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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___CHARCONV_FROM_CHARS_INTEGRAL_H
11#define _LIBCPP___CHARCONV_FROM_CHARS_INTEGRAL_H
12
13#include <__algorithm/copy_n.h>
14#include <__assert>
15#include <__charconv/from_chars_result.h>
16#include <__charconv/traits.h>
17#include <__config>
18#include <__memory/addressof.h>
19#include <__system_error/errc.h>
20#include <__type_traits/enable_if.h>
21#include <__type_traits/integral_constant.h>
22#include <__type_traits/is_integral.h>
23#include <__type_traits/is_unsigned.h>
24#include <__type_traits/make_unsigned.h>
25#include <limits>
26
27#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
28# pragma GCC system_header
29#endif
30
31_LIBCPP_PUSH_MACROS
32#include <__undef_macros>
33
34_LIBCPP_BEGIN_NAMESPACE_STD
35
36#if _LIBCPP_STD_VER >= 17
37
38from_chars_result from_chars(const char*, const char*, bool, int = 10) = delete;
39
40template <typename _It, typename _Tp, typename _Fn, typename... _Ts>
41inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
42__sign_combinator(_It __first, _It __last, _Tp& __value, _Fn __f, _Ts... __args) {
43 using __tl = numeric_limits<_Tp>;
44 decltype(std::__to_unsigned_like(__value)) __x;
45
46 bool __neg = (__first != __last && *__first == '-');
47 auto __r = __f(__neg ? __first + 1 : __first, __last, __x, __args...);
48 switch (__r.ec) {
49 case errc::invalid_argument:
50 return {__first, __r.ec};
51 case errc::result_out_of_range:
52 return __r;
53 default:
54 break;
55 }
56
57 if (__neg) {
58 if (__x <= std::__complement(std::__to_unsigned_like(__tl::min()))) {
59 __x = std::__complement(__x);
60 std::copy_n(std::addressof(__x), 1, std::addressof(__value));
61 return __r;
62 }
63 } else {
64 if (__x <= std::__to_unsigned_like(__tl::max())) {
65 __value = __x;
66 return __r;
67 }
68 }
69
70 return {__r.ptr, errc::result_out_of_range};
71}
72
73template <typename _Tp>
74inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool __in_pattern(_Tp __c) {
75 return '0' <= __c && __c <= '9';
76}
77
78struct _LIBCPP_HIDDEN __in_pattern_result {
79 bool __ok;
80 int __val;
81
82 explicit _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI operator bool() const { return __ok; }
83};
84
85template <typename _Tp>
86inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI __in_pattern_result __in_pattern(_Tp __c, int __base) {
87 if (__base <= 10)
88 return {'0' <= __c && __c < '0' + __base, __c - '0'};
89 else if (std::__in_pattern(__c))
90 return {true, __c - '0'};
91 else if ('a' <= __c && __c < 'a' + __base - 10)
92 return {true, __c - 'a' + 10};
93 else
94 return {'A' <= __c && __c < 'A' + __base - 10, __c - 'A' + 10};
95}
96
97template <typename _It, typename _Tp, typename _Fn, typename... _Ts>
98inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
99__subject_seq_combinator(_It __first, _It __last, _Tp& __value, _Fn __f, _Ts... __args) {
100 auto __find_non_zero = [](_It __firstit, _It __lastit) {
101 for (; __firstit != __lastit; ++__firstit)
102 if (*__firstit != '0')
103 break;
104 return __firstit;
105 };
106
107 auto __p = __find_non_zero(__first, __last);
108 if (__p == __last || !std::__in_pattern(*__p, __args...)) {
109 if (__p == __first)
110 return {__first, errc::invalid_argument};
111 else {
112 __value = 0;
113 return {__p, {}};
114 }
115 }
116
117 auto __r = __f(__p, __last, __value, __args...);
118 if (__r.ec == errc::result_out_of_range) {
119 for (; __r.ptr != __last; ++__r.ptr) {
120 if (!std::__in_pattern(*__r.ptr, __args...))
121 break;
122 }
123 }
124
125 return __r;
126}
127
128template <typename _Tp, __enable_if_t<is_unsigned<_Tp>::value, int> = 0>
129inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
130__from_chars_atoi(const char* __first, const char* __last, _Tp& __value) {
131 using __tx = __itoa::__traits<_Tp>;
132 using __output_type = typename __tx::type;
133
134 return std::__subject_seq_combinator(
135 __first, __last, __value, [](const char* __f, const char* __l, _Tp& __val) -> from_chars_result {
136 __output_type __a, __b;
137 auto __p = __tx::__read(__f, __l, __a, __b);
138 if (__p == __l || !std::__in_pattern(*__p)) {
139 __output_type __m = numeric_limits<_Tp>::max();
140 if (__m >= __a && __m - __a >= __b) {
141 __val = __a + __b;
142 return {__p, {}};
143 }
144 }
145 return {__p, errc::result_out_of_range};
146 });
147}
148
149template <typename _Tp, __enable_if_t<is_signed<_Tp>::value, int> = 0>
150inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
151__from_chars_atoi(const char* __first, const char* __last, _Tp& __value) {
152 using __t = decltype(std::__to_unsigned_like(__value));
153 return std::__sign_combinator(__first, __last, __value, __from_chars_atoi<__t>);
154}
155
156/*
157// Code used to generate __from_chars_log2f_lut.
158#include <cmath>
159#include <format>
160#include <iostream>
161
162int main() {
163 for (int i = 2; i <= 36; ++i)
164 std::cout << std::format("{},\n", log2f(i));
165}
166*/
167/// log2f table for bases [2, 36].
168inline constexpr float __from_chars_log2f_lut[35] = {
169 1, 1.5849625, 2, 2.321928, 2.5849626, 2.807355, 3, 3.169925, 3.321928,
170 3.4594316, 3.5849626, 3.7004397, 3.807355, 3.9068906, 4, 4.087463, 4.169925, 4.2479277,
171 4.321928, 4.3923173, 4.4594316, 4.523562, 4.5849624, 4.643856, 4.70044, 4.7548876, 4.807355,
172 4.857981, 4.9068904, 4.9541965, 5, 5.044394, 5.087463, 5.129283, 5.169925};
173
174template <typename _Tp, __enable_if_t<is_unsigned<_Tp>::value, int> = 0>
175inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
176__from_chars_integral(const char* __first, const char* __last, _Tp& __value, int __base) {
177 if (__base == 10)
178 return std::__from_chars_atoi(__first, __last, __value);
179
180 return std::__subject_seq_combinator(
181 __first,
182 __last,
183 __value,
184 [](const char* __p, const char* __lastp, _Tp& __val, int __b) -> from_chars_result {
185 using __tl = numeric_limits<_Tp>;
186 // __base is always between 2 and 36 inclusive.
187 auto __digits = __tl::digits / __from_chars_log2f_lut[__b - 2];
188 _Tp __x = __in_pattern(*__p++, __b).__val, __y = 0;
189
190 for (int __i = 1; __p != __lastp; ++__i, ++__p) {
191 if (auto __c = __in_pattern(*__p, __b)) {
192 if (__i < __digits - 1)
193 __x = __x * __b + __c.__val;
194 else {
195 if (!__itoa::__mul_overflowed(__x, __b, __x))
196 ++__p;
197 __y = __c.__val;
198 break;
199 }
200 } else
201 break;
202 }
203
204 if (__p == __lastp || !__in_pattern(*__p, __b)) {
205 if (__tl::max() - __x >= __y) {
206 __val = __x + __y;
207 return {__p, {}};
208 }
209 }
210 return {__p, errc::result_out_of_range};
211 },
212 __base);
213}
214
215template <typename _Tp, __enable_if_t<is_signed<_Tp>::value, int> = 0>
216inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
217__from_chars_integral(const char* __first, const char* __last, _Tp& __value, int __base) {
218 using __t = decltype(std::__to_unsigned_like(__value));
219 return std::__sign_combinator(__first, __last, __value, __from_chars_integral<__t>, __base);
220}
221
222template <typename _Tp, __enable_if_t<is_integral<_Tp>::value, int> = 0>
223inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
224from_chars(const char* __first, const char* __last, _Tp& __value) {
225 return std::__from_chars_atoi(__first, __last, __value);
226}
227
228template <typename _Tp, __enable_if_t<is_integral<_Tp>::value, int> = 0>
229inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI from_chars_result
230from_chars(const char* __first, const char* __last, _Tp& __value, int __base) {
231 _LIBCPP_ASSERT_UNCATEGORIZED(2 <= __base && __base <= 36, "base not in [2, 36]");
232 return std::__from_chars_integral(__first, __last, __value, __base);
233}
234#endif // _LIBCPP_STD_VER >= 17
235
236_LIBCPP_END_NAMESPACE_STD
237
238_LIBCPP_POP_MACROS
239
240#endif // _LIBCPP___CHARCONV_FROM_CHARS_INTEGRAL_H