xref: /llvm-project-15.0.7/libcxx/include/string (revision b7fd91c8)
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
11#define _LIBCPP_STRING
12
13/*
14    string synopsis
15
16namespace std
17{
18
19template <class stateT>
20class fpos
21{
22private:
23    stateT st;
24public:
25    fpos(streamoff = streamoff());
26
27    operator streamoff() const;
28
29    stateT state() const;
30    void state(stateT);
31
32    fpos& operator+=(streamoff);
33    fpos  operator+ (streamoff) const;
34    fpos& operator-=(streamoff);
35    fpos  operator- (streamoff) const;
36};
37
38template <class stateT> streamoff operator-(const fpos<stateT>& x, const fpos<stateT>& y);
39
40template <class stateT> bool operator==(const fpos<stateT>& x, const fpos<stateT>& y);
41template <class stateT> bool operator!=(const fpos<stateT>& x, const fpos<stateT>& y);
42
43template <class charT>
44struct char_traits
45{
46    typedef charT     char_type;
47    typedef ...       int_type;
48    typedef streamoff off_type;
49    typedef streampos pos_type;
50    typedef mbstate_t state_type;
51
52    static void assign(char_type& c1, const char_type& c2) noexcept;
53    static constexpr bool eq(char_type c1, char_type c2) noexcept;
54    static constexpr bool lt(char_type c1, char_type c2) noexcept;
55
56    static int              compare(const char_type* s1, const char_type* s2, size_t n);
57    static size_t           length(const char_type* s);
58    static const char_type* find(const char_type* s, size_t n, const char_type& a);
59    static char_type*       move(char_type* s1, const char_type* s2, size_t n);
60    static char_type*       copy(char_type* s1, const char_type* s2, size_t n);
61    static char_type*       assign(char_type* s, size_t n, char_type a);
62
63    static constexpr int_type  not_eof(int_type c) noexcept;
64    static constexpr char_type to_char_type(int_type c) noexcept;
65    static constexpr int_type  to_int_type(char_type c) noexcept;
66    static constexpr bool      eq_int_type(int_type c1, int_type c2) noexcept;
67    static constexpr int_type  eof() noexcept;
68};
69
70template <> struct char_traits<char>;
71template <> struct char_traits<wchar_t>;
72template <> struct char_traits<char8_t>;  // C++20
73template <> struct char_traits<char16_t>;
74template <> struct char_traits<char32_t>;
75
76template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
77class basic_string
78{
79public:
80// types:
81    typedef traits traits_type;
82    typedef typename traits_type::char_type value_type;
83    typedef Allocator allocator_type;
84    typedef typename allocator_type::size_type size_type;
85    typedef typename allocator_type::difference_type difference_type;
86    typedef typename allocator_type::reference reference;
87    typedef typename allocator_type::const_reference const_reference;
88    typedef typename allocator_type::pointer pointer;
89    typedef typename allocator_type::const_pointer const_pointer;
90    typedef implementation-defined iterator;
91    typedef implementation-defined const_iterator;
92    typedef std::reverse_iterator<iterator> reverse_iterator;
93    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
94
95    static const size_type npos = -1;
96
97    basic_string()
98        noexcept(is_nothrow_default_constructible<allocator_type>::value);
99    explicit basic_string(const allocator_type& a);
100    basic_string(const basic_string& str);
101    basic_string(basic_string&& str)
102        noexcept(is_nothrow_move_constructible<allocator_type>::value);
103    basic_string(const basic_string& str, size_type pos,
104                 const allocator_type& a = allocator_type());
105    basic_string(const basic_string& str, size_type pos, size_type n,
106                 const Allocator& a = Allocator());
107    template<class T>
108        basic_string(const T& t, size_type pos, size_type n, const Allocator& a = Allocator()); // C++17
109    template <class T>
110        explicit basic_string(const T& t, const Allocator& a = Allocator()); // C++17
111    basic_string(const value_type* s, const allocator_type& a = allocator_type());
112    basic_string(const value_type* s, size_type n, const allocator_type& a = allocator_type());
113    basic_string(nullptr_t) = delete; // C++2b
114    basic_string(size_type n, value_type c, const allocator_type& a = allocator_type());
115    template<class InputIterator>
116        basic_string(InputIterator begin, InputIterator end,
117                     const allocator_type& a = allocator_type());
118    basic_string(initializer_list<value_type>, const Allocator& = Allocator());
119    basic_string(const basic_string&, const Allocator&);
120    basic_string(basic_string&&, const Allocator&);
121
122    ~basic_string();
123
124    operator basic_string_view<charT, traits>() const noexcept;
125
126    basic_string& operator=(const basic_string& str);
127    template <class T>
128        basic_string& operator=(const T& t); // C++17
129    basic_string& operator=(basic_string&& str)
130        noexcept(
131             allocator_type::propagate_on_container_move_assignment::value ||
132             allocator_type::is_always_equal::value ); // C++17
133    basic_string& operator=(const value_type* s);
134    basic_string& operator=(nullptr_t) = delete; // C++2b
135    basic_string& operator=(value_type c);
136    basic_string& operator=(initializer_list<value_type>);
137
138    iterator       begin() noexcept;
139    const_iterator begin() const noexcept;
140    iterator       end() noexcept;
141    const_iterator end() const noexcept;
142
143    reverse_iterator       rbegin() noexcept;
144    const_reverse_iterator rbegin() const noexcept;
145    reverse_iterator       rend() noexcept;
146    const_reverse_iterator rend() const noexcept;
147
148    const_iterator         cbegin() const noexcept;
149    const_iterator         cend() const noexcept;
150    const_reverse_iterator crbegin() const noexcept;
151    const_reverse_iterator crend() const noexcept;
152
153    size_type size() const noexcept;
154    size_type length() const noexcept;
155    size_type max_size() const noexcept;
156    size_type capacity() const noexcept;
157
158    void resize(size_type n, value_type c);
159    void resize(size_type n);
160
161    template<class Operation>
162    constexpr void resize_and_overwrite(size_type n, Operation op); // since C++23
163
164    void reserve(size_type res_arg);
165    void reserve(); // deprecated in C++20
166    void shrink_to_fit();
167    void clear() noexcept;
168    bool empty() const noexcept;
169
170    const_reference operator[](size_type pos) const;
171    reference       operator[](size_type pos);
172
173    const_reference at(size_type n) const;
174    reference       at(size_type n);
175
176    basic_string& operator+=(const basic_string& str);
177    template <class T>
178        basic_string& operator+=(const T& t);              // C++17
179    basic_string& operator+=(const value_type* s);
180    basic_string& operator+=(value_type c);
181    basic_string& operator+=(initializer_list<value_type>);
182
183    basic_string& append(const basic_string& str);
184    template <class T>
185        basic_string& append(const T& t);                 // C++17
186    basic_string& append(const basic_string& str, size_type pos, size_type n=npos); //C++14
187    template <class T>
188        basic_string& append(const T& t, size_type pos, size_type n=npos); // C++17
189    basic_string& append(const value_type* s, size_type n);
190    basic_string& append(const value_type* s);
191    basic_string& append(size_type n, value_type c);
192    template<class InputIterator>
193        basic_string& append(InputIterator first, InputIterator last);
194    basic_string& append(initializer_list<value_type>);
195
196    void push_back(value_type c);
197    void pop_back();
198    reference       front();
199    const_reference front() const;
200    reference       back();
201    const_reference back() const;
202
203    basic_string& assign(const basic_string& str);
204    template <class T>
205        basic_string& assign(const T& t);  // C++17
206    basic_string& assign(basic_string&& str);
207    basic_string& assign(const basic_string& str, size_type pos, size_type n=npos); // C++14
208    template <class T>
209        basic_string& assign(const T& t, size_type pos, size_type n=npos); // C++17
210    basic_string& assign(const value_type* s, size_type n);
211    basic_string& assign(const value_type* s);
212    basic_string& assign(size_type n, value_type c);
213    template<class InputIterator>
214        basic_string& assign(InputIterator first, InputIterator last);
215    basic_string& assign(initializer_list<value_type>);
216
217    basic_string& insert(size_type pos1, const basic_string& str);
218    template <class T>
219        basic_string& insert(size_type pos1, const T& t);
220    basic_string& insert(size_type pos1, const basic_string& str,
221                         size_type pos2, size_type n);
222    template <class T>
223        basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n); // C++17
224    basic_string& insert(size_type pos, const value_type* s, size_type n=npos); //C++14
225    basic_string& insert(size_type pos, const value_type* s);
226    basic_string& insert(size_type pos, size_type n, value_type c);
227    iterator      insert(const_iterator p, value_type c);
228    iterator      insert(const_iterator p, size_type n, value_type c);
229    template<class InputIterator>
230        iterator insert(const_iterator p, InputIterator first, InputIterator last);
231    iterator      insert(const_iterator p, initializer_list<value_type>);
232
233    basic_string& erase(size_type pos = 0, size_type n = npos);
234    iterator      erase(const_iterator position);
235    iterator      erase(const_iterator first, const_iterator last);
236
237    basic_string& replace(size_type pos1, size_type n1, const basic_string& str);
238    template <class T>
239    basic_string& replace(size_type pos1, size_type n1, const T& t);  // C++17
240    basic_string& replace(size_type pos1, size_type n1, const basic_string& str,
241                          size_type pos2, size_type n2=npos); // C++14
242    template <class T>
243        basic_string& replace(size_type pos1, size_type n1, const T& t,
244                              size_type pos2, size_type n); // C++17
245    basic_string& replace(size_type pos, size_type n1, const value_type* s, size_type n2);
246    basic_string& replace(size_type pos, size_type n1, const value_type* s);
247    basic_string& replace(size_type pos, size_type n1, size_type n2, value_type c);
248    basic_string& replace(const_iterator i1, const_iterator i2, const basic_string& str);
249    template <class T>
250        basic_string& replace(const_iterator i1, const_iterator i2, const T& t);  // C++17
251    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s, size_type n);
252    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s);
253    basic_string& replace(const_iterator i1, const_iterator i2, size_type n, value_type c);
254    template<class InputIterator>
255        basic_string& replace(const_iterator i1, const_iterator i2, InputIterator j1, InputIterator j2);
256    basic_string& replace(const_iterator i1, const_iterator i2, initializer_list<value_type>);
257
258    size_type copy(value_type* s, size_type n, size_type pos = 0) const;
259    basic_string substr(size_type pos = 0, size_type n = npos) const;
260
261    void swap(basic_string& str)
262        noexcept(allocator_traits<allocator_type>::propagate_on_container_swap::value ||
263                 allocator_traits<allocator_type>::is_always_equal::value);  // C++17
264
265    const value_type* c_str() const noexcept;
266    const value_type* data() const noexcept;
267          value_type* data()       noexcept;   // C++17
268
269    allocator_type get_allocator() const noexcept;
270
271    size_type find(const basic_string& str, size_type pos = 0) const noexcept;
272    template <class T>
273        size_type find(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
274    size_type find(const value_type* s, size_type pos, size_type n) const noexcept;
275    size_type find(const value_type* s, size_type pos = 0) const noexcept;
276    size_type find(value_type c, size_type pos = 0) const noexcept;
277
278    size_type rfind(const basic_string& str, size_type pos = npos) const noexcept;
279    template <class T>
280        size_type rfind(const T& t, size_type pos = npos) const noexcept; // C++17, noexcept as an extension
281    size_type rfind(const value_type* s, size_type pos, size_type n) const noexcept;
282    size_type rfind(const value_type* s, size_type pos = npos) const noexcept;
283    size_type rfind(value_type c, size_type pos = npos) const noexcept;
284
285    size_type find_first_of(const basic_string& str, size_type pos = 0) const noexcept;
286    template <class T>
287        size_type find_first_of(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
288    size_type find_first_of(const value_type* s, size_type pos, size_type n) const noexcept;
289    size_type find_first_of(const value_type* s, size_type pos = 0) const noexcept;
290    size_type find_first_of(value_type c, size_type pos = 0) const noexcept;
291
292    size_type find_last_of(const basic_string& str, size_type pos = npos) const noexcept;
293    template <class T>
294        size_type find_last_of(const T& t, size_type pos = npos) const noexcept noexcept; // C++17, noexcept as an extension
295    size_type find_last_of(const value_type* s, size_type pos, size_type n) const noexcept;
296    size_type find_last_of(const value_type* s, size_type pos = npos) const noexcept;
297    size_type find_last_of(value_type c, size_type pos = npos) const noexcept;
298
299    size_type find_first_not_of(const basic_string& str, size_type pos = 0) const noexcept;
300    template <class T>
301        size_type find_first_not_of(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
302    size_type find_first_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
303    size_type find_first_not_of(const value_type* s, size_type pos = 0) const noexcept;
304    size_type find_first_not_of(value_type c, size_type pos = 0) const noexcept;
305
306    size_type find_last_not_of(const basic_string& str, size_type pos = npos) const noexcept;
307    template <class T>
308        size_type find_last_not_of(const T& t, size_type pos = npos) const noexcept; // C++17, noexcept as an extension
309    size_type find_last_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
310    size_type find_last_not_of(const value_type* s, size_type pos = npos) const noexcept;
311    size_type find_last_not_of(value_type c, size_type pos = npos) const noexcept;
312
313    int compare(const basic_string& str) const noexcept;
314    template <class T>
315        int compare(const T& t) const noexcept;  // C++17, noexcept as an extension
316    int compare(size_type pos1, size_type n1, const basic_string& str) const;
317    template <class T>
318        int compare(size_type pos1, size_type n1, const T& t) const;  // C++17
319    int compare(size_type pos1, size_type n1, const basic_string& str,
320                size_type pos2, size_type n2=npos) const; // C++14
321    template <class T>
322        int compare(size_type pos1, size_type n1, const T& t,
323                    size_type pos2, size_type n2=npos) const; // C++17
324    int compare(const value_type* s) const noexcept;
325    int compare(size_type pos1, size_type n1, const value_type* s) const;
326    int compare(size_type pos1, size_type n1, const value_type* s, size_type n2) const;
327
328    bool starts_with(basic_string_view<charT, traits> sv) const noexcept; // C++20
329    bool starts_with(charT c) const noexcept;                             // C++20
330    bool starts_with(const charT* s) const;                               // C++20
331    bool ends_with(basic_string_view<charT, traits> sv) const noexcept;   // C++20
332    bool ends_with(charT c) const noexcept;                               // C++20
333    bool ends_with(const charT* s) const;                                 // C++20
334
335    constexpr bool contains(basic_string_view<charT, traits> sv) const noexcept; // C++2b
336    constexpr bool contains(charT c) const noexcept;                             // C++2b
337    constexpr bool contains(const charT* s) const;                               // C++2b
338
339    bool __invariants() const;
340};
341
342template<class InputIterator,
343         class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
344basic_string(InputIterator, InputIterator, Allocator = Allocator())
345   -> basic_string<typename iterator_traits<InputIterator>::value_type,
346                  char_traits<typename iterator_traits<InputIterator>::value_type>,
347                  Allocator>;   // C++17
348
349template<class charT, class traits, class Allocator>
350basic_string<charT, traits, Allocator>
351operator+(const basic_string<charT, traits, Allocator>& lhs,
352          const basic_string<charT, traits, Allocator>& rhs);
353
354template<class charT, class traits, class Allocator>
355basic_string<charT, traits, Allocator>
356operator+(const charT* lhs , const basic_string<charT,traits,Allocator>&rhs);
357
358template<class charT, class traits, class Allocator>
359basic_string<charT, traits, Allocator>
360operator+(charT lhs, const basic_string<charT,traits,Allocator>& rhs);
361
362template<class charT, class traits, class Allocator>
363basic_string<charT, traits, Allocator>
364operator+(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs);
365
366template<class charT, class traits, class Allocator>
367basic_string<charT, traits, Allocator>
368operator+(const basic_string<charT, traits, Allocator>& lhs, charT rhs);
369
370template<class charT, class traits, class Allocator>
371bool operator==(const basic_string<charT, traits, Allocator>& lhs,
372                const basic_string<charT, traits, Allocator>& rhs) noexcept;
373
374template<class charT, class traits, class Allocator>
375bool operator==(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
376
377template<class charT, class traits, class Allocator>
378bool operator==(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs) noexcept;
379
380template<class charT, class traits, class Allocator>
381bool operator!=(const basic_string<charT,traits,Allocator>& lhs,
382                const basic_string<charT, traits, Allocator>& rhs) noexcept;
383
384template<class charT, class traits, class Allocator>
385bool operator!=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
386
387template<class charT, class traits, class Allocator>
388bool operator!=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
389
390template<class charT, class traits, class Allocator>
391bool operator< (const basic_string<charT, traits, Allocator>& lhs,
392                const basic_string<charT, traits, Allocator>& rhs) noexcept;
393
394template<class charT, class traits, class Allocator>
395bool operator< (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
396
397template<class charT, class traits, class Allocator>
398bool operator< (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
399
400template<class charT, class traits, class Allocator>
401bool operator> (const basic_string<charT, traits, Allocator>& lhs,
402                const basic_string<charT, traits, Allocator>& rhs) noexcept;
403
404template<class charT, class traits, class Allocator>
405bool operator> (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
406
407template<class charT, class traits, class Allocator>
408bool operator> (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
409
410template<class charT, class traits, class Allocator>
411bool operator<=(const basic_string<charT, traits, Allocator>& lhs,
412                const basic_string<charT, traits, Allocator>& rhs) noexcept;
413
414template<class charT, class traits, class Allocator>
415bool operator<=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
416
417template<class charT, class traits, class Allocator>
418bool operator<=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
419
420template<class charT, class traits, class Allocator>
421bool operator>=(const basic_string<charT, traits, Allocator>& lhs,
422                const basic_string<charT, traits, Allocator>& rhs) noexcept;
423
424template<class charT, class traits, class Allocator>
425bool operator>=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
426
427template<class charT, class traits, class Allocator>
428bool operator>=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
429
430template<class charT, class traits, class Allocator>
431void swap(basic_string<charT, traits, Allocator>& lhs,
432          basic_string<charT, traits, Allocator>& rhs)
433            noexcept(noexcept(lhs.swap(rhs)));
434
435template<class charT, class traits, class Allocator>
436basic_istream<charT, traits>&
437operator>>(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);
438
439template<class charT, class traits, class Allocator>
440basic_ostream<charT, traits>&
441operator<<(basic_ostream<charT, traits>& os, const basic_string<charT, traits, Allocator>& str);
442
443template<class charT, class traits, class Allocator>
444basic_istream<charT, traits>&
445getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str,
446        charT delim);
447
448template<class charT, class traits, class Allocator>
449basic_istream<charT, traits>&
450getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);
451
452template<class charT, class traits, class Allocator, class U>
453typename basic_string<charT, traits, Allocator>::size_type
454erase(basic_string<charT, traits, Allocator>& c, const U& value);    // C++20
455template<class charT, class traits, class Allocator, class Predicate>
456typename basic_string<charT, traits, Allocator>::size_type
457erase_if(basic_string<charT, traits, Allocator>& c, Predicate pred); // C++20
458
459typedef basic_string<char>    string;
460typedef basic_string<wchar_t> wstring;
461typedef basic_string<char8_t> u8string; // C++20
462typedef basic_string<char16_t> u16string;
463typedef basic_string<char32_t> u32string;
464
465int                stoi  (const string& str, size_t* idx = nullptr, int base = 10);
466long               stol  (const string& str, size_t* idx = nullptr, int base = 10);
467unsigned long      stoul (const string& str, size_t* idx = nullptr, int base = 10);
468long long          stoll (const string& str, size_t* idx = nullptr, int base = 10);
