1 // Components for manipulating non-owning sequences of characters -*- C++ -*-
3 // Copyright (C) 2013-2021 Free Software Foundation, Inc.
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)
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.
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.
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/>.
25 /** @file include/string_view
26 * This is a Standard C++ Library header.
30 // N3762 basic_string_view library
33 #ifndef _GLIBCXX_STRING_VIEW
34 #define _GLIBCXX_STRING_VIEW 1
36 #pragma GCC system_header
38 #if __cplusplus >= 201703L
41 #include <bits/char_traits.h>
42 #include <bits/functional_hash.h>
43 #include <bits/range_access.h>
44 #include <bits/ostream_insert.h>
45 #include <ext/numeric_traits.h>
47 #if __cplusplus >= 202002L
48 # include <bits/ranges_base.h>
51 namespace std _GLIBCXX_VISIBILITY(default)
53 _GLIBCXX_BEGIN_NAMESPACE_VERSION
55 # define __cpp_lib_string_view 201803L
56 #if __cplusplus > 201703L
57 # define __cpp_lib_constexpr_string_view 201811L
60 // Helper for basic_string and basic_string_view members.
62 __sv_check(size_t __size, size_t __pos, const char* __s)
65 __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > __size "
66 "(which is %zu)"), __s, __pos, __size);
70 // Helper for basic_string members.
71 // NB: __sv_limit doesn't check for a bad __pos value.
73 __sv_limit(size_t __size, size_t __pos, size_t __off) noexcept
75 const bool __testoff = __off < __size - __pos;
76 return __testoff ? __off : __size - __pos;
80 * @class basic_string_view <string_view>
81 * @brief A non-owning reference to a string.
86 * @tparam _CharT Type of character
87 * @tparam _Traits Traits for character type, defaults to
88 * char_traits<_CharT>.
90 * A basic_string_view looks like this:
97 template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
98 class basic_string_view
100 static_assert(!is_array_v<_CharT>);
101 static_assert(is_trivial_v<_CharT> && is_standard_layout_v<_CharT>);
102 static_assert(is_same_v<_CharT, typename _Traits::char_type>);
107 using traits_type = _Traits;
108 using value_type = _CharT;
109 using pointer = value_type*;
110 using const_pointer = const value_type*;
111 using reference = value_type&;
112 using const_reference = const value_type&;
113 using const_iterator = const value_type*;
114 using iterator = const_iterator;
115 using const_reverse_iterator = std::reverse_iterator<const_iterator>;
116 using reverse_iterator = const_reverse_iterator;
117 using size_type = size_t;
118 using difference_type = ptrdiff_t;
119 static constexpr size_type npos = size_type(-1);
121 // [string.view.cons], construction and assignment
124 basic_string_view() noexcept
125 : _M_len{0}, _M_str{nullptr}
128 constexpr basic_string_view(const basic_string_view&) noexcept = default;
130 __attribute__((__nonnull__)) constexpr
131 basic_string_view(const _CharT* __str) noexcept
132 : _M_len{traits_type::length(__str)},
137 basic_string_view(const _CharT* __str, size_type __len) noexcept
138 : _M_len{__len}, _M_str{__str}
141 #if __cplusplus >= 202002L && __cpp_lib_concepts
142 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
143 requires same_as<iter_value_t<_It>, _CharT>
144 && (!convertible_to<_End, size_type>)
146 basic_string_view(_It __first, _End __last)
147 : _M_len(__last - __first), _M_str(std::to_address(__first))
150 #if __cplusplus > 202002L
151 template<typename _Range, typename _DRange = remove_cvref_t<_Range>>
152 requires (!is_same_v<_DRange, basic_string_view>)
153 && ranges::contiguous_range<_Range>
154 && ranges::sized_range<_Range>
155 && is_same_v<ranges::range_value_t<_Range>, _CharT>
156 && (!is_convertible_v<_Range, const _CharT*>)
157 && (!requires (_DRange& __d) {
158 __d.operator ::std::basic_string_view<_CharT, _Traits>();
160 && (!requires { typename _DRange::traits_type; }
161 || is_same_v<typename _DRange::traits_type, _Traits>)
163 basic_string_view(_Range&& __r)
164 noexcept(noexcept(ranges::size(__r)) && noexcept(ranges::data(__r)))
165 : _M_len(ranges::size(__r)), _M_str(ranges::data(__r))
170 constexpr basic_string_view&
171 operator=(const basic_string_view&) noexcept = default;
173 // [string.view.iterators], iterator support
175 constexpr const_iterator
176 begin() const noexcept
177 { return this->_M_str; }
