1 // Primitive numeric conversions (to_chars and from_chars) -*- C++ -*-
3 // Copyright (C) 2017-2021 Free Software Foundation, Inc.
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)
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.
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.
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/>.
25 /** @file include/charconv
26 * This is a Standard C++ Library header.
29 #ifndef _GLIBCXX_CHARCONV
30 #define _GLIBCXX_CHARCONV 1
32 #pragma GCC system_header
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
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>
47 #if _GLIBCXX_HAVE_USELOCALE
48 # define __cpp_lib_to_chars 201611L
51 namespace std _GLIBCXX_VISIBILITY(default)
53 _GLIBCXX_BEGIN_NAMESPACE_VERSION
55 /// Result type of std::to_chars
56 struct to_chars_result
61 #if __cplusplus > 201703L && __cpp_impl_three_way_comparison >= 201907L
63 operator==(const to_chars_result&, const to_chars_result&) = default;
67 /// Result type of std::from_chars
68 struct from_chars_result
73 #if __cplusplus > 201703L && __cpp_impl_three_way_comparison >= 201907L
75 operator==(const from_chars_result&, const from_chars_result&) = default;
81 template<typename _Tp>
82 using __integer_to_chars_result_type
83 = enable_if_t<__or_<__is_signed_integer<_Tp>,
84 __is_unsigned_integer<_Tp>,
85 is_same<char, remove_cv_t<_Tp>>>::value,
88 // Pick an unsigned type of suitable size. This is used to reduce the
89 // number of specializations of __to_chars_len, __to_chars etc. that
90 // get instantiated. For example, to_chars<char> and to_chars<short>
91 // and to_chars<unsigned> will all use the same code, and so will
92 // to_chars<long> when sizeof(int) == sizeof(long).
93 template<typename _Tp>
94 struct __to_chars_unsigned_type : __make_unsigned_selector_base
96 using _UInts = _List<unsigned int, unsigned long, unsigned long long
97 #if _GLIBCXX_USE_INT128
101 using type = typename __select<sizeof(_Tp), _UInts>::__type;
104 template<typename _Tp>
105 using __unsigned_least_t = typename __to_chars_unsigned_type<_Tp>::type;
107 // Generic implementation for arbitrary bases.
108 // Defined in <bits/charconv.h>.
109 template<typename _Tp>
111 __to_chars_len(_Tp __value, int __base /* = 10 */) noexcept;
113 template<typename _Tp>
115 __to_chars_len_2(_Tp __value) noexcept
116 { return std::__bit_width(__value); }
118 // Generic implementation for arbitrary bases.
119 template<typename _Tp>
121 __to_chars(char* __first, char* __last, _Tp __val, int __base) noexcept
123 static_assert(is_integral<_Tp>::value, "implementation bug");
124 static_assert(is_unsigned<_Tp>::value, "implementation bug");
126 to_chars_result __res;
128 const unsigned __len = __to_chars_len(__val, __base);
130 if (__builtin_expect((__last - __first) < __len, 0))
133 __res.ec = errc::value_too_large;
137 unsigned __pos = __len - 1;
139 static constexpr char __digits[] = {
140 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
141 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
142 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
143 'u', 'v', 'w', 'x', 'y', 'z'
146 while (__val >= (unsigned)__base)
148 auto const __quo = __val / __base;
149 auto const __rem = __val % __base;
150 __first[__pos--] = __digits[__rem];
153 *__first = __digits[__val];
155 __res.ptr = __first + __len;
160 template<typename _Tp>
161 __integer_to_chars_result_type<_Tp>
162 __to_chars_16(char* __first, char* __last, _Tp __val) noexcept
164 static_assert(is_integral<_Tp>::value, "implementation bug");
165 static_assert(is_unsigned<_Tp>::value, "implementation bug");
167 to_chars_result __res;
169 const unsigned __len = (__to_chars_len_2(__val) + 3) / 4;
171 if (__builtin_expect((__last - __first) < __len, 0))
174 __res.ec = errc::value_too_large;
178 static constexpr char __digits[] = {
179 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
180 'a', 'b', 'c', 'd', 'e', 'f'
182 unsigned __pos = __len - 1;
183 while (__val >= 0x100)
185 auto __num = __val & 0xF;
187 __first[__pos] = __digits[__num];
190 __first[__pos - 1] = __digits[__num];
195 const auto __num = __val & 0xF;
197 __first[1] = __digits[__num];
198 __first[0] = __digits[__val];
201 __first[0] = __digits[__val];
202 __res.ptr = __first + __len;
207 template<typename _Tp>
208 inline __integer_to_chars_result_type<_Tp>
209 __to_chars_10(char* __first, char* __last, _Tp __val) noexcept
211 static_assert(is_integral<_Tp>::value, "implementation bug");
212 static_assert(is_unsigned<_Tp>::value, "implementation bug");
214 to_chars_result __res;
216 const unsigned __len = __to_chars_len(__val, 10);
218 if (__builtin_expect((__last - __first) < __len, 0))
221 __res.ec = errc::value_too_large;
225 __detail::__to_chars_10_impl(__first, __len, __val);
226 __res.ptr = __first + __len;
231 template<typename _Tp>
232 __integer_to_chars_result_type<_Tp>
233 __to_chars_8(char* __first, char* __last, _Tp __val) noexcept
235 static_assert(is_integral<_Tp>::value, "implementation bug");
236 static_assert(is_unsigned<_Tp>::value, "implementation bug");
238 to_chars_result __res;
241 if _GLIBCXX17_CONSTEXPR (__gnu_cxx::__int_traits<_Tp>::__digits <= 16)
243 __len = __val > 077777u ? 6u
244 : __val > 07777u ? 5u
251 __len = (__to_chars_len_2(__val) + 2) / 3;
253 if (__builtin_expect((__last - __first) < __len, 0))
256 __res.ec = errc::value_too_large;
260 unsigned __pos = __len - 1;
261 while (__val >= 0100)
263 auto __num = __val & 7;
265 __first[__pos] = '0' + __num;
268 __first[__pos - 1] = '0' + __num;
273 auto const __num = __val & 7;
275 __first[1] = '0' + __num;
276 __first[0] = '0' + __val;
279 __first[0] = '0' + __val;
280 __res.ptr = __first + __len;
285 template<typename _Tp>
286 __integer_to_chars_result_type<_Tp>
287 __to_chars_2(char* __first, char* __last, _Tp __val) noexcept
289 static_assert(is_integral<_Tp>::value, "implementation bug");
290 static_assert(is_unsigned<_Tp>::value, "implementation bug");
292 to_chars_result __res;
294 const unsigned __len = __to_chars_len_2(__val);
296 if (__builtin_expect((__last - __first) < __len, 0))
299 __res.ec = errc::value_too_large;
303 unsigned __pos = __len - 1;
307 __first[__pos--] = '0' + (__val & 1);
310 // First digit is always '1' because __to_chars_len_2 skips
311 // leading zero bits and std::to_chars handles zero values
315 __res.ptr = __first + __len;
320 } // namespace __detail
322 template<typename _Tp>
323 __detail::__integer_to_chars_result_type<_Tp>
324 __to_chars_i(char* __first, char* __last, _Tp __value, int __base = 10)
326 __glibcxx_assert(2 <= __base && __base <= 36);
328 using _Up = __detail::__unsigned_least_t<_Tp>;
329 _Up __unsigned_val = __value;
331 if (__first == __last) [[__unlikely__]]
332 return { __last, errc::value_too_large };
337 return { __first + 1, errc{} };
339 else if _GLIBCXX17_CONSTEXPR (std::is_signed<_Tp>::value)
343 __unsigned_val = _Up(~__value) + _Up(1);
349 return __detail::__to_chars_16(__first, __last, __unsigned_val);
351 return __detail::__to_chars_10(__first, __last, __unsigned_val);
353 return __detail::__to_chars_8(__first, __last, __unsigned_val);
355 return __detail::__to_chars_2(__first, __last, __unsigned_val);
357 return __detail::__to_chars(__first, __last, __unsigned_val, __base);
361 #define _GLIBCXX_TO_CHARS(T) \
362 inline to_chars_result \
363 to_chars(char* __first, char* __last, T __value, int __base = 10) \
364 { return std::__to_chars_i<T>(__first, __last, __value, __base); }
365 _GLIBCXX_TO_CHARS(char)
366 _GLIBCXX_TO_CHARS(signed char)
367 _GLIBCXX_TO_CHARS(unsigned char)
368 _GLIBCXX_TO_CHARS(signed short)
369 _GLIBCXX_TO_CHARS(unsigned short)
370 _GLIBCXX_TO_CHARS(signed int)
371 _GLIBCXX_TO_CHARS(unsigned int)
372 _GLIBCXX_TO_CHARS(signed long)
373 _GLIBCXX_TO_CHARS(unsigned long)
374 _GLIBCXX_TO_CHARS(signed long long)
375 _GLIBCXX_TO_CHARS(unsigned long long)
376 #if defined(__GLIBCXX_TYPE_INT_N_0)
377 _GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_0)
378 _GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_0)
380 #if defined(__GLIBCXX_TYPE_INT_N_1)
381 _GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_1)
382 _GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_1)
384 #if defined(__GLIBCXX_TYPE_INT_N_2)
385 _GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_2)
386 _GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_2)
388 #if defined(__GLIBCXX_TYPE_INT_N_3)
389 _GLIBCXX_TO_CHARS(signed __GLIBCXX_TYPE_INT_N_3)
390 _GLIBCXX_TO_CHARS(unsigned __GLIBCXX_TYPE_INT_N_3)
392 #undef _GLIBCXX_TO_CHARS
394 // _GLIBCXX_RESOLVE_LIB_DEFECTS
395 // 3266. to_chars(bool) should be deleted
396 to_chars_result to_chars(char*, char*, bool, int = 10) = delete;
400 template<typename _Tp>
402 __raise_and_add(_Tp& __val, int __base, unsigned char __c)
404 if (__builtin_mul_overflow(__val, __base, &__val)
405 || __builtin_add_overflow(__val, __c, &__val))
410 /// std::from_chars implementation for integers in base 2.
411 template<typename _Tp>
413 __from_chars_binary(const char*& __first, const char* __last, _Tp& __val)
415 static_assert(is_integral<_Tp>::value, "implementation bug");
416 static_assert(is_unsigned<_Tp>::value, "implementation bug");
418 const ptrdiff_t __len = __last - __first;
420 while (__i < __len && __first[__i] == '0')
422 const ptrdiff_t __leading_zeroes = __i;
426 const unsigned char __c = (unsigned)__first[__i] - '0';
428 __val = (__val << 1) | __c;
434 return (__i - __leading_zeroes) <= __gnu_cxx::__int_traits<_Tp>::__digits;
437 /// std::from_chars implementation for integers in bases 3 to 10.
438 template<typename _Tp>
440 __from_chars_digit(const char*& __first, const char* __last, _Tp& __val,
443 static_assert(is_integral<_Tp>::value, "implementation bug");
444 static_assert(is_unsigned<_Tp>::value, "implementation bug");
446 auto __matches = [__base](char __c) {
447 return '0' <= __c && __c <= ('0' + (__base - 1));
450 while (__first != __last)
452 const char __c = *__first;
455 if (!__raise_and_add(__val, __base, __c - '0'))
457 while (++__first != __last && __matches(*__first))
469 constexpr unsigned char
470 __from_chars_alpha_to_num(char __c)
553 return __gnu_cxx::__int_traits<unsigned char>::__max;
556 /// std::from_chars implementation for integers in bases 11 to 26.
557 template<typename _Tp>
559 __from_chars_alnum(const char*& __first, const char* __last, _Tp& __val,
563 while (__first != __last)
565 unsigned char __c = *__first;
566 if (std::isdigit(__c))
570 __c = __from_chars_alpha_to_num(__c);
575 if (__builtin_expect(__valid, 1))
576 __valid = __raise_and_add(__val, __base, __c);
582 template<typename _Tp>
583 using __integer_from_chars_result_type
584 = enable_if_t<__or_<__is_signed_integer<_Tp>,
585 __is_unsigned_integer<_Tp>,
586 is_same<char, remove_cv_t<_Tp>>>::value,
589 } // namespace __detail
591 /// std::from_chars for integral types.
592 template<typename _Tp>
593 __detail::__integer_from_chars_result_type<_Tp>
594 from_chars(const char* __first, const char* __last, _Tp& __value,
597 __glibcxx_assert(2 <= __base && __base <= 36);
599 from_chars_result __res{__first, {}};
602 if _GLIBCXX17_CONSTEXPR (std::is_signed<_Tp>::value)
603 if (__first != __last && *__first == '-')
609 using _Up = __detail::__unsigned_least_t<_Tp>;
612 const auto __start = __first;
615 __valid = __detail::__from_chars_binary(__first, __last, __val);
616 else if (__base <= 10)
617 __valid = __detail::__from_chars_digit(__first, __last, __val, __base);
619 __valid = __detail::__from_chars_alnum(__first, __last, __val, __base);
621 if (__builtin_expect(__first == __start, 0))
622 __res.ec = errc::invalid_argument;
627 __res.ec = errc::result_out_of_range;
630 if _GLIBCXX17_CONSTEXPR (std::is_signed<_Tp>::value)
633 if (__builtin_mul_overflow(__val, __sign, &__tmp))
634 __res.ec = errc::result_out_of_range;
640 if _GLIBCXX17_CONSTEXPR (__gnu_cxx::__int_traits<_Up>::__max
641 > __gnu_cxx::__int_traits<_Tp>::__max)
643 if (__val > __gnu_cxx::__int_traits<_Tp>::__max)
644 __res.ec = errc::result_out_of_range;
656 /// floating-point format for primitive numerical conversion
657 enum class chars_format
659 scientific = 1, fixed = 2, hex = 4, general = fixed | scientific
662 constexpr chars_format
663 operator|(chars_format __lhs, chars_format __rhs) noexcept
664 { return (chars_format)((unsigned)__lhs | (unsigned)__rhs); }
666 constexpr chars_format
667 operator&(chars_format __lhs, chars_format __rhs) noexcept
668 { return (chars_format)((unsigned)__lhs & (unsigned)__rhs); }
670 constexpr chars_format
671 operator^(chars_format __lhs, chars_format __rhs) noexcept
672 { return (chars_format)((unsigned)__lhs ^ (unsigned)__rhs); }
674 constexpr chars_format
675 operator~(chars_format __fmt) noexcept
676 { return (chars_format)~(unsigned)__fmt; }
678 constexpr chars_format&
679 operator|=(chars_format& __lhs, chars_format __rhs) noexcept
680 { return __lhs = __lhs | __rhs; }
682 constexpr chars_format&
683 operator&=(chars_format& __lhs, chars_format __rhs) noexcept
684 { return __lhs = __lhs & __rhs; }
686 constexpr chars_format&
687 operator^=(chars_format& __lhs, chars_format __rhs) noexcept
688 { return __lhs = __lhs ^ __rhs; }
690 #if _GLIBCXX_HAVE_USELOCALE
692 from_chars(const char* __first, const char* __last, float& __value,
693 chars_format __fmt = chars_format::general) noexcept;
696 from_chars(const char* __first, const char* __last, double& __value,
697 chars_format __fmt = chars_format::general) noexcept;
700 from_chars(const char* __first, const char* __last, long double& __value,
701 chars_format __fmt = chars_format::general) noexcept;
704 #if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 \
705 && __SIZE_WIDTH__ >= 32
706 // Floating-point std::to_chars
708 // Overloads for float.
709 to_chars_result to_chars(char* __first, char* __last, float __value) noexcept;
710 to_chars_result to_chars(char* __first, char* __last, float __value,
711 chars_format __fmt) noexcept;
712 to_chars_result to_chars(char* __first, char* __last, float __value,
713 chars_format __fmt, int __precision) noexcept;
715 // Overloads for double.
716 to_chars_result to_chars(char* __first, char* __last, double __value) noexcept;
717 to_chars_result to_chars(char* __first, char* __last, double __value,
718 chars_format __fmt) noexcept;
719 to_chars_result to_chars(char* __first, char* __last, double __value,
720 chars_format __fmt, int __precision) noexcept;
722 // Overloads for long double.
723 to_chars_result to_chars(char* __first, char* __last, long double __value)
725 to_chars_result to_chars(char* __first, char* __last, long double __value,
726 chars_format __fmt) noexcept;
727 to_chars_result to_chars(char* __first, char* __last, long double __value,
728 chars_format __fmt, int __precision) noexcept;
731 _GLIBCXX_END_NAMESPACE_VERSION
734 #endif // _GLIBCXX_CHARCONV