469unsigned long long stoull(const string& str, size_t* idx = nullptr, int base = 10);
470
471float       stof (const string& str, size_t* idx = nullptr);
472double      stod (const string& str, size_t* idx = nullptr);
473long double stold(const string& str, size_t* idx = nullptr);
474
475string to_string(int val);
476string to_string(unsigned val);
477string to_string(long val);
478string to_string(unsigned long val);
479string to_string(long long val);
480string to_string(unsigned long long val);
481string to_string(float val);
482string to_string(double val);
483string to_string(long double val);
484
485int                stoi  (const wstring& str, size_t* idx = nullptr, int base = 10);
486long               stol  (const wstring& str, size_t* idx = nullptr, int base = 10);
487unsigned long      stoul (const wstring& str, size_t* idx = nullptr, int base = 10);
488long long          stoll (const wstring& str, size_t* idx = nullptr, int base = 10);
489unsigned long long stoull(const wstring& str, size_t* idx = nullptr, int base = 10);
490
491float       stof (const wstring& str, size_t* idx = nullptr);
492double      stod (const wstring& str, size_t* idx = nullptr);
493long double stold(const wstring& str, size_t* idx = nullptr);
494
495wstring to_wstring(int val);
496wstring to_wstring(unsigned val);
497wstring to_wstring(long val);
498wstring to_wstring(unsigned long val);
499wstring to_wstring(long long val);
500wstring to_wstring(unsigned long long val);
501wstring to_wstring(float val);
502wstring to_wstring(double val);
503wstring to_wstring(long double val);
504
505template <> struct hash<string>;
506template <> struct hash<u8string>; // C++20
507template <> struct hash<u16string>;
508template <> struct hash<u32string>;
509template <> struct hash<wstring>;
510
511basic_string<char>     operator "" s( const char *str,     size_t len ); // C++14
512basic_string<wchar_t>  operator "" s( const wchar_t *str,  size_t len ); // C++14
513basic_string<char8_t>  operator "" s( const char8_t *str,  size_t len ); // C++20
514basic_string<char16_t> operator "" s( const char16_t *str, size_t len ); // C++14
515basic_string<char32_t> operator "" s( const char32_t *str, size_t len ); // C++14
516
517}  // std
518
519*/
520
521#include <__config>
522#include <__debug>
523#include <__functional_base>
524#include <__iterator/wrap_iter.h>
525#include <algorithm>
526#include <compare>
527#include <cstdio>  // EOF
528#include <cstdlib>
529#include <cstring>
530#include <initializer_list>
531#include <iosfwd>
532#include <iterator>
533#include <memory>
534#include <stdexcept>
535#include <string_view>
536#include <type_traits>
537#include <utility>
538#include <version>
539
540#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
541#   include <cwchar>
542#endif
543
544#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
545# include <cstdint>
546#endif
547
548#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
549#pragma GCC system_header
550#endif
551
552_LIBCPP_PUSH_MACROS
553#include <__undef_macros>
554
555
556_LIBCPP_BEGIN_NAMESPACE_STD
557
558// fpos
559
560template <class _StateT>
561class _LIBCPP_TEMPLATE_VIS fpos
562{
563private:
564    _StateT __st_;
565    streamoff __off_;
566public:
567    _LIBCPP_INLINE_VISIBILITY fpos(streamoff __off = streamoff()) : __st_(), __off_(__off) {}
568
569    _LIBCPP_INLINE_VISIBILITY operator streamoff() const {return __off_;}
570
571    _LIBCPP_INLINE_VISIBILITY _StateT state() const {return __st_;}
572    _LIBCPP_INLINE_VISIBILITY void state(_StateT __st) {__st_ = __st;}
573
574    _LIBCPP_INLINE_VISIBILITY fpos& operator+=(streamoff __off) {__off_ += __off; return *this;}
575    _LIBCPP_INLINE_VISIBILITY fpos  operator+ (streamoff __off) const {fpos __t(*this); __t += __off; return __t;}
576    _LIBCPP_INLINE_VISIBILITY fpos& operator-=(streamoff __off) {__off_ -= __off; return *this;}
577    _LIBCPP_INLINE_VISIBILITY fpos  operator- (streamoff __off) const {fpos __t(*this); __t -= __off; return __t;}
578};
579
580template <class _StateT>
581inline _LIBCPP_INLINE_VISIBILITY
582streamoff operator-(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
583    {return streamoff(__x) - streamoff(__y);}
584
585template <class _StateT>
586inline _LIBCPP_INLINE_VISIBILITY
587bool operator==(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
588    {return streamoff(__x) == streamoff(__y);}
589
590template <class _StateT>
591inline _LIBCPP_INLINE_VISIBILITY
592bool operator!=(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
593    {return streamoff(__x) != streamoff(__y);}
594
595// basic_string
596
597template<class _CharT, class _Traits, class _Allocator>
598basic_string<_CharT, _Traits, _Allocator>
599operator+(const basic_string<_CharT, _Traits, _Allocator>& __x,
600          const basic_string<_CharT, _Traits, _Allocator>& __y);
601
602template<class _CharT, class _Traits, class _Allocator>
603basic_string<_CharT, _Traits, _Allocator>
604operator+(const _CharT* __x, const basic_string<_CharT,_Traits,_Allocator>& __y);
605
606template<class _CharT, class _Traits, class _Allocator>
607basic_string<_CharT, _Traits, _Allocator>
608operator+(_CharT __x, const basic_string<_CharT,_Traits,_Allocator>& __y);
609
610template<class _CharT, class _Traits, class _Allocator>
611inline _LIBCPP_INLINE_VISIBILITY
612basic_string<_CharT, _Traits, _Allocator>
613operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, const _CharT* __y);
614
615template<class _CharT, class _Traits, class _Allocator>
616basic_string<_CharT, _Traits, _Allocator>
617operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, _CharT __y);
618
619_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS string operator+<char, char_traits<char>, allocator<char> >(char const*, string const&))
620
621template <bool>
622struct __basic_string_common;
623
624template <>
625struct __basic_string_common<true> {
626    // Both are defined in string.cpp
627    _LIBCPP_NORETURN _LIBCPP_EXPORTED_FROM_ABI void __throw_length_error() const;
628    _LIBCPP_NORETURN _LIBCPP_EXPORTED_FROM_ABI void __throw_out_of_range() const;
629};
630
631template <class _Iter>
632struct __string_is_trivial_iterator : public false_type {};
633
634template <class _Tp>
635struct __string_is_trivial_iterator<_Tp*>
636    : public is_arithmetic<_Tp> {};
637
638template <class _Iter>
639struct __string_is_trivial_iterator<__wrap_iter<_Iter> >
640    : public __string_is_trivial_iterator<_Iter> {};
641
642template <class _CharT, class _Traits, class _Tp>
643struct __can_be_converted_to_string_view : public _BoolConstant<
644      is_convertible<const _Tp&, basic_string_view<_CharT, _Traits> >::value &&
645     !is_convertible<const _Tp&, const _CharT*>::value
646    > {};
647
648#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
649
650template <class _CharT, size_t = sizeof(_CharT)>
651struct __padding
652{
653    unsigned char __xx[sizeof(_CharT)-1];
654};
655
656template <class _CharT>
657struct __padding<_CharT, 1>
658{
659};
660
661#endif // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
662
663#ifndef _LIBCPP_HAS_NO_CHAR8_T
664typedef basic_string<char8_t> u8string;
665#endif
666
667#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
668typedef basic_string<char16_t> u16string;
669typedef basic_string<char32_t> u32string;
670#endif
671
672template<class _CharT, class _Traits, class _Allocator>
673class
674    _LIBCPP_TEMPLATE_VIS
675#ifndef _LIBCPP_HAS_NO_CHAR8_T
676    _LIBCPP_PREFERRED_NAME(u8string)
677#endif
678#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
679    _LIBCPP_PREFERRED_NAME(u16string)
680    _LIBCPP_PREFERRED_NAME(u32string)
681#endif
682    basic_string
683    : private __basic_string_common<true> // This base class is historical, but it needs to remain for ABI compatibility
684{
685public:
686    typedef basic_string                                 __self;
687    typedef basic_string_view<_CharT, _Traits>           __self_view;
688    typedef _Traits                                      traits_type;
689    typedef _CharT                                       value_type;
690    typedef _Allocator                                   allocator_type;
691    typedef allocator_traits<allocator_type>             __alloc_traits;
692    typedef typename __alloc_traits::size_type           size_type;
693    typedef typename __alloc_traits::difference_type     difference_type;
694    typedef value_type&                                  reference;
695    typedef const value_type&                            const_reference;
696    typedef typename __alloc_traits::pointer             pointer;
697    typedef typename __alloc_traits::const_pointer       const_pointer;
698
699    static_assert((!is_array<value_type>::value), "Character type of basic_string must not be an array");
700    static_assert(( is_standard_layout<value_type>::value), "Character type of basic_string must be standard-layout");
701    static_assert(( is_trivial<value_type>::value), "Character type of basic_string must be trivial");
702    static_assert(( is_same<_CharT, typename traits_type::char_type>::value),
703                  "traits_type::char_type must be the same type as CharT");
704    static_assert(( is_same<typename allocator_type::value_type, value_type>::value),
705                  "Allocator::value_type must be same type as value_type");
706
707    typedef __wrap_iter<pointer>                         iterator;
708    typedef __wrap_iter<const_pointer>                   const_iterator;
709    typedef _VSTD::reverse_iterator<iterator>             reverse_iterator;
710    typedef _VSTD::reverse_iterator<const_iterator>       const_reverse_iterator;
711
712private:
713
714#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
715
716    struct __long
717    {
718        pointer   __data_;
719        size_type __size_;
720        size_type __cap_;
721    };
722
723#ifdef _LIBCPP_BIG_ENDIAN
724    static const size_type __short_mask = 0x01;
725    static const size_type __long_mask  = 0x1ul;
726#else  // _LIBCPP_BIG_ENDIAN
727    static const size_type __short_mask = 0x80;
728    static const size_type __long_mask  = ~(size_type(~0) >> 1);
729#endif // _LIBCPP_BIG_ENDIAN
730
731    enum {__min_cap = (sizeof(__long) - 1)/sizeof(value_type) > 2 ?
732                      (sizeof(__long) - 1)/sizeof(value_type) : 2};
733
734    struct __short
735    {
736        value_type __data_[__min_cap];
737        struct
738            : __padding<value_type>
739        {
740            unsigned char __size_;
741        };
742    };
743
744#else
745
746    struct __long
747    {
748        size_type __cap_;
749        size_type __size_;
750        pointer   __data_;
751    };
752
753#ifdef _LIBCPP_BIG_ENDIAN
754    static const size_type __short_mask = 0x80;
755    static const size_type __long_mask  = ~(size_type(~0) >> 1);
756#else  // _LIBCPP_BIG_ENDIAN
757    static const size_type __short_mask = 0x01;
758    static const size_type __long_mask  = 0x1ul;
759#endif // _LIBCPP_BIG_ENDIAN
760
761    enum {__min_cap = (sizeof(__long) - 1)/sizeof(value_type) > 2 ?
762                      (sizeof(__long) - 1)/sizeof(value_type) : 2};
763
764    struct __short
765    {
766        union
767        {
768            unsigned char __size_;
769            value_type __lx;
770        };
771        value_type __data_[__min_cap];
772    };
773
774#endif // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
775
776    union __ulx{__long __lx; __short __lxx;};
777
778    enum {__n_words = sizeof(__ulx) / sizeof(size_type)};
779
780    struct __raw
781    {
782        size_type __words[__n_words];
783    };
784
785    struct __rep
786    {
787        union
788        {
789            __long  __l;
790            __short __s;
791            __raw   __r;
792        };
793    };
794
795    __compressed_pair<__rep, allocator_type> __r_;
796
797public:
798    _LIBCPP_TEMPLATE_DATA_VIS
799    static const size_type npos = -1;
800
801    _LIBCPP_INLINE_VISIBILITY basic_string()
802        _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
803
804    _LIBCPP_INLINE_VISIBILITY explicit basic_string(const allocator_type& __a)
805#if _LIBCPP_STD_VER <= 14
806        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value);
807#else
808        _NOEXCEPT;
809#endif
810
811    basic_string(const basic_string& __str);
812    basic_string(const basic_string& __str, const allocator_type& __a);
813
814#ifndef _LIBCPP_CXX03_LANG
815    _LIBCPP_INLINE_VISIBILITY
816    basic_string(basic_string&& __str)
817#if _LIBCPP_STD_VER <= 14
818        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
819#else
820        _NOEXCEPT;
821#endif
822
823    _LIBCPP_INLINE_VISIBILITY
824    basic_string(basic_string&& __str, const allocator_type& __a);
825#endif // _LIBCPP_CXX03_LANG
826
827    template <class = __enable_if_t<__is_allocator<_Allocator>::value, nullptr_t> >
828    _LIBCPP_INLINE_VISIBILITY
829    basic_string(const _CharT* __s) : __r_(__default_init_tag(), __default_init_tag()) {
830      _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*) detected nullptr");
831      __init(__s, traits_type::length(__s));
832      _VSTD::__debug_db_insert_c(this);
833    }
834
835    template <class = __enable_if_t<__is_allocator<_Allocator>::value, nullptr_t> >
836        _LIBCPP_INLINE_VISIBILITY
837        basic_string(const _CharT* __s, const _Allocator& __a);
838
839#if _LIBCPP_STD_VER > 20
840    basic_string(nullptr_t) = delete;
841#endif
842
843    _LIBCPP_INLINE_VISIBILITY
844    basic_string(const _CharT* __s, size_type __n);
845    _LIBCPP_INLINE_VISIBILITY
846    basic_string(const _CharT* __s, size_type __n, const _Allocator& __a);
847    _LIBCPP_INLINE_VISIBILITY
848    basic_string(size_type __n, _CharT __c);
849
850    template <class = __enable_if_t<__is_allocator<_Allocator>::value, nullptr_t> >
851        _LIBCPP_INLINE_VISIBILITY
852        basic_string(size_type __n, _CharT __c, const _Allocator& __a);
853
854    basic_string(const basic_string& __str, size_type __pos, size_type __n,
855                 const _Allocator& __a = _Allocator());
856    _LIBCPP_INLINE_VISIBILITY
857    basic_string(const basic_string& __str, size_type __pos,
858                 const _Allocator& __a = _Allocator());
859
860    template<class _Tp, class = __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
861        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
862        basic_string(const _Tp& __t, size_type __pos, size_type __n,
863                     const allocator_type& __a = allocator_type());
864
865    template<class _Tp, class = __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
866                                          !__is_same_uncvref<_Tp, basic_string>::value> >
867        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
868        explicit basic_string(const _Tp& __t);
869
870    template<class _Tp, class = __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
871        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
872        explicit basic_string(const _Tp& __t, const allocator_type& __a);
873
874    template<class _InputIterator, class = __enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value> >
875        _LIBCPP_INLINE_VISIBILITY
876        basic_string(_InputIterator __first, _InputIterator __last);
877    template<class _InputIterator, class = __enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value> >
878        _LIBCPP_INLINE_VISIBILITY
879        basic_string(_InputIterator __first, _InputIterator __last, const allocator_type& __a);
880#ifndef _LIBCPP_CXX03_LANG
881    _LIBCPP_INLINE_VISIBILITY
882    basic_string(initializer_list<_CharT> __il);
883    _LIBCPP_INLINE_VISIBILITY
884    basic_string(initializer_list<_CharT> __il, const _Allocator& __a);
885#endif // _LIBCPP_CXX03_LANG
886
887    inline ~basic_string();
888
889    _LIBCPP_INLINE_VISIBILITY
890    operator __self_view() const _NOEXCEPT { return __self_view(data(), size()); }
891
892    basic_string& operator=(const basic_string& __str);
893
894    template <class _Tp, class = __enable_if_t<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
895    basic_string& operator=(const _Tp& __t)
896        {__self_view __sv = __t; return assign(__sv);}
897
898#ifndef _LIBCPP_CXX03_LANG
899    _LIBCPP_INLINE_VISIBILITY
900    basic_string& operator=(basic_string&& __str)
901        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value));
902     _LIBCPP_INLINE_VISIBILITY
903    basic_string& operator=(initializer_list<value_type> __il) {return assign(__il.begin(), __il.size());}
904#endif
905    _LIBCPP_INLINE_VISIBILITY basic_string& operator=(const value_type* __s) {return assign(__s);}
906#if _LIBCPP_STD_VER > 20
907    basic_string& operator=(nullptr_t) = delete;
908#endif
909    basic_string& operator=(value_type __c);
910
911#if _LIBCPP_DEBUG_LEVEL == 2
912    _LIBCPP_INLINE_VISIBILITY
913    iterator begin() _NOEXCEPT
914        {return iterator(this, __get_pointer());}
915    _LIBCPP_INLINE_VISIBILITY
916    const_iterator begin() const _NOEXCEPT
917        {return const_iterator(this, __get_pointer());}
918    _LIBCPP_INLINE_VISIBILITY
919    iterator end() _NOEXCEPT
920        {return iterator(this, __get_pointer() + size());}
921    _LIBCPP_INLINE_VISIBILITY
922    const_iterator end() const _NOEXCEPT
923        {return const_iterator(this, __get_pointer() + size());}
924#else
925    _LIBCPP_INLINE_VISIBILITY
926    iterator begin() _NOEXCEPT
927        {return iterator(__get_pointer());}
928    _LIBCPP_INLINE_VISIBILITY
929    const_iterator begin() const _NOEXCEPT
930        {return const_iterator(__get_pointer());}
931    _LIBCPP_INLINE_VISIBILITY
932    iterator end() _NOEXCEPT
933        {return iterator(__get_pointer() + size());}
934    _LIBCPP_INLINE_VISIBILITY
935    const_iterator end() const _NOEXCEPT
936        {return const_iterator(__get_pointer() + size());}
937#endif // _LIBCPP_DEBUG_LEVEL == 2
938    _LIBCPP_INLINE_VISIBILITY
939    reverse_iterator rbegin() _NOEXCEPT
940        {return reverse_iterator(end());}
941    _LIBCPP_INLINE_VISIBILITY
942    const_reverse_iterator rbegin() const _NOEXCEPT
943        {return const_reverse_iterator(end());}
944    _LIBCPP_INLINE_VISIBILITY
945    reverse_iterator rend() _NOEXCEPT
946        {return reverse_iterator(begin());}
947    _LIBCPP_INLINE_VISIBILITY
948    const_reverse_iterator rend() const _NOEXCEPT
949        {return const_reverse_iterator(begin());}
950
951    _LIBCPP_INLINE_VISIBILITY
952    const_iterator cbegin() const _NOEXCEPT
953        {return begin();}
954    _LIBCPP_INLINE_VISIBILITY
955    const_iterator cend() const _NOEXCEPT
956        {return end();}
957    _LIBCPP_INLINE_VISIBILITY
958    const_reverse_iterator crbegin() const _NOEXCEPT
959        {return rbegin();}
960    _LIBCPP_INLINE_VISIBILITY
961    const_reverse_iterator crend() const _NOEXCEPT
962        {return rend();}
963
964    _LIBCPP_INLINE_VISIBILITY size_type size() const _NOEXCEPT
965        {return __is_long() ? __get_long_size() : __get_short_size();}
966    _LIBCPP_INLINE_VISIBILITY size_type length() const _NOEXCEPT {return size();}
967    _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT;
968    _LIBCPP_INLINE_VISIBILITY size_type capacity() const _NOEXCEPT
969        {return (__is_long() ? __get_long_cap()
970                             : static_cast<size_type>(__min_cap)) - 1;}
971
972    void resize(size_type __n, value_type __c);
973    _LIBCPP_INLINE_VISIBILITY void resize(size_type __n) {resize(__n, value_type());}
974
975    void reserve(size_type __requested_capacity);
976
977#if _LIBCPP_STD_VER > 20
978    template <class _Op>
979    _LIBCPP_HIDE_FROM_ABI constexpr
980    void resize_and_overwrite(size_type __n, _Op __op) {
981      __resize_default_init(__n);
982      __erase_to_end(_VSTD::move(__op)(data(), _LIBCPP_AUTO_CAST(__n)));
983    }
984#endif
985
986    _LIBCPP_INLINE_VISIBILITY void __resize_default_init(size_type __n);
987
988    _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_INLINE_VISIBILITY
989    void reserve() _NOEXCEPT {shrink_to_fit();}
990    _LIBCPP_INLINE_VISIBILITY
991    void shrink_to_fit() _NOEXCEPT;
992    _LIBCPP_INLINE_VISIBILITY
993    void clear() _NOEXCEPT;
994    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
995    bool empty() const _NOEXCEPT {return size() == 0;}
996
997    _LIBCPP_INLINE_VISIBILITY const_reference operator[](size_type __pos) const _NOEXCEPT;
998    _LIBCPP_INLINE_VISIBILITY reference       operator[](size_type __pos)       _NOEXCEPT;
999
1000    const_reference at(size_type __n) const;
1001    reference       at(size_type __n);
1002
1003    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const basic_string& __str) {return append(__str);}
1004
1005    template <class _Tp>
1006    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1007    __enable_if_t
1008        <
1009            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1010            && !__is_same_uncvref<_Tp, basic_string >::value,
1011            basic_string&
1012        >
1013                                            operator+=(const _Tp& __t)            {__self_view __sv = __t; return append(__sv);}
1014    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const value_type* __s)     {return append(__s);}
1015    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(value_type __c)            {push_back(__c); return *this;}
1016#ifndef _LIBCPP_CXX03_LANG
1017    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(initializer_list<value_type> __il) {return append(__il);}
1018#endif // _LIBCPP_CXX03_LANG
1019
1020    _LIBCPP_INLINE_VISIBILITY
1021    basic_string& append(const basic_string& __str);
1022
1023    template <class _Tp>
1024    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1025    __enable_if_t<
1026            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1027            && !__is_same_uncvref<_Tp, basic_string>::value,
1028            basic_string&
1029        >
1030                  append(const _Tp& __t) { __self_view __sv = __t; return append(__sv.data(), __sv.size()); }
1031    basic_string& append(const basic_string& __str, size_type __pos, size_type __n=npos);
1032
1033    template <class _Tp>
1034    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1035    __enable_if_t
1036        <
1037            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1038            && !__is_same_uncvref<_Tp, basic_string>::value,
1039            basic_string&
1040        >
1041                  append(const _Tp& __t, size_type __pos, size_type __n=npos);
1042    basic_string& append(const value_type* __s, size_type __n);
1043    basic_string& append(const value_type* __s);
1044    basic_string& append(size_type __n, value_type __c);
1045
1046    _LIBCPP_INLINE_VISIBILITY
1047    void __append_default_init(size_type __n);
1048
1049    template<class _InputIterator>
1050    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1051    __enable_if_t
1052        <
1053            __is_exactly_cpp17_input_iterator<_InputIterator>::value,
1054            basic_string&
1055        >
1056    _LIBCPP_INLINE_VISIBILITY
1057    append(_InputIterator __first, _InputIterator __last) {
1058      const basic_string __temp(__first, __last, __alloc());
1059      append(__temp.data(), __temp.size());
1060      return *this;
1061    }
1062    template<class _ForwardIterator>
1063    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1064    __enable_if_t
1065        <
1066            __is_cpp17_forward_iterator<_ForwardIterator>::value,
1067            basic_string&
1068        >
1069    _LIBCPP_INLINE_VISIBILITY
1070    append(_ForwardIterator __first, _ForwardIterator __last);
1071
1072#ifndef _LIBCPP_CXX03_LANG
1073    _LIBCPP_INLINE_VISIBILITY
1074    basic_string& append(initializer_list<value_type> __il) {return append(__il.begin(), __il.size());}
1075#endif // _LIBCPP_CXX03_LANG
1076
1077    void push_back(value_type __c);
1078    _LIBCPP_INLINE_VISIBILITY
1079    void pop_back();
1080    _LIBCPP_INLINE_VISIBILITY reference       front() _NOEXCEPT;
1081    _LIBCPP_INLINE_VISIBILITY const_reference front() const _NOEXCEPT;
1082    _LIBCPP_INLINE_VISIBILITY reference       back() _NOEXCEPT;
1083    _LIBCPP_INLINE_VISIBILITY const_reference back() const _NOEXCEPT;
1084
1085    template <class _Tp>
1086    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1087    __enable_if_t
1088        <
1089            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1090            basic_string&
1091        >
1092                 assign(const _Tp & __t) { __self_view __sv = __t; return assign(__sv.data(), __sv.size()); }
1093    _LIBCPP_INLINE_VISIBILITY
1094    basic_string& assign(const basic_string& __str) { return *this = __str; }
1095#ifndef _LIBCPP_CXX03_LANG
1096    _LIBCPP_INLINE_VISIBILITY
1097    basic_string& assign(basic_string&& __str)
1098        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
1099        {*this = _VSTD::move(__str); return *this;}
1100#endif
1101    basic_string& assign(const basic_string& __str, size_type __pos, size_type __n=npos);
1102    template <class _Tp>
1103    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1104    __enable_if_t
1105        <
1106            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1107            && !__is_same_uncvref<_Tp, basic_string>::value,
1108            basic_string&
1109        >
1110                  assign(const _Tp & __t, size_type __pos, size_type __n=npos);
1111    basic_string& assign(const value_type* __s, size_type __n);
1112    basic_string& assign(const value_type* __s);
1113    basic_string& assign(size_type __n, value_type __c);
1114    template<class _InputIterator>
1115    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1116    __enable_if_t
1117        <
1118            __is_exactly_cpp17_input_iterator<_InputIterator>::value,
1119            basic_string&
1120        >
1121        assign(_InputIterator __first, _InputIterator __last);
1122    template<class _ForwardIterator>
1123    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1124    __enable_if_t
1125        <
1126            __is_cpp17_forward_iterator<_ForwardIterator>::value,
1127            basic_string&
1128        >
1129        assign(_ForwardIterator __first, _ForwardIterator __last);
1130#ifndef _LIBCPP_CXX03_LANG
1131    _LIBCPP_INLINE_VISIBILITY
1132    basic_string& assign(initializer_list<value_type> __il) {return assign(__il.begin(), __il.size());}
1133#endif // _LIBCPP_CXX03_LANG
1134
1135    _LIBCPP_INLINE_VISIBILITY
1136    basic_string& insert(size_type __pos1, const basic_string& __str);
1137
1138    template <class _Tp>
1139    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1140    __enable_if_t
1141        <
1142            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1143            basic_string&
1144        >
1145                 insert(size_type __pos1, const _Tp& __t)
1146    { __self_view __sv = __t; return insert(__pos1, __sv.data(), __sv.size()); }
1147
1148    template <class _Tp>
1149    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1150    __enable_if_t
1151        <
1152            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value,
1153            basic_string&
1154        >
1155                  insert(size_type __pos1, const _Tp& __t, size_type __pos2, size_type __n=npos);
1156    basic_string& insert(size_type __pos1, const basic_string& __str, size_type __pos2, size_type __n=npos);
1157    basic_string& insert(size_type __pos, const value_type* __s, size_type __n);
1158    basic_string& insert(size_type __pos, const value_type* __s);
1159    basic_string& insert(size_type __pos, size_type __n, value_type __c);
1160    iterator      insert(const_iterator __pos, value_type __c);
1161    _LIBCPP_INLINE_VISIBILITY
1162    iterator      insert(const_iterator __pos, size_type __n, value_type __c);
1163    template<class _InputIterator>
1164    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1165    __enable_if_t
1166        <
1167            __is_exactly_cpp17_input_iterator<_InputIterator>::value,
1168            iterator
1169        >
1170        insert(const_iterator __pos, _InputIterator __first, _InputIterator __last);
1171    template<class _ForwardIterator>
1172    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1173    __enable_if_t
1174        <
1175            __is_cpp17_forward_iterator<_ForwardIterator>::value,
1176            iterator
1177        >
1178        insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last);
1179#ifndef _LIBCPP_CXX03_LANG
1180    _LIBCPP_INLINE_VISIBILITY
1181    iterator insert(const_iterator __pos, initializer_list<value_type> __il)
1182                    {return insert(__pos, __il.begin(), __il.end());}
1183#endif // _LIBCPP_CXX03_LANG
1184
1185    basic_string& erase(size_type __pos = 0, size_type __n = npos);
1186    _LIBCPP_INLINE_VISIBILITY
1187    iterator      erase(const_iterator __pos);
1188    _LIBCPP_INLINE_VISIBILITY
1189    iterator      erase(const_iterator __first, const_iterator __last);
1190
1191    _LIBCPP_INLINE_VISIBILITY
1192    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str);
1193
1194    template <class _Tp>
1195    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1196    __enable_if_t
1197        <
1198            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1199            basic_string&
1200        >
1201                  replace(size_type __pos1, size_type __n1, const _Tp& __t) { __self_view __sv = __t; return replace(__pos1, __n1, __sv.data(), __sv.size()); }
1202    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos);
1203    template <class _Tp>
1204    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1205    __enable_if_t
1206        <
1207            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
1208            basic_string&
1209        >
1210                  replace(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos);
1211    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2);
1212    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s);
1213    basic_string& replace(size_type __pos, size_type __n1, size_type __n2, value_type __c);
1214    _LIBCPP_INLINE_VISIBILITY
1215    basic_string& replace(const_iterator __i1, const_iterator __i2, const basic_string& __str);
1216
1217    template <class _Tp>
1218    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1219    __enable_if_t
1220        <
1221            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1222            basic_string&
1223        >
1224                  replace(const_iterator __i1, const_iterator __i2, const _Tp& __t) { __self_view __sv = __t; return replace(__i1 - begin(), __i2 - __i1, __sv); }
1225
1226    _LIBCPP_INLINE_VISIBILITY
1227    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n);
1228    _LIBCPP_INLINE_VISIBILITY
1229    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s);
1230    _LIBCPP_INLINE_VISIBILITY
1231    basic_string& replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c);
1232    template<class _InputIterator>
1233    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1234    __enable_if_t
1235        <
1236            __is_cpp17_input_iterator<_InputIterator>::value,
1237            basic_string&
1238        >
1239        replace(const_iterator __i1, const_iterator __i2, _InputIterator __j1, _InputIterator __j2);
1240#ifndef _LIBCPP_CXX03_LANG
1241    _LIBCPP_INLINE_VISIBILITY
1242    basic_string& replace(const_iterator __i1, const_iterator __i2, initializer_list<value_type> __il)
1243        {return replace(__i1, __i2, __il.begin(), __il.end());}
1244#endif // _LIBCPP_CXX03_LANG
1245
1246    size_type copy(value_type* __s, size_type __n, size_type __pos = 0) const;
1247    _LIBCPP_INLINE_VISIBILITY
1248    basic_string substr(size_type __pos = 0, size_type __n = npos) const;
1249
1250    _LIBCPP_INLINE_VISIBILITY
1251    void swap(basic_string& __str)
1252#if _LIBCPP_STD_VER >= 14
1253        _NOEXCEPT;
1254#else
1255        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
1256                    __is_nothrow_swappable<allocator_type>::value);
1257#endif
1258
1259    _LIBCPP_INLINE_VISIBILITY
1260    const value_type* c_str() const _NOEXCEPT {return data();}
1261    _LIBCPP_INLINE_VISIBILITY
1262    const value_type* data() const _NOEXCEPT  {return _VSTD::__to_address(__get_pointer());}
1263#if _LIBCPP_STD_VER > 14 || defined(_LIBCPP_BUILDING_LIBRARY)
1264    _LIBCPP_INLINE_VISIBILITY
1265    value_type* data()             _NOEXCEPT  {return _VSTD::__to_address(__get_pointer());}
1266#endif
1267
1268    _LIBCPP_INLINE_VISIBILITY
1269    allocator_type get_allocator() const _NOEXCEPT {return __alloc();}
1270
1271    _LIBCPP_INLINE_VISIBILITY
1272    size_type find(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1273
1274    template <class _Tp>
1275    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1276    __enable_if_t
1277        <
1278            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1279            size_type
1280        >
1281              find(const _Tp& __t, size_type __pos = 0) const _NOEXCEPT;
1282    size_type find(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1283    _LIBCPP_INLINE_VISIBILITY
1284    size_type find(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1285    size_type find(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1286
1287    _LIBCPP_INLINE_VISIBILITY
1288    size_type rfind(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1289
1290    template <class _Tp>
1291    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1292    __enable_if_t
1293        <
1294            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1295            size_type
1296        >
1297              rfind(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1298    size_type rfind(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1299    _LIBCPP_INLINE_VISIBILITY
1300    size_type rfind(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1301    size_type rfind(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1302
1303    _LIBCPP_INLINE_VISIBILITY
1304    size_type find_first_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1305
1306    template <class _Tp>
1307    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1308    __enable_if_t
1309        <
1310            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1311            size_type
1312        >
1313              find_first_of(const _Tp& __t, size_type __pos = 0) const _NOEXCEPT;
1314    size_type find_first_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1315    _LIBCPP_INLINE_VISIBILITY
1316    size_type find_first_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1317    _LIBCPP_INLINE_VISIBILITY
1318    size_type find_first_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1319
1320    _LIBCPP_INLINE_VISIBILITY
1321    size_type find_last_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1322
1323    template <class _Tp>
1324    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1325    __enable_if_t
1326        <
1327            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1328            size_type
1329        >
1330              find_last_of(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1331    size_type find_last_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1332    _LIBCPP_INLINE_VISIBILITY
1333    size_type find_last_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1334    _LIBCPP_INLINE_VISIBILITY
1335    size_type find_last_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1336
1337    _LIBCPP_INLINE_VISIBILITY
1338    size_type find_first_not_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1339
1340    template <class _Tp>
1341    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1342    __enable_if_t
1343        <
1344            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1345            size_type
1346        >
1347              find_first_not_of(const _Tp &__t, size_type __pos = 0) const _NOEXCEPT;
1348    size_type find_first_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1349    _LIBCPP_INLINE_VISIBILITY
1350    size_type find_first_not_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1351    _LIBCPP_INLINE_VISIBILITY
1352    size_type find_first_not_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1353
1354    _LIBCPP_INLINE_VISIBILITY
1355    size_type find_last_not_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1356
1357    template <class _Tp>
1358    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1359    __enable_if_t
1360        <
1361            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1362            size_type
1363        >
1364              find_last_not_of(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1365    size_type find_last_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1366    _LIBCPP_INLINE_VISIBILITY
1367    size_type find_last_not_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1368    _LIBCPP_INLINE_VISIBILITY
1369    size_type find_last_not_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1370
1371    _LIBCPP_INLINE_VISIBILITY
1372    int compare(const basic_string& __str) const _NOEXCEPT;
1373
1374    template <class _Tp>
1375    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1376    __enable_if_t
1377        <
1378            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1379            int
1380        >
1381        compare(const _Tp &__t) const _NOEXCEPT;
1382
1383    template <class _Tp>
1384    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1385    __enable_if_t
1386        <
1387            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1388            int
1389        >
1390         compare(size_type __pos1, size_type __n1, const _Tp& __t) const;
1391
1392    _LIBCPP_INLINE_VISIBILITY
1393    int compare(size_type __pos1, size_type __n1, const basic_string& __str) const;
1394    int compare(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos) const;
1395
1396    template <class _Tp>
1397    inline _LIBCPP_INLINE_VISIBILITY
1398        __enable_if_t
1399        <
1400            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
1401            int
1402        >
1403        compare(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos) const;
1404    int compare(const value_type* __s) const _NOEXCEPT;
1405    int compare(size_type __pos1, size_type __n1, const value_type* __s) const;
1406    int compare(size_type __pos1, size_type __n1, const value_type* __s, size_type __n2) const;
1407
1408#if _LIBCPP_STD_VER > 17
1409    constexpr _LIBCPP_INLINE_VISIBILITY
1410    bool starts_with(__self_view __sv) const noexcept
1411    { return __self_view(data(), size()).starts_with(__sv); }
1412
1413    constexpr _LIBCPP_INLINE_VISIBILITY
1414    bool starts_with(value_type __c) const noexcept
1415    { return !empty() && _Traits::eq(front(), __c); }
1416
1417    constexpr _LIBCPP_INLINE_VISIBILITY
1418    bool starts_with(const value_type* __s) const noexcept
1419    { return starts_with(__self_view(__s)); }
1420
1421    constexpr _LIBCPP_INLINE_VISIBILITY
1422    bool ends_with(__self_view __sv) const noexcept
1423    { return __self_view(data(), size()).ends_with( __sv); }
1424
1425    constexpr _LIBCPP_INLINE_VISIBILITY
1426    bool ends_with(value_type __c) const noexcept
1427    { return !empty() && _Traits::eq(back(), __c); }
1428
1429    constexpr _LIBCPP_INLINE_VISIBILITY
1430    bool ends_with(const value_type* __s) const noexcept
1431    { return ends_with(__self_view(__s)); }
1432#endif
1433
1434#if _LIBCPP_STD_VER > 20
1435    constexpr _LIBCPP_INLINE_VISIBILITY
1436    bool contains(__self_view __sv) const noexcept
1437    { return __self_view(data(), size()).contains(__sv); }
1438
1439    constexpr _LIBCPP_INLINE_VISIBILITY
1440    bool contains(value_type __c) const noexcept
1441    { return __self_view(data(), size()).contains(__c); }
1442
1443    constexpr _LIBCPP_INLINE_VISIBILITY
1444    bool contains(const value_type* __s) const
1445    { return __self_view(data(), size()).contains(__s); }
1446#endif
1447
1448    _LIBCPP_INLINE_VISIBILITY bool __invariants() const;
1449
1450    _LIBCPP_INLINE_VISIBILITY void __clear_and_shrink() _NOEXCEPT;
1451
1452    _LIBCPP_INLINE_VISIBILITY void __shrink_or_extend(size_type __target_capacity);
1453
1454    _LIBCPP_INLINE_VISIBILITY
1455    bool __is_long() const _NOEXCEPT
1456        {return bool(__r_.first().__s.__size_ & __short_mask);}
1457
1458#if _LIBCPP_DEBUG_LEVEL == 2
1459
1460    bool __dereferenceable(const const_iterator* __i) const;
1461    bool __decrementable(const const_iterator* __i) const;
1462    bool __addable(const const_iterator* __i, ptrdiff_t __n) const;
1463    bool __subscriptable(const const_iterator* __i, ptrdiff_t __n) const;
1464
1465#endif // _LIBCPP_DEBUG_LEVEL == 2
1466
1467private:
1468    _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI static bool __fits_in_sso(size_type __sz) {
1469        // SSO is disabled during constant evaluation because `__is_long` isn't constexpr friendly
1470        return !__libcpp_is_constant_evaluated() && (__sz < __min_cap);
1471    }
1472
1473    _LIBCPP_INLINE_VISIBILITY
1474    allocator_type& __alloc() _NOEXCEPT
1475        {return __r_.second();}
1476    _LIBCPP_INLINE_VISIBILITY
1477    const allocator_type& __alloc() const _NOEXCEPT
1478        {return __r_.second();}
1479
1480#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1481
1482    _LIBCPP_INLINE_VISIBILITY
1483    void __set_short_size(size_type __s) _NOEXCEPT
1484#   ifdef _LIBCPP_BIG_ENDIAN
1485        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
1486#   else
1487        {__r_.first().__s.__size_ = (unsigned char)(__s);}
1488#   endif
1489
1490    _LIBCPP_INLINE_VISIBILITY
1491    size_type __get_short_size() const _NOEXCEPT
1492#   ifdef _LIBCPP_BIG_ENDIAN
1493        {return __r_.first().__s.__size_ >> 1;}
1494#   else
1495        {return __r_.first().__s.__size_;}
1496#   endif
1497
1498#else  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1499
1500    _LIBCPP_INLINE_VISIBILITY
1501    void __set_short_size(size_type __s) _NOEXCEPT
1502#   ifdef _LIBCPP_BIG_ENDIAN
1503        {__r_.first().__s.__size_ = (unsigned char)(__s);}
1504#   else
1505        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
1506#   endif
1507
1508    _LIBCPP_INLINE_VISIBILITY
1509    size_type __get_short_size() const _NOEXCEPT
1510#   ifdef _LIBCPP_BIG_ENDIAN
1511        {return __r_.first().__s.__size_;}
1512#   else
1513        {return __r_.first().__s.__size_ >> 1;}
1514#   endif
1515
1516#endif // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1517
1518    _LIBCPP_INLINE_VISIBILITY
1519    void __set_long_size(size_type __s) _NOEXCEPT
1520        {__r_.first().__l.__size_ = __s;}
1521    _LIBCPP_INLINE_VISIBILITY
1522    size_type __get_long_size() const _NOEXCEPT
1523        {return __r_.first().__l.__size_;}
1524    _LIBCPP_INLINE_VISIBILITY
1525    void __set_size(size_type __s) _NOEXCEPT
1526        {if (__is_long()) __set_long_size(__s); else __set_short_size(__s);}
1527
1528    _LIBCPP_INLINE_VISIBILITY
1529    void __set_long_cap(size_type __s) _NOEXCEPT
1530        {__r_.first().__l.__cap_  = __long_mask | __s;}
1531    _LIBCPP_INLINE_VISIBILITY
1532    size_type __get_long_cap() const _NOEXCEPT
1533        {return __r_.first().__l.__cap_ & size_type(~__long_mask);}
1534
1535    _LIBCPP_INLINE_VISIBILITY
1536    void __set_long_pointer(pointer __p) _NOEXCEPT
1537        {__r_.first().__l.__data_ = __p;}
1538    _LIBCPP_INLINE_VISIBILITY
1539    pointer __get_long_pointer() _NOEXCEPT
1540        {return __r_.first().__l.__data_;}
1541    _LIBCPP_INLINE_VISIBILITY
1542    const_pointer __get_long_pointer() const _NOEXCEPT
1543        {return __r_.first().__l.__data_;}
1544    _LIBCPP_INLINE_VISIBILITY
1545    pointer __get_short_pointer() _NOEXCEPT
1546        {return pointer_traits<pointer>::pointer_to(__r_.first().__s.__data_[0]);}
1547    _LIBCPP_INLINE_VISIBILITY
1548    const_pointer __get_short_pointer() const _NOEXCEPT
1549        {return pointer_traits<const_pointer>::pointer_to(__r_.first().__s.__data_[0]);}
1550    _LIBCPP_INLINE_VISIBILITY
1551    pointer __get_pointer() _NOEXCEPT
1552        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
1553    _LIBCPP_INLINE_VISIBILITY
1554    const_pointer __get_pointer() const _NOEXCEPT
1555        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
1556
1557    _LIBCPP_INLINE_VISIBILITY
1558    void __zero() _NOEXCEPT
1559        {
1560            size_type (&__a)[__n_words] = __r_.first().__r.__words;
1561            for (unsigned __i = 0; __i < __n_words; ++__i)
1562                __a[__i] = 0;
1563        }
1564
1565    template <size_type __a> static
1566        _LIBCPP_INLINE_VISIBILITY
1567        size_type __align_it(size_type __s) _NOEXCEPT
1568            {return (__s + (__a-1)) & ~(__a-1);}
1569    enum {__alignment = 16};
1570    static _LIBCPP_INLINE_VISIBILITY
1571    size_type __recommend(size_type __s) _NOEXCEPT
1572        {
1573        if (__s < __min_cap) return static_cast<size_type>(__min_cap) - 1;
1574        size_type __guess = __align_it<sizeof(value_type) < __alignment ?
1575                     __alignment/sizeof(value_type) : 1 > (__s+1) - 1;
1576        if (__guess == __min_cap) ++__guess;
1577        return __guess;
1578        }
1579
1580    inline
1581    void __init(const value_type* __s, size_type __sz, size_type __reserve);
1582    inline
1583    void __init(const value_type* __s, size_type __sz);
1584    inline
1585    void __init(size_type __n, value_type __c);
1586
1587    // Slow path for the (inlined) copy constructor for 'long' strings.
1588    // Always externally instantiated and not inlined.
1589    // Requires that __s is zero terminated.
1590    // The main reason for this function to exist is because for unstable, we
1591    // want to allow inlining of the copy constructor. However, we don't want
1592    // to call the __init() functions as those are marked as inline which may
1593    // result in over-aggressive inlining by the compiler, where our aim is
1594    // to only inline the fast path code directly in the ctor.
1595    void __init_copy_ctor_external(const value_type* __s, size_type __sz);
1596
1597    template <class _InputIterator>
1598    inline
1599    __enable_if_t
1600    <
1601        __is_exactly_cpp17_input_iterator<_InputIterator>::value
1602    >
1603    __init(_InputIterator __first, _InputIterator __last);
1604
1605    template <class _ForwardIterator>
1606    inline
1607    __enable_if_t
1608    <
1609        __is_cpp17_forward_iterator<_ForwardIterator>::value
1610    >
1611    __init(_ForwardIterator __first, _ForwardIterator __last);
1612
1613    void __grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1614                   size_type __n_copy,  size_type __n_del,     size_type __n_add = 0);
1615    void __grow_by_and_replace(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1616                               size_type __n_copy,  size_type __n_del,
1617                               size_type __n_add, const value_type* __p_new_stuff);
1618
1619    // __assign_no_alias is invoked for assignment operations where we
1620    // have proof that the input does not alias the current instance.
1621    // For example, operator=(basic_string) performs a 'self' check.
1622    template <bool __is_short>
1623    basic_string& __assign_no_alias(const value_type* __s, size_type __n);
1624
1625    _LIBCPP_INLINE_VISIBILITY
1626    void __erase_to_end(size_type __pos);
1627
1628    // __erase_external_with_move is invoked for erase() invocations where
1629    // `n ~= npos`, likely requiring memory moves on the string data.
1630    void __erase_external_with_move(size_type __pos, size_type __n);
1631
1632    _LIBCPP_INLINE_VISIBILITY
1633    void __copy_assign_alloc(const basic_string& __str)
1634        {__copy_assign_alloc(__str, integral_constant<bool,
1635                      __alloc_traits::propagate_on_container_copy_assignment::value>());}
1636
1637    _LIBCPP_INLINE_VISIBILITY
1638    void __copy_assign_alloc(const basic_string& __str, true_type)
1639        {
1640            if (__alloc() == __str.__alloc())
1641                __alloc() = __str.__alloc();
1642            else
1643            {
1644                if (!__str.__is_long())
1645                {
1646                    __clear_and_shrink();
1647                    __alloc() = __str.__alloc();
1648                }
1649                else
1650                {
1651                    allocator_type __a = __str.__alloc();
1652                    pointer __p = __alloc_traits::allocate(__a, __str.__get_long_cap());
1653                    __clear_and_shrink();
1654                    __alloc() = _VSTD::move(__a);
1655                    __set_long_pointer(__p);
1656                    __set_long_cap(__str.__get_long_cap());
1657                    __set_long_size(__str.size());
1658                }
1659            }
1660        }
1661
1662    _LIBCPP_INLINE_VISIBILITY
1663    void __copy_assign_alloc(const basic_string&, false_type) _NOEXCEPT
1664        {}
1665
1666#ifndef _LIBCPP_CXX03_LANG
1667    _LIBCPP_INLINE_VISIBILITY
1668    void __move_assign(basic_string& __str, false_type)
1669        _NOEXCEPT_(__alloc_traits::is_always_equal::value);
1670    _LIBCPP_INLINE_VISIBILITY
1671    void __move_assign(basic_string& __str, true_type)
1672#if _LIBCPP_STD_VER > 14
1673        _NOEXCEPT;
1674#else
1675        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
1676#endif
1677#endif
1678
1679    _LIBCPP_INLINE_VISIBILITY
1680    void
1681    __move_assign_alloc(basic_string& __str)
1682        _NOEXCEPT_(
1683            !__alloc_traits::propagate_on_container_move_assignment::value ||
1684            is_nothrow_move_assignable<allocator_type>::value)
1685    {__move_assign_alloc(__str, integral_constant<bool,
1686                      __alloc_traits::propagate_on_container_move_assignment::value>());}
1687
1688    _LIBCPP_INLINE_VISIBILITY
1689    void __move_assign_alloc(basic_string& __c, true_type)
1690        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
1691        {
1692            __alloc() = _VSTD::move(__c.__alloc());
1693        }
1694
1695    _LIBCPP_INLINE_VISIBILITY
1696    void __move_assign_alloc(basic_string&, false_type)
1697        _NOEXCEPT
1698        {}
1699
1700    basic_string& __assign_external(const value_type* __s);
1701    basic_string& __assign_external(const value_type* __s, size_type __n);
1702
1703    // Assigns the value in __s, guaranteed to be __n < __min_cap in length.
1704    inline basic_string& __assign_short(const value_type* __s, size_type __n) {
1705      pointer __p = __is_long()
1706                        ? (__set_long_size(__n), __get_long_pointer())
1707                        : (__set_short_size(__n), __get_short_pointer());
1708      traits_type::move(_VSTD::__to_address(__p), __s, __n);
1709      traits_type::assign(__p[__n], value_type());
1710      return *this;
1711    }
1712
1713    _LIBCPP_HIDE_FROM_ABI basic_string& __null_terminate_at(value_type* __p, size_type __newsz) {
1714      __set_size(__newsz);
1715      __invalidate_iterators_past(__newsz);
1716      traits_type::assign(__p[__newsz], value_type());
1717      return *this;
1718    }
1719
1720    _LIBCPP_INLINE_VISIBILITY void __invalidate_all_iterators();
1721    _LIBCPP_INLINE_VISIBILITY void __invalidate_iterators_past(size_type);
1722
1723    template<class _Tp>
1724    _LIBCPP_INLINE_VISIBILITY
1725    bool __addr_in_range(_Tp&& __t) const {
1726        const volatile void *__p = _VSTD::addressof(__t);
1727        return data() <= __p && __p <= data() + size();
1728    }
1729
1730    _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI
1731    void __throw_length_error() const {
1732#ifndef _LIBCPP_NO_EXCEPTIONS
1733        __basic_string_common<true>::__throw_length_error();
1734#else
1735        _VSTD::abort();
1736#endif
1737    }
1738
1739    _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI
1740    void __throw_out_of_range() const {
1741#ifndef _LIBCPP_NO_EXCEPTIONS
1742        __basic_string_common<true>::__throw_out_of_range();
1743#else
1744        _VSTD::abort();
1745#endif
1746    }
1747
1748    friend basic_string operator+<>(const basic_string&, const basic_string&);
1749    friend basic_string operator+<>(const value_type*, const basic_string&);
1750    friend basic_string operator+<>(value_type, const basic_string&);
1751    friend basic_string operator+<>(const basic_string&, const value_type*);
1752    friend basic_string operator+<>(const basic_string&, value_type);
1753};
1754
1755// These declarations must appear before any functions are implicitly used
1756// so that they have the correct visibility specifier.
1757#ifdef _LIBCPP_ABI_STRING_OPTIMIZED_EXTERNAL_INSTANTIATION
1758    _LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
1759#   ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
1760        _LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
1761#   endif
1762#else
1763    _LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
1764#   ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
1765        _LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
1766#   endif
1767#endif
1768
1769
1770#if _LIBCPP_STD_VER >= 17
1771template<class _InputIterator,
1772         class _CharT = __iter_value_type<_InputIterator>,
1773         class _Allocator = allocator<_CharT>,
1774         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
1775         class = enable_if_t<__is_allocator<_Allocator>::value>
1776         >
1777basic_string(_InputIterator, _InputIterator, _Allocator = _Allocator())
1778  -> basic_string<_CharT, char_traits<_CharT>, _Allocator>;
1779
1780template<class _CharT,
1781         class _Traits,
1782         class _Allocator = allocator<_CharT>,
1783         class = enable_if_t<__is_allocator<_Allocator>::value>
1784         >
1785explicit basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
1786  -> basic_string<_CharT, _Traits, _Allocator>;
1787
1788template<class _CharT,
1789         class _Traits,
1790         class _Allocator = allocator<_CharT>,
1791         class = enable_if_t<__is_allocator<_Allocator>::value>,
1792         class _Sz = typename allocator_traits<_Allocator>::size_type
1793         >
1794basic_string(basic_string_view<_CharT, _Traits>, _Sz, _Sz, const _Allocator& = _Allocator())
1795  -> basic_string<_CharT, _Traits, _Allocator>;
1796#endif
1797
1798template <class _CharT, class _Traits, class _Allocator>
1799inline
1800void
1801basic_string<_CharT, _Traits, _Allocator>::__invalidate_all_iterators()
1802{
1803#if _LIBCPP_DEBUG_LEVEL == 2
1804    if (!__libcpp_is_constant_evaluated())
1805        __get_db()->__invalidate_all(this);
1806#endif
1807}
1808
1809template <class _CharT, class _Traits, class _Allocator>
1810inline
1811void
1812basic_string<_CharT, _Traits, _Allocator>::__invalidate_iterators_past(size_type __pos)
1813{
1814#if _LIBCPP_DEBUG_LEVEL == 2
1815    if (!__libcpp_is_constant_evaluated()) {
1816        __c_node* __c = __get_db()->__find_c_and_lock(this);
1817        if (__c)
1818        {
1819            const_pointer __new_last = __get_pointer() + __pos;
1820            for (__i_node** __p = __c->end_; __p != __c->beg_; )
1821            {
1822                --__p;
1823                const_iterator* __i = static_cast<const_iterator*>((*__p)->__i_);
1824                if (__i->base() > __new_last)
1825                {
1826                    (*__p)->__c_ = nullptr;
1827                    if (--__c->end_ != __p)
1828                        _VSTD::memmove(__p, __p+1, (__c->end_ - __p)*sizeof(__i_node*));
1829                }
1830            }
1831            __get_db()->unlock();
1832        }
1833    }
1834#else
1835    (void)__pos;
1836#endif // _LIBCPP_DEBUG_LEVEL == 2
1837}
1838
1839template <class _CharT, class _Traits, class _Allocator>
1840inline
1841basic_string<_CharT, _Traits, _Allocator>::basic_string()
1842    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
1843     : __r_(__default_init_tag(), __default_init_tag())
1844{
1845    _VSTD::__debug_db_insert_c(this);
1846    __zero();
1847}
1848
1849template <class _CharT, class _Traits, class _Allocator>
1850inline
1851basic_string<_CharT, _Traits, _Allocator>::basic_string(const allocator_type& __a)
1852#if _LIBCPP_STD_VER <= 14
1853        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value)
1854#else
1855        _NOEXCEPT
1856#endif
1857: __r_(__default_init_tag(), __a)
1858{
1859    _VSTD::__debug_db_insert_c(this);
1860    __zero();
1861}
1862
1863template <class _CharT, class _Traits, class _Allocator>
1864void basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s,
1865                                                       size_type __sz,
1866                                                       size_type __reserve)
1867{
1868    if (__reserve > max_size())
1869        this->__throw_length_error();
1870    pointer __p;
1871    if (__fits_in_sso(__reserve))
1872    {
1873        __set_short_size(__sz);
1874        __p = __get_short_pointer();
1875    }
1876    else
1877    {
1878        size_type __cap = __recommend(__reserve);
1879        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1880        __set_long_pointer(__p);
1881        __set_long_cap(__cap+1);
1882        __set_long_size(__sz);
1883    }
1884    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1885    traits_type::assign(__p[__sz], value_type());
1886}
1887
1888template <class _CharT, class _Traits, class _Allocator>
1889void
1890basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s, size_type __sz)
1891{
1892    if (__sz > max_size())
1893        this->__throw_length_error();
1894    pointer __p;
1895    if (__fits_in_sso(__sz))
1896    {
1897        __set_short_size(__sz);
1898        __p = __get_short_pointer();
1899    }
1900    else
1901    {
1902        size_type __cap = __recommend(__sz);
1903        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1904        __set_long_pointer(__p);
1905        __set_long_cap(__cap+1);
1906        __set_long_size(__sz);
1907    }
1908    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1909    traits_type::assign(__p[__sz], value_type());
1910}
1911
1912template <class _CharT, class _Traits, class _Allocator>
1913template <class>
1914basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, const _Allocator& __a)
1915    : __r_(__default_init_tag(), __a)
1916{
1917    _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*, allocator) detected nullptr");
1918    __init(__s, traits_type::length(__s));
1919    _VSTD::__debug_db_insert_c(this);
1920}
1921
1922template <class _CharT, class _Traits, class _Allocator>
1923inline
1924basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n)
1925     : __r_(__default_init_tag(), __default_init_tag())
1926{
1927    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n) detected nullptr");
1928    __init(__s, __n);
1929    _VSTD::__debug_db_insert_c(this);
1930}
1931
1932template <class _CharT, class _Traits, class _Allocator>
1933inline
1934basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n, const _Allocator& __a)
1935    : __r_(__default_init_tag(), __a)
1936{
1937    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n, allocator) detected nullptr");
1938    __init(__s, __n);
1939    _VSTD::__debug_db_insert_c(this);
1940}
1941
1942template <class _CharT, class _Traits, class _Allocator>
1943basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str)
1944    : __r_(__default_init_tag(), __alloc_traits::select_on_container_copy_construction(__str.__alloc()))
1945{
1946    if (!__str.__is_long())
1947        __r_.first().__r = __str.__r_.first().__r;
1948    else
1949        __init_copy_ctor_external(_VSTD::__to_address(__str.__get_long_pointer()),
1950                                  __str.__get_long_size());
1951    _VSTD::__debug_db_insert_c(this);
1952}
1953
1954template <class _CharT, class _Traits, class _Allocator>
1955basic_string<_CharT, _Traits, _Allocator>::basic_string(
1956    const basic_string& __str, const allocator_type& __a)
1957    : __r_(__default_init_tag(), __a)
1958{
1959    if (!__str.__is_long())
1960        __r_.first().__r = __str.__r_.first().__r;
1961    else
1962        __init_copy_ctor_external(_VSTD::__to_address(__str.__get_long_pointer()),
1963                                  __str.__get_long_size());
1964    _VSTD::__debug_db_insert_c(this);
1965}
1966
1967template <class _CharT, class _Traits, class _Allocator>
1968void basic_string<_CharT, _Traits, _Allocator>::__init_copy_ctor_external(
1969    const value_type* __s, size_type __sz) {
1970  pointer __p;
1971  if (__fits_in_sso(__sz)) {
1972    __p = __get_short_pointer();
1973    __set_short_size(__sz);
1974  } else {
1975    if (__sz > max_size())
1976      this->__throw_length_error();
1977    size_t __cap = __recommend(__sz);
1978    __p = __alloc_traits::allocate(__alloc(), __cap + 1);
1979    __set_long_pointer(__p);
1980    __set_long_cap(__cap + 1);
1981    __set_long_size(__sz);
1982  }
1983  traits_type::copy(_VSTD::__to_address(__p), __s, __sz + 1);
1984}
1985
1986#ifndef _LIBCPP_CXX03_LANG
1987
1988template <class _CharT, class _Traits, class _Allocator>
1989inline
1990basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str)
1991#if _LIBCPP_STD_VER <= 14
1992        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
1993#else
1994        _NOEXCEPT
1995#endif
1996    : __r_(_VSTD::move(__str.__r_))
1997{
1998    __str.__zero();
1999    _VSTD::__debug_db_insert_c(this);
2000#if _LIBCPP_DEBUG_LEVEL == 2
2001    if (!__libcpp_is_constant_evaluated() && __is_long())
2002        __get_db()->swap(this, &__str);
2003#endif
2004}
2005
2006template <class _CharT, class _Traits, class _Allocator>
2007inline
2008basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str, const allocator_type& __a)
2009    : __r_(__default_init_tag(), __a)
2010{
2011    if (__str.__is_long() && __a != __str.__alloc()) // copy, not move
2012        __init(_VSTD::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
2013    else
2014    {
2015        __r_.first().__r = __str.__r_.first().__r;
2016        __str.__zero();
2017    }
2018    _VSTD::__debug_db_insert_c(this);
2019#if _LIBCPP_DEBUG_LEVEL == 2
2020    if (!__libcpp_is_constant_evaluated() && __is_long())
2021        __get_db()->swap(this, &__str);
2022#endif
2023}
2024
2025#endif // _LIBCPP_CXX03_LANG
2026
2027template <class _CharT, class _Traits, class _Allocator>
2028void
2029basic_string<_CharT, _Traits, _Allocator>::__init(size_type __n, value_type __c)
2030{
2031    if (__n > max_size())
2032        this->__throw_length_error();
2033    pointer __p;
2034    if (__fits_in_sso(__n))
2035    {
2036        __set_short_size(__n);
2037        __p = __get_short_pointer();
2038    }
2039    else
2040    {
2041        size_type __cap = __recommend(__n);
2042        __p = __alloc_traits::allocate(__alloc(), __cap+1);
2043        __set_long_pointer(__p);
2044        __set_long_cap(__cap+1);
2045        __set_long_size(__n);
2046    }
2047    traits_type::assign(_VSTD::__to_address(__p), __n, __c);
2048    traits_type::assign(__p[__n], value_type());
2049}
2050
2051template <class _CharT, class _Traits, class _Allocator>
2052inline
2053basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c)
2054     : __r_(__default_init_tag(), __default_init_tag())
2055{
2056    __init(__n, __c);
2057    _VSTD::__debug_db_insert_c(this);
2058}
2059
2060template <class _CharT, class _Traits, class _Allocator>
2061template <class>
2062basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c, const _Allocator& __a)
2063    : __r_(__default_init_tag(), __a)
2064{
2065    __init(__n, __c);
2066    _VSTD::__debug_db_insert_c(this);
2067}
2068
2069template <class _CharT, class _Traits, class _Allocator>
2070basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str,
2071                                                        size_type __pos, size_type __n,
2072                                                        const _Allocator& __a)
2073    : __r_(__default_init_tag(), __a)
2074{
2075    size_type __str_sz = __str.size();
2076    if (__pos > __str_sz)
2077        this->__throw_out_of_range();
2078    __init(__str.data() + __pos, _VSTD::min(__n, __str_sz - __pos));
2079    _VSTD::__debug_db_insert_c(this);
2080}
2081
2082template <class _CharT, class _Traits, class _Allocator>
2083inline
2084basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str, size_type __pos,
2085                                                        const _Allocator& __a)
2086    : __r_(__default_init_tag(), __a)
2087{
2088    size_type __str_sz = __str.size();
2089    if (__pos > __str_sz)
2090        this->__throw_out_of_range();
2091    __init(__str.data() + __pos, __str_sz - __pos);
2092    _VSTD::__debug_db_insert_c(this);
2093}
2094
2095template <class _CharT, class _Traits, class _Allocator>
2096template <class _Tp, class>
2097basic_string<_CharT, _Traits, _Allocator>::basic_string(
2098             const _Tp& __t, size_type __pos, size_type __n, const allocator_type& __a)
2099    : __r_(__default_init_tag(), __a)
2100{
2101    __self_view __sv0 = __t;
2102    __self_view __sv = __sv0.substr(__pos, __n);
2103    __init(__sv.data(), __sv.size());
2104    _VSTD::__debug_db_insert_c(this);
2105}
2106
2107template <class _CharT, class _Traits, class _Allocator>
2108template <class _Tp, class>
2109basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t)
2110     : __r_(__default_init_tag(), __default_init_tag())
2111{
2112    __self_view __sv = __t;
2113    __init(__sv.data(), __sv.size());
2114    _VSTD::__debug_db_insert_c(this);
2115}
2116
2117template <class _CharT, class _Traits, class _Allocator>
2118template <class _Tp, class>
2119basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t, const _Allocator& __a)
2120    : __r_(__default_init_tag(), __a)
2121{
2122    __self_view __sv = __t;
2123    __init(__sv.data(), __sv.size());
2124    _VSTD::__debug_db_insert_c(this);
2125}
2126
2127template <class _CharT, class _Traits, class _Allocator>
2128template <class _InputIterator>
2129__enable_if_t
2130<
2131    __is_exactly_cpp17_input_iterator<_InputIterator>::value
2132>
2133basic_string<_CharT, _Traits, _Allocator>::__init(_InputIterator __first, _InputIterator __last)
2134{
2135    __zero();
2136#ifndef _LIBCPP_NO_EXCEPTIONS
2137    try
2138    {
2139#endif // _LIBCPP_NO_EXCEPTIONS
2140    for (; __first != __last; ++__first)
2141        push_back(*__first);
2142#ifndef _LIBCPP_NO_EXCEPTIONS
2143    }
2144    catch (...)
2145    {
2146        if (__is_long())
2147            __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2148        throw;
2149    }
2150#endif // _LIBCPP_NO_EXCEPTIONS
2151}
2152
2153template <class _CharT, class _Traits, class _Allocator>
2154template <class _ForwardIterator>
2155__enable_if_t
2156<
2157    __is_cpp17_forward_iterator<_ForwardIterator>::value
2158>
2159basic_string<_CharT, _Traits, _Allocator>::__init(_ForwardIterator __first, _ForwardIterator __last)
2160{
2161    size_type __sz = static_cast<size_type>(_VSTD::distance(__first, __last));
2162    if (__sz > max_size())
2163        this->__throw_length_error();
2164    pointer __p;
2165    if (__fits_in_sso(__sz))
2166    {
2167        __set_short_size(__sz);
2168        __p = __get_short_pointer();
2169    }
2170    else
2171    {
2172        size_type __cap = __recommend(__sz);
2173        __p = __alloc_traits::allocate(__alloc(), __cap+1);
2174        __set_long_pointer(__p);
2175        __set_long_cap(__cap+1);
2176        __set_long_size(__sz);
2177    }
2178
2179#ifndef _LIBCPP_NO_EXCEPTIONS
2180    try
2181    {
2182#endif  // _LIBCPP_NO_EXCEPTIONS
2183    for (; __first != __last; ++__first, (void) ++__p)
2184        traits_type::assign(*__p, *__first);
2185    traits_type::assign(*__p, value_type());
2186#ifndef _LIBCPP_NO_EXCEPTIONS
2187    }
2188    catch (...)
2189    {
2190        if (__is_long())
2191            __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2192        throw;
2193    }
2194#endif  // _LIBCPP_NO_EXCEPTIONS
2195}
2196
2197template <class _CharT, class _Traits, class _Allocator>
2198template<class _InputIterator, class>
2199inline
2200basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last)
2201     : __r_(__default_init_tag(), __default_init_tag())
2202{
2203    __init(__first, __last);
2204    _VSTD::__debug_db_insert_c(this);
2205}
2206
2207template <class _CharT, class _Traits, class _Allocator>
2208template<class _InputIterator, class>
2209inline
2210basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last,
2211                                                        const allocator_type& __a)
2212    : __r_(__default_init_tag(), __a)
2213{
2214    __init(__first, __last);
2215    _VSTD::__debug_db_insert_c(this);
2216}
2217
2218#ifndef _LIBCPP_CXX03_LANG
2219
2220template <class _CharT, class _Traits, class _Allocator>
2221inline
2222basic_string<_CharT, _Traits, _Allocator>::basic_string(
2223    initializer_list<_CharT> __il)
2224     : __r_(__default_init_tag(), __default_init_tag())
2225{
2226    __init(__il.begin(), __il.end());
2227    _VSTD::__debug_db_insert_c(this);
2228}
2229
2230template <class _CharT, class _Traits, class _Allocator>
2231inline
2232
2233basic_string<_CharT, _Traits, _Allocator>::basic_string(
2234    initializer_list<_CharT> __il, const _Allocator& __a)
2235    : __r_(__default_init_tag(), __a)
2236{
2237    __init(__il.begin(), __il.end());
2238    _VSTD::__debug_db_insert_c(this);
2239}
2240
2241#endif // _LIBCPP_CXX03_LANG
2242
2243template <class _CharT, class _Traits, class _Allocator>
2244basic_string<_CharT, _Traits, _Allocator>::~basic_string()
2245{
2246#if _LIBCPP_DEBUG_LEVEL == 2
2247    if (!__libcpp_is_constant_evaluated())
2248        __get_db()->__erase_c(this);
2249#endif
2250    if (__is_long())
2251        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2252}
2253
2254template <class _CharT, class _Traits, class _Allocator>
2255void
2256basic_string<_CharT, _Traits, _Allocator>::__grow_by_and_replace
2257    (size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2258     size_type __n_copy,  size_type __n_del,     size_type __n_add, const value_type* __p_new_stuff)
2259{
2260    size_type __ms = max_size();
2261    if (__delta_cap > __ms - __old_cap - 1)
2262        this->__throw_length_error();
2263    pointer __old_p = __get_pointer();
2264    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2265                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2266                          __ms - 1;
2267    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2268    __invalidate_all_iterators();
2269    if (__n_copy != 0)
2270        traits_type::copy(_VSTD::__to_address(__p),
2271                          _VSTD::__to_address(__old_p), __n_copy);
2272    if (__n_add != 0)
2273        traits_type::copy(_VSTD::__to_address(__p) + __n_copy, __p_new_stuff, __n_add);
2274    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2275    if (__sec_cp_sz != 0)
2276        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2277                          _VSTD::__to_address(__old_p) + __n_copy + __n_del, __sec_cp_sz);
2278    if (__old_cap+1 != __min_cap)
2279        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2280    __set_long_pointer(__p);
2281    __set_long_cap(__cap+1);
2282    __old_sz = __n_copy + __n_add + __sec_cp_sz;
2283    __set_long_size(__old_sz);
2284    traits_type::assign(__p[__old_sz], value_type());
2285}
2286
2287template <class _CharT, class _Traits, class _Allocator>
2288void
2289basic_string<_CharT, _Traits, _Allocator>::__grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2290                                                     size_type __n_copy,  size_type __n_del,     size_type __n_add)
2291{
2292    size_type __ms = max_size();
2293    if (__delta_cap > __ms - __old_cap)
2294        this->__throw_length_error();
2295    pointer __old_p = __get_pointer();
2296    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2297                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2298                          __ms - 1;
2299    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2300    __invalidate_all_iterators();
2301    if (__n_copy != 0)
2302        traits_type::copy(_VSTD::__to_address(__p),
2303                          _VSTD::__to_address(__old_p), __n_copy);
2304    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2305    if (__sec_cp_sz != 0)
2306        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2307                          _VSTD::__to_address(__old_p) + __n_copy + __n_del,
2308                          __sec_cp_sz);
2309    if (__old_cap+1 != __min_cap)
2310        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2311    __set_long_pointer(__p);
2312    __set_long_cap(__cap+1);
2313}
2314
2315// assign
2316
2317template <class _CharT, class _Traits, class _Allocator>
2318template <bool __is_short>
2319basic_string<_CharT, _Traits, _Allocator>&
2320basic_string<_CharT, _Traits, _Allocator>::__assign_no_alias(
2321    const value_type* __s, size_type __n) {
2322  size_type __cap = __is_short ? __min_cap : __get_long_cap();
2323  if (__n < __cap) {
2324    pointer __p = __is_short ? __get_short_pointer() : __get_long_pointer();
2325    __is_short ? __set_short_size(__n) : __set_long_size(__n);
2326    traits_type::copy(_VSTD::__to_address(__p), __s, __n);
2327    traits_type::assign(__p[__n], value_type());
2328    __invalidate_iterators_past(__n);
2329  } else {
2330    size_type __sz = __is_short ? __get_short_size() : __get_long_size();
2331    __grow_by_and_replace(__cap - 1, __n - __cap + 1, __sz, 0, __sz, __n, __s);
2332  }
2333  return *this;
2334}
2335
2336template <class _CharT, class _Traits, class _Allocator>
2337basic_string<_CharT, _Traits, _Allocator>&
2338basic_string<_CharT, _Traits, _Allocator>::__assign_external(
2339    const value_type* __s, size_type __n) {
2340  size_type __cap = capacity();
2341  if (__cap >= __n) {
2342    value_type* __p = _VSTD::__to_address(__get_pointer());
2343    traits_type::move(__p, __s, __n);
2344    return __null_terminate_at(__p, __n);
2345  } else {
2346    size_type __sz = size();
2347    __grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s);
2348    return *this;
2349  }
2350}
2351
2352template <class _CharT, class _Traits, class _Allocator>
2353basic_string<_CharT, _Traits, _Allocator>&
2354basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s, size_type __n)
2355{
2356    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::assign received nullptr");
2357    return (__builtin_constant_p(__n) && __fits_in_sso(__n))
2358               ? __assign_short(__s, __n)
2359               : __assign_external(__s, __n);
2360}
2361
2362template <class _CharT, class _Traits, class _Allocator>
2363basic_string<_CharT, _Traits, _Allocator>&
2364basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
2365{
2366    size_type __cap = capacity();
2367    if (__cap < __n)
2368    {
2369        size_type __sz = size();
2370        __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2371    }
2372    value_type* __p = _VSTD::__to_address(__get_pointer());
2373    traits_type::assign(__p, __n, __c);
2374    return __null_terminate_at(__p, __n);
2375}
2376
2377template <class _CharT, class _Traits, class _Allocator>
2378basic_string<_CharT, _Traits, _Allocator>&
2379basic_string<_CharT, _Traits, _Allocator>::operator=(value_type __c)
2380{
2381    pointer __p;
2382    if (__is_long())
2383    {
2384        __p = __get_long_pointer();
2385        __set_long_size(1);
2386    }
2387    else
2388    {
2389        __p = __get_short_pointer();
2390        __set_short_size(1);
2391    }
2392    traits_type::assign(*__p, __c);
2393    traits_type::assign(*++__p, value_type());
2394    __invalidate_iterators_past(1);
2395    return *this;
2396}
2397
2398template <class _CharT, class _Traits, class _Allocator>
2399basic_string<_CharT, _Traits, _Allocator>&
2400basic_string<_CharT, _Traits, _Allocator>::operator=(const basic_string& __str)
2401{
2402  if (this != &__str) {
2403    __copy_assign_alloc(__str);
2404    if (!__is_long()) {
2405      if (!__str.__is_long()) {
2406        __r_.first().__r = __str.__r_.first().__r;
2407      } else {
2408        return __assign_no_alias<true>(__str.data(), __str.size());
2409      }
2410    } else {
2411      return __assign_no_alias<false>(__str.data(), __str.size());
2412    }
2413  }
2414  return *this;
2415}
2416
2417#ifndef _LIBCPP_CXX03_LANG
2418
2419template <class _CharT, class _Traits, class _Allocator>
2420inline
2421void
2422basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, false_type)
2423    _NOEXCEPT_(__alloc_traits::is_always_equal::value)
2424{
2425    if (__alloc() != __str.__alloc())
2426        assign(__str);
2427    else
2428        __move_assign(__str, true_type());
2429}
2430
2431template <class _CharT, class _Traits, class _Allocator>
2432inline
2433void
2434basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, true_type)
2435#if _LIBCPP_STD_VER > 14
2436    _NOEXCEPT
2437#else
2438    _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
2439#endif
2440{
2441  if (__is_long()) {
2442    __alloc_traits::deallocate(__alloc(), __get_long_pointer(),
2443                               __get_long_cap());
2444#if _LIBCPP_STD_VER <= 14
2445    if (!is_nothrow_move_assignable<allocator_type>::value) {
2446      __set_short_size(0);
2447      traits_type::assign(__get_short_pointer()[0], value_type());
2448    }
2449#endif
2450  }
2451  __move_assign_alloc(__str);
2452  __r_.first() = __str.__r_.first();
2453  __str.__set_short_size(0);
2454  traits_type::assign(__str.__get_short_pointer()[0], value_type());
2455}
2456
2457template <class _CharT, class _Traits, class _Allocator>
2458inline
2459basic_string<_CharT, _Traits, _Allocator>&
2460basic_string<_CharT, _Traits, _Allocator>::operator=(basic_string&& __str)
2461    _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
2462{
2463    __move_assign(__str, integral_constant<bool,
2464          __alloc_traits::propagate_on_container_move_assignment::value>());
2465    return *this;
2466}
2467
2468#endif
2469
2470template <class _CharT, class _Traits, class _Allocator>
2471template<class _InputIterator>
2472__enable_if_t
2473<
2474     __is_exactly_cpp17_input_iterator<_InputIterator>::value,
2475    basic_string<_CharT, _Traits, _Allocator>&
2476>
2477basic_string<_CharT, _Traits, _Allocator>::assign(_InputIterator __first, _InputIterator __last)
2478{
2479    const basic_string __temp(__first, __last, __alloc());
2480    assign(__temp.data(), __temp.size());
2481    return *this;
2482}
2483
2484template <class _CharT, class _Traits, class _Allocator>
2485template<class _ForwardIterator>
2486__enable_if_t
2487<
2488    __is_cpp17_forward_iterator<_ForwardIterator>::value,
2489    basic_string<_CharT, _Traits, _Allocator>&
2490>
2491basic_string<_CharT, _Traits, _Allocator>::assign(_ForwardIterator __first, _ForwardIterator __last)
2492{
2493    size_type __cap = capacity();
2494    size_type __n = __string_is_trivial_iterator<_ForwardIterator>::value ?
2495        static_cast<size_type>(_VSTD::distance(__first, __last)) : 0;
2496
2497    if (__string_is_trivial_iterator<_ForwardIterator>::value &&
2498        (__cap >= __n || !__addr_in_range(*__first)))
2499    {
2500        if (__cap < __n)
2501        {
2502            size_type __sz = size();
2503            __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2504        }
2505        pointer __p = __get_pointer();
2506        for (; __first != __last; ++__p, (void) ++__first)
2507            traits_type::assign(*__p, *__first);
2508        traits_type::assign(*__p, value_type());
2509        __set_size(__n);
2510        __invalidate_iterators_past(__n);
2511    }
2512    else
2513    {
2514        const basic_string __temp(__first, __last, __alloc());
2515        assign(__temp.data(), __temp.size());
2516    }
2517    return *this;
2518}
2519
2520template <class _CharT, class _Traits, class _Allocator>
2521basic_string<_CharT, _Traits, _Allocator>&
2522basic_string<_CharT, _Traits, _Allocator>::assign(const basic_string& __str, size_type __pos, size_type __n)
2523{
2524    size_type __sz = __str.size();
2525    if (__pos > __sz)
2526        this->__throw_out_of_range();
2527    return assign(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2528}
2529
2530template <class _CharT, class _Traits, class _Allocator>
2531template <class _Tp>
2532__enable_if_t
2533<
2534    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
2535    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2536    basic_string<_CharT, _Traits, _Allocator>&
2537>
2538basic_string<_CharT, _Traits, _Allocator>::assign(const _Tp & __t, size_type __pos, size_type __n)
2539{
2540    __self_view __sv = __t;
2541    size_type __sz = __sv.size();
2542    if (__pos > __sz)
2543        this->__throw_out_of_range();
2544    return assign(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2545}
2546
2547
2548template <class _CharT, class _Traits, class _Allocator>
2549basic_string<_CharT, _Traits, _Allocator>&
2550basic_string<_CharT, _Traits, _Allocator>::__assign_external(const value_type* __s) {
2551  return __assign_external(__s, traits_type::length(__s));
2552}
2553
2554template <class _CharT, class _Traits, class _Allocator>
2555basic_string<_CharT, _Traits, _Allocator>&
2556basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s)
2557{
2558    _LIBCPP_ASSERT(__s != nullptr, "string::assign received nullptr");
2559    return __builtin_constant_p(*__s)
2560               ? (__fits_in_sso(traits_type::length(__s))
2561                      ? __assign_short(__s, traits_type::length(__s))
2562                      : __assign_external(__s, traits_type::length(__s)))
2563               : __assign_external(__s);
2564}
2565// append
2566
2567template <class _CharT, class _Traits, class _Allocator>
2568basic_string<_CharT, _Traits, _Allocator>&
2569basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s, size_type __n)
2570{
2571    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::append received nullptr");
2572    size_type __cap = capacity();
2573    size_type __sz = size();
2574    if (__cap - __sz >= __n)
2575    {
2576        if (__n)
2577        {
2578            value_type* __p = _VSTD::__to_address(__get_pointer());
2579            traits_type::copy(__p + __sz, __s, __n);
2580            __sz += __n;
2581            __set_size(__sz);
2582            traits_type::assign(__p[__sz], value_type());
2583        }
2584    }
2585    else
2586        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __sz, 0, __n, __s);
2587    return *this;
2588}
2589
2590template <class _CharT, class _Traits, class _Allocator>
2591basic_string<_CharT, _Traits, _Allocator>&
2592basic_string<_CharT, _Traits, _Allocator>::append(size_type __n, value_type __c)
2593{
2594    if (__n)
2595    {
2596        size_type __cap = capacity();
2597        size_type __sz = size();
2598        if (__cap - __sz < __n)
2599            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2600        pointer __p = __get_pointer();
2601        traits_type::assign(_VSTD::__to_address(__p) + __sz, __n, __c);
2602        __sz += __n;
2603        __set_size(__sz);
2604        traits_type::assign(__p[__sz], value_type());
2605    }
2606    return *this;
2607}
2608
2609template <class _CharT, class _Traits, class _Allocator>
2610inline void
2611basic_string<_CharT, _Traits, _Allocator>::__append_default_init(size_type __n)
2612{
2613    if (__n)
2614    {
2615        size_type __cap = capacity();
2616        size_type __sz = size();
2617        if (__cap - __sz < __n)
2618            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2619        pointer __p = __get_pointer();
2620        __sz += __n;
2621        __set_size(__sz);
2622        traits_type::assign(__p[__sz], value_type());
2623    }
2624}
2625
2626template <class _CharT, class _Traits, class _Allocator>
2627void
2628basic_string<_CharT, _Traits, _Allocator>::push_back(value_type __c)
2629{
2630    bool __is_short = !__is_long();
2631    size_type __cap;
2632    size_type __sz;
2633    if (__is_short)
2634    {
2635        __cap = __min_cap - 1;
2636        __sz = __get_short_size();
2637    }
2638    else
2639    {
2640        __cap = __get_long_cap() - 1;
2641        __sz = __get_long_size();
2642    }
2643    if (__sz == __cap)
2644    {
2645        __grow_by(__cap, 1, __sz, __sz, 0);
2646        __is_short = false; // the string is always long after __grow_by
2647    }
2648    pointer __p;
2649    if (__is_short)
2650    {
2651        __p = __get_short_pointer() + __sz;
2652        __set_short_size(__sz+1);
2653    }
2654    else
2655    {
2656        __p = __get_long_pointer() + __sz;
2657        __set_long_size(__sz+1);
2658    }
2659    traits_type::assign(*__p, __c);
2660    traits_type::assign(*++__p, value_type());
2661}
2662
2663template <class _CharT, class _Traits, class _Allocator>
2664template<class _ForwardIterator>
2665__enable_if_t
2666<
2667    __is_cpp17_forward_iterator<_ForwardIterator>::value,
2668    basic_string<_CharT, _Traits, _Allocator>&
2669>
2670basic_string<_CharT, _Traits, _Allocator>::append(
2671    _ForwardIterator __first, _ForwardIterator __last)
2672{
2673    size_type __sz = size();
2674    size_type __cap = capacity();
2675    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2676    if (__n)
2677    {
2678        if (__string_is_trivial_iterator<_ForwardIterator>::value &&
2679            !__addr_in_range(*__first))
2680        {
2681            if (__cap - __sz < __n)
2682                __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2683            pointer __p = __get_pointer() + __sz;
2684            for (; __first != __last; ++__p, (void) ++__first)
2685                traits_type::assign(*__p, *__first);
2686            traits_type::assign(*__p, value_type());
2687            __set_size(__sz + __n);
2688        }
2689        else
2690        {
2691            const basic_string __temp(__first, __last, __alloc());
2692            append(__temp.data(), __temp.size());
2693        }
2694    }
2695    return *this;
2696}
2697
2698template <class _CharT, class _Traits, class _Allocator>
2699inline
2700basic_string<_CharT, _Traits, _Allocator>&
2701basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str)
2702{
2703    return append(__str.data(), __str.size());
2704}
2705
2706template <class _CharT, class _Traits, class _Allocator>
2707basic_string<_CharT, _Traits, _Allocator>&
2708basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str, size_type __pos, size_type __n)
2709{
2710    size_type __sz = __str.size();
2711    if (__pos > __sz)
2712        this->__throw_out_of_range();
2713    return append(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2714}
2715
2716template <class _CharT, class _Traits, class _Allocator>
2717template <class _Tp>
2718    __enable_if_t
2719    <
2720        __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2721        basic_string<_CharT, _Traits, _Allocator>&
2722    >
2723basic_string<_CharT, _Traits, _Allocator>::append(const _Tp & __t, size_type __pos, size_type __n)
2724{
2725    __self_view __sv = __t;
2726    size_type __sz = __sv.size();
2727    if (__pos > __sz)
2728        this->__throw_out_of_range();
2729    return append(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2730}
2731
2732template <class _CharT, class _Traits, class _Allocator>
2733basic_string<_CharT, _Traits, _Allocator>&
2734basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s)
2735{
2736    _LIBCPP_ASSERT(__s != nullptr, "string::append received nullptr");
2737    return append(__s, traits_type::length(__s));
2738}
2739
2740// insert
2741
2742template <class _CharT, class _Traits, class _Allocator>
2743basic_string<_CharT, _Traits, _Allocator>&
2744basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s, size_type __n)
2745{
2746    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::insert received nullptr");
2747    size_type __sz = size();
2748    if (__pos > __sz)
2749        this->__throw_out_of_range();
2750    size_type __cap = capacity();
2751    if (__cap - __sz >= __n)
2752    {
2753        if (__n)
2754        {
2755            value_type* __p = _VSTD::__to_address(__get_pointer());
2756            size_type __n_move = __sz - __pos;
2757            if (__n_move != 0)
2758            {
2759                if (__p + __pos <= __s && __s < __p + __sz)
2760                    __s += __n;
2761                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2762            }
2763            traits_type::move(__p + __pos, __s, __n);
2764            __sz += __n;
2765            __set_size(__sz);
2766            traits_type::assign(__p[__sz], value_type());
2767        }
2768    }
2769    else
2770        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __pos, 0, __n, __s);
2771    return *this;
2772}
2773
2774template <class _CharT, class _Traits, class _Allocator>
2775basic_string<_CharT, _Traits, _Allocator>&
2776basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, size_type __n, value_type __c)
2777{
2778    size_type __sz = size();
2779    if (__pos > __sz)
2780        this->__throw_out_of_range();
2781    if (__n)
2782    {
2783        size_type __cap = capacity();
2784        value_type* __p;
2785        if (__cap - __sz >= __n)
2786        {
2787            __p = _VSTD::__to_address(__get_pointer());
2788            size_type __n_move = __sz - __pos;
2789            if (__n_move != 0)
2790                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2791        }
2792        else
2793        {
2794            __grow_by(__cap, __sz + __n - __cap, __sz, __pos, 0, __n);
2795            __p = _VSTD::__to_address(__get_long_pointer());
2796        }
2797        traits_type::assign(__p + __pos, __n, __c);
2798        __sz += __n;
2799        __set_size(__sz);
2800        traits_type::assign(__p[__sz], value_type());
2801    }
2802    return *this;
2803}
2804
2805template <class _CharT, class _Traits, class _Allocator>
2806template<class _InputIterator>
2807__enable_if_t
2808<
2809   __is_exactly_cpp17_input_iterator<_InputIterator>::value,
2810   typename basic_string<_CharT, _Traits, _Allocator>::iterator
2811>
2812basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _InputIterator __first, _InputIterator __last)
2813{
2814  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2815                       "string::insert(iterator, range) called with an iterator not"
2816                       " referring to this string");
2817  const basic_string __temp(__first, __last, __alloc());
2818  return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2819}
2820
2821template <class _CharT, class _Traits, class _Allocator>
2822template<class _ForwardIterator>
2823__enable_if_t
2824<
2825    __is_cpp17_forward_iterator<_ForwardIterator>::value,
2826    typename basic_string<_CharT, _Traits, _Allocator>::iterator
2827>
2828basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last)
2829{
2830  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2831                       "string::insert(iterator, range) called with an iterator not"
2832                       " referring to this string");
2833
2834    size_type __ip = static_cast<size_type>(__pos - begin());
2835    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2836    if (__n)
2837    {
2838        if (__string_is_trivial_iterator<_ForwardIterator>::value &&
2839            !__addr_in_range(*__first))
2840        {
2841            size_type __sz = size();
2842            size_type __cap = capacity();
2843            value_type* __p;
2844            if (__cap - __sz >= __n)
2845            {
2846                __p = _VSTD::__to_address(__get_pointer());
2847                size_type __n_move = __sz - __ip;
2848                if (__n_move != 0)
2849                    traits_type::move(__p + __ip + __n, __p + __ip, __n_move);
2850            }
2851            else
2852            {
2853                __grow_by(__cap, __sz + __n - __cap, __sz, __ip, 0, __n);
2854                __p = _VSTD::__to_address(__get_long_pointer());
2855            }
2856            __sz += __n;
2857            __set_size(__sz);
2858            traits_type::assign(__p[__sz], value_type());
2859            for (__p += __ip; __first != __last; ++__p, (void) ++__first)
2860                traits_type::assign(*__p, *__first);
2861        }
2862        else
2863        {
2864            const basic_string __temp(__first, __last, __alloc());
2865            return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2866        }
2867    }
2868    return begin() + __ip;
2869}
2870
2871template <class _CharT, class _Traits, class _Allocator>
2872inline
2873basic_string<_CharT, _Traits, _Allocator>&
2874basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str)
2875{
2876    return insert(__pos1, __str.data(), __str.size());
2877}
2878
2879template <class _CharT, class _Traits, class _Allocator>
2880basic_string<_CharT, _Traits, _Allocator>&
2881basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str,
2882                                                  size_type __pos2, size_type __n)
2883{
2884    size_type __str_sz = __str.size();
2885    if (__pos2 > __str_sz)
2886        this->__throw_out_of_range();
2887    return insert(__pos1, __str.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2888}
2889
2890template <class _CharT, class _Traits, class _Allocator>
2891template <class _Tp>
2892__enable_if_t
2893<
2894    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2895    basic_string<_CharT, _Traits, _Allocator>&
2896>
2897basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const _Tp& __t,
2898                                                  size_type __pos2, size_type __n)
2899{
2900    __self_view __sv = __t;
2901    size_type __str_sz = __sv.size();
2902    if (__pos2 > __str_sz)
2903        this->__throw_out_of_range();
2904    return insert(__pos1, __sv.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2905}
2906
2907template <class _CharT, class _Traits, class _Allocator>
2908basic_string<_CharT, _Traits, _Allocator>&
2909basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s)
2910{
2911    _LIBCPP_ASSERT(__s != nullptr, "string::insert received nullptr");
2912    return insert(__pos, __s, traits_type::length(__s));
2913}
2914
2915template <class _CharT, class _Traits, class _Allocator>
2916typename basic_string<_CharT, _Traits, _Allocator>::iterator
2917basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, value_type __c)
2918{
2919    size_type __ip = static_cast<size_type>(__pos - begin());
2920    size_type __sz = size();
2921    size_type __cap = capacity();
2922    value_type* __p;
2923    if (__cap == __sz)
2924    {
2925        __grow_by(__cap, 1, __sz, __ip, 0, 1);
2926        __p = _VSTD::__to_address(__get_long_pointer());
2927    }
2928    else
2929    {
2930        __p = _VSTD::__to_address(__get_pointer());
2931        size_type __n_move = __sz - __ip;
2932        if (__n_move != 0)
2933            traits_type::move(__p + __ip + 1, __p + __ip, __n_move);
2934    }
2935    traits_type::assign(__p[__ip], __c);
2936    traits_type::assign(__p[++__sz], value_type());
2937    __set_size(__sz);
2938    return begin() + static_cast<difference_type>(__ip);
2939}
2940
2941template <class _CharT, class _Traits, class _Allocator>
2942inline
2943typename basic_string<_CharT, _Traits, _Allocator>::iterator
2944basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, size_type __n, value_type __c)
2945{
2946  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2947                       "string::insert(iterator, n, value) called with an iterator not"
2948                       " referring to this string");
2949  difference_type __p = __pos - begin();
2950  insert(static_cast<size_type>(__p), __n, __c);
2951  return begin() + __p;
2952}
2953
2954// replace
2955
2956template <class _CharT, class _Traits, class _Allocator>
2957basic_string<_CharT, _Traits, _Allocator>&
2958basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2)
2959    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
2960{
2961    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::replace received nullptr");
2962    size_type __sz = size();
2963    if (__pos > __sz)
2964        this->__throw_out_of_range();
2965    __n1 = _VSTD::min(__n1, __sz - __pos);
2966    size_type __cap = capacity();
2967    if (__cap - __sz + __n1 >= __n2)
2968    {
2969        value_type* __p = _VSTD::__to_address(__get_pointer());
2970        if (__n1 != __n2)
2971        {
2972            size_type __n_move = __sz - __pos - __n1;
2973            if (__n_move != 0)
2974            {
2975                if (__n1 > __n2)
2976                {
2977                    traits_type::move(__p + __pos, __s, __n2);
2978                    traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
2979                    return __null_terminate_at(__p, __sz + (__n2 - __n1));
2980                }
2981                if (__p + __pos < __s && __s < __p + __sz)
2982                {
2983                    if (__p + __pos + __n1 <= __s)
2984                        __s += __n2 - __n1;
2985                    else // __p + __pos < __s < __p + __pos + __n1
2986                    {
2987                        traits_type::move(__p + __pos, __s, __n1);
2988                        __pos += __n1;
2989                        __s += __n2;
2990                        __n2 -= __n1;
2991                        __n1 = 0;
2992                    }
2993                }
2994                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
2995            }
2996        }
2997        traits_type::move(__p + __pos, __s, __n2);
2998        return __null_terminate_at(__p, __sz + (__n2 - __n1));
2999    }
3000    else
3001        __grow_by_and_replace(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2, __s);
3002    return *this;
3003}
3004
3005template <class _CharT, class _Traits, class _Allocator>
3006basic_string<_CharT, _Traits, _Allocator>&
3007basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, size_type __n2, value_type __c)
3008{
3009    size_type __sz = size();
3010    if (__pos > __sz)
3011        this->__throw_out_of_range();
3012    __n1 = _VSTD::min(__n1, __sz - __pos);
3013    size_type __cap = capacity();
3014    value_type* __p;
3015    if (__cap - __sz + __n1 >= __n2)
3016    {
3017        __p = _VSTD::__to_address(__get_pointer());
3018        if (__n1 != __n2)
3019        {
3020            size_type __n_move = __sz - __pos - __n1;
3021            if (__n_move != 0)
3022                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
3023        }
3024    }
3025    else
3026    {
3027        __grow_by(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2);
3028        __p = _VSTD::__to_address(__get_long_pointer());
3029    }
3030    traits_type::assign(__p + __pos, __n2, __c);
3031    return __null_terminate_at(__p, __sz - (__n1 - __n2));
3032}
3033
3034template <class _CharT, class _Traits, class _Allocator>
3035template<class _InputIterator>
3036__enable_if_t
3037<
3038    __is_cpp17_input_iterator<_InputIterator>::value,
3039    basic_string<_CharT, _Traits, _Allocator>&
3040>
3041basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2,
3042                                                   _InputIterator __j1, _InputIterator __j2)
3043{
3044    const basic_string __temp(__j1, __j2, __alloc());
3045    return this->replace(__i1, __i2, __temp);
3046}
3047
3048template <class _CharT, class _Traits, class _Allocator>
3049inline
3050basic_string<_CharT, _Traits, _Allocator>&
3051basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str)
3052{
3053    return replace(__pos1, __n1, __str.data(), __str.size());
3054}
3055
3056template <class _CharT, class _Traits, class _Allocator>
3057basic_string<_CharT, _Traits, _Allocator>&
3058basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str,
3059                                                   size_type __pos2, size_type __n2)
3060{
3061    size_type __str_sz = __str.size();
3062    if (__pos2 > __str_sz)
3063        this->__throw_out_of_range();
3064    return replace(__pos1, __n1, __str.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
3065}
3066
3067template <class _CharT, class _Traits, class _Allocator>
3068template <class _Tp>
3069__enable_if_t
3070<
3071    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
3072    basic_string<_CharT, _Traits, _Allocator>&
3073>
3074basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const _Tp& __t,
3075                                                   size_type __pos2, size_type __n2)
3076{
3077    __self_view __sv = __t;
3078    size_type __str_sz = __sv.size();
3079    if (__pos2 > __str_sz)
3080        this->__throw_out_of_range();
3081    return replace(__pos1, __n1, __sv.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
3082}
3083
3084template <class _CharT, class _Traits, class _Allocator>
3085basic_string<_CharT, _Traits, _Allocator>&
3086basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s)
3087{
3088    _LIBCPP_ASSERT(__s != nullptr, "string::replace received nullptr");
3089    return replace(__pos, __n1, __s, traits_type::length(__s));
3090}
3091
3092template <class _CharT, class _Traits, class _Allocator>
3093inline
3094basic_string<_CharT, _Traits, _Allocator>&
3095basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const basic_string& __str)
3096{
3097    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1),
3098                   __str.data(), __str.size());
3099}
3100
3101template <class _CharT, class _Traits, class _Allocator>
3102inline
3103basic_string<_CharT, _Traits, _Allocator>&
3104basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n)
3105{
3106    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s, __n);
3107}
3108
3109template <class _CharT, class _Traits, class _Allocator>
3110inline
3111basic_string<_CharT, _Traits, _Allocator>&
3112basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s)
3113{
3114    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s);
3115}
3116
3117template <class _CharT, class _Traits, class _Allocator>
3118inline
3119basic_string<_CharT, _Traits, _Allocator>&
3120basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c)
3121{
3122    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __n, __c);
3123}
3124
3125// erase
3126
3127// 'externally instantiated' erase() implementation, called when __n != npos.
3128// Does not check __pos against size()
3129template <class _CharT, class _Traits, class _Allocator>
3130void
3131basic_string<_CharT, _Traits, _Allocator>::__erase_external_with_move(
3132    size_type __pos, size_type __n)
3133{
3134    if (__n)
3135    {
3136        size_type __sz = size();
3137        value_type* __p = _VSTD::__to_address(__get_pointer());
3138        __n = _VSTD::min(__n, __sz - __pos);
3139        size_type __n_move = __sz - __pos - __n;
3140        if (__n_move != 0)
3141            traits_type::move(__p + __pos, __p + __pos + __n, __n_move);
3142        __null_terminate_at(__p, __sz - __n);
3143    }
3144}
3145
3146template <class _CharT, class _Traits, class _Allocator>
3147basic_string<_CharT, _Traits, _Allocator>&
3148basic_string<_CharT, _Traits, _Allocator>::erase(size_type __pos,
3149                                                 size_type __n) {
3150  if (__pos > size()) this->__throw_out_of_range();
3151  if (__n == npos) {
3152    __erase_to_end(__pos);
3153  } else {
3154    __erase_external_with_move(__pos, __n);
3155  }
3156  return *this;
3157}
3158
3159template <class _CharT, class _Traits, class _Allocator>
3160inline
3161typename basic_string<_CharT, _Traits, _Allocator>::iterator
3162basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __pos)
3163{
3164  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
3165                       "string::erase(iterator) called with an iterator not"
3166                       " referring to this string");
3167
3168  _LIBCPP_ASSERT(__pos != end(), "string::erase(iterator) called with a non-dereferenceable iterator");
3169  iterator __b = begin();
3170  size_type __r = static_cast<size_type>(__pos - __b);
3171  erase(__r, 1);
3172  return __b + static_cast<difference_type>(__r);
3173}
3174
3175template <class _CharT, class _Traits, class _Allocator>
3176inline
3177typename basic_string<_CharT, _Traits, _Allocator>::iterator
3178basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __first, const_iterator __last)
3179{
3180  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__first) == this,
3181                       "string::erase(iterator,  iterator) called with an iterator not"
3182                       " referring to this string");
3183
3184  _LIBCPP_ASSERT(__first <= __last, "string::erase(first, last) called with invalid range");
3185  iterator __b = begin();
3186  size_type __r = static_cast<size_type>(__first - __b);
3187  erase(__r, static_cast<size_type>(__last - __first));
3188  return __b + static_cast<difference_type>(__r);
3189}
3190
3191template <class _CharT, class _Traits, class _Allocator>
3192inline
3193void
3194basic_string<_CharT, _Traits, _Allocator>::pop_back()
3195{
3196    _LIBCPP_ASSERT(!empty(), "string::pop_back(): string is already empty");
3197    __erase_to_end(size() - 1);
3198}
3199
3200template <class _CharT, class _Traits, class _Allocator>
3201inline
3202void
3203basic_string<_CharT, _Traits, _Allocator>::clear() _NOEXCEPT
3204{
3205    __invalidate_all_iterators();
3206    if (__is_long())
3207    {
3208        traits_type::assign(*__get_long_pointer(), value_type());
3209        __set_long_size(0);
3210    }
3211    else
3212    {
3213        traits_type::assign(*__get_short_pointer(), value_type());
3214        __set_short_size(0);
3215    }
3216}
3217
3218template <class _CharT, class _Traits, class _Allocator>
3219inline
3220void
3221basic_string<_CharT, _Traits, _Allocator>::__erase_to_end(size_type __pos)
3222{
3223  __null_terminate_at(_VSTD::__to_address(__get_pointer()), __pos);
3224}
3225
3226template <class _CharT, class _Traits, class _Allocator>
3227void
3228basic_string<_CharT, _Traits, _Allocator>::resize(size_type __n, value_type __c)
3229{
3230    size_type __sz = size();
3231    if (__n > __sz)
3232        append(__n - __sz, __c);
3233    else
3234        __erase_to_end(__n);
3235}
3236
3237template <class _CharT, class _Traits, class _Allocator>
3238inline void
3239basic_string<_CharT, _Traits, _Allocator>::__resize_default_init(size_type __n)
3240{
3241    size_type __sz = size();
3242    if (__n > __sz) {
3243       __append_default_init(__n - __sz);
3244    } else
3245        __erase_to_end(__n);
3246}
3247
3248template <class _CharT, class _Traits, class _Allocator>
3249inline
3250typename basic_string<_CharT, _Traits, _Allocator>::size_type
3251basic_string<_CharT, _Traits, _Allocator>::max_size() const _NOEXCEPT
3252{
3253    size_type __m = __alloc_traits::max_size(__alloc());
3254#ifdef _LIBCPP_BIG_ENDIAN
3255    return (__m <= ~__long_mask ? __m : __m/2) - __alignment;
3256#else
3257    return __m - __alignment;
3258#endif
3259}
3260
3261template <class _CharT, class _Traits, class _Allocator>
3262void
3263basic_string<_CharT, _Traits, _Allocator>::reserve(size_type __requested_capacity)
3264{
3265    if (__requested_capacity > max_size())
3266        this->__throw_length_error();
3267
3268#if _LIBCPP_STD_VER > 17
3269    // Reserve never shrinks as of C++20.
3270    if (__requested_capacity <= capacity()) return;
3271#endif
3272
3273    size_type __target_capacity = _VSTD::max(__requested_capacity, size());
3274    __target_capacity = __recommend(__target_capacity);
3275    if (__target_capacity == capacity()) return;
3276
3277    __shrink_or_extend(__target_capacity);
3278}
3279
3280template <class _CharT, class _Traits, class _Allocator>
3281inline
3282void
3283basic_string<_CharT, _Traits, _Allocator>::shrink_to_fit() _NOEXCEPT
3284{
3285    size_type __target_capacity = __recommend(size());
3286    if (__target_capacity == capacity()) return;
3287
3288    __shrink_or_extend(__target_capacity);
3289}
3290
3291template <class _CharT, class _Traits, class _Allocator>
3292inline
3293void
3294basic_string<_CharT, _Traits, _Allocator>::__shrink_or_extend(size_type __target_capacity)
3295{
3296    size_type __cap = capacity();
3297    size_type __sz = size();
3298
3299    pointer __new_data, __p;
3300    bool __was_long, __now_long;
3301    if (__target_capacity == __min_cap - 1)
3302    {
3303        __was_long = true;
3304        __now_long = false;
3305        __new_data = __get_short_pointer();
3306        __p = __get_long_pointer();
3307    }
3308    else
3309    {
3310        if (__target_capacity > __cap)
3311            __new_data = __alloc_traits::allocate(__alloc(), __target_capacity+1);
3312        else
3313        {
3314        #ifndef _LIBCPP_NO_EXCEPTIONS
3315            try
3316            {
3317        #endif // _LIBCPP_NO_EXCEPTIONS
3318                __new_data = __alloc_traits::allocate(__alloc(), __target_capacity+1);
3319        #ifndef _LIBCPP_NO_EXCEPTIONS
3320            }
3321            catch (...)
3322            {
3323                return;
3324            }
3325        #else  // _LIBCPP_NO_EXCEPTIONS
3326            if (__new_data == nullptr)
3327                return;
3328        #endif // _LIBCPP_NO_EXCEPTIONS
3329        }
3330        __now_long = true;
3331        __was_long = __is_long();
3332        __p = __get_pointer();
3333    }
3334    traits_type::copy(_VSTD::__to_address(__new_data),
3335                        _VSTD::__to_address(__p), size()+1);
3336    if (__was_long)
3337        __alloc_traits::deallocate(__alloc(), __p, __cap+1);
3338    if (__now_long)
3339    {
3340        __set_long_cap(__target_capacity+1);
3341        __set_long_size(__sz);
3342        __set_long_pointer(__new_data);
3343    }
3344    else
3345        __set_short_size(__sz);
3346    __invalidate_all_iterators();
3347}
3348
3349template <class _CharT, class _Traits, class _Allocator>
3350inline
3351typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3352basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) const _NOEXCEPT
3353{
3354    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3355    return *(data() + __pos);
3356}
3357
3358template <class _CharT, class _Traits, class _Allocator>
3359inline
3360typename basic_string<_CharT, _Traits, _Allocator>::reference
3361basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) _NOEXCEPT
3362{
3363    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3364    return *(__get_pointer() + __pos);
3365}
3366
3367template <class _CharT, class _Traits, class _Allocator>
3368typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3369basic_string<_CharT, _Traits, _Allocator>::at(size_type __n) const
3370{
3371    if (__n >= size())
3372        this->__throw_out_of_range();
3373    return (*this)[__n];
3374}
3375
3376template <class _CharT, class _Traits, class _Allocator>
3377typename basic_string<_CharT, _Traits, _Allocator>::reference
3378basic_string<_CharT, _Traits, _Allocator>::at(size_type __n)
3379{
3380    if (__n >= size())
3381        this->__throw_out_of_range();
3382    return (*this)[__n];
3383}
3384
3385template <class _CharT, class _Traits, class _Allocator>
3386inline
3387typename basic_string<_CharT, _Traits, _Allocator>::reference
3388basic_string<_CharT, _Traits, _Allocator>::front() _NOEXCEPT
3389{
3390    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3391    return *__get_pointer();
3392}
3393
3394template <class _CharT, class _Traits, class _Allocator>
3395inline
3396typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3397basic_string<_CharT, _Traits, _Allocator>::front() const _NOEXCEPT
3398{
3399    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3400    return *data();
3401}
3402
3403template <class _CharT, class _Traits, class _Allocator>
3404inline
3405typename basic_string<_CharT, _Traits, _Allocator>::reference
3406basic_string<_CharT, _Traits, _Allocator>::back() _NOEXCEPT
3407{
3408    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3409    return *(__get_pointer() + size() - 1);
3410}
3411
3412template <class _CharT, class _Traits, class _Allocator>
3413inline
3414typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3415basic_string<_CharT, _Traits, _Allocator>::back() const _NOEXCEPT
3416{
3417    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3418    return *(data() + size() - 1);
3419}
3420
3421template <class _CharT, class _Traits, class _Allocator>
3422typename basic_string<_CharT, _Traits, _Allocator>::size_type
3423basic_string<_CharT, _Traits, _Allocator>::copy(value_type* __s, size_type __n, size_type __pos) const
3424{
3425    size_type __sz = size();
3426    if (__pos > __sz)
3427        this->__throw_out_of_range();
3428    size_type __rlen = _VSTD::min(__n, __sz - __pos);
3429    traits_type::copy(__s, data() + __pos, __rlen);
3430    return __rlen;
3431}
3432
3433template <class _CharT, class _Traits, class _Allocator>
3434inline
3435basic_string<_CharT, _Traits, _Allocator>
3436basic_string<_CharT, _Traits, _Allocator>::substr(size_type __pos, size_type __n) const
3437{
3438    return basic_string(*this, __pos, __n, __alloc());
3439}
3440
3441template <class _CharT, class _Traits, class _Allocator>
3442inline
3443void
3444basic_string<_CharT, _Traits, _Allocator>::swap(basic_string& __str)
3445#if _LIBCPP_STD_VER >= 14
3446        _NOEXCEPT
3447#else
3448        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
3449                    __is_nothrow_swappable<allocator_type>::value)
3450#endif
3451{
3452#if _LIBCPP_DEBUG_LEVEL == 2
3453    if (!__libcpp_is_constant_evaluated()) {
3454        if (!__is_long())
3455            __get_db()->__invalidate_all(this);
3456        if (!__str.__is_long())
3457            __get_db()->__invalidate_all(&__str);
3458        __get_db()->swap(this, &__str);
3459    }
3460#endif
3461    _LIBCPP_ASSERT(
3462        __alloc_traits::propagate_on_container_swap::value ||
3463        __alloc_traits::is_always_equal::value ||
3464        __alloc() == __str.__alloc(), "swapping non-equal allocators");
3465    _VSTD::swap(__r_.first(), __str.__r_.first());
3466    _VSTD::__swap_allocator(__alloc(), __str.__alloc());
3467}
3468
3469// find
3470
3471template <class _Traits>
3472struct _LIBCPP_HIDDEN __traits_eq
3473{
3474    typedef typename _Traits::char_type char_type;
3475    _LIBCPP_INLINE_VISIBILITY
3476    bool operator()(const char_type& __x, const char_type& __y) _NOEXCEPT
3477        {return _Traits::eq(__x, __y);}
3478};
3479
3480template<class _CharT, class _Traits, class _Allocator>
3481typename basic_string<_CharT, _Traits, _Allocator>::size_type
3482basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3483                                                size_type __pos,
3484                                                size_type __n) const _NOEXCEPT
3485{
3486    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find(): received nullptr");
3487    return __str_find<value_type, size_type, traits_type, npos>
3488        (data(), size(), __s, __pos, __n);
3489}
3490
3491template<class _CharT, class _Traits, class _Allocator>
3492inline
3493typename basic_string<_CharT, _Traits, _Allocator>::size_type
3494basic_string<_CharT, _Traits, _Allocator>::find(const basic_string& __str,
3495                                                size_type __pos) const _NOEXCEPT
3496{
3497    return __str_find<value_type, size_type, traits_type, npos>
3498        (data(), size(), __str.data(), __pos, __str.size());
3499}
3500
3501template<class _CharT, class _Traits, class _Allocator>
3502template <class _Tp>
3503__enable_if_t
3504<
3505    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3506    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3507>
3508basic_string<_CharT, _Traits, _Allocator>::find(const _Tp &__t,
3509                                                size_type __pos) const _NOEXCEPT
3510{
3511    __self_view __sv = __t;
3512    return __str_find<value_type, size_type, traits_type, npos>
3513        (data(), size(), __sv.data(), __pos, __sv.size());
3514}
3515
3516template<class _CharT, class _Traits, class _Allocator>
3517inline
3518typename basic_string<_CharT, _Traits, _Allocator>::size_type
3519basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3520                                                size_type __pos) const _NOEXCEPT
3521{
3522    _LIBCPP_ASSERT(__s != nullptr, "string::find(): received nullptr");
3523    return __str_find<value_type, size_type, traits_type, npos>
3524        (data(), size(), __s, __pos, traits_type::length(__s));
3525}
3526
3527template<class _CharT, class _Traits, class _Allocator>
3528typename basic_string<_CharT, _Traits, _Allocator>::size_type
3529basic_string<_CharT, _Traits, _Allocator>::find(value_type __c,
3530                                                size_type __pos) const _NOEXCEPT
3531{
3532    return __str_find<value_type, size_type, traits_type, npos>
3533        (data(), size(), __c, __pos);
3534}
3535
3536// rfind
3537
3538template<class _CharT, class _Traits, class _Allocator>
3539typename basic_string<_CharT, _Traits, _Allocator>::size_type
3540basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3541                                                 size_type __pos,
3542                                                 size_type __n) const _NOEXCEPT
3543{
3544    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::rfind(): received nullptr");
3545    return __str_rfind<value_type, size_type, traits_type, npos>
3546        (data(), size(), __s, __pos, __n);
3547}
3548
3549template<class _CharT, class _Traits, class _Allocator>
3550inline
3551typename basic_string<_CharT, _Traits, _Allocator>::size_type
3552basic_string<_CharT, _Traits, _Allocator>::rfind(const basic_string& __str,
3553                                                 size_type __pos) const _NOEXCEPT
3554{
3555    return __str_rfind<value_type, size_type, traits_type, npos>
3556        (data(), size(), __str.data(), __pos, __str.size());
3557}
3558
3559template<class _CharT, class _Traits, class _Allocator>
3560template <class _Tp>
3561__enable_if_t
3562<
3563    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3564    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3565>
3566basic_string<_CharT, _Traits, _Allocator>::rfind(const _Tp& __t,
3567                                                size_type __pos) const _NOEXCEPT
3568{
3569    __self_view __sv = __t;
3570    return __str_rfind<value_type, size_type, traits_type, npos>
3571        (data(), size(), __sv.data(), __pos, __sv.size());
3572}
3573
3574template<class _CharT, class _Traits, class _Allocator>
3575inline
3576typename basic_string<_CharT, _Traits, _Allocator>::size_type
3577basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3578                                                 size_type __pos) const _NOEXCEPT
3579{
3580    _LIBCPP_ASSERT(__s != nullptr, "string::rfind(): received nullptr");
3581    return __str_rfind<value_type, size_type, traits_type, npos>
3582        (data(), size(), __s, __pos, traits_type::length(__s));
3583}
3584
3585template<class _CharT, class _Traits, class _Allocator>
3586typename basic_string<_CharT, _Traits, _Allocator>::size_type
3587basic_string<_CharT, _Traits, _Allocator>::rfind(value_type __c,
3588                                                 size_type __pos) const _NOEXCEPT
3589{
3590    return __str_rfind<value_type, size_type, traits_type, npos>
3591        (data(), size(), __c, __pos);
3592}
3593
3594// find_first_of
3595
3596template<class _CharT, class _Traits, class _Allocator>
3597typename basic_string<_CharT, _Traits, _Allocator>::size_type
3598basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3599                                                         size_type __pos,
3600                                                         size_type __n) const _NOEXCEPT
3601{
3602    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_of(): received nullptr");
3603    return __str_find_first_of<value_type, size_type, traits_type, npos>
3604        (data(), size(), __s, __pos, __n);
3605}
3606
3607template<class _CharT, class _Traits, class _Allocator>
3608inline
3609typename basic_string<_CharT, _Traits, _Allocator>::size_type
3610basic_string<_CharT, _Traits, _Allocator>::find_first_of(const basic_string& __str,
3611                                                         size_type __pos) const _NOEXCEPT
3612{
3613    return __str_find_first_of<value_type, size_type, traits_type, npos>
3614        (data(), size(), __str.data(), __pos, __str.size());
3615}
3616
3617template<class _CharT, class _Traits, class _Allocator>
3618template <class _Tp>
3619__enable_if_t
3620<
3621    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3622    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3623>
3624basic_string<_CharT, _Traits, _Allocator>::find_first_of(const _Tp& __t,
3625                                                size_type __pos) const _NOEXCEPT
3626{
3627    __self_view __sv = __t;
3628    return __str_find_first_of<value_type, size_type, traits_type, npos>
3629        (data(), size(), __sv.data(), __pos, __sv.size());
3630}
3631
3632template<class _CharT, class _Traits, class _Allocator>
3633inline
3634typename basic_string<_CharT, _Traits, _Allocator>::size_type
3635basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3636                                                         size_type __pos) const _NOEXCEPT
3637{
3638    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_of(): received nullptr");
3639    return __str_find_first_of<value_type, size_type, traits_type, npos>
3640        (data(), size(), __s, __pos, traits_type::length(__s));
3641}
3642
3643template<class _CharT, class _Traits, class _Allocator>
3644inline
3645typename basic_string<_CharT, _Traits, _Allocator>::size_type
3646basic_string<_CharT, _Traits, _Allocator>::find_first_of(value_type __c,
3647                                                         size_type __pos) const _NOEXCEPT
3648{
3649    return find(__c, __pos);
3650}
3651
3652// find_last_of
3653
3654template<class _CharT, class _Traits, class _Allocator>
3655typename basic_string<_CharT, _Traits, _Allocator>::size_type
3656basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3657                                                        size_type __pos,
3658                                                        size_type __n) const _NOEXCEPT
3659{
3660    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_of(): received nullptr");
3661    return __str_find_last_of<value_type, size_type, traits_type, npos>
3662        (data(), size(), __s, __pos, __n);
3663}
3664
3665template<class _CharT, class _Traits, class _Allocator>
3666inline
3667typename basic_string<_CharT, _Traits, _Allocator>::size_type
3668basic_string<_CharT, _Traits, _Allocator>::find_last_of(const basic_string& __str,
3669                                                        size_type __pos) const _NOEXCEPT
3670{
3671    return __str_find_last_of<value_type, size_type, traits_type, npos>
3672        (data(), size(), __str.data(), __pos, __str.size());
3673}
3674
3675template<class _CharT, class _Traits, class _Allocator>
3676template <class _Tp>
3677__enable_if_t
3678<
3679    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3680    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3681>
3682basic_string<_CharT, _Traits, _Allocator>::find_last_of(const _Tp& __t,
3683                                                size_type __pos) const _NOEXCEPT
3684{
3685    __self_view __sv = __t;
3686    return __str_find_last_of<value_type, size_type, traits_type, npos>
3687        (data(), size(), __sv.data(), __pos, __sv.size());
3688}
3689
3690template<class _CharT, class _Traits, class _Allocator>
3691inline
3692typename basic_string<_CharT, _Traits, _Allocator>::size_type
3693basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3694                                                        size_type __pos) const _NOEXCEPT
3695{
3696    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_of(): received nullptr");
3697    return __str_find_last_of<value_type, size_type, traits_type, npos>
3698        (data(), size(), __s, __pos, traits_type::length(__s));
3699}
3700
3701template<class _CharT, class _Traits, class _Allocator>
3702inline
3703typename basic_string<_CharT, _Traits, _Allocator>::size_type
3704basic_string<_CharT, _Traits, _Allocator>::find_last_of(value_type __c,
3705                                                        size_type __pos) const _NOEXCEPT
3706{
3707    return rfind(__c, __pos);
3708}
3709
3710// find_first_not_of
3711
3712template<class _CharT, class _Traits, class _Allocator>
3713typename basic_string<_CharT, _Traits, _Allocator>::size_type
3714basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3715                                                             size_type __pos,
3716                                                             size_type __n) const _NOEXCEPT
3717{
3718    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_not_of(): received nullptr");
3719    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3720        (data(), size(), __s, __pos, __n);
3721}
3722
3723template<class _CharT, class _Traits, class _Allocator>
3724inline
3725typename basic_string<_CharT, _Traits, _Allocator>::size_type
3726basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const basic_string& __str,
3727                                                             size_type __pos) const _NOEXCEPT
3728{
3729    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3730        (data(), size(), __str.data(), __pos, __str.size());
3731}
3732
3733template<class _CharT, class _Traits, class _Allocator>
3734template <class _Tp>
3735__enable_if_t
3736<
3737    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3738    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3739>
3740basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const _Tp& __t,
3741                                                size_type __pos) const _NOEXCEPT
3742{
3743    __self_view __sv = __t;
3744    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3745        (data(), size(), __sv.data(), __pos, __sv.size());
3746}
3747
3748template<class _CharT, class _Traits, class _Allocator>
3749inline
3750typename basic_string<_CharT, _Traits, _Allocator>::size_type
3751basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3752                                                             size_type __pos) const _NOEXCEPT
3753{
3754    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_not_of(): received nullptr");
3755    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3756        (data(), size(), __s, __pos, traits_type::length(__s));
3757}
3758
3759template<class _CharT, class _Traits, class _Allocator>
3760inline
3761typename basic_string<_CharT, _Traits, _Allocator>::size_type
3762basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(value_type __c,
3763                                                             size_type __pos) const _NOEXCEPT
3764{
3765    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3766        (data(), size(), __c, __pos);
3767}
3768
3769// find_last_not_of
3770
3771template<class _CharT, class _Traits, class _Allocator>
3772typename basic_string<_CharT, _Traits, _Allocator>::size_type
3773basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3774                                                            size_type __pos,
3775                                                            size_type __n) const _NOEXCEPT
3776{
3777    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_not_of(): received nullptr");
3778    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3779        (data(), size(), __s, __pos, __n);
3780}
3781
3782template<class _CharT, class _Traits, class _Allocator>
3783inline
3784typename basic_string<_CharT, _Traits, _Allocator>::size_type
3785basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const basic_string& __str,
3786                                                            size_type __pos) const _NOEXCEPT
3787{
3788    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3789        (data(), size(), __str.data(), __pos, __str.size());
3790}
3791
3792template<class _CharT, class _Traits, class _Allocator>
3793template <class _Tp>
3794__enable_if_t
3795<
3796    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3797    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3798>
3799basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const _Tp& __t,
3800                                                size_type __pos) const _NOEXCEPT
3801{
3802    __self_view __sv = __t;
3803    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3804        (data(), size(), __sv.data(), __pos, __sv.size());
3805}
3806
3807template<class _CharT, class _Traits, class _Allocator>
3808inline
3809typename basic_string<_CharT, _Traits, _Allocator>::size_type
3810basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3811                                                            size_type __pos) const _NOEXCEPT
3812{
3813    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_not_of(): received nullptr");
3814    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3815        (data(), size(), __s, __pos, traits_type::length(__s));
3816}
3817
3818template<class _CharT, class _Traits, class _Allocator>
3819inline
3820typename basic_string<_CharT, _Traits, _Allocator>::size_type
3821basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(value_type __c,
3822                                                            size_type __pos) const _NOEXCEPT
3823{
3824    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3825        (data(), size(), __c, __pos);
3826}
3827
3828// compare
3829
3830template <class _CharT, class _Traits, class _Allocator>
3831template <class _Tp>
3832__enable_if_t
3833<
3834    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3835    int
3836>
3837basic_string<_CharT, _Traits, _Allocator>::compare(const _Tp& __t) const _NOEXCEPT
3838{
3839    __self_view __sv = __t;
3840    size_t __lhs_sz = size();
3841    size_t __rhs_sz = __sv.size();
3842    int __result = traits_type::compare(data(), __sv.data(),
3843                                        _VSTD::min(__lhs_sz, __rhs_sz));
3844    if (__result != 0)
3845        return __result;
3846    if (__lhs_sz < __rhs_sz)
3847        return -1;
3848    if (__lhs_sz > __rhs_sz)
3849        return 1;
3850    return 0;
3851}
3852
3853template <class _CharT, class _Traits, class _Allocator>
3854inline
3855int
3856basic_string<_CharT, _Traits, _Allocator>::compare(const basic_string& __str) const _NOEXCEPT
3857{
3858    return compare(__self_view(__str));
3859}
3860
3861template <class _CharT, class _Traits, class _Allocator>
3862int
3863basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3864                                                   size_type __n1,
3865                                                   const value_type* __s,
3866                                                   size_type __n2) const
3867{
3868    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::compare(): received nullptr");
3869    size_type __sz = size();
3870    if (__pos1 > __sz || __n2 == npos)
3871        this->__throw_out_of_range();
3872    size_type __rlen = _VSTD::min(__n1, __sz - __pos1);
3873    int __r = traits_type::compare(data() + __pos1, __s, _VSTD::min(__rlen, __n2));
3874    if (__r == 0)
3875    {
3876        if (__rlen < __n2)
3877            __r = -1;
3878        else if (__rlen > __n2)
3879            __r = 1;
3880    }
3881    return __r;
3882}
3883
3884template <class _CharT, class _Traits, class _Allocator>
3885template <class _Tp>
3886__enable_if_t
3887<
3888    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3889    int
3890>
3891basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3892                                                   size_type __n1,
3893                                                   const _Tp& __t) const
3894{
3895    __self_view __sv = __t;
3896    return compare(__pos1, __n1, __sv.data(), __sv.size());
3897}
3898
3899template <class _CharT, class _Traits, class _Allocator>
3900inline
3901int
3902basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3903                                                   size_type __n1,
3904                                                   const basic_string& __str) const
3905{
3906    return compare(__pos1, __n1, __str.data(), __str.size());
3907}
3908
3909template <class _CharT, class _Traits, class _Allocator>
3910template <class _Tp>
3911__enable_if_t
3912<
3913    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
3914    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
3915    int
3916>
3917basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3918                                                   size_type __n1,
3919                                                   const _Tp& __t,
3920                                                   size_type __pos2,
3921                                                   size_type __n2) const
3922{
3923    __self_view __sv = __t;
3924    return __self_view(*this).substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
3925}
3926
3927template <class _CharT, class _Traits, class _Allocator>
3928int
3929basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3930                                                   size_type __n1,
3931                                                   const basic_string& __str,
3932                                                   size_type __pos2,
3933                                                   size_type __n2) const
3934{
3935        return compare(__pos1, __n1, __self_view(__str), __pos2, __n2);
3936}
3937
3938template <class _CharT, class _Traits, class _Allocator>
3939int
3940basic_string<_CharT, _Traits, _Allocator>::compare(const value_type* __s) const _NOEXCEPT
3941{
3942    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3943    return compare(0, npos, __s, traits_type::length(__s));
3944}
3945
3946template <class _CharT, class _Traits, class _Allocator>
3947int
3948basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3949                                                   size_type __n1,
3950                                                   const value_type* __s) const
3951{
3952    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3953    return compare(__pos1, __n1, __s, traits_type::length(__s));
3954}
3955
3956// __invariants
3957
3958template<class _CharT, class _Traits, class _Allocator>
3959inline
3960bool
3961basic_string<_CharT, _Traits, _Allocator>::__invariants() const
3962{
3963    if (size() > capacity())
3964        return false;
3965    if (capacity() < __min_cap - 1)
3966        return false;
3967    if (data() == nullptr)
3968        return false;
3969    if (data()[size()] != value_type())
3970        return false;
3971    return true;
3972}
3973
3974// __clear_and_shrink
3975
3976template<class _CharT, class _Traits, class _Allocator>
3977inline
3978void
3979basic_string<_CharT, _Traits, _Allocator>::__clear_and_shrink() _NOEXCEPT
3980{
3981    clear();
3982    if(__is_long())
3983    {
3984        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), capacity() + 1);
3985        __set_long_cap(0);
3986        __set_short_size(0);
3987        traits_type::assign(*__get_short_pointer(), value_type());
3988    }
3989}
3990
3991// operator==
3992
3993template<class _CharT, class _Traits, class _Allocator>
3994inline _LIBCPP_INLINE_VISIBILITY
3995bool
3996operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
3997           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3998{
3999    size_t __lhs_sz = __lhs.size();
4000    return __lhs_sz == __rhs.size() && _Traits::compare(__lhs.data(),
4001                                                        __rhs.data(),
4002                                                        __lhs_sz) == 0;
4003}
4004
4005template<class _Allocator>
4006inline _LIBCPP_INLINE_VISIBILITY
4007bool
4008operator==(const basic_string<char, char_traits<char>, _Allocator>& __lhs,
4009           const basic_string<char, char_traits<char>, _Allocator>& __rhs) _NOEXCEPT
4010{
4011    size_t __lhs_sz = __lhs.size();
4012    if (__lhs_sz != __rhs.size())
4013        return false;
4014    const char* __lp = __lhs.data();
4015    const char* __rp = __rhs.data();
4016    if (__lhs.__is_long())
4017        return char_traits<char>::compare(__lp, __rp, __lhs_sz) == 0;
4018    for (; __lhs_sz != 0; --__lhs_sz, ++__lp, ++__rp)
4019        if (*__lp != *__rp)
4020            return false;
4021    return true;
4022}
4023
4024template<class _CharT, class _Traits, class _Allocator>
4025inline _LIBCPP_INLINE_VISIBILITY
4026bool
4027operator==(const _CharT* __lhs,
4028           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4029{
4030    typedef basic_string<_CharT, _Traits, _Allocator> _String;
4031    _LIBCPP_ASSERT(__lhs != nullptr, "operator==(char*, basic_string): received nullptr");
4032    size_t __lhs_len = _Traits::length(__lhs);
4033    if (__lhs_len != __rhs.size()) return false;
4034    return __rhs.compare(0, _String::npos, __lhs, __lhs_len) == 0;
4035}
4036
4037template<class _CharT, class _Traits, class _Allocator>
4038inline _LIBCPP_INLINE_VISIBILITY
4039bool
4040operator==(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
4041           const _CharT* __rhs) _NOEXCEPT
4042{
4043    typedef basic_string<_CharT, _Traits, _Allocator> _String;
4044    _LIBCPP_ASSERT(__rhs != nullptr, "operator==(basic_string, char*): received nullptr");
4045    size_t __rhs_len = _Traits::length(__rhs);
4046    if (__rhs_len != __lhs.size()) return false;
4047    return __lhs.compare(0, _String::npos, __rhs, __rhs_len) == 0;
4048}
4049
4050template<class _CharT, class _Traits, class _Allocator>
4051inline _LIBCPP_INLINE_VISIBILITY
4052bool
4053operator!=(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
4054           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4055{
4056    return !(__lhs == __rhs);
4057}
4058
4059template<class _CharT, class _Traits, class _Allocator>
4060inline _LIBCPP_INLINE_VISIBILITY
4061bool
4062operator!=(const _CharT* __lhs,
4063           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4064{
4065    return !(__lhs == __rhs);
4066}
4067
4068template<class _CharT, class _Traits, class _Allocator>
4069inline _LIBCPP_INLINE_VISIBILITY
4070bool
4071operator!=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4072           const _CharT* __rhs) _NOEXCEPT
4073{
4074    return !(__lhs == __rhs);
4075}
4076
4077// operator<
4078
4079template<class _CharT, class _Traits, class _Allocator>
4080inline _LIBCPP_INLINE_VISIBILITY
4081bool
4082operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4083           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4084{
4085    return __lhs.compare(__rhs) < 0;
4086}
4087
4088template<class _CharT, class _Traits, class _Allocator>
4089inline _LIBCPP_INLINE_VISIBILITY
4090bool
4091operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4092           const _CharT* __rhs) _NOEXCEPT
4093{
4094    return __lhs.compare(__rhs) < 0;
4095}
4096
4097template<class _CharT, class _Traits, class _Allocator>
4098inline _LIBCPP_INLINE_VISIBILITY
4099bool
4100operator< (const _CharT* __lhs,
4101           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4102{
4103    return __rhs.compare(__lhs) > 0;
4104}
4105
4106// operator>
4107
4108template<class _CharT, class _Traits, class _Allocator>
4109inline _LIBCPP_INLINE_VISIBILITY
4110bool
4111operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4112           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4113{
4114    return __rhs < __lhs;
4115}
4116
4117template<class _CharT, class _Traits, class _Allocator>
4118inline _LIBCPP_INLINE_VISIBILITY
4119bool
4120operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4121           const _CharT* __rhs) _NOEXCEPT
4122{
4123    return __rhs < __lhs;
4124}
4125
4126template<class _CharT, class _Traits, class _Allocator>
4127inline _LIBCPP_INLINE_VISIBILITY
4128bool
4129operator> (const _CharT* __lhs,
4130           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4131{
4132    return __rhs < __lhs;
4133}
4134
4135// operator<=
4136
4137template<class _CharT, class _Traits, class _Allocator>
4138inline _LIBCPP_INLINE_VISIBILITY
4139bool
4140operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4141           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4142{
4143    return !(__rhs < __lhs);
4144}
4145
4146template<class _CharT, class _Traits, class _Allocator>
4147inline _LIBCPP_INLINE_VISIBILITY
4148bool
4149operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4150           const _CharT* __rhs) _NOEXCEPT
4151{
4152    return !(__rhs < __lhs);
4153}
4154
4155template<class _CharT, class _Traits, class _Allocator>
4156inline _LIBCPP_INLINE_VISIBILITY
4157bool
4158operator<=(const _CharT* __lhs,
4159           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4160{
4161    return !(__rhs < __lhs);
4162}
4163
4164// operator>=
4165
4166template<class _CharT, class _Traits, class _Allocator>
4167inline _LIBCPP_INLINE_VISIBILITY
4168bool
4169operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4170           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4171{
4172    return !(__lhs < __rhs);
4173}
4174
4175template<class _CharT, class _Traits, class _Allocator>
4176inline _LIBCPP_INLINE_VISIBILITY
4177bool
4178operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4179           const _CharT* __rhs) _NOEXCEPT
4180{
4181    return !(__lhs < __rhs);
4182}
4183
4184template<class _CharT, class _Traits, class _Allocator>
4185inline _LIBCPP_INLINE_VISIBILITY
4186bool
4187operator>=(const _CharT* __lhs,
4188           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4189{
4190    return !(__lhs < __rhs);
4191}
4192
4193// operator +
4194
4195template<class _CharT, class _Traits, class _Allocator>
4196basic_string<_CharT, _Traits, _Allocator>
4197operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4198          const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4199{
4200    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4201    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4202    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4203    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4204    __r.append(__rhs.data(), __rhs_sz);
4205    return __r;
4206}
4207
4208template<class _CharT, class _Traits, class _Allocator>
4209basic_string<_CharT, _Traits, _Allocator>
4210operator+(const _CharT* __lhs , const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4211{
4212    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4213    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = _Traits::length(__lhs);
4214    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4215    __r.__init(__lhs, __lhs_sz, __lhs_sz + __rhs_sz);
4216    __r.append(__rhs.data(), __rhs_sz);
4217    return __r;
4218}
4219
4220template<class _CharT, class _Traits, class _Allocator>
4221basic_string<_CharT, _Traits, _Allocator>
4222operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4223{
4224    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4225    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4226    __r.__init(&__lhs, 1, 1 + __rhs_sz);
4227    __r.append(__rhs.data(), __rhs_sz);
4228    return __r;
4229}
4230
4231template<class _CharT, class _Traits, class _Allocator>
4232inline
4233basic_string<_CharT, _Traits, _Allocator>
4234operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs)
4235{
4236    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4237    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4238    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = _Traits::length(__rhs);
4239    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4240    __r.append(__rhs, __rhs_sz);
4241    return __r;
4242}
4243
4244template<class _CharT, class _Traits, class _Allocator>
4245basic_string<_CharT, _Traits, _Allocator>
4246operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, _CharT __rhs)
4247{
4248    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4249    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4250    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + 1);
4251    __r.push_back(__rhs);
4252    return __r;
4253}
4254
4255#ifndef _LIBCPP_CXX03_LANG
4256
4257template<class _CharT, class _Traits, class _Allocator>
4258inline _LIBCPP_INLINE_VISIBILITY
4259basic_string<_CharT, _Traits, _Allocator>
4260operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4261{
4262    return _VSTD::move(__lhs.append(__rhs));
4263}
4264
4265template<class _CharT, class _Traits, class _Allocator>
4266inline _LIBCPP_INLINE_VISIBILITY
4267basic_string<_CharT, _Traits, _Allocator>
4268operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4269{
4270    return _VSTD::move(__rhs.insert(0, __lhs));
4271}
4272
4273template<class _CharT, class _Traits, class _Allocator>
4274inline _LIBCPP_INLINE_VISIBILITY
4275basic_string<_CharT, _Traits, _Allocator>
4276operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4277{
4278    return _VSTD::move(__lhs.append(__rhs));
4279}
4280
4281template<class _CharT, class _Traits, class _Allocator>
4282inline _LIBCPP_INLINE_VISIBILITY
4283basic_string<_CharT, _Traits, _Allocator>
4284operator+(const _CharT* __lhs , basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4285{
4286    return _VSTD::move(__rhs.insert(0, __lhs));
4287}
4288
4289template<class _CharT, class _Traits, class _Allocator>
4290inline _LIBCPP_INLINE_VISIBILITY
4291basic_string<_CharT, _Traits, _Allocator>
4292operator+(_CharT __lhs, basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4293{
4294    __rhs.insert(__rhs.begin(), __lhs);
4295    return _VSTD::move(__rhs);
4296}
4297
4298template<class _CharT, class _Traits, class _Allocator>
4299inline _LIBCPP_INLINE_VISIBILITY
4300basic_string<_CharT, _Traits, _Allocator>
4301operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const _CharT* __rhs)
4302{
4303    return _VSTD::move(__lhs.append(__rhs));
4304}
4305
4306template<class _CharT, class _Traits, class _Allocator>
4307inline _LIBCPP_INLINE_VISIBILITY
4308basic_string<_CharT, _Traits, _Allocator>
4309operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, _CharT __rhs)
4310{
4311    __lhs.push_back(__rhs);
4312    return _VSTD::move(__lhs);
4313}
4314
4315#endif // _LIBCPP_CXX03_LANG
4316
4317// swap
4318
4319template<class _CharT, class _Traits, class _Allocator>
4320inline _LIBCPP_INLINE_VISIBILITY
4321void
4322swap(basic_string<_CharT, _Traits, _Allocator>& __lhs,
4323     basic_string<_CharT, _Traits, _Allocator>& __rhs)
4324     _NOEXCEPT_(_NOEXCEPT_(__lhs.swap(__rhs)))
4325{
4326    __lhs.swap(__rhs);
4327}
4328
4329_LIBCPP_FUNC_VIS int                stoi  (const string& __str, size_t* __idx = nullptr, int __base = 10);
4330_LIBCPP_FUNC_VIS long               stol  (const string& __str, size_t* __idx = nullptr, int __base = 10);
4331_LIBCPP_FUNC_VIS unsigned long      stoul (const string& __str, size_t* __idx = nullptr, int __base = 10);
4332_LIBCPP_FUNC_VIS long long          stoll (const string& __str, size_t* __idx = nullptr, int __base = 10);
4333_LIBCPP_FUNC_VIS unsigned long long stoull(const string& __str, size_t* __idx = nullptr, int __base = 10);
4334
4335_LIBCPP_FUNC_VIS float       stof (const string& __str, size_t* __idx = nullptr);
4336_LIBCPP_FUNC_VIS double      stod (const string& __str, size_t* __idx = nullptr);
4337_LIBCPP_FUNC_VIS long double stold(const string& __str, size_t* __idx = nullptr);
4338
4339_LIBCPP_FUNC_VIS string to_string(int __val);
4340_LIBCPP_FUNC_VIS string to_string(unsigned __val);
4341_LIBCPP_FUNC_VIS string to_string(long __val);
4342_LIBCPP_FUNC_VIS string to_string(unsigned long __val);
4343_LIBCPP_FUNC_VIS string to_string(long long __val);
4344_LIBCPP_FUNC_VIS string to_string(unsigned long long __val);
4345_LIBCPP_FUNC_VIS string to_string(float __val);
4346_LIBCPP_FUNC_VIS string to_string(double __val);
4347_LIBCPP_FUNC_VIS string to_string(long double __val);
4348
4349#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
4350_LIBCPP_FUNC_VIS int                stoi  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4351_LIBCPP_FUNC_VIS long               stol  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4352_LIBCPP_FUNC_VIS unsigned long      stoul (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4353_LIBCPP_FUNC_VIS long long          stoll (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4354_LIBCPP_FUNC_VIS unsigned long long stoull(const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4355
4356_LIBCPP_FUNC_VIS float       stof (const wstring& __str, size_t* __idx = nullptr);
4357_LIBCPP_FUNC_VIS double      stod (const wstring& __str, size_t* __idx = nullptr);
4358_LIBCPP_FUNC_VIS long double stold(const wstring& __str, size_t* __idx = nullptr);
4359
4360_LIBCPP_FUNC_VIS wstring to_wstring(int __val);
4361_LIBCPP_FUNC_VIS wstring to_wstring(unsigned __val);
4362_LIBCPP_FUNC_VIS wstring to_wstring(long __val);
4363_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long __val);
4364_LIBCPP_FUNC_VIS wstring to_wstring(long long __val);
4365_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long long __val);
4366_LIBCPP_FUNC_VIS wstring to_wstring(float __val);
4367_LIBCPP_FUNC_VIS wstring to_wstring(double __val);
4368_LIBCPP_FUNC_VIS wstring to_wstring(long double __val);
4369#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
4370
4371template<class _CharT, class _Traits, class _Allocator>
4372_LIBCPP_TEMPLATE_DATA_VIS
4373const typename basic_string<_CharT, _Traits, _Allocator>::size_type
4374               basic_string<_CharT, _Traits, _Allocator>::npos;
4375
4376template <class _CharT, class _Allocator>
4377struct _LIBCPP_TEMPLATE_VIS
4378    hash<basic_string<_CharT, char_traits<_CharT>, _Allocator> >
4379    : public unary_function<
4380          basic_string<_CharT, char_traits<_CharT>, _Allocator>, size_t>
4381{
4382    size_t
4383    operator()(const basic_string<_CharT, char_traits<_CharT>, _Allocator>& __val) const _NOEXCEPT
4384    { return __do_string_hash(__val.data(), __val.data() + __val.size()); }
4385};
4386
4387
4388template<class _CharT, class _Traits, class _Allocator>
4389basic_ostream<_CharT, _Traits>&
4390operator<<(basic_ostream<_CharT, _Traits>& __os,
4391           const basic_string<_CharT, _Traits, _Allocator>& __str);
4392
4393template<class _CharT, class _Traits, class _Allocator>
4394basic_istream<_CharT, _Traits>&
4395operator>>(basic_istream<_CharT, _Traits>& __is,
4396           basic_string<_CharT, _Traits, _Allocator>& __str);
4397
4398template<class _CharT, class _Traits, class _Allocator>
4399basic_istream<_CharT, _Traits>&
4400getline(basic_istream<_CharT, _Traits>& __is,
4401        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4402
4403template<class _CharT, class _Traits, class _Allocator>
4404inline _LIBCPP_INLINE_VISIBILITY
4405basic_istream<_CharT, _Traits>&
4406getline(basic_istream<_CharT, _Traits>& __is,
4407        basic_string<_CharT, _Traits, _Allocator>& __str);
4408
4409template<class _CharT, class _Traits, class _Allocator>
4410inline _LIBCPP_INLINE_VISIBILITY
4411basic_istream<_CharT, _Traits>&
4412getline(basic_istream<_CharT, _Traits>&& __is,
4413        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4414
4415template<class _CharT, class _Traits, class _Allocator>
4416inline _LIBCPP_INLINE_VISIBILITY
4417basic_istream<_CharT, _Traits>&
4418getline(basic_istream<_CharT, _Traits>&& __is,
4419        basic_string<_CharT, _Traits, _Allocator>& __str);
4420
4421#if _LIBCPP_STD_VER > 17
4422template <class _CharT, class _Traits, class _Allocator, class _Up>
4423inline _LIBCPP_INLINE_VISIBILITY
4424    typename basic_string<_CharT, _Traits, _Allocator>::size_type
4425    erase(basic_string<_CharT, _Traits, _Allocator>& __str, const _Up& __v) {
4426  auto __old_size = __str.size();
4427  __str.erase(_VSTD::remove(__str.begin(), __str.end(), __v), __str.end());
4428  return __old_size - __str.size();
4429}
4430
4431template <class _CharT, class _Traits, class _Allocator, class _Predicate>
4432inline _LIBCPP_INLINE_VISIBILITY
4433    typename basic_string<_CharT, _Traits, _Allocator>::size_type
4434    erase_if(basic_string<_CharT, _Traits, _Allocator>& __str,
4435             _Predicate __pred) {
4436  auto __old_size = __str.size();
4437  __str.erase(_VSTD::remove_if(__str.begin(), __str.end(), __pred),
4438              __str.end());
4439  return __old_size - __str.size();
4440}
4441#endif
4442
4443#if _LIBCPP_DEBUG_LEVEL == 2
4444
4445template<class _CharT, class _Traits, class _Allocator>
4446bool
4447basic_string<_CharT, _Traits, _Allocator>::__dereferenceable(const const_iterator* __i) const
4448{
4449    return this->data() <= _VSTD::__to_address(__i->base()) &&
4450           _VSTD::__to_address(__i->base()) < this->data() + this->size();
4451}
4452
4453template<class _CharT, class _Traits, class _Allocator>
4454bool
4455basic_string<_CharT, _Traits, _Allocator>::__decrementable(const const_iterator* __i) const
4456{
4457    return this->data() < _VSTD::__to_address(__i->base()) &&
4458           _VSTD::__to_address(__i->base()) <= this->data() + this->size();
4459}
4460
4461template<class _CharT, class _Traits, class _Allocator>
4462bool
4463basic_string<_CharT, _Traits, _Allocator>::__addable(const const_iterator* __i, ptrdiff_t __n) const
4464{
4465    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4466    return this->data() <= __p && __p <= this->data() + this->size();
4467}
4468
4469template<class _CharT, class _Traits, class _Allocator>
4470bool
4471basic_string<_CharT, _Traits, _Allocator>::__subscriptable(const const_iterator* __i, ptrdiff_t __n) const
4472{
4473    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4474    return this->data() <= __p && __p < this->data() + this->size();
4475}
4476
4477#endif // _LIBCPP_DEBUG_LEVEL == 2
4478
4479#if _LIBCPP_STD_VER > 11
4480// Literal suffixes for basic_string [basic.string.literals]
4481inline namespace literals
4482{
4483  inline namespace string_literals
4484  {
4485    inline _LIBCPP_INLINE_VISIBILITY
4486    basic_string<char> operator "" s( const char *__str, size_t __len )
4487    {
4488        return basic_string<char> (__str, __len);
4489    }
4490
4491#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
4492    inline _LIBCPP_INLINE_VISIBILITY
4493    basic_string<wchar_t> operator "" s( const wchar_t *__str, size_t __len )
4494    {
4495        return basic_string<wchar_t> (__str, __len);
4496    }
4497#endif
4498
4499#ifndef _LIBCPP_HAS_NO_CHAR8_T
4500    inline _LIBCPP_INLINE_VISIBILITY
4501    basic_string<char8_t> operator "" s(const char8_t *__str, size_t __len) _NOEXCEPT
4502    {
4503        return basic_string<char8_t> (__str, __len);
4504    }
4505#endif
4506
4507    inline _LIBCPP_INLINE_VISIBILITY
4508    basic_string<char16_t> operator "" s( const char16_t *__str, size_t __len )
4509    {
4510        return basic_string<char16_t> (__str, __len);
4511    }
4512
4513    inline _LIBCPP_INLINE_VISIBILITY
4514    basic_string<char32_t> operator "" s( const char32_t *__str, size_t __len )
4515    {
4516        return basic_string<char32_t> (__str, __len);
4517    }
4518  } // namespace string_literals
4519} // namespace literals
4520#endif
4521
4522_LIBCPP_END_NAMESPACE_STD
4523
4524_LIBCPP_POP_MACROS
4525
4526#endif // _LIBCPP_STRING
4527