libstdc++
experimental/string_view
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1// Components for manipulating non-owning sequences of characters -*- C++ -*-
2
3// Copyright (C) 2013-2023 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
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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 experimental/string_view
26 * This is a TS C++ Library header.
27 * @ingroup libfund-ts
28 */
29
30//
31// N3762 basic_string_view library
32//
33
34#ifndef _GLIBCXX_EXPERIMENTAL_STRING_VIEW
35#define _GLIBCXX_EXPERIMENTAL_STRING_VIEW 1
36
37#pragma GCC system_header
38
39#include <bits/requires_hosted.h> // experimental is currently omitted
40
41#if __cplusplus >= 201402L
42
43#include <string>
44#include <limits>
45#include <bits/ranges_base.h> // enable_borrowed_range, enable_view
46#include <experimental/bits/lfts_config.h>
47
48namespace std _GLIBCXX_VISIBILITY(default)
49{
50_GLIBCXX_BEGIN_NAMESPACE_VERSION
51
52namespace experimental
53{
54inline namespace fundamentals_v1
55{
56#define __cpp_lib_experimental_string_view 201411
57
58 /**
59 * @class basic_string_view <experimental/string_view>
60 * @brief A non-owning reference to a string.
61 *
62 * @ingroup strings
63 * @ingroup sequences
64 * @ingroup libfund-ts
65 *
66 * @tparam _CharT Type of character
67 * @tparam _Traits Traits for character type, defaults to
68 * char_traits<_CharT>.
69 *
70 * A basic_string_view looks like this:
71 *
72 * @code
73 * _CharT* _M_str
74 * size_t _M_len
75 * @endcode
76 */
77 template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
78 class basic_string_view
79 {
80 public:
81
82 // types
83 using traits_type = _Traits;
84 using value_type = _CharT;
85 using pointer = _CharT*;
86 using const_pointer = const _CharT*;
87 using reference = _CharT&;
88 using const_reference = const _CharT&;
89 using const_iterator = const _CharT*;
90 using iterator = const_iterator;
91 using const_reverse_iterator = std::reverse_iterator<const_iterator>;
92 using reverse_iterator = const_reverse_iterator;
93 using size_type = size_t;
94 using difference_type = ptrdiff_t;
95 static constexpr size_type npos = size_type(-1);
96
97 // [string.view.cons], construct/copy
98
99 constexpr
100 basic_string_view() noexcept
101 : _M_len{0}, _M_str{nullptr}
102 { }
103
104 constexpr basic_string_view(const basic_string_view&) noexcept = default;
105
106 template<typename _Allocator>
107 basic_string_view(const basic_string<_CharT, _Traits,
108 _Allocator>& __str) noexcept
109 : _M_len{__str.length()}, _M_str{__str.data()}
110 { }
111
112 constexpr basic_string_view(const _CharT* __str)
113 : _M_len{__str == nullptr ? 0 : traits_type::length(__str)},
114 _M_str{__str}
115 { }
116
117 constexpr basic_string_view(const _CharT* __str, size_type __len)
118 : _M_len{__len},
119 _M_str{__str}
120 { }
121
122 basic_string_view&
123 operator=(const basic_string_view&) noexcept = default;
124
125 // [string.view.iterators], iterators
126
127 constexpr const_iterator
128 begin() const noexcept
129 { return this->_M_str; }
130
131 constexpr const_iterator
132 end() const noexcept
133 { return this->_M_str + this->_M_len; }
134
135 constexpr const_iterator
136 cbegin() const noexcept
137 { return this->_M_str; }
138
139 constexpr const_iterator
140 cend() const noexcept
141 { return this->_M_str + this->_M_len; }
142
143 const_reverse_iterator
144 rbegin() const noexcept
145 { return const_reverse_iterator(this->end()); }
146
147 const_reverse_iterator
148 rend() const noexcept
149 { return const_reverse_iterator(this->begin()); }
150
151 const_reverse_iterator
152 crbegin() const noexcept
153 { return const_reverse_iterator(this->end()); }
154
155 const_reverse_iterator
156 crend() const noexcept
157 { return const_reverse_iterator(this->begin()); }
158
159 // [string.view.capacity], capacity
160
161 constexpr size_type
162 size() const noexcept
163 { return this->_M_len; }
164
165 constexpr size_type
166 length() const noexcept
167 { return _M_len; }
168
169 constexpr size_type
170 max_size() const noexcept
171 {
172 return (npos - sizeof(size_type) - sizeof(void*))
173 / sizeof(value_type) / 4;
174 }
175
176 _GLIBCXX_NODISCARD constexpr bool
177 empty() const noexcept
178 { return this->_M_len == 0; }
179
180 // [string.view.access], element access
181
182 constexpr const _CharT&
183 operator[](size_type __pos) const
184 {
185 __glibcxx_assert(__pos < this->_M_len);
186 return *(this->_M_str + __pos);
187 }
188
189 constexpr const _CharT&
190 at(size_type __pos) const
191 {
192 return __pos < this->_M_len
193 ? *(this->_M_str + __pos)
194 : (__throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
195 "(which is %zu) >= this->size() "
196 "(which is %zu)"),
197 __pos, this->size()),
198 *this->_M_str);
199 }
200
201 constexpr const _CharT&
202 front() const
203 {
204 __glibcxx_assert(this->_M_len > 0);
205 return *this->_M_str;
206 }
207
208 constexpr const _CharT&
209 back() const
210 {
211 __glibcxx_assert(this->_M_len > 0);
212 return *(this->_M_str + this->_M_len - 1);
213 }
214
215 constexpr const _CharT*
216 data() const noexcept
217 { return this->_M_str; }
218
219 // [string.view.modifiers], modifiers:
220
221 constexpr void
222 remove_prefix(size_type __n)
223 {
224 __glibcxx_assert(this->_M_len >= __n);
225 this->_M_str += __n;
226 this->_M_len -= __n;
227 }
228
229 constexpr void
230 remove_suffix(size_type __n)
231 { this->_M_len -= __n; }
232
233 constexpr void
234 swap(basic_string_view& __sv) noexcept
235 {
236 auto __tmp = *this;
237 *this = __sv;
238 __sv = __tmp;
239 }
240
241
242 // [string.view.ops], string operations:
243
244 template<typename _Allocator>
245 explicit operator basic_string<_CharT, _Traits, _Allocator>() const
246 {
247 return { this->_M_str, this->_M_len };
248 }
249
250 template<typename _Allocator = std::allocator<_CharT>>
251 basic_string<_CharT, _Traits, _Allocator>
252 to_string(const _Allocator& __alloc = _Allocator()) const
253 {
254 return { this->_M_str, this->_M_len, __alloc };
255 }
256
257 size_type
258 copy(_CharT* __str, size_type __n, size_type __pos = 0) const
259 {
260 __glibcxx_requires_string_len(__str, __n);
261 if (__pos > this->_M_len)
262 __throw_out_of_range_fmt(__N("basic_string_view::copy: __pos "
263 "(which is %zu) > this->size() "
264 "(which is %zu)"),
265 __pos, this->size());
266 size_type __rlen{std::min(__n, size_type{this->_M_len - __pos})};
267 for (auto __begin = this->_M_str + __pos,
268 __end = __begin + __rlen; __begin != __end;)
269 *__str++ = *__begin++;
270 return __rlen;
271 }
272
273
274 // [string.view.ops], string operations:
275
276 constexpr basic_string_view
277 substr(size_type __pos = 0, size_type __n = npos) const
278 {
279 return __pos <= this->_M_len
280 ? basic_string_view{this->_M_str + __pos,
281 std::min(__n, size_type{this->_M_len - __pos})}
282 : (__throw_out_of_range_fmt(__N("basic_string_view::substr: __pos "
283 "(which is %zu) > this->size() "
284 "(which is %zu)"),
285 __pos, this->size()), basic_string_view{});
286 }
287
288 constexpr int
289 compare(basic_string_view __str) const noexcept
290 {
291 int __ret = traits_type::compare(this->_M_str, __str._M_str,
292 std::min(this->_M_len, __str._M_len));
293 if (__ret == 0)
294 __ret = _S_compare(this->_M_len, __str._M_len);
295 return __ret;
296 }
297
298 constexpr int
299 compare(size_type __pos1, size_type __n1, basic_string_view __str) const
300 { return this->substr(__pos1, __n1).compare(__str); }
301
302 constexpr int
303 compare(size_type __pos1, size_type __n1,
304 basic_string_view __str, size_type __pos2, size_type __n2) const
305 { return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2)); }
306
307 constexpr int
308 compare(const _CharT* __str) const noexcept
309 { return this->compare(basic_string_view{__str}); }
310
311 constexpr int
312 compare(size_type __pos1, size_type __n1, const _CharT* __str) const
313 { return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
314
315 constexpr int
316 compare(size_type __pos1, size_type __n1,
317 const _CharT* __str, size_type __n2) const
318 {
319 return this->substr(__pos1, __n1)
320 .compare(basic_string_view(__str, __n2));
321 }
322
323 constexpr size_type
324 find(basic_string_view __str, size_type __pos = 0) const noexcept
325 { return this->find(__str._M_str, __pos, __str._M_len); }
326
327 constexpr size_type
328 find(_CharT __c, size_type __pos=0) const noexcept;
329
330 constexpr size_type
331 find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
332
333 constexpr size_type
334 find(const _CharT* __str, size_type __pos=0) const noexcept
335 { return this->find(__str, __pos, traits_type::length(__str)); }
336
337 constexpr size_type
338 rfind(basic_string_view __str, size_type __pos = npos) const noexcept
339 { return this->rfind(__str._M_str, __pos, __str._M_len); }
340
341 constexpr size_type
342 rfind(_CharT __c, size_type __pos = npos) const noexcept;
343
344 constexpr size_type
345 rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
346
347 constexpr size_type
348 rfind(const _CharT* __str, size_type __pos = npos) const noexcept
349 { return this->rfind(__str, __pos, traits_type::length(__str)); }
350
351 constexpr size_type
352 find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
353 { return this->find_first_of(__str._M_str, __pos, __str._M_len); }
354
355 constexpr size_type
356 find_first_of(_CharT __c, size_type __pos = 0) const noexcept
357 { return this->find(__c, __pos); }
358
359 constexpr size_type
360 find_first_of(const _CharT* __str, size_type __pos, size_type __n) const;
361
362 constexpr size_type
363 find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
364 { return this->find_first_of(__str, __pos, traits_type::length(__str)); }
365
366 constexpr size_type
367 find_last_of(basic_string_view __str,
368 size_type __pos = npos) const noexcept
369 { return this->find_last_of(__str._M_str, __pos, __str._M_len); }
370
371 constexpr size_type
372 find_last_of(_CharT __c, size_type __pos=npos) const noexcept
373 { return this->rfind(__c, __pos); }
374
375 constexpr size_type
376 find_last_of(const _CharT* __str, size_type __pos, size_type __n) const;
377
378 constexpr size_type
379 find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
380 { return this->find_last_of(__str, __pos, traits_type::length(__str)); }
381
382 constexpr size_type
383 find_first_not_of(basic_string_view __str,
384 size_type __pos = 0) const noexcept
385 { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
386
387 constexpr size_type
388 find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
389
390 constexpr size_type
391 find_first_not_of(const _CharT* __str,
392 size_type __pos, size_type __n) const;
393
394 constexpr size_type
395 find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
396 {
397 return this->find_first_not_of(__str, __pos,
398 traits_type::length(__str));
399 }
400
401 constexpr size_type
402 find_last_not_of(basic_string_view __str,
403 size_type __pos = npos) const noexcept
404 { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
405
406 constexpr size_type
407 find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
408
409 constexpr size_type
410 find_last_not_of(const _CharT* __str,
411 size_type __pos, size_type __n) const;
412
413 constexpr size_type
414 find_last_not_of(const _CharT* __str,
415 size_type __pos = npos) const noexcept
416 {
417 return this->find_last_not_of(__str, __pos,
418 traits_type::length(__str));
419 }
420
421 private:
422
423 static constexpr int
424 _S_compare(size_type __n1, size_type __n2) noexcept
425 {
426 return difference_type(__n1 - __n2) > std::numeric_limits<int>::max()
427 ? std::numeric_limits<int>::max()
428 : difference_type(__n1 - __n2) < std::numeric_limits<int>::min()
429 ? std::numeric_limits<int>::min()
430 : static_cast<int>(difference_type(__n1 - __n2));
431 }
432
433 size_t _M_len;
434 const _CharT* _M_str;
435 };
436
437 // [string.view.comparison], non-member basic_string_view comparison functions
438
439 // Several of these functions use type_identity_t to create a non-deduced
440 // context, so that only one argument participates in template argument
441 // deduction and the other argument gets implicitly converted to the deduced
442 // type (see N3766).
443
444 template<typename _CharT, typename _Traits>
445 constexpr bool
446 operator==(basic_string_view<_CharT, _Traits> __x,
447 basic_string_view<_CharT, _Traits> __y) noexcept
448 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
449
450 template<typename _CharT, typename _Traits>
451 constexpr bool
452 operator==(basic_string_view<_CharT, _Traits> __x,
453 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
454 noexcept
455 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
456
457 template<typename _CharT, typename _Traits>
458 constexpr bool
459 operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
460 basic_string_view<_CharT, _Traits> __y) noexcept
461 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
462
463 template<typename _CharT, typename _Traits>
464 constexpr bool
465 operator!=(basic_string_view<_CharT, _Traits> __x,
466 basic_string_view<_CharT, _Traits> __y) noexcept
467 { return !(__x == __y); }
468
469 template<typename _CharT, typename _Traits>
470 constexpr bool
471 operator!=(basic_string_view<_CharT, _Traits> __x,
472 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
473 noexcept
474 { return !(__x == __y); }
475
476 template<typename _CharT, typename _Traits>
477 constexpr bool
478 operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
479 basic_string_view<_CharT, _Traits> __y) noexcept
480 { return !(__x == __y); }
481
482 template<typename _CharT, typename _Traits>
483 constexpr bool
484 operator< (basic_string_view<_CharT, _Traits> __x,
485 basic_string_view<_CharT, _Traits> __y) noexcept
486 { return __x.compare(__y) < 0; }
487
488 template<typename _CharT, typename _Traits>
489 constexpr bool
490 operator< (basic_string_view<_CharT, _Traits> __x,
491 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
492 noexcept
493 { return __x.compare(__y) < 0; }
494
495 template<typename _CharT, typename _Traits>
496 constexpr bool
497 operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
498 basic_string_view<_CharT, _Traits> __y) noexcept
499 { return __x.compare(__y) < 0; }
500
501 template<typename _CharT, typename _Traits>
502 constexpr bool
503 operator> (basic_string_view<_CharT, _Traits> __x,
504 basic_string_view<_CharT, _Traits> __y) noexcept
505 { return __x.compare(__y) > 0; }
506
507 template<typename _CharT, typename _Traits>
508 constexpr bool
509 operator> (basic_string_view<_CharT, _Traits> __x,
510 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
511 noexcept
512 { return __x.compare(__y) > 0; }
513
514 template<typename _CharT, typename _Traits>
515 constexpr bool
516 operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
517 basic_string_view<_CharT, _Traits> __y) noexcept
518 { return __x.compare(__y) > 0; }
519
520 template<typename _CharT, typename _Traits>
521 constexpr bool
522 operator<=(basic_string_view<_CharT, _Traits> __x,
523 basic_string_view<_CharT, _Traits> __y) noexcept
524 { return __x.compare(__y) <= 0; }
525
526 template<typename _CharT, typename _Traits>
527 constexpr bool
528 operator<=(basic_string_view<_CharT, _Traits> __x,
529 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
530 noexcept
531 { return __x.compare(__y) <= 0; }
532
533 template<typename _CharT, typename _Traits>
534 constexpr bool
535 operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
536 basic_string_view<_CharT, _Traits> __y) noexcept
537 { return __x.compare(__y) <= 0; }
538
539 template<typename _CharT, typename _Traits>
540 constexpr bool
541 operator>=(basic_string_view<_CharT, _Traits> __x,
542 basic_string_view<_CharT, _Traits> __y) noexcept
543 { return __x.compare(__y) >= 0; }
544
545 template<typename _CharT, typename _Traits>
546 constexpr bool
547 operator>=(basic_string_view<_CharT, _Traits> __x,
548 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
549 noexcept
550 { return __x.compare(__y) >= 0; }
551
552 template<typename _CharT, typename _Traits>
553 constexpr bool
554 operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
555 basic_string_view<_CharT, _Traits> __y) noexcept
556 { return __x.compare(__y) >= 0; }
557
558 // [string.view.io], Inserters and extractors
559 template<typename _CharT, typename _Traits>
560 inline basic_ostream<_CharT, _Traits>&
561 operator<<(basic_ostream<_CharT, _Traits>& __os,
562 basic_string_view<_CharT,_Traits> __str)
563 { return __ostream_insert(__os, __str.data(), __str.size()); }
564
565
566 // basic_string_view typedef names
567
568 using string_view = basic_string_view<char>;
569 using wstring_view = basic_string_view<wchar_t>;
570#ifdef _GLIBCXX_USE_CHAR8_T
571 using u8string_view = basic_string_view<char8_t>;
572#endif
573 using u16string_view = basic_string_view<char16_t>;
574 using u32string_view = basic_string_view<char32_t>;
575} // namespace fundamentals_v1
576} // namespace experimental
577
578
579 // [string.view.hash], hash support:
580 template<typename _Tp>
581 struct hash;
582
583 template<>
584 struct hash<experimental::string_view>
585 : public __hash_base<size_t, experimental::string_view>
586 {
587 size_t
588 operator()(const experimental::string_view& __str) const noexcept
589 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
590 };
591
592 template<>
593 struct __is_fast_hash<hash<experimental::string_view>> : std::false_type
594 { };
595
596 template<>
597 struct hash<experimental::wstring_view>
598 : public __hash_base<size_t, wstring>
599 {
600 size_t
601 operator()(const experimental::wstring_view& __s) const noexcept
602 { return std::_Hash_impl::hash(__s.data(),
603 __s.length() * sizeof(wchar_t)); }
604 };
605
606 template<>
607 struct __is_fast_hash<hash<experimental::wstring_view>> : std::false_type
608 { };
609
610#ifdef _GLIBCXX_USE_CHAR8_T
611 template<>
612 struct hash<experimental::u8string_view>
613 : public __hash_base<size_t, experimental::u8string_view>
614 {
615 size_t
616 operator()(const experimental::u8string_view& __s) const noexcept
617 { return std::_Hash_impl::hash(__s.data(), __s.length()); }
618 };
619
620 template<>
621 struct __is_fast_hash<hash<experimental::u8string_view>> : std::false_type
622 { };
623#endif
624
625 template<>
626 struct hash<experimental::u16string_view>
627 : public __hash_base<size_t, experimental::u16string_view>
628 {
629 size_t
630 operator()(const experimental::u16string_view& __s) const noexcept
631 { return std::_Hash_impl::hash(__s.data(),
632 __s.length() * sizeof(char16_t)); }
633 };
634
635 template<>
636 struct __is_fast_hash<hash<experimental::u16string_view>> : std::false_type
637 { };
638
639 template<>
640 struct hash<experimental::u32string_view>
641 : public __hash_base<size_t, experimental::u32string_view>
642 {
643 size_t
644 operator()(const experimental::u32string_view& __s) const noexcept
645 { return std::_Hash_impl::hash(__s.data(),
646 __s.length() * sizeof(char32_t)); }
647 };
648
649 template<>
650 struct __is_fast_hash<hash<experimental::u32string_view>> : std::false_type
651 { };
652
653namespace experimental
654{
655 // I added these EMSR.
656 inline namespace literals
657 {
658 inline namespace string_view_literals
659 {
660#pragma GCC diagnostic push
661#pragma GCC diagnostic ignored "-Wliteral-suffix"
662 inline constexpr basic_string_view<char>
663 operator""sv(const char* __str, size_t __len) noexcept
664 { return basic_string_view<char>{__str, __len}; }
665
666 inline constexpr basic_string_view<wchar_t>
667 operator""sv(const wchar_t* __str, size_t __len) noexcept
668 { return basic_string_view<wchar_t>{__str, __len}; }
669
670#ifdef _GLIBCXX_USE_CHAR8_T
671 inline constexpr basic_string_view<char8_t>
672 operator""sv(const char8_t* __str, size_t __len) noexcept
673 { return basic_string_view<char8_t>{__str, __len}; }
674#endif
675
676 inline constexpr basic_string_view<char16_t>
677 operator""sv(const char16_t* __str, size_t __len) noexcept
678 { return basic_string_view<char16_t>{__str, __len}; }
679
680 inline constexpr basic_string_view<char32_t>
681 operator""sv(const char32_t* __str, size_t __len) noexcept
682 { return basic_string_view<char32_t>{__str, __len}; }
683#pragma GCC diagnostic pop
684 } // namespace string_literals
685 } // namespace literals
686} // namespace experimental
687
688#if __cpp_lib_concepts
689 namespace ranges
690 {
691 // Opt-in to borrowed_range concept
692 template<typename _CharT, typename _Traits>
693 inline constexpr bool
694 enable_borrowed_range<experimental::basic_string_view<_CharT, _Traits>>
695 = true;
696
697 // Opt-in to view concept
698 template<typename _CharT, typename _Traits>
699 inline constexpr bool
700 enable_view<experimental::basic_string_view<_CharT, _Traits>> = true;
701 }
702#endif
703
704_GLIBCXX_END_NAMESPACE_VERSION
705} // namespace std
706
707#include <experimental/bits/string_view.tcc>
708
709#endif // __cplusplus <= 201103L
710
711#endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW