1 // Definition of numeric_limits replacement traits P1841R1 -*- C++ -*- 2 3 // Copyright (C) 2020-2021 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 11 // This library is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 #include <type_traits> 26 27 namespace std { 28 29 template <template <typename> class _Trait, typename _Tp, typename = void> 30 struct __value_exists_impl : false_type {}; 31 32 template <template <typename> class _Trait, typename _Tp> 33 struct __value_exists_impl<_Trait, _Tp, void_t<decltype(_Trait<_Tp>::value)>> 34 : true_type {}; 35 36 template <typename _Tp, bool = is_arithmetic_v<_Tp>> 37 struct __digits_impl {}; 38 39 template <typename _Tp> 40 struct __digits_impl<_Tp, true> 41 { 42 static inline constexpr int value 43 = sizeof(_Tp) * __CHAR_BIT__ - is_signed_v<_Tp>; 44 }; 45 46 template <> 47 struct __digits_impl<float, true> 48 { static inline constexpr int value = __FLT_MANT_DIG__; }; 49 50 template <> 51 struct __digits_impl<double, true> 52 { static inline constexpr int value = __DBL_MANT_DIG__; }; 53 54 template <> 55 struct __digits_impl<long double, true> 56 { static inline constexpr int value = __LDBL_MANT_DIG__; }; 57 58 template <typename _Tp, bool = is_arithmetic_v<_Tp>> 59 struct __digits10_impl {}; 60 61 template <typename _Tp> 62 struct __digits10_impl<_Tp, true> 63 { 64 // The fraction 643/2136 approximates log10(2) to 7 significant digits. 65 static inline constexpr int value = __digits_impl<_Tp>::value * 643L / 2136; 66 }; 67 68 template <> 69 struct __digits10_impl<float, true> 70 { static inline constexpr int value = __FLT_DIG__; }; 71 72 template <> 73 struct __digits10_impl<double, true> 74 { static inline constexpr int value = __DBL_DIG__; }; 75 76 template <> 77 struct __digits10_impl<long double, true> 78 { static inline constexpr int value = __LDBL_DIG__; }; 79 80 template <typename _Tp, bool = is_arithmetic_v<_Tp>> 81 struct __max_digits10_impl {}; 82 83 template <typename _Tp> 84 struct __max_digits10_impl<_Tp, true> 85 { 86 static inline constexpr int value 87 = is_floating_point_v<_Tp> ? 2 + __digits_impl<_Tp>::value * 643L / 2136 88 : __digits10_impl<_Tp>::value + 1; 89 }; 90 91 template <typename _Tp> 92 struct __max_exponent_impl {}; 93 94 template <> 95 struct __max_exponent_impl<float> 96 { static inline constexpr int value = __FLT_MAX_EXP__; }; 97 98 template <> 99 struct __max_exponent_impl<double> 100 { static inline constexpr int value = __DBL_MAX_EXP__; }; 101 102 template <> 103 struct __max_exponent_impl<long double> 104 { static inline constexpr int value = __LDBL_MAX_EXP__; }; 105 106 template <typename _Tp> 107 struct __max_exponent10_impl {}; 108 109 template <> 110 struct __max_exponent10_impl<float> 111 { static inline constexpr int value = __FLT_MAX_10_EXP__; }; 112 113 template <> 114 struct __max_exponent10_impl<double> 115 { static inline constexpr int value = __DBL_MAX_10_EXP__; }; 116 117 template <> 118 struct __max_exponent10_impl<long double> 119 { static inline constexpr int value = __LDBL_MAX_10_EXP__; }; 120 121 template <typename _Tp> 122 struct __min_exponent_impl {}; 123 124 template <> 125 struct __min_exponent_impl<float> 126 { static inline constexpr int value = __FLT_MIN_EXP__; }; 127 128 template <> 129 struct __min_exponent_impl<double> 130 { static inline constexpr int value = __DBL_MIN_EXP__; }; 131 132 template <> 133 struct __min_exponent_impl<long double> 134 { static inline constexpr int value = __LDBL_MIN_EXP__; }; 135 136 template <typename _Tp> 137 struct __min_exponent10_impl {}; 138 139 template <> 140 struct __min_exponent10_impl<float> 141 { static inline constexpr int value = __FLT_MIN_10_EXP__; }; 142 143 template <> 144 struct __min_exponent10_impl<double> 145 { static inline constexpr int value = __DBL_MIN_10_EXP__; }; 146 147 template <> 148 struct __min_exponent10_impl<long double> 149 { static inline constexpr int value = __LDBL_MIN_10_EXP__; }; 150 151 template <typename _Tp, bool = is_arithmetic_v<_Tp>> 152 struct __radix_impl {}; 153 154 template <typename _Tp> 155 struct __radix_impl<_Tp, true> 156 { 157 static inline constexpr int value 158 = is_floating_point_v<_Tp> ? __FLT_RADIX__ : 2; 159 }; 160 161 // [num.traits.util], numeric utility traits 162 template <template <typename> class _Trait, typename _Tp> 163 struct __value_exists : __value_exists_impl<_Trait, _Tp> {}; 164 165 template <template <typename> class _Trait, typename _Tp> 166 inline constexpr bool __value_exists_v = __value_exists<_Trait, _Tp>::value; 167 168 template <template <typename> class _Trait, typename _Tp, typename _Up = _Tp> 169 inline constexpr _Up 170 __value_or(_Up __def = _Up()) noexcept 171 { 172 if constexpr (__value_exists_v<_Trait, _Tp>) 173 return static_cast<_Up>(_Trait<_Tp>::value); 174 else 175 return __def; 176 } 177 178 template <typename _Tp, bool = is_arithmetic_v<_Tp>> 179 struct __norm_min_impl {}; 180 181 template <typename _Tp> 182 struct __norm_min_impl<_Tp, true> 183 { static inline constexpr _Tp value = 1; }; 184 185 template <> 186 struct __norm_min_impl<float, true> 187 { static inline constexpr float value = __FLT_MIN__; }; 188 189 template <> 190 struct __norm_min_impl<double, true> 191 { static inline constexpr double value = __DBL_MIN__; }; 192 193 template <> 194 struct __norm_min_impl<long double, true> 195 { static inline constexpr long double value = __LDBL_MIN__; }; 196 197 template <typename _Tp> 198 struct __denorm_min_impl : __norm_min_impl<_Tp> {}; 199 200 #if __FLT_HAS_DENORM__ 201 template <> 202 struct __denorm_min_impl<float> 203 { static inline constexpr float value = __FLT_DENORM_MIN__; }; 204 #endif 205 206 #if __DBL_HAS_DENORM__ 207 template <> 208 struct __denorm_min_impl<double> 209 { static inline constexpr double value = __DBL_DENORM_MIN__; }; 210 #endif 211 212 #if __LDBL_HAS_DENORM__ 213 template <> 214 struct __denorm_min_impl<long double> 215 { static inline constexpr long double value = __LDBL_DENORM_MIN__; }; 216 #endif 217 218 template <typename _Tp> 219 struct __epsilon_impl {}; 220 221 template <> 222 struct __epsilon_impl<float> 223 { static inline constexpr float value = __FLT_EPSILON__; }; 224 225 template <> 226 struct __epsilon_impl<double> 227 { static inline constexpr double value = __DBL_EPSILON__; }; 228 229 template <> 230 struct __epsilon_impl<long double> 231 { static inline constexpr long double value = __LDBL_EPSILON__; }; 232 233 template <typename _Tp, bool = is_arithmetic_v<_Tp>> 234 struct __finite_min_impl {}; 235 236 template <typename _Tp> 237 struct __finite_min_impl<_Tp, true> 238 { 239 static inline constexpr _Tp value 240 = is_unsigned_v<_Tp> ? _Tp() 241 : -2 * (_Tp(1) << __digits_impl<_Tp>::value - 1); 242 }; 243 244 template <> 245 struct __finite_min_impl<float, true> 246 { static inline constexpr float value = -__FLT_MAX__; }; 247 248 template <> 249 struct __finite_min_impl<double, true> 250 { static inline constexpr double value = -__DBL_MAX__; }; 251 252 template <> 253 struct __finite_min_impl<long double, true> 254 { static inline constexpr long double value = -__LDBL_MAX__; }; 255 256 template <typename _Tp, bool = is_arithmetic_v<_Tp>> 257 struct __finite_max_impl {}; 258 259 template <typename _Tp> 260 struct __finite_max_impl<_Tp, true> 261 { static inline constexpr _Tp value = ~__finite_min_impl<_Tp>::value; }; 262 263 template <> 264 struct __finite_max_impl<float, true> 265 { static inline constexpr float value = __FLT_MAX__; }; 266 267 template <> 268 struct __finite_max_impl<double, true> 269 { static inline constexpr double value = __DBL_MAX__; }; 270 271 template <> 272 struct __finite_max_impl<long double, true> 273 { static inline constexpr long double value = __LDBL_MAX__; }; 274 275 template <typename _Tp> 276 struct __infinity_impl {}; 277 278 #if __FLT_HAS_INFINITY__ 279 template <> 280 struct __infinity_impl<float> 281 { static inline constexpr float value = __builtin_inff(); }; 282 #endif 283 284 #if __DBL_HAS_INFINITY__ 285 template <> 286 struct __infinity_impl<double> 287 { static inline constexpr double value = __builtin_inf(); }; 288 #endif 289 290 #if __LDBL_HAS_INFINITY__ 291 template <> 292 struct __infinity_impl<long double> 293 { static inline constexpr long double value = __builtin_infl(); }; 294 #endif 295 296 template <typename _Tp> 297 struct __quiet_NaN_impl {}; 298 299 #if __FLT_HAS_QUIET_NAN__ 300 template <> 301 struct __quiet_NaN_impl<float> 302 { static inline constexpr float value = __builtin_nanf(""); }; 303 #endif 304 305 #if __DBL_HAS_QUIET_NAN__ 306 template <> 307 struct __quiet_NaN_impl<double> 308 { static inline constexpr double value = __builtin_nan(""); }; 309 #endif 310 311 #if __LDBL_HAS_QUIET_NAN__ 312 template <> 313 struct __quiet_NaN_impl<long double> 314 { static inline constexpr long double value = __builtin_nanl(""); }; 315 #endif 316 317 template <typename _Tp, bool = is_floating_point_v<_Tp>> 318 struct __reciprocal_overflow_threshold_impl {}; 319 320 template <typename _Tp> 321 struct __reciprocal_overflow_threshold_impl<_Tp, true> 322 { 323 // This typically yields a subnormal value. Is this incorrect for 324 // flush-to-zero configurations? 325 static constexpr _Tp _S_search(_Tp __ok, _Tp __overflows) 326 { 327 const _Tp __mid = (__ok + __overflows) / 2; 328 // 1/__mid without -ffast-math is not a constant expression if it 329 // overflows. Therefore divide 1 by the radix before division. 330 // Consequently finite_max (the threshold) must be scaled by the 331 // same value. 332 if (__mid == __ok || __mid == __overflows) 333 return __ok; 334 else if (_Tp(1) / (__radix_impl<_Tp>::value * __mid) 335 <= __finite_max_impl<_Tp>::value / __radix_impl<_Tp>::value) 336 return _S_search(__mid, __overflows); 337 else 338 return _S_search(__ok, __mid); 339 } 340 341 static inline constexpr _Tp value 342 = _S_search(_Tp(1.01) / __finite_max_impl<_Tp>::value, 343 _Tp(0.99) / __finite_max_impl<_Tp>::value); 344 }; 345 346 template <typename _Tp, bool = is_floating_point_v<_Tp>> 347 struct __round_error_impl {}; 348 349 template <typename _Tp> 350 struct __round_error_impl<_Tp, true> 351 { static inline constexpr _Tp value = 0.5; }; 352 353 template <typename _Tp> 354 struct __signaling_NaN_impl {}; 355 356 #if __FLT_HAS_QUIET_NAN__ 357 template <> 358 struct __signaling_NaN_impl<float> 359 { static inline constexpr float value = __builtin_nansf(""); }; 360 #endif 361 362 #if __DBL_HAS_QUIET_NAN__ 363 template <> 364 struct __signaling_NaN_impl<double> 365 { static inline constexpr double value = __builtin_nans(""); }; 366 #endif 367 368 #if __LDBL_HAS_QUIET_NAN__ 369 template <> 370 struct __signaling_NaN_impl<long double> 371 { static inline constexpr long double value = __builtin_nansl(""); }; 372 #endif 373 374 // [num.traits.val], numeric distinguished value traits 375 template <typename _Tp> 376 struct __denorm_min : __denorm_min_impl<remove_cv_t<_Tp>> {}; 377 378 template <typename _Tp> 379 struct __epsilon : __epsilon_impl<remove_cv_t<_Tp>> {}; 380 381 template <typename _Tp> 382 struct __finite_max : __finite_max_impl<remove_cv_t<_Tp>> {}; 383 384 template <typename _Tp> 385 struct __finite_min : __finite_min_impl<remove_cv_t<_Tp>> {}; 386 387 template <typename _Tp> 388 struct __infinity : __infinity_impl<remove_cv_t<_Tp>> {}; 389 390 template <typename _Tp> 391 struct __norm_min : __norm_min_impl<remove_cv_t<_Tp>> {}; 392 393 template <typename _Tp> 394 struct __quiet_NaN : __quiet_NaN_impl<remove_cv_t<_Tp>> {}; 395 396 template <typename _Tp> 397 struct __reciprocal_overflow_threshold 398 : __reciprocal_overflow_threshold_impl<remove_cv_t<_Tp>> {}; 399 400 template <typename _Tp> 401 struct __round_error : __round_error_impl<remove_cv_t<_Tp>> {}; 402 403 template <typename _Tp> 404 struct __signaling_NaN : __signaling_NaN_impl<remove_cv_t<_Tp>> {}; 405 406 template <typename _Tp> 407 inline constexpr auto __denorm_min_v = __denorm_min<_Tp>::value; 408 409 template <typename _Tp> 410 inline constexpr auto __epsilon_v = __epsilon<_Tp>::value; 411 412 template <typename _Tp> 413 inline constexpr auto __finite_max_v = __finite_max<_Tp>::value; 414 415 template <typename _Tp> 416 inline constexpr auto __finite_min_v = __finite_min<_Tp>::value; 417 418 template <typename _Tp> 419 inline constexpr auto __infinity_v = __infinity<_Tp>::value; 420 421 template <typename _Tp> 422 inline constexpr auto __norm_min_v = __norm_min<_Tp>::value; 423 424 template <typename _Tp> 425 inline constexpr auto __quiet_NaN_v = __quiet_NaN<_Tp>::value; 426 427 template <typename _Tp> 428 inline constexpr auto __reciprocal_overflow_threshold_v 429 = __reciprocal_overflow_threshold<_Tp>::value; 430 431 template <typename _Tp> 432 inline constexpr auto __round_error_v = __round_error<_Tp>::value; 433 434 template <typename _Tp> 435 inline constexpr auto __signaling_NaN_v = __signaling_NaN<_Tp>::value; 436 437 // [num.traits.char], numeric characteristics traits 438 template <typename _Tp> 439 struct __digits : __digits_impl<remove_cv_t<_Tp>> {}; 440 441 template <typename _Tp> 442 struct __digits10 : __digits10_impl<remove_cv_t<_Tp>> {}; 443 444 template <typename _Tp> 445 struct __max_digits10 : __max_digits10_impl<remove_cv_t<_Tp>> {}; 446 447 template <typename _Tp> 448 struct __max_exponent : __max_exponent_impl<remove_cv_t<_Tp>> {}; 449 450 template <typename _Tp> 451 struct __max_exponent10 : __max_exponent10_impl<remove_cv_t<_Tp>> {}; 452 453 template <typename _Tp> 454 struct __min_exponent : __min_exponent_impl<remove_cv_t<_Tp>> {}; 455 456 template <typename _Tp> 457 struct __min_exponent10 : __min_exponent10_impl<remove_cv_t<_Tp>> {}; 458 459 template <typename _Tp> 460 struct __radix : __radix_impl<remove_cv_t<_Tp>> {}; 461 462 template <typename _Tp> 463 inline constexpr auto __digits_v = __digits<_Tp>::value; 464 465 template <typename _Tp> 466 inline constexpr auto __digits10_v = __digits10<_Tp>::value; 467 468 template <typename _Tp> 469 inline constexpr auto __max_digits10_v = __max_digits10<_Tp>::value; 470 471 template <typename _Tp> 472 inline constexpr auto __max_exponent_v = __max_exponent<_Tp>::value; 473 474 template <typename _Tp> 475 inline constexpr auto __max_exponent10_v = __max_exponent10<_Tp>::value; 476 477 template <typename _Tp> 478 inline constexpr auto __min_exponent_v = __min_exponent<_Tp>::value; 479 480 template <typename _Tp> 481 inline constexpr auto __min_exponent10_v = __min_exponent10<_Tp>::value; 482 483 template <typename _Tp> 484 inline constexpr auto __radix_v = __radix<_Tp>::value; 485 486 // mkretz's extensions 487 // TODO: does GCC tell me? __GCC_IEC_559 >= 2 is not the right answer 488 template <typename _Tp> 489 struct __has_iec559_storage_format : true_type {}; 490 491 template <typename _Tp> 492 inline constexpr bool __has_iec559_storage_format_v 493 = __has_iec559_storage_format<_Tp>::value; 494 495 /* To propose: 496 If __has_iec559_behavior<__quiet_NaN, T> is true the following holds: 497 - nan == nan is false 498 - isnan(nan) is true 499 - isnan(nan + x) is true 500 - isnan(inf/inf) is true 501 - isnan(0/0) is true 502 - isunordered(nan, x) is true 503 504 If __has_iec559_behavior<__infinity, T> is true the following holds (x is 505 neither nan nor inf): 506 - isinf(inf) is true 507 - isinf(inf + x) is true 508 - isinf(1/0) is true 509 */ 510 template <template <typename> class _Trait, typename _Tp> 511 struct __has_iec559_behavior : false_type {}; 512 513 template <template <typename> class _Trait, typename _Tp> 514 inline constexpr bool __has_iec559_behavior_v 515 = __has_iec559_behavior<_Trait, _Tp>::value; 516 517 #if !__FINITE_MATH_ONLY__ 518 #if __FLT_HAS_QUIET_NAN__ 519 template <> 520 struct __has_iec559_behavior<__quiet_NaN, float> : true_type {}; 521 #endif 522 523 #if __DBL_HAS_QUIET_NAN__ 524 template <> 525 struct __has_iec559_behavior<__quiet_NaN, double> : true_type {}; 526 #endif 527 528 #if __LDBL_HAS_QUIET_NAN__ 529 template <> 530 struct __has_iec559_behavior<__quiet_NaN, long double> : true_type {}; 531 #endif 532 533 #if __FLT_HAS_INFINITY__ 534 template <> 535 struct __has_iec559_behavior<__infinity, float> : true_type {}; 536 #endif 537 538 #if __DBL_HAS_INFINITY__ 539 template <> 540 struct __has_iec559_behavior<__infinity, double> : true_type {}; 541 #endif 542 543 #if __LDBL_HAS_INFINITY__ 544 template <> 545 struct __has_iec559_behavior<__infinity, long double> : true_type {}; 546 #endif 547 548 #ifdef __SUPPORT_SNAN__ 549 #if __FLT_HAS_QUIET_NAN__ 550 template <> 551 struct __has_iec559_behavior<__signaling_NaN, float> : true_type {}; 552 #endif 553 554 #if __DBL_HAS_QUIET_NAN__ 555 template <> 556 struct __has_iec559_behavior<__signaling_NaN, double> : true_type {}; 557 #endif 558 559 #if __LDBL_HAS_QUIET_NAN__ 560 template <> 561 struct __has_iec559_behavior<__signaling_NaN, long double> : true_type {}; 562 #endif 563 564 #endif 565 #endif // __FINITE_MATH_ONLY__ 566 567 } // namespace std 568