xref: /llvm-project-15.0.7/libcxx/include/string (revision ec62bf2f)
1// -*- C++ -*-
2//===--------------------------- string -----------------------------------===//
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>;
72
73template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
74class basic_string
75{
76public:
77// types:
78    typedef traits traits_type;
79    typedef typename traits_type::char_type value_type;
80    typedef Allocator allocator_type;
81    typedef typename allocator_type::size_type size_type;
82    typedef typename allocator_type::difference_type difference_type;
83    typedef typename allocator_type::reference reference;
84    typedef typename allocator_type::const_reference const_reference;
85    typedef typename allocator_type::pointer pointer;
86    typedef typename allocator_type::const_pointer const_pointer;
87    typedef implementation-defined iterator;
88    typedef implementation-defined const_iterator;
89    typedef std::reverse_iterator<iterator> reverse_iterator;
90    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
91
92    static const size_type npos = -1;
93
94    basic_string()
95        noexcept(is_nothrow_default_constructible<allocator_type>::value);
96    explicit basic_string(const allocator_type& a);
97    basic_string(const basic_string& str);
98    basic_string(basic_string&& str)
99        noexcept(is_nothrow_move_constructible<allocator_type>::value);
100    basic_string(const basic_string& str, size_type pos,
101                 const allocator_type& a = allocator_type());
102    basic_string(const basic_string& str, size_type pos, size_type n,
103                 const Allocator& a = Allocator());
104    template<class T>
105        basic_string(const T& t, size_type pos, size_type n, const Allocator& a = Allocator()); // C++17
106    template <class T>
107        explicit basic_string(const T& t, const Allocator& a = Allocator()); // C++17
108    basic_string(const value_type* s, const allocator_type& a = allocator_type());
109    basic_string(const value_type* s, size_type n, const allocator_type& a = allocator_type());
110    basic_string(size_type n, value_type c, const allocator_type& a = allocator_type());
111    template<class InputIterator>
112        basic_string(InputIterator begin, InputIterator end,
113                     const allocator_type& a = allocator_type());
114    basic_string(initializer_list<value_type>, const Allocator& = Allocator());
115    basic_string(const basic_string&, const Allocator&);
116    basic_string(basic_string&&, const Allocator&);
117
118    ~basic_string();
119
120    operator basic_string_view<charT, traits>() const noexcept;
121
122    basic_string& operator=(const basic_string& str);
123    template <class T>
124        basic_string& operator=(const T& t); // C++17
125    basic_string& operator=(basic_string&& str)
126        noexcept(
127             allocator_type::propagate_on_container_move_assignment::value ||
128             allocator_type::is_always_equal::value ); // C++17
129    basic_string& operator=(const value_type* s);
130    basic_string& operator=(value_type c);
131    basic_string& operator=(initializer_list<value_type>);
132
133    iterator       begin() noexcept;
134    const_iterator begin() const noexcept;
135    iterator       end() noexcept;
136    const_iterator end() const noexcept;
137
138    reverse_iterator       rbegin() noexcept;
139    const_reverse_iterator rbegin() const noexcept;
140    reverse_iterator       rend() noexcept;
141    const_reverse_iterator rend() const noexcept;
142
143    const_iterator         cbegin() const noexcept;
144    const_iterator         cend() const noexcept;
145    const_reverse_iterator crbegin() const noexcept;
146    const_reverse_iterator crend() const noexcept;
147
148    size_type size() const noexcept;
149    size_type length() const noexcept;
150    size_type max_size() const noexcept;
151    size_type capacity() const noexcept;
152
153    void resize(size_type n, value_type c);
154    void resize(size_type n);
155
156    void reserve(size_type res_arg = 0);
157    void shrink_to_fit();
158    void clear() noexcept;
159    bool empty() const noexcept;
160
161    const_reference operator[](size_type pos) const;
162    reference       operator[](size_type pos);
163
164    const_reference at(size_type n) const;
165    reference       at(size_type n);
166
167    basic_string& operator+=(const basic_string& str);
168    template <class T>
169        basic_string& operator+=(const T& t);              // C++17
170    basic_string& operator+=(const value_type* s);
171    basic_string& operator+=(value_type c);
172    basic_string& operator+=(initializer_list<value_type>);
173
174    basic_string& append(const basic_string& str);
175    template <class T>
176        basic_string& append(const T& t);                 // C++17
177    basic_string& append(const basic_string& str, size_type pos, size_type n=npos); //C++14
178    template <class T>
179        basic_string& append(const T& t, size_type pos, size_type n=npos); // C++17
180    basic_string& append(const value_type* s, size_type n);
181    basic_string& append(const value_type* s);
182    basic_string& append(size_type n, value_type c);
183    template<class InputIterator>
184        basic_string& append(InputIterator first, InputIterator last);
185    basic_string& append(initializer_list<value_type>);
186
187    void push_back(value_type c);
188    void pop_back();
189    reference       front();
190    const_reference front() const;
191    reference       back();
192    const_reference back() const;
193
194    basic_string& assign(const basic_string& str);
195    template <class T>
196        basic_string& assign(const T& t);  // C++17
197    basic_string& assign(basic_string&& str);
198    basic_string& assign(const basic_string& str, size_type pos, size_type n=npos); // C++14
199    template <class T>
200        basic_string& assign(const T& t, size_type pos, size_type n=npos); // C++17
201    basic_string& assign(const value_type* s, size_type n);
202    basic_string& assign(const value_type* s);
203    basic_string& assign(size_type n, value_type c);
204    template<class InputIterator>
205        basic_string& assign(InputIterator first, InputIterator last);
206    basic_string& assign(initializer_list<value_type>);
207
208    basic_string& insert(size_type pos1, const basic_string& str);
209    template <class T>
210        basic_string& insert(size_type pos1, const T& t);
211    basic_string& insert(size_type pos1, const basic_string& str,
212                         size_type pos2, size_type n);
213    template <class T>
214        basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n); // C++17
215    basic_string& insert(size_type pos, const value_type* s, size_type n=npos); //C++14
216    basic_string& insert(size_type pos, const value_type* s);
217    basic_string& insert(size_type pos, size_type n, value_type c);
218    iterator      insert(const_iterator p, value_type c);
219    iterator      insert(const_iterator p, size_type n, value_type c);
220    template<class InputIterator>
221        iterator insert(const_iterator p, InputIterator first, InputIterator last);
222    iterator      insert(const_iterator p, initializer_list<value_type>);
223
224    basic_string& erase(size_type pos = 0, size_type n = npos);
225    iterator      erase(const_iterator position);
226    iterator      erase(const_iterator first, const_iterator last);
227
228    basic_string& replace(size_type pos1, size_type n1, const basic_string& str);
229    template <class T>
230    basic_string& replace(size_type pos1, size_type n1, const T& t);  // C++17
231    basic_string& replace(size_type pos1, size_type n1, const basic_string& str,
232                          size_type pos2, size_type n2=npos); // C++14
233    template <class T>
234        basic_string& replace(size_type pos1, size_type n1, const T& t,
235                              size_type pos2, size_type n); // C++17
236    basic_string& replace(size_type pos, size_type n1, const value_type* s, size_type n2);
237    basic_string& replace(size_type pos, size_type n1, const value_type* s);
238    basic_string& replace(size_type pos, size_type n1, size_type n2, value_type c);
239    basic_string& replace(const_iterator i1, const_iterator i2, const basic_string& str);
240    template <class T>
241        basic_string& replace(const_iterator i1, const_iterator i2, const T& t);  // C++17
242    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s, size_type n);
243    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s);
244    basic_string& replace(const_iterator i1, const_iterator i2, size_type n, value_type c);
245    template<class InputIterator>
246        basic_string& replace(const_iterator i1, const_iterator i2, InputIterator j1, InputIterator j2);
247    basic_string& replace(const_iterator i1, const_iterator i2, initializer_list<value_type>);
248
249    size_type copy(value_type* s, size_type n, size_type pos = 0) const;
250    basic_string substr(size_type pos = 0, size_type n = npos) const;
251
252    void swap(basic_string& str)
253        noexcept(allocator_traits<allocator_type>::propagate_on_container_swap::value ||
254                 allocator_traits<allocator_type>::is_always_equal::value);  // C++17
255
256    const value_type* c_str() const noexcept;
257    const value_type* data() const noexcept;
258          value_type* data()       noexcept;   // C++17
259
260    allocator_type get_allocator() const noexcept;
261
262    size_type find(const basic_string& str, size_type pos = 0) const noexcept;
263    template <class T>
264        size_type find(const T& t, size_type pos = 0) const;  // C++17
265    size_type find(const value_type* s, size_type pos, size_type n) const noexcept;
266    size_type find(const value_type* s, size_type pos = 0) const noexcept;
267    size_type find(value_type c, size_type pos = 0) const noexcept;
268
269    size_type rfind(const basic_string& str, size_type pos = npos) const noexcept;
270    template <class T>
271        size_type rfind(const T& t, size_type pos = npos) const;  // C++17
272    size_type rfind(const value_type* s, size_type pos, size_type n) const noexcept;
273    size_type rfind(const value_type* s, size_type pos = npos) const noexcept;
274    size_type rfind(value_type c, size_type pos = npos) const noexcept;
275
276    size_type find_first_of(const basic_string& str, size_type pos = 0) const noexcept;
277    template <class T>
278        size_type find_first_of(const T& t, size_type pos = 0) const; // C++17
279    size_type find_first_of(const value_type* s, size_type pos, size_type n) const noexcept;
280    size_type find_first_of(const value_type* s, size_type pos = 0) const noexcept;
281    size_type find_first_of(value_type c, size_type pos = 0) const noexcept;
282
283    size_type find_last_of(const basic_string& str, size_type pos = npos) const noexcept;
284    template <class T>
285        size_type find_last_of(const T& t, size_type pos = npos) const noexcept;  // C++17
286    size_type find_last_of(const value_type* s, size_type pos, size_type n) const noexcept;
287    size_type find_last_of(const value_type* s, size_type pos = npos) const noexcept;
288    size_type find_last_of(value_type c, size_type pos = npos) const noexcept;
289
290    size_type find_first_not_of(const basic_string& str, size_type pos = 0) const noexcept;
291    template <class T>
292        size_type find_first_not_of(const T& t, size_type pos = 0) const; // C++17
293    size_type find_first_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
294    size_type find_first_not_of(const value_type* s, size_type pos = 0) const noexcept;
295    size_type find_first_not_of(value_type c, size_type pos = 0) const noexcept;
296
297    size_type find_last_not_of(const basic_string& str, size_type pos = npos) const noexcept;
298    template <class T>
299        size_type find_last_not_of(const T& t, size_type pos = npos) const; // C++17
300    size_type find_last_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
301    size_type find_last_not_of(const value_type* s, size_type pos = npos) const noexcept;
302    size_type find_last_not_of(value_type c, size_type pos = npos) const noexcept;
303
304    int compare(const basic_string& str) const noexcept;
305    template <class T>
306        int compare(const T& t) const noexcept;  // C++17
307    int compare(size_type pos1, size_type n1, const basic_string& str) const;
308    template <class T>
309        int compare(size_type pos1, size_type n1, const T& t) const;  // C++17
310    int compare(size_type pos1, size_type n1, const basic_string& str,
311                size_type pos2, size_type n2=npos) const; // C++14
312    template <class T>
313        int compare(size_type pos1, size_type n1, const T& t,
314                    size_type pos2, size_type n2=npos) const; // C++17
315    int compare(const value_type* s) const noexcept;
316    int compare(size_type pos1, size_type n1, const value_type* s) const;
317    int compare(size_type pos1, size_type n1, const value_type* s, size_type n2) const;
318
319    bool starts_with(basic_string_view<charT, traits> sv) const noexcept; // C++2a
320    bool starts_with(charT c) const noexcept;                             // C++2a
321    bool starts_with(const charT* s) const;                               // C++2a
322    bool ends_with(basic_string_view<charT, traits> sv) const noexcept;   // C++2a
323    bool ends_with(charT c) const noexcept;                               // C++2a
324    bool ends_with(const charT* s) const;                                 // C++2a
325
326    bool __invariants() const;
327};
328
329template<class InputIterator,
330         class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
331basic_string(InputIterator, InputIterator, Allocator = Allocator())
332   -> basic_string<typename iterator_traits<InputIterator>::value_type,
333                  char_traits<typename iterator_traits<InputIterator>::value_type>,
334                  Allocator>;   // C++17
335
336template<class charT, class traits, class Allocator>
337basic_string<charT, traits, Allocator>
338operator+(const basic_string<charT, traits, Allocator>& lhs,
339          const basic_string<charT, traits, Allocator>& rhs);
340
341template<class charT, class traits, class Allocator>
342basic_string<charT, traits, Allocator>
343operator+(const charT* lhs , const basic_string<charT,traits,Allocator>&rhs);
344
345template<class charT, class traits, class Allocator>
346basic_string<charT, traits, Allocator>
347operator+(charT lhs, const basic_string<charT,traits,Allocator>& rhs);
348
349template<class charT, class traits, class Allocator>
350basic_string<charT, traits, Allocator>
351operator+(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs);
352
353template<class charT, class traits, class Allocator>
354basic_string<charT, traits, Allocator>
355operator+(const basic_string<charT, traits, Allocator>& lhs, charT rhs);
356
357template<class charT, class traits, class Allocator>
358bool operator==(const basic_string<charT, traits, Allocator>& lhs,
359                const basic_string<charT, traits, Allocator>& rhs) noexcept;
360
361template<class charT, class traits, class Allocator>
362bool operator==(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
363
364template<class charT, class traits, class Allocator>
365bool operator==(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs) noexcept;
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 basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
383
384template<class charT, class traits, class Allocator>
385bool operator< (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
386
387template<class charT, class traits, class Allocator>
388bool operator> (const basic_string<charT, traits, Allocator>& lhs,
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>
418void swap(basic_string<charT, traits, Allocator>& lhs,
419          basic_string<charT, traits, Allocator>& rhs)
420            noexcept(noexcept(lhs.swap(rhs)));
421
422template<class charT, class traits, class Allocator>
423basic_istream<charT, traits>&
424operator>>(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);
425
426template<class charT, class traits, class Allocator>
427basic_ostream<charT, traits>&
428operator<<(basic_ostream<charT, traits>& os, const basic_string<charT, traits, Allocator>& str);
429
430template<class charT, class traits, class Allocator>
431basic_istream<charT, traits>&
432getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str,
433        charT delim);
434
435template<class charT, class traits, class Allocator>
436basic_istream<charT, traits>&
437getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);
438
439template<class charT, class traits, class Allocator, class U>
440void erase(basic_string<charT, traits, Allocator>& c, const U& value); // C++20
441template<class charT, class traits, class Allocator, class Predicate>
442void erase_if(basic_string<charT, traits, Allocator>& c, Predicate pred); // C++20
443
444typedef basic_string<char>    string;
445typedef basic_string<wchar_t> wstring;
446typedef basic_string<char16_t> u16string;
447typedef basic_string<char32_t> u32string;
448
449int                stoi  (const string& str, size_t* idx = 0, int base = 10);
450long               stol  (const string& str, size_t* idx = 0, int base = 10);
451unsigned long      stoul (const string& str, size_t* idx = 0, int base = 10);
452long long          stoll (const string& str, size_t* idx = 0, int base = 10);
453unsigned long long stoull(const string& str, size_t* idx = 0, int base = 10);
454
455float       stof (const string& str, size_t* idx = 0);
456double      stod (const string& str, size_t* idx = 0);
457long double stold(const string& str, size_t* idx = 0);
458
459string to_string(int val);
460string to_string(unsigned val);
461string to_string(long val);
462string to_string(unsigned long val);
463string to_string(long long val);
464string to_string(unsigned long long val);
465string to_string(float val);
466string to_string(double val);
467string to_string(long double val);
468
469int                stoi  (const wstring& str, size_t* idx = 0, int base = 10);
470long               stol  (const wstring& str, size_t* idx = 0, int base = 10);
471unsigned long      stoul (const wstring& str, size_t* idx = 0, int base = 10);
472long long          stoll (const wstring& str, size_t* idx = 0, int base = 10);
473unsigned long long stoull(const wstring& str, size_t* idx = 0, int base = 10);
474
475float       stof (const wstring& str, size_t* idx = 0);
476double      stod (const wstring& str, size_t* idx = 0);
477long double stold(const wstring& str, size_t* idx = 0);
478
479wstring to_wstring(int val);
480wstring to_wstring(unsigned val);
481wstring to_wstring(long val);
482wstring to_wstring(unsigned long val);
483wstring to_wstring(long long val);
484wstring to_wstring(unsigned long long val);
485wstring to_wstring(float val);
486wstring to_wstring(double val);
487wstring to_wstring(long double val);
488
489template <> struct hash<string>;
490template <> struct hash<u16string>;
491template <> struct hash<u32string>;
492template <> struct hash<wstring>;
493
494basic_string<char>     operator "" s( const char *str,     size_t len ); // C++14
495basic_string<wchar_t>  operator "" s( const wchar_t *str,  size_t len ); // C++14
496basic_string<char16_t> operator "" s( const char16_t *str, size_t len ); // C++14
497basic_string<char32_t> operator "" s( const char32_t *str, size_t len ); // C++14
498
499}  // std
500
501*/
502
503#include <__config>
504#include <string_view>
505#include <iosfwd>
506#include <cstring>
507#include <cstdio>  // For EOF.
508#include <cwchar>
509#include <algorithm>
510#include <iterator>
511#include <utility>
512#include <memory>
513#include <stdexcept>
514#include <type_traits>
515#include <initializer_list>
516#include <__functional_base>
517#include <version>
518#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
519#include <cstdint>
520#endif
521
522#include <__debug>
523
524#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
525#pragma GCC system_header
526#endif
527
528_LIBCPP_PUSH_MACROS
529#include <__undef_macros>
530
531
532_LIBCPP_BEGIN_NAMESPACE_STD
533
534// fpos
535
536template <class _StateT>
537class _LIBCPP_TEMPLATE_VIS fpos
538{
539private:
540    _StateT __st_;
541    streamoff __off_;
542public:
543    _LIBCPP_INLINE_VISIBILITY fpos(streamoff __off = streamoff()) : __st_(), __off_(__off) {}
544
545    _LIBCPP_INLINE_VISIBILITY operator streamoff() const {return __off_;}
546
547    _LIBCPP_INLINE_VISIBILITY _StateT state() const {return __st_;}
548    _LIBCPP_INLINE_VISIBILITY void state(_StateT __st) {__st_ = __st;}
549
550    _LIBCPP_INLINE_VISIBILITY fpos& operator+=(streamoff __off) {__off_ += __off; return *this;}
551    _LIBCPP_INLINE_VISIBILITY fpos  operator+ (streamoff __off) const {fpos __t(*this); __t += __off; return __t;}
552    _LIBCPP_INLINE_VISIBILITY fpos& operator-=(streamoff __off) {__off_ -= __off; return *this;}
553    _LIBCPP_INLINE_VISIBILITY fpos  operator- (streamoff __off) const {fpos __t(*this); __t -= __off; return __t;}
554};
555
556template <class _StateT>
557inline _LIBCPP_INLINE_VISIBILITY
558streamoff operator-(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
559    {return streamoff(__x) - streamoff(__y);}
560
561template <class _StateT>
562inline _LIBCPP_INLINE_VISIBILITY
563bool operator==(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
564    {return streamoff(__x) == streamoff(__y);}
565
566template <class _StateT>
567inline _LIBCPP_INLINE_VISIBILITY
568bool operator!=(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
569    {return streamoff(__x) != streamoff(__y);}
570
571// basic_string
572
573template<class _CharT, class _Traits, class _Allocator>
574basic_string<_CharT, _Traits, _Allocator>
575operator+(const basic_string<_CharT, _Traits, _Allocator>& __x,
576          const basic_string<_CharT, _Traits, _Allocator>& __y);
577
578template<class _CharT, class _Traits, class _Allocator>
579basic_string<_CharT, _Traits, _Allocator>
580operator+(const _CharT* __x, const basic_string<_CharT,_Traits,_Allocator>& __y);
581
582template<class _CharT, class _Traits, class _Allocator>
583basic_string<_CharT, _Traits, _Allocator>
584operator+(_CharT __x, const basic_string<_CharT,_Traits,_Allocator>& __y);
585
586template<class _CharT, class _Traits, class _Allocator>
587inline _LIBCPP_INLINE_VISIBILITY
588basic_string<_CharT, _Traits, _Allocator>
589operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, const _CharT* __y);
590
591template<class _CharT, class _Traits, class _Allocator>
592basic_string<_CharT, _Traits, _Allocator>
593operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, _CharT __y);
594
595_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS string operator+<char, char_traits<char>, allocator<char> >(char const*, string const&))
596
597template <bool>
598class _LIBCPP_TEMPLATE_VIS __basic_string_common
599{
600protected:
601    _LIBCPP_NORETURN void __throw_length_error() const;
602    _LIBCPP_NORETURN void __throw_out_of_range() const;
603};
604
605template <bool __b>
606void
607__basic_string_common<__b>::__throw_length_error() const
608{
609    _VSTD::__throw_length_error("basic_string");
610}
611
612template <bool __b>
613void
614__basic_string_common<__b>::__throw_out_of_range() const
615{
616    _VSTD::__throw_out_of_range("basic_string");
617}
618
619_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS __basic_string_common<true>)
620
621#ifdef _LIBCPP_NO_EXCEPTIONS
622template <class _Iter>
623struct __libcpp_string_gets_noexcept_iterator_impl : public true_type {};
624#elif defined(_LIBCPP_HAS_NO_NOEXCEPT)
625template <class _Iter>
626struct __libcpp_string_gets_noexcept_iterator_impl : public false_type {};
627#else
628template <class _Iter, bool = __is_cpp17_forward_iterator<_Iter>::value>
629struct __libcpp_string_gets_noexcept_iterator_impl : public _LIBCPP_BOOL_CONSTANT((
630    noexcept(++(declval<_Iter&>())) &&
631    is_nothrow_assignable<_Iter&, _Iter>::value &&
632    noexcept(declval<_Iter>() == declval<_Iter>()) &&
633    noexcept(*declval<_Iter>())
634)) {};
635
636template <class _Iter>
637struct __libcpp_string_gets_noexcept_iterator_impl<_Iter, false> : public false_type {};
638#endif
639
640
641template <class _Iter>
642struct __libcpp_string_gets_noexcept_iterator
643    : public _LIBCPP_BOOL_CONSTANT(__libcpp_is_trivial_iterator<_Iter>::value || __libcpp_string_gets_noexcept_iterator_impl<_Iter>::value) {};
644
645template <class _CharT, class _Traits, class _Tp>
646struct __can_be_converted_to_string_view : public _BoolConstant<
647      is_convertible<const _Tp&, basic_string_view<_CharT, _Traits> >::value &&
648     !is_convertible<const _Tp&, const _CharT*>::value
649    > {};
650
651#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
652
653template <class _CharT, size_t = sizeof(_CharT)>
654struct __padding
655{
656    unsigned char __xx[sizeof(_CharT)-1];
657};
658
659template <class _CharT>
660struct __padding<_CharT, 1>
661{
662};
663
664#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
665
666template<class _CharT, class _Traits, class _Allocator>
667class _LIBCPP_TEMPLATE_VIS basic_string
668    : private __basic_string_common<true>
669{
670public:
671    typedef basic_string                                 __self;
672    typedef basic_string_view<_CharT, _Traits>           __self_view;
673    typedef _Traits                                      traits_type;
674    typedef _CharT                                       value_type;
675    typedef _Allocator                                   allocator_type;
676    typedef allocator_traits<allocator_type>             __alloc_traits;
677    typedef typename __alloc_traits::size_type           size_type;
678    typedef typename __alloc_traits::difference_type     difference_type;
679    typedef value_type&                                  reference;
680    typedef const value_type&                            const_reference;
681    typedef typename __alloc_traits::pointer             pointer;
682    typedef typename __alloc_traits::const_pointer       const_pointer;
683
684    static_assert((!is_array<value_type>::value), "Character type of basic_string must not be an array");
685    static_assert(( is_standard_layout<value_type>::value), "Character type of basic_string must be standard-layout");
686    static_assert(( is_trivial<value_type>::value), "Character type of basic_string must be trivial");
687    static_assert(( is_same<_CharT, typename traits_type::char_type>::value),
688                  "traits_type::char_type must be the same type as CharT");
689    static_assert(( is_same<typename allocator_type::value_type, value_type>::value),
690                  "Allocator::value_type must be same type as value_type");
691
692#if defined(_LIBCPP_RAW_ITERATORS)
693    typedef pointer                                      iterator;
694    typedef const_pointer                                const_iterator;
695#else  // defined(_LIBCPP_RAW_ITERATORS)
696    typedef __wrap_iter<pointer>                         iterator;
697    typedef __wrap_iter<const_pointer>                   const_iterator;
698#endif  // defined(_LIBCPP_RAW_ITERATORS)
699    typedef _VSTD::reverse_iterator<iterator>             reverse_iterator;
700    typedef _VSTD::reverse_iterator<const_iterator>       const_reverse_iterator;
701
702private:
703
704#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
705
706    struct __long
707    {
708        pointer   __data_;
709        size_type __size_;
710        size_type __cap_;
711    };
712
713#ifdef _LIBCPP_BIG_ENDIAN
714    static const size_type __short_mask = 0x01;
715    static const size_type __long_mask  = 0x1ul;
716#else  // _LIBCPP_BIG_ENDIAN
717    static const size_type __short_mask = 0x80;
718    static const size_type __long_mask  = ~(size_type(~0) >> 1);
719#endif  // _LIBCPP_BIG_ENDIAN
720
721    enum {__min_cap = (sizeof(__long) - 1)/sizeof(value_type) > 2 ?
722                      (sizeof(__long) - 1)/sizeof(value_type) : 2};
723
724    struct __short
725    {
726        value_type __data_[__min_cap];
727        struct
728            : __padding<value_type>
729        {
730            unsigned char __size_;
731        };
732    };
733
734#else
735
736    struct __long
737    {
738        size_type __cap_;
739        size_type __size_;
740        pointer   __data_;
741    };
742
743#ifdef _LIBCPP_BIG_ENDIAN
744    static const size_type __short_mask = 0x80;
745    static const size_type __long_mask  = ~(size_type(~0) >> 1);
746#else  // _LIBCPP_BIG_ENDIAN
747    static const size_type __short_mask = 0x01;
748    static const size_type __long_mask  = 0x1ul;
749#endif  // _LIBCPP_BIG_ENDIAN
750
751    enum {__min_cap = (sizeof(__long) - 1)/sizeof(value_type) > 2 ?
752                      (sizeof(__long) - 1)/sizeof(value_type) : 2};
753
754    struct __short
755    {
756        union
757        {
758            unsigned char __size_;
759            value_type __lx;
760        };
761        value_type __data_[__min_cap];
762    };
763
764#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
765
766    union __ulx{__long __lx; __short __lxx;};
767
768    enum {__n_words = sizeof(__ulx) / sizeof(size_type)};
769
770    struct __raw
771    {
772        size_type __words[__n_words];
773    };
774
775    struct __rep
776    {
777        union
778        {
779            __long  __l;
780            __short __s;
781            __raw   __r;
782        };
783    };
784
785    __compressed_pair<__rep, allocator_type> __r_;
786
787public:
788    _LIBCPP_FUNC_VIS
789    static const size_type npos = -1;
790
791    _LIBCPP_INLINE_VISIBILITY basic_string()
792        _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
793
794    _LIBCPP_INLINE_VISIBILITY explicit basic_string(const allocator_type& __a)
795#if _LIBCPP_STD_VER <= 14
796        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value);
797#else
798        _NOEXCEPT;
799#endif
800
801    basic_string(const basic_string& __str);
802    basic_string(const basic_string& __str, const allocator_type& __a);
803
804#ifndef _LIBCPP_CXX03_LANG
805    _LIBCPP_INLINE_VISIBILITY
806    basic_string(basic_string&& __str)
807#if _LIBCPP_STD_VER <= 14
808        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
809#else
810        _NOEXCEPT;
811#endif
812
813    _LIBCPP_INLINE_VISIBILITY
814    basic_string(basic_string&& __str, const allocator_type& __a);
815#endif  // _LIBCPP_CXX03_LANG
816
817    template <class = _EnableIf<__is_allocator<_Allocator>::value, nullptr_t> >
818    _LIBCPP_INLINE_VISIBILITY
819    basic_string(const _CharT* __s) : __r_(__default_init_tag(), __default_init_tag()) {
820      _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*) detected nullptr");
821      __init(__s, traits_type::length(__s));
822#   if _LIBCPP_DEBUG_LEVEL >= 2
823      __get_db()->__insert_c(this);
824#   endif
825    }
826
827    template <class = _EnableIf<__is_allocator<_Allocator>::value, nullptr_t> >
828        _LIBCPP_INLINE_VISIBILITY
829        basic_string(const _CharT* __s, const _Allocator& __a);
830
831    _LIBCPP_INLINE_VISIBILITY
832    basic_string(const _CharT* __s, size_type __n);
833    _LIBCPP_INLINE_VISIBILITY
834    basic_string(const _CharT* __s, size_type __n, const _Allocator& __a);
835    _LIBCPP_INLINE_VISIBILITY
836    basic_string(size_type __n, _CharT __c);
837
838    template <class = _EnableIf<__is_allocator<_Allocator>::value, nullptr_t> >
839        _LIBCPP_INLINE_VISIBILITY
840        basic_string(size_type __n, _CharT __c, const _Allocator& __a);
841
842    basic_string(const basic_string& __str, size_type __pos, size_type __n,
843                 const _Allocator& __a = _Allocator());
844    _LIBCPP_INLINE_VISIBILITY
845    basic_string(const basic_string& __str, size_type __pos,
846                 const _Allocator& __a = _Allocator());
847
848    template<class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
849        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
850        basic_string(const _Tp& __t, size_type __pos, size_type __n,
851                     const allocator_type& __a = allocator_type());
852
853    template<class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
854                                          !__is_same_uncvref<_Tp, basic_string>::value> >
855        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
856        explicit basic_string(const _Tp& __t);
857
858    template<class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
859        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
860        explicit basic_string(const _Tp& __t, const allocator_type& __a);
861
862    template<class _InputIterator, class = _EnableIf<__is_cpp17_input_iterator<_InputIterator>::value> >
863        _LIBCPP_INLINE_VISIBILITY
864        basic_string(_InputIterator __first, _InputIterator __last);
865    template<class _InputIterator, class = _EnableIf<__is_cpp17_input_iterator<_InputIterator>::value> >
866        _LIBCPP_INLINE_VISIBILITY
867        basic_string(_InputIterator __first, _InputIterator __last, const allocator_type& __a);
868#ifndef _LIBCPP_CXX03_LANG
869    _LIBCPP_INLINE_VISIBILITY
870    basic_string(initializer_list<_CharT> __il);
871    _LIBCPP_INLINE_VISIBILITY
872    basic_string(initializer_list<_CharT> __il, const _Allocator& __a);
873#endif  // _LIBCPP_CXX03_LANG
874
875    inline ~basic_string();
876
877    _LIBCPP_INLINE_VISIBILITY
878    operator __self_view() const _NOEXCEPT { return __self_view(data(), size()); }
879
880    basic_string& operator=(const basic_string& __str);
881
882    template <class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
883    basic_string& operator=(const _Tp& __t)
884        {__self_view __sv = __t; return assign(__sv);}
885
886#ifndef _LIBCPP_CXX03_LANG
887    _LIBCPP_INLINE_VISIBILITY
888    basic_string& operator=(basic_string&& __str)
889        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value));
890     _LIBCPP_INLINE_VISIBILITY
891    basic_string& operator=(initializer_list<value_type> __il) {return assign(__il.begin(), __il.size());}
892#endif
893    _LIBCPP_INLINE_VISIBILITY basic_string& operator=(const value_type* __s) {return assign(__s);}
894    basic_string& operator=(value_type __c);
895
896#if _LIBCPP_DEBUG_LEVEL >= 2
897    _LIBCPP_INLINE_VISIBILITY
898    iterator begin() _NOEXCEPT
899        {return iterator(this, __get_pointer());}
900    _LIBCPP_INLINE_VISIBILITY
901    const_iterator begin() const _NOEXCEPT
902        {return const_iterator(this, __get_pointer());}
903    _LIBCPP_INLINE_VISIBILITY
904    iterator end() _NOEXCEPT
905        {return iterator(this, __get_pointer() + size());}
906    _LIBCPP_INLINE_VISIBILITY
907    const_iterator end() const _NOEXCEPT
908        {return const_iterator(this, __get_pointer() + size());}
909#else
910    _LIBCPP_INLINE_VISIBILITY
911    iterator begin() _NOEXCEPT
912        {return iterator(__get_pointer());}
913    _LIBCPP_INLINE_VISIBILITY
914    const_iterator begin() const _NOEXCEPT
915        {return const_iterator(__get_pointer());}
916    _LIBCPP_INLINE_VISIBILITY
917    iterator end() _NOEXCEPT
918        {return iterator(__get_pointer() + size());}
919    _LIBCPP_INLINE_VISIBILITY
920    const_iterator end() const _NOEXCEPT
921        {return const_iterator(__get_pointer() + size());}
922#endif  // _LIBCPP_DEBUG_LEVEL >= 2
923    _LIBCPP_INLINE_VISIBILITY
924    reverse_iterator rbegin() _NOEXCEPT
925        {return reverse_iterator(end());}
926    _LIBCPP_INLINE_VISIBILITY
927    const_reverse_iterator rbegin() const _NOEXCEPT
928        {return const_reverse_iterator(end());}
929    _LIBCPP_INLINE_VISIBILITY
930    reverse_iterator rend() _NOEXCEPT
931        {return reverse_iterator(begin());}
932    _LIBCPP_INLINE_VISIBILITY
933    const_reverse_iterator rend() const _NOEXCEPT
934        {return const_reverse_iterator(begin());}
935
936    _LIBCPP_INLINE_VISIBILITY
937    const_iterator cbegin() const _NOEXCEPT
938        {return begin();}
939    _LIBCPP_INLINE_VISIBILITY
940    const_iterator cend() const _NOEXCEPT
941        {return end();}
942    _LIBCPP_INLINE_VISIBILITY
943    const_reverse_iterator crbegin() const _NOEXCEPT
944        {return rbegin();}
945    _LIBCPP_INLINE_VISIBILITY
946    const_reverse_iterator crend() const _NOEXCEPT
947        {return rend();}
948
949    _LIBCPP_INLINE_VISIBILITY size_type size() const _NOEXCEPT
950        {return __is_long() ? __get_long_size() : __get_short_size();}
951    _LIBCPP_INLINE_VISIBILITY size_type length() const _NOEXCEPT {return size();}
952    _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT;
953    _LIBCPP_INLINE_VISIBILITY size_type capacity() const _NOEXCEPT
954        {return (__is_long() ? __get_long_cap()
955                             : static_cast<size_type>(__min_cap)) - 1;}
956
957    void resize(size_type __n, value_type __c);
958    _LIBCPP_INLINE_VISIBILITY void resize(size_type __n) {resize(__n, value_type());}
959
960    void reserve(size_type __res_arg);
961    _LIBCPP_INLINE_VISIBILITY void __resize_default_init(size_type __n);
962
963    _LIBCPP_INLINE_VISIBILITY
964    void reserve() _NOEXCEPT {reserve(0);}
965    _LIBCPP_INLINE_VISIBILITY
966    void shrink_to_fit() _NOEXCEPT {reserve();}
967    _LIBCPP_INLINE_VISIBILITY
968    void clear() _NOEXCEPT;
969    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
970    bool empty() const _NOEXCEPT {return size() == 0;}
971
972    _LIBCPP_INLINE_VISIBILITY const_reference operator[](size_type __pos) const _NOEXCEPT;
973    _LIBCPP_INLINE_VISIBILITY reference       operator[](size_type __pos)       _NOEXCEPT;
974
975    const_reference at(size_type __n) const;
976    reference       at(size_type __n);
977
978    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const basic_string& __str) {return append(__str);}
979
980    template <class _Tp>
981    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
982    _EnableIf
983        <
984            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
985            && !__is_same_uncvref<_Tp, basic_string >::value,
986            basic_string&
987        >
988                                            operator+=(const _Tp& __t)            {__self_view __sv = __t; return append(__sv);}
989    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const value_type* __s)     {return append(__s);}
990    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(value_type __c)            {push_back(__c); return *this;}
991#ifndef _LIBCPP_CXX03_LANG
992    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(initializer_list<value_type> __il) {return append(__il);}
993#endif  // _LIBCPP_CXX03_LANG
994
995    _LIBCPP_INLINE_VISIBILITY
996    basic_string& append(const basic_string& __str);
997
998    template <class _Tp>
999    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1000    _EnableIf<
1001            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1002            && !__is_same_uncvref<_Tp, basic_string>::value,
1003            basic_string&
1004        >
1005                  append(const _Tp& __t) { __self_view __sv = __t; return append(__sv.data(), __sv.size()); }
1006    basic_string& append(const basic_string& __str, size_type __pos, size_type __n=npos);
1007
1008    template <class _Tp>
1009    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1010    _EnableIf
1011        <
1012            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1013            && !__is_same_uncvref<_Tp, basic_string>::value,
1014            basic_string&
1015        >
1016                  append(const _Tp& __t, size_type __pos, size_type __n=npos);
1017    basic_string& append(const value_type* __s, size_type __n);
1018    basic_string& append(const value_type* __s);
1019    basic_string& append(size_type __n, value_type __c);
1020
1021    _LIBCPP_INLINE_VISIBILITY
1022    void __append_default_init(size_type __n);
1023
1024    template <class _ForwardIterator>
1025    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1026    basic_string& __append_forward_unsafe(_ForwardIterator, _ForwardIterator);
1027    template<class _InputIterator>
1028    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1029    _EnableIf
1030        <
1031            __is_exactly_cpp17_input_iterator<_InputIterator>::value
1032                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
1033            basic_string&
1034        >
1035    _LIBCPP_INLINE_VISIBILITY
1036    append(_InputIterator __first, _InputIterator __last) {
1037      const basic_string __temp (__first, __last, __alloc());
1038      append(__temp.data(), __temp.size());
1039      return *this;
1040    }
1041    template<class _ForwardIterator>
1042    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1043    _EnableIf
1044        <
1045            __is_cpp17_forward_iterator<_ForwardIterator>::value
1046                && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
1047            basic_string&
1048        >
1049    _LIBCPP_INLINE_VISIBILITY
1050    append(_ForwardIterator __first, _ForwardIterator __last) {
1051      return __append_forward_unsafe(__first, __last);
1052    }
1053
1054#ifndef _LIBCPP_CXX03_LANG
1055    _LIBCPP_INLINE_VISIBILITY
1056    basic_string& append(initializer_list<value_type> __il) {return append(__il.begin(), __il.size());}
1057#endif  // _LIBCPP_CXX03_LANG
1058
1059    void push_back(value_type __c);
1060    _LIBCPP_INLINE_VISIBILITY
1061    void pop_back();
1062    _LIBCPP_INLINE_VISIBILITY reference       front() _NOEXCEPT;
1063    _LIBCPP_INLINE_VISIBILITY const_reference front() const _NOEXCEPT;
1064    _LIBCPP_INLINE_VISIBILITY reference       back() _NOEXCEPT;
1065    _LIBCPP_INLINE_VISIBILITY const_reference back() const _NOEXCEPT;
1066
1067    template <class _Tp>
1068    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1069    _EnableIf
1070        <
1071            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1072            basic_string&
1073        >
1074                 assign(const _Tp & __t) { __self_view __sv = __t; return assign(__sv.data(), __sv.size()); }
1075    _LIBCPP_INLINE_VISIBILITY
1076    basic_string& assign(const basic_string& __str) { return *this = __str; }
1077#ifndef _LIBCPP_CXX03_LANG
1078    _LIBCPP_INLINE_VISIBILITY
1079    basic_string& assign(basic_string&& __str)
1080        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
1081        {*this = _VSTD::move(__str); return *this;}
1082#endif
1083    basic_string& assign(const basic_string& __str, size_type __pos, size_type __n=npos);
1084    template <class _Tp>
1085    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1086    _EnableIf
1087        <
1088            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1089            && !__is_same_uncvref<_Tp, basic_string>::value,
1090            basic_string&
1091        >
1092                  assign(const _Tp & __t, size_type __pos, size_type __n=npos);
1093    basic_string& assign(const value_type* __s, size_type __n);
1094    basic_string& assign(const value_type* __s);
1095    basic_string& assign(size_type __n, value_type __c);
1096    template<class _InputIterator>
1097    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1098    _EnableIf
1099        <
1100           __is_exactly_cpp17_input_iterator<_InputIterator>::value
1101                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
1102            basic_string&
1103        >
1104        assign(_InputIterator __first, _InputIterator __last);
1105    template<class _ForwardIterator>
1106    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1107    _EnableIf
1108        <
1109            __is_cpp17_forward_iterator<_ForwardIterator>::value
1110                 && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
1111            basic_string&
1112        >
1113        assign(_ForwardIterator __first, _ForwardIterator __last);
1114#ifndef _LIBCPP_CXX03_LANG
1115    _LIBCPP_INLINE_VISIBILITY
1116    basic_string& assign(initializer_list<value_type> __il) {return assign(__il.begin(), __il.size());}
1117#endif  // _LIBCPP_CXX03_LANG
1118
1119    _LIBCPP_INLINE_VISIBILITY
1120    basic_string& insert(size_type __pos1, const basic_string& __str);
1121
1122    template <class _Tp>
1123    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1124    _EnableIf
1125        <
1126            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1127            basic_string&
1128        >
1129                 insert(size_type __pos1, const _Tp& __t)
1130    { __self_view __sv = __t; return insert(__pos1, __sv.data(), __sv.size()); }
1131
1132    template <class _Tp>
1133    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1134    _EnableIf
1135        <
1136            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value,
1137            basic_string&
1138        >
1139                  insert(size_type __pos1, const _Tp& __t, size_type __pos2, size_type __n=npos);
1140    basic_string& insert(size_type __pos1, const basic_string& __str, size_type __pos2, size_type __n=npos);
1141    basic_string& insert(size_type __pos, const value_type* __s, size_type __n);
1142    basic_string& insert(size_type __pos, const value_type* __s);
1143    basic_string& insert(size_type __pos, size_type __n, value_type __c);
1144    iterator      insert(const_iterator __pos, value_type __c);
1145    _LIBCPP_INLINE_VISIBILITY
1146    iterator      insert(const_iterator __pos, size_type __n, value_type __c);
1147    template<class _InputIterator>
1148    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1149    _EnableIf
1150        <
1151           __is_exactly_cpp17_input_iterator<_InputIterator>::value
1152                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
1153            iterator
1154        >
1155        insert(const_iterator __pos, _InputIterator __first, _InputIterator __last);
1156    template<class _ForwardIterator>
1157    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1158    _EnableIf
1159        <
1160            __is_cpp17_forward_iterator<_ForwardIterator>::value
1161                 && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
1162            iterator
1163        >
1164        insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last);
1165#ifndef _LIBCPP_CXX03_LANG
1166    _LIBCPP_INLINE_VISIBILITY
1167    iterator insert(const_iterator __pos, initializer_list<value_type> __il)
1168                    {return insert(__pos, __il.begin(), __il.end());}
1169#endif  // _LIBCPP_CXX03_LANG
1170
1171    basic_string& erase(size_type __pos = 0, size_type __n = npos);
1172    _LIBCPP_INLINE_VISIBILITY
1173    iterator      erase(const_iterator __pos);
1174    _LIBCPP_INLINE_VISIBILITY
1175    iterator      erase(const_iterator __first, const_iterator __last);
1176
1177    _LIBCPP_INLINE_VISIBILITY
1178    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str);
1179
1180    template <class _Tp>
1181    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1182    _EnableIf
1183        <
1184            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1185            basic_string&
1186        >
1187                  replace(size_type __pos1, size_type __n1, const _Tp& __t) { __self_view __sv = __t; return replace(__pos1, __n1, __sv.data(), __sv.size()); }
1188    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos);
1189    template <class _Tp>
1190    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1191    _EnableIf
1192        <
1193            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
1194            basic_string&
1195        >
1196                  replace(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos);
1197    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2);
1198    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s);
1199    basic_string& replace(size_type __pos, size_type __n1, size_type __n2, value_type __c);
1200    _LIBCPP_INLINE_VISIBILITY
1201    basic_string& replace(const_iterator __i1, const_iterator __i2, const basic_string& __str);
1202
1203    template <class _Tp>
1204    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1205    _EnableIf
1206        <
1207            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1208            basic_string&
1209        >
1210                  replace(const_iterator __i1, const_iterator __i2, const _Tp& __t) { __self_view __sv = __t; return replace(__i1 - begin(), __i2 - __i1, __sv); }
1211
1212    _LIBCPP_INLINE_VISIBILITY
1213    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n);
1214    _LIBCPP_INLINE_VISIBILITY
1215    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s);
1216    _LIBCPP_INLINE_VISIBILITY
1217    basic_string& replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c);
1218    template<class _InputIterator>
1219    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1220    _EnableIf
1221        <
1222            __is_cpp17_input_iterator<_InputIterator>::value,
1223            basic_string&
1224        >
1225        replace(const_iterator __i1, const_iterator __i2, _InputIterator __j1, _InputIterator __j2);
1226#ifndef _LIBCPP_CXX03_LANG
1227    _LIBCPP_INLINE_VISIBILITY
1228    basic_string& replace(const_iterator __i1, const_iterator __i2, initializer_list<value_type> __il)
1229        {return replace(__i1, __i2, __il.begin(), __il.end());}
1230#endif  // _LIBCPP_CXX03_LANG
1231
1232    size_type copy(value_type* __s, size_type __n, size_type __pos = 0) const;
1233    _LIBCPP_INLINE_VISIBILITY
1234    basic_string substr(size_type __pos = 0, size_type __n = npos) const;
1235
1236    _LIBCPP_INLINE_VISIBILITY
1237    void swap(basic_string& __str)
1238#if _LIBCPP_STD_VER >= 14
1239        _NOEXCEPT;
1240#else
1241        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
1242                    __is_nothrow_swappable<allocator_type>::value);
1243#endif
1244
1245    _LIBCPP_INLINE_VISIBILITY
1246    const value_type* c_str() const _NOEXCEPT {return data();}
1247    _LIBCPP_INLINE_VISIBILITY
1248    const value_type* data() const _NOEXCEPT  {return _VSTD::__to_address(__get_pointer());}
1249#if _LIBCPP_STD_VER > 14 || defined(_LIBCPP_BUILDING_LIBRARY)
1250    _LIBCPP_INLINE_VISIBILITY
1251    value_type* data()             _NOEXCEPT  {return _VSTD::__to_address(__get_pointer());}
1252#endif
1253
1254    _LIBCPP_INLINE_VISIBILITY
1255    allocator_type get_allocator() const _NOEXCEPT {return __alloc();}
1256
1257    _LIBCPP_INLINE_VISIBILITY
1258    size_type find(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1259
1260    template <class _Tp>
1261    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1262    _EnableIf
1263        <
1264            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1265            size_type
1266        >
1267              find(const _Tp& __t, size_type __pos = 0) const;
1268    size_type find(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1269    _LIBCPP_INLINE_VISIBILITY
1270    size_type find(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1271    size_type find(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1272
1273    _LIBCPP_INLINE_VISIBILITY
1274    size_type rfind(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1275
1276    template <class _Tp>
1277    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1278    _EnableIf
1279        <
1280            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1281            size_type
1282        >
1283              rfind(const _Tp& __t, size_type __pos = npos) const;
1284    size_type rfind(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1285    _LIBCPP_INLINE_VISIBILITY
1286    size_type rfind(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1287    size_type rfind(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1288
1289    _LIBCPP_INLINE_VISIBILITY
1290    size_type find_first_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1291
1292    template <class _Tp>
1293    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1294    _EnableIf
1295        <
1296            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1297            size_type
1298        >
1299              find_first_of(const _Tp& __t, size_type __pos = 0) const;
1300    size_type find_first_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1301    _LIBCPP_INLINE_VISIBILITY
1302    size_type find_first_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1303    _LIBCPP_INLINE_VISIBILITY
1304    size_type find_first_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1305
1306    _LIBCPP_INLINE_VISIBILITY
1307    size_type find_last_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1308
1309    template <class _Tp>
1310    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1311    _EnableIf
1312        <
1313            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1314            size_type
1315        >
1316              find_last_of(const _Tp& __t, size_type __pos = npos) const;
1317    size_type find_last_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1318    _LIBCPP_INLINE_VISIBILITY
1319    size_type find_last_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1320    _LIBCPP_INLINE_VISIBILITY
1321    size_type find_last_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1322
1323    _LIBCPP_INLINE_VISIBILITY
1324    size_type find_first_not_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1325
1326    template <class _Tp>
1327    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1328    _EnableIf
1329        <
1330            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1331            size_type
1332        >
1333              find_first_not_of(const _Tp &__t, size_type __pos = 0) const;
1334    size_type find_first_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1335    _LIBCPP_INLINE_VISIBILITY
1336    size_type find_first_not_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1337    _LIBCPP_INLINE_VISIBILITY
1338    size_type find_first_not_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1339
1340    _LIBCPP_INLINE_VISIBILITY
1341    size_type find_last_not_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1342
1343    template <class _Tp>
1344    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1345    _EnableIf
1346        <
1347            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1348            size_type
1349        >
1350              find_last_not_of(const _Tp& __t, size_type __pos = npos) const;
1351    size_type find_last_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1352    _LIBCPP_INLINE_VISIBILITY
1353    size_type find_last_not_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1354    _LIBCPP_INLINE_VISIBILITY
1355    size_type find_last_not_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1356
1357    _LIBCPP_INLINE_VISIBILITY
1358    int compare(const basic_string& __str) const _NOEXCEPT;
1359
1360    template <class _Tp>
1361    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1362    _EnableIf
1363        <
1364            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1365            int
1366        >
1367        compare(const _Tp &__t) const;
1368
1369    template <class _Tp>
1370    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1371    _EnableIf
1372        <
1373            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1374            int
1375        >
1376         compare(size_type __pos1, size_type __n1, const _Tp& __t) const;
1377
1378    _LIBCPP_INLINE_VISIBILITY
1379    int compare(size_type __pos1, size_type __n1, const basic_string& __str) const;
1380    int compare(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos) const;
1381
1382    template <class _Tp>
1383    inline _LIBCPP_INLINE_VISIBILITY
1384        _EnableIf
1385        <
1386            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
1387            int
1388        >
1389        compare(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos) const;
1390    int compare(const value_type* __s) const _NOEXCEPT;
1391    int compare(size_type __pos1, size_type __n1, const value_type* __s) const;
1392    int compare(size_type __pos1, size_type __n1, const value_type* __s, size_type __n2) const;
1393
1394#if _LIBCPP_STD_VER > 17
1395    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1396    bool starts_with(__self_view __sv) const _NOEXCEPT
1397    { return __self_view(data(), size()).starts_with(__sv); }
1398
1399    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1400    bool starts_with(value_type __c) const _NOEXCEPT
1401    { return !empty() && _Traits::eq(front(), __c); }
1402
1403    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1404    bool starts_with(const value_type* __s) const _NOEXCEPT
1405    { return starts_with(__self_view(__s)); }
1406
1407    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1408    bool ends_with(__self_view __sv) const _NOEXCEPT
1409    { return __self_view(data(), size()).ends_with( __sv); }
1410
1411    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1412    bool ends_with(value_type __c) const _NOEXCEPT
1413    { return !empty() && _Traits::eq(back(), __c); }
1414
1415    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1416    bool ends_with(const value_type* __s) const _NOEXCEPT
1417    { return ends_with(__self_view(__s)); }
1418#endif
1419
1420    _LIBCPP_INLINE_VISIBILITY bool __invariants() const;
1421
1422    _LIBCPP_INLINE_VISIBILITY void __clear_and_shrink() _NOEXCEPT;
1423
1424    _LIBCPP_INLINE_VISIBILITY
1425    bool __is_long() const _NOEXCEPT
1426        {return bool(__r_.first().__s.__size_ & __short_mask);}
1427
1428#if _LIBCPP_DEBUG_LEVEL >= 2
1429
1430    bool __dereferenceable(const const_iterator* __i) const;
1431    bool __decrementable(const const_iterator* __i) const;
1432    bool __addable(const const_iterator* __i, ptrdiff_t __n) const;
1433    bool __subscriptable(const const_iterator* __i, ptrdiff_t __n) const;
1434
1435#endif  // _LIBCPP_DEBUG_LEVEL >= 2
1436
1437private:
1438    _LIBCPP_INLINE_VISIBILITY
1439    allocator_type& __alloc() _NOEXCEPT
1440        {return __r_.second();}
1441    _LIBCPP_INLINE_VISIBILITY
1442    const allocator_type& __alloc() const _NOEXCEPT
1443        {return __r_.second();}
1444
1445#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1446
1447    _LIBCPP_INLINE_VISIBILITY
1448    void __set_short_size(size_type __s) _NOEXCEPT
1449#   ifdef _LIBCPP_BIG_ENDIAN
1450        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
1451#   else
1452        {__r_.first().__s.__size_ = (unsigned char)(__s);}
1453#   endif
1454
1455    _LIBCPP_INLINE_VISIBILITY
1456    size_type __get_short_size() const _NOEXCEPT
1457#   ifdef _LIBCPP_BIG_ENDIAN
1458        {return __r_.first().__s.__size_ >> 1;}
1459#   else
1460        {return __r_.first().__s.__size_;}
1461#   endif
1462
1463#else  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1464
1465    _LIBCPP_INLINE_VISIBILITY
1466    void __set_short_size(size_type __s) _NOEXCEPT
1467#   ifdef _LIBCPP_BIG_ENDIAN
1468        {__r_.first().__s.__size_ = (unsigned char)(__s);}
1469#   else
1470        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
1471#   endif
1472
1473    _LIBCPP_INLINE_VISIBILITY
1474    size_type __get_short_size() const _NOEXCEPT
1475#   ifdef _LIBCPP_BIG_ENDIAN
1476        {return __r_.first().__s.__size_;}
1477#   else
1478        {return __r_.first().__s.__size_ >> 1;}
1479#   endif
1480
1481#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1482
1483    _LIBCPP_INLINE_VISIBILITY
1484    void __set_long_size(size_type __s) _NOEXCEPT
1485        {__r_.first().__l.__size_ = __s;}
1486    _LIBCPP_INLINE_VISIBILITY
1487    size_type __get_long_size() const _NOEXCEPT
1488        {return __r_.first().__l.__size_;}
1489    _LIBCPP_INLINE_VISIBILITY
1490    void __set_size(size_type __s) _NOEXCEPT
1491        {if (__is_long()) __set_long_size(__s); else __set_short_size(__s);}
1492
1493    _LIBCPP_INLINE_VISIBILITY
1494    void __set_long_cap(size_type __s) _NOEXCEPT
1495        {__r_.first().__l.__cap_  = __long_mask | __s;}
1496    _LIBCPP_INLINE_VISIBILITY
1497    size_type __get_long_cap() const _NOEXCEPT
1498        {return __r_.first().__l.__cap_ & size_type(~__long_mask);}
1499
1500    _LIBCPP_INLINE_VISIBILITY
1501    void __set_long_pointer(pointer __p) _NOEXCEPT
1502        {__r_.first().__l.__data_ = __p;}
1503    _LIBCPP_INLINE_VISIBILITY
1504    pointer __get_long_pointer() _NOEXCEPT
1505        {return __r_.first().__l.__data_;}
1506    _LIBCPP_INLINE_VISIBILITY
1507    const_pointer __get_long_pointer() const _NOEXCEPT
1508        {return __r_.first().__l.__data_;}
1509    _LIBCPP_INLINE_VISIBILITY
1510    pointer __get_short_pointer() _NOEXCEPT
1511        {return pointer_traits<pointer>::pointer_to(__r_.first().__s.__data_[0]);}
1512    _LIBCPP_INLINE_VISIBILITY
1513    const_pointer __get_short_pointer() const _NOEXCEPT
1514        {return pointer_traits<const_pointer>::pointer_to(__r_.first().__s.__data_[0]);}
1515    _LIBCPP_INLINE_VISIBILITY
1516    pointer __get_pointer() _NOEXCEPT
1517        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
1518    _LIBCPP_INLINE_VISIBILITY
1519    const_pointer __get_pointer() const _NOEXCEPT
1520        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
1521
1522    _LIBCPP_INLINE_VISIBILITY
1523    void __zero() _NOEXCEPT
1524        {
1525            size_type (&__a)[__n_words] = __r_.first().__r.__words;
1526            for (unsigned __i = 0; __i < __n_words; ++__i)
1527                __a[__i] = 0;
1528        }
1529
1530    template <size_type __a> static
1531        _LIBCPP_INLINE_VISIBILITY
1532        size_type __align_it(size_type __s) _NOEXCEPT
1533            {return (__s + (__a-1)) & ~(__a-1);}
1534    enum {__alignment = 16};
1535    static _LIBCPP_INLINE_VISIBILITY
1536    size_type __recommend(size_type __s) _NOEXCEPT
1537        {
1538        if (__s < __min_cap) return static_cast<size_type>(__min_cap) - 1;
1539        size_type __guess = __align_it<sizeof(value_type) < __alignment ?
1540                     __alignment/sizeof(value_type) : 1 > (__s+1) - 1;
1541        if (__guess == __min_cap) ++__guess;
1542        return __guess;
1543        }
1544
1545    inline
1546    void __init(const value_type* __s, size_type __sz, size_type __reserve);
1547    inline
1548    void __init(const value_type* __s, size_type __sz);
1549    inline
1550    void __init(size_type __n, value_type __c);
1551
1552    template <class _InputIterator>
1553    inline
1554    _EnableIf
1555    <
1556        __is_exactly_cpp17_input_iterator<_InputIterator>::value
1557    >
1558    __init(_InputIterator __first, _InputIterator __last);
1559
1560    template <class _ForwardIterator>
1561    inline
1562    _EnableIf
1563    <
1564        __is_cpp17_forward_iterator<_ForwardIterator>::value
1565    >
1566    __init(_ForwardIterator __first, _ForwardIterator __last);
1567
1568    void __grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1569                   size_type __n_copy,  size_type __n_del,     size_type __n_add = 0);
1570    void __grow_by_and_replace(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1571                               size_type __n_copy,  size_type __n_del,
1572                               size_type __n_add, const value_type* __p_new_stuff);
1573
1574    _LIBCPP_INLINE_VISIBILITY
1575    void __erase_to_end(size_type __pos);
1576
1577    _LIBCPP_INLINE_VISIBILITY
1578    void __copy_assign_alloc(const basic_string& __str)
1579        {__copy_assign_alloc(__str, integral_constant<bool,
1580                      __alloc_traits::propagate_on_container_copy_assignment::value>());}
1581
1582    _LIBCPP_INLINE_VISIBILITY
1583    void __copy_assign_alloc(const basic_string& __str, true_type)
1584        {
1585            if (__alloc() == __str.__alloc())
1586                __alloc() = __str.__alloc();
1587            else
1588            {
1589                if (!__str.__is_long())
1590                {
1591                    __clear_and_shrink();
1592                    __alloc() = __str.__alloc();
1593                }
1594                else
1595                {
1596                    allocator_type __a = __str.__alloc();
1597                    pointer __p = __alloc_traits::allocate(__a, __str.__get_long_cap());
1598                    __clear_and_shrink();
1599                    __alloc() = _VSTD::move(__a);
1600                    __set_long_pointer(__p);
1601                    __set_long_cap(__str.__get_long_cap());
1602                    __set_long_size(__str.size());
1603                }
1604            }
1605        }
1606
1607    _LIBCPP_INLINE_VISIBILITY
1608    void __copy_assign_alloc(const basic_string&, false_type) _NOEXCEPT
1609        {}
1610
1611#ifndef _LIBCPP_CXX03_LANG
1612    _LIBCPP_INLINE_VISIBILITY
1613    void __move_assign(basic_string& __str, false_type)
1614        _NOEXCEPT_(__alloc_traits::is_always_equal::value);
1615    _LIBCPP_INLINE_VISIBILITY
1616    void __move_assign(basic_string& __str, true_type)
1617#if _LIBCPP_STD_VER > 14
1618        _NOEXCEPT;
1619#else
1620        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
1621#endif
1622#endif
1623
1624    _LIBCPP_INLINE_VISIBILITY
1625    void
1626    __move_assign_alloc(basic_string& __str)
1627        _NOEXCEPT_(
1628            !__alloc_traits::propagate_on_container_move_assignment::value ||
1629            is_nothrow_move_assignable<allocator_type>::value)
1630    {__move_assign_alloc(__str, integral_constant<bool,
1631                      __alloc_traits::propagate_on_container_move_assignment::value>());}
1632
1633    _LIBCPP_INLINE_VISIBILITY
1634    void __move_assign_alloc(basic_string& __c, true_type)
1635        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
1636        {
1637            __alloc() = _VSTD::move(__c.__alloc());
1638        }
1639
1640    _LIBCPP_INLINE_VISIBILITY
1641    void __move_assign_alloc(basic_string&, false_type)
1642        _NOEXCEPT
1643        {}
1644
1645    _LIBCPP_INLINE_VISIBILITY void __invalidate_all_iterators();
1646    _LIBCPP_INLINE_VISIBILITY void __invalidate_iterators_past(size_type);
1647
1648    friend basic_string operator+<>(const basic_string&, const basic_string&);
1649    friend basic_string operator+<>(const value_type*, const basic_string&);
1650    friend basic_string operator+<>(value_type, const basic_string&);
1651    friend basic_string operator+<>(const basic_string&, const value_type*);
1652    friend basic_string operator+<>(const basic_string&, value_type);
1653};
1654
1655#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
1656template<class _InputIterator,
1657         class _CharT = typename iterator_traits<_InputIterator>::value_type,
1658         class _Allocator = allocator<_CharT>,
1659         class = _EnableIf<__is_cpp17_input_iterator<_InputIterator>::value>,
1660         class = _EnableIf<__is_allocator<_Allocator>::value>
1661         >
1662basic_string(_InputIterator, _InputIterator, _Allocator = _Allocator())
1663  -> basic_string<_CharT, char_traits<_CharT>, _Allocator>;
1664
1665template<class _CharT,
1666         class _Traits,
1667         class _Allocator = allocator<_CharT>,
1668         class = _EnableIf<__is_allocator<_Allocator>::value>
1669         >
1670explicit basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
1671  -> basic_string<_CharT, _Traits, _Allocator>;
1672
1673template<class _CharT,
1674         class _Traits,
1675         class _Allocator = allocator<_CharT>,
1676         class = _EnableIf<__is_allocator<_Allocator>::value>,
1677         class _Sz = typename allocator_traits<_Allocator>::size_type
1678         >
1679basic_string(basic_string_view<_CharT, _Traits>, _Sz, _Sz, const _Allocator& = _Allocator())
1680  -> basic_string<_CharT, _Traits, _Allocator>;
1681#endif
1682
1683template <class _CharT, class _Traits, class _Allocator>
1684inline
1685void
1686basic_string<_CharT, _Traits, _Allocator>::__invalidate_all_iterators()
1687{
1688#if _LIBCPP_DEBUG_LEVEL >= 2
1689    __get_db()->__invalidate_all(this);
1690#endif  // _LIBCPP_DEBUG_LEVEL >= 2
1691}
1692
1693template <class _CharT, class _Traits, class _Allocator>
1694inline
1695void
1696basic_string<_CharT, _Traits, _Allocator>::__invalidate_iterators_past(size_type
1697#if _LIBCPP_DEBUG_LEVEL >= 2
1698                                                                        __pos
1699#endif
1700                                                                      )
1701{
1702#if _LIBCPP_DEBUG_LEVEL >= 2
1703    __c_node* __c = __get_db()->__find_c_and_lock(this);
1704    if (__c)
1705    {
1706        const_pointer __new_last = __get_pointer() + __pos;
1707        for (__i_node** __p = __c->end_; __p != __c->beg_; )
1708        {
1709            --__p;
1710            const_iterator* __i = static_cast<const_iterator*>((*__p)->__i_);
1711            if (__i->base() > __new_last)
1712            {
1713                (*__p)->__c_ = nullptr;
1714                if (--__c->end_ != __p)
1715                    memmove(__p, __p+1, (__c->end_ - __p)*sizeof(__i_node*));
1716            }
1717        }
1718        __get_db()->unlock();
1719    }
1720#endif  // _LIBCPP_DEBUG_LEVEL >= 2
1721}
1722
1723template <class _CharT, class _Traits, class _Allocator>
1724inline
1725basic_string<_CharT, _Traits, _Allocator>::basic_string()
1726    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
1727     : __r_(__default_init_tag(), __default_init_tag())
1728{
1729#if _LIBCPP_DEBUG_LEVEL >= 2
1730    __get_db()->__insert_c(this);
1731#endif
1732    __zero();
1733}
1734
1735template <class _CharT, class _Traits, class _Allocator>
1736inline
1737basic_string<_CharT, _Traits, _Allocator>::basic_string(const allocator_type& __a)
1738#if _LIBCPP_STD_VER <= 14
1739        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value)
1740#else
1741        _NOEXCEPT
1742#endif
1743: __r_(__default_init_tag(), __a)
1744{
1745#if _LIBCPP_DEBUG_LEVEL >= 2
1746    __get_db()->__insert_c(this);
1747#endif
1748    __zero();
1749}
1750
1751template <class _CharT, class _Traits, class _Allocator>
1752void basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s,
1753                                                       size_type __sz,
1754                                                       size_type __reserve)
1755{
1756    if (__reserve > max_size())
1757        this->__throw_length_error();
1758    pointer __p;
1759    if (__reserve < __min_cap)
1760    {
1761        __set_short_size(__sz);
1762        __p = __get_short_pointer();
1763    }
1764    else
1765    {
1766        size_type __cap = __recommend(__reserve);
1767        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1768        __set_long_pointer(__p);
1769        __set_long_cap(__cap+1);
1770        __set_long_size(__sz);
1771    }
1772    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1773    traits_type::assign(__p[__sz], value_type());
1774}
1775
1776template <class _CharT, class _Traits, class _Allocator>
1777void
1778basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s, size_type __sz)
1779{
1780    if (__sz > max_size())
1781        this->__throw_length_error();
1782    pointer __p;
1783    if (__sz < __min_cap)
1784    {
1785        __set_short_size(__sz);
1786        __p = __get_short_pointer();
1787    }
1788    else
1789    {
1790        size_type __cap = __recommend(__sz);
1791        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1792        __set_long_pointer(__p);
1793        __set_long_cap(__cap+1);
1794        __set_long_size(__sz);
1795    }
1796    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1797    traits_type::assign(__p[__sz], value_type());
1798}
1799
1800template <class _CharT, class _Traits, class _Allocator>
1801template <class>
1802basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, const _Allocator& __a)
1803    : __r_(__default_init_tag(), __a)
1804{
1805    _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*, allocator) detected nullptr");
1806    __init(__s, traits_type::length(__s));
1807#if _LIBCPP_DEBUG_LEVEL >= 2
1808    __get_db()->__insert_c(this);
1809#endif
1810}
1811
1812template <class _CharT, class _Traits, class _Allocator>
1813inline
1814basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n)
1815     : __r_(__default_init_tag(), __default_init_tag())
1816{
1817    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n) detected nullptr");
1818    __init(__s, __n);
1819#if _LIBCPP_DEBUG_LEVEL >= 2
1820    __get_db()->__insert_c(this);
1821#endif
1822}
1823
1824template <class _CharT, class _Traits, class _Allocator>
1825inline
1826basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n, const _Allocator& __a)
1827    : __r_(__default_init_tag(), __a)
1828{
1829    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n, allocator) detected nullptr");
1830    __init(__s, __n);
1831#if _LIBCPP_DEBUG_LEVEL >= 2
1832    __get_db()->__insert_c(this);
1833#endif
1834}
1835
1836template <class _CharT, class _Traits, class _Allocator>
1837basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str)
1838    : __r_(__default_init_tag(), __alloc_traits::select_on_container_copy_construction(__str.__alloc()))
1839{
1840    if (!__str.__is_long())
1841        __r_.first().__r = __str.__r_.first().__r;
1842    else
1843        __init(_VSTD::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
1844#if _LIBCPP_DEBUG_LEVEL >= 2
1845    __get_db()->__insert_c(this);
1846#endif
1847}
1848
1849template <class _CharT, class _Traits, class _Allocator>
1850basic_string<_CharT, _Traits, _Allocator>::basic_string(
1851    const basic_string& __str, const allocator_type& __a)
1852    : __r_(__default_init_tag(), __a)
1853{
1854    if (!__str.__is_long())
1855        __r_.first().__r = __str.__r_.first().__r;
1856    else
1857        __init(_VSTD::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
1858#if _LIBCPP_DEBUG_LEVEL >= 2
1859    __get_db()->__insert_c(this);
1860#endif
1861}
1862
1863#ifndef _LIBCPP_CXX03_LANG
1864
1865template <class _CharT, class _Traits, class _Allocator>
1866inline
1867basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str)
1868#if _LIBCPP_STD_VER <= 14
1869        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
1870#else
1871        _NOEXCEPT
1872#endif
1873    : __r_(_VSTD::move(__str.__r_))
1874{
1875    __str.__zero();
1876#if _LIBCPP_DEBUG_LEVEL >= 2
1877    __get_db()->__insert_c(this);
1878    if (__is_long())
1879        __get_db()->swap(this, &__str);
1880#endif
1881}
1882
1883template <class _CharT, class _Traits, class _Allocator>
1884inline
1885basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str, const allocator_type& __a)
1886    : __r_(__default_init_tag(), __a)
1887{
1888    if (__str.__is_long() && __a != __str.__alloc()) // copy, not move
1889        __init(_VSTD::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
1890    else
1891    {
1892        __r_.first().__r = __str.__r_.first().__r;
1893        __str.__zero();
1894    }
1895#if _LIBCPP_DEBUG_LEVEL >= 2
1896    __get_db()->__insert_c(this);
1897    if (__is_long())
1898        __get_db()->swap(this, &__str);
1899#endif
1900}
1901
1902#endif  // _LIBCPP_CXX03_LANG
1903
1904template <class _CharT, class _Traits, class _Allocator>
1905void
1906basic_string<_CharT, _Traits, _Allocator>::__init(size_type __n, value_type __c)
1907{
1908    if (__n > max_size())
1909        this->__throw_length_error();
1910    pointer __p;
1911    if (__n < __min_cap)
1912    {
1913        __set_short_size(__n);
1914        __p = __get_short_pointer();
1915    }
1916    else
1917    {
1918        size_type __cap = __recommend(__n);
1919        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1920        __set_long_pointer(__p);
1921        __set_long_cap(__cap+1);
1922        __set_long_size(__n);
1923    }
1924    traits_type::assign(_VSTD::__to_address(__p), __n, __c);
1925    traits_type::assign(__p[__n], value_type());
1926}
1927
1928template <class _CharT, class _Traits, class _Allocator>
1929inline
1930basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c)
1931     : __r_(__default_init_tag(), __default_init_tag())
1932{
1933    __init(__n, __c);
1934#if _LIBCPP_DEBUG_LEVEL >= 2
1935    __get_db()->__insert_c(this);
1936#endif
1937}
1938
1939template <class _CharT, class _Traits, class _Allocator>
1940template <class>
1941basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c, const _Allocator& __a)
1942    : __r_(__default_init_tag(), __a)
1943{
1944    __init(__n, __c);
1945#if _LIBCPP_DEBUG_LEVEL >= 2
1946    __get_db()->__insert_c(this);
1947#endif
1948}
1949
1950template <class _CharT, class _Traits, class _Allocator>
1951basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str,
1952                                                        size_type __pos, size_type __n,
1953                                                        const _Allocator& __a)
1954    : __r_(__default_init_tag(), __a)
1955{
1956    size_type __str_sz = __str.size();
1957    if (__pos > __str_sz)
1958        this->__throw_out_of_range();
1959    __init(__str.data() + __pos, _VSTD::min(__n, __str_sz - __pos));
1960#if _LIBCPP_DEBUG_LEVEL >= 2
1961    __get_db()->__insert_c(this);
1962#endif
1963}
1964
1965template <class _CharT, class _Traits, class _Allocator>
1966inline
1967basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str, size_type __pos,
1968                                                        const _Allocator& __a)
1969    : __r_(__default_init_tag(), __a)
1970{
1971    size_type __str_sz = __str.size();
1972    if (__pos > __str_sz)
1973        this->__throw_out_of_range();
1974    __init(__str.data() + __pos, __str_sz - __pos);
1975#if _LIBCPP_DEBUG_LEVEL >= 2
1976    __get_db()->__insert_c(this);
1977#endif
1978}
1979
1980template <class _CharT, class _Traits, class _Allocator>
1981template <class _Tp, class>
1982basic_string<_CharT, _Traits, _Allocator>::basic_string(
1983             const _Tp& __t, size_type __pos, size_type __n, const allocator_type& __a)
1984    : __r_(__default_init_tag(), __a)
1985{
1986    __self_view __sv0 = __t;
1987    __self_view __sv = __sv0.substr(__pos, __n);
1988    __init(__sv.data(), __sv.size());
1989#if _LIBCPP_DEBUG_LEVEL >= 2
1990    __get_db()->__insert_c(this);
1991#endif
1992}
1993
1994template <class _CharT, class _Traits, class _Allocator>
1995template <class _Tp, class>
1996basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t)
1997     : __r_(__default_init_tag(), __default_init_tag())
1998{
1999    __self_view __sv = __t;
2000    __init(__sv.data(), __sv.size());
2001#if _LIBCPP_DEBUG_LEVEL >= 2
2002    __get_db()->__insert_c(this);
2003#endif
2004}
2005
2006template <class _CharT, class _Traits, class _Allocator>
2007template <class _Tp, class>
2008basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t, const _Allocator& __a)
2009    : __r_(__default_init_tag(), __a)
2010{
2011    __self_view __sv = __t;
2012    __init(__sv.data(), __sv.size());
2013#if _LIBCPP_DEBUG_LEVEL >= 2
2014    __get_db()->__insert_c(this);
2015#endif
2016}
2017
2018template <class _CharT, class _Traits, class _Allocator>
2019template <class _InputIterator>
2020_EnableIf
2021<
2022    __is_exactly_cpp17_input_iterator<_InputIterator>::value
2023>
2024basic_string<_CharT, _Traits, _Allocator>::__init(_InputIterator __first, _InputIterator __last)
2025{
2026    __zero();
2027#ifndef _LIBCPP_NO_EXCEPTIONS
2028    try
2029    {
2030#endif  // _LIBCPP_NO_EXCEPTIONS
2031    for (; __first != __last; ++__first)
2032        push_back(*__first);
2033#ifndef _LIBCPP_NO_EXCEPTIONS
2034    }
2035    catch (...)
2036    {
2037        if (__is_long())
2038            __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2039        throw;
2040    }
2041#endif  // _LIBCPP_NO_EXCEPTIONS
2042}
2043
2044template <class _CharT, class _Traits, class _Allocator>
2045template <class _ForwardIterator>
2046_EnableIf
2047<
2048    __is_cpp17_forward_iterator<_ForwardIterator>::value
2049>
2050basic_string<_CharT, _Traits, _Allocator>::__init(_ForwardIterator __first, _ForwardIterator __last)
2051{
2052    size_type __sz = static_cast<size_type>(_VSTD::distance(__first, __last));
2053    if (__sz > max_size())
2054        this->__throw_length_error();
2055    pointer __p;
2056    if (__sz < __min_cap)
2057    {
2058        __set_short_size(__sz);
2059        __p = __get_short_pointer();
2060    }
2061    else
2062    {
2063        size_type __cap = __recommend(__sz);
2064        __p = __alloc_traits::allocate(__alloc(), __cap+1);
2065        __set_long_pointer(__p);
2066        __set_long_cap(__cap+1);
2067        __set_long_size(__sz);
2068    }
2069    for (; __first != __last; ++__first, (void) ++__p)
2070        traits_type::assign(*__p, *__first);
2071    traits_type::assign(*__p, value_type());
2072}
2073
2074template <class _CharT, class _Traits, class _Allocator>
2075template<class _InputIterator, class>
2076inline
2077basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last)
2078     : __r_(__default_init_tag(), __default_init_tag())
2079{
2080    __init(__first, __last);
2081#if _LIBCPP_DEBUG_LEVEL >= 2
2082    __get_db()->__insert_c(this);
2083#endif
2084}
2085
2086template <class _CharT, class _Traits, class _Allocator>
2087template<class _InputIterator, class>
2088inline
2089basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last,
2090                                                        const allocator_type& __a)
2091    : __r_(__default_init_tag(), __a)
2092{
2093    __init(__first, __last);
2094#if _LIBCPP_DEBUG_LEVEL >= 2
2095    __get_db()->__insert_c(this);
2096#endif
2097}
2098
2099#ifndef _LIBCPP_CXX03_LANG
2100
2101template <class _CharT, class _Traits, class _Allocator>
2102inline
2103basic_string<_CharT, _Traits, _Allocator>::basic_string(
2104    initializer_list<_CharT> __il)
2105     : __r_(__default_init_tag(), __default_init_tag())
2106{
2107    __init(__il.begin(), __il.end());
2108#if _LIBCPP_DEBUG_LEVEL >= 2
2109    __get_db()->__insert_c(this);
2110#endif
2111}
2112
2113template <class _CharT, class _Traits, class _Allocator>
2114inline
2115
2116basic_string<_CharT, _Traits, _Allocator>::basic_string(
2117    initializer_list<_CharT> __il, const _Allocator& __a)
2118    : __r_(__default_init_tag(), __a)
2119{
2120    __init(__il.begin(), __il.end());
2121#if _LIBCPP_DEBUG_LEVEL >= 2
2122    __get_db()->__insert_c(this);
2123#endif
2124}
2125
2126#endif  // _LIBCPP_CXX03_LANG
2127
2128template <class _CharT, class _Traits, class _Allocator>
2129basic_string<_CharT, _Traits, _Allocator>::~basic_string()
2130{
2131#if _LIBCPP_DEBUG_LEVEL >= 2
2132    __get_db()->__erase_c(this);
2133#endif
2134    if (__is_long())
2135        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2136}
2137
2138template <class _CharT, class _Traits, class _Allocator>
2139void
2140basic_string<_CharT, _Traits, _Allocator>::__grow_by_and_replace
2141    (size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2142     size_type __n_copy,  size_type __n_del,     size_type __n_add, const value_type* __p_new_stuff)
2143{
2144    size_type __ms = max_size();
2145    if (__delta_cap > __ms - __old_cap - 1)
2146        this->__throw_length_error();
2147    pointer __old_p = __get_pointer();
2148    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2149                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2150                          __ms - 1;
2151    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2152    __invalidate_all_iterators();
2153    if (__n_copy != 0)
2154        traits_type::copy(_VSTD::__to_address(__p),
2155                          _VSTD::__to_address(__old_p), __n_copy);
2156    if (__n_add != 0)
2157        traits_type::copy(_VSTD::__to_address(__p) + __n_copy, __p_new_stuff, __n_add);
2158    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2159    if (__sec_cp_sz != 0)
2160        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2161                          _VSTD::__to_address(__old_p) + __n_copy + __n_del, __sec_cp_sz);
2162    if (__old_cap+1 != __min_cap)
2163        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2164    __set_long_pointer(__p);
2165    __set_long_cap(__cap+1);
2166    __old_sz = __n_copy + __n_add + __sec_cp_sz;
2167    __set_long_size(__old_sz);
2168    traits_type::assign(__p[__old_sz], value_type());
2169}
2170
2171template <class _CharT, class _Traits, class _Allocator>
2172void
2173basic_string<_CharT, _Traits, _Allocator>::__grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2174                                                     size_type __n_copy,  size_type __n_del,     size_type __n_add)
2175{
2176    size_type __ms = max_size();
2177    if (__delta_cap > __ms - __old_cap)
2178        this->__throw_length_error();
2179    pointer __old_p = __get_pointer();
2180    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2181                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2182                          __ms - 1;
2183    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2184    __invalidate_all_iterators();
2185    if (__n_copy != 0)
2186        traits_type::copy(_VSTD::__to_address(__p),
2187                          _VSTD::__to_address(__old_p), __n_copy);
2188    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2189    if (__sec_cp_sz != 0)
2190        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2191                          _VSTD::__to_address(__old_p) + __n_copy + __n_del,
2192                          __sec_cp_sz);
2193    if (__old_cap+1 != __min_cap)
2194        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2195    __set_long_pointer(__p);
2196    __set_long_cap(__cap+1);
2197}
2198
2199// assign
2200
2201template <class _CharT, class _Traits, class _Allocator>
2202basic_string<_CharT, _Traits, _Allocator>&
2203basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s, size_type __n)
2204{
2205    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::assign received nullptr");
2206    size_type __cap = capacity();
2207    if (__cap >= __n)
2208    {
2209        value_type* __p = _VSTD::__to_address(__get_pointer());
2210        traits_type::move(__p, __s, __n);
2211        traits_type::assign(__p[__n], value_type());
2212        __set_size(__n);
2213        __invalidate_iterators_past(__n);
2214    }
2215    else
2216    {
2217        size_type __sz = size();
2218        __grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s);
2219    }
2220    return *this;
2221}
2222
2223template <class _CharT, class _Traits, class _Allocator>
2224basic_string<_CharT, _Traits, _Allocator>&
2225basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
2226{
2227    size_type __cap = capacity();
2228    if (__cap < __n)
2229    {
2230        size_type __sz = size();
2231        __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2232    }
2233    else
2234        __invalidate_iterators_past(__n);
2235    value_type* __p = _VSTD::__to_address(__get_pointer());
2236    traits_type::assign(__p, __n, __c);
2237    traits_type::assign(__p[__n], value_type());
2238    __set_size(__n);
2239    return *this;
2240}
2241
2242template <class _CharT, class _Traits, class _Allocator>
2243basic_string<_CharT, _Traits, _Allocator>&
2244basic_string<_CharT, _Traits, _Allocator>::operator=(value_type __c)
2245{
2246    pointer __p;
2247    if (__is_long())
2248    {
2249        __p = __get_long_pointer();
2250        __set_long_size(1);
2251    }
2252    else
2253    {
2254        __p = __get_short_pointer();
2255        __set_short_size(1);
2256    }
2257    traits_type::assign(*__p, __c);
2258    traits_type::assign(*++__p, value_type());
2259    __invalidate_iterators_past(1);
2260    return *this;
2261}
2262
2263template <class _CharT, class _Traits, class _Allocator>
2264basic_string<_CharT, _Traits, _Allocator>&
2265basic_string<_CharT, _Traits, _Allocator>::operator=(const basic_string& __str)
2266{
2267    if (this != &__str)
2268    {
2269        __copy_assign_alloc(__str);
2270        const bool __str_is_long = __str.__is_long(); // Force single branch
2271        if (__is_long() || __str_is_long) {
2272          return assign(__str.data(), __str.size());
2273        }
2274        __r_.first().__r = __str.__r_.first().__r;
2275    }
2276    return *this;
2277}
2278
2279#ifndef _LIBCPP_CXX03_LANG
2280
2281template <class _CharT, class _Traits, class _Allocator>
2282inline
2283void
2284basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, false_type)
2285    _NOEXCEPT_(__alloc_traits::is_always_equal::value)
2286{
2287    if (__alloc() != __str.__alloc())
2288        assign(__str);
2289    else
2290        __move_assign(__str, true_type());
2291}
2292
2293template <class _CharT, class _Traits, class _Allocator>
2294inline
2295void
2296basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, true_type)
2297#if _LIBCPP_STD_VER > 14
2298    _NOEXCEPT
2299#else
2300    _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
2301#endif
2302{
2303  if (__is_long()) {
2304    __alloc_traits::deallocate(__alloc(), __get_long_pointer(),
2305                               __get_long_cap());
2306#if _LIBCPP_STD_VER <= 14
2307    if (!is_nothrow_move_assignable<allocator_type>::value) {
2308      __set_short_size(0);
2309      traits_type::assign(__get_short_pointer()[0], value_type());
2310    }
2311#endif
2312  }
2313  __move_assign_alloc(__str);
2314  __r_.first() = __str.__r_.first();
2315  __str.__set_short_size(0);
2316  traits_type::assign(__str.__get_short_pointer()[0], value_type());
2317}
2318
2319template <class _CharT, class _Traits, class _Allocator>
2320inline
2321basic_string<_CharT, _Traits, _Allocator>&
2322basic_string<_CharT, _Traits, _Allocator>::operator=(basic_string&& __str)
2323    _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
2324{
2325    __move_assign(__str, integral_constant<bool,
2326          __alloc_traits::propagate_on_container_move_assignment::value>());
2327    return *this;
2328}
2329
2330#endif
2331
2332template <class _CharT, class _Traits, class _Allocator>
2333template<class _InputIterator>
2334_EnableIf
2335<
2336     __is_exactly_cpp17_input_iterator <_InputIterator>::value
2337          || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
2338    basic_string<_CharT, _Traits, _Allocator>&
2339>
2340basic_string<_CharT, _Traits, _Allocator>::assign(_InputIterator __first, _InputIterator __last)
2341{
2342    const basic_string __temp(__first, __last, __alloc());
2343    assign(__temp.data(), __temp.size());
2344    return *this;
2345}
2346
2347template <class _CharT, class _Traits, class _Allocator>
2348template<class _ForwardIterator>
2349_EnableIf
2350<
2351    __is_cpp17_forward_iterator<_ForwardIterator>::value
2352         && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
2353    basic_string<_CharT, _Traits, _Allocator>&
2354>
2355basic_string<_CharT, _Traits, _Allocator>::assign(_ForwardIterator __first, _ForwardIterator __last)
2356{
2357    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2358    size_type __cap = capacity();
2359    if (__cap < __n)
2360    {
2361        size_type __sz = size();
2362        __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2363    }
2364    else
2365        __invalidate_iterators_past(__n);
2366    pointer __p = __get_pointer();
2367    for (; __first != __last; ++__first, ++__p)
2368        traits_type::assign(*__p, *__first);
2369    traits_type::assign(*__p, value_type());
2370    __set_size(__n);
2371    return *this;
2372}
2373
2374template <class _CharT, class _Traits, class _Allocator>
2375basic_string<_CharT, _Traits, _Allocator>&
2376basic_string<_CharT, _Traits, _Allocator>::assign(const basic_string& __str, size_type __pos, size_type __n)
2377{
2378    size_type __sz = __str.size();
2379    if (__pos > __sz)
2380        this->__throw_out_of_range();
2381    return assign(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2382}
2383
2384template <class _CharT, class _Traits, class _Allocator>
2385template <class _Tp>
2386_EnableIf
2387<
2388    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
2389    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2390    basic_string<_CharT, _Traits, _Allocator>&
2391>
2392basic_string<_CharT, _Traits, _Allocator>::assign(const _Tp & __t, size_type __pos, size_type __n)
2393{
2394    __self_view __sv = __t;
2395    size_type __sz = __sv.size();
2396    if (__pos > __sz)
2397        this->__throw_out_of_range();
2398    return assign(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2399}
2400
2401
2402template <class _CharT, class _Traits, class _Allocator>
2403basic_string<_CharT, _Traits, _Allocator>&
2404basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s)
2405{
2406    _LIBCPP_ASSERT(__s != nullptr, "string::assign received nullptr");
2407    return assign(__s, traits_type::length(__s));
2408}
2409
2410// append
2411
2412template <class _CharT, class _Traits, class _Allocator>
2413basic_string<_CharT, _Traits, _Allocator>&
2414basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s, size_type __n)
2415{
2416    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::append received nullptr");
2417    size_type __cap = capacity();
2418    size_type __sz = size();
2419    if (__cap - __sz >= __n)
2420    {
2421        if (__n)
2422        {
2423            value_type* __p = _VSTD::__to_address(__get_pointer());
2424            traits_type::copy(__p + __sz, __s, __n);
2425            __sz += __n;
2426            __set_size(__sz);
2427            traits_type::assign(__p[__sz], value_type());
2428        }
2429    }
2430    else
2431        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __sz, 0, __n, __s);
2432    return *this;
2433}
2434
2435template <class _CharT, class _Traits, class _Allocator>
2436basic_string<_CharT, _Traits, _Allocator>&
2437basic_string<_CharT, _Traits, _Allocator>::append(size_type __n, value_type __c)
2438{
2439    if (__n)
2440    {
2441        size_type __cap = capacity();
2442        size_type __sz = size();
2443        if (__cap - __sz < __n)
2444            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2445        pointer __p = __get_pointer();
2446        traits_type::assign(_VSTD::__to_address(__p) + __sz, __n, __c);
2447        __sz += __n;
2448        __set_size(__sz);
2449        traits_type::assign(__p[__sz], value_type());
2450    }
2451    return *this;
2452}
2453
2454template <class _CharT, class _Traits, class _Allocator>
2455inline void
2456basic_string<_CharT, _Traits, _Allocator>::__append_default_init(size_type __n)
2457{
2458    if (__n)
2459    {
2460        size_type __cap = capacity();
2461        size_type __sz = size();
2462        if (__cap - __sz < __n)
2463            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2464        pointer __p = __get_pointer();
2465        __sz += __n;
2466        __set_size(__sz);
2467        traits_type::assign(__p[__sz], value_type());
2468    }
2469}
2470
2471template <class _CharT, class _Traits, class _Allocator>
2472void
2473basic_string<_CharT, _Traits, _Allocator>::push_back(value_type __c)
2474{
2475    bool __is_short = !__is_long();
2476    size_type __cap;
2477    size_type __sz;
2478    if (__is_short)
2479    {
2480        __cap = __min_cap - 1;
2481        __sz = __get_short_size();
2482    }
2483    else
2484    {
2485        __cap = __get_long_cap() - 1;
2486        __sz = __get_long_size();
2487    }
2488    if (__sz == __cap)
2489    {
2490        __grow_by(__cap, 1, __sz, __sz, 0);
2491        __is_short = !__is_long();
2492    }
2493    pointer __p;
2494    if (__is_short)
2495    {
2496        __p = __get_short_pointer() + __sz;
2497        __set_short_size(__sz+1);
2498    }
2499    else
2500    {
2501        __p = __get_long_pointer() + __sz;
2502        __set_long_size(__sz+1);
2503    }
2504    traits_type::assign(*__p, __c);
2505    traits_type::assign(*++__p, value_type());
2506}
2507
2508template <class _Tp>
2509bool __ptr_in_range (const _Tp* __p, const _Tp* __first, const _Tp* __last)
2510{
2511    return __first <= __p && __p < __last;
2512}
2513
2514template <class _Tp1, class _Tp2>
2515bool __ptr_in_range (const _Tp1*, const _Tp2*, const _Tp2*)
2516{
2517    return false;
2518}
2519
2520template <class _CharT, class _Traits, class _Allocator>
2521template<class _ForwardIterator>
2522basic_string<_CharT, _Traits, _Allocator>&
2523basic_string<_CharT, _Traits, _Allocator>::__append_forward_unsafe(
2524    _ForwardIterator __first, _ForwardIterator __last)
2525{
2526    static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value,
2527                  "function requires a ForwardIterator");
2528    size_type __sz = size();
2529    size_type __cap = capacity();
2530    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2531    if (__n)
2532    {
2533        typedef typename iterator_traits<_ForwardIterator>::reference _CharRef;
2534        _CharRef __tmp_ref = *__first;
2535        if (__ptr_in_range(_VSTD::addressof(__tmp_ref), data(), data() + size()))
2536        {
2537            const basic_string __temp (__first, __last, __alloc());
2538            append(__temp.data(), __temp.size());
2539        }
2540        else
2541        {
2542            if (__cap - __sz < __n)
2543                __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2544            pointer __p = __get_pointer() + __sz;
2545            for (; __first != __last; ++__p, ++__first)
2546                traits_type::assign(*__p, *__first);
2547            traits_type::assign(*__p, value_type());
2548            __set_size(__sz + __n);
2549        }
2550    }
2551    return *this;
2552}
2553
2554template <class _CharT, class _Traits, class _Allocator>
2555inline
2556basic_string<_CharT, _Traits, _Allocator>&
2557basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str)
2558{
2559    return append(__str.data(), __str.size());
2560}
2561
2562template <class _CharT, class _Traits, class _Allocator>
2563basic_string<_CharT, _Traits, _Allocator>&
2564basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str, size_type __pos, size_type __n)
2565{
2566    size_type __sz = __str.size();
2567    if (__pos > __sz)
2568        this->__throw_out_of_range();
2569    return append(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2570}
2571
2572template <class _CharT, class _Traits, class _Allocator>
2573template <class _Tp>
2574    _EnableIf
2575    <
2576        __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2577        basic_string<_CharT, _Traits, _Allocator>&
2578    >
2579basic_string<_CharT, _Traits, _Allocator>::append(const _Tp & __t, size_type __pos, size_type __n)
2580{
2581    __self_view __sv = __t;
2582    size_type __sz = __sv.size();
2583    if (__pos > __sz)
2584        this->__throw_out_of_range();
2585    return append(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2586}
2587
2588template <class _CharT, class _Traits, class _Allocator>
2589basic_string<_CharT, _Traits, _Allocator>&
2590basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s)
2591{
2592    _LIBCPP_ASSERT(__s != nullptr, "string::append received nullptr");
2593    return append(__s, traits_type::length(__s));
2594}
2595
2596// insert
2597
2598template <class _CharT, class _Traits, class _Allocator>
2599basic_string<_CharT, _Traits, _Allocator>&
2600basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s, size_type __n)
2601{
2602    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::insert received nullptr");
2603    size_type __sz = size();
2604    if (__pos > __sz)
2605        this->__throw_out_of_range();
2606    size_type __cap = capacity();
2607    if (__cap - __sz >= __n)
2608    {
2609        if (__n)
2610        {
2611            value_type* __p = _VSTD::__to_address(__get_pointer());
2612            size_type __n_move = __sz - __pos;
2613            if (__n_move != 0)
2614            {
2615                if (__p + __pos <= __s && __s < __p + __sz)
2616                    __s += __n;
2617                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2618            }
2619            traits_type::move(__p + __pos, __s, __n);
2620            __sz += __n;
2621            __set_size(__sz);
2622            traits_type::assign(__p[__sz], value_type());
2623        }
2624    }
2625    else
2626        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __pos, 0, __n, __s);
2627    return *this;
2628}
2629
2630template <class _CharT, class _Traits, class _Allocator>
2631basic_string<_CharT, _Traits, _Allocator>&
2632basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, size_type __n, value_type __c)
2633{
2634    size_type __sz = size();
2635    if (__pos > __sz)
2636        this->__throw_out_of_range();
2637    if (__n)
2638    {
2639        size_type __cap = capacity();
2640        value_type* __p;
2641        if (__cap - __sz >= __n)
2642        {
2643            __p = _VSTD::__to_address(__get_pointer());
2644            size_type __n_move = __sz - __pos;
2645            if (__n_move != 0)
2646                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2647        }
2648        else
2649        {
2650            __grow_by(__cap, __sz + __n - __cap, __sz, __pos, 0, __n);
2651            __p = _VSTD::__to_address(__get_long_pointer());
2652        }
2653        traits_type::assign(__p + __pos, __n, __c);
2654        __sz += __n;
2655        __set_size(__sz);
2656        traits_type::assign(__p[__sz], value_type());
2657    }
2658    return *this;
2659}
2660
2661template <class _CharT, class _Traits, class _Allocator>
2662template<class _InputIterator>
2663_EnableIf
2664<
2665   __is_exactly_cpp17_input_iterator<_InputIterator>::value
2666        || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
2667   typename basic_string<_CharT, _Traits, _Allocator>::iterator
2668>
2669basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _InputIterator __first, _InputIterator __last)
2670{
2671#if _LIBCPP_DEBUG_LEVEL >= 2
2672    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2673        "string::insert(iterator, range) called with an iterator not"
2674        " referring to this string");
2675#endif
2676    const basic_string __temp(__first, __last, __alloc());
2677    return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2678}
2679
2680template <class _CharT, class _Traits, class _Allocator>
2681template<class _ForwardIterator>
2682_EnableIf
2683<
2684    __is_cpp17_forward_iterator<_ForwardIterator>::value
2685        && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
2686    typename basic_string<_CharT, _Traits, _Allocator>::iterator
2687>
2688basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last)
2689{
2690#if _LIBCPP_DEBUG_LEVEL >= 2
2691    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2692        "string::insert(iterator, range) called with an iterator not"
2693        " referring to this string");
2694#endif
2695    size_type __ip = static_cast<size_type>(__pos - begin());
2696    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2697    if (__n)
2698    {
2699        typedef typename iterator_traits<_ForwardIterator>::reference _CharRef;
2700        _CharRef __tmp_char = *__first;
2701        if (__ptr_in_range(_VSTD::addressof(__tmp_char), data(), data() + size()))
2702        {
2703            const basic_string __temp(__first, __last, __alloc());
2704            return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2705        }
2706
2707        size_type __sz = size();
2708        size_type __cap = capacity();
2709        value_type* __p;
2710        if (__cap - __sz >= __n)
2711        {
2712            __p = _VSTD::__to_address(__get_pointer());
2713            size_type __n_move = __sz - __ip;
2714            if (__n_move != 0)
2715                traits_type::move(__p + __ip + __n, __p + __ip, __n_move);
2716        }
2717        else
2718        {
2719            __grow_by(__cap, __sz + __n - __cap, __sz, __ip, 0, __n);
2720            __p = _VSTD::__to_address(__get_long_pointer());
2721        }
2722        __sz += __n;
2723        __set_size(__sz);
2724        traits_type::assign(__p[__sz], value_type());
2725        for (__p += __ip; __first != __last; ++__p, ++__first)
2726            traits_type::assign(*__p, *__first);
2727    }
2728    return begin() + __ip;
2729}
2730
2731template <class _CharT, class _Traits, class _Allocator>
2732inline
2733basic_string<_CharT, _Traits, _Allocator>&
2734basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str)
2735{
2736    return insert(__pos1, __str.data(), __str.size());
2737}
2738
2739template <class _CharT, class _Traits, class _Allocator>
2740basic_string<_CharT, _Traits, _Allocator>&
2741basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str,
2742                                                  size_type __pos2, size_type __n)
2743{
2744    size_type __str_sz = __str.size();
2745    if (__pos2 > __str_sz)
2746        this->__throw_out_of_range();
2747    return insert(__pos1, __str.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2748}
2749
2750template <class _CharT, class _Traits, class _Allocator>
2751template <class _Tp>
2752_EnableIf
2753<
2754    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2755    basic_string<_CharT, _Traits, _Allocator>&
2756>
2757basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const _Tp& __t,
2758                                                  size_type __pos2, size_type __n)
2759{
2760    __self_view __sv = __t;
2761    size_type __str_sz = __sv.size();
2762    if (__pos2 > __str_sz)
2763        this->__throw_out_of_range();
2764    return insert(__pos1, __sv.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2765}
2766
2767template <class _CharT, class _Traits, class _Allocator>
2768basic_string<_CharT, _Traits, _Allocator>&
2769basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s)
2770{
2771    _LIBCPP_ASSERT(__s != nullptr, "string::insert received nullptr");
2772    return insert(__pos, __s, traits_type::length(__s));
2773}
2774
2775template <class _CharT, class _Traits, class _Allocator>
2776typename basic_string<_CharT, _Traits, _Allocator>::iterator
2777basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, value_type __c)
2778{
2779    size_type __ip = static_cast<size_type>(__pos - begin());
2780    size_type __sz = size();
2781    size_type __cap = capacity();
2782    value_type* __p;
2783    if (__cap == __sz)
2784    {
2785        __grow_by(__cap, 1, __sz, __ip, 0, 1);
2786        __p = _VSTD::__to_address(__get_long_pointer());
2787    }
2788    else
2789    {
2790        __p = _VSTD::__to_address(__get_pointer());
2791        size_type __n_move = __sz - __ip;
2792        if (__n_move != 0)
2793            traits_type::move(__p + __ip + 1, __p + __ip, __n_move);
2794    }
2795    traits_type::assign(__p[__ip], __c);
2796    traits_type::assign(__p[++__sz], value_type());
2797    __set_size(__sz);
2798    return begin() + static_cast<difference_type>(__ip);
2799}
2800
2801template <class _CharT, class _Traits, class _Allocator>
2802inline
2803typename basic_string<_CharT, _Traits, _Allocator>::iterator
2804basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, size_type __n, value_type __c)
2805{
2806#if _LIBCPP_DEBUG_LEVEL >= 2
2807    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2808        "string::insert(iterator, n, value) called with an iterator not"
2809        " referring to this string");
2810#endif
2811    difference_type __p = __pos - begin();
2812    insert(static_cast<size_type>(__p), __n, __c);
2813    return begin() + __p;
2814}
2815
2816// replace
2817
2818template <class _CharT, class _Traits, class _Allocator>
2819basic_string<_CharT, _Traits, _Allocator>&
2820basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2)
2821    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
2822{
2823    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::replace received nullptr");
2824    size_type __sz = size();
2825    if (__pos > __sz)
2826        this->__throw_out_of_range();
2827    __n1 = _VSTD::min(__n1, __sz - __pos);
2828    size_type __cap = capacity();
2829    if (__cap - __sz + __n1 >= __n2)
2830    {
2831        value_type* __p = _VSTD::__to_address(__get_pointer());
2832        if (__n1 != __n2)
2833        {
2834            size_type __n_move = __sz - __pos - __n1;
2835            if (__n_move != 0)
2836            {
2837                if (__n1 > __n2)
2838                {
2839                    traits_type::move(__p + __pos, __s, __n2);
2840                    traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
2841                    goto __finish;
2842                }
2843                if (__p + __pos < __s && __s < __p + __sz)
2844                {
2845                    if (__p + __pos + __n1 <= __s)
2846                        __s += __n2 - __n1;
2847                    else // __p + __pos < __s < __p + __pos + __n1
2848                    {
2849                        traits_type::move(__p + __pos, __s, __n1);
2850                        __pos += __n1;
2851                        __s += __n2;
2852                        __n2 -= __n1;
2853                        __n1 = 0;
2854                    }
2855                }
2856                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
2857            }
2858        }
2859        traits_type::move(__p + __pos, __s, __n2);
2860__finish:
2861// __sz += __n2 - __n1; in this and the below function below can cause unsigned integer overflow,
2862// but this is a safe operation, so we disable the check.
2863        __sz += __n2 - __n1;
2864        __set_size(__sz);
2865        __invalidate_iterators_past(__sz);
2866        traits_type::assign(__p[__sz], value_type());
2867    }
2868    else
2869        __grow_by_and_replace(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2, __s);
2870    return *this;
2871}
2872
2873template <class _CharT, class _Traits, class _Allocator>
2874basic_string<_CharT, _Traits, _Allocator>&
2875basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, size_type __n2, value_type __c)
2876    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
2877{
2878    size_type __sz = size();
2879    if (__pos > __sz)
2880        this->__throw_out_of_range();
2881    __n1 = _VSTD::min(__n1, __sz - __pos);
2882    size_type __cap = capacity();
2883    value_type* __p;
2884    if (__cap - __sz + __n1 >= __n2)
2885    {
2886        __p = _VSTD::__to_address(__get_pointer());
2887        if (__n1 != __n2)
2888        {
2889            size_type __n_move = __sz - __pos - __n1;
2890            if (__n_move != 0)
2891                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
2892        }
2893    }
2894    else
2895    {
2896        __grow_by(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2);
2897        __p = _VSTD::__to_address(__get_long_pointer());
2898    }
2899    traits_type::assign(__p + __pos, __n2, __c);
2900    __sz += __n2 - __n1;
2901    __set_size(__sz);
2902    __invalidate_iterators_past(__sz);
2903    traits_type::assign(__p[__sz], value_type());
2904    return *this;
2905}
2906
2907template <class _CharT, class _Traits, class _Allocator>
2908template<class _InputIterator>
2909_EnableIf
2910<
2911    __is_cpp17_input_iterator<_InputIterator>::value,
2912    basic_string<_CharT, _Traits, _Allocator>&
2913>
2914basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2,
2915                                                   _InputIterator __j1, _InputIterator __j2)
2916{
2917    const basic_string __temp(__j1, __j2, __alloc());
2918    return this->replace(__i1, __i2, __temp);
2919}
2920
2921template <class _CharT, class _Traits, class _Allocator>
2922inline
2923basic_string<_CharT, _Traits, _Allocator>&
2924basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str)
2925{
2926    return replace(__pos1, __n1, __str.data(), __str.size());
2927}
2928
2929template <class _CharT, class _Traits, class _Allocator>
2930basic_string<_CharT, _Traits, _Allocator>&
2931basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str,
2932                                                   size_type __pos2, size_type __n2)
2933{
2934    size_type __str_sz = __str.size();
2935    if (__pos2 > __str_sz)
2936        this->__throw_out_of_range();
2937    return replace(__pos1, __n1, __str.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
2938}
2939
2940template <class _CharT, class _Traits, class _Allocator>
2941template <class _Tp>
2942_EnableIf
2943<
2944    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2945    basic_string<_CharT, _Traits, _Allocator>&
2946>
2947basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const _Tp& __t,
2948                                                   size_type __pos2, size_type __n2)
2949{
2950    __self_view __sv = __t;
2951    size_type __str_sz = __sv.size();
2952    if (__pos2 > __str_sz)
2953        this->__throw_out_of_range();
2954    return replace(__pos1, __n1, __sv.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
2955}
2956
2957template <class _CharT, class _Traits, class _Allocator>
2958basic_string<_CharT, _Traits, _Allocator>&
2959basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s)
2960{
2961    _LIBCPP_ASSERT(__s != nullptr, "string::replace received nullptr");
2962    return replace(__pos, __n1, __s, traits_type::length(__s));
2963}
2964
2965template <class _CharT, class _Traits, class _Allocator>
2966inline
2967basic_string<_CharT, _Traits, _Allocator>&
2968basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const basic_string& __str)
2969{
2970    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1),
2971                   __str.data(), __str.size());
2972}
2973
2974template <class _CharT, class _Traits, class _Allocator>
2975inline
2976basic_string<_CharT, _Traits, _Allocator>&
2977basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n)
2978{
2979    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s, __n);
2980}
2981
2982template <class _CharT, class _Traits, class _Allocator>
2983inline
2984basic_string<_CharT, _Traits, _Allocator>&
2985basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s)
2986{
2987    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s);
2988}
2989
2990template <class _CharT, class _Traits, class _Allocator>
2991inline
2992basic_string<_CharT, _Traits, _Allocator>&
2993basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c)
2994{
2995    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __n, __c);
2996}
2997
2998// erase
2999
3000template <class _CharT, class _Traits, class _Allocator>
3001basic_string<_CharT, _Traits, _Allocator>&
3002basic_string<_CharT, _Traits, _Allocator>::erase(size_type __pos, size_type __n)
3003{
3004    size_type __sz = size();
3005    if (__pos > __sz)
3006        this->__throw_out_of_range();
3007    if (__n)
3008    {
3009        value_type* __p = _VSTD::__to_address(__get_pointer());
3010        __n = _VSTD::min(__n, __sz - __pos);
3011        size_type __n_move = __sz - __pos - __n;
3012        if (__n_move != 0)
3013            traits_type::move(__p + __pos, __p + __pos + __n, __n_move);
3014        __sz -= __n;
3015        __set_size(__sz);
3016        __invalidate_iterators_past(__sz);
3017        traits_type::assign(__p[__sz], value_type());
3018    }
3019    return *this;
3020}
3021
3022template <class _CharT, class _Traits, class _Allocator>
3023inline
3024typename basic_string<_CharT, _Traits, _Allocator>::iterator
3025basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __pos)
3026{
3027#if _LIBCPP_DEBUG_LEVEL >= 2
3028    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
3029        "string::erase(iterator) called with an iterator not"
3030        " referring to this string");
3031#endif
3032    _LIBCPP_ASSERT(__pos != end(),
3033        "string::erase(iterator) called with a non-dereferenceable iterator");
3034    iterator __b = begin();
3035    size_type __r = static_cast<size_type>(__pos - __b);
3036    erase(__r, 1);
3037    return __b + static_cast<difference_type>(__r);
3038}
3039
3040template <class _CharT, class _Traits, class _Allocator>
3041inline
3042typename basic_string<_CharT, _Traits, _Allocator>::iterator
3043basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __first, const_iterator __last)
3044{
3045#if _LIBCPP_DEBUG_LEVEL >= 2
3046    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__first) == this,
3047        "string::erase(iterator,  iterator) called with an iterator not"
3048        " referring to this string");
3049#endif
3050    _LIBCPP_ASSERT(__first <= __last, "string::erase(first, last) called with invalid range");
3051    iterator __b = begin();
3052    size_type __r = static_cast<size_type>(__first - __b);
3053    erase(__r, static_cast<size_type>(__last - __first));
3054    return __b + static_cast<difference_type>(__r);
3055}
3056
3057template <class _CharT, class _Traits, class _Allocator>
3058inline
3059void
3060basic_string<_CharT, _Traits, _Allocator>::pop_back()
3061{
3062    _LIBCPP_ASSERT(!empty(), "string::pop_back(): string is already empty");
3063    size_type __sz;
3064    if (__is_long())
3065    {
3066        __sz = __get_long_size() - 1;
3067        __set_long_size(__sz);
3068        traits_type::assign(*(__get_long_pointer() + __sz), value_type());
3069    }
3070    else
3071    {
3072        __sz = __get_short_size() - 1;
3073        __set_short_size(__sz);
3074        traits_type::assign(*(__get_short_pointer() + __sz), value_type());
3075    }
3076    __invalidate_iterators_past(__sz);
3077}
3078
3079template <class _CharT, class _Traits, class _Allocator>
3080inline
3081void
3082basic_string<_CharT, _Traits, _Allocator>::clear() _NOEXCEPT
3083{
3084    __invalidate_all_iterators();
3085    if (__is_long())
3086    {
3087        traits_type::assign(*__get_long_pointer(), value_type());
3088        __set_long_size(0);
3089    }
3090    else
3091    {
3092        traits_type::assign(*__get_short_pointer(), value_type());
3093        __set_short_size(0);
3094    }
3095}
3096
3097template <class _CharT, class _Traits, class _Allocator>
3098inline
3099void
3100basic_string<_CharT, _Traits, _Allocator>::__erase_to_end(size_type __pos)
3101{
3102    if (__is_long())
3103    {
3104        traits_type::assign(*(__get_long_pointer() + __pos), value_type());
3105        __set_long_size(__pos);
3106    }
3107    else
3108    {
3109        traits_type::assign(*(__get_short_pointer() + __pos), value_type());
3110        __set_short_size(__pos);
3111    }
3112    __invalidate_iterators_past(__pos);
3113}
3114
3115template <class _CharT, class _Traits, class _Allocator>
3116void
3117basic_string<_CharT, _Traits, _Allocator>::resize(size_type __n, value_type __c)
3118{
3119    size_type __sz = size();
3120    if (__n > __sz)
3121        append(__n - __sz, __c);
3122    else
3123        __erase_to_end(__n);
3124}
3125
3126template <class _CharT, class _Traits, class _Allocator>
3127inline void
3128basic_string<_CharT, _Traits, _Allocator>::__resize_default_init(size_type __n)
3129{
3130    size_type __sz = size();
3131    if (__n > __sz) {
3132       __append_default_init(__n - __sz);
3133    } else
3134        __erase_to_end(__n);
3135}
3136
3137template <class _CharT, class _Traits, class _Allocator>
3138inline
3139typename basic_string<_CharT, _Traits, _Allocator>::size_type
3140basic_string<_CharT, _Traits, _Allocator>::max_size() const _NOEXCEPT
3141{
3142    size_type __m = __alloc_traits::max_size(__alloc());
3143#ifdef _LIBCPP_BIG_ENDIAN
3144    return (__m <= ~__long_mask ? __m : __m/2) - __alignment;
3145#else
3146    return __m - __alignment;
3147#endif
3148}
3149
3150template <class _CharT, class _Traits, class _Allocator>
3151void
3152basic_string<_CharT, _Traits, _Allocator>::reserve(size_type __res_arg)
3153{
3154    if (__res_arg > max_size())
3155        this->__throw_length_error();
3156    size_type __cap = capacity();
3157    size_type __sz = size();
3158    __res_arg = _VSTD::max(__res_arg, __sz);
3159    __res_arg = __recommend(__res_arg);
3160    if (__res_arg != __cap)
3161    {
3162        pointer __new_data, __p;
3163        bool __was_long, __now_long;
3164        if (__res_arg == __min_cap - 1)
3165        {
3166            __was_long = true;
3167            __now_long = false;
3168            __new_data = __get_short_pointer();
3169            __p = __get_long_pointer();
3170        }
3171        else
3172        {
3173            if (__res_arg > __cap)
3174                __new_data = __alloc_traits::allocate(__alloc(), __res_arg+1);
3175            else
3176            {
3177            #ifndef _LIBCPP_NO_EXCEPTIONS
3178                try
3179                {
3180            #endif  // _LIBCPP_NO_EXCEPTIONS
3181                    __new_data = __alloc_traits::allocate(__alloc(), __res_arg+1);
3182            #ifndef _LIBCPP_NO_EXCEPTIONS
3183                }
3184                catch (...)
3185                {
3186                    return;
3187                }
3188            #else  // _LIBCPP_NO_EXCEPTIONS
3189                if (__new_data == nullptr)
3190                    return;
3191            #endif  // _LIBCPP_NO_EXCEPTIONS
3192            }
3193            __now_long = true;
3194            __was_long = __is_long();
3195            __p = __get_pointer();
3196        }
3197        traits_type::copy(_VSTD::__to_address(__new_data),
3198                          _VSTD::__to_address(__p), size()+1);
3199        if (__was_long)
3200            __alloc_traits::deallocate(__alloc(), __p, __cap+1);
3201        if (__now_long)
3202        {
3203            __set_long_cap(__res_arg+1);
3204            __set_long_size(__sz);
3205            __set_long_pointer(__new_data);
3206        }
3207        else
3208            __set_short_size(__sz);
3209        __invalidate_all_iterators();
3210    }
3211}
3212
3213template <class _CharT, class _Traits, class _Allocator>
3214inline
3215typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3216basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) const _NOEXCEPT
3217{
3218    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3219    return *(data() + __pos);
3220}
3221
3222template <class _CharT, class _Traits, class _Allocator>
3223inline
3224typename basic_string<_CharT, _Traits, _Allocator>::reference
3225basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) _NOEXCEPT
3226{
3227    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3228    return *(__get_pointer() + __pos);
3229}
3230
3231template <class _CharT, class _Traits, class _Allocator>
3232typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3233basic_string<_CharT, _Traits, _Allocator>::at(size_type __n) const
3234{
3235    if (__n >= size())
3236        this->__throw_out_of_range();
3237    return (*this)[__n];
3238}
3239
3240template <class _CharT, class _Traits, class _Allocator>
3241typename basic_string<_CharT, _Traits, _Allocator>::reference
3242basic_string<_CharT, _Traits, _Allocator>::at(size_type __n)
3243{
3244    if (__n >= size())
3245        this->__throw_out_of_range();
3246    return (*this)[__n];
3247}
3248
3249template <class _CharT, class _Traits, class _Allocator>
3250inline
3251typename basic_string<_CharT, _Traits, _Allocator>::reference
3252basic_string<_CharT, _Traits, _Allocator>::front() _NOEXCEPT
3253{
3254    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3255    return *__get_pointer();
3256}
3257
3258template <class _CharT, class _Traits, class _Allocator>
3259inline
3260typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3261basic_string<_CharT, _Traits, _Allocator>::front() const _NOEXCEPT
3262{
3263    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3264    return *data();
3265}
3266
3267template <class _CharT, class _Traits, class _Allocator>
3268inline
3269typename basic_string<_CharT, _Traits, _Allocator>::reference
3270basic_string<_CharT, _Traits, _Allocator>::back() _NOEXCEPT
3271{
3272    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3273    return *(__get_pointer() + size() - 1);
3274}
3275
3276template <class _CharT, class _Traits, class _Allocator>
3277inline
3278typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3279basic_string<_CharT, _Traits, _Allocator>::back() const _NOEXCEPT
3280{
3281    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3282    return *(data() + size() - 1);
3283}
3284
3285template <class _CharT, class _Traits, class _Allocator>
3286typename basic_string<_CharT, _Traits, _Allocator>::size_type
3287basic_string<_CharT, _Traits, _Allocator>::copy(value_type* __s, size_type __n, size_type __pos) const
3288{
3289    size_type __sz = size();
3290    if (__pos > __sz)
3291        this->__throw_out_of_range();
3292    size_type __rlen = _VSTD::min(__n, __sz - __pos);
3293    traits_type::copy(__s, data() + __pos, __rlen);
3294    return __rlen;
3295}
3296
3297template <class _CharT, class _Traits, class _Allocator>
3298inline
3299basic_string<_CharT, _Traits, _Allocator>
3300basic_string<_CharT, _Traits, _Allocator>::substr(size_type __pos, size_type __n) const
3301{
3302    return basic_string(*this, __pos, __n, __alloc());
3303}
3304
3305template <class _CharT, class _Traits, class _Allocator>
3306inline
3307void
3308basic_string<_CharT, _Traits, _Allocator>::swap(basic_string& __str)
3309#if _LIBCPP_STD_VER >= 14
3310        _NOEXCEPT
3311#else
3312        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
3313                    __is_nothrow_swappable<allocator_type>::value)
3314#endif
3315{
3316#if _LIBCPP_DEBUG_LEVEL >= 2
3317    if (!__is_long())
3318        __get_db()->__invalidate_all(this);
3319    if (!__str.__is_long())
3320        __get_db()->__invalidate_all(&__str);
3321    __get_db()->swap(this, &__str);
3322#endif
3323    _LIBCPP_ASSERT(
3324        __alloc_traits::propagate_on_container_swap::value ||
3325        __alloc_traits::is_always_equal::value ||
3326        __alloc() == __str.__alloc(), "swapping non-equal allocators");
3327    _VSTD::swap(__r_.first(), __str.__r_.first());
3328    __swap_allocator(__alloc(), __str.__alloc());
3329}
3330
3331// find
3332
3333template <class _Traits>
3334struct _LIBCPP_HIDDEN __traits_eq
3335{
3336    typedef typename _Traits::char_type char_type;
3337    _LIBCPP_INLINE_VISIBILITY
3338    bool operator()(const char_type& __x, const char_type& __y) _NOEXCEPT
3339        {return _Traits::eq(__x, __y);}
3340};
3341
3342template<class _CharT, class _Traits, class _Allocator>
3343typename basic_string<_CharT, _Traits, _Allocator>::size_type
3344basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3345                                                size_type __pos,
3346                                                size_type __n) const _NOEXCEPT
3347{
3348    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find(): received nullptr");
3349    return __str_find<value_type, size_type, traits_type, npos>
3350        (data(), size(), __s, __pos, __n);
3351}
3352
3353template<class _CharT, class _Traits, class _Allocator>
3354inline
3355typename basic_string<_CharT, _Traits, _Allocator>::size_type
3356basic_string<_CharT, _Traits, _Allocator>::find(const basic_string& __str,
3357                                                size_type __pos) const _NOEXCEPT
3358{
3359    return __str_find<value_type, size_type, traits_type, npos>
3360        (data(), size(), __str.data(), __pos, __str.size());
3361}
3362
3363template<class _CharT, class _Traits, class _Allocator>
3364template <class _Tp>
3365_EnableIf
3366<
3367    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3368    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3369>
3370basic_string<_CharT, _Traits, _Allocator>::find(const _Tp &__t,
3371                                                size_type __pos) const
3372{
3373    __self_view __sv = __t;
3374    return __str_find<value_type, size_type, traits_type, npos>
3375        (data(), size(), __sv.data(), __pos, __sv.size());
3376}
3377
3378template<class _CharT, class _Traits, class _Allocator>
3379inline
3380typename basic_string<_CharT, _Traits, _Allocator>::size_type
3381basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3382                                                size_type __pos) const _NOEXCEPT
3383{
3384    _LIBCPP_ASSERT(__s != nullptr, "string::find(): received nullptr");
3385    return __str_find<value_type, size_type, traits_type, npos>
3386        (data(), size(), __s, __pos, traits_type::length(__s));
3387}
3388
3389template<class _CharT, class _Traits, class _Allocator>
3390typename basic_string<_CharT, _Traits, _Allocator>::size_type
3391basic_string<_CharT, _Traits, _Allocator>::find(value_type __c,
3392                                                size_type __pos) const _NOEXCEPT
3393{
3394    return __str_find<value_type, size_type, traits_type, npos>
3395        (data(), size(), __c, __pos);
3396}
3397
3398// rfind
3399
3400template<class _CharT, class _Traits, class _Allocator>
3401typename basic_string<_CharT, _Traits, _Allocator>::size_type
3402basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3403                                                 size_type __pos,
3404                                                 size_type __n) const _NOEXCEPT
3405{
3406    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::rfind(): received nullptr");
3407    return __str_rfind<value_type, size_type, traits_type, npos>
3408        (data(), size(), __s, __pos, __n);
3409}
3410
3411template<class _CharT, class _Traits, class _Allocator>
3412inline
3413typename basic_string<_CharT, _Traits, _Allocator>::size_type
3414basic_string<_CharT, _Traits, _Allocator>::rfind(const basic_string& __str,
3415                                                 size_type __pos) const _NOEXCEPT
3416{
3417    return __str_rfind<value_type, size_type, traits_type, npos>
3418        (data(), size(), __str.data(), __pos, __str.size());
3419}
3420
3421template<class _CharT, class _Traits, class _Allocator>
3422template <class _Tp>
3423_EnableIf
3424<
3425    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3426    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3427>
3428basic_string<_CharT, _Traits, _Allocator>::rfind(const _Tp& __t,
3429                                                size_type __pos) const
3430{
3431    __self_view __sv = __t;
3432    return __str_rfind<value_type, size_type, traits_type, npos>
3433        (data(), size(), __sv.data(), __pos, __sv.size());
3434}
3435
3436template<class _CharT, class _Traits, class _Allocator>
3437inline
3438typename basic_string<_CharT, _Traits, _Allocator>::size_type
3439basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3440                                                 size_type __pos) const _NOEXCEPT
3441{
3442    _LIBCPP_ASSERT(__s != nullptr, "string::rfind(): received nullptr");
3443    return __str_rfind<value_type, size_type, traits_type, npos>
3444        (data(), size(), __s, __pos, traits_type::length(__s));
3445}
3446
3447template<class _CharT, class _Traits, class _Allocator>
3448typename basic_string<_CharT, _Traits, _Allocator>::size_type
3449basic_string<_CharT, _Traits, _Allocator>::rfind(value_type __c,
3450                                                 size_type __pos) const _NOEXCEPT
3451{
3452    return __str_rfind<value_type, size_type, traits_type, npos>
3453        (data(), size(), __c, __pos);
3454}
3455
3456// find_first_of
3457
3458template<class _CharT, class _Traits, class _Allocator>
3459typename basic_string<_CharT, _Traits, _Allocator>::size_type
3460basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3461                                                         size_type __pos,
3462                                                         size_type __n) const _NOEXCEPT
3463{
3464    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_of(): received nullptr");
3465    return __str_find_first_of<value_type, size_type, traits_type, npos>
3466        (data(), size(), __s, __pos, __n);
3467}
3468
3469template<class _CharT, class _Traits, class _Allocator>
3470inline
3471typename basic_string<_CharT, _Traits, _Allocator>::size_type
3472basic_string<_CharT, _Traits, _Allocator>::find_first_of(const basic_string& __str,
3473                                                         size_type __pos) const _NOEXCEPT
3474{
3475    return __str_find_first_of<value_type, size_type, traits_type, npos>
3476        (data(), size(), __str.data(), __pos, __str.size());
3477}
3478
3479template<class _CharT, class _Traits, class _Allocator>
3480template <class _Tp>
3481_EnableIf
3482<
3483    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3484    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3485>
3486basic_string<_CharT, _Traits, _Allocator>::find_first_of(const _Tp& __t,
3487                                                size_type __pos) const
3488{
3489    __self_view __sv = __t;
3490    return __str_find_first_of<value_type, size_type, traits_type, npos>
3491        (data(), size(), __sv.data(), __pos, __sv.size());
3492}
3493
3494template<class _CharT, class _Traits, class _Allocator>
3495inline
3496typename basic_string<_CharT, _Traits, _Allocator>::size_type
3497basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3498                                                         size_type __pos) const _NOEXCEPT
3499{
3500    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_of(): received nullptr");
3501    return __str_find_first_of<value_type, size_type, traits_type, npos>
3502        (data(), size(), __s, __pos, traits_type::length(__s));
3503}
3504
3505template<class _CharT, class _Traits, class _Allocator>
3506inline
3507typename basic_string<_CharT, _Traits, _Allocator>::size_type
3508basic_string<_CharT, _Traits, _Allocator>::find_first_of(value_type __c,
3509                                                         size_type __pos) const _NOEXCEPT
3510{
3511    return find(__c, __pos);
3512}
3513
3514// find_last_of
3515
3516template<class _CharT, class _Traits, class _Allocator>
3517typename basic_string<_CharT, _Traits, _Allocator>::size_type
3518basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3519                                                        size_type __pos,
3520                                                        size_type __n) const _NOEXCEPT
3521{
3522    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_of(): received nullptr");
3523    return __str_find_last_of<value_type, size_type, traits_type, npos>
3524        (data(), size(), __s, __pos, __n);
3525}
3526
3527template<class _CharT, class _Traits, class _Allocator>
3528inline
3529typename basic_string<_CharT, _Traits, _Allocator>::size_type
3530basic_string<_CharT, _Traits, _Allocator>::find_last_of(const basic_string& __str,
3531                                                        size_type __pos) const _NOEXCEPT
3532{
3533    return __str_find_last_of<value_type, size_type, traits_type, npos>
3534        (data(), size(), __str.data(), __pos, __str.size());
3535}
3536
3537template<class _CharT, class _Traits, class _Allocator>
3538template <class _Tp>
3539_EnableIf
3540<
3541    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3542    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3543>
3544basic_string<_CharT, _Traits, _Allocator>::find_last_of(const _Tp& __t,
3545                                                size_type __pos) const
3546{
3547    __self_view __sv = __t;
3548    return __str_find_last_of<value_type, size_type, traits_type, npos>
3549        (data(), size(), __sv.data(), __pos, __sv.size());
3550}
3551
3552template<class _CharT, class _Traits, class _Allocator>
3553inline
3554typename basic_string<_CharT, _Traits, _Allocator>::size_type
3555basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3556                                                        size_type __pos) const _NOEXCEPT
3557{
3558    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_of(): received nullptr");
3559    return __str_find_last_of<value_type, size_type, traits_type, npos>
3560        (data(), size(), __s, __pos, traits_type::length(__s));
3561}
3562
3563template<class _CharT, class _Traits, class _Allocator>
3564inline
3565typename basic_string<_CharT, _Traits, _Allocator>::size_type
3566basic_string<_CharT, _Traits, _Allocator>::find_last_of(value_type __c,
3567                                                        size_type __pos) const _NOEXCEPT
3568{
3569    return rfind(__c, __pos);
3570}
3571
3572// find_first_not_of
3573
3574template<class _CharT, class _Traits, class _Allocator>
3575typename basic_string<_CharT, _Traits, _Allocator>::size_type
3576basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3577                                                             size_type __pos,
3578                                                             size_type __n) const _NOEXCEPT
3579{
3580    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_not_of(): received nullptr");
3581    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3582        (data(), size(), __s, __pos, __n);
3583}
3584
3585template<class _CharT, class _Traits, class _Allocator>
3586inline
3587typename basic_string<_CharT, _Traits, _Allocator>::size_type
3588basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const basic_string& __str,
3589                                                             size_type __pos) const _NOEXCEPT
3590{
3591    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3592        (data(), size(), __str.data(), __pos, __str.size());
3593}
3594
3595template<class _CharT, class _Traits, class _Allocator>
3596template <class _Tp>
3597_EnableIf
3598<
3599    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3600    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3601>
3602basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const _Tp& __t,
3603                                                size_type __pos) const
3604{
3605    __self_view __sv = __t;
3606    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3607        (data(), size(), __sv.data(), __pos, __sv.size());
3608}
3609
3610template<class _CharT, class _Traits, class _Allocator>
3611inline
3612typename basic_string<_CharT, _Traits, _Allocator>::size_type
3613basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3614                                                             size_type __pos) const _NOEXCEPT
3615{
3616    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_not_of(): received nullptr");
3617    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3618        (data(), size(), __s, __pos, traits_type::length(__s));
3619}
3620
3621template<class _CharT, class _Traits, class _Allocator>
3622inline
3623typename basic_string<_CharT, _Traits, _Allocator>::size_type
3624basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(value_type __c,
3625                                                             size_type __pos) const _NOEXCEPT
3626{
3627    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3628        (data(), size(), __c, __pos);
3629}
3630
3631// find_last_not_of
3632
3633template<class _CharT, class _Traits, class _Allocator>
3634typename basic_string<_CharT, _Traits, _Allocator>::size_type
3635basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3636                                                            size_type __pos,
3637                                                            size_type __n) const _NOEXCEPT
3638{
3639    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_not_of(): received nullptr");
3640    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3641        (data(), size(), __s, __pos, __n);
3642}
3643
3644template<class _CharT, class _Traits, class _Allocator>
3645inline
3646typename basic_string<_CharT, _Traits, _Allocator>::size_type
3647basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const basic_string& __str,
3648                                                            size_type __pos) const _NOEXCEPT
3649{
3650    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3651        (data(), size(), __str.data(), __pos, __str.size());
3652}
3653
3654template<class _CharT, class _Traits, class _Allocator>
3655template <class _Tp>
3656_EnableIf
3657<
3658    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3659    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3660>
3661basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const _Tp& __t,
3662                                                size_type __pos) const
3663{
3664    __self_view __sv = __t;
3665    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3666        (data(), size(), __sv.data(), __pos, __sv.size());
3667}
3668
3669template<class _CharT, class _Traits, class _Allocator>
3670inline
3671typename basic_string<_CharT, _Traits, _Allocator>::size_type
3672basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3673                                                            size_type __pos) const _NOEXCEPT
3674{
3675    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_not_of(): received nullptr");
3676    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3677        (data(), size(), __s, __pos, traits_type::length(__s));
3678}
3679
3680template<class _CharT, class _Traits, class _Allocator>
3681inline
3682typename basic_string<_CharT, _Traits, _Allocator>::size_type
3683basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(value_type __c,
3684                                                            size_type __pos) const _NOEXCEPT
3685{
3686    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3687        (data(), size(), __c, __pos);
3688}
3689
3690// compare
3691
3692template <class _CharT, class _Traits, class _Allocator>
3693template <class _Tp>
3694_EnableIf
3695<
3696    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3697    int
3698>
3699basic_string<_CharT, _Traits, _Allocator>::compare(const _Tp& __t) const
3700{
3701    __self_view __sv = __t;
3702    size_t __lhs_sz = size();
3703    size_t __rhs_sz = __sv.size();
3704    int __result = traits_type::compare(data(), __sv.data(),
3705                                        _VSTD::min(__lhs_sz, __rhs_sz));
3706    if (__result != 0)
3707        return __result;
3708    if (__lhs_sz < __rhs_sz)
3709        return -1;
3710    if (__lhs_sz > __rhs_sz)
3711        return 1;
3712    return 0;
3713}
3714
3715template <class _CharT, class _Traits, class _Allocator>
3716inline
3717int
3718basic_string<_CharT, _Traits, _Allocator>::compare(const basic_string& __str) const _NOEXCEPT
3719{
3720    return compare(__self_view(__str));
3721}
3722
3723template <class _CharT, class _Traits, class _Allocator>
3724int
3725basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3726                                                   size_type __n1,
3727                                                   const value_type* __s,
3728                                                   size_type __n2) const
3729{
3730    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::compare(): received nullptr");
3731    size_type __sz = size();
3732    if (__pos1 > __sz || __n2 == npos)
3733        this->__throw_out_of_range();
3734    size_type __rlen = _VSTD::min(__n1, __sz - __pos1);
3735    int __r = traits_type::compare(data() + __pos1, __s, _VSTD::min(__rlen, __n2));
3736    if (__r == 0)
3737    {
3738        if (__rlen < __n2)
3739            __r = -1;
3740        else if (__rlen > __n2)
3741            __r = 1;
3742    }
3743    return __r;
3744}
3745
3746template <class _CharT, class _Traits, class _Allocator>
3747template <class _Tp>
3748_EnableIf
3749<
3750    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3751    int
3752>
3753basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3754                                                   size_type __n1,
3755                                                   const _Tp& __t) const
3756{
3757    __self_view __sv = __t;
3758    return compare(__pos1, __n1, __sv.data(), __sv.size());
3759}
3760
3761template <class _CharT, class _Traits, class _Allocator>
3762inline
3763int
3764basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3765                                                   size_type __n1,
3766                                                   const basic_string& __str) const
3767{
3768    return compare(__pos1, __n1, __str.data(), __str.size());
3769}
3770
3771template <class _CharT, class _Traits, class _Allocator>
3772template <class _Tp>
3773_EnableIf
3774<
3775    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
3776    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
3777    int
3778>
3779basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3780                                                   size_type __n1,
3781                                                   const _Tp& __t,
3782                                                   size_type __pos2,
3783                                                   size_type __n2) const
3784{
3785    __self_view __sv = __t;
3786    return __self_view(*this).substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
3787}
3788
3789template <class _CharT, class _Traits, class _Allocator>
3790int
3791basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3792                                                   size_type __n1,
3793                                                   const basic_string& __str,
3794                                                   size_type __pos2,
3795                                                   size_type __n2) const
3796{
3797        return compare(__pos1, __n1, __self_view(__str), __pos2, __n2);
3798}
3799
3800template <class _CharT, class _Traits, class _Allocator>
3801int
3802basic_string<_CharT, _Traits, _Allocator>::compare(const value_type* __s) const _NOEXCEPT
3803{
3804    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3805    return compare(0, npos, __s, traits_type::length(__s));
3806}
3807
3808template <class _CharT, class _Traits, class _Allocator>
3809int
3810basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3811                                                   size_type __n1,
3812                                                   const value_type* __s) const
3813{
3814    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3815    return compare(__pos1, __n1, __s, traits_type::length(__s));
3816}
3817
3818// __invariants
3819
3820template<class _CharT, class _Traits, class _Allocator>
3821inline
3822bool
3823basic_string<_CharT, _Traits, _Allocator>::__invariants() const
3824{
3825    if (size() > capacity())
3826        return false;
3827    if (capacity() < __min_cap - 1)
3828        return false;
3829    if (data() == 0)
3830        return false;
3831    if (data()[size()] != value_type(0))
3832        return false;
3833    return true;
3834}
3835
3836// __clear_and_shrink
3837
3838template<class _CharT, class _Traits, class _Allocator>
3839inline
3840void
3841basic_string<_CharT, _Traits, _Allocator>::__clear_and_shrink() _NOEXCEPT
3842{
3843    clear();
3844    if(__is_long())
3845    {
3846        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), capacity() + 1);
3847        __set_long_cap(0);
3848        __set_short_size(0);
3849    }
3850}
3851
3852// operator==
3853
3854template<class _CharT, class _Traits, class _Allocator>
3855inline _LIBCPP_INLINE_VISIBILITY
3856bool
3857operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
3858           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3859{
3860    size_t __lhs_sz = __lhs.size();
3861    return __lhs_sz == __rhs.size() && _Traits::compare(__lhs.data(),
3862                                                        __rhs.data(),
3863                                                        __lhs_sz) == 0;
3864}
3865
3866template<class _Allocator>
3867inline _LIBCPP_INLINE_VISIBILITY
3868bool
3869operator==(const basic_string<char, char_traits<char>, _Allocator>& __lhs,
3870           const basic_string<char, char_traits<char>, _Allocator>& __rhs) _NOEXCEPT
3871{
3872    size_t __lhs_sz = __lhs.size();
3873    if (__lhs_sz != __rhs.size())
3874        return false;
3875    const char* __lp = __lhs.data();
3876    const char* __rp = __rhs.data();
3877    if (__lhs.__is_long())
3878        return char_traits<char>::compare(__lp, __rp, __lhs_sz) == 0;
3879    for (; __lhs_sz != 0; --__lhs_sz, ++__lp, ++__rp)
3880        if (*__lp != *__rp)
3881            return false;
3882    return true;
3883}
3884
3885template<class _CharT, class _Traits, class _Allocator>
3886inline _LIBCPP_INLINE_VISIBILITY
3887bool
3888operator==(const _CharT* __lhs,
3889           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3890{
3891    typedef basic_string<_CharT, _Traits, _Allocator> _String;
3892    _LIBCPP_ASSERT(__lhs != nullptr, "operator==(char*, basic_string): received nullptr");
3893    size_t __lhs_len = _Traits::length(__lhs);
3894    if (__lhs_len != __rhs.size()) return false;
3895    return __rhs.compare(0, _String::npos, __lhs, __lhs_len) == 0;
3896}
3897
3898template<class _CharT, class _Traits, class _Allocator>
3899inline _LIBCPP_INLINE_VISIBILITY
3900bool
3901operator==(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
3902           const _CharT* __rhs) _NOEXCEPT
3903{
3904    typedef basic_string<_CharT, _Traits, _Allocator> _String;
3905    _LIBCPP_ASSERT(__rhs != nullptr, "operator==(basic_string, char*): received nullptr");
3906    size_t __rhs_len = _Traits::length(__rhs);
3907    if (__rhs_len != __lhs.size()) return false;
3908    return __lhs.compare(0, _String::npos, __rhs, __rhs_len) == 0;
3909}
3910
3911template<class _CharT, class _Traits, class _Allocator>
3912inline _LIBCPP_INLINE_VISIBILITY
3913bool
3914operator!=(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
3915           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3916{
3917    return !(__lhs == __rhs);
3918}
3919
3920template<class _CharT, class _Traits, class _Allocator>
3921inline _LIBCPP_INLINE_VISIBILITY
3922bool
3923operator!=(const _CharT* __lhs,
3924           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3925{
3926    return !(__lhs == __rhs);
3927}
3928
3929template<class _CharT, class _Traits, class _Allocator>
3930inline _LIBCPP_INLINE_VISIBILITY
3931bool
3932operator!=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
3933           const _CharT* __rhs) _NOEXCEPT
3934{
3935    return !(__lhs == __rhs);
3936}
3937
3938// operator<
3939
3940template<class _CharT, class _Traits, class _Allocator>
3941inline _LIBCPP_INLINE_VISIBILITY
3942bool
3943operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
3944           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3945{
3946    return __lhs.compare(__rhs) < 0;
3947}
3948
3949template<class _CharT, class _Traits, class _Allocator>
3950inline _LIBCPP_INLINE_VISIBILITY
3951bool
3952operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
3953           const _CharT* __rhs) _NOEXCEPT
3954{
3955    return __lhs.compare(__rhs) < 0;
3956}
3957
3958template<class _CharT, class _Traits, class _Allocator>
3959inline _LIBCPP_INLINE_VISIBILITY
3960bool
3961operator< (const _CharT* __lhs,
3962           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3963{
3964    return __rhs.compare(__lhs) > 0;
3965}
3966
3967// operator>
3968
3969template<class _CharT, class _Traits, class _Allocator>
3970inline _LIBCPP_INLINE_VISIBILITY
3971bool
3972operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
3973           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3974{
3975    return __rhs < __lhs;
3976}
3977
3978template<class _CharT, class _Traits, class _Allocator>
3979inline _LIBCPP_INLINE_VISIBILITY
3980bool
3981operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
3982           const _CharT* __rhs) _NOEXCEPT
3983{
3984    return __rhs < __lhs;
3985}
3986
3987template<class _CharT, class _Traits, class _Allocator>
3988inline _LIBCPP_INLINE_VISIBILITY
3989bool
3990operator> (const _CharT* __lhs,
3991           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3992{
3993    return __rhs < __lhs;
3994}
3995
3996// operator<=
3997
3998template<class _CharT, class _Traits, class _Allocator>
3999inline _LIBCPP_INLINE_VISIBILITY
4000bool
4001operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4002           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4003{
4004    return !(__rhs < __lhs);
4005}
4006
4007template<class _CharT, class _Traits, class _Allocator>
4008inline _LIBCPP_INLINE_VISIBILITY
4009bool
4010operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4011           const _CharT* __rhs) _NOEXCEPT
4012{
4013    return !(__rhs < __lhs);
4014}
4015
4016template<class _CharT, class _Traits, class _Allocator>
4017inline _LIBCPP_INLINE_VISIBILITY
4018bool
4019operator<=(const _CharT* __lhs,
4020           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4021{
4022    return !(__rhs < __lhs);
4023}
4024
4025// operator>=
4026
4027template<class _CharT, class _Traits, class _Allocator>
4028inline _LIBCPP_INLINE_VISIBILITY
4029bool
4030operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4031           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4032{
4033    return !(__lhs < __rhs);
4034}
4035
4036template<class _CharT, class _Traits, class _Allocator>
4037inline _LIBCPP_INLINE_VISIBILITY
4038bool
4039operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4040           const _CharT* __rhs) _NOEXCEPT
4041{
4042    return !(__lhs < __rhs);
4043}
4044
4045template<class _CharT, class _Traits, class _Allocator>
4046inline _LIBCPP_INLINE_VISIBILITY
4047bool
4048operator>=(const _CharT* __lhs,
4049           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4050{
4051    return !(__lhs < __rhs);
4052}
4053
4054// operator +
4055
4056template<class _CharT, class _Traits, class _Allocator>
4057basic_string<_CharT, _Traits, _Allocator>
4058operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4059          const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4060{
4061    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4062    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4063    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4064    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4065    __r.append(__rhs.data(), __rhs_sz);
4066    return __r;
4067}
4068
4069template<class _CharT, class _Traits, class _Allocator>
4070basic_string<_CharT, _Traits, _Allocator>
4071operator+(const _CharT* __lhs , const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4072{
4073    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4074    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = _Traits::length(__lhs);
4075    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4076    __r.__init(__lhs, __lhs_sz, __lhs_sz + __rhs_sz);
4077    __r.append(__rhs.data(), __rhs_sz);
4078    return __r;
4079}
4080
4081template<class _CharT, class _Traits, class _Allocator>
4082basic_string<_CharT, _Traits, _Allocator>
4083operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4084{
4085    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4086    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4087    __r.__init(&__lhs, 1, 1 + __rhs_sz);
4088    __r.append(__rhs.data(), __rhs_sz);
4089    return __r;
4090}
4091
4092template<class _CharT, class _Traits, class _Allocator>
4093inline
4094basic_string<_CharT, _Traits, _Allocator>
4095operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs)
4096{
4097    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4098    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4099    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = _Traits::length(__rhs);
4100    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4101    __r.append(__rhs, __rhs_sz);
4102    return __r;
4103}
4104
4105template<class _CharT, class _Traits, class _Allocator>
4106basic_string<_CharT, _Traits, _Allocator>
4107operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, _CharT __rhs)
4108{
4109    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4110    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4111    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + 1);
4112    __r.push_back(__rhs);
4113    return __r;
4114}
4115
4116#ifndef _LIBCPP_CXX03_LANG
4117
4118template<class _CharT, class _Traits, class _Allocator>
4119inline _LIBCPP_INLINE_VISIBILITY
4120basic_string<_CharT, _Traits, _Allocator>
4121operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4122{
4123    return _VSTD::move(__lhs.append(__rhs));
4124}
4125
4126template<class _CharT, class _Traits, class _Allocator>
4127inline _LIBCPP_INLINE_VISIBILITY
4128basic_string<_CharT, _Traits, _Allocator>
4129operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4130{
4131    return _VSTD::move(__rhs.insert(0, __lhs));
4132}
4133
4134template<class _CharT, class _Traits, class _Allocator>
4135inline _LIBCPP_INLINE_VISIBILITY
4136basic_string<_CharT, _Traits, _Allocator>
4137operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4138{
4139    return _VSTD::move(__lhs.append(__rhs));
4140}
4141
4142template<class _CharT, class _Traits, class _Allocator>
4143inline _LIBCPP_INLINE_VISIBILITY
4144basic_string<_CharT, _Traits, _Allocator>
4145operator+(const _CharT* __lhs , basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4146{
4147    return _VSTD::move(__rhs.insert(0, __lhs));
4148}
4149
4150template<class _CharT, class _Traits, class _Allocator>
4151inline _LIBCPP_INLINE_VISIBILITY
4152basic_string<_CharT, _Traits, _Allocator>
4153operator+(_CharT __lhs, basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4154{
4155    __rhs.insert(__rhs.begin(), __lhs);
4156    return _VSTD::move(__rhs);
4157}
4158
4159template<class _CharT, class _Traits, class _Allocator>
4160inline _LIBCPP_INLINE_VISIBILITY
4161basic_string<_CharT, _Traits, _Allocator>
4162operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const _CharT* __rhs)
4163{
4164    return _VSTD::move(__lhs.append(__rhs));
4165}
4166
4167template<class _CharT, class _Traits, class _Allocator>
4168inline _LIBCPP_INLINE_VISIBILITY
4169basic_string<_CharT, _Traits, _Allocator>
4170operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, _CharT __rhs)
4171{
4172    __lhs.push_back(__rhs);
4173    return _VSTD::move(__lhs);
4174}
4175
4176#endif  // _LIBCPP_CXX03_LANG
4177
4178// swap
4179
4180template<class _CharT, class _Traits, class _Allocator>
4181inline _LIBCPP_INLINE_VISIBILITY
4182void
4183swap(basic_string<_CharT, _Traits, _Allocator>& __lhs,
4184     basic_string<_CharT, _Traits, _Allocator>& __rhs)
4185     _NOEXCEPT_(_NOEXCEPT_(__lhs.swap(__rhs)))
4186{
4187    __lhs.swap(__rhs);
4188}
4189
4190#ifndef _LIBCPP_NO_HAS_CHAR8_T
4191typedef basic_string<char8_t> u8string;
4192#endif
4193
4194#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
4195typedef basic_string<char16_t> u16string;
4196typedef basic_string<char32_t> u32string;
4197#endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
4198
4199_LIBCPP_FUNC_VIS int                stoi  (const string& __str, size_t* __idx = 0, int __base = 10);
4200_LIBCPP_FUNC_VIS long               stol  (const string& __str, size_t* __idx = 0, int __base = 10);
4201_LIBCPP_FUNC_VIS unsigned long      stoul (const string& __str, size_t* __idx = 0, int __base = 10);
4202_LIBCPP_FUNC_VIS long long          stoll (const string& __str, size_t* __idx = 0, int __base = 10);
4203_LIBCPP_FUNC_VIS unsigned long long stoull(const string& __str, size_t* __idx = 0, int __base = 10);
4204
4205_LIBCPP_FUNC_VIS float       stof (const string& __str, size_t* __idx = 0);
4206_LIBCPP_FUNC_VIS double      stod (const string& __str, size_t* __idx = 0);
4207_LIBCPP_FUNC_VIS long double stold(const string& __str, size_t* __idx = 0);
4208
4209_LIBCPP_FUNC_VIS string to_string(int __val);
4210_LIBCPP_FUNC_VIS string to_string(unsigned __val);
4211_LIBCPP_FUNC_VIS string to_string(long __val);
4212_LIBCPP_FUNC_VIS string to_string(unsigned long __val);
4213_LIBCPP_FUNC_VIS string to_string(long long __val);
4214_LIBCPP_FUNC_VIS string to_string(unsigned long long __val);
4215_LIBCPP_FUNC_VIS string to_string(float __val);
4216_LIBCPP_FUNC_VIS string to_string(double __val);
4217_LIBCPP_FUNC_VIS string to_string(long double __val);
4218
4219_LIBCPP_FUNC_VIS int                stoi  (const wstring& __str, size_t* __idx = 0, int __base = 10);
4220_LIBCPP_FUNC_VIS long               stol  (const wstring& __str, size_t* __idx = 0, int __base = 10);
4221_LIBCPP_FUNC_VIS unsigned long      stoul (const wstring& __str, size_t* __idx = 0, int __base = 10);
4222_LIBCPP_FUNC_VIS long long          stoll (const wstring& __str, size_t* __idx = 0, int __base = 10);
4223_LIBCPP_FUNC_VIS unsigned long long stoull(const wstring& __str, size_t* __idx = 0, int __base = 10);
4224
4225_LIBCPP_FUNC_VIS float       stof (const wstring& __str, size_t* __idx = 0);
4226_LIBCPP_FUNC_VIS double      stod (const wstring& __str, size_t* __idx = 0);
4227_LIBCPP_FUNC_VIS long double stold(const wstring& __str, size_t* __idx = 0);
4228
4229_LIBCPP_FUNC_VIS wstring to_wstring(int __val);
4230_LIBCPP_FUNC_VIS wstring to_wstring(unsigned __val);
4231_LIBCPP_FUNC_VIS wstring to_wstring(long __val);
4232_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long __val);
4233_LIBCPP_FUNC_VIS wstring to_wstring(long long __val);
4234_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long long __val);
4235_LIBCPP_FUNC_VIS wstring to_wstring(float __val);
4236_LIBCPP_FUNC_VIS wstring to_wstring(double __val);
4237_LIBCPP_FUNC_VIS wstring to_wstring(long double __val);
4238
4239template<class _CharT, class _Traits, class _Allocator>
4240_LIBCPP_FUNC_VIS
4241const typename basic_string<_CharT, _Traits, _Allocator>::size_type
4242               basic_string<_CharT, _Traits, _Allocator>::npos;
4243
4244template <class _CharT, class _Allocator>
4245struct _LIBCPP_TEMPLATE_VIS
4246    hash<basic_string<_CharT, char_traits<_CharT>, _Allocator> >
4247    : public unary_function<
4248          basic_string<_CharT, char_traits<_CharT>, _Allocator>, size_t>
4249{
4250    size_t
4251    operator()(const basic_string<_CharT, char_traits<_CharT>, _Allocator>& __val) const _NOEXCEPT
4252    { return __do_string_hash(__val.data(), __val.data() + __val.size()); }
4253};
4254
4255
4256template<class _CharT, class _Traits, class _Allocator>
4257basic_ostream<_CharT, _Traits>&
4258operator<<(basic_ostream<_CharT, _Traits>& __os,
4259           const basic_string<_CharT, _Traits, _Allocator>& __str);
4260
4261template<class _CharT, class _Traits, class _Allocator>
4262basic_istream<_CharT, _Traits>&
4263operator>>(basic_istream<_CharT, _Traits>& __is,
4264           basic_string<_CharT, _Traits, _Allocator>& __str);
4265
4266template<class _CharT, class _Traits, class _Allocator>
4267basic_istream<_CharT, _Traits>&
4268getline(basic_istream<_CharT, _Traits>& __is,
4269        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4270
4271template<class _CharT, class _Traits, class _Allocator>
4272inline _LIBCPP_INLINE_VISIBILITY
4273basic_istream<_CharT, _Traits>&
4274getline(basic_istream<_CharT, _Traits>& __is,
4275        basic_string<_CharT, _Traits, _Allocator>& __str);
4276
4277#ifndef _LIBCPP_CXX03_LANG
4278
4279template<class _CharT, class _Traits, class _Allocator>
4280inline _LIBCPP_INLINE_VISIBILITY
4281basic_istream<_CharT, _Traits>&
4282getline(basic_istream<_CharT, _Traits>&& __is,
4283        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4284
4285template<class _CharT, class _Traits, class _Allocator>
4286inline _LIBCPP_INLINE_VISIBILITY
4287basic_istream<_CharT, _Traits>&
4288getline(basic_istream<_CharT, _Traits>&& __is,
4289        basic_string<_CharT, _Traits, _Allocator>& __str);
4290
4291#endif  // _LIBCPP_CXX03_LANG
4292
4293#if _LIBCPP_STD_VER > 17
4294template<class _CharT, class _Traits, class _Allocator, class _Up>
4295inline _LIBCPP_INLINE_VISIBILITY
4296void erase(basic_string<_CharT, _Traits, _Allocator>& __str, const _Up& __v)
4297{ __str.erase(_VSTD::remove(__str.begin(), __str.end(), __v), __str.end()); }
4298
4299template<class _CharT, class _Traits, class _Allocator, class _Predicate>
4300inline _LIBCPP_INLINE_VISIBILITY
4301void erase_if(basic_string<_CharT, _Traits, _Allocator>& __str, _Predicate __pred)
4302{ __str.erase(_VSTD::remove_if(__str.begin(), __str.end(), __pred), __str.end()); }
4303#endif
4304
4305#if _LIBCPP_DEBUG_LEVEL >= 2
4306
4307template<class _CharT, class _Traits, class _Allocator>
4308bool
4309basic_string<_CharT, _Traits, _Allocator>::__dereferenceable(const const_iterator* __i) const
4310{
4311    return this->data() <= _VSTD::__to_address(__i->base()) &&
4312           _VSTD::__to_address(__i->base()) < this->data() + this->size();
4313}
4314
4315template<class _CharT, class _Traits, class _Allocator>
4316bool
4317basic_string<_CharT, _Traits, _Allocator>::__decrementable(const const_iterator* __i) const
4318{
4319    return this->data() < _VSTD::__to_address(__i->base()) &&
4320           _VSTD::__to_address(__i->base()) <= this->data() + this->size();
4321}
4322
4323template<class _CharT, class _Traits, class _Allocator>
4324bool
4325basic_string<_CharT, _Traits, _Allocator>::__addable(const const_iterator* __i, ptrdiff_t __n) const
4326{
4327    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4328    return this->data() <= __p && __p <= this->data() + this->size();
4329}
4330
4331template<class _CharT, class _Traits, class _Allocator>
4332bool
4333basic_string<_CharT, _Traits, _Allocator>::__subscriptable(const const_iterator* __i, ptrdiff_t __n) const
4334{
4335    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4336    return this->data() <= __p && __p < this->data() + this->size();
4337}
4338
4339#endif  // _LIBCPP_DEBUG_LEVEL >= 2
4340
4341_LIBCPP_STRING_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
4342_LIBCPP_STRING_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
4343
4344#if _LIBCPP_STD_VER > 11
4345// Literal suffixes for basic_string [basic.string.literals]
4346inline namespace literals
4347{
4348  inline namespace string_literals
4349  {
4350    inline _LIBCPP_INLINE_VISIBILITY
4351    basic_string<char> operator "" s( const char *__str, size_t __len )
4352    {
4353        return basic_string<char> (__str, __len);
4354    }
4355
4356    inline _LIBCPP_INLINE_VISIBILITY
4357    basic_string<wchar_t> operator "" s( const wchar_t *__str, size_t __len )
4358    {
4359        return basic_string<wchar_t> (__str, __len);
4360    }
4361
4362#ifndef _LIBCPP_NO_HAS_CHAR8_T
4363    inline _LIBCPP_INLINE_VISIBILITY
4364    basic_string<char8_t> operator "" s(const char8_t *__str, size_t __len) _NOEXCEPT
4365    {
4366        return basic_string<char8_t> (__str, __len);
4367    }
4368#endif
4369
4370    inline _LIBCPP_INLINE_VISIBILITY
4371    basic_string<char16_t> operator "" s( const char16_t *__str, size_t __len )
4372    {
4373        return basic_string<char16_t> (__str, __len);
4374    }
4375
4376    inline _LIBCPP_INLINE_VISIBILITY
4377    basic_string<char32_t> operator "" s( const char32_t *__str, size_t __len )
4378    {
4379        return basic_string<char32_t> (__str, __len);
4380    }
4381  }
4382}
4383#endif
4384
4385_LIBCPP_END_NAMESPACE_STD
4386
4387_LIBCPP_POP_MACROS
4388
4389#endif  // _LIBCPP_STRING
4390