xref: /llvm-project-15.0.7/libcxx/include/string (revision 4e00a192)
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      pointer __data = data();
983      __erase_to_end(_VSTD::move(__op)(__data, __n));
984    }
985#endif
986
987    _LIBCPP_INLINE_VISIBILITY void __resize_default_init(size_type __n);
988
989    _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_INLINE_VISIBILITY
990    void reserve() _NOEXCEPT {shrink_to_fit();}
991    _LIBCPP_INLINE_VISIBILITY
992    void shrink_to_fit() _NOEXCEPT;
993    _LIBCPP_INLINE_VISIBILITY
994    void clear() _NOEXCEPT;
995    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
996    bool empty() const _NOEXCEPT {return size() == 0;}
997
998    _LIBCPP_INLINE_VISIBILITY const_reference operator[](size_type __pos) const _NOEXCEPT;
999    _LIBCPP_INLINE_VISIBILITY reference       operator[](size_type __pos)       _NOEXCEPT;
1000
1001    const_reference at(size_type __n) const;
1002    reference       at(size_type __n);
1003
1004    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const basic_string& __str) {return append(__str);}
1005
1006    template <class _Tp>
1007    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1008    __enable_if_t
1009        <
1010            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1011            && !__is_same_uncvref<_Tp, basic_string >::value,
1012            basic_string&
1013        >
1014                                            operator+=(const _Tp& __t)            {__self_view __sv = __t; return append(__sv);}
1015    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const value_type* __s)     {return append(__s);}
1016    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(value_type __c)            {push_back(__c); return *this;}
1017#ifndef _LIBCPP_CXX03_LANG
1018    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(initializer_list<value_type> __il) {return append(__il);}
1019#endif // _LIBCPP_CXX03_LANG
1020
1021    _LIBCPP_INLINE_VISIBILITY
1022    basic_string& append(const basic_string& __str);
1023
1024    template <class _Tp>
1025    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1026    __enable_if_t<
1027            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1028            && !__is_same_uncvref<_Tp, basic_string>::value,
1029            basic_string&
1030        >
1031                  append(const _Tp& __t) { __self_view __sv = __t; return append(__sv.data(), __sv.size()); }
1032    basic_string& append(const basic_string& __str, size_type __pos, size_type __n=npos);
1033
1034    template <class _Tp>
1035    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1036    __enable_if_t
1037        <
1038            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1039            && !__is_same_uncvref<_Tp, basic_string>::value,
1040            basic_string&
1041        >
1042                  append(const _Tp& __t, size_type __pos, size_type __n=npos);
1043    basic_string& append(const value_type* __s, size_type __n);
1044    basic_string& append(const value_type* __s);
1045    basic_string& append(size_type __n, value_type __c);
1046
1047    _LIBCPP_INLINE_VISIBILITY
1048    void __append_default_init(size_type __n);
1049
1050    template<class _InputIterator>
1051    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1052    __enable_if_t
1053        <
1054            __is_exactly_cpp17_input_iterator<_InputIterator>::value,
1055            basic_string&
1056        >
1057    _LIBCPP_INLINE_VISIBILITY
1058    append(_InputIterator __first, _InputIterator __last) {
1059      const basic_string __temp(__first, __last, __alloc());
1060      append(__temp.data(), __temp.size());
1061      return *this;
1062    }
1063    template<class _ForwardIterator>
1064    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1065    __enable_if_t
1066        <
1067            __is_cpp17_forward_iterator<_ForwardIterator>::value,
1068            basic_string&
1069        >
1070    _LIBCPP_INLINE_VISIBILITY
1071    append(_ForwardIterator __first, _ForwardIterator __last);
1072
1073#ifndef _LIBCPP_CXX03_LANG
1074    _LIBCPP_INLINE_VISIBILITY
1075    basic_string& append(initializer_list<value_type> __il) {return append(__il.begin(), __il.size());}
1076#endif // _LIBCPP_CXX03_LANG
1077
1078    void push_back(value_type __c);
1079    _LIBCPP_INLINE_VISIBILITY
1080    void pop_back();
1081    _LIBCPP_INLINE_VISIBILITY reference       front() _NOEXCEPT;
1082    _LIBCPP_INLINE_VISIBILITY const_reference front() const _NOEXCEPT;
1083    _LIBCPP_INLINE_VISIBILITY reference       back() _NOEXCEPT;
1084    _LIBCPP_INLINE_VISIBILITY const_reference back() const _NOEXCEPT;
1085
1086    template <class _Tp>
1087    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1088    __enable_if_t
1089        <
1090            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1091            basic_string&
1092        >
1093                 assign(const _Tp & __t) { __self_view __sv = __t; return assign(__sv.data(), __sv.size()); }
1094    _LIBCPP_INLINE_VISIBILITY
1095    basic_string& assign(const basic_string& __str) { return *this = __str; }
1096#ifndef _LIBCPP_CXX03_LANG
1097    _LIBCPP_INLINE_VISIBILITY
1098    basic_string& assign(basic_string&& __str)
1099        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
1100        {*this = _VSTD::move(__str); return *this;}
1101#endif
1102    basic_string& assign(const basic_string& __str, size_type __pos, size_type __n=npos);
1103    template <class _Tp>
1104    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1105    __enable_if_t
1106        <
1107            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1108            && !__is_same_uncvref<_Tp, basic_string>::value,
1109            basic_string&
1110        >
1111                  assign(const _Tp & __t, size_type __pos, size_type __n=npos);
1112    basic_string& assign(const value_type* __s, size_type __n);
1113    basic_string& assign(const value_type* __s);
1114    basic_string& assign(size_type __n, value_type __c);
1115    template<class _InputIterator>
1116    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1117    __enable_if_t
1118        <
1119            __is_exactly_cpp17_input_iterator<_InputIterator>::value,
1120            basic_string&
1121        >
1122        assign(_InputIterator __first, _InputIterator __last);
1123    template<class _ForwardIterator>
1124    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1125    __enable_if_t
1126        <
1127            __is_cpp17_forward_iterator<_ForwardIterator>::value,
1128            basic_string&
1129        >
1130        assign(_ForwardIterator __first, _ForwardIterator __last);
1131#ifndef _LIBCPP_CXX03_LANG
1132    _LIBCPP_INLINE_VISIBILITY
1133    basic_string& assign(initializer_list<value_type> __il) {return assign(__il.begin(), __il.size());}
1134#endif // _LIBCPP_CXX03_LANG
1135
1136    _LIBCPP_INLINE_VISIBILITY
1137    basic_string& insert(size_type __pos1, const basic_string& __str);
1138
1139    template <class _Tp>
1140    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1141    __enable_if_t
1142        <
1143            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1144            basic_string&
1145        >
1146                 insert(size_type __pos1, const _Tp& __t)
1147    { __self_view __sv = __t; return insert(__pos1, __sv.data(), __sv.size()); }
1148
1149    template <class _Tp>
1150    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1151    __enable_if_t
1152        <
1153            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value,
1154            basic_string&
1155        >
1156                  insert(size_type __pos1, const _Tp& __t, size_type __pos2, size_type __n=npos);
1157    basic_string& insert(size_type __pos1, const basic_string& __str, size_type __pos2, size_type __n=npos);
1158    basic_string& insert(size_type __pos, const value_type* __s, size_type __n);
1159    basic_string& insert(size_type __pos, const value_type* __s);
1160    basic_string& insert(size_type __pos, size_type __n, value_type __c);
1161    iterator      insert(const_iterator __pos, value_type __c);
1162    _LIBCPP_INLINE_VISIBILITY
1163    iterator      insert(const_iterator __pos, size_type __n, value_type __c);
1164    template<class _InputIterator>
1165    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1166    __enable_if_t
1167        <
1168            __is_exactly_cpp17_input_iterator<_InputIterator>::value,
1169            iterator
1170        >
1171        insert(const_iterator __pos, _InputIterator __first, _InputIterator __last);
1172    template<class _ForwardIterator>
1173    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1174    __enable_if_t
1175        <
1176            __is_cpp17_forward_iterator<_ForwardIterator>::value,
1177            iterator
1178        >
1179        insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last);
1180#ifndef _LIBCPP_CXX03_LANG
1181    _LIBCPP_INLINE_VISIBILITY
1182    iterator insert(const_iterator __pos, initializer_list<value_type> __il)
1183                    {return insert(__pos, __il.begin(), __il.end());}
1184#endif // _LIBCPP_CXX03_LANG
1185
1186    basic_string& erase(size_type __pos = 0, size_type __n = npos);
1187    _LIBCPP_INLINE_VISIBILITY
1188    iterator      erase(const_iterator __pos);
1189    _LIBCPP_INLINE_VISIBILITY
1190    iterator      erase(const_iterator __first, const_iterator __last);
1191
1192    _LIBCPP_INLINE_VISIBILITY
1193    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str);
1194
1195    template <class _Tp>
1196    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1197    __enable_if_t
1198        <
1199            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1200            basic_string&
1201        >
1202                  replace(size_type __pos1, size_type __n1, const _Tp& __t) { __self_view __sv = __t; return replace(__pos1, __n1, __sv.data(), __sv.size()); }
1203    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos);
1204    template <class _Tp>
1205    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1206    __enable_if_t
1207        <
1208            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
1209            basic_string&
1210        >
1211                  replace(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos);
1212    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2);
1213    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s);
1214    basic_string& replace(size_type __pos, size_type __n1, size_type __n2, value_type __c);
1215    _LIBCPP_INLINE_VISIBILITY
1216    basic_string& replace(const_iterator __i1, const_iterator __i2, const basic_string& __str);
1217
1218    template <class _Tp>
1219    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1220    __enable_if_t
1221        <
1222            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1223            basic_string&
1224        >
1225                  replace(const_iterator __i1, const_iterator __i2, const _Tp& __t) { __self_view __sv = __t; return replace(__i1 - begin(), __i2 - __i1, __sv); }
1226
1227    _LIBCPP_INLINE_VISIBILITY
1228    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n);
1229    _LIBCPP_INLINE_VISIBILITY
1230    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s);
1231    _LIBCPP_INLINE_VISIBILITY
1232    basic_string& replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c);
1233    template<class _InputIterator>
1234    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1235    __enable_if_t
1236        <
1237            __is_cpp17_input_iterator<_InputIterator>::value,
1238            basic_string&
1239        >
1240        replace(const_iterator __i1, const_iterator __i2, _InputIterator __j1, _InputIterator __j2);
1241#ifndef _LIBCPP_CXX03_LANG
1242    _LIBCPP_INLINE_VISIBILITY
1243    basic_string& replace(const_iterator __i1, const_iterator __i2, initializer_list<value_type> __il)
1244        {return replace(__i1, __i2, __il.begin(), __il.end());}
1245#endif // _LIBCPP_CXX03_LANG
1246
1247    size_type copy(value_type* __s, size_type __n, size_type __pos = 0) const;
1248    _LIBCPP_INLINE_VISIBILITY
1249    basic_string substr(size_type __pos = 0, size_type __n = npos) const;
1250
1251    _LIBCPP_INLINE_VISIBILITY
1252    void swap(basic_string& __str)
1253#if _LIBCPP_STD_VER >= 14
1254        _NOEXCEPT;
1255#else
1256        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
1257                    __is_nothrow_swappable<allocator_type>::value);
1258#endif
1259
1260    _LIBCPP_INLINE_VISIBILITY
1261    const value_type* c_str() const _NOEXCEPT {return data();}
1262    _LIBCPP_INLINE_VISIBILITY
1263    const value_type* data() const _NOEXCEPT  {return _VSTD::__to_address(__get_pointer());}
1264#if _LIBCPP_STD_VER > 14 || defined(_LIBCPP_BUILDING_LIBRARY)
1265    _LIBCPP_INLINE_VISIBILITY
1266    value_type* data()             _NOEXCEPT  {return _VSTD::__to_address(__get_pointer());}
1267#endif
1268
1269    _LIBCPP_INLINE_VISIBILITY
1270    allocator_type get_allocator() const _NOEXCEPT {return __alloc();}
1271
1272    _LIBCPP_INLINE_VISIBILITY
1273    size_type find(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1274
1275    template <class _Tp>
1276    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1277    __enable_if_t
1278        <
1279            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1280            size_type
1281        >
1282              find(const _Tp& __t, size_type __pos = 0) const _NOEXCEPT;
1283    size_type find(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1284    _LIBCPP_INLINE_VISIBILITY
1285    size_type find(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1286    size_type find(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1287
1288    _LIBCPP_INLINE_VISIBILITY
1289    size_type rfind(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1290
1291    template <class _Tp>
1292    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1293    __enable_if_t
1294        <
1295            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1296            size_type
1297        >
1298              rfind(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1299    size_type rfind(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1300    _LIBCPP_INLINE_VISIBILITY
1301    size_type rfind(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1302    size_type rfind(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1303
1304    _LIBCPP_INLINE_VISIBILITY
1305    size_type find_first_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1306
1307    template <class _Tp>
1308    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1309    __enable_if_t
1310        <
1311            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1312            size_type
1313        >
1314              find_first_of(const _Tp& __t, size_type __pos = 0) const _NOEXCEPT;
1315    size_type find_first_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1316    _LIBCPP_INLINE_VISIBILITY
1317    size_type find_first_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1318    _LIBCPP_INLINE_VISIBILITY
1319    size_type find_first_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1320
1321    _LIBCPP_INLINE_VISIBILITY
1322    size_type find_last_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1323
1324    template <class _Tp>
1325    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1326    __enable_if_t
1327        <
1328            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1329            size_type
1330        >
1331              find_last_of(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1332    size_type find_last_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1333    _LIBCPP_INLINE_VISIBILITY
1334    size_type find_last_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1335    _LIBCPP_INLINE_VISIBILITY
1336    size_type find_last_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1337
1338    _LIBCPP_INLINE_VISIBILITY
1339    size_type find_first_not_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1340
1341    template <class _Tp>
1342    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1343    __enable_if_t
1344        <
1345            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1346            size_type
1347        >
1348              find_first_not_of(const _Tp &__t, size_type __pos = 0) const _NOEXCEPT;
1349    size_type find_first_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1350    _LIBCPP_INLINE_VISIBILITY
1351    size_type find_first_not_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1352    _LIBCPP_INLINE_VISIBILITY
1353    size_type find_first_not_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1354
1355    _LIBCPP_INLINE_VISIBILITY
1356    size_type find_last_not_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1357
1358    template <class _Tp>
1359    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1360    __enable_if_t
1361        <
1362            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1363            size_type
1364        >
1365              find_last_not_of(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1366    size_type find_last_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1367    _LIBCPP_INLINE_VISIBILITY
1368    size_type find_last_not_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1369    _LIBCPP_INLINE_VISIBILITY
1370    size_type find_last_not_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1371
1372    _LIBCPP_INLINE_VISIBILITY
1373    int compare(const basic_string& __str) const _NOEXCEPT;
1374
1375    template <class _Tp>
1376    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1377    __enable_if_t
1378        <
1379            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1380            int
1381        >
1382        compare(const _Tp &__t) const _NOEXCEPT;
1383
1384    template <class _Tp>
1385    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1386    __enable_if_t
1387        <
1388            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1389            int
1390        >
1391         compare(size_type __pos1, size_type __n1, const _Tp& __t) const;
1392
1393    _LIBCPP_INLINE_VISIBILITY
1394    int compare(size_type __pos1, size_type __n1, const basic_string& __str) const;
1395    int compare(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos) const;
1396
1397    template <class _Tp>
1398    inline _LIBCPP_INLINE_VISIBILITY
1399        __enable_if_t
1400        <
1401            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
1402            int
1403        >
1404        compare(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos) const;
1405    int compare(const value_type* __s) const _NOEXCEPT;
1406    int compare(size_type __pos1, size_type __n1, const value_type* __s) const;
1407    int compare(size_type __pos1, size_type __n1, const value_type* __s, size_type __n2) const;
1408
1409#if _LIBCPP_STD_VER > 17
1410    constexpr _LIBCPP_INLINE_VISIBILITY
1411    bool starts_with(__self_view __sv) const noexcept
1412    { return __self_view(data(), size()).starts_with(__sv); }
1413
1414    constexpr _LIBCPP_INLINE_VISIBILITY
1415    bool starts_with(value_type __c) const noexcept
1416    { return !empty() && _Traits::eq(front(), __c); }
1417
1418    constexpr _LIBCPP_INLINE_VISIBILITY
1419    bool starts_with(const value_type* __s) const noexcept
1420    { return starts_with(__self_view(__s)); }
1421
1422    constexpr _LIBCPP_INLINE_VISIBILITY
1423    bool ends_with(__self_view __sv) const noexcept
1424    { return __self_view(data(), size()).ends_with( __sv); }
1425
1426    constexpr _LIBCPP_INLINE_VISIBILITY
1427    bool ends_with(value_type __c) const noexcept
1428    { return !empty() && _Traits::eq(back(), __c); }
1429
1430    constexpr _LIBCPP_INLINE_VISIBILITY
1431    bool ends_with(const value_type* __s) const noexcept
1432    { return ends_with(__self_view(__s)); }
1433#endif
1434
1435#if _LIBCPP_STD_VER > 20
1436    constexpr _LIBCPP_INLINE_VISIBILITY
1437    bool contains(__self_view __sv) const noexcept
1438    { return __self_view(data(), size()).contains(__sv); }
1439
1440    constexpr _LIBCPP_INLINE_VISIBILITY
1441    bool contains(value_type __c) const noexcept
1442    { return __self_view(data(), size()).contains(__c); }
1443
1444    constexpr _LIBCPP_INLINE_VISIBILITY
1445    bool contains(const value_type* __s) const
1446    { return __self_view(data(), size()).contains(__s); }
1447#endif
1448
1449    _LIBCPP_INLINE_VISIBILITY bool __invariants() const;
1450
1451    _LIBCPP_INLINE_VISIBILITY void __clear_and_shrink() _NOEXCEPT;
1452
1453    _LIBCPP_INLINE_VISIBILITY void __shrink_or_extend(size_type __target_capacity);
1454
1455    _LIBCPP_INLINE_VISIBILITY
1456    bool __is_long() const _NOEXCEPT
1457        {return bool(__r_.first().__s.__size_ & __short_mask);}
1458
1459#if _LIBCPP_DEBUG_LEVEL == 2
1460
1461    bool __dereferenceable(const const_iterator* __i) const;
1462    bool __decrementable(const const_iterator* __i) const;
1463    bool __addable(const const_iterator* __i, ptrdiff_t __n) const;
1464    bool __subscriptable(const const_iterator* __i, ptrdiff_t __n) const;
1465
1466#endif // _LIBCPP_DEBUG_LEVEL == 2
1467
1468private:
1469    _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI static bool __fits_in_sso(size_type __sz) {
1470        // SSO is disabled during constant evaluation because `__is_long` isn't constexpr friendly
1471        return !__libcpp_is_constant_evaluated() && (__sz < __min_cap);
1472    }
1473
1474    _LIBCPP_INLINE_VISIBILITY
1475    allocator_type& __alloc() _NOEXCEPT
1476        {return __r_.second();}
1477    _LIBCPP_INLINE_VISIBILITY
1478    const allocator_type& __alloc() const _NOEXCEPT
1479        {return __r_.second();}
1480
1481#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1482
1483    _LIBCPP_INLINE_VISIBILITY
1484    void __set_short_size(size_type __s) _NOEXCEPT
1485#   ifdef _LIBCPP_BIG_ENDIAN
1486        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
1487#   else
1488        {__r_.first().__s.__size_ = (unsigned char)(__s);}
1489#   endif
1490
1491    _LIBCPP_INLINE_VISIBILITY
1492    size_type __get_short_size() const _NOEXCEPT
1493#   ifdef _LIBCPP_BIG_ENDIAN
1494        {return __r_.first().__s.__size_ >> 1;}
1495#   else
1496        {return __r_.first().__s.__size_;}
1497#   endif
1498
1499#else  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1500
1501    _LIBCPP_INLINE_VISIBILITY
1502    void __set_short_size(size_type __s) _NOEXCEPT
1503#   ifdef _LIBCPP_BIG_ENDIAN
1504        {__r_.first().__s.__size_ = (unsigned char)(__s);}
1505#   else
1506        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
1507#   endif
1508
1509    _LIBCPP_INLINE_VISIBILITY
1510    size_type __get_short_size() const _NOEXCEPT
1511#   ifdef _LIBCPP_BIG_ENDIAN
1512        {return __r_.first().__s.__size_;}
1513#   else
1514        {return __r_.first().__s.__size_ >> 1;}
1515#   endif
1516
1517#endif // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1518
1519    _LIBCPP_INLINE_VISIBILITY
1520    void __set_long_size(size_type __s) _NOEXCEPT
1521        {__r_.first().__l.__size_ = __s;}
1522    _LIBCPP_INLINE_VISIBILITY
1523    size_type __get_long_size() const _NOEXCEPT
1524        {return __r_.first().__l.__size_;}
1525    _LIBCPP_INLINE_VISIBILITY
1526    void __set_size(size_type __s) _NOEXCEPT
1527        {if (__is_long()) __set_long_size(__s); else __set_short_size(__s);}
1528
1529    _LIBCPP_INLINE_VISIBILITY
1530    void __set_long_cap(size_type __s) _NOEXCEPT
1531        {__r_.first().__l.__cap_  = __long_mask | __s;}
1532    _LIBCPP_INLINE_VISIBILITY
1533    size_type __get_long_cap() const _NOEXCEPT
1534        {return __r_.first().__l.__cap_ & size_type(~__long_mask);}
1535
1536    _LIBCPP_INLINE_VISIBILITY
1537    void __set_long_pointer(pointer __p) _NOEXCEPT
1538        {__r_.first().__l.__data_ = __p;}
1539    _LIBCPP_INLINE_VISIBILITY
1540    pointer __get_long_pointer() _NOEXCEPT
1541        {return __r_.first().__l.__data_;}
1542    _LIBCPP_INLINE_VISIBILITY
1543    const_pointer __get_long_pointer() const _NOEXCEPT
1544        {return __r_.first().__l.__data_;}
1545    _LIBCPP_INLINE_VISIBILITY
1546    pointer __get_short_pointer() _NOEXCEPT
1547        {return pointer_traits<pointer>::pointer_to(__r_.first().__s.__data_[0]);}
1548    _LIBCPP_INLINE_VISIBILITY
1549    const_pointer __get_short_pointer() const _NOEXCEPT
1550        {return pointer_traits<const_pointer>::pointer_to(__r_.first().__s.__data_[0]);}
1551    _LIBCPP_INLINE_VISIBILITY
1552    pointer __get_pointer() _NOEXCEPT
1553        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
1554    _LIBCPP_INLINE_VISIBILITY
1555    const_pointer __get_pointer() const _NOEXCEPT
1556        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
1557
1558    _LIBCPP_INLINE_VISIBILITY
1559    void __zero() _NOEXCEPT
1560        {
1561            size_type (&__a)[__n_words] = __r_.first().__r.__words;
1562            for (unsigned __i = 0; __i < __n_words; ++__i)
1563                __a[__i] = 0;
1564        }
1565
1566    template <size_type __a> static
1567        _LIBCPP_INLINE_VISIBILITY
1568        size_type __align_it(size_type __s) _NOEXCEPT
1569            {return (__s + (__a-1)) & ~(__a-1);}
1570    enum {__alignment = 16};
1571    static _LIBCPP_INLINE_VISIBILITY
1572    size_type __recommend(size_type __s) _NOEXCEPT
1573        {
1574        if (__s < __min_cap) return static_cast<size_type>(__min_cap) - 1;
1575        size_type __guess = __align_it<sizeof(value_type) < __alignment ?
1576                     __alignment/sizeof(value_type) : 1 > (__s+1) - 1;
1577        if (__guess == __min_cap) ++__guess;
1578        return __guess;
1579        }
1580
1581    inline
1582    void __init(const value_type* __s, size_type __sz, size_type __reserve);
1583    inline
1584    void __init(const value_type* __s, size_type __sz);
1585    inline
1586    void __init(size_type __n, value_type __c);
1587
1588    // Slow path for the (inlined) copy constructor for 'long' strings.
1589    // Always externally instantiated and not inlined.
1590    // Requires that __s is zero terminated.
1591    // The main reason for this function to exist is because for unstable, we
1592    // want to allow inlining of the copy constructor. However, we don't want
1593    // to call the __init() functions as those are marked as inline which may
1594    // result in over-aggressive inlining by the compiler, where our aim is
1595    // to only inline the fast path code directly in the ctor.
1596    void __init_copy_ctor_external(const value_type* __s, size_type __sz);
1597
1598    template <class _InputIterator>
1599    inline
1600    __enable_if_t
1601    <
1602        __is_exactly_cpp17_input_iterator<_InputIterator>::value
1603    >
1604    __init(_InputIterator __first, _InputIterator __last);
1605
1606    template <class _ForwardIterator>
1607    inline
1608    __enable_if_t
1609    <
1610        __is_cpp17_forward_iterator<_ForwardIterator>::value
1611    >
1612    __init(_ForwardIterator __first, _ForwardIterator __last);
1613
1614    void __grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1615                   size_type __n_copy,  size_type __n_del,     size_type __n_add = 0);
1616    void __grow_by_and_replace(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1617                               size_type __n_copy,  size_type __n_del,
1618                               size_type __n_add, const value_type* __p_new_stuff);
1619
1620    // __assign_no_alias is invoked for assignment operations where we
1621    // have proof that the input does not alias the current instance.
1622    // For example, operator=(basic_string) performs a 'self' check.
1623    template <bool __is_short>
1624    basic_string& __assign_no_alias(const value_type* __s, size_type __n);
1625
1626    _LIBCPP_INLINE_VISIBILITY
1627    void __erase_to_end(size_type __pos);
1628
1629    // __erase_external_with_move is invoked for erase() invocations where
1630    // `n ~= npos`, likely requiring memory moves on the string data.
1631    void __erase_external_with_move(size_type __pos, size_type __n);
1632
1633    _LIBCPP_INLINE_VISIBILITY
1634    void __copy_assign_alloc(const basic_string& __str)
1635        {__copy_assign_alloc(__str, integral_constant<bool,
1636                      __alloc_traits::propagate_on_container_copy_assignment::value>());}
1637
1638    _LIBCPP_INLINE_VISIBILITY
1639    void __copy_assign_alloc(const basic_string& __str, true_type)
1640        {
1641            if (__alloc() == __str.__alloc())
1642                __alloc() = __str.__alloc();
1643            else
1644            {
1645                if (!__str.__is_long())
1646                {
1647                    __clear_and_shrink();
1648                    __alloc() = __str.__alloc();
1649                }
1650                else
1651                {
1652                    allocator_type __a = __str.__alloc();
1653                    pointer __p = __alloc_traits::allocate(__a, __str.__get_long_cap());
1654                    __clear_and_shrink();
1655                    __alloc() = _VSTD::move(__a);
1656                    __set_long_pointer(__p);
1657                    __set_long_cap(__str.__get_long_cap());
1658                    __set_long_size(__str.size());
1659                }
1660            }
1661        }
1662
1663    _LIBCPP_INLINE_VISIBILITY
1664    void __copy_assign_alloc(const basic_string&, false_type) _NOEXCEPT
1665        {}
1666
1667#ifndef _LIBCPP_CXX03_LANG
1668    _LIBCPP_INLINE_VISIBILITY
1669    void __move_assign(basic_string& __str, false_type)
1670        _NOEXCEPT_(__alloc_traits::is_always_equal::value);
1671    _LIBCPP_INLINE_VISIBILITY
1672    void __move_assign(basic_string& __str, true_type)
1673#if _LIBCPP_STD_VER > 14
1674        _NOEXCEPT;
1675#else
1676        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
1677#endif
1678#endif
1679
1680    _LIBCPP_INLINE_VISIBILITY
1681    void
1682    __move_assign_alloc(basic_string& __str)
1683        _NOEXCEPT_(
1684            !__alloc_traits::propagate_on_container_move_assignment::value ||
1685            is_nothrow_move_assignable<allocator_type>::value)
1686    {__move_assign_alloc(__str, integral_constant<bool,
1687                      __alloc_traits::propagate_on_container_move_assignment::value>());}
1688
1689    _LIBCPP_INLINE_VISIBILITY
1690    void __move_assign_alloc(basic_string& __c, true_type)
1691        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
1692        {
1693            __alloc() = _VSTD::move(__c.__alloc());
1694        }
1695
1696    _LIBCPP_INLINE_VISIBILITY
1697    void __move_assign_alloc(basic_string&, false_type)
1698        _NOEXCEPT
1699        {}
1700
1701    basic_string& __assign_external(const value_type* __s);
1702    basic_string& __assign_external(const value_type* __s, size_type __n);
1703
1704    // Assigns the value in __s, guaranteed to be __n < __min_cap in length.
1705    inline basic_string& __assign_short(const value_type* __s, size_type __n) {
1706      pointer __p = __is_long()
1707                        ? (__set_long_size(__n), __get_long_pointer())
1708                        : (__set_short_size(__n), __get_short_pointer());
1709      traits_type::move(_VSTD::__to_address(__p), __s, __n);
1710      traits_type::assign(__p[__n], value_type());
1711      return *this;
1712    }
1713
1714    _LIBCPP_HIDE_FROM_ABI basic_string& __null_terminate_at(value_type* __p, size_type __newsz) {
1715      __set_size(__newsz);
1716      __invalidate_iterators_past(__newsz);
1717      traits_type::assign(__p[__newsz], value_type());
1718      return *this;
1719    }
1720
1721    _LIBCPP_INLINE_VISIBILITY void __invalidate_all_iterators();
1722    _LIBCPP_INLINE_VISIBILITY void __invalidate_iterators_past(size_type);
1723
1724    template<class _Tp>
1725    _LIBCPP_INLINE_VISIBILITY
1726    bool __addr_in_range(_Tp&& __t) const {
1727        const volatile void *__p = _VSTD::addressof(__t);
1728        return data() <= __p && __p <= data() + size();
1729    }
1730
1731    _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI
1732    void __throw_length_error() const {
1733#ifndef _LIBCPP_NO_EXCEPTIONS
1734        __basic_string_common<true>::__throw_length_error();
1735#else
1736        _VSTD::abort();
1737#endif
1738    }
1739
1740    _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI
1741    void __throw_out_of_range() const {
1742#ifndef _LIBCPP_NO_EXCEPTIONS
1743        __basic_string_common<true>::__throw_out_of_range();
1744#else
1745        _VSTD::abort();
1746#endif
1747    }
1748
1749    friend basic_string operator+<>(const basic_string&, const basic_string&);
1750    friend basic_string operator+<>(const value_type*, const basic_string&);
1751    friend basic_string operator+<>(value_type, const basic_string&);
1752    friend basic_string operator+<>(const basic_string&, const value_type*);
1753    friend basic_string operator+<>(const basic_string&, value_type);
1754};
1755
1756// These declarations must appear before any functions are implicitly used
1757// so that they have the correct visibility specifier.
1758#ifdef _LIBCPP_ABI_STRING_OPTIMIZED_EXTERNAL_INSTANTIATION
1759    _LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
1760#   ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
1761        _LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
1762#   endif
1763#else
1764    _LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
1765#   ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
1766        _LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
1767#   endif
1768#endif
1769
1770
1771#if _LIBCPP_STD_VER >= 17
1772template<class _InputIterator,
1773         class _CharT = __iter_value_type<_InputIterator>,
1774         class _Allocator = allocator<_CharT>,
1775         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
1776         class = enable_if_t<__is_allocator<_Allocator>::value>
1777         >
1778basic_string(_InputIterator, _InputIterator, _Allocator = _Allocator())
1779  -> basic_string<_CharT, char_traits<_CharT>, _Allocator>;
1780
1781template<class _CharT,
1782         class _Traits,
1783         class _Allocator = allocator<_CharT>,
1784         class = enable_if_t<__is_allocator<_Allocator>::value>
1785         >
1786explicit basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
1787  -> basic_string<_CharT, _Traits, _Allocator>;
1788
1789template<class _CharT,
1790         class _Traits,
1791         class _Allocator = allocator<_CharT>,
1792         class = enable_if_t<__is_allocator<_Allocator>::value>,
1793         class _Sz = typename allocator_traits<_Allocator>::size_type
1794         >
1795basic_string(basic_string_view<_CharT, _Traits>, _Sz, _Sz, const _Allocator& = _Allocator())
1796  -> basic_string<_CharT, _Traits, _Allocator>;
1797#endif
1798
1799template <class _CharT, class _Traits, class _Allocator>
1800inline
1801void
1802basic_string<_CharT, _Traits, _Allocator>::__invalidate_all_iterators()
1803{
1804#if _LIBCPP_DEBUG_LEVEL == 2
1805    if (!__libcpp_is_constant_evaluated())
1806        __get_db()->__invalidate_all(this);
1807#endif
1808}
1809
1810template <class _CharT, class _Traits, class _Allocator>
1811inline
1812void
1813basic_string<_CharT, _Traits, _Allocator>::__invalidate_iterators_past(size_type __pos)
1814{
1815#if _LIBCPP_DEBUG_LEVEL == 2
1816    if (!__libcpp_is_constant_evaluated()) {
1817        __c_node* __c = __get_db()->__find_c_and_lock(this);
1818        if (__c)
1819        {
1820            const_pointer __new_last = __get_pointer() + __pos;
1821            for (__i_node** __p = __c->end_; __p != __c->beg_; )
1822            {
1823                --__p;
1824                const_iterator* __i = static_cast<const_iterator*>((*__p)->__i_);
1825                if (__i->base() > __new_last)
1826                {
1827                    (*__p)->__c_ = nullptr;
1828                    if (--__c->end_ != __p)
1829                        _VSTD::memmove(__p, __p+1, (__c->end_ - __p)*sizeof(__i_node*));
1830                }
1831            }
1832            __get_db()->unlock();
1833        }
1834    }
1835#else
1836    (void)__pos;
1837#endif // _LIBCPP_DEBUG_LEVEL == 2
1838}
1839
1840template <class _CharT, class _Traits, class _Allocator>
1841inline
1842basic_string<_CharT, _Traits, _Allocator>::basic_string()
1843    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
1844     : __r_(__default_init_tag(), __default_init_tag())
1845{
1846    _VSTD::__debug_db_insert_c(this);
1847    __zero();
1848}
1849
1850template <class _CharT, class _Traits, class _Allocator>
1851inline
1852basic_string<_CharT, _Traits, _Allocator>::basic_string(const allocator_type& __a)
1853#if _LIBCPP_STD_VER <= 14
1854        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value)
1855#else
1856        _NOEXCEPT
1857#endif
1858: __r_(__default_init_tag(), __a)
1859{
1860    _VSTD::__debug_db_insert_c(this);
1861    __zero();
1862}
1863
1864template <class _CharT, class _Traits, class _Allocator>
1865void basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s,
1866                                                       size_type __sz,
1867                                                       size_type __reserve)
1868{
1869    if (__reserve > max_size())
1870        this->__throw_length_error();
1871    pointer __p;
1872    if (__fits_in_sso(__reserve))
1873    {
1874        __set_short_size(__sz);
1875        __p = __get_short_pointer();
1876    }
1877    else
1878    {
1879        size_type __cap = __recommend(__reserve);
1880        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1881        __set_long_pointer(__p);
1882        __set_long_cap(__cap+1);
1883        __set_long_size(__sz);
1884    }
1885    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1886    traits_type::assign(__p[__sz], value_type());
1887}
1888
1889template <class _CharT, class _Traits, class _Allocator>
1890void
1891basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s, size_type __sz)
1892{
1893    if (__sz > max_size())
1894        this->__throw_length_error();
1895    pointer __p;
1896    if (__fits_in_sso(__sz))
1897    {
1898        __set_short_size(__sz);
1899        __p = __get_short_pointer();
1900    }
1901    else
1902    {
1903        size_type __cap = __recommend(__sz);
1904        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1905        __set_long_pointer(__p);
1906        __set_long_cap(__cap+1);
1907        __set_long_size(__sz);
1908    }
1909    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1910    traits_type::assign(__p[__sz], value_type());
1911}
1912
1913template <class _CharT, class _Traits, class _Allocator>
1914template <class>
1915basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, const _Allocator& __a)
1916    : __r_(__default_init_tag(), __a)
1917{
1918    _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*, allocator) detected nullptr");
1919    __init(__s, traits_type::length(__s));
1920    _VSTD::__debug_db_insert_c(this);
1921}
1922
1923template <class _CharT, class _Traits, class _Allocator>
1924inline
1925basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n)
1926     : __r_(__default_init_tag(), __default_init_tag())
1927{
1928    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n) detected nullptr");
1929    __init(__s, __n);
1930    _VSTD::__debug_db_insert_c(this);
1931}
1932
1933template <class _CharT, class _Traits, class _Allocator>
1934inline
1935basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n, const _Allocator& __a)
1936    : __r_(__default_init_tag(), __a)
1937{
1938    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n, allocator) detected nullptr");
1939    __init(__s, __n);
1940    _VSTD::__debug_db_insert_c(this);
1941}
1942
1943template <class _CharT, class _Traits, class _Allocator>
1944basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str)
1945    : __r_(__default_init_tag(), __alloc_traits::select_on_container_copy_construction(__str.__alloc()))
1946{
1947    if (!__str.__is_long())
1948        __r_.first().__r = __str.__r_.first().__r;
1949    else
1950        __init_copy_ctor_external(_VSTD::__to_address(__str.__get_long_pointer()),
1951                                  __str.__get_long_size());
1952    _VSTD::__debug_db_insert_c(this);
1953}
1954
1955template <class _CharT, class _Traits, class _Allocator>
1956basic_string<_CharT, _Traits, _Allocator>::basic_string(
1957    const basic_string& __str, const allocator_type& __a)
1958    : __r_(__default_init_tag(), __a)
1959{
1960    if (!__str.__is_long())
1961        __r_.first().__r = __str.__r_.first().__r;
1962    else
1963        __init_copy_ctor_external(_VSTD::__to_address(__str.__get_long_pointer()),
1964                                  __str.__get_long_size());
1965    _VSTD::__debug_db_insert_c(this);
1966}
1967
1968template <class _CharT, class _Traits, class _Allocator>
1969void basic_string<_CharT, _Traits, _Allocator>::__init_copy_ctor_external(
1970    const value_type* __s, size_type __sz) {
1971  pointer __p;
1972  if (__fits_in_sso(__sz)) {
1973    __p = __get_short_pointer();
1974    __set_short_size(__sz);
1975  } else {
1976    if (__sz > max_size())
1977      this->__throw_length_error();
1978    size_t __cap = __recommend(__sz);
1979    __p = __alloc_traits::allocate(__alloc(), __cap + 1);
1980    __set_long_pointer(__p);
1981    __set_long_cap(__cap + 1);
1982    __set_long_size(__sz);
1983  }
1984  traits_type::copy(_VSTD::__to_address(__p), __s, __sz + 1);
1985}
1986
1987#ifndef _LIBCPP_CXX03_LANG
1988
1989template <class _CharT, class _Traits, class _Allocator>
1990inline
1991basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str)
1992#if _LIBCPP_STD_VER <= 14
1993        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
1994#else
1995        _NOEXCEPT
1996#endif
1997    : __r_(_VSTD::move(__str.__r_))
1998{
1999    __str.__zero();
2000    _VSTD::__debug_db_insert_c(this);
2001#if _LIBCPP_DEBUG_LEVEL == 2
2002    if (!__libcpp_is_constant_evaluated() && __is_long())
2003        __get_db()->swap(this, &__str);
2004#endif
2005}
2006
2007template <class _CharT, class _Traits, class _Allocator>
2008inline
2009basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str, const allocator_type& __a)
2010    : __r_(__default_init_tag(), __a)
2011{
2012    if (__str.__is_long() && __a != __str.__alloc()) // copy, not move
2013        __init(_VSTD::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
2014    else
2015    {
2016        __r_.first().__r = __str.__r_.first().__r;
2017        __str.__zero();
2018    }
2019    _VSTD::__debug_db_insert_c(this);
2020#if _LIBCPP_DEBUG_LEVEL == 2
2021    if (!__libcpp_is_constant_evaluated() && __is_long())
2022        __get_db()->swap(this, &__str);
2023#endif
2024}
2025
2026#endif // _LIBCPP_CXX03_LANG
2027
2028template <class _CharT, class _Traits, class _Allocator>
2029void
2030basic_string<_CharT, _Traits, _Allocator>::__init(size_type __n, value_type __c)
2031{
2032    if (__n > max_size())
2033        this->__throw_length_error();
2034    pointer __p;
2035    if (__fits_in_sso(__n))
2036    {
2037        __set_short_size(__n);
2038        __p = __get_short_pointer();
2039    }
2040    else
2041    {
2042        size_type __cap = __recommend(__n);
2043        __p = __alloc_traits::allocate(__alloc(), __cap+1);
2044        __set_long_pointer(__p);
2045        __set_long_cap(__cap+1);
2046        __set_long_size(__n);
2047    }
2048    traits_type::assign(_VSTD::__to_address(__p), __n, __c);
2049    traits_type::assign(__p[__n], value_type());
2050}
2051
2052template <class _CharT, class _Traits, class _Allocator>
2053inline
2054basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c)
2055     : __r_(__default_init_tag(), __default_init_tag())
2056{
2057    __init(__n, __c);
2058    _VSTD::__debug_db_insert_c(this);
2059}
2060
2061template <class _CharT, class _Traits, class _Allocator>
2062template <class>
2063basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c, const _Allocator& __a)
2064    : __r_(__default_init_tag(), __a)
2065{
2066    __init(__n, __c);
2067    _VSTD::__debug_db_insert_c(this);
2068}
2069
2070template <class _CharT, class _Traits, class _Allocator>
2071basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str,
2072                                                        size_type __pos, size_type __n,
2073                                                        const _Allocator& __a)
2074    : __r_(__default_init_tag(), __a)
2075{
2076    size_type __str_sz = __str.size();
2077    if (__pos > __str_sz)
2078        this->__throw_out_of_range();
2079    __init(__str.data() + __pos, _VSTD::min(__n, __str_sz - __pos));
2080    _VSTD::__debug_db_insert_c(this);
2081}
2082
2083template <class _CharT, class _Traits, class _Allocator>
2084inline
2085basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str, size_type __pos,
2086                                                        const _Allocator& __a)
2087    : __r_(__default_init_tag(), __a)
2088{
2089    size_type __str_sz = __str.size();
2090    if (__pos > __str_sz)
2091        this->__throw_out_of_range();
2092    __init(__str.data() + __pos, __str_sz - __pos);
2093    _VSTD::__debug_db_insert_c(this);
2094}
2095
2096template <class _CharT, class _Traits, class _Allocator>
2097template <class _Tp, class>
2098basic_string<_CharT, _Traits, _Allocator>::basic_string(
2099             const _Tp& __t, size_type __pos, size_type __n, const allocator_type& __a)
2100    : __r_(__default_init_tag(), __a)
2101{
2102    __self_view __sv0 = __t;
2103    __self_view __sv = __sv0.substr(__pos, __n);
2104    __init(__sv.data(), __sv.size());
2105    _VSTD::__debug_db_insert_c(this);
2106}
2107
2108template <class _CharT, class _Traits, class _Allocator>
2109template <class _Tp, class>
2110basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t)
2111     : __r_(__default_init_tag(), __default_init_tag())
2112{
2113    __self_view __sv = __t;
2114    __init(__sv.data(), __sv.size());
2115    _VSTD::__debug_db_insert_c(this);
2116}
2117
2118template <class _CharT, class _Traits, class _Allocator>
2119template <class _Tp, class>
2120basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t, const _Allocator& __a)
2121    : __r_(__default_init_tag(), __a)
2122{
2123    __self_view __sv = __t;
2124    __init(__sv.data(), __sv.size());
2125    _VSTD::__debug_db_insert_c(this);
2126}
2127
2128template <class _CharT, class _Traits, class _Allocator>
2129template <class _InputIterator>
2130__enable_if_t
2131<
2132    __is_exactly_cpp17_input_iterator<_InputIterator>::value
2133>
2134basic_string<_CharT, _Traits, _Allocator>::__init(_InputIterator __first, _InputIterator __last)
2135{
2136    __zero();
2137#ifndef _LIBCPP_NO_EXCEPTIONS
2138    try
2139    {
2140#endif // _LIBCPP_NO_EXCEPTIONS
2141    for (; __first != __last; ++__first)
2142        push_back(*__first);
2143#ifndef _LIBCPP_NO_EXCEPTIONS
2144    }
2145    catch (...)
2146    {
2147        if (__is_long())
2148            __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2149        throw;
2150    }
2151#endif // _LIBCPP_NO_EXCEPTIONS
2152}
2153
2154template <class _CharT, class _Traits, class _Allocator>
2155template <class _ForwardIterator>
2156__enable_if_t
2157<
2158    __is_cpp17_forward_iterator<_ForwardIterator>::value
2159>
2160basic_string<_CharT, _Traits, _Allocator>::__init(_ForwardIterator __first, _ForwardIterator __last)
2161{
2162    size_type __sz = static_cast<size_type>(_VSTD::distance(__first, __last));
2163    if (__sz > max_size())
2164        this->__throw_length_error();
2165    pointer __p;
2166    if (__fits_in_sso(__sz))
2167    {
2168        __set_short_size(__sz);
2169        __p = __get_short_pointer();
2170    }
2171    else
2172    {
2173        size_type __cap = __recommend(__sz);
2174        __p = __alloc_traits::allocate(__alloc(), __cap+1);
2175        __set_long_pointer(__p);
2176        __set_long_cap(__cap+1);
2177        __set_long_size(__sz);
2178    }
2179
2180#ifndef _LIBCPP_NO_EXCEPTIONS
2181    try
2182    {
2183#endif  // _LIBCPP_NO_EXCEPTIONS
2184    for (; __first != __last; ++__first, (void) ++__p)
2185        traits_type::assign(*__p, *__first);
2186    traits_type::assign(*__p, value_type());
2187#ifndef _LIBCPP_NO_EXCEPTIONS
2188    }
2189    catch (...)
2190    {
2191        if (__is_long())
2192            __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2193        throw;
2194    }
2195#endif  // _LIBCPP_NO_EXCEPTIONS
2196}
2197
2198template <class _CharT, class _Traits, class _Allocator>
2199template<class _InputIterator, class>
2200inline
2201basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last)
2202     : __r_(__default_init_tag(), __default_init_tag())
2203{
2204    __init(__first, __last);
2205    _VSTD::__debug_db_insert_c(this);
2206}
2207
2208template <class _CharT, class _Traits, class _Allocator>
2209template<class _InputIterator, class>
2210inline
2211basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last,
2212                                                        const allocator_type& __a)
2213    : __r_(__default_init_tag(), __a)
2214{
2215    __init(__first, __last);
2216    _VSTD::__debug_db_insert_c(this);
2217}
2218
2219#ifndef _LIBCPP_CXX03_LANG
2220
2221template <class _CharT, class _Traits, class _Allocator>
2222inline
2223basic_string<_CharT, _Traits, _Allocator>::basic_string(
2224    initializer_list<_CharT> __il)
2225     : __r_(__default_init_tag(), __default_init_tag())
2226{
2227    __init(__il.begin(), __il.end());
2228    _VSTD::__debug_db_insert_c(this);
2229}
2230
2231template <class _CharT, class _Traits, class _Allocator>
2232inline
2233
2234basic_string<_CharT, _Traits, _Allocator>::basic_string(
2235    initializer_list<_CharT> __il, const _Allocator& __a)
2236    : __r_(__default_init_tag(), __a)
2237{
2238    __init(__il.begin(), __il.end());
2239    _VSTD::__debug_db_insert_c(this);
2240}
2241
2242#endif // _LIBCPP_CXX03_LANG
2243
2244template <class _CharT, class _Traits, class _Allocator>
2245basic_string<_CharT, _Traits, _Allocator>::~basic_string()
2246{
2247#if _LIBCPP_DEBUG_LEVEL == 2
2248    if (!__libcpp_is_constant_evaluated())
2249        __get_db()->__erase_c(this);
2250#endif
2251    if (__is_long())
2252        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2253}
2254
2255template <class _CharT, class _Traits, class _Allocator>
2256void
2257basic_string<_CharT, _Traits, _Allocator>::__grow_by_and_replace
2258    (size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2259     size_type __n_copy,  size_type __n_del,     size_type __n_add, const value_type* __p_new_stuff)
2260{
2261    size_type __ms = max_size();
2262    if (__delta_cap > __ms - __old_cap - 1)
2263        this->__throw_length_error();
2264    pointer __old_p = __get_pointer();
2265    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2266                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2267                          __ms - 1;
2268    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2269    __invalidate_all_iterators();
2270    if (__n_copy != 0)
2271        traits_type::copy(_VSTD::__to_address(__p),
2272                          _VSTD::__to_address(__old_p), __n_copy);
2273    if (__n_add != 0)
2274        traits_type::copy(_VSTD::__to_address(__p) + __n_copy, __p_new_stuff, __n_add);
2275    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2276    if (__sec_cp_sz != 0)
2277        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2278                          _VSTD::__to_address(__old_p) + __n_copy + __n_del, __sec_cp_sz);
2279    if (__old_cap+1 != __min_cap)
2280        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2281    __set_long_pointer(__p);
2282    __set_long_cap(__cap+1);
2283    __old_sz = __n_copy + __n_add + __sec_cp_sz;
2284    __set_long_size(__old_sz);
2285    traits_type::assign(__p[__old_sz], value_type());
2286}
2287
2288template <class _CharT, class _Traits, class _Allocator>
2289void
2290basic_string<_CharT, _Traits, _Allocator>::__grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2291                                                     size_type __n_copy,  size_type __n_del,     size_type __n_add)
2292{
2293    size_type __ms = max_size();
2294    if (__delta_cap > __ms - __old_cap)
2295        this->__throw_length_error();
2296    pointer __old_p = __get_pointer();
2297    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2298                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2299                          __ms - 1;
2300    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2301    __invalidate_all_iterators();
2302    if (__n_copy != 0)
2303        traits_type::copy(_VSTD::__to_address(__p),
2304                          _VSTD::__to_address(__old_p), __n_copy);
2305    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2306    if (__sec_cp_sz != 0)
2307        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2308                          _VSTD::__to_address(__old_p) + __n_copy + __n_del,
2309                          __sec_cp_sz);
2310    if (__old_cap+1 != __min_cap)
2311        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2312    __set_long_pointer(__p);
2313    __set_long_cap(__cap+1);
2314}
2315
2316// assign
2317
2318template <class _CharT, class _Traits, class _Allocator>
2319template <bool __is_short>
2320basic_string<_CharT, _Traits, _Allocator>&
2321basic_string<_CharT, _Traits, _Allocator>::__assign_no_alias(
2322    const value_type* __s, size_type __n) {
2323  size_type __cap = __is_short ? __min_cap : __get_long_cap();
2324  if (__n < __cap) {
2325    pointer __p = __is_short ? __get_short_pointer() : __get_long_pointer();
2326    __is_short ? __set_short_size(__n) : __set_long_size(__n);
2327    traits_type::copy(_VSTD::__to_address(__p), __s, __n);
2328    traits_type::assign(__p[__n], value_type());
2329    __invalidate_iterators_past(__n);
2330  } else {
2331    size_type __sz = __is_short ? __get_short_size() : __get_long_size();
2332    __grow_by_and_replace(__cap - 1, __n - __cap + 1, __sz, 0, __sz, __n, __s);
2333  }
2334  return *this;
2335}
2336
2337template <class _CharT, class _Traits, class _Allocator>
2338basic_string<_CharT, _Traits, _Allocator>&
2339basic_string<_CharT, _Traits, _Allocator>::__assign_external(
2340    const value_type* __s, size_type __n) {
2341  size_type __cap = capacity();
2342  if (__cap >= __n) {
2343    value_type* __p = _VSTD::__to_address(__get_pointer());
2344    traits_type::move(__p, __s, __n);
2345    return __null_terminate_at(__p, __n);
2346  } else {
2347    size_type __sz = size();
2348    __grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s);
2349    return *this;
2350  }
2351}
2352
2353template <class _CharT, class _Traits, class _Allocator>
2354basic_string<_CharT, _Traits, _Allocator>&
2355basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s, size_type __n)
2356{
2357    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::assign received nullptr");
2358    return (__builtin_constant_p(__n) && __fits_in_sso(__n))
2359               ? __assign_short(__s, __n)
2360               : __assign_external(__s, __n);
2361}
2362
2363template <class _CharT, class _Traits, class _Allocator>
2364basic_string<_CharT, _Traits, _Allocator>&
2365basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
2366{
2367    size_type __cap = capacity();
2368    if (__cap < __n)
2369    {
2370        size_type __sz = size();
2371        __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2372    }
2373    value_type* __p = _VSTD::__to_address(__get_pointer());
2374    traits_type::assign(__p, __n, __c);
2375    return __null_terminate_at(__p, __n);
2376}
2377
2378template <class _CharT, class _Traits, class _Allocator>
2379basic_string<_CharT, _Traits, _Allocator>&
2380basic_string<_CharT, _Traits, _Allocator>::operator=(value_type __c)
2381{
2382    pointer __p;
2383    if (__is_long())
2384    {
2385        __p = __get_long_pointer();
2386        __set_long_size(1);
2387    }
2388    else
2389    {
2390        __p = __get_short_pointer();
2391        __set_short_size(1);
2392    }
2393    traits_type::assign(*__p, __c);
2394    traits_type::assign(*++__p, value_type());
2395    __invalidate_iterators_past(1);
2396    return *this;
2397}
2398
2399template <class _CharT, class _Traits, class _Allocator>
2400basic_string<_CharT, _Traits, _Allocator>&
2401basic_string<_CharT, _Traits, _Allocator>::operator=(const basic_string& __str)
2402{
2403  if (this != &__str) {
2404    __copy_assign_alloc(__str);
2405    if (!__is_long()) {
2406      if (!__str.__is_long()) {
2407        __r_.first().__r = __str.__r_.first().__r;
2408      } else {
2409        return __assign_no_alias<true>(__str.data(), __str.size());
2410      }
2411    } else {
2412      return __assign_no_alias<false>(__str.data(), __str.size());
2413    }
2414  }
2415  return *this;
2416}
2417
2418#ifndef _LIBCPP_CXX03_LANG
2419
2420template <class _CharT, class _Traits, class _Allocator>
2421inline
2422void
2423basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, false_type)
2424    _NOEXCEPT_(__alloc_traits::is_always_equal::value)
2425{
2426    if (__alloc() != __str.__alloc())
2427        assign(__str);
2428    else
2429        __move_assign(__str, true_type());
2430}
2431
2432template <class _CharT, class _Traits, class _Allocator>
2433inline
2434void
2435basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, true_type)
2436#if _LIBCPP_STD_VER > 14
2437    _NOEXCEPT
2438#else
2439    _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
2440#endif
2441{
2442  if (__is_long()) {
2443    __alloc_traits::deallocate(__alloc(), __get_long_pointer(),
2444                               __get_long_cap());
2445#if _LIBCPP_STD_VER <= 14
2446    if (!is_nothrow_move_assignable<allocator_type>::value) {
2447      __set_short_size(0);
2448      traits_type::assign(__get_short_pointer()[0], value_type());
2449    }
2450#endif
2451  }
2452  __move_assign_alloc(__str);
2453  __r_.first() = __str.__r_.first();
2454  __str.__set_short_size(0);
2455  traits_type::assign(__str.__get_short_pointer()[0], value_type());
2456}
2457
2458template <class _CharT, class _Traits, class _Allocator>
2459inline
2460basic_string<_CharT, _Traits, _Allocator>&
2461basic_string<_CharT, _Traits, _Allocator>::operator=(basic_string&& __str)
2462    _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
2463{
2464    __move_assign(__str, integral_constant<bool,
2465          __alloc_traits::propagate_on_container_move_assignment::value>());
2466    return *this;
2467}
2468
2469#endif
2470
2471template <class _CharT, class _Traits, class _Allocator>
2472template<class _InputIterator>
2473__enable_if_t
2474<
2475     __is_exactly_cpp17_input_iterator<_InputIterator>::value,
2476    basic_string<_CharT, _Traits, _Allocator>&
2477>
2478basic_string<_CharT, _Traits, _Allocator>::assign(_InputIterator __first, _InputIterator __last)
2479{
2480    const basic_string __temp(__first, __last, __alloc());
2481    assign(__temp.data(), __temp.size());
2482    return *this;
2483}
2484
2485template <class _CharT, class _Traits, class _Allocator>
2486template<class _ForwardIterator>
2487__enable_if_t
2488<
2489    __is_cpp17_forward_iterator<_ForwardIterator>::value,
2490    basic_string<_CharT, _Traits, _Allocator>&
2491>
2492basic_string<_CharT, _Traits, _Allocator>::assign(_ForwardIterator __first, _ForwardIterator __last)
2493{
2494    size_type __cap = capacity();
2495    size_type __n = __string_is_trivial_iterator<_ForwardIterator>::value ?
2496        static_cast<size_type>(_VSTD::distance(__first, __last)) : 0;
2497
2498    if (__string_is_trivial_iterator<_ForwardIterator>::value &&
2499        (__cap >= __n || !__addr_in_range(*__first)))
2500    {
2501        if (__cap < __n)
2502        {
2503            size_type __sz = size();
2504            __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2505        }
2506        pointer __p = __get_pointer();
2507        for (; __first != __last; ++__p, (void) ++__first)
2508            traits_type::assign(*__p, *__first);
2509        traits_type::assign(*__p, value_type());
2510        __set_size(__n);
2511        __invalidate_iterators_past(__n);
2512    }
2513    else
2514    {
2515        const basic_string __temp(__first, __last, __alloc());
2516        assign(__temp.data(), __temp.size());
2517    }
2518    return *this;
2519}
2520
2521template <class _CharT, class _Traits, class _Allocator>
2522basic_string<_CharT, _Traits, _Allocator>&
2523basic_string<_CharT, _Traits, _Allocator>::assign(const basic_string& __str, size_type __pos, size_type __n)
2524{
2525    size_type __sz = __str.size();
2526    if (__pos > __sz)
2527        this->__throw_out_of_range();
2528    return assign(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2529}
2530
2531template <class _CharT, class _Traits, class _Allocator>
2532template <class _Tp>
2533__enable_if_t
2534<
2535    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
2536    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2537    basic_string<_CharT, _Traits, _Allocator>&
2538>
2539basic_string<_CharT, _Traits, _Allocator>::assign(const _Tp & __t, size_type __pos, size_type __n)
2540{
2541    __self_view __sv = __t;
2542    size_type __sz = __sv.size();
2543    if (__pos > __sz)
2544        this->__throw_out_of_range();
2545    return assign(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2546}
2547
2548
2549template <class _CharT, class _Traits, class _Allocator>
2550basic_string<_CharT, _Traits, _Allocator>&
2551basic_string<_CharT, _Traits, _Allocator>::__assign_external(const value_type* __s) {
2552  return __assign_external(__s, traits_type::length(__s));
2553}
2554
2555template <class _CharT, class _Traits, class _Allocator>
2556basic_string<_CharT, _Traits, _Allocator>&
2557basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s)
2558{
2559    _LIBCPP_ASSERT(__s != nullptr, "string::assign received nullptr");
2560    return __builtin_constant_p(*__s)
2561               ? (__fits_in_sso(traits_type::length(__s))
2562                      ? __assign_short(__s, traits_type::length(__s))
2563                      : __assign_external(__s, traits_type::length(__s)))
2564               : __assign_external(__s);
2565}
2566// append
2567
2568template <class _CharT, class _Traits, class _Allocator>
2569basic_string<_CharT, _Traits, _Allocator>&
2570basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s, size_type __n)
2571{
2572    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::append received nullptr");
2573    size_type __cap = capacity();
2574    size_type __sz = size();
2575    if (__cap - __sz >= __n)
2576    {
2577        if (__n)
2578        {
2579            value_type* __p = _VSTD::__to_address(__get_pointer());
2580            traits_type::copy(__p + __sz, __s, __n);
2581            __sz += __n;
2582            __set_size(__sz);
2583            traits_type::assign(__p[__sz], value_type());
2584        }
2585    }
2586    else
2587        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __sz, 0, __n, __s);
2588    return *this;
2589}
2590
2591template <class _CharT, class _Traits, class _Allocator>
2592basic_string<_CharT, _Traits, _Allocator>&
2593basic_string<_CharT, _Traits, _Allocator>::append(size_type __n, value_type __c)
2594{
2595    if (__n)
2596    {
2597        size_type __cap = capacity();
2598        size_type __sz = size();
2599        if (__cap - __sz < __n)
2600            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2601        pointer __p = __get_pointer();
2602        traits_type::assign(_VSTD::__to_address(__p) + __sz, __n, __c);
2603        __sz += __n;
2604        __set_size(__sz);
2605        traits_type::assign(__p[__sz], value_type());
2606    }
2607    return *this;
2608}
2609
2610template <class _CharT, class _Traits, class _Allocator>
2611inline void
2612basic_string<_CharT, _Traits, _Allocator>::__append_default_init(size_type __n)
2613{
2614    if (__n)
2615    {
2616        size_type __cap = capacity();
2617        size_type __sz = size();
2618        if (__cap - __sz < __n)
2619            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2620        pointer __p = __get_pointer();
2621        __sz += __n;
2622        __set_size(__sz);
2623        traits_type::assign(__p[__sz], value_type());
2624    }
2625}
2626
2627template <class _CharT, class _Traits, class _Allocator>
2628void
2629basic_string<_CharT, _Traits, _Allocator>::push_back(value_type __c)
2630{
2631    bool __is_short = !__is_long();
2632    size_type __cap;
2633    size_type __sz;
2634    if (__is_short)
2635    {
2636        __cap = __min_cap - 1;
2637        __sz = __get_short_size();
2638    }
2639    else
2640    {
2641        __cap = __get_long_cap() - 1;
2642        __sz = __get_long_size();
2643    }
2644    if (__sz == __cap)
2645    {
2646        __grow_by(__cap, 1, __sz, __sz, 0);
2647        __is_short = false; // the string is always long after __grow_by
2648    }
2649    pointer __p;
2650    if (__is_short)
2651    {
2652        __p = __get_short_pointer() + __sz;
2653        __set_short_size(__sz+1);
2654    }
2655    else
2656    {
2657        __p = __get_long_pointer() + __sz;
2658        __set_long_size(__sz+1);
2659    }
2660    traits_type::assign(*__p, __c);
2661    traits_type::assign(*++__p, value_type());
2662}
2663
2664template <class _CharT, class _Traits, class _Allocator>
2665template<class _ForwardIterator>
2666__enable_if_t
2667<
2668    __is_cpp17_forward_iterator<_ForwardIterator>::value,
2669    basic_string<_CharT, _Traits, _Allocator>&
2670>
2671basic_string<_CharT, _Traits, _Allocator>::append(
2672    _ForwardIterator __first, _ForwardIterator __last)
2673{
2674    size_type __sz = size();
2675    size_type __cap = capacity();
2676    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2677    if (__n)
2678    {
2679        if (__string_is_trivial_iterator<_ForwardIterator>::value &&
2680            !__addr_in_range(*__first))
2681        {
2682            if (__cap - __sz < __n)
2683                __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2684            pointer __p = __get_pointer() + __sz;
2685            for (; __first != __last; ++__p, (void) ++__first)
2686                traits_type::assign(*__p, *__first);
2687            traits_type::assign(*__p, value_type());
2688            __set_size(__sz + __n);
2689        }
2690        else
2691        {
2692            const basic_string __temp(__first, __last, __alloc());
2693            append(__temp.data(), __temp.size());
2694        }
2695    }
2696    return *this;
2697}
2698
2699template <class _CharT, class _Traits, class _Allocator>
2700inline
2701basic_string<_CharT, _Traits, _Allocator>&
2702basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str)
2703{
2704    return append(__str.data(), __str.size());
2705}
2706
2707template <class _CharT, class _Traits, class _Allocator>
2708basic_string<_CharT, _Traits, _Allocator>&
2709basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str, size_type __pos, size_type __n)
2710{
2711    size_type __sz = __str.size();
2712    if (__pos > __sz)
2713        this->__throw_out_of_range();
2714    return append(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2715}
2716
2717template <class _CharT, class _Traits, class _Allocator>
2718template <class _Tp>
2719    __enable_if_t
2720    <
2721        __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2722        basic_string<_CharT, _Traits, _Allocator>&
2723    >
2724basic_string<_CharT, _Traits, _Allocator>::append(const _Tp & __t, size_type __pos, size_type __n)
2725{
2726    __self_view __sv = __t;
2727    size_type __sz = __sv.size();
2728    if (__pos > __sz)
2729        this->__throw_out_of_range();
2730    return append(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2731}
2732
2733template <class _CharT, class _Traits, class _Allocator>
2734basic_string<_CharT, _Traits, _Allocator>&
2735basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s)
2736{
2737    _LIBCPP_ASSERT(__s != nullptr, "string::append received nullptr");
2738    return append(__s, traits_type::length(__s));
2739}
2740
2741// insert
2742
2743template <class _CharT, class _Traits, class _Allocator>
2744basic_string<_CharT, _Traits, _Allocator>&
2745basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s, size_type __n)
2746{
2747    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::insert received nullptr");
2748    size_type __sz = size();
2749    if (__pos > __sz)
2750        this->__throw_out_of_range();
2751    size_type __cap = capacity();
2752    if (__cap - __sz >= __n)
2753    {
2754        if (__n)
2755        {
2756            value_type* __p = _VSTD::__to_address(__get_pointer());
2757            size_type __n_move = __sz - __pos;
2758            if (__n_move != 0)
2759            {
2760                if (__p + __pos <= __s && __s < __p + __sz)
2761                    __s += __n;
2762                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2763            }
2764            traits_type::move(__p + __pos, __s, __n);
2765            __sz += __n;
2766            __set_size(__sz);
2767            traits_type::assign(__p[__sz], value_type());
2768        }
2769    }
2770    else
2771        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __pos, 0, __n, __s);
2772    return *this;
2773}
2774
2775template <class _CharT, class _Traits, class _Allocator>
2776basic_string<_CharT, _Traits, _Allocator>&
2777basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, size_type __n, value_type __c)
2778{
2779    size_type __sz = size();
2780    if (__pos > __sz)
2781        this->__throw_out_of_range();
2782    if (__n)
2783    {
2784        size_type __cap = capacity();
2785        value_type* __p;
2786        if (__cap - __sz >= __n)
2787        {
2788            __p = _VSTD::__to_address(__get_pointer());
2789            size_type __n_move = __sz - __pos;
2790            if (__n_move != 0)
2791                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2792        }
2793        else
2794        {
2795            __grow_by(__cap, __sz + __n - __cap, __sz, __pos, 0, __n);
2796            __p = _VSTD::__to_address(__get_long_pointer());
2797        }
2798        traits_type::assign(__p + __pos, __n, __c);
2799        __sz += __n;
2800        __set_size(__sz);
2801        traits_type::assign(__p[__sz], value_type());
2802    }
2803    return *this;
2804}
2805
2806template <class _CharT, class _Traits, class _Allocator>
2807template<class _InputIterator>
2808__enable_if_t
2809<
2810   __is_exactly_cpp17_input_iterator<_InputIterator>::value,
2811   typename basic_string<_CharT, _Traits, _Allocator>::iterator
2812>
2813basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _InputIterator __first, _InputIterator __last)
2814{
2815  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2816                       "string::insert(iterator, range) called with an iterator not"
2817                       " referring to this string");
2818  const basic_string __temp(__first, __last, __alloc());
2819  return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2820}
2821
2822template <class _CharT, class _Traits, class _Allocator>
2823template<class _ForwardIterator>
2824__enable_if_t
2825<
2826    __is_cpp17_forward_iterator<_ForwardIterator>::value,
2827    typename basic_string<_CharT, _Traits, _Allocator>::iterator
2828>
2829basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last)
2830{
2831  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2832                       "string::insert(iterator, range) called with an iterator not"
2833                       " referring to this string");
2834
2835    size_type __ip = static_cast<size_type>(__pos - begin());
2836    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2837    if (__n)
2838    {
2839        if (__string_is_trivial_iterator<_ForwardIterator>::value &&
2840            !__addr_in_range(*__first))
2841        {
2842            size_type __sz = size();
2843            size_type __cap = capacity();
2844            value_type* __p;
2845            if (__cap - __sz >= __n)
2846            {
2847                __p = _VSTD::__to_address(__get_pointer());
2848                size_type __n_move = __sz - __ip;
2849                if (__n_move != 0)
2850                    traits_type::move(__p + __ip + __n, __p + __ip, __n_move);
2851            }
2852            else
2853            {
2854                __grow_by(__cap, __sz + __n - __cap, __sz, __ip, 0, __n);
2855                __p = _VSTD::__to_address(__get_long_pointer());
2856            }
2857            __sz += __n;
2858            __set_size(__sz);
2859            traits_type::assign(__p[__sz], value_type());
2860            for (__p += __ip; __first != __last; ++__p, (void) ++__first)
2861                traits_type::assign(*__p, *__first);
2862        }
2863        else
2864        {
2865            const basic_string __temp(__first, __last, __alloc());
2866            return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2867        }
2868    }
2869    return begin() + __ip;
2870}
2871
2872template <class _CharT, class _Traits, class _Allocator>
2873inline
2874basic_string<_CharT, _Traits, _Allocator>&
2875basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str)
2876{
2877    return insert(__pos1, __str.data(), __str.size());
2878}
2879
2880template <class _CharT, class _Traits, class _Allocator>
2881basic_string<_CharT, _Traits, _Allocator>&
2882basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str,
2883                                                  size_type __pos2, size_type __n)
2884{
2885    size_type __str_sz = __str.size();
2886    if (__pos2 > __str_sz)
2887        this->__throw_out_of_range();
2888    return insert(__pos1, __str.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2889}
2890
2891template <class _CharT, class _Traits, class _Allocator>
2892template <class _Tp>
2893__enable_if_t
2894<
2895    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2896    basic_string<_CharT, _Traits, _Allocator>&
2897>
2898basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const _Tp& __t,
2899                                                  size_type __pos2, size_type __n)
2900{
2901    __self_view __sv = __t;
2902    size_type __str_sz = __sv.size();
2903    if (__pos2 > __str_sz)
2904        this->__throw_out_of_range();
2905    return insert(__pos1, __sv.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2906}
2907
2908template <class _CharT, class _Traits, class _Allocator>
2909basic_string<_CharT, _Traits, _Allocator>&
2910basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s)
2911{
2912    _LIBCPP_ASSERT(__s != nullptr, "string::insert received nullptr");
2913    return insert(__pos, __s, traits_type::length(__s));
2914}
2915
2916template <class _CharT, class _Traits, class _Allocator>
2917typename basic_string<_CharT, _Traits, _Allocator>::iterator
2918basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, value_type __c)
2919{
2920    size_type __ip = static_cast<size_type>(__pos - begin());
2921    size_type __sz = size();
2922    size_type __cap = capacity();
2923    value_type* __p;
2924    if (__cap == __sz)
2925    {
2926        __grow_by(__cap, 1, __sz, __ip, 0, 1);
2927        __p = _VSTD::__to_address(__get_long_pointer());
2928    }
2929    else
2930    {
2931        __p = _VSTD::__to_address(__get_pointer());
2932        size_type __n_move = __sz - __ip;
2933        if (__n_move != 0)
2934            traits_type::move(__p + __ip + 1, __p + __ip, __n_move);
2935    }
2936    traits_type::assign(__p[__ip], __c);
2937    traits_type::assign(__p[++__sz], value_type());
2938    __set_size(__sz);
2939    return begin() + static_cast<difference_type>(__ip);
2940}
2941
2942template <class _CharT, class _Traits, class _Allocator>
2943inline
2944typename basic_string<_CharT, _Traits, _Allocator>::iterator
2945basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, size_type __n, value_type __c)
2946{
2947  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2948                       "string::insert(iterator, n, value) called with an iterator not"
2949                       " referring to this string");
2950  difference_type __p = __pos - begin();
2951  insert(static_cast<size_type>(__p), __n, __c);
2952  return begin() + __p;
2953}
2954
2955// replace
2956
2957template <class _CharT, class _Traits, class _Allocator>
2958basic_string<_CharT, _Traits, _Allocator>&
2959basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2)
2960    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
2961{
2962    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::replace received nullptr");
2963    size_type __sz = size();
2964    if (__pos > __sz)
2965        this->__throw_out_of_range();
2966    __n1 = _VSTD::min(__n1, __sz - __pos);
2967    size_type __cap = capacity();
2968    if (__cap - __sz + __n1 >= __n2)
2969    {
2970        value_type* __p = _VSTD::__to_address(__get_pointer());
2971        if (__n1 != __n2)
2972        {
2973            size_type __n_move = __sz - __pos - __n1;
2974            if (__n_move != 0)
2975            {
2976                if (__n1 > __n2)
2977                {
2978                    traits_type::move(__p + __pos, __s, __n2);
2979                    traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
2980                    return __null_terminate_at(__p, __sz + (__n2 - __n1));
2981                }
2982                if (__p + __pos < __s && __s < __p + __sz)
2983                {
2984                    if (__p + __pos + __n1 <= __s)
2985                        __s += __n2 - __n1;
2986                    else // __p + __pos < __s < __p + __pos + __n1
2987                    {
2988                        traits_type::move(__p + __pos, __s, __n1);
2989                        __pos += __n1;
2990                        __s += __n2;
2991                        __n2 -= __n1;
2992                        __n1 = 0;
2993                    }
2994                }
2995                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
2996            }
2997        }
2998        traits_type::move(__p + __pos, __s, __n2);
2999        return __null_terminate_at(__p, __sz + (__n2 - __n1));
3000    }
3001    else
3002        __grow_by_and_replace(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2, __s);
3003    return *this;
3004}
3005
3006template <class _CharT, class _Traits, class _Allocator>
3007basic_string<_CharT, _Traits, _Allocator>&
3008basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, size_type __n2, value_type __c)
3009{
3010    size_type __sz = size();
3011    if (__pos > __sz)
3012        this->__throw_out_of_range();
3013    __n1 = _VSTD::min(__n1, __sz - __pos);
3014    size_type __cap = capacity();
3015    value_type* __p;
3016    if (__cap - __sz + __n1 >= __n2)
3017    {
3018        __p = _VSTD::__to_address(__get_pointer());
3019        if (__n1 != __n2)
3020        {
3021            size_type __n_move = __sz - __pos - __n1;
3022            if (__n_move != 0)
3023                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
3024        }
3025    }
3026    else
3027    {
3028        __grow_by(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2);
3029        __p = _VSTD::__to_address(__get_long_pointer());
3030    }
3031    traits_type::assign(__p + __pos, __n2, __c);
3032    return __null_terminate_at(__p, __sz - (__n1 - __n2));
3033}
3034
3035template <class _CharT, class _Traits, class _Allocator>
3036template<class _InputIterator>
3037__enable_if_t
3038<
3039    __is_cpp17_input_iterator<_InputIterator>::value,
3040    basic_string<_CharT, _Traits, _Allocator>&
3041>
3042basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2,
3043                                                   _InputIterator __j1, _InputIterator __j2)
3044{
3045    const basic_string __temp(__j1, __j2, __alloc());
3046    return this->replace(__i1, __i2, __temp);
3047}
3048
3049template <class _CharT, class _Traits, class _Allocator>
3050inline
3051basic_string<_CharT, _Traits, _Allocator>&
3052basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str)
3053{
3054    return replace(__pos1, __n1, __str.data(), __str.size());
3055}
3056
3057template <class _CharT, class _Traits, class _Allocator>
3058basic_string<_CharT, _Traits, _Allocator>&
3059basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str,
3060                                                   size_type __pos2, size_type __n2)
3061{
3062    size_type __str_sz = __str.size();
3063    if (__pos2 > __str_sz)
3064        this->__throw_out_of_range();
3065    return replace(__pos1, __n1, __str.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
3066}
3067
3068template <class _CharT, class _Traits, class _Allocator>
3069template <class _Tp>
3070__enable_if_t
3071<
3072    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
3073    basic_string<_CharT, _Traits, _Allocator>&
3074>
3075basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const _Tp& __t,
3076                                                   size_type __pos2, size_type __n2)
3077{
3078    __self_view __sv = __t;
3079    size_type __str_sz = __sv.size();
3080    if (__pos2 > __str_sz)
3081        this->__throw_out_of_range();
3082    return replace(__pos1, __n1, __sv.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
3083}
3084
3085template <class _CharT, class _Traits, class _Allocator>
3086basic_string<_CharT, _Traits, _Allocator>&
3087basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s)
3088{
3089    _LIBCPP_ASSERT(__s != nullptr, "string::replace received nullptr");
3090    return replace(__pos, __n1, __s, traits_type::length(__s));
3091}
3092
3093template <class _CharT, class _Traits, class _Allocator>
3094inline
3095basic_string<_CharT, _Traits, _Allocator>&
3096basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const basic_string& __str)
3097{
3098    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1),
3099                   __str.data(), __str.size());
3100}
3101
3102template <class _CharT, class _Traits, class _Allocator>
3103inline
3104basic_string<_CharT, _Traits, _Allocator>&
3105basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n)
3106{
3107    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s, __n);
3108}
3109
3110template <class _CharT, class _Traits, class _Allocator>
3111inline
3112basic_string<_CharT, _Traits, _Allocator>&
3113basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s)
3114{
3115    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s);
3116}
3117
3118template <class _CharT, class _Traits, class _Allocator>
3119inline
3120basic_string<_CharT, _Traits, _Allocator>&
3121basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c)
3122{
3123    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __n, __c);
3124}
3125
3126// erase
3127
3128// 'externally instantiated' erase() implementation, called when __n != npos.
3129// Does not check __pos against size()
3130template <class _CharT, class _Traits, class _Allocator>
3131void
3132basic_string<_CharT, _Traits, _Allocator>::__erase_external_with_move(
3133    size_type __pos, size_type __n)
3134{
3135    if (__n)
3136    {
3137        size_type __sz = size();
3138        value_type* __p = _VSTD::__to_address(__get_pointer());
3139        __n = _VSTD::min(__n, __sz - __pos);
3140        size_type __n_move = __sz - __pos - __n;
3141        if (__n_move != 0)
3142            traits_type::move(__p + __pos, __p + __pos + __n, __n_move);
3143        __null_terminate_at(__p, __sz - __n);
3144    }
3145}
3146
3147template <class _CharT, class _Traits, class _Allocator>
3148basic_string<_CharT, _Traits, _Allocator>&
3149basic_string<_CharT, _Traits, _Allocator>::erase(size_type __pos,
3150                                                 size_type __n) {
3151  if (__pos > size()) this->__throw_out_of_range();
3152  if (__n == npos) {
3153    __erase_to_end(__pos);
3154  } else {
3155    __erase_external_with_move(__pos, __n);
3156  }
3157  return *this;
3158}
3159
3160template <class _CharT, class _Traits, class _Allocator>
3161inline
3162typename basic_string<_CharT, _Traits, _Allocator>::iterator
3163basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __pos)
3164{
3165  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
3166                       "string::erase(iterator) called with an iterator not"
3167                       " referring to this string");
3168
3169  _LIBCPP_ASSERT(__pos != end(), "string::erase(iterator) called with a non-dereferenceable iterator");
3170  iterator __b = begin();
3171  size_type __r = static_cast<size_type>(__pos - __b);
3172  erase(__r, 1);
3173  return __b + static_cast<difference_type>(__r);
3174}
3175
3176template <class _CharT, class _Traits, class _Allocator>
3177inline
3178typename basic_string<_CharT, _Traits, _Allocator>::iterator
3179basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __first, const_iterator __last)
3180{
3181  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__first) == this,
3182                       "string::erase(iterator,  iterator) called with an iterator not"
3183                       " referring to this string");
3184
3185  _LIBCPP_ASSERT(__first <= __last, "string::erase(first, last) called with invalid range");
3186  iterator __b = begin();
3187  size_type __r = static_cast<size_type>(__first - __b);
3188  erase(__r, static_cast<size_type>(__last - __first));
3189  return __b + static_cast<difference_type>(__r);
3190}
3191
3192template <class _CharT, class _Traits, class _Allocator>
3193inline
3194void
3195basic_string<_CharT, _Traits, _Allocator>::pop_back()
3196{
3197    _LIBCPP_ASSERT(!empty(), "string::pop_back(): string is already empty");
3198    __erase_to_end(size() - 1);
3199}
3200
3201template <class _CharT, class _Traits, class _Allocator>
3202inline
3203void
3204basic_string<_CharT, _Traits, _Allocator>::clear() _NOEXCEPT
3205{
3206    __invalidate_all_iterators();
3207    if (__is_long())
3208    {
3209        traits_type::assign(*__get_long_pointer(), value_type());
3210        __set_long_size(0);
3211    }
3212    else
3213    {
3214        traits_type::assign(*__get_short_pointer(), value_type());
3215        __set_short_size(0);
3216    }
3217}
3218
3219template <class _CharT, class _Traits, class _Allocator>
3220inline
3221void
3222basic_string<_CharT, _Traits, _Allocator>::__erase_to_end(size_type __pos)
3223{
3224  __null_terminate_at(_VSTD::__to_address(__get_pointer()), __pos);
3225}
3226
3227template <class _CharT, class _Traits, class _Allocator>
3228void
3229basic_string<_CharT, _Traits, _Allocator>::resize(size_type __n, value_type __c)
3230{
3231    size_type __sz = size();
3232    if (__n > __sz)
3233        append(__n - __sz, __c);
3234    else
3235        __erase_to_end(__n);
3236}
3237
3238template <class _CharT, class _Traits, class _Allocator>
3239inline void
3240basic_string<_CharT, _Traits, _Allocator>::__resize_default_init(size_type __n)
3241{
3242    size_type __sz = size();
3243    if (__n > __sz) {
3244       __append_default_init(__n - __sz);
3245    } else
3246        __erase_to_end(__n);
3247}
3248
3249template <class _CharT, class _Traits, class _Allocator>
3250inline
3251typename basic_string<_CharT, _Traits, _Allocator>::size_type
3252basic_string<_CharT, _Traits, _Allocator>::max_size() const _NOEXCEPT
3253{
3254    size_type __m = __alloc_traits::max_size(__alloc());
3255#ifdef _LIBCPP_BIG_ENDIAN
3256    return (__m <= ~__long_mask ? __m : __m/2) - __alignment;
3257#else
3258    return __m - __alignment;
3259#endif
3260}
3261
3262template <class _CharT, class _Traits, class _Allocator>
3263void
3264basic_string<_CharT, _Traits, _Allocator>::reserve(size_type __requested_capacity)
3265{
3266    if (__requested_capacity > max_size())
3267        this->__throw_length_error();
3268
3269#if _LIBCPP_STD_VER > 17
3270    // Reserve never shrinks as of C++20.
3271    if (__requested_capacity <= capacity()) return;
3272#endif
3273
3274    size_type __target_capacity = _VSTD::max(__requested_capacity, size());
3275    __target_capacity = __recommend(__target_capacity);
3276    if (__target_capacity == capacity()) return;
3277
3278    __shrink_or_extend(__target_capacity);
3279}
3280
3281template <class _CharT, class _Traits, class _Allocator>
3282inline
3283void
3284basic_string<_CharT, _Traits, _Allocator>::shrink_to_fit() _NOEXCEPT
3285{
3286    size_type __target_capacity = __recommend(size());
3287    if (__target_capacity == capacity()) return;
3288
3289    __shrink_or_extend(__target_capacity);
3290}
3291
3292template <class _CharT, class _Traits, class _Allocator>
3293inline
3294void
3295basic_string<_CharT, _Traits, _Allocator>::__shrink_or_extend(size_type __target_capacity)
3296{
3297    size_type __cap = capacity();
3298    size_type __sz = size();
3299
3300    pointer __new_data, __p;
3301    bool __was_long, __now_long;
3302    if (__target_capacity == __min_cap - 1)
3303    {
3304        __was_long = true;
3305        __now_long = false;
3306        __new_data = __get_short_pointer();
3307        __p = __get_long_pointer();
3308    }
3309    else
3310    {
3311        if (__target_capacity > __cap)
3312            __new_data = __alloc_traits::allocate(__alloc(), __target_capacity+1);
3313        else
3314        {
3315        #ifndef _LIBCPP_NO_EXCEPTIONS
3316            try
3317            {
3318        #endif // _LIBCPP_NO_EXCEPTIONS
3319                __new_data = __alloc_traits::allocate(__alloc(), __target_capacity+1);
3320        #ifndef _LIBCPP_NO_EXCEPTIONS
3321            }
3322            catch (...)
3323            {
3324                return;
3325            }
3326        #else  // _LIBCPP_NO_EXCEPTIONS
3327            if (__new_data == nullptr)
3328                return;
3329        #endif // _LIBCPP_NO_EXCEPTIONS
3330        }
3331        __now_long = true;
3332        __was_long = __is_long();
3333        __p = __get_pointer();
3334    }
3335    traits_type::copy(_VSTD::__to_address(__new_data),
3336                        _VSTD::__to_address(__p), size()+1);
3337    if (__was_long)
3338        __alloc_traits::deallocate(__alloc(), __p, __cap+1);
3339    if (__now_long)
3340    {
3341        __set_long_cap(__target_capacity+1);
3342        __set_long_size(__sz);
3343        __set_long_pointer(__new_data);
3344    }
3345    else
3346        __set_short_size(__sz);
3347    __invalidate_all_iterators();
3348}
3349
3350template <class _CharT, class _Traits, class _Allocator>
3351inline
3352typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3353basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) const _NOEXCEPT
3354{
3355    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3356    return *(data() + __pos);
3357}
3358
3359template <class _CharT, class _Traits, class _Allocator>
3360inline
3361typename basic_string<_CharT, _Traits, _Allocator>::reference
3362basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) _NOEXCEPT
3363{
3364    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3365    return *(__get_pointer() + __pos);
3366}
3367
3368template <class _CharT, class _Traits, class _Allocator>
3369typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3370basic_string<_CharT, _Traits, _Allocator>::at(size_type __n) const
3371{
3372    if (__n >= size())
3373        this->__throw_out_of_range();
3374    return (*this)[__n];
3375}
3376
3377template <class _CharT, class _Traits, class _Allocator>
3378typename basic_string<_CharT, _Traits, _Allocator>::reference
3379basic_string<_CharT, _Traits, _Allocator>::at(size_type __n)
3380{
3381    if (__n >= size())
3382        this->__throw_out_of_range();
3383    return (*this)[__n];
3384}
3385
3386template <class _CharT, class _Traits, class _Allocator>
3387inline
3388typename basic_string<_CharT, _Traits, _Allocator>::reference
3389basic_string<_CharT, _Traits, _Allocator>::front() _NOEXCEPT
3390{
3391    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3392    return *__get_pointer();
3393}
3394
3395template <class _CharT, class _Traits, class _Allocator>
3396inline
3397typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3398basic_string<_CharT, _Traits, _Allocator>::front() const _NOEXCEPT
3399{
3400    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3401    return *data();
3402}
3403
3404template <class _CharT, class _Traits, class _Allocator>
3405inline
3406typename basic_string<_CharT, _Traits, _Allocator>::reference
3407basic_string<_CharT, _Traits, _Allocator>::back() _NOEXCEPT
3408{
3409    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3410    return *(__get_pointer() + size() - 1);
3411}
3412
3413template <class _CharT, class _Traits, class _Allocator>
3414inline
3415typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3416basic_string<_CharT, _Traits, _Allocator>::back() const _NOEXCEPT
3417{
3418    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3419    return *(data() + size() - 1);
3420}
3421
3422template <class _CharT, class _Traits, class _Allocator>
3423typename basic_string<_CharT, _Traits, _Allocator>::size_type
3424basic_string<_CharT, _Traits, _Allocator>::copy(value_type* __s, size_type __n, size_type __pos) const
3425{
3426    size_type __sz = size();
3427    if (__pos > __sz)
3428        this->__throw_out_of_range();
3429    size_type __rlen = _VSTD::min(__n, __sz - __pos);
3430    traits_type::copy(__s, data() + __pos, __rlen);
3431    return __rlen;
3432}
3433
3434template <class _CharT, class _Traits, class _Allocator>
3435inline
3436basic_string<_CharT, _Traits, _Allocator>
3437basic_string<_CharT, _Traits, _Allocator>::substr(size_type __pos, size_type __n) const
3438{
3439    return basic_string(*this, __pos, __n, __alloc());
3440}
3441
3442template <class _CharT, class _Traits, class _Allocator>
3443inline
3444void
3445basic_string<_CharT, _Traits, _Allocator>::swap(basic_string& __str)
3446#if _LIBCPP_STD_VER >= 14
3447        _NOEXCEPT
3448#else
3449        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
3450                    __is_nothrow_swappable<allocator_type>::value)
3451#endif
3452{
3453#if _LIBCPP_DEBUG_LEVEL == 2
3454    if (!__libcpp_is_constant_evaluated()) {
3455        if (!__is_long())
3456            __get_db()->__invalidate_all(this);
3457        if (!__str.__is_long())
3458            __get_db()->__invalidate_all(&__str);
3459        __get_db()->swap(this, &__str);
3460    }
3461#endif
3462    _LIBCPP_ASSERT(
3463        __alloc_traits::propagate_on_container_swap::value ||
3464        __alloc_traits::is_always_equal::value ||
3465        __alloc() == __str.__alloc(), "swapping non-equal allocators");
3466    _VSTD::swap(__r_.first(), __str.__r_.first());
3467    _VSTD::__swap_allocator(__alloc(), __str.__alloc());
3468}
3469
3470// find
3471
3472template <class _Traits>
3473struct _LIBCPP_HIDDEN __traits_eq
3474{
3475    typedef typename _Traits::char_type char_type;
3476    _LIBCPP_INLINE_VISIBILITY
3477    bool operator()(const char_type& __x, const char_type& __y) _NOEXCEPT
3478        {return _Traits::eq(__x, __y);}
3479};
3480
3481template<class _CharT, class _Traits, class _Allocator>
3482typename basic_string<_CharT, _Traits, _Allocator>::size_type
3483basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3484                                                size_type __pos,
3485                                                size_type __n) const _NOEXCEPT
3486{
3487    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find(): received nullptr");
3488    return __str_find<value_type, size_type, traits_type, npos>
3489        (data(), size(), __s, __pos, __n);
3490}
3491
3492template<class _CharT, class _Traits, class _Allocator>
3493inline
3494typename basic_string<_CharT, _Traits, _Allocator>::size_type
3495basic_string<_CharT, _Traits, _Allocator>::find(const basic_string& __str,
3496                                                size_type __pos) const _NOEXCEPT
3497{
3498    return __str_find<value_type, size_type, traits_type, npos>
3499        (data(), size(), __str.data(), __pos, __str.size());
3500}
3501
3502template<class _CharT, class _Traits, class _Allocator>
3503template <class _Tp>
3504__enable_if_t
3505<
3506    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3507    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3508>
3509basic_string<_CharT, _Traits, _Allocator>::find(const _Tp &__t,
3510                                                size_type __pos) const _NOEXCEPT
3511{
3512    __self_view __sv = __t;
3513    return __str_find<value_type, size_type, traits_type, npos>
3514        (data(), size(), __sv.data(), __pos, __sv.size());
3515}
3516
3517template<class _CharT, class _Traits, class _Allocator>
3518inline
3519typename basic_string<_CharT, _Traits, _Allocator>::size_type
3520basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3521                                                size_type __pos) const _NOEXCEPT
3522{
3523    _LIBCPP_ASSERT(__s != nullptr, "string::find(): received nullptr");
3524    return __str_find<value_type, size_type, traits_type, npos>
3525        (data(), size(), __s, __pos, traits_type::length(__s));
3526}
3527
3528template<class _CharT, class _Traits, class _Allocator>
3529typename basic_string<_CharT, _Traits, _Allocator>::size_type
3530basic_string<_CharT, _Traits, _Allocator>::find(value_type __c,
3531                                                size_type __pos) const _NOEXCEPT
3532{
3533    return __str_find<value_type, size_type, traits_type, npos>
3534        (data(), size(), __c, __pos);
3535}
3536
3537// rfind
3538
3539template<class _CharT, class _Traits, class _Allocator>
3540typename basic_string<_CharT, _Traits, _Allocator>::size_type
3541basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3542                                                 size_type __pos,
3543                                                 size_type __n) const _NOEXCEPT
3544{
3545    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::rfind(): received nullptr");
3546    return __str_rfind<value_type, size_type, traits_type, npos>
3547        (data(), size(), __s, __pos, __n);
3548}
3549
3550template<class _CharT, class _Traits, class _Allocator>
3551inline
3552typename basic_string<_CharT, _Traits, _Allocator>::size_type
3553basic_string<_CharT, _Traits, _Allocator>::rfind(const basic_string& __str,
3554                                                 size_type __pos) const _NOEXCEPT
3555{
3556    return __str_rfind<value_type, size_type, traits_type, npos>
3557        (data(), size(), __str.data(), __pos, __str.size());
3558}
3559
3560template<class _CharT, class _Traits, class _Allocator>
3561template <class _Tp>
3562__enable_if_t
3563<
3564    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3565    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3566>
3567basic_string<_CharT, _Traits, _Allocator>::rfind(const _Tp& __t,
3568                                                size_type __pos) const _NOEXCEPT
3569{
3570    __self_view __sv = __t;
3571    return __str_rfind<value_type, size_type, traits_type, npos>
3572        (data(), size(), __sv.data(), __pos, __sv.size());
3573}
3574
3575template<class _CharT, class _Traits, class _Allocator>
3576inline
3577typename basic_string<_CharT, _Traits, _Allocator>::size_type
3578basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3579                                                 size_type __pos) const _NOEXCEPT
3580{
3581    _LIBCPP_ASSERT(__s != nullptr, "string::rfind(): received nullptr");
3582    return __str_rfind<value_type, size_type, traits_type, npos>
3583        (data(), size(), __s, __pos, traits_type::length(__s));
3584}
3585
3586template<class _CharT, class _Traits, class _Allocator>
3587typename basic_string<_CharT, _Traits, _Allocator>::size_type
3588basic_string<_CharT, _Traits, _Allocator>::rfind(value_type __c,
3589                                                 size_type __pos) const _NOEXCEPT
3590{
3591    return __str_rfind<value_type, size_type, traits_type, npos>
3592        (data(), size(), __c, __pos);
3593}
3594
3595// find_first_of
3596
3597template<class _CharT, class _Traits, class _Allocator>
3598typename basic_string<_CharT, _Traits, _Allocator>::size_type
3599basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3600                                                         size_type __pos,
3601                                                         size_type __n) const _NOEXCEPT
3602{
3603    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_of(): received nullptr");
3604    return __str_find_first_of<value_type, size_type, traits_type, npos>
3605        (data(), size(), __s, __pos, __n);
3606}
3607
3608template<class _CharT, class _Traits, class _Allocator>
3609inline
3610typename basic_string<_CharT, _Traits, _Allocator>::size_type
3611basic_string<_CharT, _Traits, _Allocator>::find_first_of(const basic_string& __str,
3612                                                         size_type __pos) const _NOEXCEPT
3613{
3614    return __str_find_first_of<value_type, size_type, traits_type, npos>
3615        (data(), size(), __str.data(), __pos, __str.size());
3616}
3617
3618template<class _CharT, class _Traits, class _Allocator>
3619template <class _Tp>
3620__enable_if_t
3621<
3622    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3623    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3624>
3625basic_string<_CharT, _Traits, _Allocator>::find_first_of(const _Tp& __t,
3626                                                size_type __pos) const _NOEXCEPT
3627{
3628    __self_view __sv = __t;
3629    return __str_find_first_of<value_type, size_type, traits_type, npos>
3630        (data(), size(), __sv.data(), __pos, __sv.size());
3631}
3632
3633template<class _CharT, class _Traits, class _Allocator>
3634inline
3635typename basic_string<_CharT, _Traits, _Allocator>::size_type
3636basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3637                                                         size_type __pos) const _NOEXCEPT
3638{
3639    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_of(): received nullptr");
3640    return __str_find_first_of<value_type, size_type, traits_type, npos>
3641        (data(), size(), __s, __pos, traits_type::length(__s));
3642}
3643
3644template<class _CharT, class _Traits, class _Allocator>
3645inline
3646typename basic_string<_CharT, _Traits, _Allocator>::size_type
3647basic_string<_CharT, _Traits, _Allocator>::find_first_of(value_type __c,
3648                                                         size_type __pos) const _NOEXCEPT
3649{
3650    return find(__c, __pos);
3651}
3652
3653// find_last_of
3654
3655template<class _CharT, class _Traits, class _Allocator>
3656typename basic_string<_CharT, _Traits, _Allocator>::size_type
3657basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3658                                                        size_type __pos,
3659                                                        size_type __n) const _NOEXCEPT
3660{
3661    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_of(): received nullptr");
3662    return __str_find_last_of<value_type, size_type, traits_type, npos>
3663        (data(), size(), __s, __pos, __n);
3664}
3665
3666template<class _CharT, class _Traits, class _Allocator>
3667inline
3668typename basic_string<_CharT, _Traits, _Allocator>::size_type
3669basic_string<_CharT, _Traits, _Allocator>::find_last_of(const basic_string& __str,
3670                                                        size_type __pos) const _NOEXCEPT
3671{
3672    return __str_find_last_of<value_type, size_type, traits_type, npos>
3673        (data(), size(), __str.data(), __pos, __str.size());
3674}
3675
3676template<class _CharT, class _Traits, class _Allocator>
3677template <class _Tp>
3678__enable_if_t
3679<
3680    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3681    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3682>
3683basic_string<_CharT, _Traits, _Allocator>::find_last_of(const _Tp& __t,
3684                                                size_type __pos) const _NOEXCEPT
3685{
3686    __self_view __sv = __t;
3687    return __str_find_last_of<value_type, size_type, traits_type, npos>
3688        (data(), size(), __sv.data(), __pos, __sv.size());
3689}
3690
3691template<class _CharT, class _Traits, class _Allocator>
3692inline
3693typename basic_string<_CharT, _Traits, _Allocator>::size_type
3694basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3695                                                        size_type __pos) const _NOEXCEPT
3696{
3697    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_of(): received nullptr");
3698    return __str_find_last_of<value_type, size_type, traits_type, npos>
3699        (data(), size(), __s, __pos, traits_type::length(__s));
3700}
3701
3702template<class _CharT, class _Traits, class _Allocator>
3703inline
3704typename basic_string<_CharT, _Traits, _Allocator>::size_type
3705basic_string<_CharT, _Traits, _Allocator>::find_last_of(value_type __c,
3706                                                        size_type __pos) const _NOEXCEPT
3707{
3708    return rfind(__c, __pos);
3709}
3710
3711// find_first_not_of
3712
3713template<class _CharT, class _Traits, class _Allocator>
3714typename basic_string<_CharT, _Traits, _Allocator>::size_type
3715basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3716                                                             size_type __pos,
3717                                                             size_type __n) const _NOEXCEPT
3718{
3719    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_not_of(): received nullptr");
3720    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3721        (data(), size(), __s, __pos, __n);
3722}
3723
3724template<class _CharT, class _Traits, class _Allocator>
3725inline
3726typename basic_string<_CharT, _Traits, _Allocator>::size_type
3727basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const basic_string& __str,
3728                                                             size_type __pos) const _NOEXCEPT
3729{
3730    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3731        (data(), size(), __str.data(), __pos, __str.size());
3732}
3733
3734template<class _CharT, class _Traits, class _Allocator>
3735template <class _Tp>
3736__enable_if_t
3737<
3738    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3739    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3740>
3741basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const _Tp& __t,
3742                                                size_type __pos) const _NOEXCEPT
3743{
3744    __self_view __sv = __t;
3745    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3746        (data(), size(), __sv.data(), __pos, __sv.size());
3747}
3748
3749template<class _CharT, class _Traits, class _Allocator>
3750inline
3751typename basic_string<_CharT, _Traits, _Allocator>::size_type
3752basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3753                                                             size_type __pos) const _NOEXCEPT
3754{
3755    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_not_of(): received nullptr");
3756    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3757        (data(), size(), __s, __pos, traits_type::length(__s));
3758}
3759
3760template<class _CharT, class _Traits, class _Allocator>
3761inline
3762typename basic_string<_CharT, _Traits, _Allocator>::size_type
3763basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(value_type __c,
3764                                                             size_type __pos) const _NOEXCEPT
3765{
3766    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3767        (data(), size(), __c, __pos);
3768}
3769
3770// find_last_not_of
3771
3772template<class _CharT, class _Traits, class _Allocator>
3773typename basic_string<_CharT, _Traits, _Allocator>::size_type
3774basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3775                                                            size_type __pos,
3776                                                            size_type __n) const _NOEXCEPT
3777{
3778    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_not_of(): received nullptr");
3779    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3780        (data(), size(), __s, __pos, __n);
3781}
3782
3783template<class _CharT, class _Traits, class _Allocator>
3784inline
3785typename basic_string<_CharT, _Traits, _Allocator>::size_type
3786basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const basic_string& __str,
3787                                                            size_type __pos) const _NOEXCEPT
3788{
3789    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3790        (data(), size(), __str.data(), __pos, __str.size());
3791}
3792
3793template<class _CharT, class _Traits, class _Allocator>
3794template <class _Tp>
3795__enable_if_t
3796<
3797    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3798    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3799>
3800basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const _Tp& __t,
3801                                                size_type __pos) const _NOEXCEPT
3802{
3803    __self_view __sv = __t;
3804    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3805        (data(), size(), __sv.data(), __pos, __sv.size());
3806}
3807
3808template<class _CharT, class _Traits, class _Allocator>
3809inline
3810typename basic_string<_CharT, _Traits, _Allocator>::size_type
3811basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3812                                                            size_type __pos) const _NOEXCEPT
3813{
3814    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_not_of(): received nullptr");
3815    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3816        (data(), size(), __s, __pos, traits_type::length(__s));
3817}
3818
3819template<class _CharT, class _Traits, class _Allocator>
3820inline
3821typename basic_string<_CharT, _Traits, _Allocator>::size_type
3822basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(value_type __c,
3823                                                            size_type __pos) const _NOEXCEPT
3824{
3825    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3826        (data(), size(), __c, __pos);
3827}
3828
3829// compare
3830
3831template <class _CharT, class _Traits, class _Allocator>
3832template <class _Tp>
3833__enable_if_t
3834<
3835    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3836    int
3837>
3838basic_string<_CharT, _Traits, _Allocator>::compare(const _Tp& __t) const _NOEXCEPT
3839{
3840    __self_view __sv = __t;
3841    size_t __lhs_sz = size();
3842    size_t __rhs_sz = __sv.size();
3843    int __result = traits_type::compare(data(), __sv.data(),
3844                                        _VSTD::min(__lhs_sz, __rhs_sz));
3845    if (__result != 0)
3846        return __result;
3847    if (__lhs_sz < __rhs_sz)
3848        return -1;
3849    if (__lhs_sz > __rhs_sz)
3850        return 1;
3851    return 0;
3852}
3853
3854template <class _CharT, class _Traits, class _Allocator>
3855inline
3856int
3857basic_string<_CharT, _Traits, _Allocator>::compare(const basic_string& __str) const _NOEXCEPT
3858{
3859    return compare(__self_view(__str));
3860}
3861
3862template <class _CharT, class _Traits, class _Allocator>
3863int
3864basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3865                                                   size_type __n1,
3866                                                   const value_type* __s,
3867                                                   size_type __n2) const
3868{
3869    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::compare(): received nullptr");
3870    size_type __sz = size();
3871    if (__pos1 > __sz || __n2 == npos)
3872        this->__throw_out_of_range();
3873    size_type __rlen = _VSTD::min(__n1, __sz - __pos1);
3874    int __r = traits_type::compare(data() + __pos1, __s, _VSTD::min(__rlen, __n2));
3875    if (__r == 0)
3876    {
3877        if (__rlen < __n2)
3878            __r = -1;
3879        else if (__rlen > __n2)
3880            __r = 1;
3881    }
3882    return __r;
3883}
3884
3885template <class _CharT, class _Traits, class _Allocator>
3886template <class _Tp>
3887__enable_if_t
3888<
3889    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3890    int
3891>
3892basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3893                                                   size_type __n1,
3894                                                   const _Tp& __t) const
3895{
3896    __self_view __sv = __t;
3897    return compare(__pos1, __n1, __sv.data(), __sv.size());
3898}
3899
3900template <class _CharT, class _Traits, class _Allocator>
3901inline
3902int
3903basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3904                                                   size_type __n1,
3905                                                   const basic_string& __str) const
3906{
3907    return compare(__pos1, __n1, __str.data(), __str.size());
3908}
3909
3910template <class _CharT, class _Traits, class _Allocator>
3911template <class _Tp>
3912__enable_if_t
3913<
3914    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
3915    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
3916    int
3917>
3918basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3919                                                   size_type __n1,
3920                                                   const _Tp& __t,
3921                                                   size_type __pos2,
3922                                                   size_type __n2) const
3923{
3924    __self_view __sv = __t;
3925    return __self_view(*this).substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
3926}
3927
3928template <class _CharT, class _Traits, class _Allocator>
3929int
3930basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3931                                                   size_type __n1,
3932                                                   const basic_string& __str,
3933                                                   size_type __pos2,
3934                                                   size_type __n2) const
3935{
3936        return compare(__pos1, __n1, __self_view(__str), __pos2, __n2);
3937}
3938
3939template <class _CharT, class _Traits, class _Allocator>
3940int
3941basic_string<_CharT, _Traits, _Allocator>::compare(const value_type* __s) const _NOEXCEPT
3942{
3943    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3944    return compare(0, npos, __s, traits_type::length(__s));
3945}
3946
3947template <class _CharT, class _Traits, class _Allocator>
3948int
3949basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3950                                                   size_type __n1,
3951                                                   const value_type* __s) const
3952{
3953    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3954    return compare(__pos1, __n1, __s, traits_type::length(__s));
3955}
3956
3957// __invariants
3958
3959template<class _CharT, class _Traits, class _Allocator>
3960inline
3961bool
3962basic_string<_CharT, _Traits, _Allocator>::__invariants() const
3963{
3964    if (size() > capacity())
3965        return false;
3966    if (capacity() < __min_cap - 1)
3967        return false;
3968    if (data() == nullptr)
3969        return false;
3970    if (data()[size()] != value_type())
3971        return false;
3972    return true;
3973}
3974
3975// __clear_and_shrink
3976
3977template<class _CharT, class _Traits, class _Allocator>
3978inline
3979void
3980basic_string<_CharT, _Traits, _Allocator>::__clear_and_shrink() _NOEXCEPT
3981{
3982    clear();
3983    if(__is_long())
3984    {
3985        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), capacity() + 1);
3986        __set_long_cap(0);
3987        __set_short_size(0);
3988        traits_type::assign(*__get_short_pointer(), value_type());
3989    }
3990}
3991
3992// operator==
3993
3994template<class _CharT, class _Traits, class _Allocator>
3995inline _LIBCPP_INLINE_VISIBILITY
3996bool
3997operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
3998           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3999{
4000    size_t __lhs_sz = __lhs.size();
4001    return __lhs_sz == __rhs.size() && _Traits::compare(__lhs.data(),
4002                                                        __rhs.data(),
4003                                                        __lhs_sz) == 0;
4004}
4005
4006template<class _Allocator>
4007inline _LIBCPP_INLINE_VISIBILITY
4008bool
4009operator==(const basic_string<char, char_traits<char>, _Allocator>& __lhs,
4010           const basic_string<char, char_traits<char>, _Allocator>& __rhs) _NOEXCEPT
4011{
4012    size_t __lhs_sz = __lhs.size();
4013    if (__lhs_sz != __rhs.size())
4014        return false;
4015    const char* __lp = __lhs.data();
4016    const char* __rp = __rhs.data();
4017    if (__lhs.__is_long())
4018        return char_traits<char>::compare(__lp, __rp, __lhs_sz) == 0;
4019    for (; __lhs_sz != 0; --__lhs_sz, ++__lp, ++__rp)
4020        if (*__lp != *__rp)
4021            return false;
4022    return true;
4023}
4024
4025template<class _CharT, class _Traits, class _Allocator>
4026inline _LIBCPP_INLINE_VISIBILITY
4027bool
4028operator==(const _CharT* __lhs,
4029           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4030{
4031    typedef basic_string<_CharT, _Traits, _Allocator> _String;
4032    _LIBCPP_ASSERT(__lhs != nullptr, "operator==(char*, basic_string): received nullptr");
4033    size_t __lhs_len = _Traits::length(__lhs);
4034    if (__lhs_len != __rhs.size()) return false;
4035    return __rhs.compare(0, _String::npos, __lhs, __lhs_len) == 0;
4036}
4037
4038template<class _CharT, class _Traits, class _Allocator>
4039inline _LIBCPP_INLINE_VISIBILITY
4040bool
4041operator==(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
4042           const _CharT* __rhs) _NOEXCEPT
4043{
4044    typedef basic_string<_CharT, _Traits, _Allocator> _String;
4045    _LIBCPP_ASSERT(__rhs != nullptr, "operator==(basic_string, char*): received nullptr");
4046    size_t __rhs_len = _Traits::length(__rhs);
4047    if (__rhs_len != __lhs.size()) return false;
4048    return __lhs.compare(0, _String::npos, __rhs, __rhs_len) == 0;
4049}
4050
4051template<class _CharT, class _Traits, class _Allocator>
4052inline _LIBCPP_INLINE_VISIBILITY
4053bool
4054operator!=(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
4055           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4056{
4057    return !(__lhs == __rhs);
4058}
4059
4060template<class _CharT, class _Traits, class _Allocator>
4061inline _LIBCPP_INLINE_VISIBILITY
4062bool
4063operator!=(const _CharT* __lhs,
4064           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4065{
4066    return !(__lhs == __rhs);
4067}
4068
4069template<class _CharT, class _Traits, class _Allocator>
4070inline _LIBCPP_INLINE_VISIBILITY
4071bool
4072operator!=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4073           const _CharT* __rhs) _NOEXCEPT
4074{
4075    return !(__lhs == __rhs);
4076}
4077
4078// operator<
4079
4080template<class _CharT, class _Traits, class _Allocator>
4081inline _LIBCPP_INLINE_VISIBILITY
4082bool
4083operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4084           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4085{
4086    return __lhs.compare(__rhs) < 0;
4087}
4088
4089template<class _CharT, class _Traits, class _Allocator>
4090inline _LIBCPP_INLINE_VISIBILITY
4091bool
4092operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4093           const _CharT* __rhs) _NOEXCEPT
4094{
4095    return __lhs.compare(__rhs) < 0;
4096}
4097
4098template<class _CharT, class _Traits, class _Allocator>
4099inline _LIBCPP_INLINE_VISIBILITY
4100bool
4101operator< (const _CharT* __lhs,
4102           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4103{
4104    return __rhs.compare(__lhs) > 0;
4105}
4106
4107// operator>
4108
4109template<class _CharT, class _Traits, class _Allocator>
4110inline _LIBCPP_INLINE_VISIBILITY
4111bool
4112operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4113           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4114{
4115    return __rhs < __lhs;
4116}
4117
4118template<class _CharT, class _Traits, class _Allocator>
4119inline _LIBCPP_INLINE_VISIBILITY
4120bool
4121operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4122           const _CharT* __rhs) _NOEXCEPT
4123{
4124    return __rhs < __lhs;
4125}
4126
4127template<class _CharT, class _Traits, class _Allocator>
4128inline _LIBCPP_INLINE_VISIBILITY
4129bool
4130operator> (const _CharT* __lhs,
4131           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4132{
4133    return __rhs < __lhs;
4134}
4135
4136// operator<=
4137
4138template<class _CharT, class _Traits, class _Allocator>
4139inline _LIBCPP_INLINE_VISIBILITY
4140bool
4141operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4142           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4143{
4144    return !(__rhs < __lhs);
4145}
4146
4147template<class _CharT, class _Traits, class _Allocator>
4148inline _LIBCPP_INLINE_VISIBILITY
4149bool
4150operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4151           const _CharT* __rhs) _NOEXCEPT
4152{
4153    return !(__rhs < __lhs);
4154}
4155
4156template<class _CharT, class _Traits, class _Allocator>
4157inline _LIBCPP_INLINE_VISIBILITY
4158bool
4159operator<=(const _CharT* __lhs,
4160           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4161{
4162    return !(__rhs < __lhs);
4163}
4164
4165// operator>=
4166
4167template<class _CharT, class _Traits, class _Allocator>
4168inline _LIBCPP_INLINE_VISIBILITY
4169bool
4170operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4171           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4172{
4173    return !(__lhs < __rhs);
4174}
4175
4176template<class _CharT, class _Traits, class _Allocator>
4177inline _LIBCPP_INLINE_VISIBILITY
4178bool
4179operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4180           const _CharT* __rhs) _NOEXCEPT
4181{
4182    return !(__lhs < __rhs);
4183}
4184
4185template<class _CharT, class _Traits, class _Allocator>
4186inline _LIBCPP_INLINE_VISIBILITY
4187bool
4188operator>=(const _CharT* __lhs,
4189           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4190{
4191    return !(__lhs < __rhs);
4192}
4193
4194// operator +
4195
4196template<class _CharT, class _Traits, class _Allocator>
4197basic_string<_CharT, _Traits, _Allocator>
4198operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4199          const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4200{
4201    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4202    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4203    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4204    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4205    __r.append(__rhs.data(), __rhs_sz);
4206    return __r;
4207}
4208
4209template<class _CharT, class _Traits, class _Allocator>
4210basic_string<_CharT, _Traits, _Allocator>
4211operator+(const _CharT* __lhs , const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4212{
4213    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4214    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = _Traits::length(__lhs);
4215    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4216    __r.__init(__lhs, __lhs_sz, __lhs_sz + __rhs_sz);
4217    __r.append(__rhs.data(), __rhs_sz);
4218    return __r;
4219}
4220
4221template<class _CharT, class _Traits, class _Allocator>
4222basic_string<_CharT, _Traits, _Allocator>
4223operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4224{
4225    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4226    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4227    __r.__init(&__lhs, 1, 1 + __rhs_sz);
4228    __r.append(__rhs.data(), __rhs_sz);
4229    return __r;
4230}
4231
4232template<class _CharT, class _Traits, class _Allocator>
4233inline
4234basic_string<_CharT, _Traits, _Allocator>
4235operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs)
4236{
4237    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4238    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4239    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = _Traits::length(__rhs);
4240    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4241    __r.append(__rhs, __rhs_sz);
4242    return __r;
4243}
4244
4245template<class _CharT, class _Traits, class _Allocator>
4246basic_string<_CharT, _Traits, _Allocator>
4247operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, _CharT __rhs)
4248{
4249    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4250    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4251    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + 1);
4252    __r.push_back(__rhs);
4253    return __r;
4254}
4255
4256#ifndef _LIBCPP_CXX03_LANG
4257
4258template<class _CharT, class _Traits, class _Allocator>
4259inline _LIBCPP_INLINE_VISIBILITY
4260basic_string<_CharT, _Traits, _Allocator>
4261operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4262{
4263    return _VSTD::move(__lhs.append(__rhs));
4264}
4265
4266template<class _CharT, class _Traits, class _Allocator>
4267inline _LIBCPP_INLINE_VISIBILITY
4268basic_string<_CharT, _Traits, _Allocator>
4269operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4270{
4271    return _VSTD::move(__rhs.insert(0, __lhs));
4272}
4273
4274template<class _CharT, class _Traits, class _Allocator>
4275inline _LIBCPP_INLINE_VISIBILITY
4276basic_string<_CharT, _Traits, _Allocator>
4277operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4278{
4279    return _VSTD::move(__lhs.append(__rhs));
4280}
4281
4282template<class _CharT, class _Traits, class _Allocator>
4283inline _LIBCPP_INLINE_VISIBILITY
4284basic_string<_CharT, _Traits, _Allocator>
4285operator+(const _CharT* __lhs , basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4286{
4287    return _VSTD::move(__rhs.insert(0, __lhs));
4288}
4289
4290template<class _CharT, class _Traits, class _Allocator>
4291inline _LIBCPP_INLINE_VISIBILITY
4292basic_string<_CharT, _Traits, _Allocator>
4293operator+(_CharT __lhs, basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4294{
4295    __rhs.insert(__rhs.begin(), __lhs);
4296    return _VSTD::move(__rhs);
4297}
4298
4299template<class _CharT, class _Traits, class _Allocator>
4300inline _LIBCPP_INLINE_VISIBILITY
4301basic_string<_CharT, _Traits, _Allocator>
4302operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const _CharT* __rhs)
4303{
4304    return _VSTD::move(__lhs.append(__rhs));
4305}
4306
4307template<class _CharT, class _Traits, class _Allocator>
4308inline _LIBCPP_INLINE_VISIBILITY
4309basic_string<_CharT, _Traits, _Allocator>
4310operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, _CharT __rhs)
4311{
4312    __lhs.push_back(__rhs);
4313    return _VSTD::move(__lhs);
4314}
4315
4316#endif // _LIBCPP_CXX03_LANG
4317
4318// swap
4319
4320template<class _CharT, class _Traits, class _Allocator>
4321inline _LIBCPP_INLINE_VISIBILITY
4322void
4323swap(basic_string<_CharT, _Traits, _Allocator>& __lhs,
4324     basic_string<_CharT, _Traits, _Allocator>& __rhs)
4325     _NOEXCEPT_(_NOEXCEPT_(__lhs.swap(__rhs)))
4326{
4327    __lhs.swap(__rhs);
4328}
4329
4330_LIBCPP_FUNC_VIS int                stoi  (const string& __str, size_t* __idx = nullptr, int __base = 10);
4331_LIBCPP_FUNC_VIS long               stol  (const string& __str, size_t* __idx = nullptr, int __base = 10);
4332_LIBCPP_FUNC_VIS unsigned long      stoul (const string& __str, size_t* __idx = nullptr, int __base = 10);
4333_LIBCPP_FUNC_VIS long long          stoll (const string& __str, size_t* __idx = nullptr, int __base = 10);
4334_LIBCPP_FUNC_VIS unsigned long long stoull(const string& __str, size_t* __idx = nullptr, int __base = 10);
4335
4336_LIBCPP_FUNC_VIS float       stof (const string& __str, size_t* __idx = nullptr);
4337_LIBCPP_FUNC_VIS double      stod (const string& __str, size_t* __idx = nullptr);
4338_LIBCPP_FUNC_VIS long double stold(const string& __str, size_t* __idx = nullptr);
4339
4340_LIBCPP_FUNC_VIS string to_string(int __val);
4341_LIBCPP_FUNC_VIS string to_string(unsigned __val);
4342_LIBCPP_FUNC_VIS string to_string(long __val);
4343_LIBCPP_FUNC_VIS string to_string(unsigned long __val);
4344_LIBCPP_FUNC_VIS string to_string(long long __val);
4345_LIBCPP_FUNC_VIS string to_string(unsigned long long __val);
4346_LIBCPP_FUNC_VIS string to_string(float __val);
4347_LIBCPP_FUNC_VIS string to_string(double __val);
4348_LIBCPP_FUNC_VIS string to_string(long double __val);
4349
4350#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
4351_LIBCPP_FUNC_VIS int                stoi  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4352_LIBCPP_FUNC_VIS long               stol  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4353_LIBCPP_FUNC_VIS unsigned long      stoul (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4354_LIBCPP_FUNC_VIS long long          stoll (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4355_LIBCPP_FUNC_VIS unsigned long long stoull(const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4356
4357_LIBCPP_FUNC_VIS float       stof (const wstring& __str, size_t* __idx = nullptr);
4358_LIBCPP_FUNC_VIS double      stod (const wstring& __str, size_t* __idx = nullptr);
4359_LIBCPP_FUNC_VIS long double stold(const wstring& __str, size_t* __idx = nullptr);
4360
4361_LIBCPP_FUNC_VIS wstring to_wstring(int __val);
4362_LIBCPP_FUNC_VIS wstring to_wstring(unsigned __val);
4363_LIBCPP_FUNC_VIS wstring to_wstring(long __val);
4364_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long __val);
4365_LIBCPP_FUNC_VIS wstring to_wstring(long long __val);
4366_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long long __val);
4367_LIBCPP_FUNC_VIS wstring to_wstring(float __val);
4368_LIBCPP_FUNC_VIS wstring to_wstring(double __val);
4369_LIBCPP_FUNC_VIS wstring to_wstring(long double __val);
4370#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
4371
4372template<class _CharT, class _Traits, class _Allocator>
4373_LIBCPP_TEMPLATE_DATA_VIS
4374const typename basic_string<_CharT, _Traits, _Allocator>::size_type
4375               basic_string<_CharT, _Traits, _Allocator>::npos;
4376
4377template <class _CharT, class _Allocator>
4378struct _LIBCPP_TEMPLATE_VIS
4379    hash<basic_string<_CharT, char_traits<_CharT>, _Allocator> >
4380    : public unary_function<
4381          basic_string<_CharT, char_traits<_CharT>, _Allocator>, size_t>
4382{
4383    size_t
4384    operator()(const basic_string<_CharT, char_traits<_CharT>, _Allocator>& __val) const _NOEXCEPT
4385    { return __do_string_hash(__val.data(), __val.data() + __val.size()); }
4386};
4387
4388
4389template<class _CharT, class _Traits, class _Allocator>
4390basic_ostream<_CharT, _Traits>&
4391operator<<(basic_ostream<_CharT, _Traits>& __os,
4392           const basic_string<_CharT, _Traits, _Allocator>& __str);
4393
4394template<class _CharT, class _Traits, class _Allocator>
4395basic_istream<_CharT, _Traits>&
4396operator>>(basic_istream<_CharT, _Traits>& __is,
4397           basic_string<_CharT, _Traits, _Allocator>& __str);
4398
4399template<class _CharT, class _Traits, class _Allocator>
4400basic_istream<_CharT, _Traits>&
4401getline(basic_istream<_CharT, _Traits>& __is,
4402        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4403
4404template<class _CharT, class _Traits, class _Allocator>
4405inline _LIBCPP_INLINE_VISIBILITY
4406basic_istream<_CharT, _Traits>&
4407getline(basic_istream<_CharT, _Traits>& __is,
4408        basic_string<_CharT, _Traits, _Allocator>& __str);
4409
4410template<class _CharT, class _Traits, class _Allocator>
4411inline _LIBCPP_INLINE_VISIBILITY
4412basic_istream<_CharT, _Traits>&
4413getline(basic_istream<_CharT, _Traits>&& __is,
4414        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4415
4416template<class _CharT, class _Traits, class _Allocator>
4417inline _LIBCPP_INLINE_VISIBILITY
4418basic_istream<_CharT, _Traits>&
4419getline(basic_istream<_CharT, _Traits>&& __is,
4420        basic_string<_CharT, _Traits, _Allocator>& __str);
4421
4422#if _LIBCPP_STD_VER > 17
4423template <class _CharT, class _Traits, class _Allocator, class _Up>
4424inline _LIBCPP_INLINE_VISIBILITY
4425    typename basic_string<_CharT, _Traits, _Allocator>::size_type
4426    erase(basic_string<_CharT, _Traits, _Allocator>& __str, const _Up& __v) {
4427  auto __old_size = __str.size();
4428  __str.erase(_VSTD::remove(__str.begin(), __str.end(), __v), __str.end());
4429  return __old_size - __str.size();
4430}
4431
4432template <class _CharT, class _Traits, class _Allocator, class _Predicate>
4433inline _LIBCPP_INLINE_VISIBILITY
4434    typename basic_string<_CharT, _Traits, _Allocator>::size_type
4435    erase_if(basic_string<_CharT, _Traits, _Allocator>& __str,
4436             _Predicate __pred) {
4437  auto __old_size = __str.size();
4438  __str.erase(_VSTD::remove_if(__str.begin(), __str.end(), __pred),
4439              __str.end());
4440  return __old_size - __str.size();
4441}
4442#endif
4443
4444#if _LIBCPP_DEBUG_LEVEL == 2
4445
4446template<class _CharT, class _Traits, class _Allocator>
4447bool
4448basic_string<_CharT, _Traits, _Allocator>::__dereferenceable(const const_iterator* __i) const
4449{
4450    return this->data() <= _VSTD::__to_address(__i->base()) &&
4451           _VSTD::__to_address(__i->base()) < this->data() + this->size();
4452}
4453
4454template<class _CharT, class _Traits, class _Allocator>
4455bool
4456basic_string<_CharT, _Traits, _Allocator>::__decrementable(const const_iterator* __i) const
4457{
4458    return this->data() < _VSTD::__to_address(__i->base()) &&
4459           _VSTD::__to_address(__i->base()) <= this->data() + this->size();
4460}
4461
4462template<class _CharT, class _Traits, class _Allocator>
4463bool
4464basic_string<_CharT, _Traits, _Allocator>::__addable(const const_iterator* __i, ptrdiff_t __n) const
4465{
4466    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4467    return this->data() <= __p && __p <= this->data() + this->size();
4468}
4469
4470template<class _CharT, class _Traits, class _Allocator>
4471bool
4472basic_string<_CharT, _Traits, _Allocator>::__subscriptable(const const_iterator* __i, ptrdiff_t __n) const
4473{
4474    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4475    return this->data() <= __p && __p < this->data() + this->size();
4476}
4477
4478#endif // _LIBCPP_DEBUG_LEVEL == 2
4479
4480#if _LIBCPP_STD_VER > 11
4481// Literal suffixes for basic_string [basic.string.literals]
4482inline namespace literals
4483{
4484  inline namespace string_literals
4485  {
4486    inline _LIBCPP_INLINE_VISIBILITY
4487    basic_string<char> operator "" s( const char *__str, size_t __len )
4488    {
4489        return basic_string<char> (__str, __len);
4490    }
4491
4492#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
4493    inline _LIBCPP_INLINE_VISIBILITY
4494    basic_string<wchar_t> operator "" s( const wchar_t *__str, size_t __len )
4495    {
4496        return basic_string<wchar_t> (__str, __len);
4497    }
4498#endif
4499
4500#ifndef _LIBCPP_HAS_NO_CHAR8_T
4501    inline _LIBCPP_INLINE_VISIBILITY
4502    basic_string<char8_t> operator "" s(const char8_t *__str, size_t __len) _NOEXCEPT
4503    {
4504        return basic_string<char8_t> (__str, __len);
4505    }
4506#endif
4507
4508    inline _LIBCPP_INLINE_VISIBILITY
4509    basic_string<char16_t> operator "" s( const char16_t *__str, size_t __len )
4510    {
4511        return basic_string<char16_t> (__str, __len);
4512    }
4513
4514    inline _LIBCPP_INLINE_VISIBILITY
4515    basic_string<char32_t> operator "" s( const char32_t *__str, size_t __len )
4516    {
4517        return basic_string<char32_t> (__str, __len);
4518    }
4519  } // namespace string_literals
4520} // namespace literals
4521#endif
4522
4523_LIBCPP_END_NAMESPACE_STD
4524
4525_LIBCPP_POP_MACROS
4526
4527#endif // _LIBCPP_STRING
4528