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