xref: /freebsd/contrib/llvm-project/libcxx/include/string (revision 0eae32dcef82f6f06de6419a0d623d7def0cc8f6)
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    void reserve(size_type res_arg);
162    void reserve(); // deprecated in C++20
163    void shrink_to_fit();
164    void clear() noexcept;
165    bool empty() const noexcept;
166
167    const_reference operator[](size_type pos) const;
168    reference       operator[](size_type pos);
169
170    const_reference at(size_type n) const;
171    reference       at(size_type n);
172
173    basic_string& operator+=(const basic_string& str);
174    template <class T>
175        basic_string& operator+=(const T& t);              // C++17
176    basic_string& operator+=(const value_type* s);
177    basic_string& operator+=(value_type c);
178    basic_string& operator+=(initializer_list<value_type>);
179
180    basic_string& append(const basic_string& str);
181    template <class T>
182        basic_string& append(const T& t);                 // C++17
183    basic_string& append(const basic_string& str, size_type pos, size_type n=npos); //C++14
184    template <class T>
185        basic_string& append(const T& t, size_type pos, size_type n=npos); // C++17
186    basic_string& append(const value_type* s, size_type n);
187    basic_string& append(const value_type* s);
188    basic_string& append(size_type n, value_type c);
189    template<class InputIterator>
190        basic_string& append(InputIterator first, InputIterator last);
191    basic_string& append(initializer_list<value_type>);
192
193    void push_back(value_type c);
194    void pop_back();
195    reference       front();
196    const_reference front() const;
197    reference       back();
198    const_reference back() const;
199
200    basic_string& assign(const basic_string& str);
201    template <class T>
202        basic_string& assign(const T& t);  // C++17
203    basic_string& assign(basic_string&& str);
204    basic_string& assign(const basic_string& str, size_type pos, size_type n=npos); // C++14
205    template <class T>
206        basic_string& assign(const T& t, size_type pos, size_type n=npos); // C++17
207    basic_string& assign(const value_type* s, size_type n);
208    basic_string& assign(const value_type* s);
209    basic_string& assign(size_type n, value_type c);
210    template<class InputIterator>
211        basic_string& assign(InputIterator first, InputIterator last);
212    basic_string& assign(initializer_list<value_type>);
213
214    basic_string& insert(size_type pos1, const basic_string& str);
215    template <class T>
216        basic_string& insert(size_type pos1, const T& t);
217    basic_string& insert(size_type pos1, const basic_string& str,
218                         size_type pos2, size_type n);
219    template <class T>
220        basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n); // C++17
221    basic_string& insert(size_type pos, const value_type* s, size_type n=npos); //C++14
222    basic_string& insert(size_type pos, const value_type* s);
223    basic_string& insert(size_type pos, size_type n, value_type c);
224    iterator      insert(const_iterator p, value_type c);
225    iterator      insert(const_iterator p, size_type n, value_type c);
226    template<class InputIterator>
227        iterator insert(const_iterator p, InputIterator first, InputIterator last);
228    iterator      insert(const_iterator p, initializer_list<value_type>);
229
230    basic_string& erase(size_type pos = 0, size_type n = npos);
231    iterator      erase(const_iterator position);
232    iterator      erase(const_iterator first, const_iterator last);
233
234    basic_string& replace(size_type pos1, size_type n1, const basic_string& str);
235    template <class T>
236    basic_string& replace(size_type pos1, size_type n1, const T& t);  // C++17
237    basic_string& replace(size_type pos1, size_type n1, const basic_string& str,
238                          size_type pos2, size_type n2=npos); // C++14
239    template <class T>
240        basic_string& replace(size_type pos1, size_type n1, const T& t,
241                              size_type pos2, size_type n); // C++17
242    basic_string& replace(size_type pos, size_type n1, const value_type* s, size_type n2);
243    basic_string& replace(size_type pos, size_type n1, const value_type* s);
244    basic_string& replace(size_type pos, size_type n1, size_type n2, value_type c);
245    basic_string& replace(const_iterator i1, const_iterator i2, const basic_string& str);
246    template <class T>
247        basic_string& replace(const_iterator i1, const_iterator i2, const T& t);  // C++17
248    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s, size_type n);
249    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s);
250    basic_string& replace(const_iterator i1, const_iterator i2, size_type n, value_type c);
251    template<class InputIterator>
252        basic_string& replace(const_iterator i1, const_iterator i2, InputIterator j1, InputIterator j2);
253    basic_string& replace(const_iterator i1, const_iterator i2, initializer_list<value_type>);
254
255    size_type copy(value_type* s, size_type n, size_type pos = 0) const;
256    basic_string substr(size_type pos = 0, size_type n = npos) const;
257
258    void swap(basic_string& str)
259        noexcept(allocator_traits<allocator_type>::propagate_on_container_swap::value ||
260                 allocator_traits<allocator_type>::is_always_equal::value);  // C++17
261
262    const value_type* c_str() const noexcept;
263    const value_type* data() const noexcept;
264          value_type* data()       noexcept;   // C++17
265
266    allocator_type get_allocator() const noexcept;
267
268    size_type find(const basic_string& str, size_type pos = 0) const noexcept;
269    template <class T>
270        size_type find(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
271    size_type find(const value_type* s, size_type pos, size_type n) const noexcept;
272    size_type find(const value_type* s, size_type pos = 0) const noexcept;
273    size_type find(value_type c, size_type pos = 0) const noexcept;
274
275    size_type rfind(const basic_string& str, size_type pos = npos) const noexcept;
276    template <class T>
277        size_type rfind(const T& t, size_type pos = npos) const noexcept; // C++17, noexcept as an extension
278    size_type rfind(const value_type* s, size_type pos, size_type n) const noexcept;
279    size_type rfind(const value_type* s, size_type pos = npos) const noexcept;
280    size_type rfind(value_type c, size_type pos = npos) const noexcept;
281
282    size_type find_first_of(const basic_string& str, size_type pos = 0) const noexcept;
283    template <class T>
284        size_type find_first_of(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
285    size_type find_first_of(const value_type* s, size_type pos, size_type n) const noexcept;
286    size_type find_first_of(const value_type* s, size_type pos = 0) const noexcept;
287    size_type find_first_of(value_type c, size_type pos = 0) const noexcept;
288
289    size_type find_last_of(const basic_string& str, size_type pos = npos) const noexcept;
290    template <class T>
291        size_type find_last_of(const T& t, size_type pos = npos) const noexcept noexcept; // C++17, noexcept as an extension
292    size_type find_last_of(const value_type* s, size_type pos, size_type n) const noexcept;
293    size_type find_last_of(const value_type* s, size_type pos = npos) const noexcept;
294    size_type find_last_of(value_type c, size_type pos = npos) const noexcept;
295
296    size_type find_first_not_of(const basic_string& str, size_type pos = 0) const noexcept;
297    template <class T>
298        size_type find_first_not_of(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
299    size_type find_first_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
300    size_type find_first_not_of(const value_type* s, size_type pos = 0) const noexcept;
301    size_type find_first_not_of(value_type c, size_type pos = 0) const noexcept;
302
303    size_type find_last_not_of(const basic_string& str, size_type pos = npos) const noexcept;
304    template <class T>
305        size_type find_last_not_of(const T& t, size_type pos = npos) const noexcept; // C++17, noexcept as an extension
306    size_type find_last_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
307    size_type find_last_not_of(const value_type* s, size_type pos = npos) const noexcept;
308    size_type find_last_not_of(value_type c, size_type pos = npos) const noexcept;
309
310    int compare(const basic_string& str) const noexcept;
311    template <class T>
312        int compare(const T& t) const noexcept;  // C++17, noexcept as an extension
313    int compare(size_type pos1, size_type n1, const basic_string& str) const;
314    template <class T>
315        int compare(size_type pos1, size_type n1, const T& t) const;  // C++17
316    int compare(size_type pos1, size_type n1, const basic_string& str,
317                size_type pos2, size_type n2=npos) const; // C++14
318    template <class T>
319        int compare(size_type pos1, size_type n1, const T& t,
320                    size_type pos2, size_type n2=npos) const; // C++17
321    int compare(const value_type* s) const noexcept;
322    int compare(size_type pos1, size_type n1, const value_type* s) const;
323    int compare(size_type pos1, size_type n1, const value_type* s, size_type n2) const;
324
325    bool starts_with(basic_string_view<charT, traits> sv) const noexcept; // C++20
326    bool starts_with(charT c) const noexcept;                             // C++20
327    bool starts_with(const charT* s) const;                               // C++20
328    bool ends_with(basic_string_view<charT, traits> sv) const noexcept;   // C++20
329    bool ends_with(charT c) const noexcept;                               // C++20
330    bool ends_with(const charT* s) const;                                 // C++20
331
332    constexpr bool contains(basic_string_view<charT, traits> sv) const noexcept; // C++2b
333    constexpr bool contains(charT c) const noexcept;                             // C++2b
334    constexpr bool contains(const charT* s) const;                               // C++2b
335
336    bool __invariants() const;
337};
338
339template<class InputIterator,
340         class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
341basic_string(InputIterator, InputIterator, Allocator = Allocator())
342   -> basic_string<typename iterator_traits<InputIterator>::value_type,
343                  char_traits<typename iterator_traits<InputIterator>::value_type>,
344                  Allocator>;   // C++17
345
346template<class charT, class traits, class Allocator>
347basic_string<charT, traits, Allocator>
348operator+(const basic_string<charT, traits, Allocator>& lhs,
349          const basic_string<charT, traits, Allocator>& rhs);
350
351template<class charT, class traits, class Allocator>
352basic_string<charT, traits, Allocator>
353operator+(const charT* lhs , const basic_string<charT,traits,Allocator>&rhs);
354
355template<class charT, class traits, class Allocator>
356basic_string<charT, traits, Allocator>
357operator+(charT lhs, const basic_string<charT,traits,Allocator>& rhs);
358
359template<class charT, class traits, class Allocator>
360basic_string<charT, traits, Allocator>
361operator+(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs);
362
363template<class charT, class traits, class Allocator>
364basic_string<charT, traits, Allocator>
365operator+(const basic_string<charT, traits, Allocator>& lhs, charT rhs);
366
367template<class charT, class traits, class Allocator>
368bool operator==(const basic_string<charT, traits, Allocator>& lhs,
369                const basic_string<charT, traits, Allocator>& rhs) noexcept;
370
371template<class charT, class traits, class Allocator>
372bool operator==(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
373
374template<class charT, class traits, class Allocator>
375bool operator==(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs) noexcept;
376
377template<class charT, class traits, class Allocator>
378bool operator!=(const basic_string<charT,traits,Allocator>& lhs,
379                const basic_string<charT, traits, Allocator>& rhs) noexcept;
380
381template<class charT, class traits, class Allocator>
382bool operator!=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
383
384template<class charT, class traits, class Allocator>
385bool operator!=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
386
387template<class charT, class traits, class Allocator>
388bool operator< (const basic_string<charT, traits, Allocator>& lhs,
389                const basic_string<charT, traits, Allocator>& rhs) noexcept;
390
391template<class charT, class traits, class Allocator>
392bool operator< (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
393
394template<class charT, class traits, class Allocator>
395bool operator< (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
396
397template<class charT, class traits, class Allocator>
398bool operator> (const basic_string<charT, traits, Allocator>& lhs,
399                const basic_string<charT, traits, Allocator>& rhs) noexcept;
400
401template<class charT, class traits, class Allocator>
402bool operator> (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
403
404template<class charT, class traits, class Allocator>
405bool operator> (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
406
407template<class charT, class traits, class Allocator>
408bool operator<=(const basic_string<charT, traits, Allocator>& lhs,
409                const basic_string<charT, traits, Allocator>& rhs) noexcept;
410
411template<class charT, class traits, class Allocator>
412bool operator<=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
413
414template<class charT, class traits, class Allocator>
415bool operator<=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
416
417template<class charT, class traits, class Allocator>
418bool operator>=(const basic_string<charT, traits, Allocator>& lhs,
419                const basic_string<charT, traits, Allocator>& rhs) noexcept;
420
421template<class charT, class traits, class Allocator>
422bool operator>=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
423
424template<class charT, class traits, class Allocator>
425bool operator>=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
426
427template<class charT, class traits, class Allocator>
428void swap(basic_string<charT, traits, Allocator>& lhs,
429          basic_string<charT, traits, Allocator>& rhs)
430            noexcept(noexcept(lhs.swap(rhs)));
431
432template<class charT, class traits, class Allocator>
433basic_istream<charT, traits>&
434operator>>(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);
435
436template<class charT, class traits, class Allocator>
437basic_ostream<charT, traits>&
438operator<<(basic_ostream<charT, traits>& os, const basic_string<charT, traits, Allocator>& str);
439
440template<class charT, class traits, class Allocator>
441basic_istream<charT, traits>&
442getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str,
443        charT delim);
444
445template<class charT, class traits, class Allocator>
446basic_istream<charT, traits>&
447getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);
448
449template<class charT, class traits, class Allocator, class U>
450typename basic_string<charT, traits, Allocator>::size_type
451erase(basic_string<charT, traits, Allocator>& c, const U& value);    // C++20
452template<class charT, class traits, class Allocator, class Predicate>
453typename basic_string<charT, traits, Allocator>::size_type
454erase_if(basic_string<charT, traits, Allocator>& c, Predicate pred); // C++20
455
456typedef basic_string<char>    string;
457typedef basic_string<wchar_t> wstring;
458typedef basic_string<char8_t> u8string; // C++20
459typedef basic_string<char16_t> u16string;
460typedef basic_string<char32_t> u32string;
461
462int                stoi  (const string& str, size_t* idx = nullptr, int base = 10);
463long               stol  (const string& str, size_t* idx = nullptr, int base = 10);
464unsigned long      stoul (const string& str, size_t* idx = nullptr, int base = 10);
465long long          stoll (const string& str, size_t* idx = nullptr, int base = 10);
466unsigned long long stoull(const string& str, size_t* idx = nullptr, int base = 10);
467
468float       stof (const string& str, size_t* idx = nullptr);
469double      stod (const string& str, size_t* idx = nullptr);
470long double stold(const string& str, size_t* idx = nullptr);
471
472string to_string(int val);
473string to_string(unsigned val);
474string to_string(long val);
475string to_string(unsigned long val);
476string to_string(long long val);
477string to_string(unsigned long long val);
478string to_string(float val);
479string to_string(double val);
480string to_string(long double val);
481
482int                stoi  (const wstring& str, size_t* idx = nullptr, int base = 10);
483long               stol  (const wstring& str, size_t* idx = nullptr, int base = 10);
484unsigned long      stoul (const wstring& str, size_t* idx = nullptr, int base = 10);
485long long          stoll (const wstring& str, size_t* idx = nullptr, int base = 10);
486unsigned long long stoull(const wstring& str, size_t* idx = nullptr, int base = 10);
487
488float       stof (const wstring& str, size_t* idx = nullptr);
489double      stod (const wstring& str, size_t* idx = nullptr);
490long double stold(const wstring& str, size_t* idx = nullptr);
491
492wstring to_wstring(int val);
493wstring to_wstring(unsigned val);
494wstring to_wstring(long val);
495wstring to_wstring(unsigned long val);
496wstring to_wstring(long long val);
497wstring to_wstring(unsigned long long val);
498wstring to_wstring(float val);
499wstring to_wstring(double val);
500wstring to_wstring(long double val);
501
502template <> struct hash<string>;
503template <> struct hash<u8string>; // C++20
504template <> struct hash<u16string>;
505template <> struct hash<u32string>;
506template <> struct hash<wstring>;
507
508basic_string<char>     operator "" s( const char *str,     size_t len ); // C++14
509basic_string<wchar_t>  operator "" s( const wchar_t *str,  size_t len ); // C++14
510basic_string<char8_t>  operator "" s( const char8_t *str,  size_t len ); // C++20
511basic_string<char16_t> operator "" s( const char16_t *str, size_t len ); // C++14
512basic_string<char32_t> operator "" s( const char32_t *str, size_t len ); // C++14
513
514}  // std
515
516*/
517
518#include <__config>
519#include <__debug>
520#include <__functional_base>
521#include <__iterator/wrap_iter.h>
522#include <algorithm>
523#include <compare>
524#include <cstdio>  // EOF
525#include <cstdlib>
526#include <cstring>
527#include <initializer_list>
528#include <iosfwd>
529#include <iterator>
530#include <memory>
531#include <stdexcept>
532#include <string_view>
533#include <type_traits>
534#include <utility>
535#include <version>
536
537#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
538#   include <cwchar>
539#endif
540
541#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
542# include <cstdint>
543#endif
544
545#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
546#pragma GCC system_header
547#endif
548
549_LIBCPP_PUSH_MACROS
550#include <__undef_macros>
551
552
553_LIBCPP_BEGIN_NAMESPACE_STD
554
555// fpos
556
557template <class _StateT>
558class _LIBCPP_TEMPLATE_VIS fpos
559{
560private:
561    _StateT __st_;
562    streamoff __off_;
563public:
564    _LIBCPP_INLINE_VISIBILITY fpos(streamoff __off = streamoff()) : __st_(), __off_(__off) {}
565
566    _LIBCPP_INLINE_VISIBILITY operator streamoff() const {return __off_;}
567
568    _LIBCPP_INLINE_VISIBILITY _StateT state() const {return __st_;}
569    _LIBCPP_INLINE_VISIBILITY void state(_StateT __st) {__st_ = __st;}
570
571    _LIBCPP_INLINE_VISIBILITY fpos& operator+=(streamoff __off) {__off_ += __off; return *this;}
572    _LIBCPP_INLINE_VISIBILITY fpos  operator+ (streamoff __off) const {fpos __t(*this); __t += __off; return __t;}
573    _LIBCPP_INLINE_VISIBILITY fpos& operator-=(streamoff __off) {__off_ -= __off; return *this;}
574    _LIBCPP_INLINE_VISIBILITY fpos  operator- (streamoff __off) const {fpos __t(*this); __t -= __off; return __t;}
575};
576
577template <class _StateT>
578inline _LIBCPP_INLINE_VISIBILITY
579streamoff operator-(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
580    {return streamoff(__x) - streamoff(__y);}
581
582template <class _StateT>
583inline _LIBCPP_INLINE_VISIBILITY
584bool operator==(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
585    {return streamoff(__x) == streamoff(__y);}
586
587template <class _StateT>
588inline _LIBCPP_INLINE_VISIBILITY
589bool operator!=(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
590    {return streamoff(__x) != streamoff(__y);}
591
592// basic_string
593
594template<class _CharT, class _Traits, class _Allocator>
595basic_string<_CharT, _Traits, _Allocator>
596operator+(const basic_string<_CharT, _Traits, _Allocator>& __x,
597          const basic_string<_CharT, _Traits, _Allocator>& __y);
598
599template<class _CharT, class _Traits, class _Allocator>
600basic_string<_CharT, _Traits, _Allocator>
601operator+(const _CharT* __x, const basic_string<_CharT,_Traits,_Allocator>& __y);
602
603template<class _CharT, class _Traits, class _Allocator>
604basic_string<_CharT, _Traits, _Allocator>
605operator+(_CharT __x, const basic_string<_CharT,_Traits,_Allocator>& __y);
606
607template<class _CharT, class _Traits, class _Allocator>
608inline _LIBCPP_INLINE_VISIBILITY
609basic_string<_CharT, _Traits, _Allocator>
610operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, const _CharT* __y);
611
612template<class _CharT, class _Traits, class _Allocator>
613basic_string<_CharT, _Traits, _Allocator>
614operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, _CharT __y);
615
616_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS string operator+<char, char_traits<char>, allocator<char> >(char const*, string const&))
617
618template <bool>
619struct __basic_string_common;
620
621template <>
622struct __basic_string_common<true> {
623    // Both are defined in string.cpp
624    _LIBCPP_NORETURN _LIBCPP_EXPORTED_FROM_ABI void __throw_length_error() const;
625    _LIBCPP_NORETURN _LIBCPP_EXPORTED_FROM_ABI void __throw_out_of_range() const;
626};
627
628template <class _Iter>
629struct __string_is_trivial_iterator : public false_type {};
630
631template <class _Tp>
632struct __string_is_trivial_iterator<_Tp*>
633    : public is_arithmetic<_Tp> {};
634
635template <class _Iter>
636struct __string_is_trivial_iterator<__wrap_iter<_Iter> >
637    : public __string_is_trivial_iterator<_Iter> {};
638
639template <class _CharT, class _Traits, class _Tp>
640struct __can_be_converted_to_string_view : public _BoolConstant<
641      is_convertible<const _Tp&, basic_string_view<_CharT, _Traits> >::value &&
642     !is_convertible<const _Tp&, const _CharT*>::value
643    > {};
644
645#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
646
647template <class _CharT, size_t = sizeof(_CharT)>
648struct __padding
649{
650    unsigned char __xx[sizeof(_CharT)-1];
651};
652
653template <class _CharT>
654struct __padding<_CharT, 1>
655{
656};
657
658#endif // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
659
660#ifndef _LIBCPP_HAS_NO_CHAR8_T
661typedef basic_string<char8_t> u8string;
662#endif
663
664#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
665typedef basic_string<char16_t> u16string;
666typedef basic_string<char32_t> u32string;
667#endif
668
669template<class _CharT, class _Traits, class _Allocator>
670class
671    _LIBCPP_TEMPLATE_VIS
672#ifndef _LIBCPP_HAS_NO_CHAR8_T
673    _LIBCPP_PREFERRED_NAME(u8string)
674#endif
675#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
676    _LIBCPP_PREFERRED_NAME(u16string)
677    _LIBCPP_PREFERRED_NAME(u32string)
678#endif
679    basic_string
680    : private __basic_string_common<true> // This base class is historical, but it needs to remain for ABI compatibility
681{
682public:
683    typedef basic_string                                 __self;
684    typedef basic_string_view<_CharT, _Traits>           __self_view;
685    typedef _Traits                                      traits_type;
686    typedef _CharT                                       value_type;
687    typedef _Allocator                                   allocator_type;
688    typedef allocator_traits<allocator_type>             __alloc_traits;
689    typedef typename __alloc_traits::size_type           size_type;
690    typedef typename __alloc_traits::difference_type     difference_type;
691    typedef value_type&                                  reference;
692    typedef const value_type&                            const_reference;
693    typedef typename __alloc_traits::pointer             pointer;
694    typedef typename __alloc_traits::const_pointer       const_pointer;
695
696    static_assert((!is_array<value_type>::value), "Character type of basic_string must not be an array");
697    static_assert(( is_standard_layout<value_type>::value), "Character type of basic_string must be standard-layout");
698    static_assert(( is_trivial<value_type>::value), "Character type of basic_string must be trivial");
699    static_assert(( is_same<_CharT, typename traits_type::char_type>::value),
700                  "traits_type::char_type must be the same type as CharT");
701    static_assert(( is_same<typename allocator_type::value_type, value_type>::value),
702                  "Allocator::value_type must be same type as value_type");
703
704    typedef __wrap_iter<pointer>                         iterator;
705    typedef __wrap_iter<const_pointer>                   const_iterator;
706    typedef _VSTD::reverse_iterator<iterator>             reverse_iterator;
707    typedef _VSTD::reverse_iterator<const_iterator>       const_reverse_iterator;
708
709private:
710
711#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
712
713    struct __long
714    {
715        pointer   __data_;
716        size_type __size_;
717        size_type __cap_;
718    };
719
720#ifdef _LIBCPP_BIG_ENDIAN
721    static const size_type __short_mask = 0x01;
722    static const size_type __long_mask  = 0x1ul;
723#else  // _LIBCPP_BIG_ENDIAN
724    static const size_type __short_mask = 0x80;
725    static const size_type __long_mask  = ~(size_type(~0) >> 1);
726#endif // _LIBCPP_BIG_ENDIAN
727
728    enum {__min_cap = (sizeof(__long) - 1)/sizeof(value_type) > 2 ?
729                      (sizeof(__long) - 1)/sizeof(value_type) : 2};
730
731    struct __short
732    {
733        value_type __data_[__min_cap];
734        struct
735            : __padding<value_type>
736        {
737            unsigned char __size_;
738        };
739    };
740
741#else
742
743    struct __long
744    {
745        size_type __cap_;
746        size_type __size_;
747        pointer   __data_;
748    };
749
750#ifdef _LIBCPP_BIG_ENDIAN
751    static const size_type __short_mask = 0x80;
752    static const size_type __long_mask  = ~(size_type(~0) >> 1);
753#else  // _LIBCPP_BIG_ENDIAN
754    static const size_type __short_mask = 0x01;
755    static const size_type __long_mask  = 0x1ul;
756#endif // _LIBCPP_BIG_ENDIAN
757
758    enum {__min_cap = (sizeof(__long) - 1)/sizeof(value_type) > 2 ?
759                      (sizeof(__long) - 1)/sizeof(value_type) : 2};
760
761    struct __short
762    {
763        union
764        {
765            unsigned char __size_;
766            value_type __lx;
767        };
768        value_type __data_[__min_cap];
769    };
770
771#endif // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
772
773    union __ulx{__long __lx; __short __lxx;};
774
775    enum {__n_words = sizeof(__ulx) / sizeof(size_type)};
776
777    struct __raw
778    {
779        size_type __words[__n_words];
780    };
781
782    struct __rep
783    {
784        union
785        {
786            __long  __l;
787            __short __s;
788            __raw   __r;
789        };
790    };
791
792    __compressed_pair<__rep, allocator_type> __r_;
793
794public:
795    _LIBCPP_TEMPLATE_DATA_VIS
796    static const size_type npos = -1;
797
798    _LIBCPP_INLINE_VISIBILITY basic_string()
799        _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
800
801    _LIBCPP_INLINE_VISIBILITY explicit basic_string(const allocator_type& __a)
802#if _LIBCPP_STD_VER <= 14
803        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value);
804#else
805        _NOEXCEPT;
806#endif
807
808    basic_string(const basic_string& __str);
809    basic_string(const basic_string& __str, const allocator_type& __a);
810
811#ifndef _LIBCPP_CXX03_LANG
812    _LIBCPP_INLINE_VISIBILITY
813    basic_string(basic_string&& __str)
814#if _LIBCPP_STD_VER <= 14
815        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
816#else
817        _NOEXCEPT;
818#endif
819
820    _LIBCPP_INLINE_VISIBILITY
821    basic_string(basic_string&& __str, const allocator_type& __a);
822#endif // _LIBCPP_CXX03_LANG
823
824    template <class = __enable_if_t<__is_allocator<_Allocator>::value, nullptr_t> >
825    _LIBCPP_INLINE_VISIBILITY
826    basic_string(const _CharT* __s) : __r_(__default_init_tag(), __default_init_tag()) {
827      _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*) detected nullptr");
828      __init(__s, traits_type::length(__s));
829#if _LIBCPP_DEBUG_LEVEL == 2
830        if (!__libcpp_is_constant_evaluated())
831            __get_db()->__insert_c(this);
832#endif
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    _LIBCPP_INLINE_VISIBILITY void __resize_default_init(size_type __n);
977
978    _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_INLINE_VISIBILITY
979    void reserve() _NOEXCEPT {shrink_to_fit();}
980    _LIBCPP_INLINE_VISIBILITY
981    void shrink_to_fit() _NOEXCEPT;
982    _LIBCPP_INLINE_VISIBILITY
983    void clear() _NOEXCEPT;
984    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
985    bool empty() const _NOEXCEPT {return size() == 0;}
986
987    _LIBCPP_INLINE_VISIBILITY const_reference operator[](size_type __pos) const _NOEXCEPT;
988    _LIBCPP_INLINE_VISIBILITY reference       operator[](size_type __pos)       _NOEXCEPT;
989
990    const_reference at(size_type __n) const;
991    reference       at(size_type __n);
992
993    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const basic_string& __str) {return append(__str);}
994
995    template <class _Tp>
996    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
997    __enable_if_t
998        <
999            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1000            && !__is_same_uncvref<_Tp, basic_string >::value,
1001            basic_string&
1002        >
1003                                            operator+=(const _Tp& __t)            {__self_view __sv = __t; return append(__sv);}
1004    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const value_type* __s)     {return append(__s);}
1005    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(value_type __c)            {push_back(__c); return *this;}
1006#ifndef _LIBCPP_CXX03_LANG
1007    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(initializer_list<value_type> __il) {return append(__il);}
1008#endif // _LIBCPP_CXX03_LANG
1009
1010    _LIBCPP_INLINE_VISIBILITY
1011    basic_string& append(const basic_string& __str);
1012
1013    template <class _Tp>
1014    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1015    __enable_if_t<
1016            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1017            && !__is_same_uncvref<_Tp, basic_string>::value,
1018            basic_string&
1019        >
1020                  append(const _Tp& __t) { __self_view __sv = __t; return append(__sv.data(), __sv.size()); }
1021    basic_string& append(const basic_string& __str, size_type __pos, size_type __n=npos);
1022
1023    template <class _Tp>
1024    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1025    __enable_if_t
1026        <
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, size_type __pos, size_type __n=npos);
1032    basic_string& append(const value_type* __s, size_type __n);
1033    basic_string& append(const value_type* __s);
1034    basic_string& append(size_type __n, value_type __c);
1035
1036    _LIBCPP_INLINE_VISIBILITY
1037    void __append_default_init(size_type __n);
1038
1039    template<class _InputIterator>
1040    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1041    __enable_if_t
1042        <
1043            __is_exactly_cpp17_input_iterator<_InputIterator>::value,
1044            basic_string&
1045        >
1046    _LIBCPP_INLINE_VISIBILITY
1047    append(_InputIterator __first, _InputIterator __last) {
1048      const basic_string __temp(__first, __last, __alloc());
1049      append(__temp.data(), __temp.size());
1050      return *this;
1051    }
1052    template<class _ForwardIterator>
1053    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1054    __enable_if_t
1055        <
1056            __is_cpp17_forward_iterator<_ForwardIterator>::value,
1057            basic_string&
1058        >
1059    _LIBCPP_INLINE_VISIBILITY
1060    append(_ForwardIterator __first, _ForwardIterator __last);
1061
1062#ifndef _LIBCPP_CXX03_LANG
1063    _LIBCPP_INLINE_VISIBILITY
1064    basic_string& append(initializer_list<value_type> __il) {return append(__il.begin(), __il.size());}
1065#endif // _LIBCPP_CXX03_LANG
1066
1067    void push_back(value_type __c);
1068    _LIBCPP_INLINE_VISIBILITY
1069    void pop_back();
1070    _LIBCPP_INLINE_VISIBILITY reference       front() _NOEXCEPT;
1071    _LIBCPP_INLINE_VISIBILITY const_reference front() const _NOEXCEPT;
1072    _LIBCPP_INLINE_VISIBILITY reference       back() _NOEXCEPT;
1073    _LIBCPP_INLINE_VISIBILITY const_reference back() const _NOEXCEPT;
1074
1075    template <class _Tp>
1076    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1077    __enable_if_t
1078        <
1079            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1080            basic_string&
1081        >
1082                 assign(const _Tp & __t) { __self_view __sv = __t; return assign(__sv.data(), __sv.size()); }
1083    _LIBCPP_INLINE_VISIBILITY
1084    basic_string& assign(const basic_string& __str) { return *this = __str; }
1085#ifndef _LIBCPP_CXX03_LANG
1086    _LIBCPP_INLINE_VISIBILITY
1087    basic_string& assign(basic_string&& __str)
1088        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
1089        {*this = _VSTD::move(__str); return *this;}
1090#endif
1091    basic_string& assign(const basic_string& __str, size_type __pos, size_type __n=npos);
1092    template <class _Tp>
1093    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1094    __enable_if_t
1095        <
1096            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1097            && !__is_same_uncvref<_Tp, basic_string>::value,
1098            basic_string&
1099        >
1100                  assign(const _Tp & __t, size_type __pos, size_type __n=npos);
1101    basic_string& assign(const value_type* __s, size_type __n);
1102    basic_string& assign(const value_type* __s);
1103    basic_string& assign(size_type __n, value_type __c);
1104    template<class _InputIterator>
1105    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1106    __enable_if_t
1107        <
1108            __is_exactly_cpp17_input_iterator<_InputIterator>::value,
1109            basic_string&
1110        >
1111        assign(_InputIterator __first, _InputIterator __last);
1112    template<class _ForwardIterator>
1113    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1114    __enable_if_t
1115        <
1116            __is_cpp17_forward_iterator<_ForwardIterator>::value,
1117            basic_string&
1118        >
1119        assign(_ForwardIterator __first, _ForwardIterator __last);
1120#ifndef _LIBCPP_CXX03_LANG
1121    _LIBCPP_INLINE_VISIBILITY
1122    basic_string& assign(initializer_list<value_type> __il) {return assign(__il.begin(), __il.size());}
1123#endif // _LIBCPP_CXX03_LANG
1124
1125    _LIBCPP_INLINE_VISIBILITY
1126    basic_string& insert(size_type __pos1, const basic_string& __str);
1127
1128    template <class _Tp>
1129    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1130    __enable_if_t
1131        <
1132            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1133            basic_string&
1134        >
1135                 insert(size_type __pos1, const _Tp& __t)
1136    { __self_view __sv = __t; return insert(__pos1, __sv.data(), __sv.size()); }
1137
1138    template <class _Tp>
1139    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1140    __enable_if_t
1141        <
1142            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value,
1143            basic_string&
1144        >
1145                  insert(size_type __pos1, const _Tp& __t, size_type __pos2, size_type __n=npos);
1146    basic_string& insert(size_type __pos1, const basic_string& __str, size_type __pos2, size_type __n=npos);
1147    basic_string& insert(size_type __pos, const value_type* __s, size_type __n);
1148    basic_string& insert(size_type __pos, const value_type* __s);
1149    basic_string& insert(size_type __pos, size_type __n, value_type __c);
1150    iterator      insert(const_iterator __pos, value_type __c);
1151    _LIBCPP_INLINE_VISIBILITY
1152    iterator      insert(const_iterator __pos, size_type __n, value_type __c);
1153    template<class _InputIterator>
1154    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1155    __enable_if_t
1156        <
1157            __is_exactly_cpp17_input_iterator<_InputIterator>::value,
1158            iterator
1159        >
1160        insert(const_iterator __pos, _InputIterator __first, _InputIterator __last);
1161    template<class _ForwardIterator>
1162    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1163    __enable_if_t
1164        <
1165            __is_cpp17_forward_iterator<_ForwardIterator>::value,
1166            iterator
1167        >
1168        insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last);
1169#ifndef _LIBCPP_CXX03_LANG
1170    _LIBCPP_INLINE_VISIBILITY
1171    iterator insert(const_iterator __pos, initializer_list<value_type> __il)
1172                    {return insert(__pos, __il.begin(), __il.end());}
1173#endif // _LIBCPP_CXX03_LANG
1174
1175    basic_string& erase(size_type __pos = 0, size_type __n = npos);
1176    _LIBCPP_INLINE_VISIBILITY
1177    iterator      erase(const_iterator __pos);
1178    _LIBCPP_INLINE_VISIBILITY
1179    iterator      erase(const_iterator __first, const_iterator __last);
1180
1181    _LIBCPP_INLINE_VISIBILITY
1182    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str);
1183
1184    template <class _Tp>
1185    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1186    __enable_if_t
1187        <
1188            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1189            basic_string&
1190        >
1191                  replace(size_type __pos1, size_type __n1, const _Tp& __t) { __self_view __sv = __t; return replace(__pos1, __n1, __sv.data(), __sv.size()); }
1192    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos);
1193    template <class _Tp>
1194    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1195    __enable_if_t
1196        <
1197            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
1198            basic_string&
1199        >
1200                  replace(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos);
1201    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2);
1202    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s);
1203    basic_string& replace(size_type __pos, size_type __n1, size_type __n2, value_type __c);
1204    _LIBCPP_INLINE_VISIBILITY
1205    basic_string& replace(const_iterator __i1, const_iterator __i2, const basic_string& __str);
1206
1207    template <class _Tp>
1208    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1209    __enable_if_t
1210        <
1211            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1212            basic_string&
1213        >
1214                  replace(const_iterator __i1, const_iterator __i2, const _Tp& __t) { __self_view __sv = __t; return replace(__i1 - begin(), __i2 - __i1, __sv); }
1215
1216    _LIBCPP_INLINE_VISIBILITY
1217    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n);
1218    _LIBCPP_INLINE_VISIBILITY
1219    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s);
1220    _LIBCPP_INLINE_VISIBILITY
1221    basic_string& replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c);
1222    template<class _InputIterator>
1223    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1224    __enable_if_t
1225        <
1226            __is_cpp17_input_iterator<_InputIterator>::value,
1227            basic_string&
1228        >
1229        replace(const_iterator __i1, const_iterator __i2, _InputIterator __j1, _InputIterator __j2);
1230#ifndef _LIBCPP_CXX03_LANG
1231    _LIBCPP_INLINE_VISIBILITY
1232    basic_string& replace(const_iterator __i1, const_iterator __i2, initializer_list<value_type> __il)
1233        {return replace(__i1, __i2, __il.begin(), __il.end());}
1234#endif // _LIBCPP_CXX03_LANG
1235
1236    size_type copy(value_type* __s, size_type __n, size_type __pos = 0) const;
1237    _LIBCPP_INLINE_VISIBILITY
1238    basic_string substr(size_type __pos = 0, size_type __n = npos) const;
1239
1240    _LIBCPP_INLINE_VISIBILITY
1241    void swap(basic_string& __str)
1242#if _LIBCPP_STD_VER >= 14
1243        _NOEXCEPT;
1244#else
1245        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
1246                    __is_nothrow_swappable<allocator_type>::value);
1247#endif
1248
1249    _LIBCPP_INLINE_VISIBILITY
1250    const value_type* c_str() const _NOEXCEPT {return data();}
1251    _LIBCPP_INLINE_VISIBILITY
1252    const value_type* data() const _NOEXCEPT  {return _VSTD::__to_address(__get_pointer());}
1253#if _LIBCPP_STD_VER > 14 || defined(_LIBCPP_BUILDING_LIBRARY)
1254    _LIBCPP_INLINE_VISIBILITY
1255    value_type* data()             _NOEXCEPT  {return _VSTD::__to_address(__get_pointer());}
1256#endif
1257
1258    _LIBCPP_INLINE_VISIBILITY
1259    allocator_type get_allocator() const _NOEXCEPT {return __alloc();}
1260
1261    _LIBCPP_INLINE_VISIBILITY
1262    size_type find(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1263
1264    template <class _Tp>
1265    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1266    __enable_if_t
1267        <
1268            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1269            size_type
1270        >
1271              find(const _Tp& __t, size_type __pos = 0) const _NOEXCEPT;
1272    size_type find(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1273    _LIBCPP_INLINE_VISIBILITY
1274    size_type find(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1275    size_type find(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1276
1277    _LIBCPP_INLINE_VISIBILITY
1278    size_type rfind(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1279
1280    template <class _Tp>
1281    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1282    __enable_if_t
1283        <
1284            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1285            size_type
1286        >
1287              rfind(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1288    size_type rfind(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1289    _LIBCPP_INLINE_VISIBILITY
1290    size_type rfind(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1291    size_type rfind(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1292
1293    _LIBCPP_INLINE_VISIBILITY
1294    size_type find_first_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1295
1296    template <class _Tp>
1297    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1298    __enable_if_t
1299        <
1300            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1301            size_type
1302        >
1303              find_first_of(const _Tp& __t, size_type __pos = 0) const _NOEXCEPT;
1304    size_type find_first_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1305    _LIBCPP_INLINE_VISIBILITY
1306    size_type find_first_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1307    _LIBCPP_INLINE_VISIBILITY
1308    size_type find_first_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1309
1310    _LIBCPP_INLINE_VISIBILITY
1311    size_type find_last_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1312
1313    template <class _Tp>
1314    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1315    __enable_if_t
1316        <
1317            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1318            size_type
1319        >
1320              find_last_of(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1321    size_type find_last_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1322    _LIBCPP_INLINE_VISIBILITY
1323    size_type find_last_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1324    _LIBCPP_INLINE_VISIBILITY
1325    size_type find_last_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1326
1327    _LIBCPP_INLINE_VISIBILITY
1328    size_type find_first_not_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1329
1330    template <class _Tp>
1331    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1332    __enable_if_t
1333        <
1334            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1335            size_type
1336        >
1337              find_first_not_of(const _Tp &__t, size_type __pos = 0) const _NOEXCEPT;
1338    size_type find_first_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1339    _LIBCPP_INLINE_VISIBILITY
1340    size_type find_first_not_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1341    _LIBCPP_INLINE_VISIBILITY
1342    size_type find_first_not_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1343
1344    _LIBCPP_INLINE_VISIBILITY
1345    size_type find_last_not_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1346
1347    template <class _Tp>
1348    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1349    __enable_if_t
1350        <
1351            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1352            size_type
1353        >
1354              find_last_not_of(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1355    size_type find_last_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1356    _LIBCPP_INLINE_VISIBILITY
1357    size_type find_last_not_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1358    _LIBCPP_INLINE_VISIBILITY
1359    size_type find_last_not_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1360
1361    _LIBCPP_INLINE_VISIBILITY
1362    int compare(const basic_string& __str) const _NOEXCEPT;
1363
1364    template <class _Tp>
1365    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1366    __enable_if_t
1367        <
1368            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1369            int
1370        >
1371        compare(const _Tp &__t) const _NOEXCEPT;
1372
1373    template <class _Tp>
1374    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1375    __enable_if_t
1376        <
1377            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1378            int
1379        >
1380         compare(size_type __pos1, size_type __n1, const _Tp& __t) const;
1381
1382    _LIBCPP_INLINE_VISIBILITY
1383    int compare(size_type __pos1, size_type __n1, const basic_string& __str) const;
1384    int compare(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos) const;
1385
1386    template <class _Tp>
1387    inline _LIBCPP_INLINE_VISIBILITY
1388        __enable_if_t
1389        <
1390            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
1391            int
1392        >
1393        compare(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos) const;
1394    int compare(const value_type* __s) const _NOEXCEPT;
1395    int compare(size_type __pos1, size_type __n1, const value_type* __s) const;
1396    int compare(size_type __pos1, size_type __n1, const value_type* __s, size_type __n2) const;
1397
1398#if _LIBCPP_STD_VER > 17
1399    constexpr _LIBCPP_INLINE_VISIBILITY
1400    bool starts_with(__self_view __sv) const noexcept
1401    { return __self_view(data(), size()).starts_with(__sv); }
1402
1403    constexpr _LIBCPP_INLINE_VISIBILITY
1404    bool starts_with(value_type __c) const noexcept
1405    { return !empty() && _Traits::eq(front(), __c); }
1406
1407    constexpr _LIBCPP_INLINE_VISIBILITY
1408    bool starts_with(const value_type* __s) const noexcept
1409    { return starts_with(__self_view(__s)); }
1410
1411    constexpr _LIBCPP_INLINE_VISIBILITY
1412    bool ends_with(__self_view __sv) const noexcept
1413    { return __self_view(data(), size()).ends_with( __sv); }
1414
1415    constexpr _LIBCPP_INLINE_VISIBILITY
1416    bool ends_with(value_type __c) const noexcept
1417    { return !empty() && _Traits::eq(back(), __c); }
1418
1419    constexpr _LIBCPP_INLINE_VISIBILITY
1420    bool ends_with(const value_type* __s) const noexcept
1421    { return ends_with(__self_view(__s)); }
1422#endif
1423
1424#if _LIBCPP_STD_VER > 20
1425    constexpr _LIBCPP_INLINE_VISIBILITY
1426    bool contains(__self_view __sv) const noexcept
1427    { return __self_view(data(), size()).contains(__sv); }
1428
1429    constexpr _LIBCPP_INLINE_VISIBILITY
1430    bool contains(value_type __c) const noexcept
1431    { return __self_view(data(), size()).contains(__c); }
1432
1433    constexpr _LIBCPP_INLINE_VISIBILITY
1434    bool contains(const value_type* __s) const
1435    { return __self_view(data(), size()).contains(__s); }
1436#endif
1437
1438    _LIBCPP_INLINE_VISIBILITY bool __invariants() const;
1439
1440    _LIBCPP_INLINE_VISIBILITY void __clear_and_shrink() _NOEXCEPT;
1441
1442    _LIBCPP_INLINE_VISIBILITY void __shrink_or_extend(size_type __target_capacity);
1443
1444    _LIBCPP_INLINE_VISIBILITY
1445    bool __is_long() const _NOEXCEPT
1446        {return bool(__r_.first().__s.__size_ & __short_mask);}
1447
1448#if _LIBCPP_DEBUG_LEVEL == 2
1449
1450    bool __dereferenceable(const const_iterator* __i) const;
1451    bool __decrementable(const const_iterator* __i) const;
1452    bool __addable(const const_iterator* __i, ptrdiff_t __n) const;
1453    bool __subscriptable(const const_iterator* __i, ptrdiff_t __n) const;
1454
1455#endif // _LIBCPP_DEBUG_LEVEL == 2
1456
1457private:
1458    _LIBCPP_INLINE_VISIBILITY
1459    allocator_type& __alloc() _NOEXCEPT
1460        {return __r_.second();}
1461    _LIBCPP_INLINE_VISIBILITY
1462    const allocator_type& __alloc() const _NOEXCEPT
1463        {return __r_.second();}
1464
1465#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1466
1467    _LIBCPP_INLINE_VISIBILITY
1468    void __set_short_size(size_type __s) _NOEXCEPT
1469#   ifdef _LIBCPP_BIG_ENDIAN
1470        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
1471#   else
1472        {__r_.first().__s.__size_ = (unsigned char)(__s);}
1473#   endif
1474
1475    _LIBCPP_INLINE_VISIBILITY
1476    size_type __get_short_size() const _NOEXCEPT
1477#   ifdef _LIBCPP_BIG_ENDIAN
1478        {return __r_.first().__s.__size_ >> 1;}
1479#   else
1480        {return __r_.first().__s.__size_;}
1481#   endif
1482
1483#else  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1484
1485    _LIBCPP_INLINE_VISIBILITY
1486    void __set_short_size(size_type __s) _NOEXCEPT
1487#   ifdef _LIBCPP_BIG_ENDIAN
1488        {__r_.first().__s.__size_ = (unsigned char)(__s);}
1489#   else
1490        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
1491#   endif
1492
1493    _LIBCPP_INLINE_VISIBILITY
1494    size_type __get_short_size() const _NOEXCEPT
1495#   ifdef _LIBCPP_BIG_ENDIAN
1496        {return __r_.first().__s.__size_;}
1497#   else
1498        {return __r_.first().__s.__size_ >> 1;}
1499#   endif
1500
1501#endif // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1502
1503    _LIBCPP_INLINE_VISIBILITY
1504    void __set_long_size(size_type __s) _NOEXCEPT
1505        {__r_.first().__l.__size_ = __s;}
1506    _LIBCPP_INLINE_VISIBILITY
1507    size_type __get_long_size() const _NOEXCEPT
1508        {return __r_.first().__l.__size_;}
1509    _LIBCPP_INLINE_VISIBILITY
1510    void __set_size(size_type __s) _NOEXCEPT
1511        {if (__is_long()) __set_long_size(__s); else __set_short_size(__s);}
1512
1513    _LIBCPP_INLINE_VISIBILITY
1514    void __set_long_cap(size_type __s) _NOEXCEPT
1515        {__r_.first().__l.__cap_  = __long_mask | __s;}
1516    _LIBCPP_INLINE_VISIBILITY
1517    size_type __get_long_cap() const _NOEXCEPT
1518        {return __r_.first().__l.__cap_ & size_type(~__long_mask);}
1519
1520    _LIBCPP_INLINE_VISIBILITY
1521    void __set_long_pointer(pointer __p) _NOEXCEPT
1522        {__r_.first().__l.__data_ = __p;}
1523    _LIBCPP_INLINE_VISIBILITY
1524    pointer __get_long_pointer() _NOEXCEPT
1525        {return __r_.first().__l.__data_;}
1526    _LIBCPP_INLINE_VISIBILITY
1527    const_pointer __get_long_pointer() const _NOEXCEPT
1528        {return __r_.first().__l.__data_;}
1529    _LIBCPP_INLINE_VISIBILITY
1530    pointer __get_short_pointer() _NOEXCEPT
1531        {return pointer_traits<pointer>::pointer_to(__r_.first().__s.__data_[0]);}
1532    _LIBCPP_INLINE_VISIBILITY
1533    const_pointer __get_short_pointer() const _NOEXCEPT
1534        {return pointer_traits<const_pointer>::pointer_to(__r_.first().__s.__data_[0]);}
1535    _LIBCPP_INLINE_VISIBILITY
1536    pointer __get_pointer() _NOEXCEPT
1537        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
1538    _LIBCPP_INLINE_VISIBILITY
1539    const_pointer __get_pointer() const _NOEXCEPT
1540        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
1541
1542    _LIBCPP_INLINE_VISIBILITY
1543    void __zero() _NOEXCEPT
1544        {
1545            size_type (&__a)[__n_words] = __r_.first().__r.__words;
1546            for (unsigned __i = 0; __i < __n_words; ++__i)
1547                __a[__i] = 0;
1548        }
1549
1550    template <size_type __a> static
1551        _LIBCPP_INLINE_VISIBILITY
1552        size_type __align_it(size_type __s) _NOEXCEPT
1553            {return (__s + (__a-1)) & ~(__a-1);}
1554    enum {__alignment = 16};
1555    static _LIBCPP_INLINE_VISIBILITY
1556    size_type __recommend(size_type __s) _NOEXCEPT
1557        {
1558        if (__s < __min_cap) return static_cast<size_type>(__min_cap) - 1;
1559        size_type __guess = __align_it<sizeof(value_type) < __alignment ?
1560                     __alignment/sizeof(value_type) : 1 > (__s+1) - 1;
1561        if (__guess == __min_cap) ++__guess;
1562        return __guess;
1563        }
1564
1565    inline
1566    void __init(const value_type* __s, size_type __sz, size_type __reserve);
1567    inline
1568    void __init(const value_type* __s, size_type __sz);
1569    inline
1570    void __init(size_type __n, value_type __c);
1571
1572    // Slow path for the (inlined) copy constructor for 'long' strings.
1573    // Always externally instantiated and not inlined.
1574    // Requires that __s is zero terminated.
1575    // The main reason for this function to exist is because for unstable, we
1576    // want to allow inlining of the copy constructor. However, we don't want
1577    // to call the __init() functions as those are marked as inline which may
1578    // result in over-aggressive inlining by the compiler, where our aim is
1579    // to only inline the fast path code directly in the ctor.
1580    void __init_copy_ctor_external(const value_type* __s, size_type __sz);
1581
1582    template <class _InputIterator>
1583    inline
1584    __enable_if_t
1585    <
1586        __is_exactly_cpp17_input_iterator<_InputIterator>::value
1587    >
1588    __init(_InputIterator __first, _InputIterator __last);
1589
1590    template <class _ForwardIterator>
1591    inline
1592    __enable_if_t
1593    <
1594        __is_cpp17_forward_iterator<_ForwardIterator>::value
1595    >
1596    __init(_ForwardIterator __first, _ForwardIterator __last);
1597
1598    void __grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1599                   size_type __n_copy,  size_type __n_del,     size_type __n_add = 0);
1600    void __grow_by_and_replace(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1601                               size_type __n_copy,  size_type __n_del,
1602                               size_type __n_add, const value_type* __p_new_stuff);
1603
1604    // __assign_no_alias is invoked for assignment operations where we
1605    // have proof that the input does not alias the current instance.
1606    // For example, operator=(basic_string) performs a 'self' check.
1607    template <bool __is_short>
1608    basic_string& __assign_no_alias(const value_type* __s, size_type __n);
1609
1610    _LIBCPP_INLINE_VISIBILITY
1611    void __erase_to_end(size_type __pos);
1612
1613    // __erase_external_with_move is invoked for erase() invocations where
1614    // `n ~= npos`, likely requiring memory moves on the string data.
1615    void __erase_external_with_move(size_type __pos, size_type __n);
1616
1617    _LIBCPP_INLINE_VISIBILITY
1618    void __copy_assign_alloc(const basic_string& __str)
1619        {__copy_assign_alloc(__str, integral_constant<bool,
1620                      __alloc_traits::propagate_on_container_copy_assignment::value>());}
1621
1622    _LIBCPP_INLINE_VISIBILITY
1623    void __copy_assign_alloc(const basic_string& __str, true_type)
1624        {
1625            if (__alloc() == __str.__alloc())
1626                __alloc() = __str.__alloc();
1627            else
1628            {
1629                if (!__str.__is_long())
1630                {
1631                    __clear_and_shrink();
1632                    __alloc() = __str.__alloc();
1633                }
1634                else
1635                {
1636                    allocator_type __a = __str.__alloc();
1637                    pointer __p = __alloc_traits::allocate(__a, __str.__get_long_cap());
1638                    __clear_and_shrink();
1639                    __alloc() = _VSTD::move(__a);
1640                    __set_long_pointer(__p);
1641                    __set_long_cap(__str.__get_long_cap());
1642                    __set_long_size(__str.size());
1643                }
1644            }
1645        }
1646
1647    _LIBCPP_INLINE_VISIBILITY
1648    void __copy_assign_alloc(const basic_string&, false_type) _NOEXCEPT
1649        {}
1650
1651#ifndef _LIBCPP_CXX03_LANG
1652    _LIBCPP_INLINE_VISIBILITY
1653    void __move_assign(basic_string& __str, false_type)
1654        _NOEXCEPT_(__alloc_traits::is_always_equal::value);
1655    _LIBCPP_INLINE_VISIBILITY
1656    void __move_assign(basic_string& __str, true_type)
1657#if _LIBCPP_STD_VER > 14
1658        _NOEXCEPT;
1659#else
1660        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
1661#endif
1662#endif
1663
1664    _LIBCPP_INLINE_VISIBILITY
1665    void
1666    __move_assign_alloc(basic_string& __str)
1667        _NOEXCEPT_(
1668            !__alloc_traits::propagate_on_container_move_assignment::value ||
1669            is_nothrow_move_assignable<allocator_type>::value)
1670    {__move_assign_alloc(__str, integral_constant<bool,
1671                      __alloc_traits::propagate_on_container_move_assignment::value>());}
1672
1673    _LIBCPP_INLINE_VISIBILITY
1674    void __move_assign_alloc(basic_string& __c, true_type)
1675        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
1676        {
1677            __alloc() = _VSTD::move(__c.__alloc());
1678        }
1679
1680    _LIBCPP_INLINE_VISIBILITY
1681    void __move_assign_alloc(basic_string&, false_type)
1682        _NOEXCEPT
1683        {}
1684
1685    basic_string& __assign_external(const value_type* __s);
1686    basic_string& __assign_external(const value_type* __s, size_type __n);
1687
1688    // Assigns the value in __s, guaranteed to be __n < __min_cap in length.
1689    inline basic_string& __assign_short(const value_type* __s, size_type __n) {
1690      pointer __p = __is_long()
1691                        ? (__set_long_size(__n), __get_long_pointer())
1692                        : (__set_short_size(__n), __get_short_pointer());
1693      traits_type::move(_VSTD::__to_address(__p), __s, __n);
1694      traits_type::assign(__p[__n], value_type());
1695      return *this;
1696    }
1697
1698    _LIBCPP_HIDE_FROM_ABI basic_string& __null_terminate_at(value_type* __p, size_type __newsz) {
1699      __set_size(__newsz);
1700      __invalidate_iterators_past(__newsz);
1701      traits_type::assign(__p[__newsz], value_type());
1702      return *this;
1703    }
1704
1705    _LIBCPP_INLINE_VISIBILITY void __invalidate_all_iterators();
1706    _LIBCPP_INLINE_VISIBILITY void __invalidate_iterators_past(size_type);
1707
1708    template<class _Tp>
1709    _LIBCPP_INLINE_VISIBILITY
1710    bool __addr_in_range(_Tp&& __t) const {
1711        const volatile void *__p = _VSTD::addressof(__t);
1712        return data() <= __p && __p <= data() + size();
1713    }
1714
1715    _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI
1716    void __throw_length_error() const {
1717#ifndef _LIBCPP_NO_EXCEPTIONS
1718        __basic_string_common<true>::__throw_length_error();
1719#else
1720        _VSTD::abort();
1721#endif
1722    }
1723
1724    _LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI
1725    void __throw_out_of_range() const {
1726#ifndef _LIBCPP_NO_EXCEPTIONS
1727        __basic_string_common<true>::__throw_out_of_range();
1728#else
1729        _VSTD::abort();
1730#endif
1731    }
1732
1733    friend basic_string operator+<>(const basic_string&, const basic_string&);
1734    friend basic_string operator+<>(const value_type*, const basic_string&);
1735    friend basic_string operator+<>(value_type, const basic_string&);
1736    friend basic_string operator+<>(const basic_string&, const value_type*);
1737    friend basic_string operator+<>(const basic_string&, value_type);
1738};
1739
1740// These declarations must appear before any functions are implicitly used
1741// so that they have the correct visibility specifier.
1742#ifdef _LIBCPP_ABI_STRING_OPTIMIZED_EXTERNAL_INSTANTIATION
1743    _LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
1744#   ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
1745        _LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
1746#   endif
1747#else
1748    _LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
1749#   ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
1750        _LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
1751#   endif
1752#endif
1753
1754
1755#if _LIBCPP_STD_VER >= 17
1756template<class _InputIterator,
1757         class _CharT = __iter_value_type<_InputIterator>,
1758         class _Allocator = allocator<_CharT>,
1759         class = enable_if_t<__is_cpp17_input_iterator<_InputIterator>::value>,
1760         class = enable_if_t<__is_allocator<_Allocator>::value>
1761         >
1762basic_string(_InputIterator, _InputIterator, _Allocator = _Allocator())
1763  -> basic_string<_CharT, char_traits<_CharT>, _Allocator>;
1764
1765template<class _CharT,
1766         class _Traits,
1767         class _Allocator = allocator<_CharT>,
1768         class = enable_if_t<__is_allocator<_Allocator>::value>
1769         >
1770explicit basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
1771  -> basic_string<_CharT, _Traits, _Allocator>;
1772
1773template<class _CharT,
1774         class _Traits,
1775         class _Allocator = allocator<_CharT>,
1776         class = enable_if_t<__is_allocator<_Allocator>::value>,
1777         class _Sz = typename allocator_traits<_Allocator>::size_type
1778         >
1779basic_string(basic_string_view<_CharT, _Traits>, _Sz, _Sz, const _Allocator& = _Allocator())
1780  -> basic_string<_CharT, _Traits, _Allocator>;
1781#endif
1782
1783template <class _CharT, class _Traits, class _Allocator>
1784inline
1785void
1786basic_string<_CharT, _Traits, _Allocator>::__invalidate_all_iterators()
1787{
1788#if _LIBCPP_DEBUG_LEVEL == 2
1789    if (!__libcpp_is_constant_evaluated())
1790        __get_db()->__invalidate_all(this);
1791#endif
1792}
1793
1794template <class _CharT, class _Traits, class _Allocator>
1795inline
1796void
1797basic_string<_CharT, _Traits, _Allocator>::__invalidate_iterators_past(size_type __pos)
1798{
1799#if _LIBCPP_DEBUG_LEVEL == 2
1800    if (!__libcpp_is_constant_evaluated()) {
1801        __c_node* __c = __get_db()->__find_c_and_lock(this);
1802        if (__c)
1803        {
1804            const_pointer __new_last = __get_pointer() + __pos;
1805            for (__i_node** __p = __c->end_; __p != __c->beg_; )
1806            {
1807                --__p;
1808                const_iterator* __i = static_cast<const_iterator*>((*__p)->__i_);
1809                if (__i->base() > __new_last)
1810                {
1811                    (*__p)->__c_ = nullptr;
1812                    if (--__c->end_ != __p)
1813                        _VSTD::memmove(__p, __p+1, (__c->end_ - __p)*sizeof(__i_node*));
1814                }
1815            }
1816            __get_db()->unlock();
1817        }
1818    }
1819#else
1820    (void)__pos;
1821#endif // _LIBCPP_DEBUG_LEVEL == 2
1822}
1823
1824template <class _CharT, class _Traits, class _Allocator>
1825inline
1826basic_string<_CharT, _Traits, _Allocator>::basic_string()
1827    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
1828     : __r_(__default_init_tag(), __default_init_tag())
1829{
1830#if _LIBCPP_DEBUG_LEVEL == 2
1831    if (!__libcpp_is_constant_evaluated())
1832        __get_db()->__insert_c(this);
1833#endif
1834    __zero();
1835}
1836
1837template <class _CharT, class _Traits, class _Allocator>
1838inline
1839basic_string<_CharT, _Traits, _Allocator>::basic_string(const allocator_type& __a)
1840#if _LIBCPP_STD_VER <= 14
1841        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value)
1842#else
1843        _NOEXCEPT
1844#endif
1845: __r_(__default_init_tag(), __a)
1846{
1847#if _LIBCPP_DEBUG_LEVEL == 2
1848    if (!__libcpp_is_constant_evaluated())
1849        __get_db()->__insert_c(this);
1850#endif
1851    __zero();
1852}
1853
1854template <class _CharT, class _Traits, class _Allocator>
1855void basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s,
1856                                                       size_type __sz,
1857                                                       size_type __reserve)
1858{
1859    if (__reserve > max_size())
1860        this->__throw_length_error();
1861    pointer __p;
1862    if (__reserve < __min_cap)
1863    {
1864        __set_short_size(__sz);
1865        __p = __get_short_pointer();
1866    }
1867    else
1868    {
1869        size_type __cap = __recommend(__reserve);
1870        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1871        __set_long_pointer(__p);
1872        __set_long_cap(__cap+1);
1873        __set_long_size(__sz);
1874    }
1875    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1876    traits_type::assign(__p[__sz], value_type());
1877}
1878
1879template <class _CharT, class _Traits, class _Allocator>
1880void
1881basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s, size_type __sz)
1882{
1883    if (__sz > max_size())
1884        this->__throw_length_error();
1885    pointer __p;
1886    if (__sz < __min_cap)
1887    {
1888        __set_short_size(__sz);
1889        __p = __get_short_pointer();
1890    }
1891    else
1892    {
1893        size_type __cap = __recommend(__sz);
1894        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1895        __set_long_pointer(__p);
1896        __set_long_cap(__cap+1);
1897        __set_long_size(__sz);
1898    }
1899    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1900    traits_type::assign(__p[__sz], value_type());
1901}
1902
1903template <class _CharT, class _Traits, class _Allocator>
1904template <class>
1905basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, const _Allocator& __a)
1906    : __r_(__default_init_tag(), __a)
1907{
1908    _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*, allocator) detected nullptr");
1909    __init(__s, traits_type::length(__s));
1910#if _LIBCPP_DEBUG_LEVEL == 2
1911    if (!__libcpp_is_constant_evaluated())
1912        __get_db()->__insert_c(this);
1913#endif
1914}
1915
1916template <class _CharT, class _Traits, class _Allocator>
1917inline
1918basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n)
1919     : __r_(__default_init_tag(), __default_init_tag())
1920{
1921      _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n) detected nullptr");
1922      __init(__s, __n);
1923#if _LIBCPP_DEBUG_LEVEL == 2
1924    if (!__libcpp_is_constant_evaluated())
1925        __get_db()->__insert_c(this);
1926#endif
1927}
1928
1929template <class _CharT, class _Traits, class _Allocator>
1930inline
1931basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n, const _Allocator& __a)
1932    : __r_(__default_init_tag(), __a)
1933{
1934    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n, allocator) detected nullptr");
1935    __init(__s, __n);
1936#if _LIBCPP_DEBUG_LEVEL == 2
1937    if (!__libcpp_is_constant_evaluated())
1938        __get_db()->__insert_c(this);
1939#endif
1940}
1941
1942template <class _CharT, class _Traits, class _Allocator>
1943basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str)
1944    : __r_(__default_init_tag(), __alloc_traits::select_on_container_copy_construction(__str.__alloc()))
1945{
1946    if (!__str.__is_long())
1947        __r_.first().__r = __str.__r_.first().__r;
1948    else
1949        __init_copy_ctor_external(_VSTD::__to_address(__str.__get_long_pointer()),
1950                                  __str.__get_long_size());
1951
1952#if _LIBCPP_DEBUG_LEVEL == 2
1953    if (!__libcpp_is_constant_evaluated())
1954        __get_db()->__insert_c(this);
1955#endif
1956}
1957
1958template <class _CharT, class _Traits, class _Allocator>
1959basic_string<_CharT, _Traits, _Allocator>::basic_string(
1960    const basic_string& __str, const allocator_type& __a)
1961    : __r_(__default_init_tag(), __a)
1962{
1963    if (!__str.__is_long())
1964        __r_.first().__r = __str.__r_.first().__r;
1965    else
1966        __init_copy_ctor_external(_VSTD::__to_address(__str.__get_long_pointer()),
1967                                  __str.__get_long_size());
1968#if _LIBCPP_DEBUG_LEVEL == 2
1969    if (!__libcpp_is_constant_evaluated())
1970        __get_db()->__insert_c(this);
1971#endif
1972}
1973
1974template <class _CharT, class _Traits, class _Allocator>
1975void basic_string<_CharT, _Traits, _Allocator>::__init_copy_ctor_external(
1976    const value_type* __s, size_type __sz) {
1977  pointer __p;
1978  if (__sz < __min_cap) {
1979    __p = __get_short_pointer();
1980    __set_short_size(__sz);
1981  } else {
1982    if (__sz > max_size())
1983      this->__throw_length_error();
1984    size_t __cap = __recommend(__sz);
1985    __p = __alloc_traits::allocate(__alloc(), __cap + 1);
1986    __set_long_pointer(__p);
1987    __set_long_cap(__cap + 1);
1988    __set_long_size(__sz);
1989  }
1990  traits_type::copy(_VSTD::__to_address(__p), __s, __sz + 1);
1991}
1992
1993#ifndef _LIBCPP_CXX03_LANG
1994
1995template <class _CharT, class _Traits, class _Allocator>
1996inline
1997basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str)
1998#if _LIBCPP_STD_VER <= 14
1999        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
2000#else
2001        _NOEXCEPT
2002#endif
2003    : __r_(_VSTD::move(__str.__r_))
2004{
2005    __str.__zero();
2006#if _LIBCPP_DEBUG_LEVEL == 2
2007    if (!__libcpp_is_constant_evaluated()) {
2008        __get_db()->__insert_c(this);
2009        if (__is_long())
2010            __get_db()->swap(this, &__str);
2011    }
2012#endif
2013}
2014
2015template <class _CharT, class _Traits, class _Allocator>
2016inline
2017basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str, const allocator_type& __a)
2018    : __r_(__default_init_tag(), __a)
2019{
2020    if (__str.__is_long() && __a != __str.__alloc()) // copy, not move
2021        __init(_VSTD::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
2022    else
2023    {
2024        __r_.first().__r = __str.__r_.first().__r;
2025        __str.__zero();
2026    }
2027#if _LIBCPP_DEBUG_LEVEL == 2
2028    if (!__libcpp_is_constant_evaluated()) {
2029        __get_db()->__insert_c(this);
2030        if (__is_long())
2031            __get_db()->swap(this, &__str);
2032    }
2033#endif
2034}
2035
2036#endif // _LIBCPP_CXX03_LANG
2037
2038template <class _CharT, class _Traits, class _Allocator>
2039void
2040basic_string<_CharT, _Traits, _Allocator>::__init(size_type __n, value_type __c)
2041{
2042    if (__n > max_size())
2043        this->__throw_length_error();
2044    pointer __p;
2045    if (__n < __min_cap)
2046    {
2047        __set_short_size(__n);
2048        __p = __get_short_pointer();
2049    }
2050    else
2051    {
2052        size_type __cap = __recommend(__n);
2053        __p = __alloc_traits::allocate(__alloc(), __cap+1);
2054        __set_long_pointer(__p);
2055        __set_long_cap(__cap+1);
2056        __set_long_size(__n);
2057    }
2058    traits_type::assign(_VSTD::__to_address(__p), __n, __c);
2059    traits_type::assign(__p[__n], value_type());
2060}
2061
2062template <class _CharT, class _Traits, class _Allocator>
2063inline
2064basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c)
2065     : __r_(__default_init_tag(), __default_init_tag())
2066{
2067    __init(__n, __c);
2068#if _LIBCPP_DEBUG_LEVEL == 2
2069    if (!__libcpp_is_constant_evaluated())
2070        __get_db()->__insert_c(this);
2071#endif
2072}
2073
2074template <class _CharT, class _Traits, class _Allocator>
2075template <class>
2076basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c, const _Allocator& __a)
2077    : __r_(__default_init_tag(), __a)
2078{
2079    __init(__n, __c);
2080#if _LIBCPP_DEBUG_LEVEL == 2
2081    if (!__libcpp_is_constant_evaluated())
2082        __get_db()->__insert_c(this);
2083#endif
2084}
2085
2086template <class _CharT, class _Traits, class _Allocator>
2087basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str,
2088                                                        size_type __pos, size_type __n,
2089                                                        const _Allocator& __a)
2090    : __r_(__default_init_tag(), __a)
2091{
2092    size_type __str_sz = __str.size();
2093    if (__pos > __str_sz)
2094        this->__throw_out_of_range();
2095    __init(__str.data() + __pos, _VSTD::min(__n, __str_sz - __pos));
2096#if _LIBCPP_DEBUG_LEVEL == 2
2097    if (!__libcpp_is_constant_evaluated())
2098        __get_db()->__insert_c(this);
2099#endif
2100}
2101
2102template <class _CharT, class _Traits, class _Allocator>
2103inline
2104basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str, size_type __pos,
2105                                                        const _Allocator& __a)
2106    : __r_(__default_init_tag(), __a)
2107{
2108    size_type __str_sz = __str.size();
2109    if (__pos > __str_sz)
2110        this->__throw_out_of_range();
2111    __init(__str.data() + __pos, __str_sz - __pos);
2112#if _LIBCPP_DEBUG_LEVEL == 2
2113    if (!__libcpp_is_constant_evaluated())
2114        __get_db()->__insert_c(this);
2115#endif
2116}
2117
2118template <class _CharT, class _Traits, class _Allocator>
2119template <class _Tp, class>
2120basic_string<_CharT, _Traits, _Allocator>::basic_string(
2121             const _Tp& __t, size_type __pos, size_type __n, const allocator_type& __a)
2122    : __r_(__default_init_tag(), __a)
2123{
2124    __self_view __sv0 = __t;
2125    __self_view __sv = __sv0.substr(__pos, __n);
2126    __init(__sv.data(), __sv.size());
2127#if _LIBCPP_DEBUG_LEVEL == 2
2128    if (!__libcpp_is_constant_evaluated())
2129        __get_db()->__insert_c(this);
2130#endif
2131}
2132
2133template <class _CharT, class _Traits, class _Allocator>
2134template <class _Tp, class>
2135basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t)
2136     : __r_(__default_init_tag(), __default_init_tag())
2137{
2138    __self_view __sv = __t;
2139    __init(__sv.data(), __sv.size());
2140#if _LIBCPP_DEBUG_LEVEL == 2
2141    if (!__libcpp_is_constant_evaluated())
2142        __get_db()->__insert_c(this);
2143#endif
2144}
2145
2146template <class _CharT, class _Traits, class _Allocator>
2147template <class _Tp, class>
2148basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t, const _Allocator& __a)
2149    : __r_(__default_init_tag(), __a)
2150{
2151    __self_view __sv = __t;
2152    __init(__sv.data(), __sv.size());
2153#if _LIBCPP_DEBUG_LEVEL == 2
2154    if (!__libcpp_is_constant_evaluated())
2155        __get_db()->__insert_c(this);
2156#endif
2157}
2158
2159template <class _CharT, class _Traits, class _Allocator>
2160template <class _InputIterator>
2161__enable_if_t
2162<
2163    __is_exactly_cpp17_input_iterator<_InputIterator>::value
2164>
2165basic_string<_CharT, _Traits, _Allocator>::__init(_InputIterator __first, _InputIterator __last)
2166{
2167    __zero();
2168#ifndef _LIBCPP_NO_EXCEPTIONS
2169    try
2170    {
2171#endif // _LIBCPP_NO_EXCEPTIONS
2172    for (; __first != __last; ++__first)
2173        push_back(*__first);
2174#ifndef _LIBCPP_NO_EXCEPTIONS
2175    }
2176    catch (...)
2177    {
2178        if (__is_long())
2179            __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2180        throw;
2181    }
2182#endif // _LIBCPP_NO_EXCEPTIONS
2183}
2184
2185template <class _CharT, class _Traits, class _Allocator>
2186template <class _ForwardIterator>
2187__enable_if_t
2188<
2189    __is_cpp17_forward_iterator<_ForwardIterator>::value
2190>
2191basic_string<_CharT, _Traits, _Allocator>::__init(_ForwardIterator __first, _ForwardIterator __last)
2192{
2193    size_type __sz = static_cast<size_type>(_VSTD::distance(__first, __last));
2194    if (__sz > max_size())
2195        this->__throw_length_error();
2196    pointer __p;
2197    if (__sz < __min_cap)
2198    {
2199        __set_short_size(__sz);
2200        __p = __get_short_pointer();
2201    }
2202    else
2203    {
2204        size_type __cap = __recommend(__sz);
2205        __p = __alloc_traits::allocate(__alloc(), __cap+1);
2206        __set_long_pointer(__p);
2207        __set_long_cap(__cap+1);
2208        __set_long_size(__sz);
2209    }
2210
2211#ifndef _LIBCPP_NO_EXCEPTIONS
2212    try
2213    {
2214#endif  // _LIBCPP_NO_EXCEPTIONS
2215    for (; __first != __last; ++__first, (void) ++__p)
2216        traits_type::assign(*__p, *__first);
2217    traits_type::assign(*__p, value_type());
2218#ifndef _LIBCPP_NO_EXCEPTIONS
2219    }
2220    catch (...)
2221    {
2222        if (__is_long())
2223            __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2224        throw;
2225    }
2226#endif  // _LIBCPP_NO_EXCEPTIONS
2227}
2228
2229template <class _CharT, class _Traits, class _Allocator>
2230template<class _InputIterator, class>
2231inline
2232basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last)
2233     : __r_(__default_init_tag(), __default_init_tag())
2234{
2235    __init(__first, __last);
2236#if _LIBCPP_DEBUG_LEVEL == 2
2237    if (!__libcpp_is_constant_evaluated())
2238        __get_db()->__insert_c(this);
2239#endif
2240}
2241
2242template <class _CharT, class _Traits, class _Allocator>
2243template<class _InputIterator, class>
2244inline
2245basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last,
2246                                                        const allocator_type& __a)
2247    : __r_(__default_init_tag(), __a)
2248{
2249    __init(__first, __last);
2250#if _LIBCPP_DEBUG_LEVEL == 2
2251    if (!__libcpp_is_constant_evaluated())
2252        __get_db()->__insert_c(this);
2253#endif
2254}
2255
2256#ifndef _LIBCPP_CXX03_LANG
2257
2258template <class _CharT, class _Traits, class _Allocator>
2259inline
2260basic_string<_CharT, _Traits, _Allocator>::basic_string(
2261    initializer_list<_CharT> __il)
2262     : __r_(__default_init_tag(), __default_init_tag())
2263{
2264    __init(__il.begin(), __il.end());
2265#if _LIBCPP_DEBUG_LEVEL == 2
2266    if (!__libcpp_is_constant_evaluated())
2267        __get_db()->__insert_c(this);
2268#endif
2269}
2270
2271template <class _CharT, class _Traits, class _Allocator>
2272inline
2273
2274basic_string<_CharT, _Traits, _Allocator>::basic_string(
2275    initializer_list<_CharT> __il, const _Allocator& __a)
2276    : __r_(__default_init_tag(), __a)
2277{
2278    __init(__il.begin(), __il.end());
2279#if _LIBCPP_DEBUG_LEVEL == 2
2280    if (!__libcpp_is_constant_evaluated())
2281        __get_db()->__insert_c(this);
2282#endif
2283}
2284
2285#endif // _LIBCPP_CXX03_LANG
2286
2287template <class _CharT, class _Traits, class _Allocator>
2288basic_string<_CharT, _Traits, _Allocator>::~basic_string()
2289{
2290#if _LIBCPP_DEBUG_LEVEL == 2
2291    if (!__libcpp_is_constant_evaluated())
2292        __get_db()->__erase_c(this);
2293#endif
2294    if (__is_long())
2295        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2296}
2297
2298template <class _CharT, class _Traits, class _Allocator>
2299void
2300basic_string<_CharT, _Traits, _Allocator>::__grow_by_and_replace
2301    (size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2302     size_type __n_copy,  size_type __n_del,     size_type __n_add, const value_type* __p_new_stuff)
2303{
2304    size_type __ms = max_size();
2305    if (__delta_cap > __ms - __old_cap - 1)
2306        this->__throw_length_error();
2307    pointer __old_p = __get_pointer();
2308    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2309                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2310                          __ms - 1;
2311    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2312    __invalidate_all_iterators();
2313    if (__n_copy != 0)
2314        traits_type::copy(_VSTD::__to_address(__p),
2315                          _VSTD::__to_address(__old_p), __n_copy);
2316    if (__n_add != 0)
2317        traits_type::copy(_VSTD::__to_address(__p) + __n_copy, __p_new_stuff, __n_add);
2318    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2319    if (__sec_cp_sz != 0)
2320        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2321                          _VSTD::__to_address(__old_p) + __n_copy + __n_del, __sec_cp_sz);
2322    if (__old_cap+1 != __min_cap)
2323        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2324    __set_long_pointer(__p);
2325    __set_long_cap(__cap+1);
2326    __old_sz = __n_copy + __n_add + __sec_cp_sz;
2327    __set_long_size(__old_sz);
2328    traits_type::assign(__p[__old_sz], value_type());
2329}
2330
2331template <class _CharT, class _Traits, class _Allocator>
2332void
2333basic_string<_CharT, _Traits, _Allocator>::__grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2334                                                     size_type __n_copy,  size_type __n_del,     size_type __n_add)
2335{
2336    size_type __ms = max_size();
2337    if (__delta_cap > __ms - __old_cap)
2338        this->__throw_length_error();
2339    pointer __old_p = __get_pointer();
2340    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2341                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2342                          __ms - 1;
2343    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2344    __invalidate_all_iterators();
2345    if (__n_copy != 0)
2346        traits_type::copy(_VSTD::__to_address(__p),
2347                          _VSTD::__to_address(__old_p), __n_copy);
2348    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2349    if (__sec_cp_sz != 0)
2350        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2351                          _VSTD::__to_address(__old_p) + __n_copy + __n_del,
2352                          __sec_cp_sz);
2353    if (__old_cap+1 != __min_cap)
2354        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2355    __set_long_pointer(__p);
2356    __set_long_cap(__cap+1);
2357}
2358
2359// assign
2360
2361template <class _CharT, class _Traits, class _Allocator>
2362template <bool __is_short>
2363basic_string<_CharT, _Traits, _Allocator>&
2364basic_string<_CharT, _Traits, _Allocator>::__assign_no_alias(
2365    const value_type* __s, size_type __n) {
2366  size_type __cap = __is_short ? __min_cap : __get_long_cap();
2367  if (__n < __cap) {
2368    pointer __p = __is_short ? __get_short_pointer() : __get_long_pointer();
2369    __is_short ? __set_short_size(__n) : __set_long_size(__n);
2370    traits_type::copy(_VSTD::__to_address(__p), __s, __n);
2371    traits_type::assign(__p[__n], value_type());
2372    __invalidate_iterators_past(__n);
2373  } else {
2374    size_type __sz = __is_short ? __get_short_size() : __get_long_size();
2375    __grow_by_and_replace(__cap - 1, __n - __cap + 1, __sz, 0, __sz, __n, __s);
2376  }
2377  return *this;
2378}
2379
2380template <class _CharT, class _Traits, class _Allocator>
2381basic_string<_CharT, _Traits, _Allocator>&
2382basic_string<_CharT, _Traits, _Allocator>::__assign_external(
2383    const value_type* __s, size_type __n) {
2384  size_type __cap = capacity();
2385  if (__cap >= __n) {
2386    value_type* __p = _VSTD::__to_address(__get_pointer());
2387    traits_type::move(__p, __s, __n);
2388    return __null_terminate_at(__p, __n);
2389  } else {
2390    size_type __sz = size();
2391    __grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s);
2392    return *this;
2393  }
2394}
2395
2396template <class _CharT, class _Traits, class _Allocator>
2397basic_string<_CharT, _Traits, _Allocator>&
2398basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s, size_type __n)
2399{
2400    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::assign received nullptr");
2401    return (__builtin_constant_p(__n) && __n < __min_cap)
2402               ? __assign_short(__s, __n)
2403               : __assign_external(__s, __n);
2404}
2405
2406template <class _CharT, class _Traits, class _Allocator>
2407basic_string<_CharT, _Traits, _Allocator>&
2408basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
2409{
2410    size_type __cap = capacity();
2411    if (__cap < __n)
2412    {
2413        size_type __sz = size();
2414        __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2415    }
2416    value_type* __p = _VSTD::__to_address(__get_pointer());
2417    traits_type::assign(__p, __n, __c);
2418    return __null_terminate_at(__p, __n);
2419}
2420
2421template <class _CharT, class _Traits, class _Allocator>
2422basic_string<_CharT, _Traits, _Allocator>&
2423basic_string<_CharT, _Traits, _Allocator>::operator=(value_type __c)
2424{
2425    pointer __p;
2426    if (__is_long())
2427    {
2428        __p = __get_long_pointer();
2429        __set_long_size(1);
2430    }
2431    else
2432    {
2433        __p = __get_short_pointer();
2434        __set_short_size(1);
2435    }
2436    traits_type::assign(*__p, __c);
2437    traits_type::assign(*++__p, value_type());
2438    __invalidate_iterators_past(1);
2439    return *this;
2440}
2441
2442template <class _CharT, class _Traits, class _Allocator>
2443basic_string<_CharT, _Traits, _Allocator>&
2444basic_string<_CharT, _Traits, _Allocator>::operator=(const basic_string& __str)
2445{
2446  if (this != &__str) {
2447    __copy_assign_alloc(__str);
2448    if (!__is_long()) {
2449      if (!__str.__is_long()) {
2450        __r_.first().__r = __str.__r_.first().__r;
2451      } else {
2452        return __assign_no_alias<true>(__str.data(), __str.size());
2453      }
2454    } else {
2455      return __assign_no_alias<false>(__str.data(), __str.size());
2456    }
2457  }
2458  return *this;
2459}
2460
2461#ifndef _LIBCPP_CXX03_LANG
2462
2463template <class _CharT, class _Traits, class _Allocator>
2464inline
2465void
2466basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, false_type)
2467    _NOEXCEPT_(__alloc_traits::is_always_equal::value)
2468{
2469    if (__alloc() != __str.__alloc())
2470        assign(__str);
2471    else
2472        __move_assign(__str, true_type());
2473}
2474
2475template <class _CharT, class _Traits, class _Allocator>
2476inline
2477void
2478basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, true_type)
2479#if _LIBCPP_STD_VER > 14
2480    _NOEXCEPT
2481#else
2482    _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
2483#endif
2484{
2485  if (__is_long()) {
2486    __alloc_traits::deallocate(__alloc(), __get_long_pointer(),
2487                               __get_long_cap());
2488#if _LIBCPP_STD_VER <= 14
2489    if (!is_nothrow_move_assignable<allocator_type>::value) {
2490      __set_short_size(0);
2491      traits_type::assign(__get_short_pointer()[0], value_type());
2492    }
2493#endif
2494  }
2495  __move_assign_alloc(__str);
2496  __r_.first() = __str.__r_.first();
2497  __str.__set_short_size(0);
2498  traits_type::assign(__str.__get_short_pointer()[0], value_type());
2499}
2500
2501template <class _CharT, class _Traits, class _Allocator>
2502inline
2503basic_string<_CharT, _Traits, _Allocator>&
2504basic_string<_CharT, _Traits, _Allocator>::operator=(basic_string&& __str)
2505    _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
2506{
2507    __move_assign(__str, integral_constant<bool,
2508          __alloc_traits::propagate_on_container_move_assignment::value>());
2509    return *this;
2510}
2511
2512#endif
2513
2514template <class _CharT, class _Traits, class _Allocator>
2515template<class _InputIterator>
2516__enable_if_t
2517<
2518     __is_exactly_cpp17_input_iterator<_InputIterator>::value,
2519    basic_string<_CharT, _Traits, _Allocator>&
2520>
2521basic_string<_CharT, _Traits, _Allocator>::assign(_InputIterator __first, _InputIterator __last)
2522{
2523    const basic_string __temp(__first, __last, __alloc());
2524    assign(__temp.data(), __temp.size());
2525    return *this;
2526}
2527
2528template <class _CharT, class _Traits, class _Allocator>
2529template<class _ForwardIterator>
2530__enable_if_t
2531<
2532    __is_cpp17_forward_iterator<_ForwardIterator>::value,
2533    basic_string<_CharT, _Traits, _Allocator>&
2534>
2535basic_string<_CharT, _Traits, _Allocator>::assign(_ForwardIterator __first, _ForwardIterator __last)
2536{
2537    size_type __cap = capacity();
2538    size_type __n = __string_is_trivial_iterator<_ForwardIterator>::value ?
2539        static_cast<size_type>(_VSTD::distance(__first, __last)) : 0;
2540
2541    if (__string_is_trivial_iterator<_ForwardIterator>::value &&
2542        (__cap >= __n || !__addr_in_range(*__first)))
2543    {
2544        if (__cap < __n)
2545        {
2546            size_type __sz = size();
2547            __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2548        }
2549        pointer __p = __get_pointer();
2550        for (; __first != __last; ++__p, (void) ++__first)
2551            traits_type::assign(*__p, *__first);
2552        traits_type::assign(*__p, value_type());
2553        __set_size(__n);
2554        __invalidate_iterators_past(__n);
2555    }
2556    else
2557    {
2558        const basic_string __temp(__first, __last, __alloc());
2559        assign(__temp.data(), __temp.size());
2560    }
2561    return *this;
2562}
2563
2564template <class _CharT, class _Traits, class _Allocator>
2565basic_string<_CharT, _Traits, _Allocator>&
2566basic_string<_CharT, _Traits, _Allocator>::assign(const basic_string& __str, size_type __pos, size_type __n)
2567{
2568    size_type __sz = __str.size();
2569    if (__pos > __sz)
2570        this->__throw_out_of_range();
2571    return assign(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2572}
2573
2574template <class _CharT, class _Traits, class _Allocator>
2575template <class _Tp>
2576__enable_if_t
2577<
2578    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
2579    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2580    basic_string<_CharT, _Traits, _Allocator>&
2581>
2582basic_string<_CharT, _Traits, _Allocator>::assign(const _Tp & __t, size_type __pos, size_type __n)
2583{
2584    __self_view __sv = __t;
2585    size_type __sz = __sv.size();
2586    if (__pos > __sz)
2587        this->__throw_out_of_range();
2588    return assign(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2589}
2590
2591
2592template <class _CharT, class _Traits, class _Allocator>
2593basic_string<_CharT, _Traits, _Allocator>&
2594basic_string<_CharT, _Traits, _Allocator>::__assign_external(const value_type* __s) {
2595  return __assign_external(__s, traits_type::length(__s));
2596}
2597
2598template <class _CharT, class _Traits, class _Allocator>
2599basic_string<_CharT, _Traits, _Allocator>&
2600basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s)
2601{
2602    _LIBCPP_ASSERT(__s != nullptr, "string::assign received nullptr");
2603    return __builtin_constant_p(*__s)
2604               ? (traits_type::length(__s) < __min_cap
2605                      ? __assign_short(__s, traits_type::length(__s))
2606                      : __assign_external(__s, traits_type::length(__s)))
2607               : __assign_external(__s);
2608}
2609// append
2610
2611template <class _CharT, class _Traits, class _Allocator>
2612basic_string<_CharT, _Traits, _Allocator>&
2613basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s, size_type __n)
2614{
2615    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::append received nullptr");
2616    size_type __cap = capacity();
2617    size_type __sz = size();
2618    if (__cap - __sz >= __n)
2619    {
2620        if (__n)
2621        {
2622            value_type* __p = _VSTD::__to_address(__get_pointer());
2623            traits_type::copy(__p + __sz, __s, __n);
2624            __sz += __n;
2625            __set_size(__sz);
2626            traits_type::assign(__p[__sz], value_type());
2627        }
2628    }
2629    else
2630        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __sz, 0, __n, __s);
2631    return *this;
2632}
2633
2634template <class _CharT, class _Traits, class _Allocator>
2635basic_string<_CharT, _Traits, _Allocator>&
2636basic_string<_CharT, _Traits, _Allocator>::append(size_type __n, value_type __c)
2637{
2638    if (__n)
2639    {
2640        size_type __cap = capacity();
2641        size_type __sz = size();
2642        if (__cap - __sz < __n)
2643            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2644        pointer __p = __get_pointer();
2645        traits_type::assign(_VSTD::__to_address(__p) + __sz, __n, __c);
2646        __sz += __n;
2647        __set_size(__sz);
2648        traits_type::assign(__p[__sz], value_type());
2649    }
2650    return *this;
2651}
2652
2653template <class _CharT, class _Traits, class _Allocator>
2654inline void
2655basic_string<_CharT, _Traits, _Allocator>::__append_default_init(size_type __n)
2656{
2657    if (__n)
2658    {
2659        size_type __cap = capacity();
2660        size_type __sz = size();
2661        if (__cap - __sz < __n)
2662            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2663        pointer __p = __get_pointer();
2664        __sz += __n;
2665        __set_size(__sz);
2666        traits_type::assign(__p[__sz], value_type());
2667    }
2668}
2669
2670template <class _CharT, class _Traits, class _Allocator>
2671void
2672basic_string<_CharT, _Traits, _Allocator>::push_back(value_type __c)
2673{
2674    bool __is_short = !__is_long();
2675    size_type __cap;
2676    size_type __sz;
2677    if (__is_short)
2678    {
2679        __cap = __min_cap - 1;
2680        __sz = __get_short_size();
2681    }
2682    else
2683    {
2684        __cap = __get_long_cap() - 1;
2685        __sz = __get_long_size();
2686    }
2687    if (__sz == __cap)
2688    {
2689        __grow_by(__cap, 1, __sz, __sz, 0);
2690        __is_short = false; // the string is always long after __grow_by
2691    }
2692    pointer __p;
2693    if (__is_short)
2694    {
2695        __p = __get_short_pointer() + __sz;
2696        __set_short_size(__sz+1);
2697    }
2698    else
2699    {
2700        __p = __get_long_pointer() + __sz;
2701        __set_long_size(__sz+1);
2702    }
2703    traits_type::assign(*__p, __c);
2704    traits_type::assign(*++__p, value_type());
2705}
2706
2707template <class _CharT, class _Traits, class _Allocator>
2708template<class _ForwardIterator>
2709__enable_if_t
2710<
2711    __is_cpp17_forward_iterator<_ForwardIterator>::value,
2712    basic_string<_CharT, _Traits, _Allocator>&
2713>
2714basic_string<_CharT, _Traits, _Allocator>::append(
2715    _ForwardIterator __first, _ForwardIterator __last)
2716{
2717    size_type __sz = size();
2718    size_type __cap = capacity();
2719    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2720    if (__n)
2721    {
2722        if (__string_is_trivial_iterator<_ForwardIterator>::value &&
2723            !__addr_in_range(*__first))
2724        {
2725            if (__cap - __sz < __n)
2726                __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2727            pointer __p = __get_pointer() + __sz;
2728            for (; __first != __last; ++__p, (void) ++__first)
2729                traits_type::assign(*__p, *__first);
2730            traits_type::assign(*__p, value_type());
2731            __set_size(__sz + __n);
2732        }
2733        else
2734        {
2735            const basic_string __temp(__first, __last, __alloc());
2736            append(__temp.data(), __temp.size());
2737        }
2738    }
2739    return *this;
2740}
2741
2742template <class _CharT, class _Traits, class _Allocator>
2743inline
2744basic_string<_CharT, _Traits, _Allocator>&
2745basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str)
2746{
2747    return append(__str.data(), __str.size());
2748}
2749
2750template <class _CharT, class _Traits, class _Allocator>
2751basic_string<_CharT, _Traits, _Allocator>&
2752basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str, size_type __pos, size_type __n)
2753{
2754    size_type __sz = __str.size();
2755    if (__pos > __sz)
2756        this->__throw_out_of_range();
2757    return append(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2758}
2759
2760template <class _CharT, class _Traits, class _Allocator>
2761template <class _Tp>
2762    __enable_if_t
2763    <
2764        __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2765        basic_string<_CharT, _Traits, _Allocator>&
2766    >
2767basic_string<_CharT, _Traits, _Allocator>::append(const _Tp & __t, size_type __pos, size_type __n)
2768{
2769    __self_view __sv = __t;
2770    size_type __sz = __sv.size();
2771    if (__pos > __sz)
2772        this->__throw_out_of_range();
2773    return append(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2774}
2775
2776template <class _CharT, class _Traits, class _Allocator>
2777basic_string<_CharT, _Traits, _Allocator>&
2778basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s)
2779{
2780    _LIBCPP_ASSERT(__s != nullptr, "string::append received nullptr");
2781    return append(__s, traits_type::length(__s));
2782}
2783
2784// insert
2785
2786template <class _CharT, class _Traits, class _Allocator>
2787basic_string<_CharT, _Traits, _Allocator>&
2788basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s, size_type __n)
2789{
2790    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::insert received nullptr");
2791    size_type __sz = size();
2792    if (__pos > __sz)
2793        this->__throw_out_of_range();
2794    size_type __cap = capacity();
2795    if (__cap - __sz >= __n)
2796    {
2797        if (__n)
2798        {
2799            value_type* __p = _VSTD::__to_address(__get_pointer());
2800            size_type __n_move = __sz - __pos;
2801            if (__n_move != 0)
2802            {
2803                if (__p + __pos <= __s && __s < __p + __sz)
2804                    __s += __n;
2805                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2806            }
2807            traits_type::move(__p + __pos, __s, __n);
2808            __sz += __n;
2809            __set_size(__sz);
2810            traits_type::assign(__p[__sz], value_type());
2811        }
2812    }
2813    else
2814        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __pos, 0, __n, __s);
2815    return *this;
2816}
2817
2818template <class _CharT, class _Traits, class _Allocator>
2819basic_string<_CharT, _Traits, _Allocator>&
2820basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, size_type __n, value_type __c)
2821{
2822    size_type __sz = size();
2823    if (__pos > __sz)
2824        this->__throw_out_of_range();
2825    if (__n)
2826    {
2827        size_type __cap = capacity();
2828        value_type* __p;
2829        if (__cap - __sz >= __n)
2830        {
2831            __p = _VSTD::__to_address(__get_pointer());
2832            size_type __n_move = __sz - __pos;
2833            if (__n_move != 0)
2834                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2835        }
2836        else
2837        {
2838            __grow_by(__cap, __sz + __n - __cap, __sz, __pos, 0, __n);
2839            __p = _VSTD::__to_address(__get_long_pointer());
2840        }
2841        traits_type::assign(__p + __pos, __n, __c);
2842        __sz += __n;
2843        __set_size(__sz);
2844        traits_type::assign(__p[__sz], value_type());
2845    }
2846    return *this;
2847}
2848
2849template <class _CharT, class _Traits, class _Allocator>
2850template<class _InputIterator>
2851__enable_if_t
2852<
2853   __is_exactly_cpp17_input_iterator<_InputIterator>::value,
2854   typename basic_string<_CharT, _Traits, _Allocator>::iterator
2855>
2856basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _InputIterator __first, _InputIterator __last)
2857{
2858  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2859                       "string::insert(iterator, range) called with an iterator not"
2860                       " referring to this string");
2861  const basic_string __temp(__first, __last, __alloc());
2862  return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2863}
2864
2865template <class _CharT, class _Traits, class _Allocator>
2866template<class _ForwardIterator>
2867__enable_if_t
2868<
2869    __is_cpp17_forward_iterator<_ForwardIterator>::value,
2870    typename basic_string<_CharT, _Traits, _Allocator>::iterator
2871>
2872basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last)
2873{
2874  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2875                       "string::insert(iterator, range) called with an iterator not"
2876                       " referring to this string");
2877
2878    size_type __ip = static_cast<size_type>(__pos - begin());
2879    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2880    if (__n)
2881    {
2882        if (__string_is_trivial_iterator<_ForwardIterator>::value &&
2883            !__addr_in_range(*__first))
2884        {
2885            size_type __sz = size();
2886            size_type __cap = capacity();
2887            value_type* __p;
2888            if (__cap - __sz >= __n)
2889            {
2890                __p = _VSTD::__to_address(__get_pointer());
2891                size_type __n_move = __sz - __ip;
2892                if (__n_move != 0)
2893                    traits_type::move(__p + __ip + __n, __p + __ip, __n_move);
2894            }
2895            else
2896            {
2897                __grow_by(__cap, __sz + __n - __cap, __sz, __ip, 0, __n);
2898                __p = _VSTD::__to_address(__get_long_pointer());
2899            }
2900            __sz += __n;
2901            __set_size(__sz);
2902            traits_type::assign(__p[__sz], value_type());
2903            for (__p += __ip; __first != __last; ++__p, (void) ++__first)
2904                traits_type::assign(*__p, *__first);
2905        }
2906        else
2907        {
2908            const basic_string __temp(__first, __last, __alloc());
2909            return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2910        }
2911    }
2912    return begin() + __ip;
2913}
2914
2915template <class _CharT, class _Traits, class _Allocator>
2916inline
2917basic_string<_CharT, _Traits, _Allocator>&
2918basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str)
2919{
2920    return insert(__pos1, __str.data(), __str.size());
2921}
2922
2923template <class _CharT, class _Traits, class _Allocator>
2924basic_string<_CharT, _Traits, _Allocator>&
2925basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str,
2926                                                  size_type __pos2, size_type __n)
2927{
2928    size_type __str_sz = __str.size();
2929    if (__pos2 > __str_sz)
2930        this->__throw_out_of_range();
2931    return insert(__pos1, __str.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2932}
2933
2934template <class _CharT, class _Traits, class _Allocator>
2935template <class _Tp>
2936__enable_if_t
2937<
2938    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2939    basic_string<_CharT, _Traits, _Allocator>&
2940>
2941basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const _Tp& __t,
2942                                                  size_type __pos2, size_type __n)
2943{
2944    __self_view __sv = __t;
2945    size_type __str_sz = __sv.size();
2946    if (__pos2 > __str_sz)
2947        this->__throw_out_of_range();
2948    return insert(__pos1, __sv.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2949}
2950
2951template <class _CharT, class _Traits, class _Allocator>
2952basic_string<_CharT, _Traits, _Allocator>&
2953basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s)
2954{
2955    _LIBCPP_ASSERT(__s != nullptr, "string::insert received nullptr");
2956    return insert(__pos, __s, traits_type::length(__s));
2957}
2958
2959template <class _CharT, class _Traits, class _Allocator>
2960typename basic_string<_CharT, _Traits, _Allocator>::iterator
2961basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, value_type __c)
2962{
2963    size_type __ip = static_cast<size_type>(__pos - begin());
2964    size_type __sz = size();
2965    size_type __cap = capacity();
2966    value_type* __p;
2967    if (__cap == __sz)
2968    {
2969        __grow_by(__cap, 1, __sz, __ip, 0, 1);
2970        __p = _VSTD::__to_address(__get_long_pointer());
2971    }
2972    else
2973    {
2974        __p = _VSTD::__to_address(__get_pointer());
2975        size_type __n_move = __sz - __ip;
2976        if (__n_move != 0)
2977            traits_type::move(__p + __ip + 1, __p + __ip, __n_move);
2978    }
2979    traits_type::assign(__p[__ip], __c);
2980    traits_type::assign(__p[++__sz], value_type());
2981    __set_size(__sz);
2982    return begin() + static_cast<difference_type>(__ip);
2983}
2984
2985template <class _CharT, class _Traits, class _Allocator>
2986inline
2987typename basic_string<_CharT, _Traits, _Allocator>::iterator
2988basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, size_type __n, value_type __c)
2989{
2990  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2991                       "string::insert(iterator, n, value) called with an iterator not"
2992                       " referring to this string");
2993  difference_type __p = __pos - begin();
2994  insert(static_cast<size_type>(__p), __n, __c);
2995  return begin() + __p;
2996}
2997
2998// replace
2999
3000template <class _CharT, class _Traits, class _Allocator>
3001basic_string<_CharT, _Traits, _Allocator>&
3002basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2)
3003    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
3004{
3005    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::replace received nullptr");
3006    size_type __sz = size();
3007    if (__pos > __sz)
3008        this->__throw_out_of_range();
3009    __n1 = _VSTD::min(__n1, __sz - __pos);
3010    size_type __cap = capacity();
3011    if (__cap - __sz + __n1 >= __n2)
3012    {
3013        value_type* __p = _VSTD::__to_address(__get_pointer());
3014        if (__n1 != __n2)
3015        {
3016            size_type __n_move = __sz - __pos - __n1;
3017            if (__n_move != 0)
3018            {
3019                if (__n1 > __n2)
3020                {
3021                    traits_type::move(__p + __pos, __s, __n2);
3022                    traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
3023                    return __null_terminate_at(__p, __sz + (__n2 - __n1));
3024                }
3025                if (__p + __pos < __s && __s < __p + __sz)
3026                {
3027                    if (__p + __pos + __n1 <= __s)
3028                        __s += __n2 - __n1;
3029                    else // __p + __pos < __s < __p + __pos + __n1
3030                    {
3031                        traits_type::move(__p + __pos, __s, __n1);
3032                        __pos += __n1;
3033                        __s += __n2;
3034                        __n2 -= __n1;
3035                        __n1 = 0;
3036                    }
3037                }
3038                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
3039            }
3040        }
3041        traits_type::move(__p + __pos, __s, __n2);
3042        return __null_terminate_at(__p, __sz + (__n2 - __n1));
3043    }
3044    else
3045        __grow_by_and_replace(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2, __s);
3046    return *this;
3047}
3048
3049template <class _CharT, class _Traits, class _Allocator>
3050basic_string<_CharT, _Traits, _Allocator>&
3051basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, size_type __n2, value_type __c)
3052{
3053    size_type __sz = size();
3054    if (__pos > __sz)
3055        this->__throw_out_of_range();
3056    __n1 = _VSTD::min(__n1, __sz - __pos);
3057    size_type __cap = capacity();
3058    value_type* __p;
3059    if (__cap - __sz + __n1 >= __n2)
3060    {
3061        __p = _VSTD::__to_address(__get_pointer());
3062        if (__n1 != __n2)
3063        {
3064            size_type __n_move = __sz - __pos - __n1;
3065            if (__n_move != 0)
3066                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
3067        }
3068    }
3069    else
3070    {
3071        __grow_by(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2);
3072        __p = _VSTD::__to_address(__get_long_pointer());
3073    }
3074    traits_type::assign(__p + __pos, __n2, __c);
3075    return __null_terminate_at(__p, __sz - (__n1 - __n2));
3076}
3077
3078template <class _CharT, class _Traits, class _Allocator>
3079template<class _InputIterator>
3080__enable_if_t
3081<
3082    __is_cpp17_input_iterator<_InputIterator>::value,
3083    basic_string<_CharT, _Traits, _Allocator>&
3084>
3085basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2,
3086                                                   _InputIterator __j1, _InputIterator __j2)
3087{
3088    const basic_string __temp(__j1, __j2, __alloc());
3089    return this->replace(__i1, __i2, __temp);
3090}
3091
3092template <class _CharT, class _Traits, class _Allocator>
3093inline
3094basic_string<_CharT, _Traits, _Allocator>&
3095basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str)
3096{
3097    return replace(__pos1, __n1, __str.data(), __str.size());
3098}
3099
3100template <class _CharT, class _Traits, class _Allocator>
3101basic_string<_CharT, _Traits, _Allocator>&
3102basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str,
3103                                                   size_type __pos2, size_type __n2)
3104{
3105    size_type __str_sz = __str.size();
3106    if (__pos2 > __str_sz)
3107        this->__throw_out_of_range();
3108    return replace(__pos1, __n1, __str.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
3109}
3110
3111template <class _CharT, class _Traits, class _Allocator>
3112template <class _Tp>
3113__enable_if_t
3114<
3115    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
3116    basic_string<_CharT, _Traits, _Allocator>&
3117>
3118basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const _Tp& __t,
3119                                                   size_type __pos2, size_type __n2)
3120{
3121    __self_view __sv = __t;
3122    size_type __str_sz = __sv.size();
3123    if (__pos2 > __str_sz)
3124        this->__throw_out_of_range();
3125    return replace(__pos1, __n1, __sv.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
3126}
3127
3128template <class _CharT, class _Traits, class _Allocator>
3129basic_string<_CharT, _Traits, _Allocator>&
3130basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s)
3131{
3132    _LIBCPP_ASSERT(__s != nullptr, "string::replace received nullptr");
3133    return replace(__pos, __n1, __s, traits_type::length(__s));
3134}
3135
3136template <class _CharT, class _Traits, class _Allocator>
3137inline
3138basic_string<_CharT, _Traits, _Allocator>&
3139basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const basic_string& __str)
3140{
3141    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1),
3142                   __str.data(), __str.size());
3143}
3144
3145template <class _CharT, class _Traits, class _Allocator>
3146inline
3147basic_string<_CharT, _Traits, _Allocator>&
3148basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n)
3149{
3150    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s, __n);
3151}
3152
3153template <class _CharT, class _Traits, class _Allocator>
3154inline
3155basic_string<_CharT, _Traits, _Allocator>&
3156basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s)
3157{
3158    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s);
3159}
3160
3161template <class _CharT, class _Traits, class _Allocator>
3162inline
3163basic_string<_CharT, _Traits, _Allocator>&
3164basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c)
3165{
3166    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __n, __c);
3167}
3168
3169// erase
3170
3171// 'externally instantiated' erase() implementation, called when __n != npos.
3172// Does not check __pos against size()
3173template <class _CharT, class _Traits, class _Allocator>
3174void
3175basic_string<_CharT, _Traits, _Allocator>::__erase_external_with_move(
3176    size_type __pos, size_type __n)
3177{
3178    if (__n)
3179    {
3180        size_type __sz = size();
3181        value_type* __p = _VSTD::__to_address(__get_pointer());
3182        __n = _VSTD::min(__n, __sz - __pos);
3183        size_type __n_move = __sz - __pos - __n;
3184        if (__n_move != 0)
3185            traits_type::move(__p + __pos, __p + __pos + __n, __n_move);
3186        __null_terminate_at(__p, __sz - __n);
3187    }
3188}
3189
3190template <class _CharT, class _Traits, class _Allocator>
3191basic_string<_CharT, _Traits, _Allocator>&
3192basic_string<_CharT, _Traits, _Allocator>::erase(size_type __pos,
3193                                                 size_type __n) {
3194  if (__pos > size()) this->__throw_out_of_range();
3195  if (__n == npos) {
3196    __erase_to_end(__pos);
3197  } else {
3198    __erase_external_with_move(__pos, __n);
3199  }
3200  return *this;
3201}
3202
3203template <class _CharT, class _Traits, class _Allocator>
3204inline
3205typename basic_string<_CharT, _Traits, _Allocator>::iterator
3206basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __pos)
3207{
3208  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
3209                       "string::erase(iterator) called with an iterator not"
3210                       " referring to this string");
3211
3212  _LIBCPP_ASSERT(__pos != end(), "string::erase(iterator) called with a non-dereferenceable iterator");
3213  iterator __b = begin();
3214  size_type __r = static_cast<size_type>(__pos - __b);
3215  erase(__r, 1);
3216  return __b + static_cast<difference_type>(__r);
3217}
3218
3219template <class _CharT, class _Traits, class _Allocator>
3220inline
3221typename basic_string<_CharT, _Traits, _Allocator>::iterator
3222basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __first, const_iterator __last)
3223{
3224  _LIBCPP_DEBUG_ASSERT(__get_const_db()->__find_c_from_i(&__first) == this,
3225                       "string::erase(iterator,  iterator) called with an iterator not"
3226                       " referring to this string");
3227
3228  _LIBCPP_ASSERT(__first <= __last, "string::erase(first, last) called with invalid range");
3229  iterator __b = begin();
3230  size_type __r = static_cast<size_type>(__first - __b);
3231  erase(__r, static_cast<size_type>(__last - __first));
3232  return __b + static_cast<difference_type>(__r);
3233}
3234
3235template <class _CharT, class _Traits, class _Allocator>
3236inline
3237void
3238basic_string<_CharT, _Traits, _Allocator>::pop_back()
3239{
3240    _LIBCPP_ASSERT(!empty(), "string::pop_back(): string is already empty");
3241    __erase_to_end(size() - 1);
3242}
3243
3244template <class _CharT, class _Traits, class _Allocator>
3245inline
3246void
3247basic_string<_CharT, _Traits, _Allocator>::clear() _NOEXCEPT
3248{
3249    __invalidate_all_iterators();
3250    if (__is_long())
3251    {
3252        traits_type::assign(*__get_long_pointer(), value_type());
3253        __set_long_size(0);
3254    }
3255    else
3256    {
3257        traits_type::assign(*__get_short_pointer(), value_type());
3258        __set_short_size(0);
3259    }
3260}
3261
3262template <class _CharT, class _Traits, class _Allocator>
3263inline
3264void
3265basic_string<_CharT, _Traits, _Allocator>::__erase_to_end(size_type __pos)
3266{
3267  __null_terminate_at(_VSTD::__to_address(__get_pointer()), __pos);
3268}
3269
3270template <class _CharT, class _Traits, class _Allocator>
3271void
3272basic_string<_CharT, _Traits, _Allocator>::resize(size_type __n, value_type __c)
3273{
3274    size_type __sz = size();
3275    if (__n > __sz)
3276        append(__n - __sz, __c);
3277    else
3278        __erase_to_end(__n);
3279}
3280
3281template <class _CharT, class _Traits, class _Allocator>
3282inline void
3283basic_string<_CharT, _Traits, _Allocator>::__resize_default_init(size_type __n)
3284{
3285    size_type __sz = size();
3286    if (__n > __sz) {
3287       __append_default_init(__n - __sz);
3288    } else
3289        __erase_to_end(__n);
3290}
3291
3292template <class _CharT, class _Traits, class _Allocator>
3293inline
3294typename basic_string<_CharT, _Traits, _Allocator>::size_type
3295basic_string<_CharT, _Traits, _Allocator>::max_size() const _NOEXCEPT
3296{
3297    size_type __m = __alloc_traits::max_size(__alloc());
3298#ifdef _LIBCPP_BIG_ENDIAN
3299    return (__m <= ~__long_mask ? __m : __m/2) - __alignment;
3300#else
3301    return __m - __alignment;
3302#endif
3303}
3304
3305template <class _CharT, class _Traits, class _Allocator>
3306void
3307basic_string<_CharT, _Traits, _Allocator>::reserve(size_type __requested_capacity)
3308{
3309    if (__requested_capacity > max_size())
3310        this->__throw_length_error();
3311
3312#if _LIBCPP_STD_VER > 17
3313    // Reserve never shrinks as of C++20.
3314    if (__requested_capacity <= capacity()) return;
3315#endif
3316
3317    size_type __target_capacity = _VSTD::max(__requested_capacity, size());
3318    __target_capacity = __recommend(__target_capacity);
3319    if (__target_capacity == capacity()) return;
3320
3321    __shrink_or_extend(__target_capacity);
3322}
3323
3324template <class _CharT, class _Traits, class _Allocator>
3325inline
3326void
3327basic_string<_CharT, _Traits, _Allocator>::shrink_to_fit() _NOEXCEPT
3328{
3329    size_type __target_capacity = __recommend(size());
3330    if (__target_capacity == capacity()) return;
3331
3332    __shrink_or_extend(__target_capacity);
3333}
3334
3335template <class _CharT, class _Traits, class _Allocator>
3336inline
3337void
3338basic_string<_CharT, _Traits, _Allocator>::__shrink_or_extend(size_type __target_capacity)
3339{
3340    size_type __cap = capacity();
3341    size_type __sz = size();
3342
3343    pointer __new_data, __p;
3344    bool __was_long, __now_long;
3345    if (__target_capacity == __min_cap - 1)
3346    {
3347        __was_long = true;
3348        __now_long = false;
3349        __new_data = __get_short_pointer();
3350        __p = __get_long_pointer();
3351    }
3352    else
3353    {
3354        if (__target_capacity > __cap)
3355            __new_data = __alloc_traits::allocate(__alloc(), __target_capacity+1);
3356        else
3357        {
3358        #ifndef _LIBCPP_NO_EXCEPTIONS
3359            try
3360            {
3361        #endif // _LIBCPP_NO_EXCEPTIONS
3362                __new_data = __alloc_traits::allocate(__alloc(), __target_capacity+1);
3363        #ifndef _LIBCPP_NO_EXCEPTIONS
3364            }
3365            catch (...)
3366            {
3367                return;
3368            }
3369        #else  // _LIBCPP_NO_EXCEPTIONS
3370            if (__new_data == nullptr)
3371                return;
3372        #endif // _LIBCPP_NO_EXCEPTIONS
3373        }
3374        __now_long = true;
3375        __was_long = __is_long();
3376        __p = __get_pointer();
3377    }
3378    traits_type::copy(_VSTD::__to_address(__new_data),
3379                        _VSTD::__to_address(__p), size()+1);
3380    if (__was_long)
3381        __alloc_traits::deallocate(__alloc(), __p, __cap+1);
3382    if (__now_long)
3383    {
3384        __set_long_cap(__target_capacity+1);
3385        __set_long_size(__sz);
3386        __set_long_pointer(__new_data);
3387    }
3388    else
3389        __set_short_size(__sz);
3390    __invalidate_all_iterators();
3391}
3392
3393template <class _CharT, class _Traits, class _Allocator>
3394inline
3395typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3396basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) const _NOEXCEPT
3397{
3398    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3399    return *(data() + __pos);
3400}
3401
3402template <class _CharT, class _Traits, class _Allocator>
3403inline
3404typename basic_string<_CharT, _Traits, _Allocator>::reference
3405basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) _NOEXCEPT
3406{
3407    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3408    return *(__get_pointer() + __pos);
3409}
3410
3411template <class _CharT, class _Traits, class _Allocator>
3412typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3413basic_string<_CharT, _Traits, _Allocator>::at(size_type __n) const
3414{
3415    if (__n >= size())
3416        this->__throw_out_of_range();
3417    return (*this)[__n];
3418}
3419
3420template <class _CharT, class _Traits, class _Allocator>
3421typename basic_string<_CharT, _Traits, _Allocator>::reference
3422basic_string<_CharT, _Traits, _Allocator>::at(size_type __n)
3423{
3424    if (__n >= size())
3425        this->__throw_out_of_range();
3426    return (*this)[__n];
3427}
3428
3429template <class _CharT, class _Traits, class _Allocator>
3430inline
3431typename basic_string<_CharT, _Traits, _Allocator>::reference
3432basic_string<_CharT, _Traits, _Allocator>::front() _NOEXCEPT
3433{
3434    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3435    return *__get_pointer();
3436}
3437
3438template <class _CharT, class _Traits, class _Allocator>
3439inline
3440typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3441basic_string<_CharT, _Traits, _Allocator>::front() const _NOEXCEPT
3442{
3443    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3444    return *data();
3445}
3446
3447template <class _CharT, class _Traits, class _Allocator>
3448inline
3449typename basic_string<_CharT, _Traits, _Allocator>::reference
3450basic_string<_CharT, _Traits, _Allocator>::back() _NOEXCEPT
3451{
3452    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3453    return *(__get_pointer() + size() - 1);
3454}
3455
3456template <class _CharT, class _Traits, class _Allocator>
3457inline
3458typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3459basic_string<_CharT, _Traits, _Allocator>::back() const _NOEXCEPT
3460{
3461    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3462    return *(data() + size() - 1);
3463}
3464
3465template <class _CharT, class _Traits, class _Allocator>
3466typename basic_string<_CharT, _Traits, _Allocator>::size_type
3467basic_string<_CharT, _Traits, _Allocator>::copy(value_type* __s, size_type __n, size_type __pos) const
3468{
3469    size_type __sz = size();
3470    if (__pos > __sz)
3471        this->__throw_out_of_range();
3472    size_type __rlen = _VSTD::min(__n, __sz - __pos);
3473    traits_type::copy(__s, data() + __pos, __rlen);
3474    return __rlen;
3475}
3476
3477template <class _CharT, class _Traits, class _Allocator>
3478inline
3479basic_string<_CharT, _Traits, _Allocator>
3480basic_string<_CharT, _Traits, _Allocator>::substr(size_type __pos, size_type __n) const
3481{
3482    return basic_string(*this, __pos, __n, __alloc());
3483}
3484
3485template <class _CharT, class _Traits, class _Allocator>
3486inline
3487void
3488basic_string<_CharT, _Traits, _Allocator>::swap(basic_string& __str)
3489#if _LIBCPP_STD_VER >= 14
3490        _NOEXCEPT
3491#else
3492        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
3493                    __is_nothrow_swappable<allocator_type>::value)
3494#endif
3495{
3496#if _LIBCPP_DEBUG_LEVEL == 2
3497    if (!__libcpp_is_constant_evaluated()) {
3498        if (!__is_long())
3499            __get_db()->__invalidate_all(this);
3500        if (!__str.__is_long())
3501            __get_db()->__invalidate_all(&__str);
3502        __get_db()->swap(this, &__str);
3503    }
3504#endif
3505    _LIBCPP_ASSERT(
3506        __alloc_traits::propagate_on_container_swap::value ||
3507        __alloc_traits::is_always_equal::value ||
3508        __alloc() == __str.__alloc(), "swapping non-equal allocators");
3509    _VSTD::swap(__r_.first(), __str.__r_.first());
3510    _VSTD::__swap_allocator(__alloc(), __str.__alloc());
3511}
3512
3513// find
3514
3515template <class _Traits>
3516struct _LIBCPP_HIDDEN __traits_eq
3517{
3518    typedef typename _Traits::char_type char_type;
3519    _LIBCPP_INLINE_VISIBILITY
3520    bool operator()(const char_type& __x, const char_type& __y) _NOEXCEPT
3521        {return _Traits::eq(__x, __y);}
3522};
3523
3524template<class _CharT, class _Traits, class _Allocator>
3525typename basic_string<_CharT, _Traits, _Allocator>::size_type
3526basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3527                                                size_type __pos,
3528                                                size_type __n) const _NOEXCEPT
3529{
3530    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find(): received nullptr");
3531    return __str_find<value_type, size_type, traits_type, npos>
3532        (data(), size(), __s, __pos, __n);
3533}
3534
3535template<class _CharT, class _Traits, class _Allocator>
3536inline
3537typename basic_string<_CharT, _Traits, _Allocator>::size_type
3538basic_string<_CharT, _Traits, _Allocator>::find(const basic_string& __str,
3539                                                size_type __pos) const _NOEXCEPT
3540{
3541    return __str_find<value_type, size_type, traits_type, npos>
3542        (data(), size(), __str.data(), __pos, __str.size());
3543}
3544
3545template<class _CharT, class _Traits, class _Allocator>
3546template <class _Tp>
3547__enable_if_t
3548<
3549    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3550    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3551>
3552basic_string<_CharT, _Traits, _Allocator>::find(const _Tp &__t,
3553                                                size_type __pos) const _NOEXCEPT
3554{
3555    __self_view __sv = __t;
3556    return __str_find<value_type, size_type, traits_type, npos>
3557        (data(), size(), __sv.data(), __pos, __sv.size());
3558}
3559
3560template<class _CharT, class _Traits, class _Allocator>
3561inline
3562typename basic_string<_CharT, _Traits, _Allocator>::size_type
3563basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3564                                                size_type __pos) const _NOEXCEPT
3565{
3566    _LIBCPP_ASSERT(__s != nullptr, "string::find(): received nullptr");
3567    return __str_find<value_type, size_type, traits_type, npos>
3568        (data(), size(), __s, __pos, traits_type::length(__s));
3569}
3570
3571template<class _CharT, class _Traits, class _Allocator>
3572typename basic_string<_CharT, _Traits, _Allocator>::size_type
3573basic_string<_CharT, _Traits, _Allocator>::find(value_type __c,
3574                                                size_type __pos) const _NOEXCEPT
3575{
3576    return __str_find<value_type, size_type, traits_type, npos>
3577        (data(), size(), __c, __pos);
3578}
3579
3580// rfind
3581
3582template<class _CharT, class _Traits, class _Allocator>
3583typename basic_string<_CharT, _Traits, _Allocator>::size_type
3584basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3585                                                 size_type __pos,
3586                                                 size_type __n) const _NOEXCEPT
3587{
3588    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::rfind(): received nullptr");
3589    return __str_rfind<value_type, size_type, traits_type, npos>
3590        (data(), size(), __s, __pos, __n);
3591}
3592
3593template<class _CharT, class _Traits, class _Allocator>
3594inline
3595typename basic_string<_CharT, _Traits, _Allocator>::size_type
3596basic_string<_CharT, _Traits, _Allocator>::rfind(const basic_string& __str,
3597                                                 size_type __pos) const _NOEXCEPT
3598{
3599    return __str_rfind<value_type, size_type, traits_type, npos>
3600        (data(), size(), __str.data(), __pos, __str.size());
3601}
3602
3603template<class _CharT, class _Traits, class _Allocator>
3604template <class _Tp>
3605__enable_if_t
3606<
3607    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3608    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3609>
3610basic_string<_CharT, _Traits, _Allocator>::rfind(const _Tp& __t,
3611                                                size_type __pos) const _NOEXCEPT
3612{
3613    __self_view __sv = __t;
3614    return __str_rfind<value_type, size_type, traits_type, npos>
3615        (data(), size(), __sv.data(), __pos, __sv.size());
3616}
3617
3618template<class _CharT, class _Traits, class _Allocator>
3619inline
3620typename basic_string<_CharT, _Traits, _Allocator>::size_type
3621basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3622                                                 size_type __pos) const _NOEXCEPT
3623{
3624    _LIBCPP_ASSERT(__s != nullptr, "string::rfind(): received nullptr");
3625    return __str_rfind<value_type, size_type, traits_type, npos>
3626        (data(), size(), __s, __pos, traits_type::length(__s));
3627}
3628
3629template<class _CharT, class _Traits, class _Allocator>
3630typename basic_string<_CharT, _Traits, _Allocator>::size_type
3631basic_string<_CharT, _Traits, _Allocator>::rfind(value_type __c,
3632                                                 size_type __pos) const _NOEXCEPT
3633{
3634    return __str_rfind<value_type, size_type, traits_type, npos>
3635        (data(), size(), __c, __pos);
3636}
3637
3638// find_first_of
3639
3640template<class _CharT, class _Traits, class _Allocator>
3641typename basic_string<_CharT, _Traits, _Allocator>::size_type
3642basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3643                                                         size_type __pos,
3644                                                         size_type __n) const _NOEXCEPT
3645{
3646    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_of(): received nullptr");
3647    return __str_find_first_of<value_type, size_type, traits_type, npos>
3648        (data(), size(), __s, __pos, __n);
3649}
3650
3651template<class _CharT, class _Traits, class _Allocator>
3652inline
3653typename basic_string<_CharT, _Traits, _Allocator>::size_type
3654basic_string<_CharT, _Traits, _Allocator>::find_first_of(const basic_string& __str,
3655                                                         size_type __pos) const _NOEXCEPT
3656{
3657    return __str_find_first_of<value_type, size_type, traits_type, npos>
3658        (data(), size(), __str.data(), __pos, __str.size());
3659}
3660
3661template<class _CharT, class _Traits, class _Allocator>
3662template <class _Tp>
3663__enable_if_t
3664<
3665    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3666    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3667>
3668basic_string<_CharT, _Traits, _Allocator>::find_first_of(const _Tp& __t,
3669                                                size_type __pos) const _NOEXCEPT
3670{
3671    __self_view __sv = __t;
3672    return __str_find_first_of<value_type, size_type, traits_type, npos>
3673        (data(), size(), __sv.data(), __pos, __sv.size());
3674}
3675
3676template<class _CharT, class _Traits, class _Allocator>
3677inline
3678typename basic_string<_CharT, _Traits, _Allocator>::size_type
3679basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3680                                                         size_type __pos) const _NOEXCEPT
3681{
3682    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_of(): received nullptr");
3683    return __str_find_first_of<value_type, size_type, traits_type, npos>
3684        (data(), size(), __s, __pos, traits_type::length(__s));
3685}
3686
3687template<class _CharT, class _Traits, class _Allocator>
3688inline
3689typename basic_string<_CharT, _Traits, _Allocator>::size_type
3690basic_string<_CharT, _Traits, _Allocator>::find_first_of(value_type __c,
3691                                                         size_type __pos) const _NOEXCEPT
3692{
3693    return find(__c, __pos);
3694}
3695
3696// find_last_of
3697
3698template<class _CharT, class _Traits, class _Allocator>
3699typename basic_string<_CharT, _Traits, _Allocator>::size_type
3700basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3701                                                        size_type __pos,
3702                                                        size_type __n) const _NOEXCEPT
3703{
3704    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_of(): received nullptr");
3705    return __str_find_last_of<value_type, size_type, traits_type, npos>
3706        (data(), size(), __s, __pos, __n);
3707}
3708
3709template<class _CharT, class _Traits, class _Allocator>
3710inline
3711typename basic_string<_CharT, _Traits, _Allocator>::size_type
3712basic_string<_CharT, _Traits, _Allocator>::find_last_of(const basic_string& __str,
3713                                                        size_type __pos) const _NOEXCEPT
3714{
3715    return __str_find_last_of<value_type, size_type, traits_type, npos>
3716        (data(), size(), __str.data(), __pos, __str.size());
3717}
3718
3719template<class _CharT, class _Traits, class _Allocator>
3720template <class _Tp>
3721__enable_if_t
3722<
3723    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3724    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3725>
3726basic_string<_CharT, _Traits, _Allocator>::find_last_of(const _Tp& __t,
3727                                                size_type __pos) const _NOEXCEPT
3728{
3729    __self_view __sv = __t;
3730    return __str_find_last_of<value_type, size_type, traits_type, npos>
3731        (data(), size(), __sv.data(), __pos, __sv.size());
3732}
3733
3734template<class _CharT, class _Traits, class _Allocator>
3735inline
3736typename basic_string<_CharT, _Traits, _Allocator>::size_type
3737basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3738                                                        size_type __pos) const _NOEXCEPT
3739{
3740    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_of(): received nullptr");
3741    return __str_find_last_of<value_type, size_type, traits_type, npos>
3742        (data(), size(), __s, __pos, traits_type::length(__s));
3743}
3744
3745template<class _CharT, class _Traits, class _Allocator>
3746inline
3747typename basic_string<_CharT, _Traits, _Allocator>::size_type
3748basic_string<_CharT, _Traits, _Allocator>::find_last_of(value_type __c,
3749                                                        size_type __pos) const _NOEXCEPT
3750{
3751    return rfind(__c, __pos);
3752}
3753
3754// find_first_not_of
3755
3756template<class _CharT, class _Traits, class _Allocator>
3757typename basic_string<_CharT, _Traits, _Allocator>::size_type
3758basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3759                                                             size_type __pos,
3760                                                             size_type __n) const _NOEXCEPT
3761{
3762    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_not_of(): received nullptr");
3763    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3764        (data(), size(), __s, __pos, __n);
3765}
3766
3767template<class _CharT, class _Traits, class _Allocator>
3768inline
3769typename basic_string<_CharT, _Traits, _Allocator>::size_type
3770basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const basic_string& __str,
3771                                                             size_type __pos) const _NOEXCEPT
3772{
3773    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3774        (data(), size(), __str.data(), __pos, __str.size());
3775}
3776
3777template<class _CharT, class _Traits, class _Allocator>
3778template <class _Tp>
3779__enable_if_t
3780<
3781    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3782    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3783>
3784basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const _Tp& __t,
3785                                                size_type __pos) const _NOEXCEPT
3786{
3787    __self_view __sv = __t;
3788    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3789        (data(), size(), __sv.data(), __pos, __sv.size());
3790}
3791
3792template<class _CharT, class _Traits, class _Allocator>
3793inline
3794typename basic_string<_CharT, _Traits, _Allocator>::size_type
3795basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3796                                                             size_type __pos) const _NOEXCEPT
3797{
3798    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_not_of(): received nullptr");
3799    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3800        (data(), size(), __s, __pos, traits_type::length(__s));
3801}
3802
3803template<class _CharT, class _Traits, class _Allocator>
3804inline
3805typename basic_string<_CharT, _Traits, _Allocator>::size_type
3806basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(value_type __c,
3807                                                             size_type __pos) const _NOEXCEPT
3808{
3809    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3810        (data(), size(), __c, __pos);
3811}
3812
3813// find_last_not_of
3814
3815template<class _CharT, class _Traits, class _Allocator>
3816typename basic_string<_CharT, _Traits, _Allocator>::size_type
3817basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3818                                                            size_type __pos,
3819                                                            size_type __n) const _NOEXCEPT
3820{
3821    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_not_of(): received nullptr");
3822    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3823        (data(), size(), __s, __pos, __n);
3824}
3825
3826template<class _CharT, class _Traits, class _Allocator>
3827inline
3828typename basic_string<_CharT, _Traits, _Allocator>::size_type
3829basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const basic_string& __str,
3830                                                            size_type __pos) const _NOEXCEPT
3831{
3832    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3833        (data(), size(), __str.data(), __pos, __str.size());
3834}
3835
3836template<class _CharT, class _Traits, class _Allocator>
3837template <class _Tp>
3838__enable_if_t
3839<
3840    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3841    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3842>
3843basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const _Tp& __t,
3844                                                size_type __pos) const _NOEXCEPT
3845{
3846    __self_view __sv = __t;
3847    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3848        (data(), size(), __sv.data(), __pos, __sv.size());
3849}
3850
3851template<class _CharT, class _Traits, class _Allocator>
3852inline
3853typename basic_string<_CharT, _Traits, _Allocator>::size_type
3854basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3855                                                            size_type __pos) const _NOEXCEPT
3856{
3857    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_not_of(): received nullptr");
3858    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3859        (data(), size(), __s, __pos, traits_type::length(__s));
3860}
3861
3862template<class _CharT, class _Traits, class _Allocator>
3863inline
3864typename basic_string<_CharT, _Traits, _Allocator>::size_type
3865basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(value_type __c,
3866                                                            size_type __pos) const _NOEXCEPT
3867{
3868    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3869        (data(), size(), __c, __pos);
3870}
3871
3872// compare
3873
3874template <class _CharT, class _Traits, class _Allocator>
3875template <class _Tp>
3876__enable_if_t
3877<
3878    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3879    int
3880>
3881basic_string<_CharT, _Traits, _Allocator>::compare(const _Tp& __t) const _NOEXCEPT
3882{
3883    __self_view __sv = __t;
3884    size_t __lhs_sz = size();
3885    size_t __rhs_sz = __sv.size();
3886    int __result = traits_type::compare(data(), __sv.data(),
3887                                        _VSTD::min(__lhs_sz, __rhs_sz));
3888    if (__result != 0)
3889        return __result;
3890    if (__lhs_sz < __rhs_sz)
3891        return -1;
3892    if (__lhs_sz > __rhs_sz)
3893        return 1;
3894    return 0;
3895}
3896
3897template <class _CharT, class _Traits, class _Allocator>
3898inline
3899int
3900basic_string<_CharT, _Traits, _Allocator>::compare(const basic_string& __str) const _NOEXCEPT
3901{
3902    return compare(__self_view(__str));
3903}
3904
3905template <class _CharT, class _Traits, class _Allocator>
3906int
3907basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3908                                                   size_type __n1,
3909                                                   const value_type* __s,
3910                                                   size_type __n2) const
3911{
3912    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::compare(): received nullptr");
3913    size_type __sz = size();
3914    if (__pos1 > __sz || __n2 == npos)
3915        this->__throw_out_of_range();
3916    size_type __rlen = _VSTD::min(__n1, __sz - __pos1);
3917    int __r = traits_type::compare(data() + __pos1, __s, _VSTD::min(__rlen, __n2));
3918    if (__r == 0)
3919    {
3920        if (__rlen < __n2)
3921            __r = -1;
3922        else if (__rlen > __n2)
3923            __r = 1;
3924    }
3925    return __r;
3926}
3927
3928template <class _CharT, class _Traits, class _Allocator>
3929template <class _Tp>
3930__enable_if_t
3931<
3932    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3933    int
3934>
3935basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3936                                                   size_type __n1,
3937                                                   const _Tp& __t) const
3938{
3939    __self_view __sv = __t;
3940    return compare(__pos1, __n1, __sv.data(), __sv.size());
3941}
3942
3943template <class _CharT, class _Traits, class _Allocator>
3944inline
3945int
3946basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3947                                                   size_type __n1,
3948                                                   const basic_string& __str) const
3949{
3950    return compare(__pos1, __n1, __str.data(), __str.size());
3951}
3952
3953template <class _CharT, class _Traits, class _Allocator>
3954template <class _Tp>
3955__enable_if_t
3956<
3957    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
3958    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
3959    int
3960>
3961basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3962                                                   size_type __n1,
3963                                                   const _Tp& __t,
3964                                                   size_type __pos2,
3965                                                   size_type __n2) const
3966{
3967    __self_view __sv = __t;
3968    return __self_view(*this).substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
3969}
3970
3971template <class _CharT, class _Traits, class _Allocator>
3972int
3973basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3974                                                   size_type __n1,
3975                                                   const basic_string& __str,
3976                                                   size_type __pos2,
3977                                                   size_type __n2) const
3978{
3979        return compare(__pos1, __n1, __self_view(__str), __pos2, __n2);
3980}
3981
3982template <class _CharT, class _Traits, class _Allocator>
3983int
3984basic_string<_CharT, _Traits, _Allocator>::compare(const value_type* __s) const _NOEXCEPT
3985{
3986    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3987    return compare(0, npos, __s, traits_type::length(__s));
3988}
3989
3990template <class _CharT, class _Traits, class _Allocator>
3991int
3992basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3993                                                   size_type __n1,
3994                                                   const value_type* __s) const
3995{
3996    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3997    return compare(__pos1, __n1, __s, traits_type::length(__s));
3998}
3999
4000// __invariants
4001
4002template<class _CharT, class _Traits, class _Allocator>
4003inline
4004bool
4005basic_string<_CharT, _Traits, _Allocator>::__invariants() const
4006{
4007    if (size() > capacity())
4008        return false;
4009    if (capacity() < __min_cap - 1)
4010        return false;
4011    if (data() == nullptr)
4012        return false;
4013    if (data()[size()] != value_type())
4014        return false;
4015    return true;
4016}
4017
4018// __clear_and_shrink
4019
4020template<class _CharT, class _Traits, class _Allocator>
4021inline
4022void
4023basic_string<_CharT, _Traits, _Allocator>::__clear_and_shrink() _NOEXCEPT
4024{
4025    clear();
4026    if(__is_long())
4027    {
4028        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), capacity() + 1);
4029        __set_long_cap(0);
4030        __set_short_size(0);
4031        traits_type::assign(*__get_short_pointer(), value_type());
4032    }
4033}
4034
4035// operator==
4036
4037template<class _CharT, class _Traits, class _Allocator>
4038inline _LIBCPP_INLINE_VISIBILITY
4039bool
4040operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4041           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4042{
4043    size_t __lhs_sz = __lhs.size();
4044    return __lhs_sz == __rhs.size() && _Traits::compare(__lhs.data(),
4045                                                        __rhs.data(),
4046                                                        __lhs_sz) == 0;
4047}
4048
4049template<class _Allocator>
4050inline _LIBCPP_INLINE_VISIBILITY
4051bool
4052operator==(const basic_string<char, char_traits<char>, _Allocator>& __lhs,
4053           const basic_string<char, char_traits<char>, _Allocator>& __rhs) _NOEXCEPT
4054{
4055    size_t __lhs_sz = __lhs.size();
4056    if (__lhs_sz != __rhs.size())
4057        return false;
4058    const char* __lp = __lhs.data();
4059    const char* __rp = __rhs.data();
4060    if (__lhs.__is_long())
4061        return char_traits<char>::compare(__lp, __rp, __lhs_sz) == 0;
4062    for (; __lhs_sz != 0; --__lhs_sz, ++__lp, ++__rp)
4063        if (*__lp != *__rp)
4064            return false;
4065    return true;
4066}
4067
4068template<class _CharT, class _Traits, class _Allocator>
4069inline _LIBCPP_INLINE_VISIBILITY
4070bool
4071operator==(const _CharT* __lhs,
4072           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4073{
4074    typedef basic_string<_CharT, _Traits, _Allocator> _String;
4075    _LIBCPP_ASSERT(__lhs != nullptr, "operator==(char*, basic_string): received nullptr");
4076    size_t __lhs_len = _Traits::length(__lhs);
4077    if (__lhs_len != __rhs.size()) return false;
4078    return __rhs.compare(0, _String::npos, __lhs, __lhs_len) == 0;
4079}
4080
4081template<class _CharT, class _Traits, class _Allocator>
4082inline _LIBCPP_INLINE_VISIBILITY
4083bool
4084operator==(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
4085           const _CharT* __rhs) _NOEXCEPT
4086{
4087    typedef basic_string<_CharT, _Traits, _Allocator> _String;
4088    _LIBCPP_ASSERT(__rhs != nullptr, "operator==(basic_string, char*): received nullptr");
4089    size_t __rhs_len = _Traits::length(__rhs);
4090    if (__rhs_len != __lhs.size()) return false;
4091    return __lhs.compare(0, _String::npos, __rhs, __rhs_len) == 0;
4092}
4093
4094template<class _CharT, class _Traits, class _Allocator>
4095inline _LIBCPP_INLINE_VISIBILITY
4096bool
4097operator!=(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
4098           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4099{
4100    return !(__lhs == __rhs);
4101}
4102
4103template<class _CharT, class _Traits, class _Allocator>
4104inline _LIBCPP_INLINE_VISIBILITY
4105bool
4106operator!=(const _CharT* __lhs,
4107           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4108{
4109    return !(__lhs == __rhs);
4110}
4111
4112template<class _CharT, class _Traits, class _Allocator>
4113inline _LIBCPP_INLINE_VISIBILITY
4114bool
4115operator!=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4116           const _CharT* __rhs) _NOEXCEPT
4117{
4118    return !(__lhs == __rhs);
4119}
4120
4121// operator<
4122
4123template<class _CharT, class _Traits, class _Allocator>
4124inline _LIBCPP_INLINE_VISIBILITY
4125bool
4126operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4127           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4128{
4129    return __lhs.compare(__rhs) < 0;
4130}
4131
4132template<class _CharT, class _Traits, class _Allocator>
4133inline _LIBCPP_INLINE_VISIBILITY
4134bool
4135operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4136           const _CharT* __rhs) _NOEXCEPT
4137{
4138    return __lhs.compare(__rhs) < 0;
4139}
4140
4141template<class _CharT, class _Traits, class _Allocator>
4142inline _LIBCPP_INLINE_VISIBILITY
4143bool
4144operator< (const _CharT* __lhs,
4145           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4146{
4147    return __rhs.compare(__lhs) > 0;
4148}
4149
4150// operator>
4151
4152template<class _CharT, class _Traits, class _Allocator>
4153inline _LIBCPP_INLINE_VISIBILITY
4154bool
4155operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4156           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4157{
4158    return __rhs < __lhs;
4159}
4160
4161template<class _CharT, class _Traits, class _Allocator>
4162inline _LIBCPP_INLINE_VISIBILITY
4163bool
4164operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4165           const _CharT* __rhs) _NOEXCEPT
4166{
4167    return __rhs < __lhs;
4168}
4169
4170template<class _CharT, class _Traits, class _Allocator>
4171inline _LIBCPP_INLINE_VISIBILITY
4172bool
4173operator> (const _CharT* __lhs,
4174           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4175{
4176    return __rhs < __lhs;
4177}
4178
4179// operator<=
4180
4181template<class _CharT, class _Traits, class _Allocator>
4182inline _LIBCPP_INLINE_VISIBILITY
4183bool
4184operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4185           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4186{
4187    return !(__rhs < __lhs);
4188}
4189
4190template<class _CharT, class _Traits, class _Allocator>
4191inline _LIBCPP_INLINE_VISIBILITY
4192bool
4193operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4194           const _CharT* __rhs) _NOEXCEPT
4195{
4196    return !(__rhs < __lhs);
4197}
4198
4199template<class _CharT, class _Traits, class _Allocator>
4200inline _LIBCPP_INLINE_VISIBILITY
4201bool
4202operator<=(const _CharT* __lhs,
4203           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4204{
4205    return !(__rhs < __lhs);
4206}
4207
4208// operator>=
4209
4210template<class _CharT, class _Traits, class _Allocator>
4211inline _LIBCPP_INLINE_VISIBILITY
4212bool
4213operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4214           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4215{
4216    return !(__lhs < __rhs);
4217}
4218
4219template<class _CharT, class _Traits, class _Allocator>
4220inline _LIBCPP_INLINE_VISIBILITY
4221bool
4222operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4223           const _CharT* __rhs) _NOEXCEPT
4224{
4225    return !(__lhs < __rhs);
4226}
4227
4228template<class _CharT, class _Traits, class _Allocator>
4229inline _LIBCPP_INLINE_VISIBILITY
4230bool
4231operator>=(const _CharT* __lhs,
4232           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4233{
4234    return !(__lhs < __rhs);
4235}
4236
4237// operator +
4238
4239template<class _CharT, class _Traits, class _Allocator>
4240basic_string<_CharT, _Traits, _Allocator>
4241operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4242          const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4243{
4244    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4245    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4246    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4247    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4248    __r.append(__rhs.data(), __rhs_sz);
4249    return __r;
4250}
4251
4252template<class _CharT, class _Traits, class _Allocator>
4253basic_string<_CharT, _Traits, _Allocator>
4254operator+(const _CharT* __lhs , const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4255{
4256    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4257    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = _Traits::length(__lhs);
4258    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4259    __r.__init(__lhs, __lhs_sz, __lhs_sz + __rhs_sz);
4260    __r.append(__rhs.data(), __rhs_sz);
4261    return __r;
4262}
4263
4264template<class _CharT, class _Traits, class _Allocator>
4265basic_string<_CharT, _Traits, _Allocator>
4266operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4267{
4268    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4269    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4270    __r.__init(&__lhs, 1, 1 + __rhs_sz);
4271    __r.append(__rhs.data(), __rhs_sz);
4272    return __r;
4273}
4274
4275template<class _CharT, class _Traits, class _Allocator>
4276inline
4277basic_string<_CharT, _Traits, _Allocator>
4278operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs)
4279{
4280    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4281    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4282    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = _Traits::length(__rhs);
4283    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4284    __r.append(__rhs, __rhs_sz);
4285    return __r;
4286}
4287
4288template<class _CharT, class _Traits, class _Allocator>
4289basic_string<_CharT, _Traits, _Allocator>
4290operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, _CharT __rhs)
4291{
4292    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4293    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4294    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + 1);
4295    __r.push_back(__rhs);
4296    return __r;
4297}
4298
4299#ifndef _LIBCPP_CXX03_LANG
4300
4301template<class _CharT, class _Traits, class _Allocator>
4302inline _LIBCPP_INLINE_VISIBILITY
4303basic_string<_CharT, _Traits, _Allocator>
4304operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4305{
4306    return _VSTD::move(__lhs.append(__rhs));
4307}
4308
4309template<class _CharT, class _Traits, class _Allocator>
4310inline _LIBCPP_INLINE_VISIBILITY
4311basic_string<_CharT, _Traits, _Allocator>
4312operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4313{
4314    return _VSTD::move(__rhs.insert(0, __lhs));
4315}
4316
4317template<class _CharT, class _Traits, class _Allocator>
4318inline _LIBCPP_INLINE_VISIBILITY
4319basic_string<_CharT, _Traits, _Allocator>
4320operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4321{
4322    return _VSTD::move(__lhs.append(__rhs));
4323}
4324
4325template<class _CharT, class _Traits, class _Allocator>
4326inline _LIBCPP_INLINE_VISIBILITY
4327basic_string<_CharT, _Traits, _Allocator>
4328operator+(const _CharT* __lhs , basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4329{
4330    return _VSTD::move(__rhs.insert(0, __lhs));
4331}
4332
4333template<class _CharT, class _Traits, class _Allocator>
4334inline _LIBCPP_INLINE_VISIBILITY
4335basic_string<_CharT, _Traits, _Allocator>
4336operator+(_CharT __lhs, basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4337{
4338    __rhs.insert(__rhs.begin(), __lhs);
4339    return _VSTD::move(__rhs);
4340}
4341
4342template<class _CharT, class _Traits, class _Allocator>
4343inline _LIBCPP_INLINE_VISIBILITY
4344basic_string<_CharT, _Traits, _Allocator>
4345operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const _CharT* __rhs)
4346{
4347    return _VSTD::move(__lhs.append(__rhs));
4348}
4349
4350template<class _CharT, class _Traits, class _Allocator>
4351inline _LIBCPP_INLINE_VISIBILITY
4352basic_string<_CharT, _Traits, _Allocator>
4353operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, _CharT __rhs)
4354{
4355    __lhs.push_back(__rhs);
4356    return _VSTD::move(__lhs);
4357}
4358
4359#endif // _LIBCPP_CXX03_LANG
4360
4361// swap
4362
4363template<class _CharT, class _Traits, class _Allocator>
4364inline _LIBCPP_INLINE_VISIBILITY
4365void
4366swap(basic_string<_CharT, _Traits, _Allocator>& __lhs,
4367     basic_string<_CharT, _Traits, _Allocator>& __rhs)
4368     _NOEXCEPT_(_NOEXCEPT_(__lhs.swap(__rhs)))
4369{
4370    __lhs.swap(__rhs);
4371}
4372
4373_LIBCPP_FUNC_VIS int                stoi  (const string& __str, size_t* __idx = nullptr, int __base = 10);
4374_LIBCPP_FUNC_VIS long               stol  (const string& __str, size_t* __idx = nullptr, int __base = 10);
4375_LIBCPP_FUNC_VIS unsigned long      stoul (const string& __str, size_t* __idx = nullptr, int __base = 10);
4376_LIBCPP_FUNC_VIS long long          stoll (const string& __str, size_t* __idx = nullptr, int __base = 10);
4377_LIBCPP_FUNC_VIS unsigned long long stoull(const string& __str, size_t* __idx = nullptr, int __base = 10);
4378
4379_LIBCPP_FUNC_VIS float       stof (const string& __str, size_t* __idx = nullptr);
4380_LIBCPP_FUNC_VIS double      stod (const string& __str, size_t* __idx = nullptr);
4381_LIBCPP_FUNC_VIS long double stold(const string& __str, size_t* __idx = nullptr);
4382
4383_LIBCPP_FUNC_VIS string to_string(int __val);
4384_LIBCPP_FUNC_VIS string to_string(unsigned __val);
4385_LIBCPP_FUNC_VIS string to_string(long __val);
4386_LIBCPP_FUNC_VIS string to_string(unsigned long __val);
4387_LIBCPP_FUNC_VIS string to_string(long long __val);
4388_LIBCPP_FUNC_VIS string to_string(unsigned long long __val);
4389_LIBCPP_FUNC_VIS string to_string(float __val);
4390_LIBCPP_FUNC_VIS string to_string(double __val);
4391_LIBCPP_FUNC_VIS string to_string(long double __val);
4392
4393#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
4394_LIBCPP_FUNC_VIS int                stoi  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4395_LIBCPP_FUNC_VIS long               stol  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4396_LIBCPP_FUNC_VIS unsigned long      stoul (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4397_LIBCPP_FUNC_VIS long long          stoll (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4398_LIBCPP_FUNC_VIS unsigned long long stoull(const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4399
4400_LIBCPP_FUNC_VIS float       stof (const wstring& __str, size_t* __idx = nullptr);
4401_LIBCPP_FUNC_VIS double      stod (const wstring& __str, size_t* __idx = nullptr);
4402_LIBCPP_FUNC_VIS long double stold(const wstring& __str, size_t* __idx = nullptr);
4403
4404_LIBCPP_FUNC_VIS wstring to_wstring(int __val);
4405_LIBCPP_FUNC_VIS wstring to_wstring(unsigned __val);
4406_LIBCPP_FUNC_VIS wstring to_wstring(long __val);
4407_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long __val);
4408_LIBCPP_FUNC_VIS wstring to_wstring(long long __val);
4409_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long long __val);
4410_LIBCPP_FUNC_VIS wstring to_wstring(float __val);
4411_LIBCPP_FUNC_VIS wstring to_wstring(double __val);
4412_LIBCPP_FUNC_VIS wstring to_wstring(long double __val);
4413#endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
4414
4415template<class _CharT, class _Traits, class _Allocator>
4416_LIBCPP_TEMPLATE_DATA_VIS
4417const typename basic_string<_CharT, _Traits, _Allocator>::size_type
4418               basic_string<_CharT, _Traits, _Allocator>::npos;
4419
4420template <class _CharT, class _Allocator>
4421struct _LIBCPP_TEMPLATE_VIS
4422    hash<basic_string<_CharT, char_traits<_CharT>, _Allocator> >
4423    : public unary_function<
4424          basic_string<_CharT, char_traits<_CharT>, _Allocator>, size_t>
4425{
4426    size_t
4427    operator()(const basic_string<_CharT, char_traits<_CharT>, _Allocator>& __val) const _NOEXCEPT
4428    { return __do_string_hash(__val.data(), __val.data() + __val.size()); }
4429};
4430
4431
4432template<class _CharT, class _Traits, class _Allocator>
4433basic_ostream<_CharT, _Traits>&
4434operator<<(basic_ostream<_CharT, _Traits>& __os,
4435           const basic_string<_CharT, _Traits, _Allocator>& __str);
4436
4437template<class _CharT, class _Traits, class _Allocator>
4438basic_istream<_CharT, _Traits>&
4439operator>>(basic_istream<_CharT, _Traits>& __is,
4440           basic_string<_CharT, _Traits, _Allocator>& __str);
4441
4442template<class _CharT, class _Traits, class _Allocator>
4443basic_istream<_CharT, _Traits>&
4444getline(basic_istream<_CharT, _Traits>& __is,
4445        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4446
4447template<class _CharT, class _Traits, class _Allocator>
4448inline _LIBCPP_INLINE_VISIBILITY
4449basic_istream<_CharT, _Traits>&
4450getline(basic_istream<_CharT, _Traits>& __is,
4451        basic_string<_CharT, _Traits, _Allocator>& __str);
4452
4453template<class _CharT, class _Traits, class _Allocator>
4454inline _LIBCPP_INLINE_VISIBILITY
4455basic_istream<_CharT, _Traits>&
4456getline(basic_istream<_CharT, _Traits>&& __is,
4457        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4458
4459template<class _CharT, class _Traits, class _Allocator>
4460inline _LIBCPP_INLINE_VISIBILITY
4461basic_istream<_CharT, _Traits>&
4462getline(basic_istream<_CharT, _Traits>&& __is,
4463        basic_string<_CharT, _Traits, _Allocator>& __str);
4464
4465#if _LIBCPP_STD_VER > 17
4466template <class _CharT, class _Traits, class _Allocator, class _Up>
4467inline _LIBCPP_INLINE_VISIBILITY
4468    typename basic_string<_CharT, _Traits, _Allocator>::size_type
4469    erase(basic_string<_CharT, _Traits, _Allocator>& __str, const _Up& __v) {
4470  auto __old_size = __str.size();
4471  __str.erase(_VSTD::remove(__str.begin(), __str.end(), __v), __str.end());
4472  return __old_size - __str.size();
4473}
4474
4475template <class _CharT, class _Traits, class _Allocator, class _Predicate>
4476inline _LIBCPP_INLINE_VISIBILITY
4477    typename basic_string<_CharT, _Traits, _Allocator>::size_type
4478    erase_if(basic_string<_CharT, _Traits, _Allocator>& __str,
4479             _Predicate __pred) {
4480  auto __old_size = __str.size();
4481  __str.erase(_VSTD::remove_if(__str.begin(), __str.end(), __pred),
4482              __str.end());
4483  return __old_size - __str.size();
4484}
4485#endif
4486
4487#if _LIBCPP_DEBUG_LEVEL == 2
4488
4489template<class _CharT, class _Traits, class _Allocator>
4490bool
4491basic_string<_CharT, _Traits, _Allocator>::__dereferenceable(const const_iterator* __i) const
4492{
4493    return this->data() <= _VSTD::__to_address(__i->base()) &&
4494           _VSTD::__to_address(__i->base()) < this->data() + this->size();
4495}
4496
4497template<class _CharT, class _Traits, class _Allocator>
4498bool
4499basic_string<_CharT, _Traits, _Allocator>::__decrementable(const const_iterator* __i) const
4500{
4501    return this->data() < _VSTD::__to_address(__i->base()) &&
4502           _VSTD::__to_address(__i->base()) <= this->data() + this->size();
4503}
4504
4505template<class _CharT, class _Traits, class _Allocator>
4506bool
4507basic_string<_CharT, _Traits, _Allocator>::__addable(const const_iterator* __i, ptrdiff_t __n) const
4508{
4509    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4510    return this->data() <= __p && __p <= this->data() + this->size();
4511}
4512
4513template<class _CharT, class _Traits, class _Allocator>
4514bool
4515basic_string<_CharT, _Traits, _Allocator>::__subscriptable(const const_iterator* __i, ptrdiff_t __n) const
4516{
4517    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4518    return this->data() <= __p && __p < this->data() + this->size();
4519}
4520
4521#endif // _LIBCPP_DEBUG_LEVEL == 2
4522
4523#if _LIBCPP_STD_VER > 11
4524// Literal suffixes for basic_string [basic.string.literals]
4525inline namespace literals
4526{
4527  inline namespace string_literals
4528  {
4529    inline _LIBCPP_INLINE_VISIBILITY
4530    basic_string<char> operator "" s( const char *__str, size_t __len )
4531    {
4532        return basic_string<char> (__str, __len);
4533    }
4534
4535#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
4536    inline _LIBCPP_INLINE_VISIBILITY
4537    basic_string<wchar_t> operator "" s( const wchar_t *__str, size_t __len )
4538    {
4539        return basic_string<wchar_t> (__str, __len);
4540    }
4541#endif
4542
4543#ifndef _LIBCPP_HAS_NO_CHAR8_T
4544    inline _LIBCPP_INLINE_VISIBILITY
4545    basic_string<char8_t> operator "" s(const char8_t *__str, size_t __len) _NOEXCEPT
4546    {
4547        return basic_string<char8_t> (__str, __len);
4548    }
4549#endif
4550
4551    inline _LIBCPP_INLINE_VISIBILITY
4552    basic_string<char16_t> operator "" s( const char16_t *__str, size_t __len )
4553    {
4554        return basic_string<char16_t> (__str, __len);
4555    }
4556
4557    inline _LIBCPP_INLINE_VISIBILITY
4558    basic_string<char32_t> operator "" s( const char32_t *__str, size_t __len )
4559    {
4560        return basic_string<char32_t> (__str, __len);
4561    }
4562  } // namespace string_literals
4563} // namespace literals
4564#endif
4565
4566_LIBCPP_END_NAMESPACE_STD
4567
4568_LIBCPP_POP_MACROS
4569
4570#endif // _LIBCPP_STRING
4571