetic_errc_domain arithmetic_errc_domain;
  97 inline constexpr const _arithmetic_errc_domain &_arithmetic_errc_domain::get()
  98 {
  99   return arithmetic_errc_domain;
 100 }
 101
 102
 103 // Tell status code about the available implicit conversion
 104 inline arithmetic_errc_error make_status_code(arithmetic_errc e)
 105 {
 106   return arithmetic_errc_error(BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::in_place, e);
 107 }
 108
 109 BOOST_OUTCOME_V2_NAMESPACE_BEGIN
 110 namespace trait
 111 {
 112   // Tell Outcome that arithmetic_errc is convertible into std::error
 113   template <> struct is_error_type_enum<error, arithmetic_errc>
 114   {
 115     static constexpr bool value = true;
 116   };
 117 }
 118 BOOST_OUTCOME_V2_NAMESPACE_END
 119 // And tell Outcome how to perform the implicit conversion
 120 inline error make_error_code(arithmetic_errc e)
 121 {
 122   return arithmetic_errc_error(BOOST_OUTCOME_SYSTEM_ERROR2_NAMESPACE::in_place, e);
 123 }
 124
 125
 126 result<int, error> safe_divide(int i, int j)
 127 {
 128   if(j == 0)
 129   {
 130     return arithmetic_errc::divide_by_zero;
 131   }
 132   if(i == INT_MIN && j == -1)
 133   {
 134     return arithmetic_errc::integer_divide_overflows;
 135   }
 136   if(i % j != 0)
 137   {
 138     return arithmetic_errc::not_integer_division;
 139   }
 140   return i / j;
 141 }
 142
 143 int caller2(int i, int j)
 144 {
 145   auto r = safe_divide(i, j);
 146   if(r)
 147   {
 148     return r.value();
 149   }
 150   if(r.error() == arithmetic_errc::divide_by_zero)
 151   {
 152     return 0;
 153   }
 154   if(r.error() == arithmetic_errc::not_integer_division)
 155   {
 156     return i / j;  // ignore
 157   }
 158   if(r.error() == arithmetic_errc::integer_divide_overflows)
 159   {
 160     return INT_MIN;
 161   }
 162   return 0;
 163 }
 164
 165 int main()
 166 {
 167   printf("%d\n", caller2(5, 6));  // NOLINT
 168   return 0;
 169 }