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_OUTPUT_H
11 #define _LIBCPP___FORMAT_FORMATTER_OUTPUT_H
12
13 #include <__algorithm/ranges_copy.h>
14 #include <__algorithm/ranges_fill_n.h>
15 #include <__algorithm/ranges_transform.h>
16 #include <__bit/countl.h>
17 #include <__concepts/same_as.h>
18 #include <__config>
19 #include <__format/buffer.h>
20 #include <__format/concepts.h>
21 #include <__format/formatter.h>
22 #include <__format/parser_std_format_spec.h>
23 #include <__format/unicode.h>
24 #include <__iterator/back_insert_iterator.h>
25 #include <__iterator/concepts.h>
26 #include <__iterator/iterator_traits.h>
27 #include <__memory/addressof.h>
28 #include <__memory/pointer_traits.h>
29 #include <__utility/move.h>
30 #include <__utility/unreachable.h>
31 #include <cstddef>
32 #include <string_view>
33
34 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
35 # pragma GCC system_header
36 #endif
37
38 _LIBCPP_PUSH_MACROS
39 #include <__undef_macros>
40
41 _LIBCPP_BEGIN_NAMESPACE_STD
42
43 #if _LIBCPP_STD_VER >= 20
44
45 namespace __formatter {
46
__hex_to_upper(char __c)47 _LIBCPP_HIDE_FROM_ABI constexpr char __hex_to_upper(char __c) {
48 switch (__c) {
49 case 'a':
50 return 'A';
51 case 'b':
52 return 'B';
53 case 'c':
54 return 'C';
55 case 'd':
56 return 'D';
57 case 'e':
58 return 'E';
59 case 'f':
60 return 'F';
61 }
62 return __c;
63 }
64
65 struct _LIBCPP_EXPORTED_FROM_ABI __padding_size_result {
66 size_t __before_;
67 size_t __after_;
68 };
69
70 _LIBCPP_HIDE_FROM_ABI constexpr __padding_size_result
__padding_size(size_t __size,size_t __width,__format_spec::__alignment __align)71 __padding_size(size_t __size, size_t __width, __format_spec::__alignment __align) {
72 _LIBCPP_ASSERT_INTERNAL(__width > __size, "don't call this function when no padding is required");
73 _LIBCPP_ASSERT_INTERNAL(
74 __align != __format_spec::__alignment::__zero_padding, "the caller should have handled the zero-padding");
75
76 size_t __fill = __width - __size;
77 switch (__align) {
78 case __format_spec::__alignment::__zero_padding:
79 __libcpp_unreachable();
80
81 case __format_spec::__alignment::__left:
82 return {0, __fill};
83
84 case __format_spec::__alignment::__center: {
85 // The extra padding is divided per [format.string.std]/3
86 // __before = floor(__fill, 2);
87 // __after = ceil(__fill, 2);
88 size_t __before = __fill / 2;
89 size_t __after = __fill - __before;
90 return {__before, __after};
91 }
92 case __format_spec::__alignment::__default:
93 case __format_spec::__alignment::__right:
94 return {__fill, 0};
95 }
96 __libcpp_unreachable();
97 }
98
99 /// Copy wrapper.
100 ///
101 /// This uses a "mass output function" of __format::__output_buffer when possible.
102 template <__fmt_char_type _CharT, __fmt_char_type _OutCharT = _CharT>
103 _LIBCPP_HIDE_FROM_ABI auto
104 __copy(basic_string_view<_CharT> __str, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
105 if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_OutCharT>>>) {
106 __out_it.__get_container()->__copy(__str);
107 return __out_it;
108 } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_OutCharT>::__iterator>) {
109 __out_it.__buffer_->__copy(__str);
110 return __out_it;
111 } else {
112 return std::ranges::copy(__str, std::move(__out_it)).out;
113 }
114 }
115
116 template <contiguous_iterator _Iterator,
117 __fmt_char_type _CharT = typename iterator_traits<_Iterator>::value_type,
118 __fmt_char_type _OutCharT = _CharT>
119 _LIBCPP_HIDE_FROM_ABI auto
120 __copy(_Iterator __first, _Iterator __last, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
121 return __formatter::__copy(basic_string_view{__first, __last}, std::move(__out_it));
122 }
123
124 template <contiguous_iterator _Iterator,
125 __fmt_char_type _CharT = typename iterator_traits<_Iterator>::value_type,
126 __fmt_char_type _OutCharT = _CharT>
127 _LIBCPP_HIDE_FROM_ABI auto
128 __copy(_Iterator __first, size_t __n, output_iterator<const _OutCharT&> auto __out_it) -> decltype(__out_it) {
129 return __formatter::__copy(basic_string_view{std::to_address(__first), __n}, std::move(__out_it));
130 }
131
132 /// Transform wrapper.
133 ///
134 /// This uses a "mass output function" of __format::__output_buffer when possible.
135 template <contiguous_iterator _Iterator,
136 __fmt_char_type _CharT = typename iterator_traits<_Iterator>::value_type,
137 __fmt_char_type _OutCharT = _CharT,
138 class _UnaryOperation>
139 _LIBCPP_HIDE_FROM_ABI auto
140 __transform(_Iterator __first,
141 _Iterator __last,
142 output_iterator<const _OutCharT&> auto __out_it,
143 _UnaryOperation __operation) -> decltype(__out_it) {
144 if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_OutCharT>>>) {
145 __out_it.__get_container()->__transform(__first, __last, std::move(__operation));
146 return __out_it;
147 } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_OutCharT>::__iterator>) {
148 __out_it.__buffer_->__transform(__first, __last, std::move(__operation));
149 return __out_it;
150 } else {
151 return std::ranges::transform(__first, __last, std::move(__out_it), __operation).out;
152 }
153 }
154
155 /// Fill wrapper.
156 ///
157 /// This uses a "mass output function" of __format::__output_buffer when possible.
158 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
__fill(_OutIt __out_it,size_t __n,_CharT __value)159 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, _CharT __value) {
160 if constexpr (std::same_as<decltype(__out_it), std::back_insert_iterator<__format::__output_buffer<_CharT>>>) {
161 __out_it.__get_container()->__fill(__n, __value);
162 return __out_it;
163 } else if constexpr (std::same_as<decltype(__out_it), typename __format::__retarget_buffer<_CharT>::__iterator>) {
164 __out_it.__buffer_->__fill(__n, __value);
165 return __out_it;
166 } else {
167 return std::ranges::fill_n(std::move(__out_it), __n, __value);
168 }
169 }
170
171 # ifndef _LIBCPP_HAS_NO_UNICODE
172 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
requires(same_as<_CharT,char>)173 requires(same_as<_CharT, char>)
174 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
175 std::size_t __bytes = std::countl_one(static_cast<unsigned char>(__value.__data[0]));
176 if (__bytes == 0)
177 return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
178
179 for (size_t __i = 0; __i < __n; ++__i)
180 __out_it = __formatter::__copy(
181 std::addressof(__value.__data[0]), std::addressof(__value.__data[0]) + __bytes, std::move(__out_it));
182 return __out_it;
183 }
184
185 # ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
186 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
187 requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 2)
__fill(_OutIt __out_it,size_t __n,__format_spec::__code_point<_CharT> __value)188 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
189 if (!__unicode::__is_high_surrogate(__value.__data[0]))
190 return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
191
192 for (size_t __i = 0; __i < __n; ++__i)
193 __out_it = __formatter::__copy(
194 std::addressof(__value.__data[0]), std::addressof(__value.__data[0]) + 2, std::move(__out_it));
195 return __out_it;
196 }
197
198 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
199 requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 4)
__fill(_OutIt __out_it,size_t __n,__format_spec::__code_point<_CharT> __value)200 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
201 return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
202 }
203 # endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
204 # else // _LIBCPP_HAS_NO_UNICODE
205 template <__fmt_char_type _CharT, output_iterator<const _CharT&> _OutIt>
__fill(_OutIt __out_it,size_t __n,__format_spec::__code_point<_CharT> __value)206 _LIBCPP_HIDE_FROM_ABI _OutIt __fill(_OutIt __out_it, size_t __n, __format_spec::__code_point<_CharT> __value) {
207 return __formatter::__fill(std::move(__out_it), __n, __value.__data[0]);
208 }
209 # endif // _LIBCPP_HAS_NO_UNICODE
210
211 /// Writes the input to the output with the required padding.
212 ///
213 /// Since the output column width is specified the function can be used for
214 /// ASCII and Unicode output.
215 ///
216 /// \pre \a __size <= \a __width. Using this function when this pre-condition
217 /// doesn't hold incurs an unwanted overhead.
218 ///
219 /// \param __str The string to write.
220 /// \param __out_it The output iterator to write to.
221 /// \param __specs The parsed formatting specifications.
222 /// \param __size The (estimated) output column width. When the elements
223 /// to be written are ASCII the following condition holds
224 /// \a __size == \a __last - \a __first.
225 ///
226 /// \returns An iterator pointing beyond the last element written.
227 ///
228 /// \note The type of the elements in range [\a __first, \a __last) can differ
229 /// from the type of \a __specs. Integer output uses \c std::to_chars for its
230 /// conversion, which means the [\a __first, \a __last) always contains elements
231 /// of the type \c char.
232 template <class _CharT, class _ParserCharT>
233 _LIBCPP_HIDE_FROM_ABI auto
234 __write(basic_string_view<_CharT> __str,
235 output_iterator<const _CharT&> auto __out_it,
236 __format_spec::__parsed_specifications<_ParserCharT> __specs,
237 ptrdiff_t __size) -> decltype(__out_it) {
238 if (__size >= __specs.__width_)
239 return __formatter::__copy(__str, std::move(__out_it));
240
241 __padding_size_result __padding = __formatter::__padding_size(__size, __specs.__width_, __specs.__std_.__alignment_);
242 __out_it = __formatter::__fill(std::move(__out_it), __padding.__before_, __specs.__fill_);
243 __out_it = __formatter::__copy(__str, std::move(__out_it));
244 return __formatter::__fill(std::move(__out_it), __padding.__after_, __specs.__fill_);
245 }
246
247 template <contiguous_iterator _Iterator, class _ParserCharT>
248 _LIBCPP_HIDE_FROM_ABI auto
249 __write(_Iterator __first,
250 _Iterator __last,
251 output_iterator<const iter_value_t<_Iterator>&> auto __out_it,
252 __format_spec::__parsed_specifications<_ParserCharT> __specs,
253 ptrdiff_t __size) -> decltype(__out_it) {
254 _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
255 return __formatter::__write(basic_string_view{__first, __last}, std::move(__out_it), __specs, __size);
256 }
257
258 /// \overload
259 ///
260 /// Calls the function above where \a __size = \a __last - \a __first.
261 template <contiguous_iterator _Iterator, class _ParserCharT>
262 _LIBCPP_HIDE_FROM_ABI auto
263 __write(_Iterator __first,
264 _Iterator __last,
265 output_iterator<const iter_value_t<_Iterator>&> auto __out_it,
266 __format_spec::__parsed_specifications<_ParserCharT> __specs) -> decltype(__out_it) {
267 _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
268 return __formatter::__write(__first, __last, std::move(__out_it), __specs, __last - __first);
269 }
270
271 template <contiguous_iterator _Iterator,
272 class _CharT = typename iterator_traits<_Iterator>::value_type,
273 class _ParserCharT,
274 class _UnaryOperation>
275 _LIBCPP_HIDE_FROM_ABI auto __write_transformed(
276 _Iterator __first,
277 _Iterator __last,
278 output_iterator<const _CharT&> auto __out_it,
279 __format_spec::__parsed_specifications<_ParserCharT> __specs,
280 _UnaryOperation __op) -> decltype(__out_it) {
281 _LIBCPP_ASSERT_VALID_INPUT_RANGE(__first <= __last, "Not a valid range");
282
283 ptrdiff_t __size = __last - __first;
284 if (__size >= __specs.__width_)
285 return __formatter::__transform(__first, __last, std::move(__out_it), __op);
286
287 __padding_size_result __padding = __formatter::__padding_size(__size, __specs.__width_, __specs.__alignment_);
288 __out_it = __formatter::__fill(std::move(__out_it), __padding.__before_, __specs.__fill_);
289 __out_it = __formatter::__transform(__first, __last, std::move(__out_it), __op);
290 return __formatter::__fill(std::move(__out_it), __padding.__after_, __specs.__fill_);
291 }
292
293 /// Writes a string using format's width estimation algorithm.
294 ///
295 /// \pre !__specs.__has_precision()
296 ///
297 /// \note When \c _LIBCPP_HAS_NO_UNICODE is defined the function assumes the
298 /// input is ASCII.
299 template <class _CharT>
300 _LIBCPP_HIDE_FROM_ABI auto __write_string_no_precision(
301 basic_string_view<_CharT> __str,
302 output_iterator<const _CharT&> auto __out_it,
303 __format_spec::__parsed_specifications<_CharT> __specs) -> decltype(__out_it) {
304 _LIBCPP_ASSERT_INTERNAL(!__specs.__has_precision(), "use __write_string");
305
306 // No padding -> copy the string
307 if (!__specs.__has_width())
308 return __formatter::__copy(__str, std::move(__out_it));
309
310 // Note when the estimated width is larger than size there's no padding. So
311 // there's no reason to get the real size when the estimate is larger than or
312 // equal to the minimum field width.
313 size_t __size =
314 __format_spec::__estimate_column_width(__str, __specs.__width_, __format_spec::__column_width_rounding::__up)
315 .__width_;
316 return __formatter::__write(__str, std::move(__out_it), __specs, __size);
317 }
318
319 template <class _CharT>
__truncate(basic_string_view<_CharT> & __str,int __precision)320 _LIBCPP_HIDE_FROM_ABI int __truncate(basic_string_view<_CharT>& __str, int __precision) {
321 __format_spec::__column_width_result __result =
322 __format_spec::__estimate_column_width(__str, __precision, __format_spec::__column_width_rounding::__down);
323 __str = basic_string_view<_CharT>{__str.begin(), __result.__last_};
324 return __result.__width_;
325 }
326
327 } // namespace __formatter
328
329 #endif //_LIBCPP_STD_VER >= 20
330
331 _LIBCPP_END_NAMESPACE_STD
332
333 _LIBCPP_POP_MACROS
334
335 #endif // _LIBCPP___FORMAT_FORMATTER_OUTPUT_H
336