1// Primitive numeric conversions (to_chars and from_chars) -*- C++ -*- 2 3// Copyright (C) 2017-2020 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/** @file include/charconv 26 * This is a Standard C++ Library header. 27 */ 28 29#ifndef _GLIBCXX_CHARCONV 30#define _GLIBCXX_CHARCONV 1 31 32#pragma GCC system_header 33 34// As an extension we support <charconv> in C++14, but this header should not 35// be included by any other library headers in C++14 mode. This ensures that 36// the names defined in this header are not added to namespace std unless a 37// user explicitly includes <charconv> in C++14 code. 38#if __cplusplus >= 201402L 39 40#include <type_traits> 41#include <bit> // for __bit_width 42#include <cctype> // for isdigit 43#include <bits/charconv.h> // for __to_chars_len, __to_chars_10_impl 44#include <bits/error_constants.h> // for std::errc 45#include <ext/numeric_traits.h> 46 47// FIXME: Define when floating point is supported: 48// #define __cpp_lib_to_chars 201611L 49 50namespace std _GLIBCXX_VISIBILITY(default) 51{ 52_GLIBCXX_BEGIN_NAMESPACE_VERSION 53 54 /// Result type of std::to_chars 55 struct to_chars_result 56 { 57 char* ptr; 58 errc ec; 59 60#if __cplusplus > 201703L && __cpp_impl_three_way_comparison >= 201907L 61 friend bool 62 operator==(const to_chars_result&, const to_chars_result&) = default; 63#endif 64 }; 65 66 /// Result type of std::from_chars 67 struct from_chars_result 68 { 69 const char* ptr; 70 errc ec; 71 72#if __cplusplus > 201703L && __cpp_impl_three_way_comparison >= 201907L 73 friend bool 74 operator==(const from_chars_result&, const from_chars_result&) = default; 75#endif 76 }; 77 78namespace __detail 79{ 80 template<typename _Tp> 81 using __integer_to_chars_result_type 82 = enable_if_t<__or_<__is_signed_integer<_Tp>, 83 __is_unsigned_integer<_Tp>, 84 is_same<char, remove_cv_t<_Tp>>>::value, 85 to_chars_result>; 86 87 // Pick an unsigned type of suitable size. This is used to reduce the 88 // number of specializations of __to_chars_len, __to_chars etc. that 89 // get instantiated. For example, to_chars<char> and to_chars<short> 90 // and to_chars<unsigned> will all use the same code, and so will 91 // to_chars<long> when sizeof(int) == sizeof(long). 92 template<typename _Tp> 93 struct __to_chars_unsigned_type : __make_unsigned_selector_base 94 { 95 using _UInts = _List<unsigned int, unsigned long, unsigned long long 96#if _GLIBCXX_USE_INT128 97 , unsigned __int128 98#endif 99 >; 100 using type = typename __select<sizeof(_Tp), _UInts>::__type; 101 }; 102 103 template<typename _Tp> 104 using __unsigned_least_t = typename __to_chars_unsigned_type<_Tp>::type; 105 106 // Generic implementation for arbitrary bases. 107 // Defined in <bits/charconv.h>. 108 template<typename _Tp> 109 constexpr unsigned 110 __to_chars_len(_Tp __value, int __base /* = 10 */) noexcept; 111 112 template<typename _Tp> 113 constexpr unsigned 114 __to_chars_len_2(_Tp __value) noexcept 115 { return std::__bit_width(__value); } 116 117 // Generic implementation for arbitrary bases. 118 template<typename _Tp> 119 to_chars_result 120 __to_chars(char* __first, char* __last, _Tp __val, int __base) noexcept 121 { 122 static_assert(is_integral<_Tp>::value, "implementation bug"); 123 static_assert(is_unsigned<_Tp>::value, "implementation bug"); 124 125 to_chars_result __res; 126 127 const unsigned __len = __to_chars_len(__val, __base); 128 129 if (__builtin_expect((__last - __first) < __len, 0)) 130 { 131 __res.ptr = __last; 132 __res.ec = errc::value_too_large; 133 return __res; 134 } 135 136 unsigned __pos = __len - 1; 137 138 static constexpr char __digits[] = { 139 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 140 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 141 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 142 'u', 'v', 'w', 'x', 'y', 'z' 143 }; 144 145 while (__val >= (unsigned)__base) 146 { 147 auto const __quo = __val / __base; 148 auto const __rem = __val % __base; 149 __first[__pos--] = __digits[__rem]; 150 __val = __quo; 151 } 152 *__first = __digits[__val]; 153 154 __res.ptr = __first + __len; 155 __res.ec = {}; 156 return __res; 157 } 158 159 template<typename _Tp> 160 __integer_to_chars_result_type<_Tp> 161 __to_chars_16(char* __first, char* __last, _Tp __val) noexcept 162 { 163 static_assert(is_integral<_Tp>::value, "implementation bug"); 164 static_assert(is_unsigned<_Tp>::value, "implementation bug"); 165 166 to_chars_result __res; 167 168 const unsigned __len = (__to_chars_len_2(__val) + 3) / 4; 169 170 if (__builtin_expect((__last - __first) < __len, 0)) 171 { 172 __res.ptr = __last; 173 __res.ec = errc::value_too_large; 174 return __res; 175 } 176 177 static constexpr char __digits[] = { 178 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 179 'a', 'b', 'c', 'd', 'e', 'f' 180 }; 181 unsigned __pos = __len - 1; 182 while (__val >= 0x100) 183 { 184 auto __num = __val & 0xF; 185 __val >>= 4; 186 __first[__pos] = __digits[__num]; 187 __num = __val & 0xF; 188 __val >>= 4; 189 __first[__pos - 1] = __digits[__num]; 190 __pos -= 2; 191 } 192 if (__val >= 0x10) 193 { 194 const auto __num = __val & 0xF; 195 __val >>= 4; 196 __first[1] = __digits[__num]; 197 __first[0] = __digits[__val]; 198 } 199 else 200 __first[0] = __digits[__val]; 201 __res.ptr = __first + __len; 202 __res.ec = {}; 203 return __res; 204 } 205 206 template<typename _Tp> 207 inline __integer_to_chars_result_type<_Tp> 208 __to_chars_10(char* __first, char* __last, _Tp __val) noexcept 209 { 210 static_assert(is_integral<_Tp>::value, "implementation bug"); 211 static_assert(is_unsigned<_Tp>::value, "implementation bug"); 212 213 to_chars_result __res; 214 215 const unsigned __len = __to_chars_len(__val, 10); 216 217 if (__builtin_expect((__last - __first) < __len, 0)) 218 { 219 __res.ptr = __last; 220 __res.ec = errc::value_too_large; 221 return __res; 222 } 223 224 __detail::__to_chars_10_impl(__first, __len, __val); 225 __res.ptr = __first + __len; 226 __res.ec = {}; 227 return __res; 228 } 229 230 template<typename _Tp> 231 __integer_to_chars_result_type<_Tp> 232 __to_chars_8(char* __first, char* __last, _Tp __val) noexcept 233 { 234 static_assert(is_integral<_Tp>::value, "implementation bug"); 235 static_assert(is_unsigned<_Tp>::value, "implementation bug"); 236 237 to_chars_result __res; 238 unsigned __len; 239 240 if _GLIBCXX17_CONSTEXPR (__gnu_cxx::__int_traits<_Tp>::__digits <= 16) 241 { 242 __len = __val > 077777u ? 6u 243 : __val > 07777u ? 5u 244 : __val > 0777u ? 4u 245 : __val > 077u ? 3u 246 : __val > 07u ? 2u 247 : 1u; 248 } 249 else 250 __len = (__to_chars_len_2(__val) + 2) / 3; 251 252 if (__builtin_expect((__last - __first) < __len, 0)) 253 { 254 __res.ptr = __last; 255 __res.ec = errc::value_too_large; 256 return __res; 257 } 258 259 unsigned __pos = __len - 1; 260 while (__val >= 0100) 261 { 262 auto __num = __val & 7; 263 __val >>= 3; 264 __first[__pos] = '0' + __num; 265 __num = __val & 7; 266 __val >>= 3; 267 __first[__pos - 1] = '0' + __num; 268 __pos -= 2; 269 } 270 if (__val >= 010) 271 { 272 auto const __num = __val & 7; 273 __val >>= 3; 274 __first[1] = '0' + __num; 275 __first[0] = '0' + __val; 276 } 277 else 278 __first[0] = '0' + __val; 279 __res.ptr = __first + __len; 280 __res.ec = {}; 281 return __res; 282 } 283 284 template<typename _Tp> 285 __integer_to_chars_result_type<_Tp> 286 __to_chars_2(char* __first, char* __last, _Tp __val) noexcept 287 { 288 static_assert(is_integral<_Tp>::value, "implementation bug"); 289 static_assert(is_unsigned<_Tp>::value, "implementation bug"); 290 291 to_chars_result __res; 292 293 const unsigned __len = __to_chars_len_2(__val); 294 295 if (__builtin_expect((__last - __first) < __len, 0)) 296 { 297 __res.ptr = __last; 298 __res.ec = errc::value_too_large; 299 return __res; 300 } 301 302 unsigned __pos = __len - 1; 303 304 while (__pos) 305 { 306 __first[__pos--] = '0' + (__val & 1); 307 __val >>= 1; 308 } 309 // First digit is always '1' because __to_chars_len_2 skips 310 // leading zero bits and std::to_chars handles zero values 311 // directly. 312 __first[0] = '1'; 313 314 __res.ptr = __first + __len; 315 __res.ec = {}; 316 return __res; 317 } 318 319} // namespace __detail 320 321 template<typename _Tp> 322 __detail::__integer_to_chars_result_type<_Tp> 323 __to_chars_i(char* __first, char* __last, _Tp __value, int __base = 10) 324 { 325 __glibcxx_assert(2 <= __base && __base <= 36); 326 327 using _Up = __detail::__unsigned_least_t<_Tp>; 328 _Up __unsigned_val = __value; 329 330 if (__first == __last) [[__unlikely__]] 331 return { __last, errc::value_too_large }; 332 333 if (__value == 0) 334 { 335 *__first = '0'; 336 return { __first + 1, errc{} }; 337 } 338 339 if _GLIBCXX17_CONSTEXPR (std::is_signed<_Tp>::value) 340 if (__value < 0) 341 { 342 if (__builtin_expect(__first != __last, 1)) 343 *__first++ = '-'; 344 __unsigned_val = _Up(~__value) + _Up(1); 345 } 346 347 switch (__base) 348 { 349 case 16: 350 return __detail::__to_chars_16(__first, __last, __unsigned_val); 351 case 10: 352 return __detail::__to_chars_10(__first, __last, __unsigned_val); 353 case 8: 354 return __detail::__to_chars_8(__first, __last, __unsigned_val); 355 case 2: 356 return __detail::__to_chars_2(__first, __last, __unsigned_val); 357 default: 358 return __detail::__to_chars(__first, __last, __unsigned_val, __base); 359 } 360 } 361 362#define _GLIBCXX_TO_CHARS(T) \ 363 inline to_chars_result \ 364 to_chars(char* __first, char* __last, T __value, int __base = 10) \ 365 { return std::__to_chars_i<T>(__first, __last, __value, __base); } 366_GLIBCXX_TO_CHARS(char) 367_GLIBCXX_TO_CHARS(signed char) 368_GLIBCXX_TO_CHARS(unsigned char) 369_GLIBCXX_TO_CHARS(signed short) 370_GLIBCXX_TO_CHARS(unsigned short) 371_GLIBCXX_TO_CHARS(signed int) 372_GLIBCXX_TO_CHARS(unsigned int) 373_GLIBCXX_TO_CHARS(signed long) 374_GLIBCXX_TO_CHARS(unsigned long) 375_GLIBCXX_TO_CHARS(signed long long) 376_GLIBCXX_TO_CHARS(unsigned long long) 377#if defined(__GLIBCXX_TYPE_INT_N_0) 378_GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_0) 379_GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_0) 380#endif 381#if defined(__GLIBCXX_TYPE_INT_N_1) 382_GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_1) 383_GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_1) 384#endif 385#if defined(__GLIBCXX_TYPE_INT_N_2) 386_GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_2) 387_GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_2) 388#endif 389#if defined(__GLIBCXX_TYPE_INT_N_3) 390_GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_3) 391_GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_3) 392#endif 393#undef _GLIBCXX_TO_CHARS 394 395 // _GLIBCXX_RESOLVE_LIB_DEFECTS 396 // 3266. to_chars(bool) should be deleted 397 to_chars_result to_chars(char*, char*, bool, int = 10) = delete; 398 399namespace __detail 400{ 401 template<typename _Tp> 402 bool 403 __raise_and_add(_Tp& __val, int __base, unsigned char __c) 404 { 405 if (__builtin_mul_overflow(__val, __base, &__val) 406 || __builtin_add_overflow(__val, __c, &__val)) 407 return false; 408 return true; 409 } 410 411 /// std::from_chars implementation for integers in base 2. 412 template<typename _Tp> 413 bool 414 __from_chars_binary(const char*& __first, const char* __last, _Tp& __val) 415 { 416 static_assert(is_integral<_Tp>::value, "implementation bug"); 417 static_assert(is_unsigned<_Tp>::value, "implementation bug"); 418 419 const ptrdiff_t __len = __last - __first; 420 ptrdiff_t __i = 0; 421 while (__i < __len && __first[__i] == '0') 422 ++__i; 423 const ptrdiff_t __leading_zeroes = __i; 424 425 while (__i < __len) 426 { 427 const unsigned char __c = (unsigned)__first[__i] - '0'; 428 if (__c < 2) 429 __val = (__val << 1) | __c; 430 else 431 break; 432 __i++; 433 } 434 __first += __i; 435 return (__i - __leading_zeroes) <= __gnu_cxx::__int_traits<_Tp>::__digits; 436 } 437 438 /// std::from_chars implementation for integers in bases 3 to 10. 439 template<typename _Tp> 440 bool 441 __from_chars_digit(const char*& __first, const char* __last, _Tp& __val, 442 int __base) 443 { 444 static_assert(is_integral<_Tp>::value, "implementation bug"); 445 static_assert(is_unsigned<_Tp>::value, "implementation bug"); 446 447 auto __matches = [__base](char __c) { 448 return '0' <= __c && __c <= ('0' + (__base - 1)); 449 }; 450 451 while (__first != __last) 452 { 453 const char __c = *__first; 454 if (__matches(__c)) 455 { 456 if (!__raise_and_add(__val, __base, __c - '0')) 457 { 458 while (++__first != __last && __matches(*__first)) 459 ; 460 return false; 461 } 462 __first++; 463 } 464 else 465 return true; 466 } 467 return true; 468 } 469 470 constexpr unsigned char 471 __from_chars_alpha_to_num(char __c) 472 { 473 switch (__c) 474 { 475 case 'a': 476 case 'A': 477 return 10; 478 case 'b': 479 case 'B': 480 return 11; 481 case 'c': 482 case 'C': 483 return 12; 484 case 'd': 485 case 'D': 486 return 13; 487 case 'e': 488 case 'E': 489 return 14; 490 case 'f': 491 case 'F': 492 return 15; 493 case 'g': 494 case 'G': 495 return 16; 496 case 'h': 497 case 'H': 498 return 17; 499 case 'i': 500 case 'I': 501 return 18; 502 case 'j': 503 case 'J': 504 return 19; 505 case 'k': 506 case 'K': 507 return 20; 508 case 'l': 509 case 'L': 510 return 21; 511 case 'm': 512 case 'M': 513 return 22; 514 case 'n': 515 case 'N': 516 return 23; 517 case 'o': 518 case 'O': 519 return 24; 520 case 'p': 521 case 'P': 522 return 25; 523 case 'q': 524 case 'Q': 525 return 26; 526 case 'r': 527 case 'R': 528 return 27; 529 case 's': 530 case 'S': 531 return 28; 532 case 't': 533 case 'T': 534 return 29; 535 case 'u': 536 case 'U': 537 return 30; 538 case 'v': 539 case 'V': 540 return 31; 541 case 'w': 542 case 'W': 543 return 32; 544 case 'x': 545 case 'X': 546 return 33; 547 case 'y': 548 case 'Y': 549 return 34; 550 case 'z': 551 case 'Z': 552 return 35; 553 } 554 return __gnu_cxx::__int_traits<unsigned char>::__max; 555 } 556 557 /// std::from_chars implementation for integers in bases 11 to 26. 558 template<typename _Tp> 559 bool 560 __from_chars_alnum(const char*& __first, const char* __last, _Tp& __val, 561 int __base) 562 { 563 bool __valid = true; 564 while (__first != __last) 565 { 566 unsigned char __c = *__first; 567 if (std::isdigit(__c)) 568 __c -= '0'; 569 else 570 { 571 __c = __from_chars_alpha_to_num(__c); 572 if (__c >= __base) 573 break; 574 } 575 576 if (__builtin_expect(__valid, 1)) 577 __valid = __raise_and_add(__val, __base, __c); 578 __first++; 579 } 580 return __valid; 581 } 582 583 template<typename _Tp> 584 using __integer_from_chars_result_type 585 = enable_if_t<__or_<__is_signed_integer<_Tp>, 586 __is_unsigned_integer<_Tp>, 587 is_same<char, remove_cv_t<_Tp>>>::value, 588 from_chars_result>; 589 590} // namespace __detail 591 592 /// std::from_chars for integral types. 593 template<typename _Tp> 594 __detail::__integer_from_chars_result_type<_Tp> 595 from_chars(const char* __first, const char* __last, _Tp& __value, 596 int __base = 10) 597 { 598 __glibcxx_assert(2 <= __base && __base <= 36); 599 600 from_chars_result __res{__first, {}}; 601 602 int __sign = 1; 603 if _GLIBCXX17_CONSTEXPR (std::is_signed<_Tp>::value) 604 if (__first != __last && *__first == '-') 605 { 606 __sign = -1; 607 ++__first; 608 } 609 610 using _Up = __detail::__unsigned_least_t<_Tp>; 611 _Up __val = 0; 612 613 const auto __start = __first; 614 bool __valid; 615 if (__base == 2) 616 __valid = __detail::__from_chars_binary(__first, __last, __val); 617 else if (__base <= 10) 618 __valid = __detail::__from_chars_digit(__first, __last, __val, __base); 619 else 620 __valid = __detail::__from_chars_alnum(__first, __last, __val, __base); 621 622 if (__builtin_expect(__first == __start, 0)) 623 __res.ec = errc::invalid_argument; 624 else 625 { 626 __res.ptr = __first; 627 if (!__valid) 628 __res.ec = errc::result_out_of_range; 629 else 630 { 631 if _GLIBCXX17_CONSTEXPR (std::is_signed<_Tp>::value) 632 { 633 _Tp __tmp; 634 if (__builtin_mul_overflow(__val, __sign, &__tmp)) 635 __res.ec = errc::result_out_of_range; 636 else 637 __value = __tmp; 638 } 639 else 640 { 641 if _GLIBCXX17_CONSTEXPR (__gnu_cxx::__int_traits<_Up>::__max 642 > __gnu_cxx::__int_traits<_Tp>::__max) 643 { 644 if (__val > __gnu_cxx::__int_traits<_Tp>::__max) 645 __res.ec = errc::result_out_of_range; 646 else 647 __value = __val; 648 } 649 else 650 __value = __val; 651 } 652 } 653 } 654 return __res; 655 } 656 657 /// floating-point format for primitive numerical conversion 658 enum class chars_format 659 { 660 scientific = 1, fixed = 2, hex = 4, general = fixed | scientific 661 }; 662 663 constexpr chars_format 664 operator|(chars_format __lhs, chars_format __rhs) noexcept 665 { return (chars_format)((unsigned)__lhs | (unsigned)__rhs); } 666 667 constexpr chars_format 668 operator&(chars_format __lhs, chars_format __rhs) noexcept 669 { return (chars_format)((unsigned)__lhs & (unsigned)__rhs); } 670 671 constexpr chars_format 672 operator^(chars_format __lhs, chars_format __rhs) noexcept 673 { return (chars_format)((unsigned)__lhs ^ (unsigned)__rhs); } 674 675 constexpr chars_format 676 operator~(chars_format __fmt) noexcept 677 { return (chars_format)~(unsigned)__fmt; } 678 679 constexpr chars_format& 680 operator|=(chars_format& __lhs, chars_format __rhs) noexcept 681 { return __lhs = __lhs | __rhs; } 682 683 constexpr chars_format& 684 operator&=(chars_format& __lhs, chars_format __rhs) noexcept 685 { return __lhs = __lhs & __rhs; } 686 687 constexpr chars_format& 688 operator^=(chars_format& __lhs, chars_format __rhs) noexcept 689 { return __lhs = __lhs ^ __rhs; } 690 691_GLIBCXX_END_NAMESPACE_VERSION 692} // namespace std 693#endif // C++14 694#endif // _GLIBCXX_CHARCONV 695