libcxx/include/__compare/ordering.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___COMPARE_ORDERING_H
  10 #define _LIBCPP___COMPARE_ORDERING_H
  11
  12 #include <__config>
  13 #include <__type_traits/enable_if.h>
  14 #include <__type_traits/is_same.h>
  15
  16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  17 #  pragma GCC system_header
  18 #endif
  19
  20 _LIBCPP_BEGIN_NAMESPACE_STD
  21
  22 #if _LIBCPP_STD_VER >= 20
  23
  24 // exposition only
  25 enum class _OrdResult : signed char { __less = -1, __equiv = 0, __greater = 1 };
  26
  27 enum class _PartialOrdResult : signed char {
  28   __less      = static_cast<signed char>(_OrdResult::__less),
  29   __equiv     = static_cast<signed char>(_OrdResult::__equiv),
  30   __greater   = static_cast<signed char>(_OrdResult::__greater),
  31   __unordered = -127,
  32 };
  33
  34 class partial_ordering;
  35 class weak_ordering;
  36 class strong_ordering;
  37
  38 struct _CmpUnspecifiedParam {
  39   // If anything other than a literal 0 is provided, the behavior is undefined by the Standard.
  40   //
  41   // The alternative to the `__enable_if__` attribute would be to use the fact that a pointer
  42   // can be constructed from literal 0, but this conflicts with `-Wzero-as-null-pointer-constant`.
  43   template <class _Tp, class = __enable_if_t<is_same_v<_Tp, int> > >
  44   _LIBCPP_HIDE_FROM_ABI consteval _CmpUnspecifiedParam(_Tp __zero) noexcept
  45 #  if __has_attribute(__enable_if__)
  46       __attribute__((__enable_if__(
  47           __zero == 0, "Only literal 0 is allowed as the operand of a comparison with one of the ordering types")))
  48 #  endif
  49   {
  50     (void)__zero;
  51   }
  52 };
  53
  54 class partial_ordering {
  55   _LIBCPP_HIDE_FROM_ABI explicit constexpr partial_ordering(_PartialOrdResult __v) noexcept : __value_(__v) {}
  56
  57 public:
  58   // valid values
  59   static const partial_ordering less;
  60   static const partial_ordering equivalent;
  61   static const partial_ordering greater;
  62   static const partial_ordering unordered;
  63
  64   // comparisons
  65   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(partial_ordering, partial_ordering) noexcept = default;
  66
  67   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
  68     return __v.__value_ == _PartialOrdResult::__equiv;
  69   }
  70
  71   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
  72     return __v.__value_ == _PartialOrdResult::__less;
  73   }
  74
  75   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
  76     return __v.__value_ == _PartialOrdResult::__equiv || __v.__value_ == _PartialOrdResult::__less;
  77   }
  78
  79   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
  80     return __v.__value_ == _PartialOrdResult::__greater;
  81   }
  82
  83   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
  84     return __v.__value_ == _PartialOrdResult::__equiv || __v.__value_ == _PartialOrdResult::__greater;
  85   }
  86
  87   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(_CmpUnspecifiedParam, partial_ordering __v) noexcept {
  88     return __v.__value_ == _PartialOrdResult::__greater;
  89   }
  90
  91   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(_CmpUnspecifiedParam, partial_ordering __v) noexcept {
  92     return __v.__value_ == _PartialOrdResult::__equiv || __v.__value_ == _PartialOrdResult::__greater;
  93   }
  94
  95   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(_CmpUnspecifiedParam, partial_ordering __v) noexcept {
  96     return __v.__value_ == _PartialOrdResult::__less;
  97   }
  98
  99   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(_CmpUnspecifiedParam, partial_ordering __v) noexcept {
 100     return __v.__value_ == _PartialOrdResult::__equiv || __v.__value_ == _PartialOrdResult::__less;
 101   }
 102
 103   _LIBCPP_HIDE_FROM_ABI friend constexpr partial_ordering
 104   operator<=>(partial_ordering __v, _CmpUnspecifiedParam) noexcept {
 105     return __v;
 106   }
 107
 108   _LIBCPP_HIDE_FROM_ABI friend constexpr partial_ordering
 109   operator<=>(_CmpUnspecifiedParam, partial_ordering __v) noexcept {
 110     return __v < 0 ? partial_ordering::greater : (__v > 0 ? partial_ordering::less : __v);
 111   }
 112
 113 private:
 114   _PartialOrdResult __value_;
 115 };
 116
 117 inline constexpr partial_ordering partial_ordering::less(_PartialOrdResult::__less);
 118 inline constexpr partial_ordering partial_ordering::equivalent(_PartialOrdResult::__equiv);
 119 inline constexpr partial_ordering partial_ordering::greater(_PartialOrdResult::__greater);
 120 inline constexpr partial_ordering partial_ordering::unordered(_PartialOrdResult::__unordered);
 121
 122 class weak_ordering {
 123   using _ValueT = signed char;
 124
 125   _LIBCPP_HIDE_FROM_ABI explicit constexpr weak_ordering(_OrdResult __v) noexcept : __value_(_ValueT(__v)) {}
 126
 127 public:
 128   static const weak_ordering less;
 129   static const weak_ordering equivalent;
 130   static const weak_ordering greater;
 131
 132   _LIBCPP_HIDE_FROM_ABI constexpr operator partial_ordering() const noexcept {
 133     return __value_ == 0 ? partial_ordering::equivalent
 134                          : (__value_ < 0 ? partial_ordering::less : partial_ordering::greater);
 135   }
 136
 137   // comparisons
 138   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(weak_ordering, weak_ordering) noexcept = default;
 139
 140   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
 141     return __v.__value_ == 0;
 142   }
 143
 144   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
 145     return __v.__value_ < 0;
 146   }
 147
 148   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
 149     return __v.__value_ <= 0;
 150   }
 151
 152   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
 153     return __v.__value_ > 0;
 154   }
 155
 156   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
 157     return __v.__value_ >= 0;
 158   }
 159
 160   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
 161     return 0 < __v.__value_;
 162   }
 163
 164   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
 165     return 0 <= __v.__value_;
 166   }
 167
 168   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
 169     return 0 > __v.__value_;
 170   }
 171
 172   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
 173     return 0 >= __v.__value_;
 174   }
 175
 176   _LIBCPP_HIDE_FROM_ABI friend constexpr weak_ordering operator<=>(weak_ordering __v, _CmpUnspecifiedParam) noexcept {
 177     return __v;
 178   }
 179
 180   _LIBCPP_HIDE_FROM_ABI friend constexpr weak_ordering operator<=>(_CmpUnspecifiedParam, weak_ordering __v) noexcept {
 181     return __v < 0 ? weak_ordering::greater : (__v > 0 ? weak_ordering::less : __v);
 182   }
 183
 184 private:
 185   _ValueT __value_;
 186 };
 187
 188 inline constexpr weak_ordering weak_ordering::less(_OrdResult::__less);
 189 inline constexpr weak_ordering weak_ordering::equivalent(_OrdResult::__equiv);
 190 inline constexpr weak_ordering weak_ordering::greater(_OrdResult::__greater);
 191
 192 class strong_ordering {
 193   using _ValueT = signed char;
 194
 195   _LIBCPP_HIDE_FROM_ABI explicit constexpr strong_ordering(_OrdResult __v) noexcept : __value_(_ValueT(__v)) {}
 196
 197 public:
 198   static const strong_ordering less;
 199   static const strong_ordering equal;
 200   static const strong_ordering equivalent;
 201   static const strong_ordering greater;
 202
 203   // conversions
 204   _LIBCPP_HIDE_FROM_ABI constexpr operator partial_ordering() const noexcept {
 205     return __value_ == 0 ? partial_ordering::equivalent
 206                          : (__value_ < 0 ? partial_ordering::less : partial_ordering::greater);
 207   }
 208
 209   _LIBCPP_HIDE_FROM_ABI constexpr operator weak_ordering() const noexcept {
 210     return __value_ == 0 ? weak_ordering::equivalent : (__value_ < 0 ? weak_ordering::less : weak_ordering::greater);
 211   }
 212
 213   // comparisons
 214   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(strong_ordering, strong_ordering) noexcept = default;
 215
 216   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
 217     return __v.__value_ == 0;
 218   }
 219
 220   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
 221     return __v.__value_ < 0;
 222   }
 223
 224   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
 225     return __v.__value_ <= 0;
 226   }
 227
 228   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
 229     return __v.__value_ > 0;
 230   }
 231
 232   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
 233     return __v.__value_ >= 0;
 234   }
 235
 236   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
 237     return 0 < __v.__value_;
 238   }
 239
 240   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator<=(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
 241     return 0 <= __v.__value_;
 242   }
 243
 244   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
 245     return 0 > __v.__value_;
 246   }
 247
 248   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator>=(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
 249     return 0 >= __v.__value_;
 250   }
 251
 252   _LIBCPP_HIDE_FROM_ABI friend constexpr strong_ordering
 253   operator<=>(strong_ordering __v, _CmpUnspecifiedParam) noexcept {
 254     return __v;
 255   }
 256
 257   _LIBCPP_HIDE_FROM_ABI friend constexpr strong_ordering
 258   operator<=>(_CmpUnspecifiedParam, strong_ordering __v) noexcept {
 259     return __v < 0 ? strong_ordering::greater : (__v > 0 ? strong_ordering::less : __v);
 260   }
 261
 262 private:
 263   _ValueT __value_;
 264 };
 265
 266 inline constexpr strong_ordering strong_ordering::less(_OrdResult::__less);
 267 inline constexpr strong_ordering strong_ordering::equal(_OrdResult::__equiv);
 268 inline constexpr strong_ordering strong_ordering::equivalent(_OrdResult::__equiv);
 269 inline constexpr strong_ordering strong_ordering::greater(_OrdResult::__greater);
 270
 271 /// [cmp.categories.pre]/1
 272 /// The types partial_ordering, weak_ordering, and strong_ordering are
 273 /// collectively termed the comparison category types.
 274 template <class _Tp>
 275 concept __comparison_category =
 276     is_same_v<_Tp, partial_ordering> || is_same_v<_Tp, weak_ordering> || is_same_v<_Tp, strong_ordering>;
 277
 278 #endif // _LIBCPP_STD_VER >= 20
 279
 280 _LIBCPP_END_NAMESPACE_STD
 281
 282 #endif // _LIBCPP___COMPARE_ORDERING_H