libstdc++
string_view
Go to the documentation of this file.
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 
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 include/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 <bits/char_traits.h>
41 #include <bits/functexcept.h>
42 #include <bits/functional_hash.h>
43 #include <bits/range_access.h>
44 #include <bits/stl_algobase.h>
45 #include <ext/numeric_traits.h>
46 
47 #if __cplusplus >= 202002L
48 # include <bits/ranges_base.h>
49 #endif
50 
51 #if _GLIBCXX_HOSTED
52 # include <iosfwd>
53 # include <bits/ostream_insert.h>
54 #endif
55 
56 namespace std _GLIBCXX_VISIBILITY(default)
57 {
58 _GLIBCXX_BEGIN_NAMESPACE_VERSION
59 
60 #if _GLIBCXX_HOSTED
61 # define __cpp_lib_string_view 201803L
62 #endif
63 
64 #if __cplusplus > 201703L
65 # define __cpp_lib_constexpr_string_view 201811L
66 #endif
67 
68  // Helper for basic_string and basic_string_view members.
69  constexpr size_t
70  __sv_check(size_t __size, size_t __pos, const char* __s)
71  {
72  if (__pos > __size)
73  __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > __size "
74  "(which is %zu)"), __s, __pos, __size);
75  return __pos;
76  }
77 
78  // Helper for basic_string members.
79  // NB: __sv_limit doesn't check for a bad __pos value.
80  constexpr size_t
81  __sv_limit(size_t __size, size_t __pos, size_t __off) noexcept
82  {
83  const bool __testoff = __off < __size - __pos;
84  return __testoff ? __off : __size - __pos;
85  }
86 
87  /**
88  * @class basic_string_view <string_view>
89  * @brief A non-owning reference to a string.
90  *
91  * @ingroup strings
92  * @ingroup sequences
93  *
94  * @tparam _CharT Type of character
95  * @tparam _Traits Traits for character type, defaults to
96  * char_traits<_CharT>.
97  *
98  * A basic_string_view looks like this:
99  *
100  * @code
101  * _CharT* _M_str
102  * size_t _M_len
103  * @endcode
104  */
105  template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
106  class basic_string_view
107  {
108  static_assert(!is_array_v<_CharT>);
109  static_assert(is_trivial_v<_CharT> && is_standard_layout_v<_CharT>);
110  static_assert(is_same_v<_CharT, typename _Traits::char_type>);
111 
112  public:
113 
114  // types
115  using traits_type = _Traits;
116  using value_type = _CharT;
117  using pointer = value_type*;
118  using const_pointer = const value_type*;
119  using reference = value_type&;
120  using const_reference = const value_type&;
121  using const_iterator = const value_type*;
122  using iterator = const_iterator;
123  using const_reverse_iterator = std::reverse_iterator<const_iterator>;
124  using reverse_iterator = const_reverse_iterator;
125  using size_type = size_t;
126  using difference_type = ptrdiff_t;
127  static constexpr size_type npos = size_type(-1);
128 
129  // [string.view.cons], construction and assignment
130 
131  constexpr
132  basic_string_view() noexcept
133  : _M_len{0}, _M_str{nullptr}
134  { }
135 
136  constexpr basic_string_view(const basic_string_view&) noexcept = default;
137 
138  [[__gnu__::__nonnull__]]
139  constexpr
140  basic_string_view(const _CharT* __str) noexcept
141  : _M_len{traits_type::length(__str)},
142  _M_str{__str}
143  { }
144 
145  constexpr
146  basic_string_view(const _CharT* __str, size_type __len) noexcept
147  : _M_len{__len}, _M_str{__str}
148  { }
149 
150 #if __cplusplus >= 202002L && __cpp_lib_concepts
151  template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
152  requires same_as<iter_value_t<_It>, _CharT>
153  && (!convertible_to<_End, size_type>)
154  constexpr
155  basic_string_view(_It __first, _End __last)
156  noexcept(noexcept(__last - __first))
157  : _M_len(__last - __first), _M_str(std::to_address(__first))
158  { }
159 
160 #if __cplusplus > 202002L
161  template<typename _Range, typename _DRange = remove_cvref_t<_Range>>
162  requires (!is_same_v<_DRange, basic_string_view>)
163  && ranges::contiguous_range<_Range>
164  && ranges::sized_range<_Range>
165  && is_same_v<ranges::range_value_t<_Range>, _CharT>
166  && (!is_convertible_v<_Range, const _CharT*>)
167  && (!requires (_DRange& __d) {
168  __d.operator ::std::basic_string_view<_CharT, _Traits>();
169  })
170  constexpr explicit
171  basic_string_view(_Range&& __r)
172  noexcept(noexcept(ranges::size(__r)) && noexcept(ranges::data(__r)))
173  : _M_len(ranges::size(__r)), _M_str(ranges::data(__r))
174  { }
175 
176  basic_string_view(nullptr_t) = delete;
177 #endif // C++23
178 #endif // C++20
179 
180  constexpr basic_string_view&
181  operator=(const basic_string_view&) noexcept = default;
182 
183  // [string.view.iterators], iterator support
184 
185  [[nodiscard]]
186  constexpr const_iterator
187  begin() const noexcept
188  { return this->_M_str; }
189 
190  [[nodiscard]]
191  constexpr const_iterator
192  end() const noexcept
193  { return this->_M_str + this->_M_len; }
194 
195  [[nodiscard]]
196  constexpr const_iterator
197  cbegin() const noexcept
198  { return this->_M_str; }
199 
200  [[nodiscard]]
201  constexpr const_iterator
202  cend() const noexcept
203  { return this->_M_str + this->_M_len; }
204 
205  [[nodiscard]]
206  constexpr const_reverse_iterator
207  rbegin() const noexcept
208  { return const_reverse_iterator(this->end()); }
209 
210  [[nodiscard]]
211  constexpr const_reverse_iterator
212  rend() const noexcept
213  { return const_reverse_iterator(this->begin()); }
214 
215  [[nodiscard]]
216  constexpr const_reverse_iterator
217  crbegin() const noexcept
218  { return const_reverse_iterator(this->end()); }
219 
220  [[nodiscard]]
221  constexpr const_reverse_iterator
222  crend() const noexcept
223  { return const_reverse_iterator(this->begin()); }
224 
225  // [string.view.capacity], capacity
226 
227  [[nodiscard]]
228  constexpr size_type
229  size() const noexcept
230  { return this->_M_len; }
231 
232  [[nodiscard]]
233  constexpr size_type
234  length() const noexcept
235  { return _M_len; }
236 
237  [[nodiscard]]
238  constexpr size_type
239  max_size() const noexcept
240  {
241  return (npos - sizeof(size_type) - sizeof(void*))
242  / sizeof(value_type) / 4;
243  }
244 
245  [[nodiscard]]
246  constexpr bool
247  empty() const noexcept
248  { return this->_M_len == 0; }
249 
250  // [string.view.access], element access
251 
252  [[nodiscard]]
253  constexpr const_reference
254  operator[](size_type __pos) const noexcept
255  {
256  __glibcxx_assert(__pos < this->_M_len);
257  return *(this->_M_str + __pos);
258  }
259 
260  [[nodiscard]]
261  constexpr const_reference
262  at(size_type __pos) const
263  {
264  if (__pos >= _M_len)
265  __throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
266  "(which is %zu) >= this->size() "
267  "(which is %zu)"), __pos, this->size());
268  return *(this->_M_str + __pos);
269  }
270 
271  [[nodiscard]]
272  constexpr const_reference
273  front() const noexcept
274  {
275  __glibcxx_assert(this->_M_len > 0);
276  return *this->_M_str;
277  }
278 
279  [[nodiscard]]
280  constexpr const_reference
281  back() const noexcept
282  {
283  __glibcxx_assert(this->_M_len > 0);
284  return *(this->_M_str + this->_M_len - 1);
285  }
286 
287  [[nodiscard]]
288  constexpr const_pointer
289  data() const noexcept
290  { return this->_M_str; }
291 
292  // [string.view.modifiers], modifiers:
293 
294  constexpr void
295  remove_prefix(size_type __n) noexcept
296  {
297  __glibcxx_assert(this->_M_len >= __n);
298  this->_M_str += __n;
299  this->_M_len -= __n;
300  }
301 
302  constexpr void
303  remove_suffix(size_type __n) noexcept
304  {
305  __glibcxx_assert(this->_M_len >= __n);
306  this->_M_len -= __n;
307  }
308 
309  constexpr void
310  swap(basic_string_view& __sv) noexcept
311  {
312  auto __tmp = *this;
313  *this = __sv;
314  __sv = __tmp;
315  }
316 
317  // [string.view.ops], string operations:
318 
319  _GLIBCXX20_CONSTEXPR
320  size_type
321  copy(_CharT* __str, size_type __n, size_type __pos = 0) const
322  {
323  __glibcxx_requires_string_len(__str, __n);
324  __pos = std::__sv_check(size(), __pos, "basic_string_view::copy");
325  const size_type __rlen = std::min<size_t>(__n, _M_len - __pos);
326  // _GLIBCXX_RESOLVE_LIB_DEFECTS
327  // 2777. basic_string_view::copy should use char_traits::copy
328  traits_type::copy(__str, data() + __pos, __rlen);
329  return __rlen;
330  }
331 
332  [[nodiscard]]
333  constexpr basic_string_view
334  substr(size_type __pos = 0, size_type __n = npos) const noexcept(false)
335  {
336  __pos = std::__sv_check(size(), __pos, "basic_string_view::substr");
337  const size_type __rlen = std::min<size_t>(__n, _M_len - __pos);
338  return basic_string_view{_M_str + __pos, __rlen};
339  }
340 
341  [[nodiscard]]
342  constexpr int
343  compare(basic_string_view __str) const noexcept
344  {
345  const size_type __rlen = std::min(this->_M_len, __str._M_len);
346  int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen);
347  if (__ret == 0)
348  __ret = _S_compare(this->_M_len, __str._M_len);
349  return __ret;
350  }
351 
352  [[nodiscard]]
353  constexpr int
354  compare(size_type __pos1, size_type __n1, basic_string_view __str) const
355  { return this->substr(__pos1, __n1).compare(__str); }
356 
357  [[nodiscard]]
358  constexpr int
359  compare(size_type __pos1, size_type __n1,
360  basic_string_view __str, size_type __pos2, size_type __n2) const
361  {
362  return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
363  }
364 
365  [[nodiscard, __gnu__::__nonnull__]]
366  constexpr int
367  compare(const _CharT* __str) const noexcept
368  { return this->compare(basic_string_view{__str}); }
369 
370  [[nodiscard, __gnu__::__nonnull__]]
371  constexpr int
372  compare(size_type __pos1, size_type __n1, const _CharT* __str) const
373  { return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
374 
375  [[nodiscard]]
376  constexpr int
377  compare(size_type __pos1, size_type __n1,
378  const _CharT* __str, size_type __n2) const noexcept(false)
379  {
380  return this->substr(__pos1, __n1)
381  .compare(basic_string_view(__str, __n2));
382  }
383 
384 #if __cplusplus > 201703L
385 #define __cpp_lib_starts_ends_with 201711L
386  [[nodiscard]]
387  constexpr bool
388  starts_with(basic_string_view __x) const noexcept
389  { return this->substr(0, __x.size()) == __x; }
390 
391  [[nodiscard]]
392  constexpr bool
393  starts_with(_CharT __x) const noexcept
394  { return !this->empty() && traits_type::eq(this->front(), __x); }
395 
396  [[nodiscard, __gnu__::__nonnull__]]
397  constexpr bool
398  starts_with(const _CharT* __x) const noexcept
399  { return this->starts_with(basic_string_view(__x)); }
400 
401  [[nodiscard]]
402  constexpr bool
403  ends_with(basic_string_view __x) const noexcept
404  {
405  const auto __len = this->size();
406  const auto __xlen = __x.size();
407  return __len >= __xlen
408  && traits_type::compare(end() - __xlen, __x.data(), __xlen) == 0;
409  }
410 
411  [[nodiscard]]
412  constexpr bool
413  ends_with(_CharT __x) const noexcept
414  { return !this->empty() && traits_type::eq(this->back(), __x); }
415 
416  [[nodiscard, __gnu__::__nonnull__]]
417  constexpr bool
418  ends_with(const _CharT* __x) const noexcept
419  { return this->ends_with(basic_string_view(__x)); }
420 #endif // C++20
421 
422 #if __cplusplus > 202002L
423 #if _GLIBCXX_HOSTED
424  // This FTM is not freestanding as it also implies matching <string>
425  // support, and <string> is omitted from the freestanding subset.
426 # define __cpp_lib_string_contains 202011L
427 #endif // HOSTED
428  [[nodiscard]]
429  constexpr bool
430  contains(basic_string_view __x) const noexcept
431  { return this->find(__x) != npos; }
432 
433  [[nodiscard]]
434  constexpr bool
435  contains(_CharT __x) const noexcept
436  { return this->find(__x) != npos; }
437 
438  [[nodiscard, __gnu__::__nonnull__]]
439  constexpr bool
440  contains(const _CharT* __x) const noexcept
441  { return this->find(__x) != npos; }
442 #endif // C++23
443 
444  // [string.view.find], searching
445 
446  [[nodiscard]]
447  constexpr size_type
448  find(basic_string_view __str, size_type __pos = 0) const noexcept
449  { return this->find(__str._M_str, __pos, __str._M_len); }
450 
451  [[nodiscard]]
452  constexpr size_type
453  find(_CharT __c, size_type __pos = 0) const noexcept;
454 
455  [[nodiscard]]
456  constexpr size_type
457  find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
458 
459  [[nodiscard, __gnu__::__nonnull__]]
460  constexpr size_type
461  find(const _CharT* __str, size_type __pos = 0) const noexcept
462  { return this->find(__str, __pos, traits_type::length(__str)); }
463 
464  [[nodiscard]]
465  constexpr size_type
466  rfind(basic_string_view __str, size_type __pos = npos) const noexcept
467  { return this->rfind(__str._M_str, __pos, __str._M_len); }
468 
469  [[nodiscard]]
470  constexpr size_type
471  rfind(_CharT __c, size_type __pos = npos) const noexcept;
472 
473  [[nodiscard]]
474  constexpr size_type
475  rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
476 
477  [[nodiscard, __gnu__::__nonnull__]]
478  constexpr size_type
479  rfind(const _CharT* __str, size_type __pos = npos) const noexcept
480  { return this->rfind(__str, __pos, traits_type::length(__str)); }
481 
482  [[nodiscard]]
483  constexpr size_type
484  find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
485  { return this->find_first_of(__str._M_str, __pos, __str._M_len); }
486 
487  [[nodiscard]]
488  constexpr size_type
489  find_first_of(_CharT __c, size_type __pos = 0) const noexcept
490  { return this->find(__c, __pos); }
491 
492  [[nodiscard]]
493  constexpr size_type
494  find_first_of(const _CharT* __str, size_type __pos,
495  size_type __n) const noexcept;
496 
497  [[nodiscard, __gnu__::__nonnull__]]
498  constexpr size_type
499  find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
500  { return this->find_first_of(__str, __pos, traits_type::length(__str)); }
501 
502  [[nodiscard]]
503  constexpr size_type
504  find_last_of(basic_string_view __str,
505  size_type __pos = npos) const noexcept
506  { return this->find_last_of(__str._M_str, __pos, __str._M_len); }
507 
508  [[nodiscard]]
509  constexpr size_type
510  find_last_of(_CharT __c, size_type __pos=npos) const noexcept
511  { return this->rfind(__c, __pos); }
512 
513  [[nodiscard]]
514  constexpr size_type
515  find_last_of(const _CharT* __str, size_type __pos,
516  size_type __n) const noexcept;
517 
518  [[nodiscard, __gnu__::__nonnull__]]
519  constexpr size_type
520  find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
521  { return this->find_last_of(__str, __pos, traits_type::length(__str)); }
522 
523  [[nodiscard]]
524  constexpr size_type
525  find_first_not_of(basic_string_view __str,
526  size_type __pos = 0) const noexcept
527  { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
528 
529  [[nodiscard]]
530  constexpr size_type
531  find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
532 
533  [[nodiscard]]
534  constexpr size_type
535  find_first_not_of(const _CharT* __str,
536  size_type __pos, size_type __n) const noexcept;
537 
538  [[nodiscard, __gnu__::__nonnull__]]
539  constexpr size_type
540  find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
541  {
542  return this->find_first_not_of(__str, __pos,
543  traits_type::length(__str));
544  }
545 
546  [[nodiscard]]
547  constexpr size_type
548  find_last_not_of(basic_string_view __str,
549  size_type __pos = npos) const noexcept
550  { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
551 
552  [[nodiscard]]
553  constexpr size_type
554  find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
555 
556  [[nodiscard]]
557  constexpr size_type
558  find_last_not_of(const _CharT* __str,
559  size_type __pos, size_type __n) const noexcept;
560 
561  [[nodiscard, __gnu__::__nonnull__]]
562  constexpr size_type
563  find_last_not_of(const _CharT* __str,
564  size_type __pos = npos) const noexcept
565  {
566  return this->find_last_not_of(__str, __pos,
567  traits_type::length(__str));
568  }
569 
570  private:
571 
572  static constexpr int
573  _S_compare(size_type __n1, size_type __n2) noexcept
574  {
575  using __limits = __gnu_cxx::__int_traits<int>;
576  const difference_type __diff = __n1 - __n2;
577  if (__diff > __limits::__max)
578  return __limits::__max;
579  if (__diff < __limits::__min)
580  return __limits::__min;
581  return static_cast<int>(__diff);
582  }
583 
584  size_t _M_len;
585  const _CharT* _M_str;
586  };
587 
588 #if __cplusplus > 201703L && __cpp_lib_concepts && __cpp_deduction_guides
589  template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
590  basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
591 
592 #if __cplusplus > 202002L
593  template<ranges::contiguous_range _Range>
594  basic_string_view(_Range&&)
595  -> basic_string_view<ranges::range_value_t<_Range>>;
596 #endif
597 #endif
598 
599  // [string.view.comparison], non-member basic_string_view comparison function
600 
601  // Several of these functions use type_identity_t to create a non-deduced
602  // context, so that only one argument participates in template argument
603  // deduction and the other argument gets implicitly converted to the deduced
604  // type (see N3766).
605 
606  template<typename _CharT, typename _Traits>
607  [[nodiscard]]
608  constexpr bool
609  operator==(basic_string_view<_CharT, _Traits> __x,
610  basic_string_view<_CharT, _Traits> __y) noexcept
611  { return __x.size() == __y.size() && __x.compare(__y) == 0; }
612 
613  template<typename _CharT, typename _Traits>
614  [[nodiscard]]
615  constexpr bool
616  operator==(basic_string_view<_CharT, _Traits> __x,
617  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
618  noexcept
619  { return __x.size() == __y.size() && __x.compare(__y) == 0; }
620 
621 #if __cpp_lib_three_way_comparison
622  template<typename _CharT, typename _Traits>
623  [[nodiscard]]
624  constexpr auto
625  operator<=>(basic_string_view<_CharT, _Traits> __x,
626  basic_string_view<_CharT, _Traits> __y) noexcept
627  -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
628  { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
629 
630  template<typename _CharT, typename _Traits>
631  [[nodiscard]]
632  constexpr auto
633  operator<=>(basic_string_view<_CharT, _Traits> __x,
634  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
635  noexcept
636  -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
637  { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
638 #else
639  template<typename _CharT, typename _Traits>
640  [[nodiscard]]
641  constexpr bool
642  operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
643  basic_string_view<_CharT, _Traits> __y) noexcept
644  { return __x.size() == __y.size() && __x.compare(__y) == 0; }
645 
646  template<typename _CharT, typename _Traits>
647  [[nodiscard]]
648  constexpr bool
649  operator!=(basic_string_view<_CharT, _Traits> __x,
650  basic_string_view<_CharT, _Traits> __y) noexcept
651  { return !(__x == __y); }
652 
653  template<typename _CharT, typename _Traits>
654  [[nodiscard]]
655  constexpr bool
656  operator!=(basic_string_view<_CharT, _Traits> __x,
657  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
658  noexcept
659  { return !(__x == __y); }
660 
661  template<typename _CharT, typename _Traits>
662  [[nodiscard]]
663  constexpr bool
664  operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
665  basic_string_view<_CharT, _Traits> __y) noexcept
666  { return !(__x == __y); }
667 
668  template<typename _CharT, typename _Traits>
669  [[nodiscard]]
670  constexpr bool
671  operator< (basic_string_view<_CharT, _Traits> __x,
672  basic_string_view<_CharT, _Traits> __y) noexcept
673  { return __x.compare(__y) < 0; }
674 
675  template<typename _CharT, typename _Traits>
676  [[nodiscard]]
677  constexpr bool
678  operator< (basic_string_view<_CharT, _Traits> __x,
679  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
680  noexcept
681  { return __x.compare(__y) < 0; }
682 
683  template<typename _CharT, typename _Traits>
684  [[nodiscard]]
685  constexpr bool
686  operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
687  basic_string_view<_CharT, _Traits> __y) noexcept
688  { return __x.compare(__y) < 0; }
689 
690  template<typename _CharT, typename _Traits>
691  [[nodiscard]]
692  constexpr bool
693  operator> (basic_string_view<_CharT, _Traits> __x,
694  basic_string_view<_CharT, _Traits> __y) noexcept
695  { return __x.compare(__y) > 0; }
696 
697  template<typename _CharT, typename _Traits>
698  [[nodiscard]]
699  constexpr bool
700  operator> (basic_string_view<_CharT, _Traits> __x,
701  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
702  noexcept
703  { return __x.compare(__y) > 0; }
704 
705  template<typename _CharT, typename _Traits>
706  [[nodiscard]]
707  constexpr bool
708  operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
709  basic_string_view<_CharT, _Traits> __y) noexcept
710  { return __x.compare(__y) > 0; }
711 
712  template<typename _CharT, typename _Traits>
713  [[nodiscard]]
714  constexpr bool
715  operator<=(basic_string_view<_CharT, _Traits> __x,
716  basic_string_view<_CharT, _Traits> __y) noexcept
717  { return __x.compare(__y) <= 0; }
718 
719  template<typename _CharT, typename _Traits>
720  [[nodiscard]]
721  constexpr bool
722  operator<=(basic_string_view<_CharT, _Traits> __x,
723  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
724  noexcept
725  { return __x.compare(__y) <= 0; }
726 
727  template<typename _CharT, typename _Traits>
728  [[nodiscard]]
729  constexpr bool
730  operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
731  basic_string_view<_CharT, _Traits> __y) noexcept
732  { return __x.compare(__y) <= 0; }
733 
734  template<typename _CharT, typename _Traits>
735  [[nodiscard]]
736  constexpr bool
737  operator>=(basic_string_view<_CharT, _Traits> __x,
738  basic_string_view<_CharT, _Traits> __y) noexcept
739  { return __x.compare(__y) >= 0; }
740 
741  template<typename _CharT, typename _Traits>
742  [[nodiscard]]
743  constexpr bool
744  operator>=(basic_string_view<_CharT, _Traits> __x,
745  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
746  noexcept
747  { return __x.compare(__y) >= 0; }
748 
749  template<typename _CharT, typename _Traits>
750  [[nodiscard]]
751  constexpr bool
752  operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
753  basic_string_view<_CharT, _Traits> __y) noexcept
754  { return __x.compare(__y) >= 0; }
755 #endif // three-way comparison
756 
757 #if _GLIBCXX_HOSTED
758  // [string.view.io], Inserters and extractors
759  template<typename _CharT, typename _Traits>
760  inline basic_ostream<_CharT, _Traits>&
761  operator<<(basic_ostream<_CharT, _Traits>& __os,
762  basic_string_view<_CharT,_Traits> __str)
763  { return __ostream_insert(__os, __str.data(), __str.size()); }
764 #endif // HOSTED
765 
766  // basic_string_view typedef names
767 
768  using string_view = basic_string_view<char>;
769  using wstring_view = basic_string_view<wchar_t>;
770 #ifdef _GLIBCXX_USE_CHAR8_T
771  using u8string_view = basic_string_view<char8_t>;
772 #endif
773  using u16string_view = basic_string_view<char16_t>;
774  using u32string_view = basic_string_view<char32_t>;
775 
776  // [string.view.hash], hash support:
777 
778  template<typename _Tp>
779  struct hash;
780 
781  template<>
782  struct hash<string_view>
783  : public __hash_base<size_t, string_view>
784  {
785  [[nodiscard]]
786  size_t
787  operator()(const string_view& __str) const noexcept
788  { return std::_Hash_impl::hash(__str.data(), __str.length()); }
789  };
790 
791  template<>
792  struct __is_fast_hash<hash<string_view>> : std::false_type
793  { };
794 
795  template<>
796  struct hash<wstring_view>
797  : public __hash_base<size_t, wstring_view>
798  {
799  [[nodiscard]]
800  size_t
801  operator()(const wstring_view& __s) const noexcept
802  { return std::_Hash_impl::hash(__s.data(),
803  __s.length() * sizeof(wchar_t)); }
804  };
805 
806  template<>
807  struct __is_fast_hash<hash<wstring_view>> : std::false_type
808  { };
809 
810 #ifdef _GLIBCXX_USE_CHAR8_T
811  template<>
812  struct hash<u8string_view>
813  : public __hash_base<size_t, u8string_view>
814  {
815  [[nodiscard]]
816  size_t
817  operator()(const u8string_view& __str) const noexcept
818  { return std::_Hash_impl::hash(__str.data(), __str.length()); }
819  };
820 
821  template<>
822  struct __is_fast_hash<hash<u8string_view>> : std::false_type
823  { };
824 #endif
825 
826  template<>
827  struct hash<u16string_view>
828  : public __hash_base<size_t, u16string_view>
829  {
830  [[nodiscard]]
831  size_t
832  operator()(const u16string_view& __s) const noexcept
833  { return std::_Hash_impl::hash(__s.data(),
834  __s.length() * sizeof(char16_t)); }
835  };
836 
837  template<>
838  struct __is_fast_hash<hash<u16string_view>> : std::false_type
839  { };
840 
841  template<>
842  struct hash<u32string_view>
843  : public __hash_base<size_t, u32string_view>
844  {
845  [[nodiscard]]
846  size_t
847  operator()(const u32string_view& __s) const noexcept
848  { return std::_Hash_impl::hash(__s.data(),
849  __s.length() * sizeof(char32_t)); }
850  };
851 
852  template<>
853  struct __is_fast_hash<hash<u32string_view>> : std::false_type
854  { };
855 
856  inline namespace literals
857  {
858  inline namespace string_view_literals
859  {
860 #pragma GCC diagnostic push
861 #pragma GCC diagnostic ignored "-Wliteral-suffix"
862  inline constexpr basic_string_view<char>
863  operator""sv(const char* __str, size_t __len) noexcept
864  { return basic_string_view<char>{__str, __len}; }
865 
866  inline constexpr basic_string_view<wchar_t>
867  operator""sv(const wchar_t* __str, size_t __len) noexcept
868  { return basic_string_view<wchar_t>{__str, __len}; }
869 
870 #ifdef _GLIBCXX_USE_CHAR8_T
871  inline constexpr basic_string_view<char8_t>
872  operator""sv(const char8_t* __str, size_t __len) noexcept
873  { return basic_string_view<char8_t>{__str, __len}; }
874 #endif
875 
876  inline constexpr basic_string_view<char16_t>
877  operator""sv(const char16_t* __str, size_t __len) noexcept
878  { return basic_string_view<char16_t>{__str, __len}; }
879 
880  inline constexpr basic_string_view<char32_t>
881  operator""sv(const char32_t* __str, size_t __len) noexcept
882  { return basic_string_view<char32_t>{__str, __len}; }
883 
884 #pragma GCC diagnostic pop
885  } // namespace string_literals
886  } // namespace literals
887 
888 #if __cpp_lib_concepts
889  namespace ranges
890  {
891  // Opt-in to borrowed_range concept
892  template<typename _CharT, typename _Traits>
893  inline constexpr bool
894  enable_borrowed_range<basic_string_view<_CharT, _Traits>> = true;
895 
896  // Opt-in to view concept
897  template<typename _CharT, typename _Traits>
898  inline constexpr bool
899  enable_view<basic_string_view<_CharT, _Traits>> = true;
900  }
901 #endif
902 _GLIBCXX_END_NAMESPACE_VERSION
903 } // namespace std
904 
905 #include <bits/string_view.tcc>
906 
907 #endif // __cplusplus <= 201402L
908 
909 #endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW