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1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_STRING_VIEW
11#define _LIBCPP_STRING_VIEW
12
13/*
14
15    string_view synopsis
16
17#include <compare>
18
19namespace std {
20
21    // 7.2, Class template basic_string_view
22    template<class charT, class traits = char_traits<charT>>
23        class basic_string_view;
24
25    template<class charT, class traits>
26    inline constexpr bool ranges::enable_view<basic_string_view<charT, traits>> = true;
27
28    template<class charT, class traits>
29    inline constexpr bool ranges::enable_borrowed_range<basic_string_view<charT, traits>> = true;  // C++20
30
31    // 7.9, basic_string_view non-member comparison functions
32    template<class charT, class traits>
33    constexpr bool operator==(basic_string_view<charT, traits> x,
34                              basic_string_view<charT, traits> y) noexcept;
35    template<class charT, class traits>                                                            // Removed in C++20
36    constexpr bool operator!=(basic_string_view<charT, traits> x,
37                              basic_string_view<charT, traits> y) noexcept;
38    template<class charT, class traits>                                                            // Removed in C++20
39    constexpr bool operator< (basic_string_view<charT, traits> x,
40                                 basic_string_view<charT, traits> y) noexcept;
41    template<class charT, class traits>                                                            // Removed in C++20
42    constexpr bool operator> (basic_string_view<charT, traits> x,
43                              basic_string_view<charT, traits> y) noexcept;
44    template<class charT, class traits>                                                            // Removed in C++20
45    constexpr bool operator<=(basic_string_view<charT, traits> x,
46                                 basic_string_view<charT, traits> y) noexcept;
47    template<class charT, class traits>                                                            // Removed in C++20
48    constexpr bool operator>=(basic_string_view<charT, traits> x,
49                              basic_string_view<charT, traits> y) noexcept;
50    template<class charT, class traits>                                                            // Since C++20
51    constexpr see below operator<=>(basic_string_view<charT, traits> x,
52                                    basic_string_view<charT, traits> y) noexcept;
53
54    // see below, sufficient additional overloads of comparison functions
55
56    // 7.10, Inserters and extractors
57    template<class charT, class traits>
58      basic_ostream<charT, traits>&
59        operator<<(basic_ostream<charT, traits>& os,
60                   basic_string_view<charT, traits> str);
61
62    // basic_string_view typedef names
63    typedef basic_string_view<char> string_view;
64    typedef basic_string_view<char8_t> u8string_view; // C++20
65    typedef basic_string_view<char16_t> u16string_view;
66    typedef basic_string_view<char32_t> u32string_view;
67    typedef basic_string_view<wchar_t> wstring_view;
68
69    template<class charT, class traits = char_traits<charT>>
70    class basic_string_view {
71      public:
72      // types
73      typedef traits traits_type;
74      typedef charT value_type;
75      typedef charT* pointer;
76      typedef const charT* const_pointer;
77      typedef charT& reference;
78      typedef const charT& const_reference;
79      typedef implementation-defined const_iterator;
80      typedef const_iterator iterator;
81      typedef reverse_iterator<const_iterator> const_reverse_iterator;
82      typedef const_reverse_iterator reverse_iterator;
83      typedef size_t size_type;
84      typedef ptrdiff_t difference_type;
85      static constexpr size_type npos = size_type(-1);
86
87      // 7.3, basic_string_view constructors and assignment operators
88      constexpr basic_string_view() noexcept;
89      constexpr basic_string_view(const basic_string_view&) noexcept = default;
90      basic_string_view& operator=(const basic_string_view&) noexcept = default;
91      template<class Allocator>
92      constexpr basic_string_view(const charT* str);
93      basic_string_view(nullptr_t) = delete; // C++2b
94      constexpr basic_string_view(const charT* str, size_type len);
95      template <class It, class End>
96      constexpr basic_string_view(It begin, End end); // C++20
97      template <class Range>
98      constexpr basic_string_view(Range&& r); // C++23
99
100      // 7.4, basic_string_view iterator support
101      constexpr const_iterator begin() const noexcept;
102      constexpr const_iterator end() const noexcept;
103      constexpr const_iterator cbegin() const noexcept;
104      constexpr const_iterator cend() const noexcept;
105      const_reverse_iterator rbegin() const noexcept;
106      const_reverse_iterator rend() const noexcept;
107      const_reverse_iterator crbegin() const noexcept;
108      const_reverse_iterator crend() const noexcept;
109
110      // 7.5, basic_string_view capacity
111      constexpr size_type size() const noexcept;
112      constexpr size_type length() const noexcept;
113      constexpr size_type max_size() const noexcept;
114      constexpr bool empty() const noexcept;
115
116      // 7.6, basic_string_view element access
117      constexpr const_reference operator[](size_type pos) const;
118      constexpr const_reference at(size_type pos) const;
119      constexpr const_reference front() const;
120      constexpr const_reference back() const;
121      constexpr const_pointer data() const noexcept;
122
123      // 7.7, basic_string_view modifiers
124      constexpr void remove_prefix(size_type n);
125      constexpr void remove_suffix(size_type n);
126      constexpr void swap(basic_string_view& s) noexcept;
127
128      size_type copy(charT* s, size_type n, size_type pos = 0) const;  // constexpr in C++20
129
130      constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
131      constexpr int compare(basic_string_view s) const noexcept;
132      constexpr int compare(size_type pos1, size_type n1, basic_string_view s) const;
133      constexpr int compare(size_type pos1, size_type n1,
134                            basic_string_view s, size_type pos2, size_type n2) const;
135      constexpr int compare(const charT* s) const;
136      constexpr int compare(size_type pos1, size_type n1, const charT* s) const;
137      constexpr int compare(size_type pos1, size_type n1,
138                            const charT* s, size_type n2) const;
139      constexpr size_type find(basic_string_view s, size_type pos = 0) const noexcept;
140      constexpr size_type find(charT c, size_type pos = 0) const noexcept;
141      constexpr size_type find(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
142      constexpr size_type find(const charT* s, size_type pos = 0) const noexcept; // noexcept as an extension
143      constexpr size_type rfind(basic_string_view s, size_type pos = npos) const noexcept;
144      constexpr size_type rfind(charT c, size_type pos = npos) const noexcept;
145      constexpr size_type rfind(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
146      constexpr size_type rfind(const charT* s, size_type pos = npos) const noexcept; // noexcept as an extension
147      constexpr size_type find_first_of(basic_string_view s, size_type pos = 0) const noexcept;
148      constexpr size_type find_first_of(charT c, size_type pos = 0) const noexcept;
149      constexpr size_type find_first_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
150      constexpr size_type find_first_of(const charT* s, size_type pos = 0) const noexcept; // noexcept as an extension
151      constexpr size_type find_last_of(basic_string_view s, size_type pos = npos) const noexcept;
152      constexpr size_type find_last_of(charT c, size_type pos = npos) const noexcept;
153      constexpr size_type find_last_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
154      constexpr size_type find_last_of(const charT* s, size_type pos = npos) const noexcept; // noexcept as an extension
155      constexpr size_type find_first_not_of(basic_string_view s, size_type pos = 0) const noexcept;
156      constexpr size_type find_first_not_of(charT c, size_type pos = 0) const noexcept;
157      constexpr size_type find_first_not_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
158      constexpr size_type find_first_not_of(const charT* s, size_type pos = 0) const noexcept; // noexcept as an extension
159      constexpr size_type find_last_not_of(basic_string_view s, size_type pos = npos) const noexcept;
160      constexpr size_type find_last_not_of(charT c, size_type pos = npos) const noexcept;
161      constexpr size_type find_last_not_of(const charT* s, size_type pos, size_type n) const noexcept; // noexcept as an extension
162      constexpr size_type find_last_not_of(const charT* s, size_type pos = npos) const noexcept; // noexcept as an extension
163
164      constexpr bool starts_with(basic_string_view s) const noexcept; // C++20
165      constexpr bool starts_with(charT c) const noexcept;             // C++20
166      constexpr bool starts_with(const charT* s) const;               // C++20
167      constexpr bool ends_with(basic_string_view s) const noexcept;   // C++20
168      constexpr bool ends_with(charT c) const noexcept;               // C++20
169      constexpr bool ends_with(const charT* s) const;                 // C++20
170
171      constexpr bool contains(basic_string_view s) const noexcept; // C++2b
172      constexpr bool contains(charT c) const noexcept;             // C++2b
173      constexpr bool contains(const charT* s) const;               // C++2b
174
175     private:
176      const_pointer data_;  // exposition only
177      size_type     size_;  // exposition only
178    };
179
180  // basic_string_view deduction guides
181  template<class It, class End>
182    basic_string_view(It, End) -> basic_string_view<iter_value_t<It>>; // C++20
183  template<class Range>
184    basic_string_view(Range&&) -> basic_string_view<ranges::range_value_t<Range>>; // C++23
185
186  // 7.11, Hash support
187  template <class T> struct hash;
188  template <> struct hash<string_view>;
189  template <> struct hash<u8string_view>; // C++20
190  template <> struct hash<u16string_view>;
191  template <> struct hash<u32string_view>;
192  template <> struct hash<wstring_view>;
193
194  constexpr basic_string_view<char>     operator "" sv(const char *str,     size_t len) noexcept;
195  constexpr basic_string_view<wchar_t>  operator "" sv(const wchar_t *str,  size_t len) noexcept;
196  constexpr basic_string_view<char8_t>  operator "" sv(const char8_t *str,  size_t len) noexcept; // C++20
197  constexpr basic_string_view<char16_t> operator "" sv(const char16_t *str, size_t len) noexcept;
198  constexpr basic_string_view<char32_t> operator "" sv(const char32_t *str, size_t len) noexcept;
199
200}  // namespace std
201
202
203*/
204
205#include <__algorithm/min.h>
206#include <__assert> // all public C++ headers provide the assertion handler
207#include <__config>
208#include <__functional/hash.h>
209#include <__functional/unary_function.h>
210#include <__fwd/string_view.h>
211#include <__iterator/bounded_iter.h>
212#include <__iterator/concepts.h>
213#include <__iterator/readable_traits.h>
214#include <__iterator/reverse_iterator.h>
215#include <__memory/pointer_traits.h>
216#include <__ranges/concepts.h>
217#include <__ranges/data.h>
218#include <__ranges/enable_borrowed_range.h>
219#include <__ranges/enable_view.h>
220#include <__ranges/size.h>
221#include <__string/char_traits.h>
222#include <__type_traits/is_array.h>
223#include <__type_traits/is_convertible.h>
224#include <__type_traits/is_same.h>
225#include <__type_traits/is_standard_layout.h>
226#include <__type_traits/is_trivial.h>
227#include <__type_traits/remove_cvref.h>
228#include <__type_traits/remove_reference.h>
229#include <__type_traits/type_identity.h>
230#include <iosfwd>
231#include <limits>
232#include <stdexcept>
233#include <version>
234
235// standard-mandated includes
236
237// [iterator.range]
238#include <__iterator/access.h>
239#include <__iterator/data.h>
240#include <__iterator/empty.h>
241#include <__iterator/reverse_access.h>
242#include <__iterator/size.h>
243
244// [string.view.synop]
245#include <compare>
246
247#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
248#  pragma GCC system_header
249#endif
250
251_LIBCPP_PUSH_MACROS
252#include <__undef_macros>
253
254
255_LIBCPP_BEGIN_NAMESPACE_STD
256
257// TODO: This is a workaround for some vendors to carry a downstream diff to accept `nullptr` in
258//       string_view constructors. This can be refactored when this exact form isn't needed anymore.
259template <class _Traits>
260_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR
261inline size_t __char_traits_length_checked(const typename _Traits::char_type* __s) _NOEXCEPT {
262  // This needs to be a single statement for C++11 constexpr
263  return _LIBCPP_ASSERT(__s != nullptr, "null pointer passed to non-null argument of char_traits<...>::length"), _Traits::length(__s);
264}
265
266template<class _CharT, class _Traits>
267class basic_string_view {
268public:
269    // types
270    using traits_type            = _Traits;
271    using value_type             = _CharT;
272    using pointer                = _CharT*;
273    using const_pointer          = const _CharT*;
274    using reference              = _CharT&;
275    using const_reference        = const _CharT&;
276#ifdef _LIBCPP_DEBUG_ITERATOR_BOUNDS_CHECKING
277    using const_iterator         = __bounded_iter<const_pointer>;
278#else
279    using const_iterator         = const_pointer; // See [string.view.iterators]
280#endif
281    using iterator               = const_iterator;
282    using const_reverse_iterator = _VSTD::reverse_iterator<const_iterator>;
283    using reverse_iterator       = const_reverse_iterator;
284    using size_type              = size_t;
285    using difference_type        = ptrdiff_t;
286    static _LIBCPP_CONSTEXPR const size_type npos = -1; // size_type(-1);
287
288    static_assert((!is_array<value_type>::value), "Character type of basic_string_view must not be an array");
289    static_assert(( is_standard_layout<value_type>::value), "Character type of basic_string_view must be standard-layout");
290    static_assert(( is_trivial<value_type>::value), "Character type of basic_string_view must be trivial");
291    static_assert((is_same<_CharT, typename traits_type::char_type>::value),
292                  "traits_type::char_type must be the same type as CharT");
293
294    // [string.view.cons], construct/copy
295    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
296    basic_string_view() _NOEXCEPT : __data_(nullptr), __size_(0) {}
297
298    _LIBCPP_INLINE_VISIBILITY
299    basic_string_view(const basic_string_view&) _NOEXCEPT = default;
300
301    _LIBCPP_INLINE_VISIBILITY
302    basic_string_view& operator=(const basic_string_view&) _NOEXCEPT = default;
303
304    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
305    basic_string_view(const _CharT* __s, size_type __len) _NOEXCEPT
306        : __data_(__s), __size_(__len)
307    {
308#if _LIBCPP_STD_VER >= 14
309    _LIBCPP_ASSERT(__len <= static_cast<size_type>(numeric_limits<difference_type>::max()), "string_view::string_view(_CharT *, size_t): length does not fit in difference_type");
310    _LIBCPP_ASSERT(__len == 0 || __s != nullptr, "string_view::string_view(_CharT *, size_t): received nullptr");
311#endif
312    }
313
314#if _LIBCPP_STD_VER >= 20
315    template <contiguous_iterator _It, sized_sentinel_for<_It> _End>
316      requires (is_same_v<iter_value_t<_It>, _CharT> && !is_convertible_v<_End, size_type>)
317    constexpr _LIBCPP_HIDE_FROM_ABI basic_string_view(_It __begin, _End __end)
318       : __data_(_VSTD::to_address(__begin)), __size_(__end - __begin)
319    {
320      _LIBCPP_ASSERT((__end - __begin) >= 0, "std::string_view::string_view(iterator, sentinel) received invalid range");
321    }
322#endif // _LIBCPP_STD_VER >= 20
323
324#if _LIBCPP_STD_VER >= 23
325    template <class _Range>
326      requires (
327        !is_same_v<remove_cvref_t<_Range>, basic_string_view> &&
328        ranges::contiguous_range<_Range> &&
329        ranges::sized_range<_Range> &&
330        is_same_v<ranges::range_value_t<_Range>, _CharT> &&
331        !is_convertible_v<_Range, const _CharT*> &&
332        (!requires(remove_cvref_t<_Range>& __d) {
333          __d.operator _VSTD::basic_string_view<_CharT, _Traits>();
334        })
335      )
336    constexpr explicit _LIBCPP_HIDE_FROM_ABI
337    basic_string_view(_Range&& __r) : __data_(ranges::data(__r)), __size_(ranges::size(__r)) {}
338#endif // _LIBCPP_STD_VER >= 23
339
340    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
341    basic_string_view(const _CharT* __s)
342        : __data_(__s), __size_(_VSTD::__char_traits_length_checked<_Traits>(__s)) {}
343
344#if _LIBCPP_STD_VER >= 23
345    basic_string_view(nullptr_t) = delete;
346#endif
347
348    // [string.view.iterators], iterators
349    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
350    const_iterator begin()  const _NOEXCEPT { return cbegin(); }
351
352    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
353    const_iterator end()    const _NOEXCEPT { return cend(); }
354
355    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
356    const_iterator cbegin() const _NOEXCEPT {
357#ifdef _LIBCPP_DEBUG_ITERATOR_BOUNDS_CHECKING
358        return std::__make_bounded_iter(data(), data(), data() + size());
359#else
360        return __data_;
361#endif
362    }
363
364    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
365    const_iterator cend()   const _NOEXCEPT {
366#ifdef _LIBCPP_DEBUG_ITERATOR_BOUNDS_CHECKING
367        return std::__make_bounded_iter(data() + size(), data(), data() + size());
368#else
369        return __data_ + __size_;
370#endif
371    }
372
373    _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_INLINE_VISIBILITY
374    const_reverse_iterator rbegin()   const _NOEXCEPT { return const_reverse_iterator(cend()); }
375
376    _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_INLINE_VISIBILITY
377    const_reverse_iterator rend()     const _NOEXCEPT { return const_reverse_iterator(cbegin()); }
378
379    _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_INLINE_VISIBILITY
380    const_reverse_iterator crbegin()  const _NOEXCEPT { return const_reverse_iterator(cend()); }
381
382    _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_INLINE_VISIBILITY
383    const_reverse_iterator crend()    const _NOEXCEPT { return const_reverse_iterator(cbegin()); }
384
385    // [string.view.capacity], capacity
386    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
387    size_type size()     const _NOEXCEPT { return __size_; }
388
389    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
390    size_type length()   const _NOEXCEPT { return __size_; }
391
392    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
393    size_type max_size() const _NOEXCEPT { return numeric_limits<size_type>::max() / sizeof(value_type); }
394
395    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
396    bool empty()         const _NOEXCEPT { return __size_ == 0; }
397
398    // [string.view.access], element access
399    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
400    const_reference operator[](size_type __pos) const _NOEXCEPT {
401      return _LIBCPP_ASSERT(__pos < size(), "string_view[] index out of bounds"), __data_[__pos];
402    }
403
404    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
405    const_reference at(size_type __pos) const
406    {
407        return __pos >= size()
408            ? (__throw_out_of_range("string_view::at"), __data_[0])
409            : __data_[__pos];
410    }
411
412    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
413    const_reference front() const _NOEXCEPT
414    {
415        return _LIBCPP_ASSERT(!empty(), "string_view::front(): string is empty"), __data_[0];
416    }
417
418    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
419    const_reference back() const _NOEXCEPT
420    {
421        return _LIBCPP_ASSERT(!empty(), "string_view::back(): string is empty"), __data_[__size_-1];
422    }
423
424    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
425    const_pointer data() const _NOEXCEPT { return __data_; }
426
427    // [string.view.modifiers], modifiers:
428    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
429    void remove_prefix(size_type __n) _NOEXCEPT
430    {
431        _LIBCPP_ASSERT(__n <= size(), "remove_prefix() can't remove more than size()");
432        __data_ += __n;
433        __size_ -= __n;
434    }
435
436    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
437    void remove_suffix(size_type __n) _NOEXCEPT
438    {
439        _LIBCPP_ASSERT(__n <= size(), "remove_suffix() can't remove more than size()");
440        __size_ -= __n;
441    }
442
443    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
444    void swap(basic_string_view& __other) _NOEXCEPT
445    {
446        const value_type *__p = __data_;
447        __data_ = __other.__data_;
448        __other.__data_ = __p;
449
450        size_type __sz = __size_;
451        __size_ = __other.__size_;
452        __other.__size_ = __sz;
453    }
454
455    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
456    size_type copy(_CharT* __s, size_type __n, size_type __pos = 0) const
457    {
458        if (__pos > size())
459            __throw_out_of_range("string_view::copy");
460        size_type __rlen = _VSTD::min(__n, size() - __pos);
461        _Traits::copy(__s, data() + __pos, __rlen);
462        return __rlen;
463    }
464
465    _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
466    basic_string_view substr(size_type __pos = 0, size_type __n = npos) const
467    {
468        return __pos > size()
469            ? (__throw_out_of_range("string_view::substr"), basic_string_view())
470            : basic_string_view(data() + __pos, _VSTD::min(__n, size() - __pos));
471    }
472
473    _LIBCPP_CONSTEXPR_SINCE_CXX14 int compare(basic_string_view __sv) const _NOEXCEPT
474    {
475        size_type __rlen = _VSTD::min(size(), __sv.size());
476        int __retval = _Traits::compare(data(), __sv.data(), __rlen);
477        if (__retval == 0) // first __rlen chars matched
478            __retval = size() == __sv.size() ? 0 : (size() < __sv.size() ? -1 : 1);
479        return __retval;
480    }
481
482    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
483    int compare(size_type __pos1, size_type __n1, basic_string_view __sv) const
484    {
485        return substr(__pos1, __n1).compare(__sv);
486    }
487
488    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
489    int compare(                       size_type __pos1, size_type __n1,
490                basic_string_view __sv, size_type __pos2, size_type __n2) const
491    {
492        return substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
493    }
494
495    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
496    int compare(const _CharT* __s) const _NOEXCEPT
497    {
498        return compare(basic_string_view(__s));
499    }
500
501    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
502    int compare(size_type __pos1, size_type __n1, const _CharT* __s) const
503    {
504        return substr(__pos1, __n1).compare(basic_string_view(__s));
505    }
506
507    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
508    int compare(size_type __pos1, size_type __n1, const _CharT* __s, size_type __n2) const
509    {
510        return substr(__pos1, __n1).compare(basic_string_view(__s, __n2));
511    }
512
513    // find
514    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
515    size_type find(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT
516    {
517        _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find(): received nullptr");
518        return std::__str_find<value_type, size_type, traits_type, npos>
519            (data(), size(), __s.data(), __pos, __s.size());
520    }
521
522    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
523    size_type find(_CharT __c, size_type __pos = 0) const _NOEXCEPT
524    {
525        return std::__str_find<value_type, size_type, traits_type, npos>
526            (data(), size(), __c, __pos);
527    }
528
529    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
530    size_type find(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
531    {
532        _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find(): received nullptr");
533        return std::__str_find<value_type, size_type, traits_type, npos>
534            (data(), size(), __s, __pos, __n);
535    }
536
537    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
538    size_type find(const _CharT* __s, size_type __pos = 0) const _NOEXCEPT
539    {
540        _LIBCPP_ASSERT(__s != nullptr, "string_view::find(): received nullptr");
541        return std::__str_find<value_type, size_type, traits_type, npos>
542            (data(), size(), __s, __pos, traits_type::length(__s));
543    }
544
545    // rfind
546    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
547    size_type rfind(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT
548    {
549        _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find(): received nullptr");
550        return std::__str_rfind<value_type, size_type, traits_type, npos>
551            (data(), size(), __s.data(), __pos, __s.size());
552    }
553
554    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
555    size_type rfind(_CharT __c, size_type __pos = npos) const _NOEXCEPT
556    {
557        return std::__str_rfind<value_type, size_type, traits_type, npos>
558            (data(), size(), __c, __pos);
559    }
560
561    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
562    size_type rfind(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
563    {
564        _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::rfind(): received nullptr");
565        return std::__str_rfind<value_type, size_type, traits_type, npos>
566            (data(), size(), __s, __pos, __n);
567    }
568
569    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
570    size_type rfind(const _CharT* __s, size_type __pos=npos) const _NOEXCEPT
571    {
572        _LIBCPP_ASSERT(__s != nullptr, "string_view::rfind(): received nullptr");
573        return std::__str_rfind<value_type, size_type, traits_type, npos>
574            (data(), size(), __s, __pos, traits_type::length(__s));
575    }
576
577    // find_first_of
578    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
579    size_type find_first_of(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT
580    {
581        _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_first_of(): received nullptr");
582        return std::__str_find_first_of<value_type, size_type, traits_type, npos>
583            (data(), size(), __s.data(), __pos, __s.size());
584    }
585
586    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
587    size_type find_first_of(_CharT __c, size_type __pos = 0) const _NOEXCEPT
588    { return find(__c, __pos); }
589
590    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
591    size_type find_first_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
592    {
593        _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_first_of(): received nullptr");
594        return std::__str_find_first_of<value_type, size_type, traits_type, npos>
595            (data(), size(), __s, __pos, __n);
596    }
597
598    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
599    size_type find_first_of(const _CharT* __s, size_type __pos=0) const _NOEXCEPT
600    {
601        _LIBCPP_ASSERT(__s != nullptr, "string_view::find_first_of(): received nullptr");
602        return std::__str_find_first_of<value_type, size_type, traits_type, npos>
603            (data(), size(), __s, __pos, traits_type::length(__s));
604    }
605
606    // find_last_of
607    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
608    size_type find_last_of(basic_string_view __s, size_type __pos=npos) const _NOEXCEPT
609    {
610        _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_last_of(): received nullptr");
611        return std::__str_find_last_of<value_type, size_type, traits_type, npos>
612            (data(), size(), __s.data(), __pos, __s.size());
613    }
614
615    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
616    size_type find_last_of(_CharT __c, size_type __pos = npos) const _NOEXCEPT
617    { return rfind(__c, __pos); }
618
619    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
620    size_type find_last_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
621    {
622        _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_last_of(): received nullptr");
623        return std::__str_find_last_of<value_type, size_type, traits_type, npos>
624            (data(), size(), __s, __pos, __n);
625    }
626
627    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
628    size_type find_last_of(const _CharT* __s, size_type __pos=npos) const _NOEXCEPT
629    {
630        _LIBCPP_ASSERT(__s != nullptr, "string_view::find_last_of(): received nullptr");
631        return std::__str_find_last_of<value_type, size_type, traits_type, npos>
632            (data(), size(), __s, __pos, traits_type::length(__s));
633    }
634
635    // find_first_not_of
636    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
637    size_type find_first_not_of(basic_string_view __s, size_type __pos=0) const _NOEXCEPT
638    {
639        _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_first_not_of(): received nullptr");
640        return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>
641            (data(), size(), __s.data(), __pos, __s.size());
642    }
643
644    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
645    size_type find_first_not_of(_CharT __c, size_type __pos=0) const _NOEXCEPT
646    {
647        return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>
648            (data(), size(), __c, __pos);
649    }
650
651    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
652    size_type find_first_not_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
653    {
654        _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_first_not_of(): received nullptr");
655        return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>
656            (data(), size(), __s, __pos, __n);
657    }
658
659    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
660    size_type find_first_not_of(const _CharT* __s, size_type __pos=0) const _NOEXCEPT
661    {
662        _LIBCPP_ASSERT(__s != nullptr, "string_view::find_first_not_of(): received nullptr");
663        return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>
664            (data(), size(), __s, __pos, traits_type::length(__s));
665    }
666
667    // find_last_not_of
668    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
669    size_type find_last_not_of(basic_string_view __s, size_type __pos=npos) const _NOEXCEPT
670    {
671        _LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_last_not_of(): received nullptr");
672        return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>
673            (data(), size(), __s.data(), __pos, __s.size());
674    }
675
676    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
677    size_type find_last_not_of(_CharT __c, size_type __pos=npos) const _NOEXCEPT
678    {
679        return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>
680            (data(), size(), __c, __pos);
681    }
682
683    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
684    size_type find_last_not_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
685    {
686        _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_last_not_of(): received nullptr");
687        return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>
688            (data(), size(), __s, __pos, __n);
689    }
690
691    _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
692    size_type find_last_not_of(const _CharT* __s, size_type __pos=npos) const _NOEXCEPT
693    {
694        _LIBCPP_ASSERT(__s != nullptr, "string_view::find_last_not_of(): received nullptr");
695        return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>
696            (data(), size(), __s, __pos, traits_type::length(__s));
697    }
698
699#if _LIBCPP_STD_VER >= 20
700    constexpr _LIBCPP_INLINE_VISIBILITY
701    bool starts_with(basic_string_view __s) const noexcept
702    { return size() >= __s.size() && compare(0, __s.size(), __s) == 0; }
703
704    constexpr _LIBCPP_INLINE_VISIBILITY
705    bool starts_with(value_type __c) const noexcept
706    { return !empty() && _Traits::eq(front(), __c); }
707
708    constexpr _LIBCPP_INLINE_VISIBILITY
709    bool starts_with(const value_type* __s) const noexcept
710    { return starts_with(basic_string_view(__s)); }
711
712    constexpr _LIBCPP_INLINE_VISIBILITY
713    bool ends_with(basic_string_view __s) const noexcept
714    { return size() >= __s.size() && compare(size() - __s.size(), npos, __s) == 0; }
715
716    constexpr _LIBCPP_INLINE_VISIBILITY
717    bool ends_with(value_type __c) const noexcept
718    { return !empty() && _Traits::eq(back(), __c); }
719
720    constexpr _LIBCPP_INLINE_VISIBILITY
721    bool ends_with(const value_type* __s) const noexcept
722    { return ends_with(basic_string_view(__s)); }
723#endif
724
725#if _LIBCPP_STD_VER >= 23
726    constexpr _LIBCPP_INLINE_VISIBILITY
727    bool contains(basic_string_view __sv) const noexcept
728    { return find(__sv) != npos; }
729
730    constexpr _LIBCPP_INLINE_VISIBILITY
731    bool contains(value_type __c) const noexcept
732    { return find(__c) != npos; }
733
734    constexpr _LIBCPP_INLINE_VISIBILITY
735    bool contains(const value_type* __s) const
736    { return find(__s) != npos; }
737#endif
738
739private:
740    const   value_type* __data_;
741    size_type           __size_;
742};
743_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(basic_string_view);
744
745#if _LIBCPP_STD_VER >= 20
746template <class _CharT, class _Traits>
747inline constexpr bool ranges::enable_view<basic_string_view<_CharT, _Traits>> = true;
748
749template <class _CharT, class _Traits>
750inline constexpr bool ranges::enable_borrowed_range<basic_string_view<_CharT, _Traits> > = true;
751#endif // _LIBCPP_STD_VER >= 20
752
753// [string.view.deduct]
754
755#if _LIBCPP_STD_VER >= 20
756template <contiguous_iterator _It, sized_sentinel_for<_It> _End>
757  basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
758#endif // _LIBCPP_STD_VER >= 20
759
760
761#if _LIBCPP_STD_VER >= 23
762template <ranges::contiguous_range _Range>
763  basic_string_view(_Range) -> basic_string_view<ranges::range_value_t<_Range>>;
764#endif
765
766// [string.view.comparison]
767// operator ==
768template<class _CharT, class _Traits>
769_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
770bool operator==(basic_string_view<_CharT, _Traits> __lhs,
771                basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
772{
773    if (__lhs.size() != __rhs.size()) return false;
774    return __lhs.compare(__rhs) == 0;
775}
776
777// The dummy default template parameters are used to work around a MSVC issue with mangling, see VSO-409326 for details.
778// This applies to the other sufficient overloads below for the other comparison operators.
779template<class _CharT, class _Traits, int = 1>
780_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
781bool operator==(basic_string_view<_CharT, _Traits> __lhs,
782                __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT
783{
784    if (__lhs.size() != __rhs.size()) return false;
785    return __lhs.compare(__rhs) == 0;
786}
787
788#if _LIBCPP_STD_VER < 20
789// This overload is automatically generated in C++20.
790template<class _CharT, class _Traits, int = 2>
791_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
792bool operator==(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
793                basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
794{
795    if (__lhs.size() != __rhs.size()) return false;
796    return __lhs.compare(__rhs) == 0;
797}
798#endif // _LIBCPP_STD_VER >= 20
799
800// operator <=>
801
802#if _LIBCPP_STD_VER >= 20
803
804template <class _CharT, class _Traits>
805_LIBCPP_HIDE_FROM_ABI constexpr auto
806operator<=>(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) noexcept {
807    if constexpr (requires { typename _Traits::comparison_category; }) {
808        // [string.view]/4
809        static_assert(
810            __comparison_category<typename _Traits::comparison_category>,
811            "return type is not a comparison category type");
812        return static_cast<typename _Traits::comparison_category>(__lhs.compare(__rhs) <=> 0);
813    } else {
814        return static_cast<weak_ordering>(__lhs.compare(__rhs) <=> 0);
815    }
816}
817
818template <class _CharT, class _Traits, int = 1>
819_LIBCPP_HIDE_FROM_ABI constexpr auto operator<=>(
820    basic_string_view<_CharT, _Traits> __lhs, type_identity_t<basic_string_view<_CharT, _Traits>> __rhs) noexcept {
821    if constexpr (requires { typename _Traits::comparison_category; }) {
822        // [string.view]/4
823        static_assert(
824            __comparison_category<typename _Traits::comparison_category>,
825            "return type is not a comparison category type");
826        return static_cast<typename _Traits::comparison_category>(__lhs.compare(__rhs) <=> 0);
827    } else {
828        return static_cast<weak_ordering>(__lhs.compare(__rhs) <=> 0);
829    }
830}
831
832#else //  _LIBCPP_STD_VER >= 20
833
834// operator !=
835template<class _CharT, class _Traits>
836_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
837bool operator!=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
838{
839    if (__lhs.size() != __rhs.size())
840        return true;
841    return __lhs.compare(__rhs) != 0;
842}
843
844template<class _CharT, class _Traits, int = 1>
845_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
846bool operator!=(basic_string_view<_CharT, _Traits> __lhs,
847                __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT
848{
849    if (__lhs.size() != __rhs.size())
850        return true;
851    return __lhs.compare(__rhs) != 0;
852}
853
854template<class _CharT, class _Traits, int = 2>
855_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
856bool operator!=(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
857                basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
858{
859    if (__lhs.size() != __rhs.size())
860        return true;
861    return __lhs.compare(__rhs) != 0;
862}
863
864
865// operator <
866template<class _CharT, class _Traits>
867_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
868bool operator<(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
869{
870    return __lhs.compare(__rhs) < 0;
871}
872
873template<class _CharT, class _Traits, int = 1>
874_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
875bool operator<(basic_string_view<_CharT, _Traits> __lhs,
876                __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT
877{
878    return __lhs.compare(__rhs) < 0;
879}
880
881template<class _CharT, class _Traits, int = 2>
882_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
883bool operator<(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
884                basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
885{
886    return __lhs.compare(__rhs) < 0;
887}
888
889
890// operator >
891template<class _CharT, class _Traits>
892_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
893bool operator> (basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
894{
895    return __lhs.compare(__rhs) > 0;
896}
897
898template<class _CharT, class _Traits, int = 1>
899_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
900bool operator>(basic_string_view<_CharT, _Traits> __lhs,
901                __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT
902{
903    return __lhs.compare(__rhs) > 0;
904}
905
906template<class _CharT, class _Traits, int = 2>
907_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
908bool operator>(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
909                basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
910{
911    return __lhs.compare(__rhs) > 0;
912}
913
914
915// operator <=
916template<class _CharT, class _Traits>
917_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
918bool operator<=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
919{
920    return __lhs.compare(__rhs) <= 0;
921}
922
923template<class _CharT, class _Traits, int = 1>
924_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
925bool operator<=(basic_string_view<_CharT, _Traits> __lhs,
926                __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT
927{
928    return __lhs.compare(__rhs) <= 0;
929}
930
931template<class _CharT, class _Traits, int = 2>
932_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
933bool operator<=(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
934                basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
935{
936    return __lhs.compare(__rhs) <= 0;
937}
938
939
940// operator >=
941template<class _CharT, class _Traits>
942_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
943bool operator>=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
944{
945    return __lhs.compare(__rhs) >= 0;
946}
947
948
949template<class _CharT, class _Traits, int = 1>
950_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
951bool operator>=(basic_string_view<_CharT, _Traits> __lhs,
952                __type_identity_t<basic_string_view<_CharT, _Traits> > __rhs) _NOEXCEPT
953{
954    return __lhs.compare(__rhs) >= 0;
955}
956
957template<class _CharT, class _Traits, int = 2>
958_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_INLINE_VISIBILITY
959bool operator>=(__type_identity_t<basic_string_view<_CharT, _Traits> > __lhs,
960                basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
961{
962    return __lhs.compare(__rhs) >= 0;
963}
964
965#endif //  _LIBCPP_STD_VER >= 20
966
967template<class _CharT, class _Traits>
968_LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
969operator<<(basic_ostream<_CharT, _Traits>& __os,
970           basic_string_view<_CharT, _Traits> __str);
971
972// [string.view.hash]
973template<class _CharT>
974struct __string_view_hash : public __unary_function<basic_string_view<_CharT, char_traits<_CharT> >, size_t>
975{
976    _LIBCPP_INLINE_VISIBILITY
977    size_t operator()(const basic_string_view<_CharT, char_traits<_CharT> > __val) const _NOEXCEPT {
978        return std::__do_string_hash(__val.data(), __val.data() + __val.size());
979    }
980};
981
982template <>
983struct hash<basic_string_view<char, char_traits<char> > > : __string_view_hash<char> {};
984
985#ifndef _LIBCPP_HAS_NO_CHAR8_T
986template <>
987struct hash<basic_string_view<char8_t, char_traits<char8_t> > > : __string_view_hash<char8_t> {};
988#endif
989
990template <>
991struct hash<basic_string_view<char16_t, char_traits<char16_t> > > : __string_view_hash<char16_t> {};
992
993template <>
994struct hash<basic_string_view<char32_t, char_traits<char32_t> > > : __string_view_hash<char32_t> {};
995
996#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
997template <>
998struct hash<basic_string_view<wchar_t, char_traits<wchar_t> > > : __string_view_hash<wchar_t> {};
999#endif
1000
1001#if _LIBCPP_STD_VER >= 14
1002inline namespace literals
1003{
1004  inline namespace string_view_literals
1005  {
1006    inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
1007    basic_string_view<char> operator "" sv(const char *__str, size_t __len) _NOEXCEPT
1008    {
1009        return basic_string_view<char> (__str, __len);
1010    }
1011
1012#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
1013    inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
1014    basic_string_view<wchar_t> operator "" sv(const wchar_t *__str, size_t __len) _NOEXCEPT
1015    {
1016        return basic_string_view<wchar_t> (__str, __len);
1017    }
1018#endif
1019
1020#ifndef _LIBCPP_HAS_NO_CHAR8_T
1021    inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
1022    basic_string_view<char8_t> operator "" sv(const char8_t *__str, size_t __len) _NOEXCEPT
1023    {
1024        return basic_string_view<char8_t> (__str, __len);
1025    }
1026#endif
1027
1028    inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
1029    basic_string_view<char16_t> operator "" sv(const char16_t *__str, size_t __len) _NOEXCEPT
1030    {
1031        return basic_string_view<char16_t> (__str, __len);
1032    }
1033
1034    inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
1035    basic_string_view<char32_t> operator "" sv(const char32_t *__str, size_t __len) _NOEXCEPT
1036    {
1037        return basic_string_view<char32_t> (__str, __len);
1038    }
1039  } // namespace string_view_literals
1040} // namespace literals
1041#endif
1042_LIBCPP_END_NAMESPACE_STD
1043
1044_LIBCPP_POP_MACROS
1045
1046#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
1047#  include <algorithm>
1048#  include <concepts>
1049#  include <cstdlib>
1050#  include <functional>
1051#  include <iterator>
1052#  include <type_traits>
1053#endif
1054
1055#endif // _LIBCPP_STRING_VIEW
1056