xref: /llvm-project-15.0.7/libcxx/include/string (revision b4fb705e)
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    // Slow path for the (inlined) copy constructor for 'long' strings.
1553    // Always externally instantiated and not inlined.
1554    // Requires that __s is zero terminated.
1555    // The main reason for this function to exist is because for unstable, we
1556    // want to allow inlining of the copy constructor. However, we don't want
1557    // to call the __init() functions as those are marked as inline which may
1558    // result in over-aggressive inlining by the compiler, where our aim is
1559    // to only inline the fast path code directly in the ctor.
1560    void __init_copy_ctor_external(const value_type* __s, size_type __sz);
1561
1562    template <class _InputIterator>
1563    inline
1564    _EnableIf
1565    <
1566        __is_exactly_cpp17_input_iterator<_InputIterator>::value
1567    >
1568    __init(_InputIterator __first, _InputIterator __last);
1569
1570    template <class _ForwardIterator>
1571    inline
1572    _EnableIf
1573    <
1574        __is_cpp17_forward_iterator<_ForwardIterator>::value
1575    >
1576    __init(_ForwardIterator __first, _ForwardIterator __last);
1577
1578    void __grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1579                   size_type __n_copy,  size_type __n_del,     size_type __n_add = 0);
1580    void __grow_by_and_replace(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1581                               size_type __n_copy,  size_type __n_del,
1582                               size_type __n_add, const value_type* __p_new_stuff);
1583
1584    // __assign_no_alias is invoked for assignment operations where we
1585    // have proof that the input does not alias the current instance.
1586    // For example, operator=(basic_string) performs a 'self' check.
1587    template <bool __is_short>
1588    basic_string& __assign_no_alias(const value_type* __s, size_type __n);
1589
1590    _LIBCPP_INLINE_VISIBILITY
1591    void __erase_to_end(size_type __pos);
1592
1593    // __erase_external_with_move is invoked for erase() invocations where
1594    // `n ~= npos`, likely requiring memory moves on the string data.
1595    void __erase_external_with_move(size_type __pos, size_type __n);
1596
1597    _LIBCPP_INLINE_VISIBILITY
1598    void __copy_assign_alloc(const basic_string& __str)
1599        {__copy_assign_alloc(__str, integral_constant<bool,
1600                      __alloc_traits::propagate_on_container_copy_assignment::value>());}
1601
1602    _LIBCPP_INLINE_VISIBILITY
1603    void __copy_assign_alloc(const basic_string& __str, true_type)
1604        {
1605            if (__alloc() == __str.__alloc())
1606                __alloc() = __str.__alloc();
1607            else
1608            {
1609                if (!__str.__is_long())
1610                {
1611                    __clear_and_shrink();
1612                    __alloc() = __str.__alloc();
1613                }
1614                else
1615                {
1616                    allocator_type __a = __str.__alloc();
1617                    pointer __p = __alloc_traits::allocate(__a, __str.__get_long_cap());
1618                    __clear_and_shrink();
1619                    __alloc() = _VSTD::move(__a);
1620                    __set_long_pointer(__p);
1621                    __set_long_cap(__str.__get_long_cap());
1622                    __set_long_size(__str.size());
1623                }
1624            }
1625        }
1626
1627    _LIBCPP_INLINE_VISIBILITY
1628    void __copy_assign_alloc(const basic_string&, false_type) _NOEXCEPT
1629        {}
1630
1631#ifndef _LIBCPP_CXX03_LANG
1632    _LIBCPP_INLINE_VISIBILITY
1633    void __move_assign(basic_string& __str, false_type)
1634        _NOEXCEPT_(__alloc_traits::is_always_equal::value);
1635    _LIBCPP_INLINE_VISIBILITY
1636    void __move_assign(basic_string& __str, true_type)
1637#if _LIBCPP_STD_VER > 14
1638        _NOEXCEPT;
1639#else
1640        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
1641#endif
1642#endif
1643
1644    _LIBCPP_INLINE_VISIBILITY
1645    void
1646    __move_assign_alloc(basic_string& __str)
1647        _NOEXCEPT_(
1648            !__alloc_traits::propagate_on_container_move_assignment::value ||
1649            is_nothrow_move_assignable<allocator_type>::value)
1650    {__move_assign_alloc(__str, integral_constant<bool,
1651                      __alloc_traits::propagate_on_container_move_assignment::value>());}
1652
1653    _LIBCPP_INLINE_VISIBILITY
1654    void __move_assign_alloc(basic_string& __c, true_type)
1655        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
1656        {
1657            __alloc() = _VSTD::move(__c.__alloc());
1658        }
1659
1660    _LIBCPP_INLINE_VISIBILITY
1661    void __move_assign_alloc(basic_string&, false_type)
1662        _NOEXCEPT
1663        {}
1664
1665    _LIBCPP_INLINE_VISIBILITY void __invalidate_all_iterators();
1666    _LIBCPP_INLINE_VISIBILITY void __invalidate_iterators_past(size_type);
1667
1668    friend basic_string operator+<>(const basic_string&, const basic_string&);
1669    friend basic_string operator+<>(const value_type*, const basic_string&);
1670    friend basic_string operator+<>(value_type, const basic_string&);
1671    friend basic_string operator+<>(const basic_string&, const value_type*);
1672    friend basic_string operator+<>(const basic_string&, value_type);
1673};
1674
1675// These declarations must appear before any functions are implicitly used
1676// so that they have the correct visibility specifier.
1677#ifdef _LIBCPP_ABI_STRING_OPTIMIZED_EXTERNAL_INSTANTIATION
1678_LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
1679_LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
1680#else
1681_LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
1682_LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
1683#endif
1684
1685
1686#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
1687template<class _InputIterator,
1688         class _CharT = typename iterator_traits<_InputIterator>::value_type,
1689         class _Allocator = allocator<_CharT>,
1690         class = _EnableIf<__is_cpp17_input_iterator<_InputIterator>::value>,
1691         class = _EnableIf<__is_allocator<_Allocator>::value>
1692         >
1693basic_string(_InputIterator, _InputIterator, _Allocator = _Allocator())
1694  -> basic_string<_CharT, char_traits<_CharT>, _Allocator>;
1695
1696template<class _CharT,
1697         class _Traits,
1698         class _Allocator = allocator<_CharT>,
1699         class = _EnableIf<__is_allocator<_Allocator>::value>
1700         >
1701explicit basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
1702  -> basic_string<_CharT, _Traits, _Allocator>;
1703
1704template<class _CharT,
1705         class _Traits,
1706         class _Allocator = allocator<_CharT>,
1707         class = _EnableIf<__is_allocator<_Allocator>::value>,
1708         class _Sz = typename allocator_traits<_Allocator>::size_type
1709         >
1710basic_string(basic_string_view<_CharT, _Traits>, _Sz, _Sz, const _Allocator& = _Allocator())
1711  -> basic_string<_CharT, _Traits, _Allocator>;
1712#endif
1713
1714template <class _CharT, class _Traits, class _Allocator>
1715inline
1716void
1717basic_string<_CharT, _Traits, _Allocator>::__invalidate_all_iterators()
1718{
1719#if _LIBCPP_DEBUG_LEVEL >= 2
1720    __get_db()->__invalidate_all(this);
1721#endif  // _LIBCPP_DEBUG_LEVEL >= 2
1722}
1723
1724template <class _CharT, class _Traits, class _Allocator>
1725inline
1726void
1727basic_string<_CharT, _Traits, _Allocator>::__invalidate_iterators_past(size_type
1728#if _LIBCPP_DEBUG_LEVEL >= 2
1729                                                                        __pos
1730#endif
1731                                                                      )
1732{
1733#if _LIBCPP_DEBUG_LEVEL >= 2
1734    __c_node* __c = __get_db()->__find_c_and_lock(this);
1735    if (__c)
1736    {
1737        const_pointer __new_last = __get_pointer() + __pos;
1738        for (__i_node** __p = __c->end_; __p != __c->beg_; )
1739        {
1740            --__p;
1741            const_iterator* __i = static_cast<const_iterator*>((*__p)->__i_);
1742            if (__i->base() > __new_last)
1743            {
1744                (*__p)->__c_ = nullptr;
1745                if (--__c->end_ != __p)
1746                    memmove(__p, __p+1, (__c->end_ - __p)*sizeof(__i_node*));
1747            }
1748        }
1749        __get_db()->unlock();
1750    }
1751#endif  // _LIBCPP_DEBUG_LEVEL >= 2
1752}
1753
1754template <class _CharT, class _Traits, class _Allocator>
1755inline
1756basic_string<_CharT, _Traits, _Allocator>::basic_string()
1757    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
1758     : __r_(__default_init_tag(), __default_init_tag())
1759{
1760#if _LIBCPP_DEBUG_LEVEL >= 2
1761    __get_db()->__insert_c(this);
1762#endif
1763    __zero();
1764}
1765
1766template <class _CharT, class _Traits, class _Allocator>
1767inline
1768basic_string<_CharT, _Traits, _Allocator>::basic_string(const allocator_type& __a)
1769#if _LIBCPP_STD_VER <= 14
1770        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value)
1771#else
1772        _NOEXCEPT
1773#endif
1774: __r_(__default_init_tag(), __a)
1775{
1776#if _LIBCPP_DEBUG_LEVEL >= 2
1777    __get_db()->__insert_c(this);
1778#endif
1779    __zero();
1780}
1781
1782template <class _CharT, class _Traits, class _Allocator>
1783void basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s,
1784                                                       size_type __sz,
1785                                                       size_type __reserve)
1786{
1787    if (__reserve > max_size())
1788        this->__throw_length_error();
1789    pointer __p;
1790    if (__reserve < __min_cap)
1791    {
1792        __set_short_size(__sz);
1793        __p = __get_short_pointer();
1794    }
1795    else
1796    {
1797        size_type __cap = __recommend(__reserve);
1798        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1799        __set_long_pointer(__p);
1800        __set_long_cap(__cap+1);
1801        __set_long_size(__sz);
1802    }
1803    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1804    traits_type::assign(__p[__sz], value_type());
1805}
1806
1807template <class _CharT, class _Traits, class _Allocator>
1808void
1809basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s, size_type __sz)
1810{
1811    if (__sz > max_size())
1812        this->__throw_length_error();
1813    pointer __p;
1814    if (__sz < __min_cap)
1815    {
1816        __set_short_size(__sz);
1817        __p = __get_short_pointer();
1818    }
1819    else
1820    {
1821        size_type __cap = __recommend(__sz);
1822        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1823        __set_long_pointer(__p);
1824        __set_long_cap(__cap+1);
1825        __set_long_size(__sz);
1826    }
1827    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1828    traits_type::assign(__p[__sz], value_type());
1829}
1830
1831template <class _CharT, class _Traits, class _Allocator>
1832template <class>
1833basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, const _Allocator& __a)
1834    : __r_(__default_init_tag(), __a)
1835{
1836    _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*, allocator) detected nullptr");
1837    __init(__s, traits_type::length(__s));
1838#if _LIBCPP_DEBUG_LEVEL >= 2
1839    __get_db()->__insert_c(this);
1840#endif
1841}
1842
1843template <class _CharT, class _Traits, class _Allocator>
1844inline
1845basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n)
1846     : __r_(__default_init_tag(), __default_init_tag())
1847{
1848    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n) detected nullptr");
1849    __init(__s, __n);
1850#if _LIBCPP_DEBUG_LEVEL >= 2
1851    __get_db()->__insert_c(this);
1852#endif
1853}
1854
1855template <class _CharT, class _Traits, class _Allocator>
1856inline
1857basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n, const _Allocator& __a)
1858    : __r_(__default_init_tag(), __a)
1859{
1860    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n, allocator) detected nullptr");
1861    __init(__s, __n);
1862#if _LIBCPP_DEBUG_LEVEL >= 2
1863    __get_db()->__insert_c(this);
1864#endif
1865}
1866
1867template <class _CharT, class _Traits, class _Allocator>
1868basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str)
1869    : __r_(__default_init_tag(), __alloc_traits::select_on_container_copy_construction(__str.__alloc()))
1870{
1871    if (!__str.__is_long())
1872        __r_.first().__r = __str.__r_.first().__r;
1873    else
1874        __init_copy_ctor_external(_VSTD::__to_address(__str.__get_long_pointer()),
1875                                  __str.__get_long_size());
1876
1877#if _LIBCPP_DEBUG_LEVEL >= 2
1878    __get_db()->__insert_c(this);
1879#endif
1880}
1881
1882template <class _CharT, class _Traits, class _Allocator>
1883basic_string<_CharT, _Traits, _Allocator>::basic_string(
1884    const basic_string& __str, const allocator_type& __a)
1885    : __r_(__default_init_tag(), __a)
1886{
1887    if (!__str.__is_long())
1888        __r_.first().__r = __str.__r_.first().__r;
1889    else
1890        __init_copy_ctor_external(_VSTD::__to_address(__str.__get_long_pointer()),
1891                                  __str.__get_long_size());
1892#if _LIBCPP_DEBUG_LEVEL >= 2
1893    __get_db()->__insert_c(this);
1894#endif
1895}
1896
1897template <class _CharT, class _Traits, class _Allocator>
1898void basic_string<_CharT, _Traits, _Allocator>::__init_copy_ctor_external(
1899    const value_type* __s, size_type __sz) {
1900  pointer __p;
1901  if (__sz < __min_cap) {
1902    __p = __get_short_pointer();
1903    __set_short_size(__sz);
1904  } else {
1905    if (__sz > max_size())
1906      this->__throw_length_error();
1907    size_t __cap = __recommend(__sz);
1908    __p = __alloc_traits::allocate(__alloc(), __cap + 1);
1909    __set_long_pointer(__p);
1910    __set_long_cap(__cap + 1);
1911    __set_long_size(__sz);
1912  }
1913  traits_type::copy(_VSTD::__to_address(__p), __s, __sz + 1);
1914}
1915
1916#ifndef _LIBCPP_CXX03_LANG
1917
1918template <class _CharT, class _Traits, class _Allocator>
1919inline
1920basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str)
1921#if _LIBCPP_STD_VER <= 14
1922        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
1923#else
1924        _NOEXCEPT
1925#endif
1926    : __r_(_VSTD::move(__str.__r_))
1927{
1928    __str.__zero();
1929#if _LIBCPP_DEBUG_LEVEL >= 2
1930    __get_db()->__insert_c(this);
1931    if (__is_long())
1932        __get_db()->swap(this, &__str);
1933#endif
1934}
1935
1936template <class _CharT, class _Traits, class _Allocator>
1937inline
1938basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str, const allocator_type& __a)
1939    : __r_(__default_init_tag(), __a)
1940{
1941    if (__str.__is_long() && __a != __str.__alloc()) // copy, not move
1942        __init(_VSTD::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
1943    else
1944    {
1945        __r_.first().__r = __str.__r_.first().__r;
1946        __str.__zero();
1947    }
1948#if _LIBCPP_DEBUG_LEVEL >= 2
1949    __get_db()->__insert_c(this);
1950    if (__is_long())
1951        __get_db()->swap(this, &__str);
1952#endif
1953}
1954
1955#endif  // _LIBCPP_CXX03_LANG
1956
1957template <class _CharT, class _Traits, class _Allocator>
1958void
1959basic_string<_CharT, _Traits, _Allocator>::__init(size_type __n, value_type __c)
1960{
1961    if (__n > max_size())
1962        this->__throw_length_error();
1963    pointer __p;
1964    if (__n < __min_cap)
1965    {
1966        __set_short_size(__n);
1967        __p = __get_short_pointer();
1968    }
1969    else
1970    {
1971        size_type __cap = __recommend(__n);
1972        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1973        __set_long_pointer(__p);
1974        __set_long_cap(__cap+1);
1975        __set_long_size(__n);
1976    }
1977    traits_type::assign(_VSTD::__to_address(__p), __n, __c);
1978    traits_type::assign(__p[__n], value_type());
1979}
1980
1981template <class _CharT, class _Traits, class _Allocator>
1982inline
1983basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c)
1984     : __r_(__default_init_tag(), __default_init_tag())
1985{
1986    __init(__n, __c);
1987#if _LIBCPP_DEBUG_LEVEL >= 2
1988    __get_db()->__insert_c(this);
1989#endif
1990}
1991
1992template <class _CharT, class _Traits, class _Allocator>
1993template <class>
1994basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c, const _Allocator& __a)
1995    : __r_(__default_init_tag(), __a)
1996{
1997    __init(__n, __c);
1998#if _LIBCPP_DEBUG_LEVEL >= 2
1999    __get_db()->__insert_c(this);
2000#endif
2001}
2002
2003template <class _CharT, class _Traits, class _Allocator>
2004basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str,
2005                                                        size_type __pos, size_type __n,
2006                                                        const _Allocator& __a)
2007    : __r_(__default_init_tag(), __a)
2008{
2009    size_type __str_sz = __str.size();
2010    if (__pos > __str_sz)
2011        this->__throw_out_of_range();
2012    __init(__str.data() + __pos, _VSTD::min(__n, __str_sz - __pos));
2013#if _LIBCPP_DEBUG_LEVEL >= 2
2014    __get_db()->__insert_c(this);
2015#endif
2016}
2017
2018template <class _CharT, class _Traits, class _Allocator>
2019inline
2020basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str, size_type __pos,
2021                                                        const _Allocator& __a)
2022    : __r_(__default_init_tag(), __a)
2023{
2024    size_type __str_sz = __str.size();
2025    if (__pos > __str_sz)
2026        this->__throw_out_of_range();
2027    __init(__str.data() + __pos, __str_sz - __pos);
2028#if _LIBCPP_DEBUG_LEVEL >= 2
2029    __get_db()->__insert_c(this);
2030#endif
2031}
2032
2033template <class _CharT, class _Traits, class _Allocator>
2034template <class _Tp, class>
2035basic_string<_CharT, _Traits, _Allocator>::basic_string(
2036             const _Tp& __t, size_type __pos, size_type __n, const allocator_type& __a)
2037    : __r_(__default_init_tag(), __a)
2038{
2039    __self_view __sv0 = __t;
2040    __self_view __sv = __sv0.substr(__pos, __n);
2041    __init(__sv.data(), __sv.size());
2042#if _LIBCPP_DEBUG_LEVEL >= 2
2043    __get_db()->__insert_c(this);
2044#endif
2045}
2046
2047template <class _CharT, class _Traits, class _Allocator>
2048template <class _Tp, class>
2049basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t)
2050     : __r_(__default_init_tag(), __default_init_tag())
2051{
2052    __self_view __sv = __t;
2053    __init(__sv.data(), __sv.size());
2054#if _LIBCPP_DEBUG_LEVEL >= 2
2055    __get_db()->__insert_c(this);
2056#endif
2057}
2058
2059template <class _CharT, class _Traits, class _Allocator>
2060template <class _Tp, class>
2061basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t, const _Allocator& __a)
2062    : __r_(__default_init_tag(), __a)
2063{
2064    __self_view __sv = __t;
2065    __init(__sv.data(), __sv.size());
2066#if _LIBCPP_DEBUG_LEVEL >= 2
2067    __get_db()->__insert_c(this);
2068#endif
2069}
2070
2071template <class _CharT, class _Traits, class _Allocator>
2072template <class _InputIterator>
2073_EnableIf
2074<
2075    __is_exactly_cpp17_input_iterator<_InputIterator>::value
2076>
2077basic_string<_CharT, _Traits, _Allocator>::__init(_InputIterator __first, _InputIterator __last)
2078{
2079    __zero();
2080#ifndef _LIBCPP_NO_EXCEPTIONS
2081    try
2082    {
2083#endif  // _LIBCPP_NO_EXCEPTIONS
2084    for (; __first != __last; ++__first)
2085        push_back(*__first);
2086#ifndef _LIBCPP_NO_EXCEPTIONS
2087    }
2088    catch (...)
2089    {
2090        if (__is_long())
2091            __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2092        throw;
2093    }
2094#endif  // _LIBCPP_NO_EXCEPTIONS
2095}
2096
2097template <class _CharT, class _Traits, class _Allocator>
2098template <class _ForwardIterator>
2099_EnableIf
2100<
2101    __is_cpp17_forward_iterator<_ForwardIterator>::value
2102>
2103basic_string<_CharT, _Traits, _Allocator>::__init(_ForwardIterator __first, _ForwardIterator __last)
2104{
2105    size_type __sz = static_cast<size_type>(_VSTD::distance(__first, __last));
2106    if (__sz > max_size())
2107        this->__throw_length_error();
2108    pointer __p;
2109    if (__sz < __min_cap)
2110    {
2111        __set_short_size(__sz);
2112        __p = __get_short_pointer();
2113    }
2114    else
2115    {
2116        size_type __cap = __recommend(__sz);
2117        __p = __alloc_traits::allocate(__alloc(), __cap+1);
2118        __set_long_pointer(__p);
2119        __set_long_cap(__cap+1);
2120        __set_long_size(__sz);
2121    }
2122    for (; __first != __last; ++__first, (void) ++__p)
2123        traits_type::assign(*__p, *__first);
2124    traits_type::assign(*__p, value_type());
2125}
2126
2127template <class _CharT, class _Traits, class _Allocator>
2128template<class _InputIterator, class>
2129inline
2130basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last)
2131     : __r_(__default_init_tag(), __default_init_tag())
2132{
2133    __init(__first, __last);
2134#if _LIBCPP_DEBUG_LEVEL >= 2
2135    __get_db()->__insert_c(this);
2136#endif
2137}
2138
2139template <class _CharT, class _Traits, class _Allocator>
2140template<class _InputIterator, class>
2141inline
2142basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last,
2143                                                        const allocator_type& __a)
2144    : __r_(__default_init_tag(), __a)
2145{
2146    __init(__first, __last);
2147#if _LIBCPP_DEBUG_LEVEL >= 2
2148    __get_db()->__insert_c(this);
2149#endif
2150}
2151
2152#ifndef _LIBCPP_CXX03_LANG
2153
2154template <class _CharT, class _Traits, class _Allocator>
2155inline
2156basic_string<_CharT, _Traits, _Allocator>::basic_string(
2157    initializer_list<_CharT> __il)
2158     : __r_(__default_init_tag(), __default_init_tag())
2159{
2160    __init(__il.begin(), __il.end());
2161#if _LIBCPP_DEBUG_LEVEL >= 2
2162    __get_db()->__insert_c(this);
2163#endif
2164}
2165
2166template <class _CharT, class _Traits, class _Allocator>
2167inline
2168
2169basic_string<_CharT, _Traits, _Allocator>::basic_string(
2170    initializer_list<_CharT> __il, const _Allocator& __a)
2171    : __r_(__default_init_tag(), __a)
2172{
2173    __init(__il.begin(), __il.end());
2174#if _LIBCPP_DEBUG_LEVEL >= 2
2175    __get_db()->__insert_c(this);
2176#endif
2177}
2178
2179#endif  // _LIBCPP_CXX03_LANG
2180
2181template <class _CharT, class _Traits, class _Allocator>
2182basic_string<_CharT, _Traits, _Allocator>::~basic_string()
2183{
2184#if _LIBCPP_DEBUG_LEVEL >= 2
2185    __get_db()->__erase_c(this);
2186#endif
2187    if (__is_long())
2188        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2189}
2190
2191template <class _CharT, class _Traits, class _Allocator>
2192void
2193basic_string<_CharT, _Traits, _Allocator>::__grow_by_and_replace
2194    (size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2195     size_type __n_copy,  size_type __n_del,     size_type __n_add, const value_type* __p_new_stuff)
2196{
2197    size_type __ms = max_size();
2198    if (__delta_cap > __ms - __old_cap - 1)
2199        this->__throw_length_error();
2200    pointer __old_p = __get_pointer();
2201    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2202                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2203                          __ms - 1;
2204    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2205    __invalidate_all_iterators();
2206    if (__n_copy != 0)
2207        traits_type::copy(_VSTD::__to_address(__p),
2208                          _VSTD::__to_address(__old_p), __n_copy);
2209    if (__n_add != 0)
2210        traits_type::copy(_VSTD::__to_address(__p) + __n_copy, __p_new_stuff, __n_add);
2211    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2212    if (__sec_cp_sz != 0)
2213        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2214                          _VSTD::__to_address(__old_p) + __n_copy + __n_del, __sec_cp_sz);
2215    if (__old_cap+1 != __min_cap)
2216        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2217    __set_long_pointer(__p);
2218    __set_long_cap(__cap+1);
2219    __old_sz = __n_copy + __n_add + __sec_cp_sz;
2220    __set_long_size(__old_sz);
2221    traits_type::assign(__p[__old_sz], value_type());
2222}
2223
2224template <class _CharT, class _Traits, class _Allocator>
2225void
2226basic_string<_CharT, _Traits, _Allocator>::__grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2227                                                     size_type __n_copy,  size_type __n_del,     size_type __n_add)
2228{
2229    size_type __ms = max_size();
2230    if (__delta_cap > __ms - __old_cap)
2231        this->__throw_length_error();
2232    pointer __old_p = __get_pointer();
2233    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2234                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2235                          __ms - 1;
2236    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2237    __invalidate_all_iterators();
2238    if (__n_copy != 0)
2239        traits_type::copy(_VSTD::__to_address(__p),
2240                          _VSTD::__to_address(__old_p), __n_copy);
2241    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2242    if (__sec_cp_sz != 0)
2243        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2244                          _VSTD::__to_address(__old_p) + __n_copy + __n_del,
2245                          __sec_cp_sz);
2246    if (__old_cap+1 != __min_cap)
2247        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2248    __set_long_pointer(__p);
2249    __set_long_cap(__cap+1);
2250}
2251
2252// assign
2253
2254template <class _CharT, class _Traits, class _Allocator>
2255template <bool __is_short>
2256basic_string<_CharT, _Traits, _Allocator>&
2257basic_string<_CharT, _Traits, _Allocator>::__assign_no_alias(
2258    const value_type* __s, size_type __n) {
2259  size_type __cap = __is_short ? __min_cap : __get_long_cap();
2260  if (__n < __cap) {
2261    pointer __p = __is_short ? __get_short_pointer() : __get_long_pointer();
2262    __is_short ? __set_short_size(__n) : __set_long_size(__n);
2263    traits_type::copy(_VSTD::__to_address(__p), __s, __n);
2264    traits_type::assign(__p[__n], value_type());
2265    __invalidate_iterators_past(__n);
2266  } else {
2267    size_type __sz = __is_short ? __get_short_size() : __get_long_size();
2268    __grow_by_and_replace(__cap - 1, __n - __cap + 1, __sz, 0, __sz, __n, __s);
2269  }
2270  return *this;
2271}
2272
2273template <class _CharT, class _Traits, class _Allocator>
2274basic_string<_CharT, _Traits, _Allocator>&
2275basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s, size_type __n)
2276{
2277    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::assign received nullptr");
2278    size_type __cap = capacity();
2279    if (__cap >= __n)
2280    {
2281        value_type* __p = _VSTD::__to_address(__get_pointer());
2282        traits_type::move(__p, __s, __n);
2283        traits_type::assign(__p[__n], value_type());
2284        __set_size(__n);
2285        __invalidate_iterators_past(__n);
2286    }
2287    else
2288    {
2289        size_type __sz = size();
2290        __grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s);
2291    }
2292    return *this;
2293}
2294
2295template <class _CharT, class _Traits, class _Allocator>
2296basic_string<_CharT, _Traits, _Allocator>&
2297basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
2298{
2299    size_type __cap = capacity();
2300    if (__cap < __n)
2301    {
2302        size_type __sz = size();
2303        __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2304    }
2305    else
2306        __invalidate_iterators_past(__n);
2307    value_type* __p = _VSTD::__to_address(__get_pointer());
2308    traits_type::assign(__p, __n, __c);
2309    traits_type::assign(__p[__n], value_type());
2310    __set_size(__n);
2311    return *this;
2312}
2313
2314template <class _CharT, class _Traits, class _Allocator>
2315basic_string<_CharT, _Traits, _Allocator>&
2316basic_string<_CharT, _Traits, _Allocator>::operator=(value_type __c)
2317{
2318    pointer __p;
2319    if (__is_long())
2320    {
2321        __p = __get_long_pointer();
2322        __set_long_size(1);
2323    }
2324    else
2325    {
2326        __p = __get_short_pointer();
2327        __set_short_size(1);
2328    }
2329    traits_type::assign(*__p, __c);
2330    traits_type::assign(*++__p, value_type());
2331    __invalidate_iterators_past(1);
2332    return *this;
2333}
2334
2335template <class _CharT, class _Traits, class _Allocator>
2336basic_string<_CharT, _Traits, _Allocator>&
2337basic_string<_CharT, _Traits, _Allocator>::operator=(const basic_string& __str)
2338{
2339  if (this != &__str) {
2340    __copy_assign_alloc(__str);
2341    if (!__is_long()) {
2342      if (!__str.__is_long()) {
2343        __r_.first().__r = __str.__r_.first().__r;
2344      } else {
2345        return __assign_no_alias<true>(__str.data(), __str.size());
2346      }
2347    } else {
2348      return __assign_no_alias<false>(__str.data(), __str.size());
2349    }
2350  }
2351  return *this;
2352}
2353
2354#ifndef _LIBCPP_CXX03_LANG
2355
2356template <class _CharT, class _Traits, class _Allocator>
2357inline
2358void
2359basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, false_type)
2360    _NOEXCEPT_(__alloc_traits::is_always_equal::value)
2361{
2362    if (__alloc() != __str.__alloc())
2363        assign(__str);
2364    else
2365        __move_assign(__str, true_type());
2366}
2367
2368template <class _CharT, class _Traits, class _Allocator>
2369inline
2370void
2371basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, true_type)
2372#if _LIBCPP_STD_VER > 14
2373    _NOEXCEPT
2374#else
2375    _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
2376#endif
2377{
2378  if (__is_long()) {
2379    __alloc_traits::deallocate(__alloc(), __get_long_pointer(),
2380                               __get_long_cap());
2381#if _LIBCPP_STD_VER <= 14
2382    if (!is_nothrow_move_assignable<allocator_type>::value) {
2383      __set_short_size(0);
2384      traits_type::assign(__get_short_pointer()[0], value_type());
2385    }
2386#endif
2387  }
2388  __move_assign_alloc(__str);
2389  __r_.first() = __str.__r_.first();
2390  __str.__set_short_size(0);
2391  traits_type::assign(__str.__get_short_pointer()[0], value_type());
2392}
2393
2394template <class _CharT, class _Traits, class _Allocator>
2395inline
2396basic_string<_CharT, _Traits, _Allocator>&
2397basic_string<_CharT, _Traits, _Allocator>::operator=(basic_string&& __str)
2398    _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
2399{
2400    __move_assign(__str, integral_constant<bool,
2401          __alloc_traits::propagate_on_container_move_assignment::value>());
2402    return *this;
2403}
2404
2405#endif
2406
2407template <class _CharT, class _Traits, class _Allocator>
2408template<class _InputIterator>
2409_EnableIf
2410<
2411     __is_exactly_cpp17_input_iterator <_InputIterator>::value
2412          || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
2413    basic_string<_CharT, _Traits, _Allocator>&
2414>
2415basic_string<_CharT, _Traits, _Allocator>::assign(_InputIterator __first, _InputIterator __last)
2416{
2417    const basic_string __temp(__first, __last, __alloc());
2418    assign(__temp.data(), __temp.size());
2419    return *this;
2420}
2421
2422template <class _CharT, class _Traits, class _Allocator>
2423template<class _ForwardIterator>
2424_EnableIf
2425<
2426    __is_cpp17_forward_iterator<_ForwardIterator>::value
2427         && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
2428    basic_string<_CharT, _Traits, _Allocator>&
2429>
2430basic_string<_CharT, _Traits, _Allocator>::assign(_ForwardIterator __first, _ForwardIterator __last)
2431{
2432    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2433    size_type __cap = capacity();
2434    if (__cap < __n)
2435    {
2436        size_type __sz = size();
2437        __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2438    }
2439    else
2440        __invalidate_iterators_past(__n);
2441    pointer __p = __get_pointer();
2442    for (; __first != __last; ++__first, ++__p)
2443        traits_type::assign(*__p, *__first);
2444    traits_type::assign(*__p, value_type());
2445    __set_size(__n);
2446    return *this;
2447}
2448
2449template <class _CharT, class _Traits, class _Allocator>
2450basic_string<_CharT, _Traits, _Allocator>&
2451basic_string<_CharT, _Traits, _Allocator>::assign(const basic_string& __str, size_type __pos, size_type __n)
2452{
2453    size_type __sz = __str.size();
2454    if (__pos > __sz)
2455        this->__throw_out_of_range();
2456    return assign(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2457}
2458
2459template <class _CharT, class _Traits, class _Allocator>
2460template <class _Tp>
2461_EnableIf
2462<
2463    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
2464    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2465    basic_string<_CharT, _Traits, _Allocator>&
2466>
2467basic_string<_CharT, _Traits, _Allocator>::assign(const _Tp & __t, size_type __pos, size_type __n)
2468{
2469    __self_view __sv = __t;
2470    size_type __sz = __sv.size();
2471    if (__pos > __sz)
2472        this->__throw_out_of_range();
2473    return assign(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2474}
2475
2476
2477template <class _CharT, class _Traits, class _Allocator>
2478basic_string<_CharT, _Traits, _Allocator>&
2479basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s)
2480{
2481    _LIBCPP_ASSERT(__s != nullptr, "string::assign received nullptr");
2482    return assign(__s, traits_type::length(__s));
2483}
2484
2485// append
2486
2487template <class _CharT, class _Traits, class _Allocator>
2488basic_string<_CharT, _Traits, _Allocator>&
2489basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s, size_type __n)
2490{
2491    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::append received nullptr");
2492    size_type __cap = capacity();
2493    size_type __sz = size();
2494    if (__cap - __sz >= __n)
2495    {
2496        if (__n)
2497        {
2498            value_type* __p = _VSTD::__to_address(__get_pointer());
2499            traits_type::copy(__p + __sz, __s, __n);
2500            __sz += __n;
2501            __set_size(__sz);
2502            traits_type::assign(__p[__sz], value_type());
2503        }
2504    }
2505    else
2506        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __sz, 0, __n, __s);
2507    return *this;
2508}
2509
2510template <class _CharT, class _Traits, class _Allocator>
2511basic_string<_CharT, _Traits, _Allocator>&
2512basic_string<_CharT, _Traits, _Allocator>::append(size_type __n, value_type __c)
2513{
2514    if (__n)
2515    {
2516        size_type __cap = capacity();
2517        size_type __sz = size();
2518        if (__cap - __sz < __n)
2519            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2520        pointer __p = __get_pointer();
2521        traits_type::assign(_VSTD::__to_address(__p) + __sz, __n, __c);
2522        __sz += __n;
2523        __set_size(__sz);
2524        traits_type::assign(__p[__sz], value_type());
2525    }
2526    return *this;
2527}
2528
2529template <class _CharT, class _Traits, class _Allocator>
2530inline void
2531basic_string<_CharT, _Traits, _Allocator>::__append_default_init(size_type __n)
2532{
2533    if (__n)
2534    {
2535        size_type __cap = capacity();
2536        size_type __sz = size();
2537        if (__cap - __sz < __n)
2538            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2539        pointer __p = __get_pointer();
2540        __sz += __n;
2541        __set_size(__sz);
2542        traits_type::assign(__p[__sz], value_type());
2543    }
2544}
2545
2546template <class _CharT, class _Traits, class _Allocator>
2547void
2548basic_string<_CharT, _Traits, _Allocator>::push_back(value_type __c)
2549{
2550    bool __is_short = !__is_long();
2551    size_type __cap;
2552    size_type __sz;
2553    if (__is_short)
2554    {
2555        __cap = __min_cap - 1;
2556        __sz = __get_short_size();
2557    }
2558    else
2559    {
2560        __cap = __get_long_cap() - 1;
2561        __sz = __get_long_size();
2562    }
2563    if (__sz == __cap)
2564    {
2565        __grow_by(__cap, 1, __sz, __sz, 0);
2566        __is_short = !__is_long();
2567    }
2568    pointer __p;
2569    if (__is_short)
2570    {
2571        __p = __get_short_pointer() + __sz;
2572        __set_short_size(__sz+1);
2573    }
2574    else
2575    {
2576        __p = __get_long_pointer() + __sz;
2577        __set_long_size(__sz+1);
2578    }
2579    traits_type::assign(*__p, __c);
2580    traits_type::assign(*++__p, value_type());
2581}
2582
2583template <class _Tp>
2584bool __ptr_in_range (const _Tp* __p, const _Tp* __first, const _Tp* __last)
2585{
2586    return __first <= __p && __p < __last;
2587}
2588
2589template <class _Tp1, class _Tp2>
2590bool __ptr_in_range (const _Tp1*, const _Tp2*, const _Tp2*)
2591{
2592    return false;
2593}
2594
2595template <class _CharT, class _Traits, class _Allocator>
2596template<class _ForwardIterator>
2597basic_string<_CharT, _Traits, _Allocator>&
2598basic_string<_CharT, _Traits, _Allocator>::__append_forward_unsafe(
2599    _ForwardIterator __first, _ForwardIterator __last)
2600{
2601    static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value,
2602                  "function requires a ForwardIterator");
2603    size_type __sz = size();
2604    size_type __cap = capacity();
2605    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2606    if (__n)
2607    {
2608        typedef typename iterator_traits<_ForwardIterator>::reference _CharRef;
2609        _CharRef __tmp_ref = *__first;
2610        if (__ptr_in_range(_VSTD::addressof(__tmp_ref), data(), data() + size()))
2611        {
2612            const basic_string __temp (__first, __last, __alloc());
2613            append(__temp.data(), __temp.size());
2614        }
2615        else
2616        {
2617            if (__cap - __sz < __n)
2618                __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2619            pointer __p = __get_pointer() + __sz;
2620            for (; __first != __last; ++__p, ++__first)
2621                traits_type::assign(*__p, *__first);
2622            traits_type::assign(*__p, value_type());
2623            __set_size(__sz + __n);
2624        }
2625    }
2626    return *this;
2627}
2628
2629template <class _CharT, class _Traits, class _Allocator>
2630inline
2631basic_string<_CharT, _Traits, _Allocator>&
2632basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str)
2633{
2634    return append(__str.data(), __str.size());
2635}
2636
2637template <class _CharT, class _Traits, class _Allocator>
2638basic_string<_CharT, _Traits, _Allocator>&
2639basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str, size_type __pos, size_type __n)
2640{
2641    size_type __sz = __str.size();
2642    if (__pos > __sz)
2643        this->__throw_out_of_range();
2644    return append(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2645}
2646
2647template <class _CharT, class _Traits, class _Allocator>
2648template <class _Tp>
2649    _EnableIf
2650    <
2651        __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2652        basic_string<_CharT, _Traits, _Allocator>&
2653    >
2654basic_string<_CharT, _Traits, _Allocator>::append(const _Tp & __t, size_type __pos, size_type __n)
2655{
2656    __self_view __sv = __t;
2657    size_type __sz = __sv.size();
2658    if (__pos > __sz)
2659        this->__throw_out_of_range();
2660    return append(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2661}
2662
2663template <class _CharT, class _Traits, class _Allocator>
2664basic_string<_CharT, _Traits, _Allocator>&
2665basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s)
2666{
2667    _LIBCPP_ASSERT(__s != nullptr, "string::append received nullptr");
2668    return append(__s, traits_type::length(__s));
2669}
2670
2671// insert
2672
2673template <class _CharT, class _Traits, class _Allocator>
2674basic_string<_CharT, _Traits, _Allocator>&
2675basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s, size_type __n)
2676{
2677    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::insert received nullptr");
2678    size_type __sz = size();
2679    if (__pos > __sz)
2680        this->__throw_out_of_range();
2681    size_type __cap = capacity();
2682    if (__cap - __sz >= __n)
2683    {
2684        if (__n)
2685        {
2686            value_type* __p = _VSTD::__to_address(__get_pointer());
2687            size_type __n_move = __sz - __pos;
2688            if (__n_move != 0)
2689            {
2690                if (__p + __pos <= __s && __s < __p + __sz)
2691                    __s += __n;
2692                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2693            }
2694            traits_type::move(__p + __pos, __s, __n);
2695            __sz += __n;
2696            __set_size(__sz);
2697            traits_type::assign(__p[__sz], value_type());
2698        }
2699    }
2700    else
2701        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __pos, 0, __n, __s);
2702    return *this;
2703}
2704
2705template <class _CharT, class _Traits, class _Allocator>
2706basic_string<_CharT, _Traits, _Allocator>&
2707basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, size_type __n, value_type __c)
2708{
2709    size_type __sz = size();
2710    if (__pos > __sz)
2711        this->__throw_out_of_range();
2712    if (__n)
2713    {
2714        size_type __cap = capacity();
2715        value_type* __p;
2716        if (__cap - __sz >= __n)
2717        {
2718            __p = _VSTD::__to_address(__get_pointer());
2719            size_type __n_move = __sz - __pos;
2720            if (__n_move != 0)
2721                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2722        }
2723        else
2724        {
2725            __grow_by(__cap, __sz + __n - __cap, __sz, __pos, 0, __n);
2726            __p = _VSTD::__to_address(__get_long_pointer());
2727        }
2728        traits_type::assign(__p + __pos, __n, __c);
2729        __sz += __n;
2730        __set_size(__sz);
2731        traits_type::assign(__p[__sz], value_type());
2732    }
2733    return *this;
2734}
2735
2736template <class _CharT, class _Traits, class _Allocator>
2737template<class _InputIterator>
2738_EnableIf
2739<
2740   __is_exactly_cpp17_input_iterator<_InputIterator>::value
2741        || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
2742   typename basic_string<_CharT, _Traits, _Allocator>::iterator
2743>
2744basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _InputIterator __first, _InputIterator __last)
2745{
2746#if _LIBCPP_DEBUG_LEVEL >= 2
2747    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2748        "string::insert(iterator, range) called with an iterator not"
2749        " referring to this string");
2750#endif
2751    const basic_string __temp(__first, __last, __alloc());
2752    return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2753}
2754
2755template <class _CharT, class _Traits, class _Allocator>
2756template<class _ForwardIterator>
2757_EnableIf
2758<
2759    __is_cpp17_forward_iterator<_ForwardIterator>::value
2760        && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
2761    typename basic_string<_CharT, _Traits, _Allocator>::iterator
2762>
2763basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last)
2764{
2765#if _LIBCPP_DEBUG_LEVEL >= 2
2766    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2767        "string::insert(iterator, range) called with an iterator not"
2768        " referring to this string");
2769#endif
2770    size_type __ip = static_cast<size_type>(__pos - begin());
2771    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2772    if (__n)
2773    {
2774        typedef typename iterator_traits<_ForwardIterator>::reference _CharRef;
2775        _CharRef __tmp_char = *__first;
2776        if (__ptr_in_range(_VSTD::addressof(__tmp_char), data(), data() + size()))
2777        {
2778            const basic_string __temp(__first, __last, __alloc());
2779            return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2780        }
2781
2782        size_type __sz = size();
2783        size_type __cap = capacity();
2784        value_type* __p;
2785        if (__cap - __sz >= __n)
2786        {
2787            __p = _VSTD::__to_address(__get_pointer());
2788            size_type __n_move = __sz - __ip;
2789            if (__n_move != 0)
2790                traits_type::move(__p + __ip + __n, __p + __ip, __n_move);
2791        }
2792        else
2793        {
2794            __grow_by(__cap, __sz + __n - __cap, __sz, __ip, 0, __n);
2795            __p = _VSTD::__to_address(__get_long_pointer());
2796        }
2797        __sz += __n;
2798        __set_size(__sz);
2799        traits_type::assign(__p[__sz], value_type());
2800        for (__p += __ip; __first != __last; ++__p, ++__first)
2801            traits_type::assign(*__p, *__first);
2802    }
2803    return begin() + __ip;
2804}
2805
2806template <class _CharT, class _Traits, class _Allocator>
2807inline
2808basic_string<_CharT, _Traits, _Allocator>&
2809basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str)
2810{
2811    return insert(__pos1, __str.data(), __str.size());
2812}
2813
2814template <class _CharT, class _Traits, class _Allocator>
2815basic_string<_CharT, _Traits, _Allocator>&
2816basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str,
2817                                                  size_type __pos2, size_type __n)
2818{
2819    size_type __str_sz = __str.size();
2820    if (__pos2 > __str_sz)
2821        this->__throw_out_of_range();
2822    return insert(__pos1, __str.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2823}
2824
2825template <class _CharT, class _Traits, class _Allocator>
2826template <class _Tp>
2827_EnableIf
2828<
2829    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2830    basic_string<_CharT, _Traits, _Allocator>&
2831>
2832basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const _Tp& __t,
2833                                                  size_type __pos2, size_type __n)
2834{
2835    __self_view __sv = __t;
2836    size_type __str_sz = __sv.size();
2837    if (__pos2 > __str_sz)
2838        this->__throw_out_of_range();
2839    return insert(__pos1, __sv.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2840}
2841
2842template <class _CharT, class _Traits, class _Allocator>
2843basic_string<_CharT, _Traits, _Allocator>&
2844basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s)
2845{
2846    _LIBCPP_ASSERT(__s != nullptr, "string::insert received nullptr");
2847    return insert(__pos, __s, traits_type::length(__s));
2848}
2849
2850template <class _CharT, class _Traits, class _Allocator>
2851typename basic_string<_CharT, _Traits, _Allocator>::iterator
2852basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, value_type __c)
2853{
2854    size_type __ip = static_cast<size_type>(__pos - begin());
2855    size_type __sz = size();
2856    size_type __cap = capacity();
2857    value_type* __p;
2858    if (__cap == __sz)
2859    {
2860        __grow_by(__cap, 1, __sz, __ip, 0, 1);
2861        __p = _VSTD::__to_address(__get_long_pointer());
2862    }
2863    else
2864    {
2865        __p = _VSTD::__to_address(__get_pointer());
2866        size_type __n_move = __sz - __ip;
2867        if (__n_move != 0)
2868            traits_type::move(__p + __ip + 1, __p + __ip, __n_move);
2869    }
2870    traits_type::assign(__p[__ip], __c);
2871    traits_type::assign(__p[++__sz], value_type());
2872    __set_size(__sz);
2873    return begin() + static_cast<difference_type>(__ip);
2874}
2875
2876template <class _CharT, class _Traits, class _Allocator>
2877inline
2878typename basic_string<_CharT, _Traits, _Allocator>::iterator
2879basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, size_type __n, value_type __c)
2880{
2881#if _LIBCPP_DEBUG_LEVEL >= 2
2882    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2883        "string::insert(iterator, n, value) called with an iterator not"
2884        " referring to this string");
2885#endif
2886    difference_type __p = __pos - begin();
2887    insert(static_cast<size_type>(__p), __n, __c);
2888    return begin() + __p;
2889}
2890
2891// replace
2892
2893template <class _CharT, class _Traits, class _Allocator>
2894basic_string<_CharT, _Traits, _Allocator>&
2895basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2)
2896    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
2897{
2898    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::replace received nullptr");
2899    size_type __sz = size();
2900    if (__pos > __sz)
2901        this->__throw_out_of_range();
2902    __n1 = _VSTD::min(__n1, __sz - __pos);
2903    size_type __cap = capacity();
2904    if (__cap - __sz + __n1 >= __n2)
2905    {
2906        value_type* __p = _VSTD::__to_address(__get_pointer());
2907        if (__n1 != __n2)
2908        {
2909            size_type __n_move = __sz - __pos - __n1;
2910            if (__n_move != 0)
2911            {
2912                if (__n1 > __n2)
2913                {
2914                    traits_type::move(__p + __pos, __s, __n2);
2915                    traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
2916                    goto __finish;
2917                }
2918                if (__p + __pos < __s && __s < __p + __sz)
2919                {
2920                    if (__p + __pos + __n1 <= __s)
2921                        __s += __n2 - __n1;
2922                    else // __p + __pos < __s < __p + __pos + __n1
2923                    {
2924                        traits_type::move(__p + __pos, __s, __n1);
2925                        __pos += __n1;
2926                        __s += __n2;
2927                        __n2 -= __n1;
2928                        __n1 = 0;
2929                    }
2930                }
2931                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
2932            }
2933        }
2934        traits_type::move(__p + __pos, __s, __n2);
2935__finish:
2936// __sz += __n2 - __n1; in this and the below function below can cause unsigned
2937// integer overflow, but this is a safe operation, so we disable the check.
2938        __sz += __n2 - __n1;
2939        __set_size(__sz);
2940        __invalidate_iterators_past(__sz);
2941        traits_type::assign(__p[__sz], value_type());
2942    }
2943    else
2944        __grow_by_and_replace(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2, __s);
2945    return *this;
2946}
2947
2948template <class _CharT, class _Traits, class _Allocator>
2949basic_string<_CharT, _Traits, _Allocator>&
2950basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, size_type __n2, value_type __c)
2951    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
2952{
2953    size_type __sz = size();
2954    if (__pos > __sz)
2955        this->__throw_out_of_range();
2956    __n1 = _VSTD::min(__n1, __sz - __pos);
2957    size_type __cap = capacity();
2958    value_type* __p;
2959    if (__cap - __sz + __n1 >= __n2)
2960    {
2961        __p = _VSTD::__to_address(__get_pointer());
2962        if (__n1 != __n2)
2963        {
2964            size_type __n_move = __sz - __pos - __n1;
2965            if (__n_move != 0)
2966                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
2967        }
2968    }
2969    else
2970    {
2971        __grow_by(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2);
2972        __p = _VSTD::__to_address(__get_long_pointer());
2973    }
2974    traits_type::assign(__p + __pos, __n2, __c);
2975    __sz += __n2 - __n1;
2976    __set_size(__sz);
2977    __invalidate_iterators_past(__sz);
2978    traits_type::assign(__p[__sz], value_type());
2979    return *this;
2980}
2981
2982template <class _CharT, class _Traits, class _Allocator>
2983template<class _InputIterator>
2984_EnableIf
2985<
2986    __is_cpp17_input_iterator<_InputIterator>::value,
2987    basic_string<_CharT, _Traits, _Allocator>&
2988>
2989basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2,
2990                                                   _InputIterator __j1, _InputIterator __j2)
2991{
2992    const basic_string __temp(__j1, __j2, __alloc());
2993    return this->replace(__i1, __i2, __temp);
2994}
2995
2996template <class _CharT, class _Traits, class _Allocator>
2997inline
2998basic_string<_CharT, _Traits, _Allocator>&
2999basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str)
3000{
3001    return replace(__pos1, __n1, __str.data(), __str.size());
3002}
3003
3004template <class _CharT, class _Traits, class _Allocator>
3005basic_string<_CharT, _Traits, _Allocator>&
3006basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str,
3007                                                   size_type __pos2, size_type __n2)
3008{
3009    size_type __str_sz = __str.size();
3010    if (__pos2 > __str_sz)
3011        this->__throw_out_of_range();
3012    return replace(__pos1, __n1, __str.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
3013}
3014
3015template <class _CharT, class _Traits, class _Allocator>
3016template <class _Tp>
3017_EnableIf
3018<
3019    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
3020    basic_string<_CharT, _Traits, _Allocator>&
3021>
3022basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const _Tp& __t,
3023                                                   size_type __pos2, size_type __n2)
3024{
3025    __self_view __sv = __t;
3026    size_type __str_sz = __sv.size();
3027    if (__pos2 > __str_sz)
3028        this->__throw_out_of_range();
3029    return replace(__pos1, __n1, __sv.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
3030}
3031
3032template <class _CharT, class _Traits, class _Allocator>
3033basic_string<_CharT, _Traits, _Allocator>&
3034basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s)
3035{
3036    _LIBCPP_ASSERT(__s != nullptr, "string::replace received nullptr");
3037    return replace(__pos, __n1, __s, traits_type::length(__s));
3038}
3039
3040template <class _CharT, class _Traits, class _Allocator>
3041inline
3042basic_string<_CharT, _Traits, _Allocator>&
3043basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const basic_string& __str)
3044{
3045    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1),
3046                   __str.data(), __str.size());
3047}
3048
3049template <class _CharT, class _Traits, class _Allocator>
3050inline
3051basic_string<_CharT, _Traits, _Allocator>&
3052basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n)
3053{
3054    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s, __n);
3055}
3056
3057template <class _CharT, class _Traits, class _Allocator>
3058inline
3059basic_string<_CharT, _Traits, _Allocator>&
3060basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s)
3061{
3062    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s);
3063}
3064
3065template <class _CharT, class _Traits, class _Allocator>
3066inline
3067basic_string<_CharT, _Traits, _Allocator>&
3068basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c)
3069{
3070    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __n, __c);
3071}
3072
3073// erase
3074
3075// 'externally instantiated' erase() implementation, called when __n != npos.
3076// Does not check __pos against size()
3077template <class _CharT, class _Traits, class _Allocator>
3078void
3079basic_string<_CharT, _Traits, _Allocator>::__erase_external_with_move(
3080    size_type __pos, size_type __n)
3081{
3082    if (__n)
3083    {
3084        size_type __sz = size();
3085        value_type* __p = _VSTD::__to_address(__get_pointer());
3086        __n = _VSTD::min(__n, __sz - __pos);
3087        size_type __n_move = __sz - __pos - __n;
3088        if (__n_move != 0)
3089            traits_type::move(__p + __pos, __p + __pos + __n, __n_move);
3090        __sz -= __n;
3091        __set_size(__sz);
3092        __invalidate_iterators_past(__sz);
3093        traits_type::assign(__p[__sz], value_type());
3094    }
3095}
3096
3097template <class _CharT, class _Traits, class _Allocator>
3098basic_string<_CharT, _Traits, _Allocator>&
3099basic_string<_CharT, _Traits, _Allocator>::erase(size_type __pos,
3100                                                 size_type __n) {
3101  if (__pos > size()) this->__throw_out_of_range();
3102  if (__n == npos) {
3103    __erase_to_end(__pos);
3104  } else {
3105    __erase_external_with_move(__pos, __n);
3106  }
3107  return *this;
3108}
3109
3110template <class _CharT, class _Traits, class _Allocator>
3111inline
3112typename basic_string<_CharT, _Traits, _Allocator>::iterator
3113basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __pos)
3114{
3115#if _LIBCPP_DEBUG_LEVEL >= 2
3116    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
3117        "string::erase(iterator) called with an iterator not"
3118        " referring to this string");
3119#endif
3120    _LIBCPP_ASSERT(__pos != end(),
3121        "string::erase(iterator) called with a non-dereferenceable iterator");
3122    iterator __b = begin();
3123    size_type __r = static_cast<size_type>(__pos - __b);
3124    erase(__r, 1);
3125    return __b + static_cast<difference_type>(__r);
3126}
3127
3128template <class _CharT, class _Traits, class _Allocator>
3129inline
3130typename basic_string<_CharT, _Traits, _Allocator>::iterator
3131basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __first, const_iterator __last)
3132{
3133#if _LIBCPP_DEBUG_LEVEL >= 2
3134    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__first) == this,
3135        "string::erase(iterator,  iterator) called with an iterator not"
3136        " referring to this string");
3137#endif
3138    _LIBCPP_ASSERT(__first <= __last, "string::erase(first, last) called with invalid range");
3139    iterator __b = begin();
3140    size_type __r = static_cast<size_type>(__first - __b);
3141    erase(__r, static_cast<size_type>(__last - __first));
3142    return __b + static_cast<difference_type>(__r);
3143}
3144
3145template <class _CharT, class _Traits, class _Allocator>
3146inline
3147void
3148basic_string<_CharT, _Traits, _Allocator>::pop_back()
3149{
3150    _LIBCPP_ASSERT(!empty(), "string::pop_back(): string is already empty");
3151    size_type __sz;
3152    if (__is_long())
3153    {
3154        __sz = __get_long_size() - 1;
3155        __set_long_size(__sz);
3156        traits_type::assign(*(__get_long_pointer() + __sz), value_type());
3157    }
3158    else
3159    {
3160        __sz = __get_short_size() - 1;
3161        __set_short_size(__sz);
3162        traits_type::assign(*(__get_short_pointer() + __sz), value_type());
3163    }
3164    __invalidate_iterators_past(__sz);
3165}
3166
3167template <class _CharT, class _Traits, class _Allocator>
3168inline
3169void
3170basic_string<_CharT, _Traits, _Allocator>::clear() _NOEXCEPT
3171{
3172    __invalidate_all_iterators();
3173    if (__is_long())
3174    {
3175        traits_type::assign(*__get_long_pointer(), value_type());
3176        __set_long_size(0);
3177    }
3178    else
3179    {
3180        traits_type::assign(*__get_short_pointer(), value_type());
3181        __set_short_size(0);
3182    }
3183}
3184
3185template <class _CharT, class _Traits, class _Allocator>
3186inline
3187void
3188basic_string<_CharT, _Traits, _Allocator>::__erase_to_end(size_type __pos)
3189{
3190    if (__is_long())
3191    {
3192        traits_type::assign(*(__get_long_pointer() + __pos), value_type());
3193        __set_long_size(__pos);
3194    }
3195    else
3196    {
3197        traits_type::assign(*(__get_short_pointer() + __pos), value_type());
3198        __set_short_size(__pos);
3199    }
3200    __invalidate_iterators_past(__pos);
3201}
3202
3203template <class _CharT, class _Traits, class _Allocator>
3204void
3205basic_string<_CharT, _Traits, _Allocator>::resize(size_type __n, value_type __c)
3206{
3207    size_type __sz = size();
3208    if (__n > __sz)
3209        append(__n - __sz, __c);
3210    else
3211        __erase_to_end(__n);
3212}
3213
3214template <class _CharT, class _Traits, class _Allocator>
3215inline void
3216basic_string<_CharT, _Traits, _Allocator>::__resize_default_init(size_type __n)
3217{
3218    size_type __sz = size();
3219    if (__n > __sz) {
3220       __append_default_init(__n - __sz);
3221    } else
3222        __erase_to_end(__n);
3223}
3224
3225template <class _CharT, class _Traits, class _Allocator>
3226inline
3227typename basic_string<_CharT, _Traits, _Allocator>::size_type
3228basic_string<_CharT, _Traits, _Allocator>::max_size() const _NOEXCEPT
3229{
3230    size_type __m = __alloc_traits::max_size(__alloc());
3231#ifdef _LIBCPP_BIG_ENDIAN
3232    return (__m <= ~__long_mask ? __m : __m/2) - __alignment;
3233#else
3234    return __m - __alignment;
3235#endif
3236}
3237
3238template <class _CharT, class _Traits, class _Allocator>
3239void
3240basic_string<_CharT, _Traits, _Allocator>::reserve(size_type __res_arg)
3241{
3242    if (__res_arg > max_size())
3243        this->__throw_length_error();
3244    size_type __cap = capacity();
3245    size_type __sz = size();
3246    __res_arg = _VSTD::max(__res_arg, __sz);
3247    __res_arg = __recommend(__res_arg);
3248    if (__res_arg != __cap)
3249    {
3250        pointer __new_data, __p;
3251        bool __was_long, __now_long;
3252        if (__res_arg == __min_cap - 1)
3253        {
3254            __was_long = true;
3255            __now_long = false;
3256            __new_data = __get_short_pointer();
3257            __p = __get_long_pointer();
3258        }
3259        else
3260        {
3261            if (__res_arg > __cap)
3262                __new_data = __alloc_traits::allocate(__alloc(), __res_arg+1);
3263            else
3264            {
3265            #ifndef _LIBCPP_NO_EXCEPTIONS
3266                try
3267                {
3268            #endif  // _LIBCPP_NO_EXCEPTIONS
3269                    __new_data = __alloc_traits::allocate(__alloc(), __res_arg+1);
3270            #ifndef _LIBCPP_NO_EXCEPTIONS
3271                }
3272                catch (...)
3273                {
3274                    return;
3275                }
3276            #else  // _LIBCPP_NO_EXCEPTIONS
3277                if (__new_data == nullptr)
3278                    return;
3279            #endif  // _LIBCPP_NO_EXCEPTIONS
3280            }
3281            __now_long = true;
3282            __was_long = __is_long();
3283            __p = __get_pointer();
3284        }
3285        traits_type::copy(_VSTD::__to_address(__new_data),
3286                          _VSTD::__to_address(__p), size()+1);
3287        if (__was_long)
3288            __alloc_traits::deallocate(__alloc(), __p, __cap+1);
3289        if (__now_long)
3290        {
3291            __set_long_cap(__res_arg+1);
3292            __set_long_size(__sz);
3293            __set_long_pointer(__new_data);
3294        }
3295        else
3296            __set_short_size(__sz);
3297        __invalidate_all_iterators();
3298    }
3299}
3300
3301template <class _CharT, class _Traits, class _Allocator>
3302inline
3303typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3304basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) const _NOEXCEPT
3305{
3306    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3307    return *(data() + __pos);
3308}
3309
3310template <class _CharT, class _Traits, class _Allocator>
3311inline
3312typename basic_string<_CharT, _Traits, _Allocator>::reference
3313basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) _NOEXCEPT
3314{
3315    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3316    return *(__get_pointer() + __pos);
3317}
3318
3319template <class _CharT, class _Traits, class _Allocator>
3320typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3321basic_string<_CharT, _Traits, _Allocator>::at(size_type __n) const
3322{
3323    if (__n >= size())
3324        this->__throw_out_of_range();
3325    return (*this)[__n];
3326}
3327
3328template <class _CharT, class _Traits, class _Allocator>
3329typename basic_string<_CharT, _Traits, _Allocator>::reference
3330basic_string<_CharT, _Traits, _Allocator>::at(size_type __n)
3331{
3332    if (__n >= size())
3333        this->__throw_out_of_range();
3334    return (*this)[__n];
3335}
3336
3337template <class _CharT, class _Traits, class _Allocator>
3338inline
3339typename basic_string<_CharT, _Traits, _Allocator>::reference
3340basic_string<_CharT, _Traits, _Allocator>::front() _NOEXCEPT
3341{
3342    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3343    return *__get_pointer();
3344}
3345
3346template <class _CharT, class _Traits, class _Allocator>
3347inline
3348typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3349basic_string<_CharT, _Traits, _Allocator>::front() const _NOEXCEPT
3350{
3351    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3352    return *data();
3353}
3354
3355template <class _CharT, class _Traits, class _Allocator>
3356inline
3357typename basic_string<_CharT, _Traits, _Allocator>::reference
3358basic_string<_CharT, _Traits, _Allocator>::back() _NOEXCEPT
3359{
3360    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3361    return *(__get_pointer() + size() - 1);
3362}
3363
3364template <class _CharT, class _Traits, class _Allocator>
3365inline
3366typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3367basic_string<_CharT, _Traits, _Allocator>::back() const _NOEXCEPT
3368{
3369    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3370    return *(data() + size() - 1);
3371}
3372
3373template <class _CharT, class _Traits, class _Allocator>
3374typename basic_string<_CharT, _Traits, _Allocator>::size_type
3375basic_string<_CharT, _Traits, _Allocator>::copy(value_type* __s, size_type __n, size_type __pos) const
3376{
3377    size_type __sz = size();
3378    if (__pos > __sz)
3379        this->__throw_out_of_range();
3380    size_type __rlen = _VSTD::min(__n, __sz - __pos);
3381    traits_type::copy(__s, data() + __pos, __rlen);
3382    return __rlen;
3383}
3384
3385template <class _CharT, class _Traits, class _Allocator>
3386inline
3387basic_string<_CharT, _Traits, _Allocator>
3388basic_string<_CharT, _Traits, _Allocator>::substr(size_type __pos, size_type __n) const
3389{
3390    return basic_string(*this, __pos, __n, __alloc());
3391}
3392
3393template <class _CharT, class _Traits, class _Allocator>
3394inline
3395void
3396basic_string<_CharT, _Traits, _Allocator>::swap(basic_string& __str)
3397#if _LIBCPP_STD_VER >= 14
3398        _NOEXCEPT
3399#else
3400        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
3401                    __is_nothrow_swappable<allocator_type>::value)
3402#endif
3403{
3404#if _LIBCPP_DEBUG_LEVEL >= 2
3405    if (!__is_long())
3406        __get_db()->__invalidate_all(this);
3407    if (!__str.__is_long())
3408        __get_db()->__invalidate_all(&__str);
3409    __get_db()->swap(this, &__str);
3410#endif
3411    _LIBCPP_ASSERT(
3412        __alloc_traits::propagate_on_container_swap::value ||
3413        __alloc_traits::is_always_equal::value ||
3414        __alloc() == __str.__alloc(), "swapping non-equal allocators");
3415    _VSTD::swap(__r_.first(), __str.__r_.first());
3416    __swap_allocator(__alloc(), __str.__alloc());
3417}
3418
3419// find
3420
3421template <class _Traits>
3422struct _LIBCPP_HIDDEN __traits_eq
3423{
3424    typedef typename _Traits::char_type char_type;
3425    _LIBCPP_INLINE_VISIBILITY
3426    bool operator()(const char_type& __x, const char_type& __y) _NOEXCEPT
3427        {return _Traits::eq(__x, __y);}
3428};
3429
3430template<class _CharT, class _Traits, class _Allocator>
3431typename basic_string<_CharT, _Traits, _Allocator>::size_type
3432basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3433                                                size_type __pos,
3434                                                size_type __n) const _NOEXCEPT
3435{
3436    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find(): received nullptr");
3437    return __str_find<value_type, size_type, traits_type, npos>
3438        (data(), size(), __s, __pos, __n);
3439}
3440
3441template<class _CharT, class _Traits, class _Allocator>
3442inline
3443typename basic_string<_CharT, _Traits, _Allocator>::size_type
3444basic_string<_CharT, _Traits, _Allocator>::find(const basic_string& __str,
3445                                                size_type __pos) const _NOEXCEPT
3446{
3447    return __str_find<value_type, size_type, traits_type, npos>
3448        (data(), size(), __str.data(), __pos, __str.size());
3449}
3450
3451template<class _CharT, class _Traits, class _Allocator>
3452template <class _Tp>
3453_EnableIf
3454<
3455    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3456    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3457>
3458basic_string<_CharT, _Traits, _Allocator>::find(const _Tp &__t,
3459                                                size_type __pos) const
3460{
3461    __self_view __sv = __t;
3462    return __str_find<value_type, size_type, traits_type, npos>
3463        (data(), size(), __sv.data(), __pos, __sv.size());
3464}
3465
3466template<class _CharT, class _Traits, class _Allocator>
3467inline
3468typename basic_string<_CharT, _Traits, _Allocator>::size_type
3469basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3470                                                size_type __pos) const _NOEXCEPT
3471{
3472    _LIBCPP_ASSERT(__s != nullptr, "string::find(): received nullptr");
3473    return __str_find<value_type, size_type, traits_type, npos>
3474        (data(), size(), __s, __pos, traits_type::length(__s));
3475}
3476
3477template<class _CharT, class _Traits, class _Allocator>
3478typename basic_string<_CharT, _Traits, _Allocator>::size_type
3479basic_string<_CharT, _Traits, _Allocator>::find(value_type __c,
3480                                                size_type __pos) const _NOEXCEPT
3481{
3482    return __str_find<value_type, size_type, traits_type, npos>
3483        (data(), size(), __c, __pos);
3484}
3485
3486// rfind
3487
3488template<class _CharT, class _Traits, class _Allocator>
3489typename basic_string<_CharT, _Traits, _Allocator>::size_type
3490basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3491                                                 size_type __pos,
3492                                                 size_type __n) const _NOEXCEPT
3493{
3494    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::rfind(): received nullptr");
3495    return __str_rfind<value_type, size_type, traits_type, npos>
3496        (data(), size(), __s, __pos, __n);
3497}
3498
3499template<class _CharT, class _Traits, class _Allocator>
3500inline
3501typename basic_string<_CharT, _Traits, _Allocator>::size_type
3502basic_string<_CharT, _Traits, _Allocator>::rfind(const basic_string& __str,
3503                                                 size_type __pos) const _NOEXCEPT
3504{
3505    return __str_rfind<value_type, size_type, traits_type, npos>
3506        (data(), size(), __str.data(), __pos, __str.size());
3507}
3508
3509template<class _CharT, class _Traits, class _Allocator>
3510template <class _Tp>
3511_EnableIf
3512<
3513    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3514    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3515>
3516basic_string<_CharT, _Traits, _Allocator>::rfind(const _Tp& __t,
3517                                                size_type __pos) const
3518{
3519    __self_view __sv = __t;
3520    return __str_rfind<value_type, size_type, traits_type, npos>
3521        (data(), size(), __sv.data(), __pos, __sv.size());
3522}
3523
3524template<class _CharT, class _Traits, class _Allocator>
3525inline
3526typename basic_string<_CharT, _Traits, _Allocator>::size_type
3527basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3528                                                 size_type __pos) const _NOEXCEPT
3529{
3530    _LIBCPP_ASSERT(__s != nullptr, "string::rfind(): received nullptr");
3531    return __str_rfind<value_type, size_type, traits_type, npos>
3532        (data(), size(), __s, __pos, traits_type::length(__s));
3533}
3534
3535template<class _CharT, class _Traits, class _Allocator>
3536typename basic_string<_CharT, _Traits, _Allocator>::size_type
3537basic_string<_CharT, _Traits, _Allocator>::rfind(value_type __c,
3538                                                 size_type __pos) const _NOEXCEPT
3539{
3540    return __str_rfind<value_type, size_type, traits_type, npos>
3541        (data(), size(), __c, __pos);
3542}
3543
3544// find_first_of
3545
3546template<class _CharT, class _Traits, class _Allocator>
3547typename basic_string<_CharT, _Traits, _Allocator>::size_type
3548basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3549                                                         size_type __pos,
3550                                                         size_type __n) const _NOEXCEPT
3551{
3552    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_of(): received nullptr");
3553    return __str_find_first_of<value_type, size_type, traits_type, npos>
3554        (data(), size(), __s, __pos, __n);
3555}
3556
3557template<class _CharT, class _Traits, class _Allocator>
3558inline
3559typename basic_string<_CharT, _Traits, _Allocator>::size_type
3560basic_string<_CharT, _Traits, _Allocator>::find_first_of(const basic_string& __str,
3561                                                         size_type __pos) const _NOEXCEPT
3562{
3563    return __str_find_first_of<value_type, size_type, traits_type, npos>
3564        (data(), size(), __str.data(), __pos, __str.size());
3565}
3566
3567template<class _CharT, class _Traits, class _Allocator>
3568template <class _Tp>
3569_EnableIf
3570<
3571    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3572    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3573>
3574basic_string<_CharT, _Traits, _Allocator>::find_first_of(const _Tp& __t,
3575                                                size_type __pos) const
3576{
3577    __self_view __sv = __t;
3578    return __str_find_first_of<value_type, size_type, traits_type, npos>
3579        (data(), size(), __sv.data(), __pos, __sv.size());
3580}
3581
3582template<class _CharT, class _Traits, class _Allocator>
3583inline
3584typename basic_string<_CharT, _Traits, _Allocator>::size_type
3585basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3586                                                         size_type __pos) const _NOEXCEPT
3587{
3588    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_of(): received nullptr");
3589    return __str_find_first_of<value_type, size_type, traits_type, npos>
3590        (data(), size(), __s, __pos, traits_type::length(__s));
3591}
3592
3593template<class _CharT, class _Traits, class _Allocator>
3594inline
3595typename basic_string<_CharT, _Traits, _Allocator>::size_type
3596basic_string<_CharT, _Traits, _Allocator>::find_first_of(value_type __c,
3597                                                         size_type __pos) const _NOEXCEPT
3598{
3599    return find(__c, __pos);
3600}
3601
3602// find_last_of
3603
3604template<class _CharT, class _Traits, class _Allocator>
3605typename basic_string<_CharT, _Traits, _Allocator>::size_type
3606basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3607                                                        size_type __pos,
3608                                                        size_type __n) const _NOEXCEPT
3609{
3610    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_of(): received nullptr");
3611    return __str_find_last_of<value_type, size_type, traits_type, npos>
3612        (data(), size(), __s, __pos, __n);
3613}
3614
3615template<class _CharT, class _Traits, class _Allocator>
3616inline
3617typename basic_string<_CharT, _Traits, _Allocator>::size_type
3618basic_string<_CharT, _Traits, _Allocator>::find_last_of(const basic_string& __str,
3619                                                        size_type __pos) const _NOEXCEPT
3620{
3621    return __str_find_last_of<value_type, size_type, traits_type, npos>
3622        (data(), size(), __str.data(), __pos, __str.size());
3623}
3624
3625template<class _CharT, class _Traits, class _Allocator>
3626template <class _Tp>
3627_EnableIf
3628<
3629    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3630    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3631>
3632basic_string<_CharT, _Traits, _Allocator>::find_last_of(const _Tp& __t,
3633                                                size_type __pos) const
3634{
3635    __self_view __sv = __t;
3636    return __str_find_last_of<value_type, size_type, traits_type, npos>
3637        (data(), size(), __sv.data(), __pos, __sv.size());
3638}
3639
3640template<class _CharT, class _Traits, class _Allocator>
3641inline
3642typename basic_string<_CharT, _Traits, _Allocator>::size_type
3643basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3644                                                        size_type __pos) const _NOEXCEPT
3645{
3646    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_of(): received nullptr");
3647    return __str_find_last_of<value_type, size_type, traits_type, npos>
3648        (data(), size(), __s, __pos, traits_type::length(__s));
3649}
3650
3651template<class _CharT, class _Traits, class _Allocator>
3652inline
3653typename basic_string<_CharT, _Traits, _Allocator>::size_type
3654basic_string<_CharT, _Traits, _Allocator>::find_last_of(value_type __c,
3655                                                        size_type __pos) const _NOEXCEPT
3656{
3657    return rfind(__c, __pos);
3658}
3659
3660// find_first_not_of
3661
3662template<class _CharT, class _Traits, class _Allocator>
3663typename basic_string<_CharT, _Traits, _Allocator>::size_type
3664basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3665                                                             size_type __pos,
3666                                                             size_type __n) const _NOEXCEPT
3667{
3668    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_not_of(): received nullptr");
3669    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3670        (data(), size(), __s, __pos, __n);
3671}
3672
3673template<class _CharT, class _Traits, class _Allocator>
3674inline
3675typename basic_string<_CharT, _Traits, _Allocator>::size_type
3676basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const basic_string& __str,
3677                                                             size_type __pos) const _NOEXCEPT
3678{
3679    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3680        (data(), size(), __str.data(), __pos, __str.size());
3681}
3682
3683template<class _CharT, class _Traits, class _Allocator>
3684template <class _Tp>
3685_EnableIf
3686<
3687    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3688    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3689>
3690basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const _Tp& __t,
3691                                                size_type __pos) const
3692{
3693    __self_view __sv = __t;
3694    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3695        (data(), size(), __sv.data(), __pos, __sv.size());
3696}
3697
3698template<class _CharT, class _Traits, class _Allocator>
3699inline
3700typename basic_string<_CharT, _Traits, _Allocator>::size_type
3701basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3702                                                             size_type __pos) const _NOEXCEPT
3703{
3704    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_not_of(): received nullptr");
3705    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3706        (data(), size(), __s, __pos, traits_type::length(__s));
3707}
3708
3709template<class _CharT, class _Traits, class _Allocator>
3710inline
3711typename basic_string<_CharT, _Traits, _Allocator>::size_type
3712basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(value_type __c,
3713                                                             size_type __pos) const _NOEXCEPT
3714{
3715    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3716        (data(), size(), __c, __pos);
3717}
3718
3719// find_last_not_of
3720
3721template<class _CharT, class _Traits, class _Allocator>
3722typename basic_string<_CharT, _Traits, _Allocator>::size_type
3723basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3724                                                            size_type __pos,
3725                                                            size_type __n) const _NOEXCEPT
3726{
3727    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_not_of(): received nullptr");
3728    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3729        (data(), size(), __s, __pos, __n);
3730}
3731
3732template<class _CharT, class _Traits, class _Allocator>
3733inline
3734typename basic_string<_CharT, _Traits, _Allocator>::size_type
3735basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const basic_string& __str,
3736                                                            size_type __pos) const _NOEXCEPT
3737{
3738    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3739        (data(), size(), __str.data(), __pos, __str.size());
3740}
3741
3742template<class _CharT, class _Traits, class _Allocator>
3743template <class _Tp>
3744_EnableIf
3745<
3746    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3747    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3748>
3749basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const _Tp& __t,
3750                                                size_type __pos) const
3751{
3752    __self_view __sv = __t;
3753    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3754        (data(), size(), __sv.data(), __pos, __sv.size());
3755}
3756
3757template<class _CharT, class _Traits, class _Allocator>
3758inline
3759typename basic_string<_CharT, _Traits, _Allocator>::size_type
3760basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3761                                                            size_type __pos) const _NOEXCEPT
3762{
3763    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_not_of(): received nullptr");
3764    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3765        (data(), size(), __s, __pos, traits_type::length(__s));
3766}
3767
3768template<class _CharT, class _Traits, class _Allocator>
3769inline
3770typename basic_string<_CharT, _Traits, _Allocator>::size_type
3771basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(value_type __c,
3772                                                            size_type __pos) const _NOEXCEPT
3773{
3774    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3775        (data(), size(), __c, __pos);
3776}
3777
3778// compare
3779
3780template <class _CharT, class _Traits, class _Allocator>
3781template <class _Tp>
3782_EnableIf
3783<
3784    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3785    int
3786>
3787basic_string<_CharT, _Traits, _Allocator>::compare(const _Tp& __t) const
3788{
3789    __self_view __sv = __t;
3790    size_t __lhs_sz = size();
3791    size_t __rhs_sz = __sv.size();
3792    int __result = traits_type::compare(data(), __sv.data(),
3793                                        _VSTD::min(__lhs_sz, __rhs_sz));
3794    if (__result != 0)
3795        return __result;
3796    if (__lhs_sz < __rhs_sz)
3797        return -1;
3798    if (__lhs_sz > __rhs_sz)
3799        return 1;
3800    return 0;
3801}
3802
3803template <class _CharT, class _Traits, class _Allocator>
3804inline
3805int
3806basic_string<_CharT, _Traits, _Allocator>::compare(const basic_string& __str) const _NOEXCEPT
3807{
3808    return compare(__self_view(__str));
3809}
3810
3811template <class _CharT, class _Traits, class _Allocator>
3812int
3813basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3814                                                   size_type __n1,
3815                                                   const value_type* __s,
3816                                                   size_type __n2) const
3817{
3818    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::compare(): received nullptr");
3819    size_type __sz = size();
3820    if (__pos1 > __sz || __n2 == npos)
3821        this->__throw_out_of_range();
3822    size_type __rlen = _VSTD::min(__n1, __sz - __pos1);
3823    int __r = traits_type::compare(data() + __pos1, __s, _VSTD::min(__rlen, __n2));
3824    if (__r == 0)
3825    {
3826        if (__rlen < __n2)
3827            __r = -1;
3828        else if (__rlen > __n2)
3829            __r = 1;
3830    }
3831    return __r;
3832}
3833
3834template <class _CharT, class _Traits, class _Allocator>
3835template <class _Tp>
3836_EnableIf
3837<
3838    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3839    int
3840>
3841basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3842                                                   size_type __n1,
3843                                                   const _Tp& __t) const
3844{
3845    __self_view __sv = __t;
3846    return compare(__pos1, __n1, __sv.data(), __sv.size());
3847}
3848
3849template <class _CharT, class _Traits, class _Allocator>
3850inline
3851int
3852basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3853                                                   size_type __n1,
3854                                                   const basic_string& __str) const
3855{
3856    return compare(__pos1, __n1, __str.data(), __str.size());
3857}
3858
3859template <class _CharT, class _Traits, class _Allocator>
3860template <class _Tp>
3861_EnableIf
3862<
3863    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
3864    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
3865    int
3866>
3867basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3868                                                   size_type __n1,
3869                                                   const _Tp& __t,
3870                                                   size_type __pos2,
3871                                                   size_type __n2) const
3872{
3873    __self_view __sv = __t;
3874    return __self_view(*this).substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
3875}
3876
3877template <class _CharT, class _Traits, class _Allocator>
3878int
3879basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3880                                                   size_type __n1,
3881                                                   const basic_string& __str,
3882                                                   size_type __pos2,
3883                                                   size_type __n2) const
3884{
3885        return compare(__pos1, __n1, __self_view(__str), __pos2, __n2);
3886}
3887
3888template <class _CharT, class _Traits, class _Allocator>
3889int
3890basic_string<_CharT, _Traits, _Allocator>::compare(const value_type* __s) const _NOEXCEPT
3891{
3892    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3893    return compare(0, npos, __s, traits_type::length(__s));
3894}
3895
3896template <class _CharT, class _Traits, class _Allocator>
3897int
3898basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3899                                                   size_type __n1,
3900                                                   const value_type* __s) const
3901{
3902    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3903    return compare(__pos1, __n1, __s, traits_type::length(__s));
3904}
3905
3906// __invariants
3907
3908template<class _CharT, class _Traits, class _Allocator>
3909inline
3910bool
3911basic_string<_CharT, _Traits, _Allocator>::__invariants() const
3912{
3913    if (size() > capacity())
3914        return false;
3915    if (capacity() < __min_cap - 1)
3916        return false;
3917    if (data() == 0)
3918        return false;
3919    if (data()[size()] != value_type(0))
3920        return false;
3921    return true;
3922}
3923
3924// __clear_and_shrink
3925
3926template<class _CharT, class _Traits, class _Allocator>
3927inline
3928void
3929basic_string<_CharT, _Traits, _Allocator>::__clear_and_shrink() _NOEXCEPT
3930{
3931    clear();
3932    if(__is_long())
3933    {
3934        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), capacity() + 1);
3935        __set_long_cap(0);
3936        __set_short_size(0);
3937    }
3938}
3939
3940// operator==
3941
3942template<class _CharT, class _Traits, class _Allocator>
3943inline _LIBCPP_INLINE_VISIBILITY
3944bool
3945operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
3946           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3947{
3948    size_t __lhs_sz = __lhs.size();
3949    return __lhs_sz == __rhs.size() && _Traits::compare(__lhs.data(),
3950                                                        __rhs.data(),
3951                                                        __lhs_sz) == 0;
3952}
3953
3954template<class _Allocator>
3955inline _LIBCPP_INLINE_VISIBILITY
3956bool
3957operator==(const basic_string<char, char_traits<char>, _Allocator>& __lhs,
3958           const basic_string<char, char_traits<char>, _Allocator>& __rhs) _NOEXCEPT
3959{
3960    size_t __lhs_sz = __lhs.size();
3961    if (__lhs_sz != __rhs.size())
3962        return false;
3963    const char* __lp = __lhs.data();
3964    const char* __rp = __rhs.data();
3965    if (__lhs.__is_long())
3966        return char_traits<char>::compare(__lp, __rp, __lhs_sz) == 0;
3967    for (; __lhs_sz != 0; --__lhs_sz, ++__lp, ++__rp)
3968        if (*__lp != *__rp)
3969            return false;
3970    return true;
3971}
3972
3973template<class _CharT, class _Traits, class _Allocator>
3974inline _LIBCPP_INLINE_VISIBILITY
3975bool
3976operator==(const _CharT* __lhs,
3977           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
3978{
3979    typedef basic_string<_CharT, _Traits, _Allocator> _String;
3980    _LIBCPP_ASSERT(__lhs != nullptr, "operator==(char*, basic_string): received nullptr");
3981    size_t __lhs_len = _Traits::length(__lhs);
3982    if (__lhs_len != __rhs.size()) return false;
3983    return __rhs.compare(0, _String::npos, __lhs, __lhs_len) == 0;
3984}
3985
3986template<class _CharT, class _Traits, class _Allocator>
3987inline _LIBCPP_INLINE_VISIBILITY
3988bool
3989operator==(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
3990           const _CharT* __rhs) _NOEXCEPT
3991{
3992    typedef basic_string<_CharT, _Traits, _Allocator> _String;
3993    _LIBCPP_ASSERT(__rhs != nullptr, "operator==(basic_string, char*): received nullptr");
3994    size_t __rhs_len = _Traits::length(__rhs);
3995    if (__rhs_len != __lhs.size()) return false;
3996    return __lhs.compare(0, _String::npos, __rhs, __rhs_len) == 0;
3997}
3998
3999template<class _CharT, class _Traits, class _Allocator>
4000inline _LIBCPP_INLINE_VISIBILITY
4001bool
4002operator!=(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
4003           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4004{
4005    return !(__lhs == __rhs);
4006}
4007
4008template<class _CharT, class _Traits, class _Allocator>
4009inline _LIBCPP_INLINE_VISIBILITY
4010bool
4011operator!=(const _CharT* __lhs,
4012           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4013{
4014    return !(__lhs == __rhs);
4015}
4016
4017template<class _CharT, class _Traits, class _Allocator>
4018inline _LIBCPP_INLINE_VISIBILITY
4019bool
4020operator!=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4021           const _CharT* __rhs) _NOEXCEPT
4022{
4023    return !(__lhs == __rhs);
4024}
4025
4026// operator<
4027
4028template<class _CharT, class _Traits, class _Allocator>
4029inline _LIBCPP_INLINE_VISIBILITY
4030bool
4031operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4032           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4033{
4034    return __lhs.compare(__rhs) < 0;
4035}
4036
4037template<class _CharT, class _Traits, class _Allocator>
4038inline _LIBCPP_INLINE_VISIBILITY
4039bool
4040operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4041           const _CharT* __rhs) _NOEXCEPT
4042{
4043    return __lhs.compare(__rhs) < 0;
4044}
4045
4046template<class _CharT, class _Traits, class _Allocator>
4047inline _LIBCPP_INLINE_VISIBILITY
4048bool
4049operator< (const _CharT* __lhs,
4050           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4051{
4052    return __rhs.compare(__lhs) > 0;
4053}
4054
4055// operator>
4056
4057template<class _CharT, class _Traits, class _Allocator>
4058inline _LIBCPP_INLINE_VISIBILITY
4059bool
4060operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4061           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4062{
4063    return __rhs < __lhs;
4064}
4065
4066template<class _CharT, class _Traits, class _Allocator>
4067inline _LIBCPP_INLINE_VISIBILITY
4068bool
4069operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4070           const _CharT* __rhs) _NOEXCEPT
4071{
4072    return __rhs < __lhs;
4073}
4074
4075template<class _CharT, class _Traits, class _Allocator>
4076inline _LIBCPP_INLINE_VISIBILITY
4077bool
4078operator> (const _CharT* __lhs,
4079           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4080{
4081    return __rhs < __lhs;
4082}
4083
4084// operator<=
4085
4086template<class _CharT, class _Traits, class _Allocator>
4087inline _LIBCPP_INLINE_VISIBILITY
4088bool
4089operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4090           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4091{
4092    return !(__rhs < __lhs);
4093}
4094
4095template<class _CharT, class _Traits, class _Allocator>
4096inline _LIBCPP_INLINE_VISIBILITY
4097bool
4098operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4099           const _CharT* __rhs) _NOEXCEPT
4100{
4101    return !(__rhs < __lhs);
4102}
4103
4104template<class _CharT, class _Traits, class _Allocator>
4105inline _LIBCPP_INLINE_VISIBILITY
4106bool
4107operator<=(const _CharT* __lhs,
4108           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4109{
4110    return !(__rhs < __lhs);
4111}
4112
4113// operator>=
4114
4115template<class _CharT, class _Traits, class _Allocator>
4116inline _LIBCPP_INLINE_VISIBILITY
4117bool
4118operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4119           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4120{
4121    return !(__lhs < __rhs);
4122}
4123
4124template<class _CharT, class _Traits, class _Allocator>
4125inline _LIBCPP_INLINE_VISIBILITY
4126bool
4127operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4128           const _CharT* __rhs) _NOEXCEPT
4129{
4130    return !(__lhs < __rhs);
4131}
4132
4133template<class _CharT, class _Traits, class _Allocator>
4134inline _LIBCPP_INLINE_VISIBILITY
4135bool
4136operator>=(const _CharT* __lhs,
4137           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4138{
4139    return !(__lhs < __rhs);
4140}
4141
4142// operator +
4143
4144template<class _CharT, class _Traits, class _Allocator>
4145basic_string<_CharT, _Traits, _Allocator>
4146operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4147          const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4148{
4149    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4150    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4151    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4152    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4153    __r.append(__rhs.data(), __rhs_sz);
4154    return __r;
4155}
4156
4157template<class _CharT, class _Traits, class _Allocator>
4158basic_string<_CharT, _Traits, _Allocator>
4159operator+(const _CharT* __lhs , const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4160{
4161    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4162    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = _Traits::length(__lhs);
4163    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4164    __r.__init(__lhs, __lhs_sz, __lhs_sz + __rhs_sz);
4165    __r.append(__rhs.data(), __rhs_sz);
4166    return __r;
4167}
4168
4169template<class _CharT, class _Traits, class _Allocator>
4170basic_string<_CharT, _Traits, _Allocator>
4171operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4172{
4173    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4174    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4175    __r.__init(&__lhs, 1, 1 + __rhs_sz);
4176    __r.append(__rhs.data(), __rhs_sz);
4177    return __r;
4178}
4179
4180template<class _CharT, class _Traits, class _Allocator>
4181inline
4182basic_string<_CharT, _Traits, _Allocator>
4183operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs)
4184{
4185    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4186    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4187    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = _Traits::length(__rhs);
4188    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4189    __r.append(__rhs, __rhs_sz);
4190    return __r;
4191}
4192
4193template<class _CharT, class _Traits, class _Allocator>
4194basic_string<_CharT, _Traits, _Allocator>
4195operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, _CharT __rhs)
4196{
4197    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4198    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4199    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + 1);
4200    __r.push_back(__rhs);
4201    return __r;
4202}
4203
4204#ifndef _LIBCPP_CXX03_LANG
4205
4206template<class _CharT, class _Traits, class _Allocator>
4207inline _LIBCPP_INLINE_VISIBILITY
4208basic_string<_CharT, _Traits, _Allocator>
4209operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4210{
4211    return _VSTD::move(__lhs.append(__rhs));
4212}
4213
4214template<class _CharT, class _Traits, class _Allocator>
4215inline _LIBCPP_INLINE_VISIBILITY
4216basic_string<_CharT, _Traits, _Allocator>
4217operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4218{
4219    return _VSTD::move(__rhs.insert(0, __lhs));
4220}
4221
4222template<class _CharT, class _Traits, class _Allocator>
4223inline _LIBCPP_INLINE_VISIBILITY
4224basic_string<_CharT, _Traits, _Allocator>
4225operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4226{
4227    return _VSTD::move(__lhs.append(__rhs));
4228}
4229
4230template<class _CharT, class _Traits, class _Allocator>
4231inline _LIBCPP_INLINE_VISIBILITY
4232basic_string<_CharT, _Traits, _Allocator>
4233operator+(const _CharT* __lhs , basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4234{
4235    return _VSTD::move(__rhs.insert(0, __lhs));
4236}
4237
4238template<class _CharT, class _Traits, class _Allocator>
4239inline _LIBCPP_INLINE_VISIBILITY
4240basic_string<_CharT, _Traits, _Allocator>
4241operator+(_CharT __lhs, basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4242{
4243    __rhs.insert(__rhs.begin(), __lhs);
4244    return _VSTD::move(__rhs);
4245}
4246
4247template<class _CharT, class _Traits, class _Allocator>
4248inline _LIBCPP_INLINE_VISIBILITY
4249basic_string<_CharT, _Traits, _Allocator>
4250operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const _CharT* __rhs)
4251{
4252    return _VSTD::move(__lhs.append(__rhs));
4253}
4254
4255template<class _CharT, class _Traits, class _Allocator>
4256inline _LIBCPP_INLINE_VISIBILITY
4257basic_string<_CharT, _Traits, _Allocator>
4258operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, _CharT __rhs)
4259{
4260    __lhs.push_back(__rhs);
4261    return _VSTD::move(__lhs);
4262}
4263
4264#endif  // _LIBCPP_CXX03_LANG
4265
4266// swap
4267
4268template<class _CharT, class _Traits, class _Allocator>
4269inline _LIBCPP_INLINE_VISIBILITY
4270void
4271swap(basic_string<_CharT, _Traits, _Allocator>& __lhs,
4272     basic_string<_CharT, _Traits, _Allocator>& __rhs)
4273     _NOEXCEPT_(_NOEXCEPT_(__lhs.swap(__rhs)))
4274{
4275    __lhs.swap(__rhs);
4276}
4277
4278#ifndef _LIBCPP_NO_HAS_CHAR8_T
4279typedef basic_string<char8_t> u8string;
4280#endif
4281
4282#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
4283typedef basic_string<char16_t> u16string;
4284typedef basic_string<char32_t> u32string;
4285#endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
4286
4287_LIBCPP_FUNC_VIS int                stoi  (const string& __str, size_t* __idx = 0, int __base = 10);
4288_LIBCPP_FUNC_VIS long               stol  (const string& __str, size_t* __idx = 0, int __base = 10);
4289_LIBCPP_FUNC_VIS unsigned long      stoul (const string& __str, size_t* __idx = 0, int __base = 10);
4290_LIBCPP_FUNC_VIS long long          stoll (const string& __str, size_t* __idx = 0, int __base = 10);
4291_LIBCPP_FUNC_VIS unsigned long long stoull(const string& __str, size_t* __idx = 0, int __base = 10);
4292
4293_LIBCPP_FUNC_VIS float       stof (const string& __str, size_t* __idx = 0);
4294_LIBCPP_FUNC_VIS double      stod (const string& __str, size_t* __idx = 0);
4295_LIBCPP_FUNC_VIS long double stold(const string& __str, size_t* __idx = 0);
4296
4297_LIBCPP_FUNC_VIS string to_string(int __val);
4298_LIBCPP_FUNC_VIS string to_string(unsigned __val);
4299_LIBCPP_FUNC_VIS string to_string(long __val);
4300_LIBCPP_FUNC_VIS string to_string(unsigned long __val);
4301_LIBCPP_FUNC_VIS string to_string(long long __val);
4302_LIBCPP_FUNC_VIS string to_string(unsigned long long __val);
4303_LIBCPP_FUNC_VIS string to_string(float __val);
4304_LIBCPP_FUNC_VIS string to_string(double __val);
4305_LIBCPP_FUNC_VIS string to_string(long double __val);
4306
4307_LIBCPP_FUNC_VIS int                stoi  (const wstring& __str, size_t* __idx = 0, int __base = 10);
4308_LIBCPP_FUNC_VIS long               stol  (const wstring& __str, size_t* __idx = 0, int __base = 10);
4309_LIBCPP_FUNC_VIS unsigned long      stoul (const wstring& __str, size_t* __idx = 0, int __base = 10);
4310_LIBCPP_FUNC_VIS long long          stoll (const wstring& __str, size_t* __idx = 0, int __base = 10);
4311_LIBCPP_FUNC_VIS unsigned long long stoull(const wstring& __str, size_t* __idx = 0, int __base = 10);
4312
4313_LIBCPP_FUNC_VIS float       stof (const wstring& __str, size_t* __idx = 0);
4314_LIBCPP_FUNC_VIS double      stod (const wstring& __str, size_t* __idx = 0);
4315_LIBCPP_FUNC_VIS long double stold(const wstring& __str, size_t* __idx = 0);
4316
4317_LIBCPP_FUNC_VIS wstring to_wstring(int __val);
4318_LIBCPP_FUNC_VIS wstring to_wstring(unsigned __val);
4319_LIBCPP_FUNC_VIS wstring to_wstring(long __val);
4320_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long __val);
4321_LIBCPP_FUNC_VIS wstring to_wstring(long long __val);
4322_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long long __val);
4323_LIBCPP_FUNC_VIS wstring to_wstring(float __val);
4324_LIBCPP_FUNC_VIS wstring to_wstring(double __val);
4325_LIBCPP_FUNC_VIS wstring to_wstring(long double __val);
4326
4327template<class _CharT, class _Traits, class _Allocator>
4328_LIBCPP_FUNC_VIS
4329const typename basic_string<_CharT, _Traits, _Allocator>::size_type
4330               basic_string<_CharT, _Traits, _Allocator>::npos;
4331
4332template <class _CharT, class _Allocator>
4333struct _LIBCPP_TEMPLATE_VIS
4334    hash<basic_string<_CharT, char_traits<_CharT>, _Allocator> >
4335    : public unary_function<
4336          basic_string<_CharT, char_traits<_CharT>, _Allocator>, size_t>
4337{
4338    size_t
4339    operator()(const basic_string<_CharT, char_traits<_CharT>, _Allocator>& __val) const _NOEXCEPT
4340    { return __do_string_hash(__val.data(), __val.data() + __val.size()); }
4341};
4342
4343
4344template<class _CharT, class _Traits, class _Allocator>
4345basic_ostream<_CharT, _Traits>&
4346operator<<(basic_ostream<_CharT, _Traits>& __os,
4347           const basic_string<_CharT, _Traits, _Allocator>& __str);
4348
4349template<class _CharT, class _Traits, class _Allocator>
4350basic_istream<_CharT, _Traits>&
4351operator>>(basic_istream<_CharT, _Traits>& __is,
4352           basic_string<_CharT, _Traits, _Allocator>& __str);
4353
4354template<class _CharT, class _Traits, class _Allocator>
4355basic_istream<_CharT, _Traits>&
4356getline(basic_istream<_CharT, _Traits>& __is,
4357        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4358
4359template<class _CharT, class _Traits, class _Allocator>
4360inline _LIBCPP_INLINE_VISIBILITY
4361basic_istream<_CharT, _Traits>&
4362getline(basic_istream<_CharT, _Traits>& __is,
4363        basic_string<_CharT, _Traits, _Allocator>& __str);
4364
4365#ifndef _LIBCPP_CXX03_LANG
4366
4367template<class _CharT, class _Traits, class _Allocator>
4368inline _LIBCPP_INLINE_VISIBILITY
4369basic_istream<_CharT, _Traits>&
4370getline(basic_istream<_CharT, _Traits>&& __is,
4371        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4372
4373template<class _CharT, class _Traits, class _Allocator>
4374inline _LIBCPP_INLINE_VISIBILITY
4375basic_istream<_CharT, _Traits>&
4376getline(basic_istream<_CharT, _Traits>&& __is,
4377        basic_string<_CharT, _Traits, _Allocator>& __str);
4378
4379#endif  // _LIBCPP_CXX03_LANG
4380
4381#if _LIBCPP_STD_VER > 17
4382template<class _CharT, class _Traits, class _Allocator, class _Up>
4383inline _LIBCPP_INLINE_VISIBILITY
4384void erase(basic_string<_CharT, _Traits, _Allocator>& __str, const _Up& __v)
4385{ __str.erase(_VSTD::remove(__str.begin(), __str.end(), __v), __str.end()); }
4386
4387template<class _CharT, class _Traits, class _Allocator, class _Predicate>
4388inline _LIBCPP_INLINE_VISIBILITY
4389void erase_if(basic_string<_CharT, _Traits, _Allocator>& __str, _Predicate __pred)
4390{ __str.erase(_VSTD::remove_if(__str.begin(), __str.end(), __pred), __str.end()); }
4391#endif
4392
4393#if _LIBCPP_DEBUG_LEVEL >= 2
4394
4395template<class _CharT, class _Traits, class _Allocator>
4396bool
4397basic_string<_CharT, _Traits, _Allocator>::__dereferenceable(const const_iterator* __i) const
4398{
4399    return this->data() <= _VSTD::__to_address(__i->base()) &&
4400           _VSTD::__to_address(__i->base()) < this->data() + this->size();
4401}
4402
4403template<class _CharT, class _Traits, class _Allocator>
4404bool
4405basic_string<_CharT, _Traits, _Allocator>::__decrementable(const const_iterator* __i) const
4406{
4407    return this->data() < _VSTD::__to_address(__i->base()) &&
4408           _VSTD::__to_address(__i->base()) <= this->data() + this->size();
4409}
4410
4411template<class _CharT, class _Traits, class _Allocator>
4412bool
4413basic_string<_CharT, _Traits, _Allocator>::__addable(const const_iterator* __i, ptrdiff_t __n) const
4414{
4415    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4416    return this->data() <= __p && __p <= this->data() + this->size();
4417}
4418
4419template<class _CharT, class _Traits, class _Allocator>
4420bool
4421basic_string<_CharT, _Traits, _Allocator>::__subscriptable(const const_iterator* __i, ptrdiff_t __n) const
4422{
4423    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4424    return this->data() <= __p && __p < this->data() + this->size();
4425}
4426
4427#endif  // _LIBCPP_DEBUG_LEVEL >= 2
4428
4429#if _LIBCPP_STD_VER > 11
4430// Literal suffixes for basic_string [basic.string.literals]
4431inline namespace literals
4432{
4433  inline namespace string_literals
4434  {
4435    inline _LIBCPP_INLINE_VISIBILITY
4436    basic_string<char> operator "" s( const char *__str, size_t __len )
4437    {
4438        return basic_string<char> (__str, __len);
4439    }
4440
4441    inline _LIBCPP_INLINE_VISIBILITY
4442    basic_string<wchar_t> operator "" s( const wchar_t *__str, size_t __len )
4443    {
4444        return basic_string<wchar_t> (__str, __len);
4445    }
4446
4447#ifndef _LIBCPP_NO_HAS_CHAR8_T
4448    inline _LIBCPP_INLINE_VISIBILITY
4449    basic_string<char8_t> operator "" s(const char8_t *__str, size_t __len) _NOEXCEPT
4450    {
4451        return basic_string<char8_t> (__str, __len);
4452    }
4453#endif
4454
4455    inline _LIBCPP_INLINE_VISIBILITY
4456    basic_string<char16_t> operator "" s( const char16_t *__str, size_t __len )
4457    {
4458        return basic_string<char16_t> (__str, __len);
4459    }
4460
4461    inline _LIBCPP_INLINE_VISIBILITY
4462    basic_string<char32_t> operator "" s( const char32_t *__str, size_t __len )
4463    {
4464        return basic_string<char32_t> (__str, __len);
4465    }
4466  }
4467}
4468#endif
4469
4470_LIBCPP_END_NAMESPACE_STD
4471
4472_LIBCPP_POP_MACROS
4473
4474#endif  // _LIBCPP_STRING
4475