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 noexcept(noexcept(__last - __first))
148 : _M_len(__last - __first), _M_str(std::to_address(__first))
151 #if __cplusplus > 202002L
152 template<typename _Range, typename _DRange = remove_cvref_t<_Range>>
153 requires (!is_same_v<_DRange, basic_string_view>)
154 && ranges::contiguous_range<_Range>
155 && ranges::sized_range<_Range>
156 && is_same_v<ranges::range_value_t<_Range>, _CharT>
157 && (!is_convertible_v<_Range, const _CharT*>)
158 && (!requires (_DRange& __d) {
159 __d.operator ::std::basic_string_view<_CharT, _Traits>();
161 && (!requires { typename _DRange::traits_type; }
162 || is_same_v<typename _DRange::traits_type, _Traits>)
164 basic_string_view(_Range&& __r)
165 noexcept(noexcept(ranges::size(__r)) && noexcept(ranges::data(__r)))
166 : _M_len(ranges::size(__r)), _M_str(ranges::data(__r))
171 constexpr basic_string_view&
172 operator=(const basic_string_view&) noexcept = default;
174 // [string.view.iterators], iterator support
176 constexpr const_iterator
177 begin() const noexcept
178 { return this->_M_str; }
180 constexpr const_iterator
182 { return this->_M_str + this->_M_len; }
184 constexpr const_iterator
185 cbegin() const noexcept
186 { return this->_M_str; }
188 constexpr const_iterator
189 cend() const noexcept
190 { return this->_M_str + this->_M_len; }
192 constexpr const_reverse_iterator
193 rbegin() const noexcept
194 { return const_reverse_iterator(this->end()); }
196 constexpr const_reverse_iterator
197 rend() const noexcept
198 { return const_reverse_iterator(this->begin()); }
200 constexpr const_reverse_iterator
201 crbegin() const noexcept
202 { return const_reverse_iterator(this->end()); }
204 constexpr const_reverse_iterator
205 crend() const noexcept
206 { return const_reverse_iterator(this->begin()); }
208 // [string.view.capacity], capacity
211 size() const noexcept
212 { return this->_M_len; }
215 length() const noexcept
219 max_size() const noexcept
221 return (npos - sizeof(size_type) - sizeof(void*))
222 / sizeof(value_type) / 4;
225 [[nodiscard]] constexpr bool
226 empty() const noexcept
227 { return this->_M_len == 0; }
229 // [string.view.access], element access
231 constexpr const_reference
232 operator[](size_type __pos) const noexcept
234 __glibcxx_assert(__pos < this->_M_len);
235 return *(this->_M_str + __pos);
238 constexpr const_reference
239 at(size_type __pos) const
242 __throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
243 "(which is %zu) >= this->size() "
244 "(which is %zu)"), __pos, this->size());
245 return *(this->_M_str + __pos);
248 constexpr const_reference
249 front() const noexcept
251 __glibcxx_assert(this->_M_len > 0);
252 return *this->_M_str;
255 constexpr const_reference
256 back() const noexcept
258 __glibcxx_assert(this->_M_len > 0);
259 return *(this->_M_str + this->_M_len - 1);
262 constexpr const_pointer
263 data() const noexcept
264 { return this->_M_str; }
266 // [string.view.modifiers], modifiers:
269 remove_prefix(size_type __n) noexcept
271 __glibcxx_assert(this->_M_len >= __n);
277 remove_suffix(size_type __n) noexcept
279 __glibcxx_assert(this->_M_len >= __n);
284 swap(basic_string_view& __sv) noexcept
291 // [string.view.ops], string operations:
295 copy(_CharT* __str, size_type __n, size_type __pos = 0) const
297 __glibcxx_requires_string_len(__str, __n);
298 __pos = std::__sv_check(size(), __pos, "basic_string_view::copy");
299 const size_type __rlen = std::min(__n, _M_len - __pos);
300 // _GLIBCXX_RESOLVE_LIB_DEFECTS
301 // 2777. basic_string_view::copy should use char_traits::copy
302 traits_type::copy(__str, data() + __pos, __rlen);
306 constexpr basic_string_view
307 substr(size_type __pos = 0, size_type __n = npos) const noexcept(false)
309 __pos = std::__sv_check(size(), __pos, "basic_string_view::substr");
310 const size_type __rlen = std::min(__n, _M_len - __pos);
311 return basic_string_view{_M_str + __pos, __rlen};
315 compare(basic_string_view __str) const noexcept
317 const size_type __rlen = std::min(this->_M_len, __str._M_len);
318 int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen);
320 __ret = _S_compare(this->_M_len, __str._M_len);
325 compare(size_type __pos1, size_type __n1, basic_string_view __str) const
326 { return this->substr(__pos1, __n1).compare(__str); }
329 compare(size_type __pos1, size_type __n1,
330 basic_string_view __str, size_type __pos2, size_type __n2) const
332 return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
335 __attribute__((__nonnull__)) constexpr int
336 compare(const _CharT* __str) const noexcept
337 { return this->compare(basic_string_view{__str}); }
339 __attribute__((__nonnull__)) constexpr int
340 compare(size_type __pos1, size_type __n1, const _CharT* __str) const
341 { return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
344 compare(size_type __pos1, size_type __n1,
345 const _CharT* __str, size_type __n2) const noexcept(false)
347 return this->substr(__pos1, __n1)
348 .compare(basic_string_view(__str, __n2));
351 #if __cplusplus > 201703L
352 #define __cpp_lib_starts_ends_with 201711L
354 starts_with(basic_string_view __x) const noexcept
355 { return this->substr(0, __x.size()) == __x; }
358 starts_with(_CharT __x) const noexcept
359 { return !this->empty() && traits_type::eq(this->front(), __x); }
362 starts_with(const _CharT* __x) const noexcept
363 { return this->starts_with(basic_string_view(__x)); }
366 ends_with(basic_string_view __x) const noexcept
368 const auto __len = this->size();
369 const auto __xlen = __x.size();
370 return __len >= __xlen
371 && traits_type::compare(end() - __xlen, __x.data(), __xlen) == 0;
375 ends_with(_CharT __x) const noexcept
376 { return !this->empty() && traits_type::eq(this->back(), __x); }
379 ends_with(const _CharT* __x) const noexcept
380 { return this->ends_with(basic_string_view(__x)); }
383 #if __cplusplus > 202002L
384 #define __cpp_lib_string_contains 202011L
386 contains(basic_string_view __x) const noexcept
387 { return this->find(__x) != npos; }
390 contains(_CharT __x) const noexcept
391 { return this->find(__x) != npos; }
394 contains(const _CharT* __x) const noexcept
395 { return this->find(__x) != npos; }
398 // [string.view.find], searching
401 find(basic_string_view __str, size_type __pos = 0) const noexcept
402 { return this->find(__str._M_str, __pos, __str._M_len); }
405 find(_CharT __c, size_type __pos = 0) const noexcept;
408 find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
410 __attribute__((__nonnull__)) constexpr size_type
411 find(const _CharT* __str, size_type __pos = 0) const noexcept
412 { return this->find(__str, __pos, traits_type::length(__str)); }
415 rfind(basic_string_view __str, size_type __pos = npos) const noexcept
416 { return this->rfind(__str._M_str, __pos, __str._M_len); }
419 rfind(_CharT __c, size_type __pos = npos) const noexcept;
422 rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
424 __attribute__((__nonnull__)) constexpr size_type
425 rfind(const _CharT* __str, size_type __pos = npos) const noexcept
426 { return this->rfind(__str, __pos, traits_type::length(__str)); }
429 find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
430 { return this->find_first_of(__str._M_str, __pos, __str._M_len); }
433 find_first_of(_CharT __c, size_type __pos = 0) const noexcept
434 { return this->find(__c, __pos); }
437 find_first_of(const _CharT* __str, size_type __pos,
438 size_type __n) const noexcept;
440 __attribute__((__nonnull__)) constexpr size_type
441 find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
442 { return this->find_first_of(__str, __pos, traits_type::length(__str)); }
445 find_last_of(basic_string_view __str,
446 size_type __pos = npos) const noexcept
447 { return this->find_last_of(__str._M_str, __pos, __str._M_len); }
450 find_last_of(_CharT __c, size_type __pos=npos) const noexcept
451 { return this->rfind(__c, __pos); }
454 find_last_of(const _CharT* __str, size_type __pos,
455 size_type __n) const noexcept;
457 __attribute__((__nonnull__)) constexpr size_type
458 find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
459 { return this->find_last_of(__str, __pos, traits_type::length(__str)); }
462 find_first_not_of(basic_string_view __str,
463 size_type __pos = 0) const noexcept
464 { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
467 find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
470 find_first_not_of(const _CharT* __str,
471 size_type __pos, size_type __n) const noexcept;
473 __attribute__((__nonnull__)) constexpr size_type
474 find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
476 return this->find_first_not_of(__str, __pos,
477 traits_type::length(__str));
481 find_last_not_of(basic_string_view __str,
482 size_type __pos = npos) const noexcept
483 { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
486 find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
489 find_last_not_of(const _CharT* __str,
490 size_type __pos, size_type __n) const noexcept;
492 __attribute__((__nonnull__)) constexpr size_type
493 find_last_not_of(const _CharT* __str,
494 size_type __pos = npos) const noexcept
496 return this->find_last_not_of(__str, __pos,
497 traits_type::length(__str));
503 _S_compare(size_type __n1, size_type __n2) noexcept
505 using __limits = __gnu_cxx::__int_traits<int>;
506 const difference_type __diff = __n1 - __n2;
507 if (__diff > __limits::__max)
508 return __limits::__max;
509 if (__diff < __limits::__min)
510 return __limits::__min;
511 return static_cast<int>(__diff);
515 const _CharT* _M_str;
518 #if __cplusplus > 201703L && __cpp_lib_concepts && __cpp_deduction_guides
519 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
520 basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
522 #if __cplusplus > 202002L
523 template<ranges::contiguous_range _Range>
524 basic_string_view(_Range&&)
525 -> basic_string_view<ranges::range_value_t<_Range>>;
529 // [string.view.comparison], non-member basic_string_view comparison function
531 // Several of these functions use type_identity_t to create a non-deduced
532 // context, so that only one argument participates in template argument
533 // deduction and the other argument gets implicitly converted to the deduced
536 template<typename _CharT, typename _Traits>
538 operator==(basic_string_view<_CharT, _Traits> __x,
539 basic_string_view<_CharT, _Traits> __y) noexcept
540 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
542 template<typename _CharT, typename _Traits>
544 operator==(basic_string_view<_CharT, _Traits> __x,
545 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
547 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
549 #if __cpp_lib_three_way_comparison
550 template<typename _CharT, typename _Traits>
552 operator<=>(basic_string_view<_CharT, _Traits> __x,
553 basic_string_view<_CharT, _Traits> __y) noexcept
554 -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
555 { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
557 template<typename _CharT, typename _Traits>
559 operator<=>(basic_string_view<_CharT, _Traits> __x,
560 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
562 -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
563 { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
565 template<typename _CharT, typename _Traits>
567 operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
568 basic_string_view<_CharT, _Traits> __y) noexcept
569 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
571 template<typename _CharT, typename _Traits>
573 operator!=(basic_string_view<_CharT, _Traits> __x,
574 basic_string_view<_CharT, _Traits> __y) noexcept
575 { return !(__x == __y); }
577 template<typename _CharT, typename _Traits>
579 operator!=(basic_string_view<_CharT, _Traits> __x,
580 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
582 { return !(__x == __y); }
584 template<typename _CharT, typename _Traits>
586 operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
587 basic_string_view<_CharT, _Traits> __y) noexcept
588 { return !(__x == __y); }
590 template<typename _CharT, typename _Traits>
592 operator< (basic_string_view<_CharT, _Traits> __x,
593 basic_string_view<_CharT, _Traits> __y) noexcept
594 { return __x.compare(__y) < 0; }
596 template<typename _CharT, typename _Traits>
598 operator< (basic_string_view<_CharT, _Traits> __x,
599 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
601 { return __x.compare(__y) < 0; }
603 template<typename _CharT, typename _Traits>
605 operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
606 basic_string_view<_CharT, _Traits> __y) noexcept
607 { return __x.compare(__y) < 0; }
609 template<typename _CharT, typename _Traits>
611 operator> (basic_string_view<_CharT, _Traits> __x,
612 basic_string_view<_CharT, _Traits> __y) noexcept
613 { return __x.compare(__y) > 0; }
615 template<typename _CharT, typename _Traits>
617 operator> (basic_string_view<_CharT, _Traits> __x,
618 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
620 { return __x.compare(__y) > 0; }
622 template<typename _CharT, typename _Traits>
624 operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
625 basic_string_view<_CharT, _Traits> __y) noexcept
626 { return __x.compare(__y) > 0; }
628 template<typename _CharT, typename _Traits>
630 operator<=(basic_string_view<_CharT, _Traits> __x,
631 basic_string_view<_CharT, _Traits> __y) noexcept
632 { return __x.compare(__y) <= 0; }
634 template<typename _CharT, typename _Traits>
636 operator<=(basic_string_view<_CharT, _Traits> __x,
637 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
639 { return __x.compare(__y) <= 0; }
641 template<typename _CharT, typename _Traits>
643 operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
644 basic_string_view<_CharT, _Traits> __y) noexcept
645 { return __x.compare(__y) <= 0; }
647 template<typename _CharT, typename _Traits>
649 operator>=(basic_string_view<_CharT, _Traits> __x,
650 basic_string_view<_CharT, _Traits> __y) noexcept
651 { return __x.compare(__y) >= 0; }
653 template<typename _CharT, typename _Traits>
655 operator>=(basic_string_view<_CharT, _Traits> __x,
656 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
658 { return __x.compare(__y) >= 0; }
660 template<typename _CharT, typename _Traits>
662 operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
663 basic_string_view<_CharT, _Traits> __y) noexcept
664 { return __x.compare(__y) >= 0; }
665 #endif // three-way comparison
667 // [string.view.io], Inserters and extractors
668 template<typename _CharT, typename _Traits>
669 inline basic_ostream<_CharT, _Traits>&
670 operator<<(basic_ostream<_CharT, _Traits>& __os,
671 basic_string_view<_CharT,_Traits> __str)
672 { return __ostream_insert(__os, __str.data(), __str.size()); }
675 // basic_string_view typedef names
677 using string_view = basic_string_view<char>;
678 #ifdef _GLIBCXX_USE_WCHAR_T
679 using wstring_view = basic_string_view<wchar_t>;
681 #ifdef _GLIBCXX_USE_CHAR8_T
682 using u8string_view = basic_string_view<char8_t>;
684 using u16string_view = basic_string_view<char16_t>;
685 using u32string_view = basic_string_view<char32_t>;
687 // [string.view.hash], hash support:
689 template<typename _Tp>
693 struct hash<string_view>
694 : public __hash_base<size_t, string_view>
697 operator()(const string_view& __str) const noexcept
698 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
702 struct __is_fast_hash<hash<string_view>> : std::false_type
705 #ifdef _GLIBCXX_USE_WCHAR_T
707 struct hash<wstring_view>
708 : public __hash_base<size_t, wstring_view>
711 operator()(const wstring_view& __s) const noexcept
712 { return std::_Hash_impl::hash(__s.data(),
713 __s.length() * sizeof(wchar_t)); }
717 struct __is_fast_hash<hash<wstring_view>> : std::false_type
721 #ifdef _GLIBCXX_USE_CHAR8_T
723 struct hash<u8string_view>
724 : public __hash_base<size_t, u8string_view>
727 operator()(const u8string_view& __str) const noexcept
728 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
732 struct __is_fast_hash<hash<u8string_view>> : std::false_type
737 struct hash<u16string_view>
738 : public __hash_base<size_t, u16string_view>
741 operator()(const u16string_view& __s) const noexcept
742 { return std::_Hash_impl::hash(__s.data(),
743 __s.length() * sizeof(char16_t)); }
747 struct __is_fast_hash<hash<u16string_view>> : std::false_type
751 struct hash<u32string_view>
752 : public __hash_base<size_t, u32string_view>
755 operator()(const u32string_view& __s) const noexcept
756 { return std::_Hash_impl::hash(__s.data(),
757 __s.length() * sizeof(char32_t)); }
761 struct __is_fast_hash<hash<u32string_view>> : std::false_type
764 inline namespace literals
766 inline namespace string_view_literals
768 #pragma GCC diagnostic push
769 #pragma GCC diagnostic ignored "-Wliteral-suffix"
770 inline constexpr basic_string_view<char>
771 operator""sv(const char* __str, size_t __len) noexcept
772 { return basic_string_view<char>{__str, __len}; }
774 #ifdef _GLIBCXX_USE_WCHAR_T
775 inline constexpr basic_string_view<wchar_t>
776 operator""sv(const wchar_t* __str, size_t __len) noexcept
777 { return basic_string_view<wchar_t>{__str, __len}; }
780 #ifdef _GLIBCXX_USE_CHAR8_T
781 inline constexpr basic_string_view<char8_t>
782 operator""sv(const char8_t* __str, size_t __len) noexcept
783 { return basic_string_view<char8_t>{__str, __len}; }
786 inline constexpr basic_string_view<char16_t>
787 operator""sv(const char16_t* __str, size_t __len) noexcept
788 { return basic_string_view<char16_t>{__str, __len}; }
790 inline constexpr basic_string_view<char32_t>
791 operator""sv(const char32_t* __str, size_t __len) noexcept
792 { return basic_string_view<char32_t>{__str, __len}; }
794 #pragma GCC diagnostic pop
795 } // namespace string_literals
796 } // namespace literals
798 #if __cpp_lib_concepts
801 // Opt-in to borrowed_range concept
802 template<typename _CharT, typename _Traits>
803 inline constexpr bool
804 enable_borrowed_range<basic_string_view<_CharT, _Traits>> = true;
806 // Opt-in to view concept
807 template<typename _CharT, typename _Traits>
808 inline constexpr bool
809 enable_view<basic_string_view<_CharT, _Traits>> = true;
812 _GLIBCXX_END_NAMESPACE_VERSION
815 #include <bits/string_view.tcc>
817 #endif // __cplusplus <= 201402L
819 #endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW