libstdc++
string_view
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1 // Components for manipulating non-owning sequences of characters -*- C++ -*-
2 
3 // Copyright (C) 2013-2020 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
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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 
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15 
16 // Under Section 7 of GPL version 3, you are granted additional
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18 // 3.1, as published by the Free Software Foundation.
19 
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22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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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 <iosfwd>
41 #include <bits/char_traits.h>
42 #include <bits/functional_hash.h>
43 #include <bits/int_limits.h>
44 #include <bits/range_access.h>
45 #include <bits/ostream_insert.h>
46 
47 namespace std _GLIBCXX_VISIBILITY(default)
48 {
49 _GLIBCXX_BEGIN_NAMESPACE_VERSION
50 
51 #define __cpp_lib_string_view 201803
52 
53  // Helper for basic_string and basic_string_view members.
54  constexpr size_t
55  __sv_check(size_t __size, size_t __pos, const char* __s)
56  {
57  if (__pos > __size)
58  __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > __size "
59  "(which is %zu)"), __s, __pos, __size);
60  return __pos;
61  }
62 
63  // Helper for basic_string members.
64  // NB: __sv_limit doesn't check for a bad __pos value.
65  constexpr size_t
66  __sv_limit(size_t __size, size_t __pos, size_t __off) noexcept
67  {
68  const bool __testoff = __off < __size - __pos;
69  return __testoff ? __off : __size - __pos;
70  }
71 
72  /**
73  * @class basic_string_view <string_view>
74  * @brief A non-owning reference to a string.
75  *
76  * @ingroup strings
77  * @ingroup sequences
78  *
79  * @tparam _CharT Type of character
80  * @tparam _Traits Traits for character type, defaults to
81  * char_traits<_CharT>.
82  *
83  * A basic_string_view looks like this:
84  *
85  * @code
86  * _CharT* _M_str
87  * size_t _M_len
88  * @endcode
89  */
90  template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
91  class basic_string_view
92  {
93  static_assert(!is_array_v<_CharT>);
94  static_assert(is_trivial_v<_CharT> && is_standard_layout_v<_CharT>);
95  static_assert(is_same_v<_CharT, typename _Traits::char_type>);
96 
97  public:
98 
99  // types
100  using traits_type = _Traits;
101  using value_type = _CharT;
102  using pointer = value_type*;
103  using const_pointer = const value_type*;
104  using reference = value_type&;
105  using const_reference = const value_type&;
106  using const_iterator = const value_type*;
107  using iterator = const_iterator;
108  using const_reverse_iterator = std::reverse_iterator<const_iterator>;
109  using reverse_iterator = const_reverse_iterator;
110  using size_type = size_t;
111  using difference_type = ptrdiff_t;
112  static constexpr size_type npos = size_type(-1);
113 
114  // [string.view.cons], construction and assignment
115 
116  constexpr
117  basic_string_view() noexcept
118  : _M_len{0}, _M_str{nullptr}
119  { }
120 
121  constexpr basic_string_view(const basic_string_view&) noexcept = default;
122 
123  __attribute__((__nonnull__)) constexpr
124  basic_string_view(const _CharT* __str) noexcept
125  : _M_len{traits_type::length(__str)},
126  _M_str{__str}
127  { }
128 
129  constexpr
130  basic_string_view(const _CharT* __str, size_type __len) noexcept
131  : _M_len{__len}, _M_str{__str}
132  { }
133 
134 #if __cplusplus > 201703L && __cpp_lib_concepts
135  template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
136  requires same_as<iter_value_t<_It>, _CharT>
137  && (!convertible_to<_End, size_type>)
138  constexpr
139  basic_string_view(_It __first, _End __last)
140  : _M_len(__last - __first), _M_str(std::to_address(__first))
141  { }
142 #endif
143 
144  constexpr basic_string_view&
145  operator=(const basic_string_view&) noexcept = default;
146 
147  // [string.view.iterators], iterator support
148 
149  constexpr const_iterator
150  begin() const noexcept
151  { return this->_M_str; }
152 
153  constexpr const_iterator
154  end() const noexcept
155  { return this->_M_str + this->_M_len; }
156 
157  constexpr const_iterator
158  cbegin() const noexcept
159  { return this->_M_str; }
160 
161  constexpr const_iterator
162  cend() const noexcept
163  { return this->_M_str + this->_M_len; }
164 
165  constexpr const_reverse_iterator
166  rbegin() const noexcept
167  { return const_reverse_iterator(this->end()); }
168 
169  constexpr const_reverse_iterator
170  rend() const noexcept
171  { return const_reverse_iterator(this->begin()); }
172 
173  constexpr const_reverse_iterator
174  crbegin() const noexcept
175  { return const_reverse_iterator(this->end()); }
176 
177  constexpr const_reverse_iterator
178  crend() const noexcept
179  { return const_reverse_iterator(this->begin()); }
180 
181  // [string.view.capacity], capacity
182 
183  constexpr size_type
184  size() const noexcept
185  { return this->_M_len; }
186 
187  constexpr size_type
188  length() const noexcept
189  { return _M_len; }
190 
191  constexpr size_type
192  max_size() const noexcept
193  {
194  return (npos - sizeof(size_type) - sizeof(void*))
195  / sizeof(value_type) / 4;
196  }
197 
198  [[nodiscard]] constexpr bool
199  empty() const noexcept
200  { return this->_M_len == 0; }
201 
202  // [string.view.access], element access
203 
204  constexpr const_reference
205  operator[](size_type __pos) const noexcept
206  {
207  // TODO: Assert to restore in a way compatible with the constexpr.
208  // __glibcxx_assert(__pos < this->_M_len);
209  return *(this->_M_str + __pos);
210  }
211 
212  constexpr const_reference
213  at(size_type __pos) const
214  {
215  if (__pos >= _M_len)
216  __throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
217  "(which is %zu) >= this->size() "
218  "(which is %zu)"), __pos, this->size());
219  return *(this->_M_str + __pos);
220  }
221 
222  constexpr const_reference
223  front() const noexcept
224  {
225  // TODO: Assert to restore in a way compatible with the constexpr.
226  // __glibcxx_assert(this->_M_len > 0);
227  return *this->_M_str;
228  }
229 
230  constexpr const_reference
231  back() const noexcept
232  {
233  // TODO: Assert to restore in a way compatible with the constexpr.
234  // __glibcxx_assert(this->_M_len > 0);
235  return *(this->_M_str + this->_M_len - 1);
236  }
237 
238  constexpr const_pointer
239  data() const noexcept
240  { return this->_M_str; }
241 
242  // [string.view.modifiers], modifiers:
243 
244  constexpr void
245  remove_prefix(size_type __n) noexcept
246  {
247  __glibcxx_assert(this->_M_len >= __n);
248  this->_M_str += __n;
249  this->_M_len -= __n;
250  }
251 
252  constexpr void
253  remove_suffix(size_type __n) noexcept
254  { this->_M_len -= __n; }
255 
256  constexpr void
257  swap(basic_string_view& __sv) noexcept
258  {
259  auto __tmp = *this;
260  *this = __sv;
261  __sv = __tmp;
262  }
263 
264  // [string.view.ops], string operations:
265 
266  size_type
267  copy(_CharT* __str, size_type __n, size_type __pos = 0) const
268  {
269  __glibcxx_requires_string_len(__str, __n);
270  __pos = std::__sv_check(size(), __pos, "basic_string_view::copy");
271  const size_type __rlen = std::min(__n, _M_len - __pos);
272  // _GLIBCXX_RESOLVE_LIB_DEFECTS
273  // 2777. basic_string_view::copy should use char_traits::copy
274  traits_type::copy(__str, data() + __pos, __rlen);
275  return __rlen;
276  }
277 
278  constexpr basic_string_view
279  substr(size_type __pos = 0, size_type __n = npos) const noexcept(false)
280  {
281  __pos = std::__sv_check(size(), __pos, "basic_string_view::substr");
282  const size_type __rlen = std::min(__n, _M_len - __pos);
283  return basic_string_view{_M_str + __pos, __rlen};
284  }
285 
286  constexpr int
287  compare(basic_string_view __str) const noexcept
288  {
289  const size_type __rlen = std::min(this->_M_len, __str._M_len);
290  int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen);
291  if (__ret == 0)
292  __ret = _S_compare(this->_M_len, __str._M_len);
293  return __ret;
294  }
295 
296  constexpr int
297  compare(size_type __pos1, size_type __n1, basic_string_view __str) const
298  { return this->substr(__pos1, __n1).compare(__str); }
299 
300  constexpr int
301  compare(size_type __pos1, size_type __n1,
302  basic_string_view __str, size_type __pos2, size_type __n2) const
303  {
304  return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
305  }
306 
307  __attribute__((__nonnull__)) constexpr int
308  compare(const _CharT* __str) const noexcept
309  { return this->compare(basic_string_view{__str}); }
310 
311  __attribute__((__nonnull__)) 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 noexcept(false)
318  {
319  return this->substr(__pos1, __n1)
320  .compare(basic_string_view(__str, __n2));
321  }
322 
323 #if __cplusplus > 201703L
324  constexpr bool
325  starts_with(basic_string_view __x) const noexcept
326  { return this->substr(0, __x.size()) == __x; }
327 
328  constexpr bool
329  starts_with(_CharT __x) const noexcept
330  { return !this->empty() && traits_type::eq(this->front(), __x); }
331 
332  constexpr bool
333  starts_with(const _CharT* __x) const noexcept
334  { return this->starts_with(basic_string_view(__x)); }
335 
336  constexpr bool
337  ends_with(basic_string_view __x) const noexcept
338  {
339  return this->size() >= __x.size()
340  && this->compare(this->size() - __x.size(), npos, __x) == 0;
341  }
342 
343  constexpr bool
344  ends_with(_CharT __x) const noexcept
345  { return !this->empty() && traits_type::eq(this->back(), __x); }
346 
347  constexpr bool
348  ends_with(const _CharT* __x) const noexcept
349  { return this->ends_with(basic_string_view(__x)); }
350 #endif // C++20
351 
352  // [string.view.find], searching
353 
354  constexpr size_type
355  find(basic_string_view __str, size_type __pos = 0) const noexcept
356  { return this->find(__str._M_str, __pos, __str._M_len); }
357 
358  constexpr size_type
359  find(_CharT __c, size_type __pos = 0) const noexcept;
360 
361  constexpr size_type
362  find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
363 
364  __attribute__((__nonnull__)) constexpr size_type
365  find(const _CharT* __str, size_type __pos = 0) const noexcept
366  { return this->find(__str, __pos, traits_type::length(__str)); }
367 
368  constexpr size_type
369  rfind(basic_string_view __str, size_type __pos = npos) const noexcept
370  { return this->rfind(__str._M_str, __pos, __str._M_len); }
371 
372  constexpr size_type
373  rfind(_CharT __c, size_type __pos = npos) const noexcept;
374 
375  constexpr size_type
376  rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
377 
378  __attribute__((__nonnull__)) constexpr size_type
379  rfind(const _CharT* __str, size_type __pos = npos) const noexcept
380  { return this->rfind(__str, __pos, traits_type::length(__str)); }
381 
382  constexpr size_type
383  find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
384  { return this->find_first_of(__str._M_str, __pos, __str._M_len); }
385 
386  constexpr size_type
387  find_first_of(_CharT __c, size_type __pos = 0) const noexcept
388  { return this->find(__c, __pos); }
389 
390  constexpr size_type
391  find_first_of(const _CharT* __str, size_type __pos,
392  size_type __n) const noexcept;
393 
394  __attribute__((__nonnull__)) constexpr size_type
395  find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
396  { return this->find_first_of(__str, __pos, traits_type::length(__str)); }
397 
398  constexpr size_type
399  find_last_of(basic_string_view __str,
400  size_type __pos = npos) const noexcept
401  { return this->find_last_of(__str._M_str, __pos, __str._M_len); }
402 
403  constexpr size_type
404  find_last_of(_CharT __c, size_type __pos=npos) const noexcept
405  { return this->rfind(__c, __pos); }
406 
407  constexpr size_type
408  find_last_of(const _CharT* __str, size_type __pos,
409  size_type __n) const noexcept;
410 
411  __attribute__((__nonnull__)) constexpr size_type
412  find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
413  { return this->find_last_of(__str, __pos, traits_type::length(__str)); }
414 
415  constexpr size_type
416  find_first_not_of(basic_string_view __str,
417  size_type __pos = 0) const noexcept
418  { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
419 
420  constexpr size_type
421  find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
422 
423  constexpr size_type
424  find_first_not_of(const _CharT* __str,
425  size_type __pos, size_type __n) const noexcept;
426 
427  __attribute__((__nonnull__)) constexpr size_type
428  find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
429  {
430  return this->find_first_not_of(__str, __pos,
431  traits_type::length(__str));
432  }
433 
434  constexpr size_type
435  find_last_not_of(basic_string_view __str,
436  size_type __pos = npos) const noexcept
437  { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
438 
439  constexpr size_type
440  find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
441 
442  constexpr size_type
443  find_last_not_of(const _CharT* __str,
444  size_type __pos, size_type __n) const noexcept;
445 
446  __attribute__((__nonnull__)) constexpr size_type
447  find_last_not_of(const _CharT* __str,
448  size_type __pos = npos) const noexcept
449  {
450  return this->find_last_not_of(__str, __pos,
451  traits_type::length(__str));
452  }
453 
454  private:
455 
456  static constexpr int
457  _S_compare(size_type __n1, size_type __n2) noexcept
458  {
459  const difference_type __diff = __n1 - __n2;
460  if (__diff > __detail::__int_limits<int>::max())
461  return __detail::__int_limits<int>::max();
462  if (__diff < __detail::__int_limits<int>::min())
463  return __detail::__int_limits<int>::min();
464  return static_cast<int>(__diff);
465  }
466 
467  size_t _M_len;
468  const _CharT* _M_str;
469  };
470 
471 #if __cplusplus > 201703L && __cpp_lib_concepts && __cpp_deduction_guides
472  template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
473  basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
474 #endif
475 
476  // [string.view.comparison], non-member basic_string_view comparison function
477 
478  // Several of these functions use type_identity_t to create a non-deduced
479  // context, so that only one argument participates in template argument
480  // deduction and the other argument gets implicitly converted to the deduced
481  // type (see N3766).
482 
483  template<typename _CharT, typename _Traits>
484  constexpr bool
485  operator==(basic_string_view<_CharT, _Traits> __x,
486  basic_string_view<_CharT, _Traits> __y) noexcept
487  { return __x.size() == __y.size() && __x.compare(__y) == 0; }
488 
489  template<typename _CharT, typename _Traits>
490  constexpr bool
491  operator==(basic_string_view<_CharT, _Traits> __x,
492  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
493  noexcept
494  { return __x.size() == __y.size() && __x.compare(__y) == 0; }
495 
496  template<typename _CharT, typename _Traits>
497  constexpr bool
498  operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
499  basic_string_view<_CharT, _Traits> __y) noexcept
500  { return __x.size() == __y.size() && __x.compare(__y) == 0; }
501 
502  template<typename _CharT, typename _Traits>
503  constexpr bool
504  operator!=(basic_string_view<_CharT, _Traits> __x,
505  basic_string_view<_CharT, _Traits> __y) noexcept
506  { return !(__x == __y); }
507 
