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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___FORMAT_FORMATTER_INTEGRAL_H
11#define _LIBCPP___FORMAT_FORMATTER_INTEGRAL_H
12
13#include <__charconv/to_chars_integral.h>
14#include <__charconv/to_chars_result.h>
15#include <__charconv/traits.h>
16#include <__concepts/arithmetic.h>
17#include <__concepts/same_as.h>
18#include <__config>
19#include <__format/concepts.h>
20#include <__format/format_error.h>
21#include <__format/formatter_output.h>
22#include <__format/parser_std_format_spec.h>
23#include <__iterator/concepts.h>
24#include <__iterator/iterator_traits.h>
25#include <__memory/pointer_traits.h>
26#include <__system_error/errc.h>
27#include <__type_traits/make_unsigned.h>
28#include <__utility/unreachable.h>
29#include <array>
30#include <cstdint>
31#include <limits>
32#include <string>
33#include <string_view>
34
35#if _LIBCPP_HAS_LOCALIZATION
36# include <__locale>
37#endif
38
39#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
40# pragma GCC system_header
41#endif
42
43_LIBCPP_PUSH_MACROS
44#include <__undef_macros>
45
46_LIBCPP_BEGIN_NAMESPACE_STD
47
48#if _LIBCPP_STD_VER >= 20
49
50namespace __formatter {
51
52//
53// Generic
54//
55
56template <contiguous_iterator _Iterator>
57 requires same_as<char, iter_value_t<_Iterator>>
58_LIBCPP_HIDE_FROM_ABI inline _Iterator __insert_sign(_Iterator __buf, bool __negative, __format_spec::__sign __sign) {
59 if (__negative)
60 *__buf++ = '-';
61 else
62 switch (__sign) {
63 case __format_spec::__sign::__default:
64 case __format_spec::__sign::__minus:
65 // No sign added.
66 break;
67 case __format_spec::__sign::__plus:
68 *__buf++ = '+';
69 break;
70 case __format_spec::__sign::__space:
71 *__buf++ = ' ';
72 break;
73 }
74
75 return __buf;
76}
77
78/**
79 * Determines the required grouping based on the size of the input.
80 *
81 * The grouping's last element will be repeated. For simplicity this repeating
82 * is unwrapped based on the length of the input. (When the input is short some
83 * groups are not processed.)
84 *
85 * @returns The size of the groups to write. This means the number of
86 * separator characters written is size() - 1.
87 *
88 * @note Since zero-sized groups cause issues they are silently ignored.
89 *
90 * @note The grouping field of the locale is always a @c std::string,
91 * regardless whether the @c std::numpunct's type is @c char or @c wchar_t.
92 */
93_LIBCPP_HIDE_FROM_ABI inline string __determine_grouping(ptrdiff_t __size, const string& __grouping) {
94 _LIBCPP_ASSERT_INTERNAL(!__grouping.empty() && __size > __grouping[0],
95 "The slow grouping formatting is used while there will be no separators written");
96 string __r;
97 auto __end = __grouping.end() - 1;
98 auto __ptr = __grouping.begin();
99
100 while (true) {
101 __size -= *__ptr;
102 if (__size > 0)
103 __r.push_back(*__ptr);
104 else {
105 // __size <= 0 so the value pushed will be <= *__ptr.
106 __r.push_back(*__ptr + __size);
107 return __r;
108 }
109
110 // Proceed to the next group.
111 if (__ptr != __end) {
112 do {
113 ++__ptr;
114 // Skip grouping with a width of 0.
115 } while (*__ptr == 0 && __ptr != __end);
116 }
117 }
118
119 __libcpp_unreachable();
120}
121
122//
123// Char
124//
125
126template <__fmt_char_type _CharT>
127_LIBCPP_HIDE_FROM_ABI auto
128__format_char(integral auto __value,
129 output_iterator<const _CharT&> auto __out_it,
130 __format_spec::__parsed_specifications<_CharT> __specs) -> decltype(__out_it) {
131 using _Tp = decltype(__value);
132 if constexpr (!same_as<_CharT, _Tp>) {
133 // cmp_less and cmp_greater can't be used for character types.
134 if constexpr (signed_integral<_CharT> == signed_integral<_Tp>) {
135 if (__value < numeric_limits<_CharT>::min() || __value > numeric_limits<_CharT>::max())
136 std::__throw_format_error("Integral value outside the range of the char type");
137 } else if constexpr (signed_integral<_CharT>) {
138 // _CharT is signed _Tp is unsigned
139 if (__value > static_cast<make_unsigned_t<_CharT>>(numeric_limits<_CharT>::max()))
140 std::__throw_format_error("Integral value outside the range of the char type");
141 } else {
142 // _CharT is unsigned _Tp is signed
143 if (__value < 0 || static_cast<make_unsigned_t<_Tp>>(__value) > numeric_limits<_CharT>::max())
144 std::__throw_format_error("Integral value outside the range of the char type");
145 }
146 }
147
148 const auto __c = static_cast<_CharT>(__value);
149 return __formatter::__write(std::addressof(__c), std::addressof(__c) + 1, std::move(__out_it), __specs);
150}
151
152//
153// Integer
154//
155
156/** Wrapper around @ref to_chars, returning the output iterator. */
157template <contiguous_iterator _Iterator, integral _Tp>
158 requires same_as<char, iter_value_t<_Iterator>>
159_LIBCPP_HIDE_FROM_ABI _Iterator __to_buffer(_Iterator __first, _Iterator __last, _Tp __value, int __base) {
160 // TODO FMT Evaluate code overhead due to not calling the internal function
161 // directly. (Should be zero overhead.)
162 to_chars_result __r = std::to_chars(std::to_address(__first), std::to_address(__last), __value, __base);
163 _LIBCPP_ASSERT_INTERNAL(__r.ec == errc(0), "Internal buffer too small");
164 auto __diff = __r.ptr - std::to_address(__first);
165 return __first + __diff;
166}
167
168/**
169 * Helper to determine the buffer size to output a integer in Base @em x.
170 *
171 * There are several overloads for the supported bases. The function uses the
172 * base as template argument so it can be used in a constant expression.
173 */
174template <unsigned_integral _Tp, size_t _Base>
175consteval size_t __buffer_size() noexcept
176 requires(_Base == 2)
177{
178 return numeric_limits<_Tp>::digits // The number of binary digits.
179 + 2 // Reserve space for the '0[Bb]' prefix.
180 + 1; // Reserve space for the sign.
181}
182
183template <unsigned_integral _Tp, size_t _Base>
184consteval size_t __buffer_size() noexcept
185 requires(_Base == 8)
186{
187 return numeric_limits<_Tp>::digits // The number of binary digits.
188 / 3 // Adjust to octal.
189 + 1 // Turn floor to ceil.
190 + 1 // Reserve space for the '0' prefix.
191 + 1; // Reserve space for the sign.
192}
193
194template <unsigned_integral _Tp, size_t _Base>
195consteval size_t __buffer_size() noexcept
196 requires(_Base == 10)
197{
198 return numeric_limits<_Tp>::digits10 // The floored value.
199 + 1 // Turn floor to ceil.
200 + 1; // Reserve space for the sign.
201}
202
203template <unsigned_integral _Tp, size_t _Base>
204consteval size_t __buffer_size() noexcept
205 requires(_Base == 16)
206{
207 return numeric_limits<_Tp>::digits // The number of binary digits.
208 / 4 // Adjust to hexadecimal.
209 + 2 // Reserve space for the '0[Xx]' prefix.
210 + 1; // Reserve space for the sign.
211}
212
213template <class _OutIt, contiguous_iterator _Iterator, class _CharT>
214 requires same_as<char, iter_value_t<_Iterator>>
215_LIBCPP_HIDE_FROM_ABI _OutIt __write_using_decimal_separators(
216 _OutIt __out_it,
217 _Iterator __begin,
218 _Iterator __first,
219 _Iterator __last,
220 string&& __grouping,
221 _CharT __sep,
222 __format_spec::__parsed_specifications<_CharT> __specs) {
223 int __size = (__first - __begin) + // [sign][prefix]
224 (__last - __first) + // data
225 (__grouping.size() - 1); // number of separator characters
226
227 __padding_size_result __padding = {0, 0};
228 if (__specs.__alignment_ == __format_spec::__alignment::__zero_padding) {
229 // Write [sign][prefix].
230 __out_it = __formatter::__copy(__begin, __first, std::move(__out_it));
231
232 if (__specs.__width_ > __size) {
233 // Write zero padding.
234 __padding.__before_ = __specs.__width_ - __size;
235 __out_it = __formatter::__fill(std::move(__out_it), __specs.__width_ - __size, _CharT('0'));
236 }
237 } else {
238 if (__specs.__width_ > __size) {
239 // Determine padding and write padding.
240 __padding = __formatter::__padding_size(__size, __specs.__width_, __specs.__alignment_);
241
242 __out_it = __formatter::__fill(std::move(__out_it), __padding.__before_, __specs.__fill_);
243 }
244 // Write [sign][prefix].
245 __out_it = __formatter::__copy(__begin, __first, std::move(__out_it));
246 }
247
248 auto __r = __grouping.rbegin();
249 auto __e = __grouping.rend() - 1;
250 _LIBCPP_ASSERT_INTERNAL(
251 __r != __e, "The slow grouping formatting is used while there will be no separators written.");
252 // The output is divided in small groups of numbers to write:
253 // - A group before the first separator.
254 // - A separator and a group, repeated for the number of separators.
255 // - A group after the last separator.
256 // This loop achieves that process by testing the termination condition
257 // midway in the loop.
258 //
259 // TODO FMT This loop evaluates the loop invariant `__parser.__type !=
260 // _Flags::_Type::__hexadecimal_upper_case` for every iteration. (This test
261 // happens in the __write call.) Benchmark whether making two loops and
262 // hoisting the invariant is worth the effort.
263 while (true) {
264 if (__specs.__std_.__type_ == __format_spec::__type::__hexadecimal_upper_case) {
265 __last = __first + *__r;
266 __out_it = __formatter::__transform(__first, __last, std::move(__out_it), __hex_to_upper);
267 __first = __last;
268 } else {
269 __out_it = __formatter::__copy(__first, *__r, std::move(__out_it));
270 __first += *__r;
271 }
272
273 if (__r == __e)
274 break;
275
276 ++__r;
277 *__out_it++ = __sep;
278 }
279
280 return __formatter::__fill(std::move(__out_it), __padding.__after_, __specs.__fill_);
281}
282
283template <unsigned_integral _Tp, contiguous_iterator _Iterator, class _CharT, class _FormatContext>
284 requires same_as<char, iter_value_t<_Iterator>>
285_LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator __format_integer(
286 _Tp __value,
287 _FormatContext& __ctx,
288 __format_spec::__parsed_specifications<_CharT> __specs,
289 bool __negative,
290 _Iterator __begin,
291 _Iterator __end,
292 const char* __prefix,
293 int __base) {
294 _Iterator __first = __formatter::__insert_sign(__begin, __negative, __specs.__std_.__sign_);
295 if (__specs.__std_.__alternate_form_ && __prefix)
296 while (*__prefix)
297 *__first++ = *__prefix++;
298
299 _Iterator __last = __formatter::__to_buffer(__first, __end, __value, __base);
300
301# if _LIBCPP_HAS_LOCALIZATION
302 if (__specs.__std_.__locale_specific_form_) {
303 const auto& __np = std::use_facet<numpunct<_CharT>>(__ctx.locale());
304 string __grouping = __np.grouping();
305 ptrdiff_t __size = __last - __first;
306 // Writing the grouped form has more overhead than the normal output
307 // routines. If there will be no separators written the locale-specific
308 // form is identical to the normal routine. Test whether to grouped form
309 // is required.
310 if (!__grouping.empty() && __size > __grouping[0])
311 return __formatter::__write_using_decimal_separators(
312 __ctx.out(),
313 __begin,
314 __first,
315 __last,
316 __formatter::__determine_grouping(__size, __grouping),
317 __np.thousands_sep(),
318 __specs);
319 }
320# endif
321 auto __out_it = __ctx.out();
322 if (__specs.__alignment_ != __format_spec::__alignment::__zero_padding)
323 __first = __begin;
324 else {
325 // __buf contains [sign][prefix]data
326 // ^ location of __first
327 // The zero padding is done like:
328 // - Write [sign][prefix]
329 // - Write data right aligned with '0' as fill character.
330 __out_it = __formatter::__copy(__begin, __first, std::move(__out_it));
331 __specs.__alignment_ = __format_spec::__alignment::__right;
332 __specs.__fill_.__data[0] = _CharT('0');
333 int32_t __size = __first - __begin;
334
335 __specs.__width_ -= std::min(__size, __specs.__width_);
336 }
337
338 if (__specs.__std_.__type_ != __format_spec::__type::__hexadecimal_upper_case) [[likely]]
339 return __formatter::__write(__first, __last, __ctx.out(), __specs);
340
341 return __formatter::__write_transformed(__first, __last, __ctx.out(), __specs, std::__hex_to_upper);
342}
343
344template <unsigned_integral _Tp, class _CharT, class _FormatContext>
345_LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator
346__format_integer(_Tp __value,
347 _FormatContext& __ctx,
348 __format_spec::__parsed_specifications<_CharT> __specs,
349 bool __negative = false) {
350 switch (__specs.__std_.__type_) {
351 case __format_spec::__type::__binary_lower_case: {
352 array<char, __formatter::__buffer_size<decltype(__value), 2>()> __array;
353 return __formatter::__format_integer(__value, __ctx, __specs, __negative, __array.begin(), __array.end(), "0b", 2);
354 }
355 case __format_spec::__type::__binary_upper_case: {
356 array<char, __formatter::__buffer_size<decltype(__value), 2>()> __array;
357 return __formatter::__format_integer(__value, __ctx, __specs, __negative, __array.begin(), __array.end(), "0B", 2);
358 }
359 case __format_spec::__type::__octal: {
360 // Octal is special; if __value == 0 there's no prefix.
361 array<char, __formatter::__buffer_size<decltype(__value), 8>()> __array;
362 return __formatter::__format_integer(
363 __value, __ctx, __specs, __negative, __array.begin(), __array.end(), __value != 0 ? "0" : nullptr, 8);
364 }
365 case __format_spec::__type::__default:
366 case __format_spec::__type::__decimal: {
367 array<char, __formatter::__buffer_size<decltype(__value), 10>()> __array;
368 return __formatter::__format_integer(
369 __value, __ctx, __specs, __negative, __array.begin(), __array.end(), nullptr, 10);
370 }
371 case __format_spec::__type::__hexadecimal_lower_case: {
372 array<char, __formatter::__buffer_size<decltype(__value), 16>()> __array;
373 return __formatter::__format_integer(__value, __ctx, __specs, __negative, __array.begin(), __array.end(), "0x", 16);
374 }
375 case __format_spec::__type::__hexadecimal_upper_case: {
376 array<char, __formatter::__buffer_size<decltype(__value), 16>()> __array;
377 return __formatter::__format_integer(__value, __ctx, __specs, __negative, __array.begin(), __array.end(), "0X", 16);
378 }
379 default:
380 _LIBCPP_ASSERT_INTERNAL(false, "The parse function should have validated the type");
381 __libcpp_unreachable();
382 }
383}
384
385template <signed_integral _Tp, class _CharT, class _FormatContext>
386_LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator
387__format_integer(_Tp __value, _FormatContext& __ctx, __format_spec::__parsed_specifications<_CharT> __specs) {
388 // Depending on the std-format-spec string the sign and the value
389 // might not be outputted together:
390 // - alternate form may insert a prefix string.
391 // - zero-padding may insert additional '0' characters.
392 // Therefore the value is processed as a positive unsigned value.
393 // The function @ref __insert_sign will a '-' when the value was negative.
394 auto __r = std::__to_unsigned_like(__value);
395 bool __negative = __value < 0;
396 if (__negative)
397 __r = std::__complement(__r);
398
399 return __formatter::__format_integer(__r, __ctx, __specs, __negative);
400}
401
402//
403// Formatter arithmetic (bool)
404//
405
406template <class _CharT>
407struct __bool_strings;
408
409template <>
410struct __bool_strings<char> {
411 static constexpr string_view __true{"true"};
412 static constexpr string_view __false{"false"};
413};
414
415# if _LIBCPP_HAS_WIDE_CHARACTERS
416template <>
417struct __bool_strings<wchar_t> {
418 static constexpr wstring_view __true{L"true"};
419 static constexpr wstring_view __false{L"false"};
420};
421# endif
422
423template <class _CharT, class _FormatContext>
424_LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator
425__format_bool(bool __value, _FormatContext& __ctx, __format_spec::__parsed_specifications<_CharT> __specs) {
426# if _LIBCPP_HAS_LOCALIZATION
427 if (__specs.__std_.__locale_specific_form_) {
428 const auto& __np = std::use_facet<numpunct<_CharT>>(__ctx.locale());
429 basic_string<_CharT> __str = __value ? __np.truename() : __np.falsename();
430 return __formatter::__write_string_no_precision(basic_string_view<_CharT>{__str}, __ctx.out(), __specs);
431 }
432# endif
433 basic_string_view<_CharT> __str =
434 __value ? __formatter::__bool_strings<_CharT>::__true : __formatter::__bool_strings<_CharT>::__false;
435 return __formatter::__write(__str.begin(), __str.end(), __ctx.out(), __specs);
436}
437
438} // namespace __formatter
439
440#endif // _LIBCPP_STD_VER >= 20
441
442_LIBCPP_END_NAMESPACE_STD
443
444_LIBCPP_POP_MACROS
445
446#endif // _LIBCPP___FORMAT_FORMATTER_INTEGRAL_H
447

Warning: This file is not a C or C++ file. It does not have highlighting.

source code of libcxx/include/__format/formatter_integral.h