1 // Components for manipulating non-owning sequences of characters -*- C++ -*-
3 // Copyright (C) 2013-2024 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 #define __glibcxx_want_constexpr_char_traits
39 #define __glibcxx_want_constexpr_string_view
40 #define __glibcxx_want_freestanding_string_view
41 #define __glibcxx_want_string_view
42 #define __glibcxx_want_starts_ends_with
43 #define __glibcxx_want_string_contains
44 #include <bits/version.h>
46 #if __cplusplus >= 201703L
48 #include <bits/char_traits.h>
49 #include <bits/functexcept.h>
50 #include <bits/functional_hash.h>
51 #include <bits/range_access.h>
52 #include <bits/stl_algobase.h>
53 #include <ext/numeric_traits.h>
55 #if __cplusplus >= 202002L
56 # include <bits/ranges_base.h>
61 # include <bits/ostream_insert.h>
64 namespace std _GLIBCXX_VISIBILITY(default)
66 _GLIBCXX_BEGIN_NAMESPACE_VERSION
68 // Helper for basic_string and basic_string_view members.
70 __sv_check(size_t __size, size_t __pos, const char* __s)
73 __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > __size "
74 "(which is %zu)"), __s, __pos, __size);
78 // Helper for basic_string members.
79 // NB: __sv_limit doesn't check for a bad __pos value.
81 __sv_limit(size_t __size, size_t __pos, size_t __off) noexcept
83 const bool __testoff = __off < __size - __pos;
84 return __testoff ? __off : __size - __pos;
88 * @class basic_string_view <string_view>
89 * @brief A non-owning reference to a string.
94 * @tparam _CharT Type of character
95 * @tparam _Traits Traits for character type, defaults to
96 * char_traits<_CharT>.
98 * A basic_string_view looks like this:
105 template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
106 class basic_string_view
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>);
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);
129 // [string.view.cons], construction and assignment
132 basic_string_view() noexcept
133 : _M_len{0}, _M_str{nullptr}
136 constexpr basic_string_view(const basic_string_view&) noexcept = default;
138 [[__gnu__::__nonnull__]]
140 basic_string_view(const _CharT* __str) noexcept
141 : _M_len{traits_type::length(__str)},
146 basic_string_view(const _CharT* __str, size_type __len) noexcept
147 : _M_len{__len}, _M_str{__str}
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>)
155 basic_string_view(_It __first, _End __last)
156 noexcept(noexcept(__last - __first))
157 : _M_len(__last - __first), _M_str(std::to_address(__first))
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>();
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))
176 basic_string_view(nullptr_t) = delete;
180 constexpr basic_string_view&
181 operator=(const basic_string_view&) noexcept = default;
183 // [string.view.iterators], iterator support
186 constexpr const_iterator
187 begin() const noexcept
188 { return this->_M_str; }
191 constexpr const_iterator
193 { return this->_M_str + this->_M_len; }
196 constexpr const_iterator
197 cbegin() const noexcept
198 { return this->_M_str; }
201 constexpr const_iterator
202 cend() const noexcept
203 { return this->_M_str + this->_M_len; }
206 constexpr const_reverse_iterator
207 rbegin() const noexcept
208 { return const_reverse_iterator(this->end()); }
211 constexpr const_reverse_iterator
212 rend() const noexcept
213 { return const_reverse_iterator(this->begin()); }
216 constexpr const_reverse_iterator
217 crbegin() const noexcept
218 { return const_reverse_iterator(this->end()); }
221 constexpr const_reverse_iterator
222 crend() const noexcept
223 { return const_reverse_iterator(this->begin()); }
225 // [string.view.capacity], capacity
229 size() const noexcept
230 { return this->_M_len; }
234 length() const noexcept
239 max_size() const noexcept
241 return (npos - sizeof(size_type) - sizeof(void*))
242 / sizeof(value_type) / 4;
247 empty() const noexcept
248 { return this->_M_len == 0; }
250 // [string.view.access], element access
253 constexpr const_reference
254 operator[](size_type __pos) const noexcept
256 __glibcxx_assert(__pos < this->_M_len);
257 return *(this->_M_str + __pos);
261 constexpr const_reference
262 at(size_type __pos) const
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);
272 constexpr const_reference
273 front() const noexcept
275 __glibcxx_assert(this->_M_len > 0);
276 return *this->_M_str;
280 constexpr const_reference
281 back() const noexcept
283 __glibcxx_assert(this->_M_len > 0);
284 return *(this->_M_str + this->_M_len - 1);
288 constexpr const_pointer
289 data() const noexcept
290 { return this->_M_str; }
292 // [string.view.modifiers], modifiers:
295 remove_prefix(size_type __n) noexcept
297 __glibcxx_assert(this->_M_len >= __n);
303 remove_suffix(size_type __n) noexcept
305 __glibcxx_assert(this->_M_len >= __n);
310 swap(basic_string_view& __sv) noexcept
317 // [string.view.ops], string operations:
321 copy(_CharT* __str, size_type __n, size_type __pos = 0) const
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);
333 constexpr basic_string_view
334 substr(size_type __pos = 0, size_type __n = npos) const noexcept(false)
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};
343 compare(basic_string_view __str) const noexcept
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);
348 __ret = _S_compare(this->_M_len, __str._M_len);
354 compare(size_type __pos1, size_type __n1, basic_string_view __str) const
355 { return this->substr(__pos1, __n1).compare(__str); }
359 compare(size_type __pos1, size_type __n1,
360 basic_string_view __str, size_type __pos2, size_type __n2) const
362 return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
365 [[nodiscard, __gnu__::__nonnull__]]
367 compare(const _CharT* __str) const noexcept
368 { return this->compare(basic_string_view{__str}); }
370 [[nodiscard, __gnu__::__nonnull__]]
372 compare(size_type __pos1, size_type __n1, const _CharT* __str) const
373 { return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
377 compare(size_type __pos1, size_type __n1,
378 const _CharT* __str, size_type __n2) const noexcept(false)
380 return this->substr(__pos1, __n1)
381 .compare(basic_string_view(__str, __n2));
384 #ifdef __cpp_lib_starts_ends_with // C++ >= 20
387 starts_with(basic_string_view __x) const noexcept
389 return _M_len >= __x._M_len
390 && traits_type::compare(_M_str, __x._M_str, __x._M_len) == 0;
395 starts_with(_CharT __x) const noexcept
396 { return !this->empty() && traits_type::eq(this->front(), __x); }
398 [[nodiscard, __gnu__::__nonnull__]]
400 starts_with(const _CharT* __x) const noexcept
401 { return this->starts_with(basic_string_view(__x)); }
405 ends_with(basic_string_view __x) const noexcept
407 const auto __len = this->size();
408 const auto __xlen = __x.size();
409 return __len >= __xlen
410 && traits_type::compare(end() - __xlen, __x.data(), __xlen) == 0;
415 ends_with(_CharT __x) const noexcept
416 { return !this->empty() && traits_type::eq(this->back(), __x); }
418 [[nodiscard, __gnu__::__nonnull__]]
420 ends_with(const _CharT* __x) const noexcept
421 { return this->ends_with(basic_string_view(__x)); }
422 #endif // __cpp_lib_starts_ends_with
424 #if __cplusplus > 202002L
425 #if _GLIBCXX_HOSTED && !defined(__cpp_lib_string_contains)
426 // This FTM is not freestanding as it also implies matching <string>
427 // support, and <string> is omitted from the freestanding subset.
428 # error "libstdc++ bug: string_contains not defined when it should be"
432 contains(basic_string_view __x) const noexcept
433 { return this->find(__x) != npos; }
437 contains(_CharT __x) const noexcept
438 { return this->find(__x) != npos; }
440 [[nodiscard, __gnu__::__nonnull__]]
442 contains(const _CharT* __x) const noexcept
443 { return this->find(__x) != npos; }
446 // [string.view.find], searching
450 find(basic_string_view __str, size_type __pos = 0) const noexcept
451 { return this->find(__str._M_str, __pos, __str._M_len); }
455 find(_CharT __c, size_type __pos = 0) const noexcept;
459 find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
461 [[nodiscard, __gnu__::__nonnull__]]
463 find(const _CharT* __str, size_type __pos = 0) const noexcept
464 { return this->find(__str, __pos, traits_type::length(__str)); }
468 rfind(basic_string_view __str, size_type __pos = npos) const noexcept
469 { return this->rfind(__str._M_str, __pos, __str._M_len); }
473 rfind(_CharT __c, size_type __pos = npos) const noexcept;
477 rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
479 [[nodiscard, __gnu__::__nonnull__]]
481 rfind(const _CharT* __str, size_type __pos = npos) const noexcept
482 { return this->rfind(__str, __pos, traits_type::length(__str)); }
486 find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
487 { return this->find_first_of(__str._M_str, __pos, __str._M_len); }
491 find_first_of(_CharT __c, size_type __pos = 0) const noexcept
492 { return this->find(__c, __pos); }
496 find_first_of(const _CharT* __str, size_type __pos,
497 size_type __n) const noexcept;
499 [[nodiscard, __gnu__::__nonnull__]]
501 find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
502 { return this->find_first_of(__str, __pos, traits_type::length(__str)); }
506 find_last_of(basic_string_view __str,
507 size_type __pos = npos) const noexcept
508 { return this->find_last_of(__str._M_str, __pos, __str._M_len); }
512 find_last_of(_CharT __c, size_type __pos=npos) const noexcept
513 { return this->rfind(__c, __pos); }
517 find_last_of(const _CharT* __str, size_type __pos,
518 size_type __n) const noexcept;
520 [[nodiscard, __gnu__::__nonnull__]]
522 find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
523 { return this->find_last_of(__str, __pos, traits_type::length(__str)); }
527 find_first_not_of(basic_string_view __str,
528 size_type __pos = 0) const noexcept
529 { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
533 find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
537 find_first_not_of(const _CharT* __str,
538 size_type __pos, size_type __n) const noexcept;
540 [[nodiscard, __gnu__::__nonnull__]]
542 find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
544 return this->find_first_not_of(__str, __pos,
545 traits_type::length(__str));
550 find_last_not_of(basic_string_view __str,
551 size_type __pos = npos) const noexcept
552 { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
556 find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
560 find_last_not_of(const _CharT* __str,
561 size_type __pos, size_type __n) const noexcept;
563 [[nodiscard, __gnu__::__nonnull__]]
565 find_last_not_of(const _CharT* __str,
566 size_type __pos = npos) const noexcept
568 return this->find_last_not_of(__str, __pos,
569 traits_type::length(__str));
575 _S_compare(size_type __n1, size_type __n2) noexcept
577 using __limits = __gnu_cxx::__int_traits<int>;
578 const difference_type __diff = __n1 - __n2;
579 if (__diff > __limits::__max)
580 return __limits::__max;
581 if (__diff < __limits::__min)
582 return __limits::__min;
583 return static_cast<int>(__diff);
587 const _CharT* _M_str;
590 #if __cplusplus > 201703L && __cpp_lib_concepts && __cpp_deduction_guides
591 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
592 basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
594 #if __cplusplus > 202002L
595 template<ranges::contiguous_range _Range>
596 basic_string_view(_Range&&)
597 -> basic_string_view<ranges::range_value_t<_Range>>;
601 // [string.view.comparison], non-member basic_string_view comparison function
603 // Several of these functions use type_identity_t to create a non-deduced
604 // context, so that only one argument participates in template argument
605 // deduction and the other argument gets implicitly converted to the deduced
608 #if __cpp_lib_three_way_comparison
609 template<typename _CharT, typename _Traits>
612 operator==(basic_string_view<_CharT, _Traits> __x,
613 type_identity_t<basic_string_view<_CharT, _Traits>> __y)
615 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
617 template<typename _CharT, typename _Traits>
620 operator<=>(basic_string_view<_CharT, _Traits> __x,
621 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
623 -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
624 { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
626 template<typename _CharT, typename _Traits>
629 operator==(basic_string_view<_CharT, _Traits> __x,
630 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
632 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
634 template<typename _CharT, typename _Traits>
637 operator==(basic_string_view<_CharT, _Traits> __x,
638 basic_string_view<_CharT, _Traits> __y) noexcept
639 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
641 template<typename _CharT, typename _Traits>
644 operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
645 basic_string_view<_CharT, _Traits> __y) noexcept
646 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
648 template<typename _CharT, typename _Traits>
651 operator!=(basic_string_view<_CharT, _Traits> __x,
652 basic_string_view<_CharT, _Traits> __y) noexcept
653 { return !(__x == __y); }
655 template<typename _CharT, typename _Traits>
658 operator!=(basic_string_view<_CharT, _Traits> __x,
659 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
661 { return !(__x == __y); }
663 template<typename _CharT, typename _Traits>
666 operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
667 basic_string_view<_CharT, _Traits> __y) noexcept
668 { return !(__x == __y); }
670 template<typename _CharT, typename _Traits>
673 operator< (basic_string_view<_CharT, _Traits> __x,
674 basic_string_view<_CharT, _Traits> __y) noexcept
675 { return __x.compare(__y) < 0; }
677 template<typename _CharT, typename _Traits>
680 operator< (basic_string_view<_CharT, _Traits> __x,
681 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
683 { return __x.compare(__y) < 0; }
685 template<typename _CharT, typename _Traits>
688 operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
689 basic_string_view<_CharT, _Traits> __y) noexcept
690 { return __x.compare(__y) < 0; }
692 template<typename _CharT, typename _Traits>
695 operator> (basic_string_view<_CharT, _Traits> __x,
696 basic_string_view<_CharT, _Traits> __y) noexcept
697 { return __x.compare(__y) > 0; }
699 template<typename _CharT, typename _Traits>
702 operator> (basic_string_view<_CharT, _Traits> __x,
703 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
705 { return __x.compare(__y) > 0; }
707 template<typename _CharT, typename _Traits>
710 operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
711 basic_string_view<_CharT, _Traits> __y) noexcept
712 { return __x.compare(__y) > 0; }
714 template<typename _CharT, typename _Traits>
717 operator<=(basic_string_view<_CharT, _Traits> __x,
718 basic_string_view<_CharT, _Traits> __y) noexcept
719 { return __x.compare(__y) <= 0; }
721 template<typename _CharT, typename _Traits>
724 operator<=(basic_string_view<_CharT, _Traits> __x,
725 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
727 { return __x.compare(__y) <= 0; }
729 template<typename _CharT, typename _Traits>
732 operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
733 basic_string_view<_CharT, _Traits> __y) noexcept
734 { return __x.compare(__y) <= 0; }
736 template<typename _CharT, typename _Traits>
739 operator>=(basic_string_view<_CharT, _Traits> __x,
740 basic_string_view<_CharT, _Traits> __y) noexcept
741 { return __x.compare(__y) >= 0; }
743 template<typename _CharT, typename _Traits>
746 operator>=(basic_string_view<_CharT, _Traits> __x,
747 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
749 { return __x.compare(__y) >= 0; }
751 template<typename _CharT, typename _Traits>
754 operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
755 basic_string_view<_CharT, _Traits> __y) noexcept
756 { return __x.compare(__y) >= 0; }
757 #endif // three-way comparison
760 // [string.view.io], Inserters and extractors
761 template<typename _CharT, typename _Traits>
762 inline basic_ostream<_CharT, _Traits>&
763 operator<<(basic_ostream<_CharT, _Traits>& __os,
764 basic_string_view<_CharT,_Traits> __str)
765 { return __ostream_insert(__os, __str.data(), __str.size()); }
768 // basic_string_view typedef names
770 using string_view = basic_string_view<char>;
771 using wstring_view = basic_string_view<wchar_t>;
772 #ifdef _GLIBCXX_USE_CHAR8_T
773 using u8string_view = basic_string_view<char8_t>;
775 using u16string_view = basic_string_view<char16_t>;
776 using u32string_view = basic_string_view<char32_t>;
778 // [string.view.hash], hash support:
780 template<typename _Tp>
784 struct hash<string_view>
785 : public __hash_base<size_t, string_view>
789 operator()(const string_view& __str) const noexcept
790 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
794 struct __is_fast_hash<hash<string_view>> : std::false_type
798 struct hash<wstring_view>
799 : public __hash_base<size_t, wstring_view>
803 operator()(const wstring_view& __s) const noexcept
804 { return std::_Hash_impl::hash(__s.data(),
805 __s.length() * sizeof(wchar_t)); }
809 struct __is_fast_hash<hash<wstring_view>> : std::false_type
812 #ifdef _GLIBCXX_USE_CHAR8_T
814 struct hash<u8string_view>
815 : public __hash_base<size_t, u8string_view>
819 operator()(const u8string_view& __str) const noexcept
820 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
824 struct __is_fast_hash<hash<u8string_view>> : std::false_type
829 struct hash<u16string_view>
830 : public __hash_base<size_t, u16string_view>
834 operator()(const u16string_view& __s) const noexcept
835 { return std::_Hash_impl::hash(__s.data(),
836 __s.length() * sizeof(char16_t)); }
840 struct __is_fast_hash<hash<u16string_view>> : std::false_type
844 struct hash<u32string_view>
845 : public __hash_base<size_t, u32string_view>
849 operator()(const u32string_view& __s) const noexcept
850 { return std::_Hash_impl::hash(__s.data(),
851 __s.length() * sizeof(char32_t)); }
855 struct __is_fast_hash<hash<u32string_view>> : std::false_type
858 inline namespace literals
860 inline namespace string_view_literals
862 #pragma GCC diagnostic push
863 #pragma GCC diagnostic ignored "-Wliteral-suffix"
864 inline constexpr basic_string_view<char>
865 operator""sv(const char* __str, size_t __len) noexcept
866 { return basic_string_view<char>{__str, __len}; }
868 inline constexpr basic_string_view<wchar_t>
869 operator""sv(const wchar_t* __str, size_t __len) noexcept
870 { return basic_string_view<wchar_t>{__str, __len}; }
872 #ifdef _GLIBCXX_USE_CHAR8_T
873 inline constexpr basic_string_view<char8_t>
874 operator""sv(const char8_t* __str, size_t __len) noexcept
875 { return basic_string_view<char8_t>{__str, __len}; }
878 inline constexpr basic_string_view<char16_t>
879 operator""sv(const char16_t* __str, size_t __len) noexcept
880 { return basic_string_view<char16_t>{__str, __len}; }
882 inline constexpr basic_string_view<char32_t>
883 operator""sv(const char32_t* __str, size_t __len) noexcept
884 { return basic_string_view<char32_t>{__str, __len}; }
886 #pragma GCC diagnostic pop
887 } // namespace string_literals
888 } // namespace literals
890 #if __cpp_lib_concepts
893 // Opt-in to borrowed_range concept
894 template<typename _CharT, typename _Traits>
895 inline constexpr bool
896 enable_borrowed_range<basic_string_view<_CharT, _Traits>> = true;
898 // Opt-in to view concept
899 template<typename _CharT, typename _Traits>
900 inline constexpr bool
901 enable_view<basic_string_view<_CharT, _Traits>> = true;
904 _GLIBCXX_END_NAMESPACE_VERSION
907 #include <bits/string_view.tcc>
909 #endif // __cplusplus <= 201402L
911 #endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW