libcxx/include/__system_error/error_condition.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___SYSTEM_ERROR_ERROR_CONDITION_H
  11 #define _LIBCPP___SYSTEM_ERROR_ERROR_CONDITION_H
  12
  13 #include <__compare/ordering.h>
  14 #include <__config>
  15 #include <__functional/hash.h>
  16 #include <__functional/unary_function.h>
  17 #include <__system_error/errc.h>
  18 #include <__system_error/error_category.h>
  19 #include <cstddef>
  20 #include <string>
  21
  22 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  23 #  pragma GCC system_header
  24 #endif
  25
  26 _LIBCPP_BEGIN_NAMESPACE_STD
  27
  28 template <class _Tp>
  29 struct _LIBCPP_TEMPLATE_VIS is_error_condition_enum : public false_type {};
  30
  31 #if _LIBCPP_STD_VER >= 17
  32 template <class _Tp>
  33 inline constexpr bool is_error_condition_enum_v = is_error_condition_enum<_Tp>::value;
  34 #endif
  35
  36 template <>
  37 struct _LIBCPP_TEMPLATE_VIS is_error_condition_enum<errc> : true_type {};
  38
  39 #ifdef _LIBCPP_CXX03_LANG
  40 template <>
  41 struct _LIBCPP_TEMPLATE_VIS is_error_condition_enum<errc::__lx> : true_type {};
  42 #endif
  43
  44 namespace __adl_only {
  45 // Those cause ADL to trigger but they are not viable candidates,
  46 // so they are never actually selected.
  47 void make_error_condition() = delete;
  48 } // namespace __adl_only
  49
  50 class _LIBCPP_EXPORTED_FROM_ABI error_condition {
  51   int __val_;
  52   const error_category* __cat_;
  53
  54 public:
  55   _LIBCPP_HIDE_FROM_ABI error_condition() _NOEXCEPT : __val_(0), __cat_(&generic_category()) {}
  56
  57   _LIBCPP_HIDE_FROM_ABI error_condition(int __val, const error_category& __cat) _NOEXCEPT
  58       : __val_(__val),
  59         __cat_(&__cat) {}
  60
  61   template <class _Ep, __enable_if_t<is_error_condition_enum<_Ep>::value, int> = 0>
  62   _LIBCPP_HIDE_FROM_ABI error_condition(_Ep __e) _NOEXCEPT {
  63     using __adl_only::make_error_condition;
  64     *this = make_error_condition(__e);
  65   }
  66
  67   _LIBCPP_HIDE_FROM_ABI void assign(int __val, const error_category& __cat) _NOEXCEPT {
  68     __val_ = __val;
  69     __cat_ = &__cat;
  70   }
  71
  72   template <class _Ep, __enable_if_t<is_error_condition_enum<_Ep>::value, int> = 0>
  73   _LIBCPP_HIDE_FROM_ABI error_condition& operator=(_Ep __e) _NOEXCEPT {
  74     using __adl_only::make_error_condition;
  75     *this = make_error_condition(__e);
  76     return *this;
  77   }
  78
  79   _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT {
  80     __val_ = 0;
  81     __cat_ = &generic_category();
  82   }
  83
  84   _LIBCPP_HIDE_FROM_ABI int value() const _NOEXCEPT { return __val_; }
  85
  86   _LIBCPP_HIDE_FROM_ABI const error_category& category() const _NOEXCEPT { return *__cat_; }
  87   string message() const;
  88
  89   _LIBCPP_HIDE_FROM_ABI explicit operator bool() const _NOEXCEPT { return __val_ != 0; }
  90 };
  91
  92 inline _LIBCPP_HIDE_FROM_ABI error_condition make_error_condition(errc __e) _NOEXCEPT {
  93   return error_condition(static_cast<int>(__e), generic_category());
  94 }
  95
  96 inline _LIBCPP_HIDE_FROM_ABI bool operator==(const error_condition& __x, const error_condition& __y) _NOEXCEPT {
  97   return __x.category() == __y.category() && __x.value() == __y.value();
  98 }
  99
 100 #if _LIBCPP_STD_VER <= 17
 101
 102 inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const error_condition& __x, const error_condition& __y) _NOEXCEPT {
 103   return !(__x == __y);
 104 }
 105
 106 inline _LIBCPP_HIDE_FROM_ABI bool operator<(const error_condition& __x, const error_condition& __y) _NOEXCEPT {
 107   return __x.category() < __y.category() || (__x.category() == __y.category() && __x.value() < __y.value());
 108 }
 109
 110 #else // _LIBCPP_STD_VER <= 17
 111
 112 inline _LIBCPP_HIDE_FROM_ABI strong_ordering
 113 operator<=>(const error_condition& __x, const error_condition& __y) noexcept {
 114   if (auto __c = __x.category() <=> __y.category(); __c != 0)
 115     return __c;
 116   return __x.value() <=> __y.value();
 117 }
 118
 119 #endif // _LIBCPP_STD_VER <= 17
 120
 121 template <>
 122 struct _LIBCPP_TEMPLATE_VIS hash<error_condition> : public __unary_function<error_condition, size_t> {
 123   _LIBCPP_HIDE_FROM_ABI size_t operator()(const error_condition& __ec) const _NOEXCEPT {
 124     return static_cast<size_t>(__ec.value());
 125   }
 126 };
 127
 128 _LIBCPP_END_NAMESPACE_STD
 129
 130 #endif // _LIBCPP___SYSTEM_ERROR_ERROR_CONDITION_H