179 constexpr const_iterator
181 { return this->_M_str + this->_M_len; }
183 constexpr const_iterator
184 cbegin() const noexcept
185 { return this->_M_str; }
187 constexpr const_iterator
188 cend() const noexcept
189 { return this->_M_str + this->_M_len; }
191 constexpr const_reverse_iterator
192 rbegin() const noexcept
193 { return const_reverse_iterator(this->end()); }
195 constexpr const_reverse_iterator
196 rend() const noexcept
197 { return const_reverse_iterator(this->begin()); }
199 constexpr const_reverse_iterator
200 crbegin() const noexcept
201 { return const_reverse_iterator(this->end()); }
203 constexpr const_reverse_iterator
204 crend() const noexcept
205 { return const_reverse_iterator(this->begin()); }
207 // [string.view.capacity], capacity
210 size() const noexcept
211 { return this->_M_len; }
214 length() const noexcept
218 max_size() const noexcept
220 return (npos - sizeof(size_type) - sizeof(void*))
221 / sizeof(value_type) / 4;
224 [[nodiscard]] constexpr bool
225 empty() const noexcept
226 { return this->_M_len == 0; }
228 // [string.view.access], element access
230 constexpr const_reference
231 operator[](size_type __pos) const noexcept
233 __glibcxx_assert(__pos < this->_M_len);
234 return *(this->_M_str + __pos);
237 constexpr const_reference
238 at(size_type __pos) const
241 __throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
242 "(which is %zu) >= this->size() "
243 "(which is %zu)"), __pos, this->size());
244 return *(this->_M_str + __pos);
247 constexpr const_reference
248 front() const noexcept
250 __glibcxx_assert(this->_M_len > 0);
251 return *this->_M_str;
254 constexpr const_reference
255 back() const noexcept
257 __glibcxx_assert(this->_M_len > 0);
258 return *(this->_M_str + this->_M_len - 1);
261 constexpr const_pointer
262 data() const noexcept
263 { return this->_M_str; }
265 // [string.view.modifiers], modifiers:
268 remove_prefix(size_type __n) noexcept
270 __glibcxx_assert(this->_M_len >= __n);
276 remove_suffix(size_type __n) noexcept
277 { this->_M_len -= __n; }
280 swap(basic_string_view& __sv) noexcept
287 // [string.view.ops], string operations:
291 copy(_CharT* __str, size_type __n, size_type __pos = 0) const
293 __glibcxx_requires_string_len(__str, __n);
294 __pos = std::__sv_check(size(), __pos, "basic_string_view::copy");
295 const size_type __rlen = std::min(__n, _M_len - __pos);
296 // _GLIBCXX_RESOLVE_LIB_DEFECTS
297 // 2777. basic_string_view::copy should use char_traits::copy
298 traits_type::copy(__str, data() + __pos, __rlen);
302 constexpr basic_string_view
303 substr(size_type __pos = 0, size_type __n = npos) const noexcept(false)
305 __pos = std::__sv_check(size(), __pos, "basic_string_view::substr");
306 const size_type __rlen = std::min(__n, _M_len - __pos);
307 return basic_string_view{_M_str + __pos, __rlen};
311 compare(basic_string_view __str) const noexcept
313 const size_type __rlen = std::min(this->_M_len, __str._M_len);
314 int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen);
316 __ret = _S_compare(this->_M_len, __str._M_len);
321 compare(size_type __pos1, size_type __n1, basic_string_view __str) const
322 { return this->substr(__pos1, __n1).compare(__str); }
325 compare(size_type __pos1, size_type __n1,
326 basic_string_view __str, size_type __pos2, size_type __n2) const
328 return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
331 __attribute__((__nonnull__)) constexpr int
332 compare(const _CharT* __str) const noexcept
333 { return this->compare(basic_string_view{__str}); }
335 __attribute__((__nonnull__)) constexpr int
336 compare(size_type __pos1, size_type __n1, const _CharT* __str) const
337 { return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
340 compare(size_type __pos1, size_type __n1,
341 const _CharT* __str, size_type __n2) const noexcept(false)
343 return this->substr(__pos1, __n1)
344 .compare(basic_string_view(__str, __n2));
347 #if __cplusplus > 201703L
348 #define __cpp_lib_starts_ends_with 201711L
350 starts_with(basic_string_view __x) const noexcept
351 { return this->substr(0, __x.size()) == __x; }
354 starts_with(_CharT __x) const noexcept
355 { return !this->empty() && traits_type::eq(this->front(), __x); }
358 starts_with(const _CharT* __x) const noexcept
359 { return this->starts_with(basic_string_view(__x)); }
362 ends_with(basic_string_view __x) const noexcept
364 const auto __len = this->size();
365 const auto __xlen = __x.size();
366 return __len >= __xlen
367 && traits_type::compare(end() - __xlen, __x.data(), __xlen) == 0;
371 ends_with(_CharT __x) const noexcept
372 { return !this->empty() && traits_type::eq(this->back(), __x); }
375 ends_with(const _CharT* __x) const noexcept
376 { return this->ends_with(basic_string_view(__x)); }
379 #if __cplusplus > 202002L
380 #define __cpp_lib_string_contains 202011L
382 contains(basic_string_view __x) const noexcept
383 { return this->find(__x) != npos; }
386 contains(_CharT __x) const noexcept
387 { return this->find(__x) != npos; }
390 contains(const _CharT* __x) const noexcept
391 { return this->find(__x) != npos; }
394 // [string.view.find], searching
397 find(basic_string_view __str, size_type __pos = 0) const noexcept
398 { return this->find(__str._M_str, __pos, __str._M_len); }
401 find(_CharT __c, size_type __pos = 0) const noexcept;
404 find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
406 __attribute__((__nonnull__)) constexpr size_type
407 find(const _CharT* __str, size_type __pos = 0) const noexcept
408 { return this->find(__str, __pos, traits_type::length(__str)); }
411 rfind(basic_string_view __str, size_type __pos = npos) const noexcept
412 { return this->rfind(__str._M_str, __pos, __str._M_len); }
415 rfind(_CharT __c, size_type __pos = npos) const noexcept;
418 rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
420 __attribute__((__nonnull__)) constexpr size_type
421 rfind(const _CharT* __str, size_type __pos = npos) const noexcept
422 { return this->rfind(__str, __pos, traits_type::length(__str)); }
425 find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
426 { return this->find_first_of(__str._M_str, __pos, __str._M_len); }
429 find_first_of(_CharT __c, size_type __pos = 0) const noexcept
430 { return this->find(__c, __pos); }
433 find_first_of(const _CharT* __str, size_type __pos,
434 size_type __n) const noexcept;
436 __attribute__((__nonnull__)) constexpr size_type
437 find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
438 { return this->find_first_of(__str, __pos, traits_type::length(__str)); }
441 find_last_of(basic_string_view __str,
442 size_type __pos = npos) const noexcept
443 { return this->find_last_of(__str._M_str, __pos, __str._M_len); }
446 find_last_of(_CharT __c, size_type __pos=npos) const noexcept
447 { return this->rfind(__c, __pos); }
450 find_last_of(const _CharT* __str, size_type __pos,
451 size_type __n) const noexcept;
453 __attribute__((__nonnull__)) constexpr size_type
454 find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
455 { return this->find_last_of(__str, __pos, traits_type::length(__str)); }
458 find_first_not_of(basic_string_view __str,
459 size_type __pos = 0) const noexcept
460 { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
463 find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
466 find_first_not_of(const _CharT* __str,
467 size_type __pos, size_type __n) const noexcept;
469 __attribute__((__nonnull__)) constexpr size_type
470 find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
472 return this->find_first_not_of(__str, __pos,
473 traits_type::length(__str));
477 find_last_not_of(basic_string_view __str,
478 size_type __pos = npos) const noexcept
479 { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
482 find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
485 find_last_not_of(const _CharT* __str,
486 size_type __pos, size_type __n) const noexcept;
488 __attribute__((__nonnull__)) constexpr size_type
489 find_last_not_of(const _CharT* __str,
490 size_type __pos = npos) const noexcept
492 return this->find_last_not_of(__str, __pos,
493 traits_type::length(__str));
499 _S_compare(size_type __n1, size_type __n2) noexcept
501 using __limits = __gnu_cxx::__int_traits<int>;
502 const difference_type __diff = __n1 - __n2;
503 if (__diff > __limits::__max)
504 return __limits::__max;
505 if (__diff < __limits::__min)
506 return __limits::__min;
507 return static_cast<int>(__diff);
511 const _CharT* _M_str;
514 #if __cplusplus > 201703L && __cpp_lib_concepts && __cpp_deduction_guides
515 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
516 basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
518 #if __cplusplus > 202002L
519 template<ranges::contiguous_range _Range>
520 basic_string_view(_Range&&)
521 -> basic_string_view<ranges::range_value_t<_Range>>;
525 // [string.view.comparison], non-member basic_string_view comparison function
527 // Several of these functions use type_identity_t to create a non-deduced
528 // context, so that only one argument participates in template argument
529 // deduction and the other argument gets implicitly converted to the deduced
532 template<typename _CharT, typename _Traits>
534 operator==(basic_string_view<_CharT, _Traits> __x,
535 basic_string_view<_CharT, _Traits> __y) noexcept
536 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
538 template<typename _CharT, typename _Traits>
540 operator==(basic_string_view<_CharT, _Traits> __x,
541 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
543 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
545 #if __cpp_lib_three_way_comparison
546 template<typename _CharT, typename _Traits>
548 operator<=>(basic_string_view<_CharT, _Traits> __x,
549 basic_string_view<_CharT, _Traits> __y) noexcept
550 -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
551 { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
553 template<typename _CharT, typename _Traits>
555 operator<=>(basic_string_view<_CharT, _Traits> __x,
556 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
558 -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
559 { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
561 template<typename _CharT, typename _Traits>
563 operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
564 basic_string_view<_CharT, _Traits> __y) noexcept
565 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
567 template<typename _CharT, typename _Traits>
569 operator!=(basic_string_view<_CharT, _Traits> __x,
570 basic_string_view<_CharT, _Traits> __y) noexcept
571 { return !(__x == __y); }
573 template<typename _CharT, typename _Traits>
575 operator!=(basic_string_view<_CharT, _Traits> __x,
576 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
578 { return !(__x == __y); }
580 template<typename _CharT, typename _Traits>
582 operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
583 basic_string_view<_CharT, _Traits> __y) noexcept
584 { return !(__x == __y); }
586 template<typename _CharT, typename _Traits>
588 operator< (basic_string_view<_CharT, _Traits> __x,
589 basic_string_view<_CharT, _Traits> __y) noexcept
590 { return __x.compare(__y) < 0; }
592 template<typename _CharT, typename _Traits>
594 operator< (basic_string_view<_CharT, _Traits> __x,
595 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
597 { return __x.compare(__y) < 0; }
599 template<typename _CharT, typename _Traits>
601 operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
602 basic_string_view<_CharT, _Traits> __y) noexcept
603 { return __x.compare(__y) < 0; }
605 template<typename _CharT, typename _Traits>
607 operator> (basic_string_view<_CharT, _Traits> __x,
608 basic_string_view<_CharT, _Traits> __y) noexcept
609 { return __x.compare(__y) > 0; }
611 template<typename _CharT, typename _Traits>
613 operator> (basic_string_view<_CharT, _Traits> __x,
614 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
616 { return __x.compare(__y) > 0; }
618 template<typename _CharT, typename _Traits>
620 operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
621 basic_string_view<_CharT, _Traits> __y) noexcept
622 { return __x.compare(__y) > 0; }
624 template<typename _CharT, typename _Traits>
626 operator<=(basic_string_view<_CharT, _Traits> __x,
627 basic_string_view<_CharT, _Traits> __y) noexcept
628 { return __x.compare(__y) <= 0; }
630 template<typename _CharT, typename _Traits>
632 operator<=(basic_string_view<_CharT, _Traits> __x,
633 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
635 { return __x.compare(__y) <= 0; }
637 template<typename _CharT, typename _Traits>
639 operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
640 basic_string_view<_CharT, _Traits> __y) noexcept
641 { return __x.compare(__y) <= 0; }
643 template<typename _CharT, typename _Traits>
645 operator>=(basic_string_view<_CharT, _Traits> __x,
646 basic_string_view<_CharT, _Traits> __y) noexcept
647 { return __x.compare(__y) >= 0; }
649 template<typename _CharT, typename _Traits>
651 operator>=(basic_string_view<_CharT, _Traits> __x,
652 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
654 { return __x.compare(__y) >= 0; }
656 template<typename _CharT, typename _Traits>
658 operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
659 basic_string_view<_CharT, _Traits> __y) noexcept
660 { return __x.compare(__y) >= 0; }
661 #endif // three-way comparison
663 // [string.view.io], Inserters and extractors
664 template<typename _CharT, typename _Traits>
665 inline basic_ostream<_CharT, _Traits>&
666 operator<<(basic_ostream<_CharT, _Traits>& __os,
667 basic_string_view<_CharT,_Traits> __str)
668 { return __ostream_insert(__os, __str.data(), __str.size()); }
671 // basic_string_view typedef names
673 using string_view = basic_string_view<char>;
674 #ifdef _GLIBCXX_USE_WCHAR_T
675 using wstring_view = basic_string_view<wchar_t>;
677 #ifdef _GLIBCXX_USE_CHAR8_T
678 using u8string_view = basic_string_view<char8_t>;
680 using u16string_view = basic_string_view<char16_t>;
681 using u32string_view = basic_string_view<char32_t>;
683 // [string.view.hash], hash support:
685 template<typename _Tp>
689 struct hash<string_view>
690 : public __hash_base<size_t, string_view>
693 operator()(const string_view& __str) const noexcept
694 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
698 struct __is_fast_hash<hash<string_view>> : std::false_type
701 #ifdef _GLIBCXX_USE_WCHAR_T
703 struct hash<wstring_view>
704 : public __hash_base<size_t, wstring_view>
707 operator()(const wstring_view& __s) const noexcept
708 { return std::_Hash_impl::hash(__s.data(),
709 __s.length() * sizeof(wchar_t)); }
713 struct __is_fast_hash<hash<wstring_view>> : std::false_type
717 #ifdef _GLIBCXX_USE_CHAR8_T
719 struct hash<u8string_view>
720 : public __hash_base<size_t, u8string_view>
723 operator()(const u8string_view& __str) const noexcept
724 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
728 struct __is_fast_hash<hash<u8string_view>> : std::false_type
733 struct hash<u16string_view>
734 : public __hash_base<size_t, u16string_view>
737 operator()(const u16string_view& __s) const noexcept
738 { return std::_Hash_impl::hash(__s.data(),
739 __s.length() * sizeof(char16_t)); }
743 struct __is_fast_hash<hash<u16string_view>> : std::false_type
747 struct hash<u32string_view>
748 : public __hash_base<size_t, u32string_view>
751 operator()(const u32string_view& __s) const noexcept
752 { return std::_Hash_impl::hash(__s.data(),
753 __s.length() * sizeof(char32_t)); }
757 struct __is_fast_hash<hash<u32string_view>> : std::false_type
760 inline namespace literals
762 inline namespace string_view_literals
764 #pragma GCC diagnostic push
765 #pragma GCC diagnostic ignored "-Wliteral-suffix"
766 inline constexpr basic_string_view<char>
767 operator""sv(const char* __str, size_t __len) noexcept
768 { return basic_string_view<char>{__str, __len}; }
770 #ifdef _GLIBCXX_USE_WCHAR_T
771 inline constexpr basic_string_view<wchar_t>
772 operator""sv(const wchar_t* __str, size_t __len) noexcept
773 { return basic_string_view<wchar_t>{__str, __len}; }
776 #ifdef _GLIBCXX_USE_CHAR8_T
777 inline constexpr basic_string_view<char8_t>
778 operator""sv(const char8_t* __str, size_t __len) noexcept
779 { return basic_string_view<char8_t>{__str, __len}; }
782 inline constexpr basic_string_view<char16_t>
783 operator""sv(const char16_t* __str, size_t __len) noexcept
784 { return basic_string_view<char16_t>{__str, __len}; }
786 inline constexpr basic_string_view<char32_t>
787 operator""sv(const char32_t* __str, size_t __len) noexcept
788 { return basic_string_view<char32_t>{__str, __len}; }
790 #pragma GCC diagnostic pop
791 } // namespace string_literals
792 } // namespace literals
794 #if __cpp_lib_concepts
797 // Opt-in to borrowed_range concept
798 template<typename _CharT, typename _Traits>
799 inline constexpr bool
800 enable_borrowed_range<basic_string_view<_CharT, _Traits>> = true;
802 // Opt-in to view concept
803 template<typename _CharT, typename _Traits>
804 inline constexpr bool
805 enable_view<basic_string_view<_CharT, _Traits>> = true;
808 _GLIBCXX_END_NAMESPACE_VERSION
811 #include <bits/string_view.tcc>
813 #endif // __cplusplus <= 201402L
815 #endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW