1// Components for manipulating non-owning sequences of characters -*- C++ -*-
2
3// Copyright (C) 2013-2018 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
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/>.
24
25/** @file string_view
26 * This is a Standard C++ Library header.
27 */
28
29//
30// N3762 basic_string_view library
31//
32
33#ifndef _GLIBCXX_STRING_VIEW
34#define _GLIBCXX_STRING_VIEW 1
35
36#pragma GCC system_header
37
38#if __cplusplus >= 201703L
39
40#include <limits>
41#include <iosfwd>
42#include <bits/char_traits.h>
43#include <bits/functional_hash.h>
44#include <bits/range_access.h>
45
46namespace std _GLIBCXX_VISIBILITY(default)
47{
48_GLIBCXX_BEGIN_NAMESPACE_VERSION
49
50#define __cpp_lib_string_view 201603
51
52 /**
53 * @class basic_string_view <string_view>
54 * @brief A non-owning reference to a string.
55 *
56 * @ingroup strings
57 * @ingroup sequences
58 *
59 * @tparam _CharT Type of character
60 * @tparam _Traits Traits for character type, defaults to
61 * char_traits<_CharT>.
62 *
63 * A basic_string_view looks like this:
64 *
65 * @code
66 * _CharT* _M_str
67 * size_t _M_len
68 * @endcode
69 */
70 template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
71 class basic_string_view
72 {
73 public:
74
75 // types
76 using traits_type = _Traits;
77 using value_type = _CharT;
78 using pointer = const _CharT*;
79 using const_pointer = const _CharT*;
80 using reference = const _CharT&;
81 using const_reference = const _CharT&;
82 using const_iterator = const _CharT*;
83 using iterator = const_iterator;
84 using const_reverse_iterator = std::reverse_iterator<const_iterator>;
85 using reverse_iterator = const_reverse_iterator;
86 using size_type = size_t;
87 using difference_type = ptrdiff_t;
88 static constexpr size_type npos = size_type(-1);
89
90 // [string.view.cons], construct/copy
91
92 constexpr
93 basic_string_view() noexcept
94 : _M_len{0}, _M_str{nullptr}
95 { }
96
97 constexpr basic_string_view(const basic_string_view&) noexcept = default;
98
99 constexpr basic_string_view(const _CharT* __str) noexcept
100 : _M_len{__str == nullptr ? 0 : traits_type::length(__str)},
101 _M_str{__str}
102 { }
103
104 constexpr
105 basic_string_view(const _CharT* __str, size_type __len) noexcept
106 : _M_len{__len}, _M_str{__str}
107 { }
108
109 constexpr basic_string_view&
110 operator=(const basic_string_view&) noexcept = default;
111
112 // [string.view.iterators], iterators
113
114 constexpr const_iterator
115 begin() const noexcept
116 { return this->_M_str; }
117
118 constexpr const_iterator
119 end() const noexcept
120 { return this->_M_str + this->_M_len; }
121
122 constexpr const_iterator
123 cbegin() const noexcept
124 { return this->_M_str; }
125
126 constexpr const_iterator
127 cend() const noexcept
128 { return this->_M_str + this->_M_len; }
129
130 constexpr const_reverse_iterator
131 rbegin() const noexcept
132 { return const_reverse_iterator(this->end()); }
133
134 constexpr const_reverse_iterator
135 rend() const noexcept
136 { return const_reverse_iterator(this->begin()); }
137
138 constexpr const_reverse_iterator
139 crbegin() const noexcept
140 { return const_reverse_iterator(this->end()); }
141
142 constexpr const_reverse_iterator
143 crend() const noexcept
144 { return const_reverse_iterator(this->begin()); }
145
146 // [string.view.capacity], capacity
147
148 constexpr size_type
149 size() const noexcept
150 { return this->_M_len; }
151
152 constexpr size_type
153 length() const noexcept
154 { return _M_len; }
155
156 constexpr size_type
157 max_size() const noexcept
158 {
159 return (npos - sizeof(size_type) - sizeof(void*))
160 / sizeof(value_type) / 4;
161 }
162
163 [[nodiscard]] constexpr bool
164 empty() const noexcept
165 { return this->_M_len == 0; }
166
167 // [string.view.access], element access
168
169 constexpr const _CharT&
170 operator[](size_type __pos) const noexcept
171 {
172 // TODO: Assert to restore in a way compatible with the constexpr.
173 // __glibcxx_assert(__pos < this->_M_len);
174 return *(this->_M_str + __pos);
175 }
176
177 constexpr const _CharT&
178 at(size_type __pos) const
179 {
180 if (__pos >= _M_len)
181 __throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
182 "(which is %zu) >= this->size() "
183 "(which is %zu)"), __pos, this->size());
184 return *(this->_M_str + __pos);
185 }
186
187 constexpr const _CharT&
188 front() const noexcept
189 {
190 // TODO: Assert to restore in a way compatible with the constexpr.
191 // __glibcxx_assert(this->_M_len > 0);
192 return *this->_M_str;
193 }
194
195 constexpr const _CharT&
196 back() const noexcept
197 {
198 // TODO: Assert to restore in a way compatible with the constexpr.
199 // __glibcxx_assert(this->_M_len > 0);
200 return *(this->_M_str + this->_M_len - 1);
201 }
202
203 constexpr const _CharT*
204 data() const noexcept
205 { return this->_M_str; }
206
207 // [string.view.modifiers], modifiers:
208
209 constexpr void
210 remove_prefix(size_type __n) noexcept
211 {
212 __glibcxx_assert(this->_M_len >= __n);
213 this->_M_str += __n;
214 this->_M_len -= __n;
215 }
216
217 constexpr void
218 remove_suffix(size_type __n) noexcept
219 { this->_M_len -= __n; }
220
221 constexpr void
222 swap(basic_string_view& __sv) noexcept
223 {
224 auto __tmp = *this;
225 *this = __sv;
226 __sv = __tmp;
227 }
228
229
230 // [string.view.ops], string operations:
231
232 size_type
233 copy(_CharT* __str, size_type __n, size_type __pos = 0) const
234 {
235 __glibcxx_requires_string_len(__str, __n);
236 __pos = _M_check(__pos, "basic_string_view::copy");
237 const size_type __rlen = std::min(__n, _M_len - __pos);
238 // _GLIBCXX_RESOLVE_LIB_DEFECTS
239 // 2777. basic_string_view::copy should use char_traits::copy
240 traits_type::copy(__str, data() + __pos, __rlen);
241 return __rlen;
242 }
243
244 constexpr basic_string_view
245 substr(size_type __pos = 0, size_type __n = npos) const noexcept(false)
246 {
247 __pos = _M_check(__pos, "basic_string_view::substr");
248 const size_type __rlen = std::min(__n, _M_len - __pos);
249 return basic_string_view{_M_str + __pos, __rlen};
250 }
251
252 constexpr int
253 compare(basic_string_view __str) const noexcept
254 {
255 const size_type __rlen = std::min(this->_M_len, __str._M_len);
256 int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen);
257 if (__ret == 0)
258 __ret = _S_compare(this->_M_len, __str._M_len);
259 return __ret;
260 }
261
262 constexpr int
263 compare(size_type __pos1, size_type __n1, basic_string_view __str) const
264 { return this->substr(__pos1, __n1).compare(__str); }
265
266 constexpr int
267 compare(size_type __pos1, size_type __n1,
268 basic_string_view __str, size_type __pos2, size_type __n2) const
269 {
270 return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
271 }
272
273 constexpr int
274 compare(const _CharT* __str) const noexcept
275 { return this->compare(basic_string_view{__str}); }
276
277 constexpr int
278 compare(size_type __pos1, size_type __n1, const _CharT* __str) const
279 { return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
280
281 constexpr int
282 compare(size_type __pos1, size_type __n1,
283 const _CharT* __str, size_type __n2) const noexcept(false)
284 {
285 return this->substr(__pos1, __n1)
286 .compare(basic_string_view(__str, __n2));
287 }
288
289 constexpr size_type
290 find(basic_string_view __str, size_type __pos = 0) const noexcept
291 { return this->find(__str._M_str, __pos, __str._M_len); }
292
293 constexpr size_type
294 find(_CharT __c, size_type __pos = 0) const noexcept;
295
296 constexpr size_type
297 find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
298
299 constexpr size_type
300 find(const _CharT* __str, size_type __pos = 0) const noexcept
301 { return this->find(__str, __pos, traits_type::length(__str)); }
302
303 constexpr size_type
304 rfind(basic_string_view __str, size_type __pos = npos) const noexcept
305 { return this->rfind(__str._M_str, __pos, __str._M_len); }
306
307 constexpr size_type
308 rfind(_CharT __c, size_type __pos = npos) const noexcept;
309
310 constexpr size_type
311 rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
312
313 constexpr size_type
314 rfind(const _CharT* __str, size_type __pos = npos) const noexcept
315 { return this->rfind(__str, __pos, traits_type::length(__str)); }
316
317 constexpr size_type
318 find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
319 { return this->find_first_of(__str._M_str, __pos, __str._M_len); }
320
321 constexpr size_type
322 find_first_of(_CharT __c, size_type __pos = 0) const noexcept
323 { return this->find(__c, __pos); }
324
325 constexpr size_type
326 find_first_of(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
327
328 constexpr size_type
329 find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
330 { return this->find_first_of(__str, __pos, traits_type::length(__str)); }
331
332 constexpr size_type
333 find_last_of(basic_string_view __str,
334 size_type __pos = npos) const noexcept
335 { return this->find_last_of(__str._M_str, __pos, __str._M_len); }
336
337 constexpr size_type
338 find_last_of(_CharT __c, size_type __pos=npos) const noexcept
339 { return this->rfind(__c, __pos); }
340
341 constexpr size_type
342 find_last_of(const _CharT* __str, size_type __pos,
343 size_type __n) const noexcept;
344
345 constexpr size_type
346 find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
347 { return this->find_last_of(__str, __pos, traits_type::length(__str)); }
348
349 constexpr size_type
350 find_first_not_of(basic_string_view __str,
351 size_type __pos = 0) const noexcept
352 { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
353
354 constexpr size_type
355 find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
356
357 constexpr size_type
358 find_first_not_of(const _CharT* __str,
359 size_type __pos, size_type __n) const noexcept;
360
361 constexpr size_type
362 find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
363 {
364 return this->find_first_not_of(__str, __pos,
365 traits_type::length(__str));
366 }
367
368 constexpr size_type
369 find_last_not_of(basic_string_view __str,
370 size_type __pos = npos) const noexcept
371 { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
372
373 constexpr size_type
374 find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
375
376 constexpr size_type
377 find_last_not_of(const _CharT* __str,
378 size_type __pos, size_type __n) const noexcept;
379
380 constexpr size_type
381 find_last_not_of(const _CharT* __str,
382 size_type __pos = npos) const noexcept
383 {
384 return this->find_last_not_of(__str, __pos,
385 traits_type::length(__str));
386 }
387
388 constexpr size_type
389 _M_check(size_type __pos, const char* __s) const noexcept(false)
390 {
391 if (__pos > this->size())
392 __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > "
393 "this->size() (which is %zu)"),
394 __s, __pos, this->size());
395 return __pos;
396 }
397
398 // NB: _M_limit doesn't check for a bad __pos value.
399 constexpr size_type
400 _M_limit(size_type __pos, size_type __off) const noexcept
401 {
402 const bool __testoff = __off < this->size() - __pos;
403 return __testoff ? __off : this->size() - __pos;
404 }
405
406 private:
407
408 static constexpr int
409 _S_compare(size_type __n1, size_type __n2) noexcept
410 {
411 const difference_type __diff = __n1 - __n2;
412 if (__diff > std::numeric_limits<int>::max())
413 return std::numeric_limits<int>::max();
414 if (__diff < std::numeric_limits<int>::min())
415 return std::numeric_limits<int>::min();
416 return static_cast<int>(__diff);
417 }
418
419 size_t _M_len;
420 const _CharT* _M_str;
421 };
422
423 // [string.view.comparison], non-member basic_string_view comparison function
424
425 namespace __detail
426 {
427 // Identity transform to create a non-deduced context, so that only one
428 // argument participates in template argument deduction and the other
429 // argument gets implicitly converted to the deduced type. See n3766.html.
430 template<typename _Tp>
431 using __idt = common_type_t<_Tp>;
432 }
433
434 template<typename _CharT, typename _Traits>
435 constexpr bool
436 operator==(basic_string_view<_CharT, _Traits> __x,
437 basic_string_view<_CharT, _Traits> __y) noexcept
438 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
439
440 template<typename _CharT, typename _Traits>
441 constexpr bool
442 operator==(basic_string_view<_CharT, _Traits> __x,
443 __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
444 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
445
446 template<typename _CharT, typename _Traits>
447 constexpr bool
448 operator==(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
449 basic_string_view<_CharT, _Traits> __y) noexcept
450 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
451
452 template<typename _CharT, typename _Traits>
453 constexpr bool
454 operator!=(basic_string_view<_CharT, _Traits> __x,
455 basic_string_view<_CharT, _Traits> __y) noexcept
456 { return !(__x == __y); }
457
458 template<typename _CharT, typename _Traits>
459 constexpr bool
460 operator!=(basic_string_view<_CharT, _Traits> __x,
461 __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
462 { return !(__x == __y); }
463
464 template<typename _CharT, typename _Traits>
465 constexpr bool
466 operator!=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
467 basic_string_view<_CharT, _Traits> __y) noexcept
468 { return !(__x == __y); }
469
470 template<typename _CharT, typename _Traits>
471 constexpr bool
472 operator< (basic_string_view<_CharT, _Traits> __x,
473 basic_string_view<_CharT, _Traits> __y) noexcept
474 { return __x.compare(__y) < 0; }
475
476 template<typename _CharT, typename _Traits>
477 constexpr bool
478 operator< (basic_string_view<_CharT, _Traits> __x,
479 __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
480 { return __x.compare(__y) < 0; }
481
482 template<typename _CharT, typename _Traits>
483 constexpr bool
484 operator< (__detail::__idt<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 basic_string_view<_CharT, _Traits> __y) noexcept
492 { return __x.compare(__y) > 0; }
493
494 template<typename _CharT, typename _Traits>
495 constexpr bool
496 operator> (basic_string_view<_CharT, _Traits> __x,
497 __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
498 { return __x.compare(__y) > 0; }
499
500 template<typename _CharT, typename _Traits>
501 constexpr bool
502 operator> (__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
503 basic_string_view<_CharT, _Traits> __y) noexcept
504 { return __x.compare(__y) > 0; }
505
506 template<typename _CharT, typename _Traits>
507 constexpr bool
508 operator<=(basic_string_view<_CharT, _Traits> __x,
509 basic_string_view<_CharT, _Traits> __y) noexcept
510 { return __x.compare(__y) <= 0; }
511
512 template<typename _CharT, typename _Traits>
513 constexpr bool
514 operator<=(basic_string_view<_CharT, _Traits> __x,
515 __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
516 { return __x.compare(__y) <= 0; }
517
518 template<typename _CharT, typename _Traits>
519 constexpr bool
520 operator<=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
521 basic_string_view<_CharT, _Traits> __y) noexcept
522 { return __x.compare(__y) <= 0; }
523
524 template<typename _CharT, typename _Traits>
525 constexpr bool
526 operator>=(basic_string_view<_CharT, _Traits> __x,
527 basic_string_view<_CharT, _Traits> __y) noexcept
528 { return __x.compare(__y) >= 0; }
529
530 template<typename _CharT, typename _Traits>
531 constexpr bool
532 operator>=(basic_string_view<_CharT, _Traits> __x,
533 __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept
534 { return __x.compare(__y) >= 0; }
535
536 template<typename _CharT, typename _Traits>
537 constexpr bool
538 operator>=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x,
539 basic_string_view<_CharT, _Traits> __y) noexcept
540 { return __x.compare(__y) >= 0; }
541
542 // [string.view.io], Inserters and extractors
543 template<typename _CharT, typename _Traits>
544 inline basic_ostream<_CharT, _Traits>&
545 operator<<(basic_ostream<_CharT, _Traits>& __os,
546 basic_string_view<_CharT,_Traits> __str)
547 { return __ostream_insert(__os, __str.data(), __str.size()); }
548
549
550 // basic_string_view typedef names
551
552 using string_view = basic_string_view<char>;
553#ifdef _GLIBCXX_USE_WCHAR_T
554 using wstring_view = basic_string_view<wchar_t>;
555#endif
556#ifdef _GLIBCXX_USE_C99_STDINT_TR1
557 using u16string_view = basic_string_view<char16_t>;
558 using u32string_view = basic_string_view<char32_t>;
559#endif
560
561 // [string.view.hash], hash support:
562
563 template<typename _Tp>
564 struct hash;
565
566 template<>
567 struct hash<string_view>
568 : public __hash_base<size_t, string_view>
569 {
570 size_t
571 operator()(const string_view& __str) const noexcept
572 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
573 };
574
575 template<>
576 struct __is_fast_hash<hash<string_view>> : std::false_type
577 { };
578
579#ifdef _GLIBCXX_USE_WCHAR_T
580 template<>
581 struct hash<wstring_view>
582 : public __hash_base<size_t, wstring>
583 {
584 size_t
585 operator()(const wstring_view& __s) const noexcept
586 { return std::_Hash_impl::hash(__s.data(),
587 __s.length() * sizeof(wchar_t)); }
588 };
589
590 template<>
591 struct __is_fast_hash<hash<wstring_view>> : std::false_type
592 { };
593#endif
594
595#ifdef _GLIBCXX_USE_C99_STDINT_TR1
596 template<>
597 struct hash<u16string_view>
598 : public __hash_base<size_t, u16string_view>
599 {
600 size_t
601 operator()(const u16string_view& __s) const noexcept
602 { return std::_Hash_impl::hash(__s.data(),
603 __s.length() * sizeof(char16_t)); }
604 };
605
606 template<>
607 struct __is_fast_hash<hash<u16string_view>> : std::false_type
608 { };
609
610 template<>
611 struct hash<u32string_view>
612 : public __hash_base<size_t, u32string_view>
613 {
614 size_t
615 operator()(const u32string_view& __s) const noexcept
616 { return std::_Hash_impl::hash(__s.data(),
617 __s.length() * sizeof(char32_t)); }
618 };
619
620 template<>
621 struct __is_fast_hash<hash<u32string_view>> : std::false_type
622 { };
623#endif
624
625 inline namespace literals
626 {
627 inline namespace string_view_literals
628 {
629#pragma GCC diagnostic push
630#pragma GCC diagnostic ignored "-Wliteral-suffix"
631 inline constexpr basic_string_view<char>
632 operator""sv(const char* __str, size_t __len) noexcept
633 { return basic_string_view<char>{__str, __len}; }
634
635#ifdef _GLIBCXX_USE_WCHAR_T
636 inline constexpr basic_string_view<wchar_t>
637 operator""sv(const wchar_t* __str, size_t __len) noexcept
638 { return basic_string_view<wchar_t>{__str, __len}; }
639#endif
640
641#ifdef _GLIBCXX_USE_C99_STDINT_TR1
642 inline constexpr basic_string_view<char16_t>
643 operator""sv(const char16_t* __str, size_t __len) noexcept
644 { return basic_string_view<char16_t>{__str, __len}; }
645
646 inline constexpr basic_string_view<char32_t>
647 operator""sv(const char32_t* __str, size_t __len) noexcept
648 { return basic_string_view<char32_t>{__str, __len}; }
649#endif
650#pragma GCC diagnostic pop
651 } // namespace string_literals
652 } // namespace literals
653
654_GLIBCXX_END_NAMESPACE_VERSION
655} // namespace std
656
657#include <bits/string_view.tcc>
658
659#endif // __cplusplus <= 201402L
660
661#endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW
662