508  template<typename _CharT, typename _Traits>
509  constexpr bool
510  operator!=(basic_string_view<_CharT, _Traits> __x,
511  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
512  noexcept
513  { return !(__x == __y); }
514 
515  template<typename _CharT, typename _Traits>
516  constexpr bool
517  operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
518  basic_string_view<_CharT, _Traits> __y) noexcept
519  { return !(__x == __y); }
520 
521  template<typename _CharT, typename _Traits>
522  constexpr bool
523  operator< (basic_string_view<_CharT, _Traits> __x,
524  basic_string_view<_CharT, _Traits> __y) noexcept
525  { return __x.compare(__y) < 0; }
526 
527  template<typename _CharT, typename _Traits>
528  constexpr bool
529  operator< (basic_string_view<_CharT, _Traits> __x,
530  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
531  noexcept
532  { return __x.compare(__y) < 0; }
533 
534  template<typename _CharT, typename _Traits>
535  constexpr bool
536  operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
537  basic_string_view<_CharT, _Traits> __y) noexcept
538  { return __x.compare(__y) < 0; }
539 
540  template<typename _CharT, typename _Traits>
541  constexpr bool
542  operator> (basic_string_view<_CharT, _Traits> __x,
543  basic_string_view<_CharT, _Traits> __y) noexcept
544  { return __x.compare(__y) > 0; }
545 
546  template<typename _CharT, typename _Traits>
547  constexpr bool
548  operator> (basic_string_view<_CharT, _Traits> __x,
549  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
550  noexcept
551  { return __x.compare(__y) > 0; }
552 
553  template<typename _CharT, typename _Traits>
554  constexpr bool
555  operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
556  basic_string_view<_CharT, _Traits> __y) noexcept
557  { return __x.compare(__y) > 0; }
558 
559  template<typename _CharT, typename _Traits>
560  constexpr bool
561  operator<=(basic_string_view<_CharT, _Traits> __x,
562  basic_string_view<_CharT, _Traits> __y) noexcept
563  { return __x.compare(__y) <= 0; }
564 
565  template<typename _CharT, typename _Traits>
566  constexpr bool
567  operator<=(basic_string_view<_CharT, _Traits> __x,
568  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
569  noexcept
570  { return __x.compare(__y) <= 0; }
571 
572  template<typename _CharT, typename _Traits>
573  constexpr bool
574  operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
575  basic_string_view<_CharT, _Traits> __y) noexcept
576  { return __x.compare(__y) <= 0; }
577 
578  template<typename _CharT, typename _Traits>
579  constexpr bool
580  operator>=(basic_string_view<_CharT, _Traits> __x,
581  basic_string_view<_CharT, _Traits> __y) noexcept
582  { return __x.compare(__y) >= 0; }
583 
584  template<typename _CharT, typename _Traits>
585  constexpr bool
586  operator>=(basic_string_view<_CharT, _Traits> __x,
587  __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
588  noexcept
589  { return __x.compare(__y) >= 0; }
590 
591  template<typename _CharT, typename _Traits>
592  constexpr bool
593  operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
594  basic_string_view<_CharT, _Traits> __y) noexcept
595  { return __x.compare(__y) >= 0; }
596 
597  // [string.view.io], Inserters and extractors
598  template<typename _CharT, typename _Traits>
599  inline basic_ostream<_CharT, _Traits>&
600  operator<<(basic_ostream<_CharT, _Traits>& __os,
601  basic_string_view<_CharT,_Traits> __str)
602  { return __ostream_insert(__os, __str.data(), __str.size()); }
603 
604 
605  // basic_string_view typedef names
606 
607  using string_view = basic_string_view<char>;
608 #ifdef _GLIBCXX_USE_WCHAR_T
609  using wstring_view = basic_string_view<wchar_t>;
610 #endif
611 #ifdef _GLIBCXX_USE_CHAR8_T
612  using u8string_view = basic_string_view<char8_t>;
613 #endif
614  using u16string_view = basic_string_view<char16_t>;
615  using u32string_view = basic_string_view<char32_t>;
616 
617  // [string.view.hash], hash support:
618 
619  template<typename _Tp>
620  struct hash;
621 
622  template<>
623  struct hash<string_view>
624  : public __hash_base<size_t, string_view>
625  {
626  size_t
627  operator()(const string_view& __str) const noexcept
628  { return std::_Hash_impl::hash(__str.data(), __str.length()); }
629  };
630 
631  template<>
632  struct __is_fast_hash<hash<string_view>> : std::false_type
633  { };
634 
635 #ifdef _GLIBCXX_USE_WCHAR_T
636  template<>
637  struct hash<wstring_view>
638  : public __hash_base<size_t, wstring_view>
639  {
640  size_t
641  operator()(const wstring_view& __s) const noexcept
642  { return std::_Hash_impl::hash(__s.data(),
643  __s.length() * sizeof(wchar_t)); }
644  };
645 
646  template<>
647  struct __is_fast_hash<hash<wstring_view>> : std::false_type
648  { };
649 #endif
650 
651 #ifdef _GLIBCXX_USE_CHAR8_T
652  template<>
653  struct hash<u8string_view>
654  : public __hash_base<size_t, u8string_view>
655  {
656  size_t
657  operator()(const u8string_view& __str) const noexcept
658  { return std::_Hash_impl::hash(__str.data(), __str.length()); }
659  };
660 
661  template<>
662  struct __is_fast_hash<hash<u8string_view>> : std::false_type
663  { };
664 #endif
665 
666  template<>
667  struct hash<u16string_view>
668  : public __hash_base<size_t, u16string_view>
669  {
670  size_t
671  operator()(const u16string_view& __s) const noexcept
672  { return std::_Hash_impl::hash(__s.data(),
673  __s.length() * sizeof(char16_t)); }
674  };
675 
676  template<>
677  struct __is_fast_hash<hash<u16string_view>> : std::false_type
678  { };
679 
680  template<>
681  struct hash<u32string_view>
682  : public __hash_base<size_t, u32string_view>
683  {
684  size_t
685  operator()(const u32string_view& __s) const noexcept
686  { return std::_Hash_impl::hash(__s.data(),
687  __s.length() * sizeof(char32_t)); }
688  };
689 
690  template<>
691  struct __is_fast_hash<hash<u32string_view>> : std::false_type
692  { };
693 
694  inline namespace literals
695  {
696  inline namespace string_view_literals
697  {
698 #pragma GCC diagnostic push
699 #pragma GCC diagnostic ignored "-Wliteral-suffix"
700  inline constexpr basic_string_view<char>
701  operator""sv(const char* __str, size_t __len) noexcept
702  { return basic_string_view<char>{__str, __len}; }
703 
704 #ifdef _GLIBCXX_USE_WCHAR_T
705  inline constexpr basic_string_view<wchar_t>
706  operator""sv(const wchar_t* __str, size_t __len) noexcept
707  { return basic_string_view<wchar_t>{__str, __len}; }
708 #endif
709 
710 #ifdef _GLIBCXX_USE_CHAR8_T
711  inline constexpr basic_string_view<char8_t>
712  operator""sv(const char8_t* __str, size_t __len) noexcept
713  { return basic_string_view<char8_t>{__str, __len}; }
714 #endif
715 
716  inline constexpr basic_string_view<char16_t>
717  operator""sv(const char16_t* __str, size_t __len) noexcept
718  { return basic_string_view<char16_t>{__str, __len}; }
719 
720  inline constexpr basic_string_view<char32_t>
721  operator""sv(const char32_t* __str, size_t __len) noexcept
722  { return basic_string_view<char32_t>{__str, __len}; }
723 
724 #pragma GCC diagnostic pop
725  } // namespace string_literals
726  } // namespace literals
727 
728 #if __cpp_lib_concepts
729  namespace ranges
730  {
731  // Opt-in to borrowed_range concept
732  template<typename _CharT, typename _Traits>
733  inline constexpr bool
734  enable_borrowed_range<basic_string_view<_CharT, _Traits>> = true;
735 
736  // Opt-in to view concept
737  template<typename _CharT, typename _Traits>
738  inline constexpr bool
739  enable_view<basic_string_view<_CharT, _Traits>> = true;
740  }
741 #endif
742 _GLIBCXX_END_NAMESPACE_VERSION
743 } // namespace std
744 
745 #include <bits/string_view.tcc>
746 
747 #endif // __cplusplus <= 201402L
748 
749 #endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW