xref: /llvm-project-15.0.7/libcxx/include/string (revision c83cd8fe)
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>;
72template <> struct char_traits<char8_t>;  // C++20
73template <> struct char_traits<char16_t>;
74template <> struct char_traits<char32_t>;
75
76template<class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
77class basic_string
78{
79public:
80// types:
81    typedef traits traits_type;
82    typedef typename traits_type::char_type value_type;
83    typedef Allocator allocator_type;
84    typedef typename allocator_type::size_type size_type;
85    typedef typename allocator_type::difference_type difference_type;
86    typedef typename allocator_type::reference reference;
87    typedef typename allocator_type::const_reference const_reference;
88    typedef typename allocator_type::pointer pointer;
89    typedef typename allocator_type::const_pointer const_pointer;
90    typedef implementation-defined iterator;
91    typedef implementation-defined const_iterator;
92    typedef std::reverse_iterator<iterator> reverse_iterator;
93    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
94
95    static const size_type npos = -1;
96
97    basic_string()
98        noexcept(is_nothrow_default_constructible<allocator_type>::value);
99    explicit basic_string(const allocator_type& a);
100    basic_string(const basic_string& str);
101    basic_string(basic_string&& str)
102        noexcept(is_nothrow_move_constructible<allocator_type>::value);
103    basic_string(const basic_string& str, size_type pos,
104                 const allocator_type& a = allocator_type());
105    basic_string(const basic_string& str, size_type pos, size_type n,
106                 const Allocator& a = Allocator());
107    template<class T>
108        basic_string(const T& t, size_type pos, size_type n, const Allocator& a = Allocator()); // C++17
109    template <class T>
110        explicit basic_string(const T& t, const Allocator& a = Allocator()); // C++17
111    basic_string(const value_type* s, const allocator_type& a = allocator_type());
112    basic_string(const value_type* s, size_type n, const allocator_type& a = allocator_type());
113    basic_string(size_type n, value_type c, const allocator_type& a = allocator_type());
114    template<class InputIterator>
115        basic_string(InputIterator begin, InputIterator end,
116                     const allocator_type& a = allocator_type());
117    basic_string(initializer_list<value_type>, const Allocator& = Allocator());
118    basic_string(const basic_string&, const Allocator&);
119    basic_string(basic_string&&, const Allocator&);
120
121    ~basic_string();
122
123    operator basic_string_view<charT, traits>() const noexcept;
124
125    basic_string& operator=(const basic_string& str);
126    template <class T>
127        basic_string& operator=(const T& t); // C++17
128    basic_string& operator=(basic_string&& str)
129        noexcept(
130             allocator_type::propagate_on_container_move_assignment::value ||
131             allocator_type::is_always_equal::value ); // C++17
132    basic_string& operator=(const value_type* s);
133    basic_string& operator=(value_type c);
134    basic_string& operator=(initializer_list<value_type>);
135
136    iterator       begin() noexcept;
137    const_iterator begin() const noexcept;
138    iterator       end() noexcept;
139    const_iterator end() const noexcept;
140
141    reverse_iterator       rbegin() noexcept;
142    const_reverse_iterator rbegin() const noexcept;
143    reverse_iterator       rend() noexcept;
144    const_reverse_iterator rend() const noexcept;
145
146    const_iterator         cbegin() const noexcept;
147    const_iterator         cend() const noexcept;
148    const_reverse_iterator crbegin() const noexcept;
149    const_reverse_iterator crend() const noexcept;
150
151    size_type size() const noexcept;
152    size_type length() const noexcept;
153    size_type max_size() const noexcept;
154    size_type capacity() const noexcept;
155
156    void resize(size_type n, value_type c);
157    void resize(size_type n);
158
159    void reserve(size_type res_arg);
160    void reserve(); // deprecated in C++20
161    void shrink_to_fit();
162    void clear() noexcept;
163    bool empty() const noexcept;
164
165    const_reference operator[](size_type pos) const;
166    reference       operator[](size_type pos);
167
168    const_reference at(size_type n) const;
169    reference       at(size_type n);
170
171    basic_string& operator+=(const basic_string& str);
172    template <class T>
173        basic_string& operator+=(const T& t);              // C++17
174    basic_string& operator+=(const value_type* s);
175    basic_string& operator+=(value_type c);
176    basic_string& operator+=(initializer_list<value_type>);
177
178    basic_string& append(const basic_string& str);
179    template <class T>
180        basic_string& append(const T& t);                 // C++17
181    basic_string& append(const basic_string& str, size_type pos, size_type n=npos); //C++14
182    template <class T>
183        basic_string& append(const T& t, size_type pos, size_type n=npos); // C++17
184    basic_string& append(const value_type* s, size_type n);
185    basic_string& append(const value_type* s);
186    basic_string& append(size_type n, value_type c);
187    template<class InputIterator>
188        basic_string& append(InputIterator first, InputIterator last);
189    basic_string& append(initializer_list<value_type>);
190
191    void push_back(value_type c);
192    void pop_back();
193    reference       front();
194    const_reference front() const;
195    reference       back();
196    const_reference back() const;
197
198    basic_string& assign(const basic_string& str);
199    template <class T>
200        basic_string& assign(const T& t);  // C++17
201    basic_string& assign(basic_string&& str);
202    basic_string& assign(const basic_string& str, size_type pos, size_type n=npos); // C++14
203    template <class T>
204        basic_string& assign(const T& t, size_type pos, size_type n=npos); // C++17
205    basic_string& assign(const value_type* s, size_type n);
206    basic_string& assign(const value_type* s);
207    basic_string& assign(size_type n, value_type c);
208    template<class InputIterator>
209        basic_string& assign(InputIterator first, InputIterator last);
210    basic_string& assign(initializer_list<value_type>);
211
212    basic_string& insert(size_type pos1, const basic_string& str);
213    template <class T>
214        basic_string& insert(size_type pos1, const T& t);
215    basic_string& insert(size_type pos1, const basic_string& str,
216                         size_type pos2, size_type n);
217    template <class T>
218        basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n); // C++17
219    basic_string& insert(size_type pos, const value_type* s, size_type n=npos); //C++14
220    basic_string& insert(size_type pos, const value_type* s);
221    basic_string& insert(size_type pos, size_type n, value_type c);
222    iterator      insert(const_iterator p, value_type c);
223    iterator      insert(const_iterator p, size_type n, value_type c);
224    template<class InputIterator>
225        iterator insert(const_iterator p, InputIterator first, InputIterator last);
226    iterator      insert(const_iterator p, initializer_list<value_type>);
227
228    basic_string& erase(size_type pos = 0, size_type n = npos);
229    iterator      erase(const_iterator position);
230    iterator      erase(const_iterator first, const_iterator last);
231
232    basic_string& replace(size_type pos1, size_type n1, const basic_string& str);
233    template <class T>
234    basic_string& replace(size_type pos1, size_type n1, const T& t);  // C++17
235    basic_string& replace(size_type pos1, size_type n1, const basic_string& str,
236                          size_type pos2, size_type n2=npos); // C++14
237    template <class T>
238        basic_string& replace(size_type pos1, size_type n1, const T& t,
239                              size_type pos2, size_type n); // C++17
240    basic_string& replace(size_type pos, size_type n1, const value_type* s, size_type n2);
241    basic_string& replace(size_type pos, size_type n1, const value_type* s);
242    basic_string& replace(size_type pos, size_type n1, size_type n2, value_type c);
243    basic_string& replace(const_iterator i1, const_iterator i2, const basic_string& str);
244    template <class T>
245        basic_string& replace(const_iterator i1, const_iterator i2, const T& t);  // C++17
246    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s, size_type n);
247    basic_string& replace(const_iterator i1, const_iterator i2, const value_type* s);
248    basic_string& replace(const_iterator i1, const_iterator i2, size_type n, value_type c);
249    template<class InputIterator>
250        basic_string& replace(const_iterator i1, const_iterator i2, InputIterator j1, InputIterator j2);
251    basic_string& replace(const_iterator i1, const_iterator i2, initializer_list<value_type>);
252
253    size_type copy(value_type* s, size_type n, size_type pos = 0) const;
254    basic_string substr(size_type pos = 0, size_type n = npos) const;
255
256    void swap(basic_string& str)
257        noexcept(allocator_traits<allocator_type>::propagate_on_container_swap::value ||
258                 allocator_traits<allocator_type>::is_always_equal::value);  // C++17
259
260    const value_type* c_str() const noexcept;
261    const value_type* data() const noexcept;
262          value_type* data()       noexcept;   // C++17
263
264    allocator_type get_allocator() const noexcept;
265
266    size_type find(const basic_string& str, size_type pos = 0) const noexcept;
267    template <class T>
268        size_type find(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
269    size_type find(const value_type* s, size_type pos, size_type n) const noexcept;
270    size_type find(const value_type* s, size_type pos = 0) const noexcept;
271    size_type find(value_type c, size_type pos = 0) const noexcept;
272
273    size_type rfind(const basic_string& str, size_type pos = npos) const noexcept;
274    template <class T>
275        size_type rfind(const T& t, size_type pos = npos) const noexcept; // C++17, noexcept as an extension
276    size_type rfind(const value_type* s, size_type pos, size_type n) const noexcept;
277    size_type rfind(const value_type* s, size_type pos = npos) const noexcept;
278    size_type rfind(value_type c, size_type pos = npos) const noexcept;
279
280    size_type find_first_of(const basic_string& str, size_type pos = 0) const noexcept;
281    template <class T>
282        size_type find_first_of(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
283    size_type find_first_of(const value_type* s, size_type pos, size_type n) const noexcept;
284    size_type find_first_of(const value_type* s, size_type pos = 0) const noexcept;
285    size_type find_first_of(value_type c, size_type pos = 0) const noexcept;
286
287    size_type find_last_of(const basic_string& str, size_type pos = npos) const noexcept;
288    template <class T>
289        size_type find_last_of(const T& t, size_type pos = npos) const noexcept noexcept; // C++17, noexcept as an extension
290    size_type find_last_of(const value_type* s, size_type pos, size_type n) const noexcept;
291    size_type find_last_of(const value_type* s, size_type pos = npos) const noexcept;
292    size_type find_last_of(value_type c, size_type pos = npos) const noexcept;
293
294    size_type find_first_not_of(const basic_string& str, size_type pos = 0) const noexcept;
295    template <class T>
296        size_type find_first_not_of(const T& t, size_type pos = 0) const noexcept; // C++17, noexcept as an extension
297    size_type find_first_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
298    size_type find_first_not_of(const value_type* s, size_type pos = 0) const noexcept;
299    size_type find_first_not_of(value_type c, size_type pos = 0) const noexcept;
300
301    size_type find_last_not_of(const basic_string& str, size_type pos = npos) const noexcept;
302    template <class T>
303        size_type find_last_not_of(const T& t, size_type pos = npos) const noexcept; // C++17, noexcept as an extension
304    size_type find_last_not_of(const value_type* s, size_type pos, size_type n) const noexcept;
305    size_type find_last_not_of(const value_type* s, size_type pos = npos) const noexcept;
306    size_type find_last_not_of(value_type c, size_type pos = npos) const noexcept;
307
308    int compare(const basic_string& str) const noexcept;
309    template <class T>
310        int compare(const T& t) const noexcept;  // C++17, noexcept as an extension
311    int compare(size_type pos1, size_type n1, const basic_string& str) const;
312    template <class T>
313        int compare(size_type pos1, size_type n1, const T& t) const;  // C++17
314    int compare(size_type pos1, size_type n1, const basic_string& str,
315                size_type pos2, size_type n2=npos) const; // C++14
316    template <class T>
317        int compare(size_type pos1, size_type n1, const T& t,
318                    size_type pos2, size_type n2=npos) const; // C++17
319    int compare(const value_type* s) const noexcept;
320    int compare(size_type pos1, size_type n1, const value_type* s) const;
321    int compare(size_type pos1, size_type n1, const value_type* s, size_type n2) const;
322
323    bool starts_with(basic_string_view<charT, traits> sv) const noexcept; // C++20
324    bool starts_with(charT c) const noexcept;                             // C++20
325    bool starts_with(const charT* s) const;                               // C++20
326    bool ends_with(basic_string_view<charT, traits> sv) const noexcept;   // C++20
327    bool ends_with(charT c) const noexcept;                               // C++20
328    bool ends_with(const charT* s) const;                                 // C++20
329
330    constexpr bool contains(basic_string_view<charT, traits> sv) const noexcept; // C++2b
331    constexpr bool contains(charT c) const noexcept;                             // C++2b
332    constexpr bool contains(const charT* s) const;                               // C++2b
333
334    bool __invariants() const;
335};
336
337template<class InputIterator,
338         class Allocator = allocator<typename iterator_traits<InputIterator>::value_type>>
339basic_string(InputIterator, InputIterator, Allocator = Allocator())
340   -> basic_string<typename iterator_traits<InputIterator>::value_type,
341                  char_traits<typename iterator_traits<InputIterator>::value_type>,
342                  Allocator>;   // C++17
343
344template<class charT, class traits, class Allocator>
345basic_string<charT, traits, Allocator>
346operator+(const basic_string<charT, traits, Allocator>& lhs,
347          const basic_string<charT, traits, Allocator>& rhs);
348
349template<class charT, class traits, class Allocator>
350basic_string<charT, traits, Allocator>
351operator+(const charT* lhs , const basic_string<charT,traits,Allocator>&rhs);
352
353template<class charT, class traits, class Allocator>
354basic_string<charT, traits, Allocator>
355operator+(charT lhs, const basic_string<charT,traits,Allocator>& rhs);
356
357template<class charT, class traits, class Allocator>
358basic_string<charT, traits, Allocator>
359operator+(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs);
360
361template<class charT, class traits, class Allocator>
362basic_string<charT, traits, Allocator>
363operator+(const basic_string<charT, traits, Allocator>& lhs, charT rhs);
364
365template<class charT, class traits, class Allocator>
366bool operator==(const basic_string<charT, traits, Allocator>& lhs,
367                const basic_string<charT, traits, Allocator>& rhs) noexcept;
368
369template<class charT, class traits, class Allocator>
370bool operator==(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
371
372template<class charT, class traits, class Allocator>
373bool operator==(const basic_string<charT,traits,Allocator>& lhs, const charT* rhs) noexcept;
374
375template<class charT, class traits, class Allocator>
376bool operator!=(const basic_string<charT,traits,Allocator>& lhs,
377                const basic_string<charT, traits, Allocator>& rhs) noexcept;
378
379template<class charT, class traits, class Allocator>
380bool operator!=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
381
382template<class charT, class traits, class Allocator>
383bool operator!=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
384
385template<class charT, class traits, class Allocator>
386bool operator< (const basic_string<charT, traits, Allocator>& lhs,
387                const basic_string<charT, traits, Allocator>& rhs) noexcept;
388
389template<class charT, class traits, class Allocator>
390bool operator< (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
391
392template<class charT, class traits, class Allocator>
393bool operator< (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
394
395template<class charT, class traits, class Allocator>
396bool operator> (const basic_string<charT, traits, Allocator>& lhs,
397                const basic_string<charT, traits, Allocator>& rhs) noexcept;
398
399template<class charT, class traits, class Allocator>
400bool operator> (const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
401
402template<class charT, class traits, class Allocator>
403bool operator> (const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
404
405template<class charT, class traits, class Allocator>
406bool operator<=(const basic_string<charT, traits, Allocator>& lhs,
407                const basic_string<charT, traits, Allocator>& rhs) noexcept;
408
409template<class charT, class traits, class Allocator>
410bool operator<=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
411
412template<class charT, class traits, class Allocator>
413bool operator<=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
414
415template<class charT, class traits, class Allocator>
416bool operator>=(const basic_string<charT, traits, Allocator>& lhs,
417                const basic_string<charT, traits, Allocator>& rhs) noexcept;
418
419template<class charT, class traits, class Allocator>
420bool operator>=(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs) noexcept;
421
422template<class charT, class traits, class Allocator>
423bool operator>=(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs) noexcept;
424
425template<class charT, class traits, class Allocator>
426void swap(basic_string<charT, traits, Allocator>& lhs,
427          basic_string<charT, traits, Allocator>& rhs)
428            noexcept(noexcept(lhs.swap(rhs)));
429
430template<class charT, class traits, class Allocator>
431basic_istream<charT, traits>&
432operator>>(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);
433
434template<class charT, class traits, class Allocator>
435basic_ostream<charT, traits>&
436operator<<(basic_ostream<charT, traits>& os, const basic_string<charT, traits, Allocator>& str);
437
438template<class charT, class traits, class Allocator>
439basic_istream<charT, traits>&
440getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str,
441        charT delim);
442
443template<class charT, class traits, class Allocator>
444basic_istream<charT, traits>&
445getline(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);
446
447template<class charT, class traits, class Allocator, class U>
448typename basic_string<charT, traits, Allocator>::size_type
449erase(basic_string<charT, traits, Allocator>& c, const U& value);    // C++20
450template<class charT, class traits, class Allocator, class Predicate>
451typename basic_string<charT, traits, Allocator>::size_type
452erase_if(basic_string<charT, traits, Allocator>& c, Predicate pred); // C++20
453
454typedef basic_string<char>    string;
455typedef basic_string<wchar_t> wstring;
456typedef basic_string<char8_t> u8string; // C++20
457typedef basic_string<char16_t> u16string;
458typedef basic_string<char32_t> u32string;
459
460int                stoi  (const string& str, size_t* idx = nullptr, int base = 10);
461long               stol  (const string& str, size_t* idx = nullptr, int base = 10);
462unsigned long      stoul (const string& str, size_t* idx = nullptr, int base = 10);
463long long          stoll (const string& str, size_t* idx = nullptr, int base = 10);
464unsigned long long stoull(const string& str, size_t* idx = nullptr, int base = 10);
465
466float       stof (const string& str, size_t* idx = nullptr);
467double      stod (const string& str, size_t* idx = nullptr);
468long double stold(const string& str, size_t* idx = nullptr);
469
470string to_string(int val);
471string to_string(unsigned val);
472string to_string(long val);
473string to_string(unsigned long val);
474string to_string(long long val);
475string to_string(unsigned long long val);
476string to_string(float val);
477string to_string(double val);
478string to_string(long double val);
479
480int                stoi  (const wstring& str, size_t* idx = nullptr, int base = 10);
481long               stol  (const wstring& str, size_t* idx = nullptr, int base = 10);
482unsigned long      stoul (const wstring& str, size_t* idx = nullptr, int base = 10);
483long long          stoll (const wstring& str, size_t* idx = nullptr, int base = 10);
484unsigned long long stoull(const wstring& str, size_t* idx = nullptr, int base = 10);
485
486float       stof (const wstring& str, size_t* idx = nullptr);
487double      stod (const wstring& str, size_t* idx = nullptr);
488long double stold(const wstring& str, size_t* idx = nullptr);
489
490wstring to_wstring(int val);
491wstring to_wstring(unsigned val);
492wstring to_wstring(long val);
493wstring to_wstring(unsigned long val);
494wstring to_wstring(long long val);
495wstring to_wstring(unsigned long long val);
496wstring to_wstring(float val);
497wstring to_wstring(double val);
498wstring to_wstring(long double val);
499
500template <> struct hash<string>;
501template <> struct hash<u8string>; // C++20
502template <> struct hash<u16string>;
503template <> struct hash<u32string>;
504template <> struct hash<wstring>;
505
506basic_string<char>     operator "" s( const char *str,     size_t len ); // C++14
507basic_string<wchar_t>  operator "" s( const wchar_t *str,  size_t len ); // C++14
508basic_string<char8_t>  operator "" s( const char8_t *str,  size_t len ); // C++20
509basic_string<char16_t> operator "" s( const char16_t *str, size_t len ); // C++14
510basic_string<char32_t> operator "" s( const char32_t *str, size_t len ); // C++14
511
512}  // std
513
514*/
515
516#include <__config>
517#include <string_view>
518#include <iosfwd>
519#include <cstring>
520#include <cstdio>  // For EOF.
521#include <cwchar>
522#include <algorithm>
523#include <iterator>
524#include <utility>
525#include <memory>
526#include <stdexcept>
527#include <type_traits>
528#include <initializer_list>
529#include <__functional_base>
530#include <version>
531#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
532#include <cstdint>
533#endif
534
535#include <__debug>
536
537#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
538#pragma GCC system_header
539#endif
540
541_LIBCPP_PUSH_MACROS
542#include <__undef_macros>
543
544
545_LIBCPP_BEGIN_NAMESPACE_STD
546
547// fpos
548
549template <class _StateT>
550class _LIBCPP_TEMPLATE_VIS fpos
551{
552private:
553    _StateT __st_;
554    streamoff __off_;
555public:
556    _LIBCPP_INLINE_VISIBILITY fpos(streamoff __off = streamoff()) : __st_(), __off_(__off) {}
557
558    _LIBCPP_INLINE_VISIBILITY operator streamoff() const {return __off_;}
559
560    _LIBCPP_INLINE_VISIBILITY _StateT state() const {return __st_;}
561    _LIBCPP_INLINE_VISIBILITY void state(_StateT __st) {__st_ = __st;}
562
563    _LIBCPP_INLINE_VISIBILITY fpos& operator+=(streamoff __off) {__off_ += __off; return *this;}
564    _LIBCPP_INLINE_VISIBILITY fpos  operator+ (streamoff __off) const {fpos __t(*this); __t += __off; return __t;}
565    _LIBCPP_INLINE_VISIBILITY fpos& operator-=(streamoff __off) {__off_ -= __off; return *this;}
566    _LIBCPP_INLINE_VISIBILITY fpos  operator- (streamoff __off) const {fpos __t(*this); __t -= __off; return __t;}
567};
568
569template <class _StateT>
570inline _LIBCPP_INLINE_VISIBILITY
571streamoff operator-(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
572    {return streamoff(__x) - streamoff(__y);}
573
574template <class _StateT>
575inline _LIBCPP_INLINE_VISIBILITY
576bool operator==(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
577    {return streamoff(__x) == streamoff(__y);}
578
579template <class _StateT>
580inline _LIBCPP_INLINE_VISIBILITY
581bool operator!=(const fpos<_StateT>& __x, const fpos<_StateT>& __y)
582    {return streamoff(__x) != streamoff(__y);}
583
584// basic_string
585
586template<class _CharT, class _Traits, class _Allocator>
587basic_string<_CharT, _Traits, _Allocator>
588operator+(const basic_string<_CharT, _Traits, _Allocator>& __x,
589          const basic_string<_CharT, _Traits, _Allocator>& __y);
590
591template<class _CharT, class _Traits, class _Allocator>
592basic_string<_CharT, _Traits, _Allocator>
593operator+(const _CharT* __x, const basic_string<_CharT,_Traits,_Allocator>& __y);
594
595template<class _CharT, class _Traits, class _Allocator>
596basic_string<_CharT, _Traits, _Allocator>
597operator+(_CharT __x, const basic_string<_CharT,_Traits,_Allocator>& __y);
598
599template<class _CharT, class _Traits, class _Allocator>
600inline _LIBCPP_INLINE_VISIBILITY
601basic_string<_CharT, _Traits, _Allocator>
602operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, const _CharT* __y);
603
604template<class _CharT, class _Traits, class _Allocator>
605basic_string<_CharT, _Traits, _Allocator>
606operator+(const basic_string<_CharT, _Traits, _Allocator>& __x, _CharT __y);
607
608_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS string operator+<char, char_traits<char>, allocator<char> >(char const*, string const&))
609
610template <bool>
611class _LIBCPP_TEMPLATE_VIS __basic_string_common
612{
613protected:
614    _LIBCPP_NORETURN void __throw_length_error() const;
615    _LIBCPP_NORETURN void __throw_out_of_range() const;
616};
617
618template <bool __b>
619void
620__basic_string_common<__b>::__throw_length_error() const
621{
622    _VSTD::__throw_length_error("basic_string");
623}
624
625template <bool __b>
626void
627__basic_string_common<__b>::__throw_out_of_range() const
628{
629    _VSTD::__throw_out_of_range("basic_string");
630}
631
632_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS __basic_string_common<true>)
633
634#ifdef _LIBCPP_NO_EXCEPTIONS
635template <class _Iter>
636struct __libcpp_string_gets_noexcept_iterator_impl : public true_type {};
637#elif defined(_LIBCPP_HAS_NO_NOEXCEPT)
638template <class _Iter>
639struct __libcpp_string_gets_noexcept_iterator_impl : public false_type {};
640#else
641template <class _Iter, bool = __is_cpp17_forward_iterator<_Iter>::value>
642struct __libcpp_string_gets_noexcept_iterator_impl : public _LIBCPP_BOOL_CONSTANT((
643    noexcept(++(declval<_Iter&>())) &&
644    is_nothrow_assignable<_Iter&, _Iter>::value &&
645    noexcept(declval<_Iter>() == declval<_Iter>()) &&
646    noexcept(*declval<_Iter>())
647)) {};
648
649template <class _Iter>
650struct __libcpp_string_gets_noexcept_iterator_impl<_Iter, false> : public false_type {};
651#endif
652
653
654template <class _Iter>
655struct __libcpp_string_gets_noexcept_iterator
656    : public _LIBCPP_BOOL_CONSTANT(__libcpp_is_trivial_iterator<_Iter>::value || __libcpp_string_gets_noexcept_iterator_impl<_Iter>::value) {};
657
658template <class _CharT, class _Traits, class _Tp>
659struct __can_be_converted_to_string_view : public _BoolConstant<
660      is_convertible<const _Tp&, basic_string_view<_CharT, _Traits> >::value &&
661     !is_convertible<const _Tp&, const _CharT*>::value
662    > {};
663
664#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
665
666template <class _CharT, size_t = sizeof(_CharT)>
667struct __padding
668{
669    unsigned char __xx[sizeof(_CharT)-1];
670};
671
672template <class _CharT>
673struct __padding<_CharT, 1>
674{
675};
676
677#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
678
679#ifndef _LIBCPP_NO_HAS_CHAR8_T
680typedef basic_string<char8_t> u8string;
681#endif
682
683#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
684typedef basic_string<char16_t> u16string;
685typedef basic_string<char32_t> u32string;
686#endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
687
688template<class _CharT, class _Traits, class _Allocator>
689class
690    _LIBCPP_TEMPLATE_VIS
691#ifndef _LIBCPP_NO_HAS_CHAR8_T
692    _LIBCPP_PREFERRED_NAME(u8string)
693#endif
694#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
695    _LIBCPP_PREFERRED_NAME(u16string)
696    _LIBCPP_PREFERRED_NAME(u32string)
697#endif
698    basic_string
699    : private __basic_string_common<true>
700{
701public:
702    typedef basic_string                                 __self;
703    typedef basic_string_view<_CharT, _Traits>           __self_view;
704    typedef _Traits                                      traits_type;
705    typedef _CharT                                       value_type;
706    typedef _Allocator                                   allocator_type;
707    typedef allocator_traits<allocator_type>             __alloc_traits;
708    typedef typename __alloc_traits::size_type           size_type;
709    typedef typename __alloc_traits::difference_type     difference_type;
710    typedef value_type&                                  reference;
711    typedef const value_type&                            const_reference;
712    typedef typename __alloc_traits::pointer             pointer;
713    typedef typename __alloc_traits::const_pointer       const_pointer;
714
715    static_assert((!is_array<value_type>::value), "Character type of basic_string must not be an array");
716    static_assert(( is_standard_layout<value_type>::value), "Character type of basic_string must be standard-layout");
717    static_assert(( is_trivial<value_type>::value), "Character type of basic_string must be trivial");
718    static_assert(( is_same<_CharT, typename traits_type::char_type>::value),
719                  "traits_type::char_type must be the same type as CharT");
720    static_assert(( is_same<typename allocator_type::value_type, value_type>::value),
721                  "Allocator::value_type must be same type as value_type");
722
723    typedef __wrap_iter<pointer>                         iterator;
724    typedef __wrap_iter<const_pointer>                   const_iterator;
725    typedef _VSTD::reverse_iterator<iterator>             reverse_iterator;
726    typedef _VSTD::reverse_iterator<const_iterator>       const_reverse_iterator;
727
728private:
729
730#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
731
732    struct __long
733    {
734        pointer   __data_;
735        size_type __size_;
736        size_type __cap_;
737    };
738
739#ifdef _LIBCPP_BIG_ENDIAN
740    static const size_type __short_mask = 0x01;
741    static const size_type __long_mask  = 0x1ul;
742#else  // _LIBCPP_BIG_ENDIAN
743    static const size_type __short_mask = 0x80;
744    static const size_type __long_mask  = ~(size_type(~0) >> 1);
745#endif  // _LIBCPP_BIG_ENDIAN
746
747    enum {__min_cap = (sizeof(__long) - 1)/sizeof(value_type) > 2 ?
748                      (sizeof(__long) - 1)/sizeof(value_type) : 2};
749
750    struct __short
751    {
752        value_type __data_[__min_cap];
753        struct
754            : __padding<value_type>
755        {
756            unsigned char __size_;
757        };
758    };
759
760#else
761
762    struct __long
763    {
764        size_type __cap_;
765        size_type __size_;
766        pointer   __data_;
767    };
768
769#ifdef _LIBCPP_BIG_ENDIAN
770    static const size_type __short_mask = 0x80;
771    static const size_type __long_mask  = ~(size_type(~0) >> 1);
772#else  // _LIBCPP_BIG_ENDIAN
773    static const size_type __short_mask = 0x01;
774    static const size_type __long_mask  = 0x1ul;
775#endif  // _LIBCPP_BIG_ENDIAN
776
777    enum {__min_cap = (sizeof(__long) - 1)/sizeof(value_type) > 2 ?
778                      (sizeof(__long) - 1)/sizeof(value_type) : 2};
779
780    struct __short
781    {
782        union
783        {
784            unsigned char __size_;
785            value_type __lx;
786        };
787        value_type __data_[__min_cap];
788    };
789
790#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
791
792    union __ulx{__long __lx; __short __lxx;};
793
794    enum {__n_words = sizeof(__ulx) / sizeof(size_type)};
795
796    struct __raw
797    {
798        size_type __words[__n_words];
799    };
800
801    struct __rep
802    {
803        union
804        {
805            __long  __l;
806            __short __s;
807            __raw   __r;
808        };
809    };
810
811    __compressed_pair<__rep, allocator_type> __r_;
812
813public:
814    _LIBCPP_TEMPLATE_DATA_VIS
815    static const size_type npos = -1;
816
817    _LIBCPP_INLINE_VISIBILITY basic_string()
818        _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value);
819
820    _LIBCPP_INLINE_VISIBILITY explicit basic_string(const allocator_type& __a)
821#if _LIBCPP_STD_VER <= 14
822        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value);
823#else
824        _NOEXCEPT;
825#endif
826
827    basic_string(const basic_string& __str);
828    basic_string(const basic_string& __str, const allocator_type& __a);
829
830#ifndef _LIBCPP_CXX03_LANG
831    _LIBCPP_INLINE_VISIBILITY
832    basic_string(basic_string&& __str)
833#if _LIBCPP_STD_VER <= 14
834        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value);
835#else
836        _NOEXCEPT;
837#endif
838
839    _LIBCPP_INLINE_VISIBILITY
840    basic_string(basic_string&& __str, const allocator_type& __a);
841#endif  // _LIBCPP_CXX03_LANG
842
843    template <class = _EnableIf<__is_allocator<_Allocator>::value, nullptr_t> >
844    _LIBCPP_INLINE_VISIBILITY
845    basic_string(const _CharT* __s) : __r_(__default_init_tag(), __default_init_tag()) {
846      _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*) detected nullptr");
847      __init(__s, traits_type::length(__s));
848#   if _LIBCPP_DEBUG_LEVEL == 2
849      __get_db()->__insert_c(this);
850#   endif
851    }
852
853    template <class = _EnableIf<__is_allocator<_Allocator>::value, nullptr_t> >
854        _LIBCPP_INLINE_VISIBILITY
855        basic_string(const _CharT* __s, const _Allocator& __a);
856
857    _LIBCPP_INLINE_VISIBILITY
858    basic_string(const _CharT* __s, size_type __n);
859    _LIBCPP_INLINE_VISIBILITY
860    basic_string(const _CharT* __s, size_type __n, const _Allocator& __a);
861    _LIBCPP_INLINE_VISIBILITY
862    basic_string(size_type __n, _CharT __c);
863
864    template <class = _EnableIf<__is_allocator<_Allocator>::value, nullptr_t> >
865        _LIBCPP_INLINE_VISIBILITY
866        basic_string(size_type __n, _CharT __c, const _Allocator& __a);
867
868    basic_string(const basic_string& __str, size_type __pos, size_type __n,
869                 const _Allocator& __a = _Allocator());
870    _LIBCPP_INLINE_VISIBILITY
871    basic_string(const basic_string& __str, size_type __pos,
872                 const _Allocator& __a = _Allocator());
873
874    template<class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
875        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
876        basic_string(const _Tp& __t, size_type __pos, size_type __n,
877                     const allocator_type& __a = allocator_type());
878
879    template<class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value &&
880                                          !__is_same_uncvref<_Tp, basic_string>::value> >
881        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
882        explicit basic_string(const _Tp& __t);
883
884    template<class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
885        _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
886        explicit basic_string(const _Tp& __t, const allocator_type& __a);
887
888    template<class _InputIterator, class = _EnableIf<__is_cpp17_input_iterator<_InputIterator>::value> >
889        _LIBCPP_INLINE_VISIBILITY
890        basic_string(_InputIterator __first, _InputIterator __last);
891    template<class _InputIterator, class = _EnableIf<__is_cpp17_input_iterator<_InputIterator>::value> >
892        _LIBCPP_INLINE_VISIBILITY
893        basic_string(_InputIterator __first, _InputIterator __last, const allocator_type& __a);
894#ifndef _LIBCPP_CXX03_LANG
895    _LIBCPP_INLINE_VISIBILITY
896    basic_string(initializer_list<_CharT> __il);
897    _LIBCPP_INLINE_VISIBILITY
898    basic_string(initializer_list<_CharT> __il, const _Allocator& __a);
899#endif  // _LIBCPP_CXX03_LANG
900
901    inline ~basic_string();
902
903    _LIBCPP_INLINE_VISIBILITY
904    operator __self_view() const _NOEXCEPT { return __self_view(data(), size()); }
905
906    basic_string& operator=(const basic_string& __str);
907
908    template <class _Tp, class = _EnableIf<__can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value> >
909    basic_string& operator=(const _Tp& __t)
910        {__self_view __sv = __t; return assign(__sv);}
911
912#ifndef _LIBCPP_CXX03_LANG
913    _LIBCPP_INLINE_VISIBILITY
914    basic_string& operator=(basic_string&& __str)
915        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value));
916     _LIBCPP_INLINE_VISIBILITY
917    basic_string& operator=(initializer_list<value_type> __il) {return assign(__il.begin(), __il.size());}
918#endif
919    _LIBCPP_INLINE_VISIBILITY basic_string& operator=(const value_type* __s) {return assign(__s);}
920    basic_string& operator=(value_type __c);
921
922#if _LIBCPP_DEBUG_LEVEL == 2
923    _LIBCPP_INLINE_VISIBILITY
924    iterator begin() _NOEXCEPT
925        {return iterator(this, __get_pointer());}
926    _LIBCPP_INLINE_VISIBILITY
927    const_iterator begin() const _NOEXCEPT
928        {return const_iterator(this, __get_pointer());}
929    _LIBCPP_INLINE_VISIBILITY
930    iterator end() _NOEXCEPT
931        {return iterator(this, __get_pointer() + size());}
932    _LIBCPP_INLINE_VISIBILITY
933    const_iterator end() const _NOEXCEPT
934        {return const_iterator(this, __get_pointer() + size());}
935#else
936    _LIBCPP_INLINE_VISIBILITY
937    iterator begin() _NOEXCEPT
938        {return iterator(__get_pointer());}
939    _LIBCPP_INLINE_VISIBILITY
940    const_iterator begin() const _NOEXCEPT
941        {return const_iterator(__get_pointer());}
942    _LIBCPP_INLINE_VISIBILITY
943    iterator end() _NOEXCEPT
944        {return iterator(__get_pointer() + size());}
945    _LIBCPP_INLINE_VISIBILITY
946    const_iterator end() const _NOEXCEPT
947        {return const_iterator(__get_pointer() + size());}
948#endif  // _LIBCPP_DEBUG_LEVEL == 2
949    _LIBCPP_INLINE_VISIBILITY
950    reverse_iterator rbegin() _NOEXCEPT
951        {return reverse_iterator(end());}
952    _LIBCPP_INLINE_VISIBILITY
953    const_reverse_iterator rbegin() const _NOEXCEPT
954        {return const_reverse_iterator(end());}
955    _LIBCPP_INLINE_VISIBILITY
956    reverse_iterator rend() _NOEXCEPT
957        {return reverse_iterator(begin());}
958    _LIBCPP_INLINE_VISIBILITY
959    const_reverse_iterator rend() const _NOEXCEPT
960        {return const_reverse_iterator(begin());}
961
962    _LIBCPP_INLINE_VISIBILITY
963    const_iterator cbegin() const _NOEXCEPT
964        {return begin();}
965    _LIBCPP_INLINE_VISIBILITY
966    const_iterator cend() const _NOEXCEPT
967        {return end();}
968    _LIBCPP_INLINE_VISIBILITY
969    const_reverse_iterator crbegin() const _NOEXCEPT
970        {return rbegin();}
971    _LIBCPP_INLINE_VISIBILITY
972    const_reverse_iterator crend() const _NOEXCEPT
973        {return rend();}
974
975    _LIBCPP_INLINE_VISIBILITY size_type size() const _NOEXCEPT
976        {return __is_long() ? __get_long_size() : __get_short_size();}
977    _LIBCPP_INLINE_VISIBILITY size_type length() const _NOEXCEPT {return size();}
978    _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT;
979    _LIBCPP_INLINE_VISIBILITY size_type capacity() const _NOEXCEPT
980        {return (__is_long() ? __get_long_cap()
981                             : static_cast<size_type>(__min_cap)) - 1;}
982
983    void resize(size_type __n, value_type __c);
984    _LIBCPP_INLINE_VISIBILITY void resize(size_type __n) {resize(__n, value_type());}
985
986    void reserve(size_type __requested_capacity);
987    _LIBCPP_INLINE_VISIBILITY void __resize_default_init(size_type __n);
988
989    _LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_INLINE_VISIBILITY
990    void reserve() _NOEXCEPT {shrink_to_fit();}
991    _LIBCPP_INLINE_VISIBILITY
992    void shrink_to_fit() _NOEXCEPT;
993    _LIBCPP_INLINE_VISIBILITY
994    void clear() _NOEXCEPT;
995    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
996    bool empty() const _NOEXCEPT {return size() == 0;}
997
998    _LIBCPP_INLINE_VISIBILITY const_reference operator[](size_type __pos) const _NOEXCEPT;
999    _LIBCPP_INLINE_VISIBILITY reference       operator[](size_type __pos)       _NOEXCEPT;
1000
1001    const_reference at(size_type __n) const;
1002    reference       at(size_type __n);
1003
1004    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const basic_string& __str) {return append(__str);}
1005
1006    template <class _Tp>
1007    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1008    _EnableIf
1009        <
1010            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1011            && !__is_same_uncvref<_Tp, basic_string >::value,
1012            basic_string&
1013        >
1014                                            operator+=(const _Tp& __t)            {__self_view __sv = __t; return append(__sv);}
1015    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(const value_type* __s)     {return append(__s);}
1016    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(value_type __c)            {push_back(__c); return *this;}
1017#ifndef _LIBCPP_CXX03_LANG
1018    _LIBCPP_INLINE_VISIBILITY basic_string& operator+=(initializer_list<value_type> __il) {return append(__il);}
1019#endif  // _LIBCPP_CXX03_LANG
1020
1021    _LIBCPP_INLINE_VISIBILITY
1022    basic_string& append(const basic_string& __str);
1023
1024    template <class _Tp>
1025    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1026    _EnableIf<
1027            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1028            && !__is_same_uncvref<_Tp, basic_string>::value,
1029            basic_string&
1030        >
1031                  append(const _Tp& __t) { __self_view __sv = __t; return append(__sv.data(), __sv.size()); }
1032    basic_string& append(const basic_string& __str, size_type __pos, size_type __n=npos);
1033
1034    template <class _Tp>
1035    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1036    _EnableIf
1037        <
1038            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1039            && !__is_same_uncvref<_Tp, basic_string>::value,
1040            basic_string&
1041        >
1042                  append(const _Tp& __t, size_type __pos, size_type __n=npos);
1043    basic_string& append(const value_type* __s, size_type __n);
1044    basic_string& append(const value_type* __s);
1045    basic_string& append(size_type __n, value_type __c);
1046
1047    _LIBCPP_INLINE_VISIBILITY
1048    void __append_default_init(size_type __n);
1049
1050    template <class _ForwardIterator>
1051    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1052    basic_string& __append_forward_unsafe(_ForwardIterator, _ForwardIterator);
1053    template<class _InputIterator>
1054    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1055    _EnableIf
1056        <
1057            __is_exactly_cpp17_input_iterator<_InputIterator>::value
1058                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
1059            basic_string&
1060        >
1061    _LIBCPP_INLINE_VISIBILITY
1062    append(_InputIterator __first, _InputIterator __last) {
1063      const basic_string __temp (__first, __last, __alloc());
1064      append(__temp.data(), __temp.size());
1065      return *this;
1066    }
1067    template<class _ForwardIterator>
1068    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1069    _EnableIf
1070        <
1071            __is_cpp17_forward_iterator<_ForwardIterator>::value
1072                && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
1073            basic_string&
1074        >
1075    _LIBCPP_INLINE_VISIBILITY
1076    append(_ForwardIterator __first, _ForwardIterator __last) {
1077      return __append_forward_unsafe(__first, __last);
1078    }
1079
1080#ifndef _LIBCPP_CXX03_LANG
1081    _LIBCPP_INLINE_VISIBILITY
1082    basic_string& append(initializer_list<value_type> __il) {return append(__il.begin(), __il.size());}
1083#endif  // _LIBCPP_CXX03_LANG
1084
1085    void push_back(value_type __c);
1086    _LIBCPP_INLINE_VISIBILITY
1087    void pop_back();
1088    _LIBCPP_INLINE_VISIBILITY reference       front() _NOEXCEPT;
1089    _LIBCPP_INLINE_VISIBILITY const_reference front() const _NOEXCEPT;
1090    _LIBCPP_INLINE_VISIBILITY reference       back() _NOEXCEPT;
1091    _LIBCPP_INLINE_VISIBILITY const_reference back() const _NOEXCEPT;
1092
1093    template <class _Tp>
1094    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1095    _EnableIf
1096        <
1097            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1098            basic_string&
1099        >
1100                 assign(const _Tp & __t) { __self_view __sv = __t; return assign(__sv.data(), __sv.size()); }
1101    _LIBCPP_INLINE_VISIBILITY
1102    basic_string& assign(const basic_string& __str) { return *this = __str; }
1103#ifndef _LIBCPP_CXX03_LANG
1104    _LIBCPP_INLINE_VISIBILITY
1105    basic_string& assign(basic_string&& __str)
1106        _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
1107        {*this = _VSTD::move(__str); return *this;}
1108#endif
1109    basic_string& assign(const basic_string& __str, size_type __pos, size_type __n=npos);
1110    template <class _Tp>
1111    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1112    _EnableIf
1113        <
1114            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
1115            && !__is_same_uncvref<_Tp, basic_string>::value,
1116            basic_string&
1117        >
1118                  assign(const _Tp & __t, size_type __pos, size_type __n=npos);
1119    basic_string& assign(const value_type* __s, size_type __n);
1120    basic_string& assign(const value_type* __s);
1121    basic_string& assign(size_type __n, value_type __c);
1122    template<class _InputIterator>
1123    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1124    _EnableIf
1125        <
1126           __is_exactly_cpp17_input_iterator<_InputIterator>::value
1127                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
1128            basic_string&
1129        >
1130        assign(_InputIterator __first, _InputIterator __last);
1131    template<class _ForwardIterator>
1132    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1133    _EnableIf
1134        <
1135            __is_cpp17_forward_iterator<_ForwardIterator>::value
1136                 && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
1137            basic_string&
1138        >
1139        assign(_ForwardIterator __first, _ForwardIterator __last);
1140#ifndef _LIBCPP_CXX03_LANG
1141    _LIBCPP_INLINE_VISIBILITY
1142    basic_string& assign(initializer_list<value_type> __il) {return assign(__il.begin(), __il.size());}
1143#endif  // _LIBCPP_CXX03_LANG
1144
1145    _LIBCPP_INLINE_VISIBILITY
1146    basic_string& insert(size_type __pos1, const basic_string& __str);
1147
1148    template <class _Tp>
1149    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1150    _EnableIf
1151        <
1152            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1153            basic_string&
1154        >
1155                 insert(size_type __pos1, const _Tp& __t)
1156    { __self_view __sv = __t; return insert(__pos1, __sv.data(), __sv.size()); }
1157
1158    template <class _Tp>
1159    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1160    _EnableIf
1161        <
1162            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string>::value,
1163            basic_string&
1164        >
1165                  insert(size_type __pos1, const _Tp& __t, size_type __pos2, size_type __n=npos);
1166    basic_string& insert(size_type __pos1, const basic_string& __str, size_type __pos2, size_type __n=npos);
1167    basic_string& insert(size_type __pos, const value_type* __s, size_type __n);
1168    basic_string& insert(size_type __pos, const value_type* __s);
1169    basic_string& insert(size_type __pos, size_type __n, value_type __c);
1170    iterator      insert(const_iterator __pos, value_type __c);
1171    _LIBCPP_INLINE_VISIBILITY
1172    iterator      insert(const_iterator __pos, size_type __n, value_type __c);
1173    template<class _InputIterator>
1174    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1175    _EnableIf
1176        <
1177           __is_exactly_cpp17_input_iterator<_InputIterator>::value
1178                || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
1179            iterator
1180        >
1181        insert(const_iterator __pos, _InputIterator __first, _InputIterator __last);
1182    template<class _ForwardIterator>
1183    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1184    _EnableIf
1185        <
1186            __is_cpp17_forward_iterator<_ForwardIterator>::value
1187                 && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
1188            iterator
1189        >
1190        insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last);
1191#ifndef _LIBCPP_CXX03_LANG
1192    _LIBCPP_INLINE_VISIBILITY
1193    iterator insert(const_iterator __pos, initializer_list<value_type> __il)
1194                    {return insert(__pos, __il.begin(), __il.end());}
1195#endif  // _LIBCPP_CXX03_LANG
1196
1197    basic_string& erase(size_type __pos = 0, size_type __n = npos);
1198    _LIBCPP_INLINE_VISIBILITY
1199    iterator      erase(const_iterator __pos);
1200    _LIBCPP_INLINE_VISIBILITY
1201    iterator      erase(const_iterator __first, const_iterator __last);
1202
1203    _LIBCPP_INLINE_VISIBILITY
1204    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str);
1205
1206    template <class _Tp>
1207    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1208    _EnableIf
1209        <
1210            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1211            basic_string&
1212        >
1213                  replace(size_type __pos1, size_type __n1, const _Tp& __t) { __self_view __sv = __t; return replace(__pos1, __n1, __sv.data(), __sv.size()); }
1214    basic_string& replace(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos);
1215    template <class _Tp>
1216    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1217    _EnableIf
1218        <
1219            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
1220            basic_string&
1221        >
1222                  replace(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos);
1223    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2);
1224    basic_string& replace(size_type __pos, size_type __n1, const value_type* __s);
1225    basic_string& replace(size_type __pos, size_type __n1, size_type __n2, value_type __c);
1226    _LIBCPP_INLINE_VISIBILITY
1227    basic_string& replace(const_iterator __i1, const_iterator __i2, const basic_string& __str);
1228
1229    template <class _Tp>
1230    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1231    _EnableIf
1232        <
1233            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1234            basic_string&
1235        >
1236                  replace(const_iterator __i1, const_iterator __i2, const _Tp& __t) { __self_view __sv = __t; return replace(__i1 - begin(), __i2 - __i1, __sv); }
1237
1238    _LIBCPP_INLINE_VISIBILITY
1239    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n);
1240    _LIBCPP_INLINE_VISIBILITY
1241    basic_string& replace(const_iterator __i1, const_iterator __i2, const value_type* __s);
1242    _LIBCPP_INLINE_VISIBILITY
1243    basic_string& replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c);
1244    template<class _InputIterator>
1245    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1246    _EnableIf
1247        <
1248            __is_cpp17_input_iterator<_InputIterator>::value,
1249            basic_string&
1250        >
1251        replace(const_iterator __i1, const_iterator __i2, _InputIterator __j1, _InputIterator __j2);
1252#ifndef _LIBCPP_CXX03_LANG
1253    _LIBCPP_INLINE_VISIBILITY
1254    basic_string& replace(const_iterator __i1, const_iterator __i2, initializer_list<value_type> __il)
1255        {return replace(__i1, __i2, __il.begin(), __il.end());}
1256#endif  // _LIBCPP_CXX03_LANG
1257
1258    size_type copy(value_type* __s, size_type __n, size_type __pos = 0) const;
1259    _LIBCPP_INLINE_VISIBILITY
1260    basic_string substr(size_type __pos = 0, size_type __n = npos) const;
1261
1262    _LIBCPP_INLINE_VISIBILITY
1263    void swap(basic_string& __str)
1264#if _LIBCPP_STD_VER >= 14
1265        _NOEXCEPT;
1266#else
1267        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
1268                    __is_nothrow_swappable<allocator_type>::value);
1269#endif
1270
1271    _LIBCPP_INLINE_VISIBILITY
1272    const value_type* c_str() const _NOEXCEPT {return data();}
1273    _LIBCPP_INLINE_VISIBILITY
1274    const value_type* data() const _NOEXCEPT  {return _VSTD::__to_address(__get_pointer());}
1275#if _LIBCPP_STD_VER > 14 || defined(_LIBCPP_BUILDING_LIBRARY)
1276    _LIBCPP_INLINE_VISIBILITY
1277    value_type* data()             _NOEXCEPT  {return _VSTD::__to_address(__get_pointer());}
1278#endif
1279
1280    _LIBCPP_INLINE_VISIBILITY
1281    allocator_type get_allocator() const _NOEXCEPT {return __alloc();}
1282
1283    _LIBCPP_INLINE_VISIBILITY
1284    size_type find(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1285
1286    template <class _Tp>
1287    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1288    _EnableIf
1289        <
1290            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1291            size_type
1292        >
1293              find(const _Tp& __t, size_type __pos = 0) const _NOEXCEPT;
1294    size_type find(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1295    _LIBCPP_INLINE_VISIBILITY
1296    size_type find(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1297    size_type find(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1298
1299    _LIBCPP_INLINE_VISIBILITY
1300    size_type rfind(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1301
1302    template <class _Tp>
1303    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1304    _EnableIf
1305        <
1306            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1307            size_type
1308        >
1309              rfind(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1310    size_type rfind(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1311    _LIBCPP_INLINE_VISIBILITY
1312    size_type rfind(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1313    size_type rfind(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1314
1315    _LIBCPP_INLINE_VISIBILITY
1316    size_type find_first_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1317
1318    template <class _Tp>
1319    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1320    _EnableIf
1321        <
1322            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1323            size_type
1324        >
1325              find_first_of(const _Tp& __t, size_type __pos = 0) const _NOEXCEPT;
1326    size_type find_first_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1327    _LIBCPP_INLINE_VISIBILITY
1328    size_type find_first_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1329    _LIBCPP_INLINE_VISIBILITY
1330    size_type find_first_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1331
1332    _LIBCPP_INLINE_VISIBILITY
1333    size_type find_last_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
1334
1335    template <class _Tp>
1336    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1337    _EnableIf
1338        <
1339            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1340            size_type
1341        >
1342              find_last_of(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1343    size_type find_last_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1344    _LIBCPP_INLINE_VISIBILITY
1345    size_type find_last_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1346    _LIBCPP_INLINE_VISIBILITY
1347    size_type find_last_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1348
1349    _LIBCPP_INLINE_VISIBILITY
1350    size_type find_first_not_of(const basic_string& __str, size_type __pos = 0) const _NOEXCEPT;
1351
1352    template <class _Tp>
1353    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1354    _EnableIf
1355        <
1356            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1357            size_type
1358        >
1359              find_first_not_of(const _Tp &__t, size_type __pos = 0) const _NOEXCEPT;
1360    size_type find_first_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1361    _LIBCPP_INLINE_VISIBILITY
1362    size_type find_first_not_of(const value_type* __s, size_type __pos = 0) const _NOEXCEPT;
1363    _LIBCPP_INLINE_VISIBILITY
1364    size_type find_first_not_of(value_type __c, size_type __pos = 0) const _NOEXCEPT;
1365
1366    _LIBCPP_INLINE_VISIBILITY
1367    size_type find_last_not_of(const basic_string& __str, size_type __pos = npos) const _NOEXCEPT;
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            size_type
1375        >
1376              find_last_not_of(const _Tp& __t, size_type __pos = npos) const _NOEXCEPT;
1377    size_type find_last_not_of(const value_type* __s, size_type __pos, size_type __n) const _NOEXCEPT;
1378    _LIBCPP_INLINE_VISIBILITY
1379    size_type find_last_not_of(const value_type* __s, size_type __pos = npos) const _NOEXCEPT;
1380    _LIBCPP_INLINE_VISIBILITY
1381    size_type find_last_not_of(value_type __c, size_type __pos = npos) const _NOEXCEPT;
1382
1383    _LIBCPP_INLINE_VISIBILITY
1384    int compare(const basic_string& __str) const _NOEXCEPT;
1385
1386    template <class _Tp>
1387    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1388    _EnableIf
1389        <
1390            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1391            int
1392        >
1393        compare(const _Tp &__t) const _NOEXCEPT;
1394
1395    template <class _Tp>
1396    _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS
1397    _EnableIf
1398        <
1399            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
1400            int
1401        >
1402         compare(size_type __pos1, size_type __n1, const _Tp& __t) const;
1403
1404    _LIBCPP_INLINE_VISIBILITY
1405    int compare(size_type __pos1, size_type __n1, const basic_string& __str) const;
1406    int compare(size_type __pos1, size_type __n1, const basic_string& __str, size_type __pos2, size_type __n2=npos) const;
1407
1408    template <class _Tp>
1409    inline _LIBCPP_INLINE_VISIBILITY
1410        _EnableIf
1411        <
1412            __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string>::value,
1413            int
1414        >
1415        compare(size_type __pos1, size_type __n1, const _Tp& __t, size_type __pos2, size_type __n2=npos) const;
1416    int compare(const value_type* __s) const _NOEXCEPT;
1417    int compare(size_type __pos1, size_type __n1, const value_type* __s) const;
1418    int compare(size_type __pos1, size_type __n1, const value_type* __s, size_type __n2) const;
1419
1420#if _LIBCPP_STD_VER > 17
1421    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1422    bool starts_with(__self_view __sv) const _NOEXCEPT
1423    { return __self_view(data(), size()).starts_with(__sv); }
1424
1425    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1426    bool starts_with(value_type __c) const _NOEXCEPT
1427    { return !empty() && _Traits::eq(front(), __c); }
1428
1429    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1430    bool starts_with(const value_type* __s) const _NOEXCEPT
1431    { return starts_with(__self_view(__s)); }
1432
1433    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1434    bool ends_with(__self_view __sv) const _NOEXCEPT
1435    { return __self_view(data(), size()).ends_with( __sv); }
1436
1437    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1438    bool ends_with(value_type __c) const _NOEXCEPT
1439    { return !empty() && _Traits::eq(back(), __c); }
1440
1441    _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1442    bool ends_with(const value_type* __s) const _NOEXCEPT
1443    { return ends_with(__self_view(__s)); }
1444#endif
1445
1446#if _LIBCPP_STD_VER > 20
1447    constexpr _LIBCPP_INLINE_VISIBILITY
1448    bool contains(__self_view __sv) const noexcept
1449    { return __self_view(data(), size()).contains(__sv); }
1450
1451    constexpr _LIBCPP_INLINE_VISIBILITY
1452    bool contains(value_type __c) const noexcept
1453    { return __self_view(data(), size()).contains(__c); }
1454
1455    constexpr _LIBCPP_INLINE_VISIBILITY
1456    bool contains(const value_type* __s) const
1457    { return __self_view(data(), size()).contains(__s); }
1458#endif
1459
1460    _LIBCPP_INLINE_VISIBILITY bool __invariants() const;
1461
1462    _LIBCPP_INLINE_VISIBILITY void __clear_and_shrink() _NOEXCEPT;
1463
1464    _LIBCPP_INLINE_VISIBILITY void __shrink_or_extend(size_type __target_capacity);
1465
1466    _LIBCPP_INLINE_VISIBILITY
1467    bool __is_long() const _NOEXCEPT
1468        {return bool(__r_.first().__s.__size_ & __short_mask);}
1469
1470#if _LIBCPP_DEBUG_LEVEL == 2
1471
1472    bool __dereferenceable(const const_iterator* __i) const;
1473    bool __decrementable(const const_iterator* __i) const;
1474    bool __addable(const const_iterator* __i, ptrdiff_t __n) const;
1475    bool __subscriptable(const const_iterator* __i, ptrdiff_t __n) const;
1476
1477#endif  // _LIBCPP_DEBUG_LEVEL == 2
1478
1479private:
1480    _LIBCPP_INLINE_VISIBILITY
1481    allocator_type& __alloc() _NOEXCEPT
1482        {return __r_.second();}
1483    _LIBCPP_INLINE_VISIBILITY
1484    const allocator_type& __alloc() const _NOEXCEPT
1485        {return __r_.second();}
1486
1487#ifdef _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1488
1489    _LIBCPP_INLINE_VISIBILITY
1490    void __set_short_size(size_type __s) _NOEXCEPT
1491#   ifdef _LIBCPP_BIG_ENDIAN
1492        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
1493#   else
1494        {__r_.first().__s.__size_ = (unsigned char)(__s);}
1495#   endif
1496
1497    _LIBCPP_INLINE_VISIBILITY
1498    size_type __get_short_size() const _NOEXCEPT
1499#   ifdef _LIBCPP_BIG_ENDIAN
1500        {return __r_.first().__s.__size_ >> 1;}
1501#   else
1502        {return __r_.first().__s.__size_;}
1503#   endif
1504
1505#else  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1506
1507    _LIBCPP_INLINE_VISIBILITY
1508    void __set_short_size(size_type __s) _NOEXCEPT
1509#   ifdef _LIBCPP_BIG_ENDIAN
1510        {__r_.first().__s.__size_ = (unsigned char)(__s);}
1511#   else
1512        {__r_.first().__s.__size_ = (unsigned char)(__s << 1);}
1513#   endif
1514
1515    _LIBCPP_INLINE_VISIBILITY
1516    size_type __get_short_size() const _NOEXCEPT
1517#   ifdef _LIBCPP_BIG_ENDIAN
1518        {return __r_.first().__s.__size_;}
1519#   else
1520        {return __r_.first().__s.__size_ >> 1;}
1521#   endif
1522
1523#endif  // _LIBCPP_ABI_ALTERNATE_STRING_LAYOUT
1524
1525    _LIBCPP_INLINE_VISIBILITY
1526    void __set_long_size(size_type __s) _NOEXCEPT
1527        {__r_.first().__l.__size_ = __s;}
1528    _LIBCPP_INLINE_VISIBILITY
1529    size_type __get_long_size() const _NOEXCEPT
1530        {return __r_.first().__l.__size_;}
1531    _LIBCPP_INLINE_VISIBILITY
1532    void __set_size(size_type __s) _NOEXCEPT
1533        {if (__is_long()) __set_long_size(__s); else __set_short_size(__s);}
1534
1535    _LIBCPP_INLINE_VISIBILITY
1536    void __set_long_cap(size_type __s) _NOEXCEPT
1537        {__r_.first().__l.__cap_  = __long_mask | __s;}
1538    _LIBCPP_INLINE_VISIBILITY
1539    size_type __get_long_cap() const _NOEXCEPT
1540        {return __r_.first().__l.__cap_ & size_type(~__long_mask);}
1541
1542    _LIBCPP_INLINE_VISIBILITY
1543    void __set_long_pointer(pointer __p) _NOEXCEPT
1544        {__r_.first().__l.__data_ = __p;}
1545    _LIBCPP_INLINE_VISIBILITY
1546    pointer __get_long_pointer() _NOEXCEPT
1547        {return __r_.first().__l.__data_;}
1548    _LIBCPP_INLINE_VISIBILITY
1549    const_pointer __get_long_pointer() const _NOEXCEPT
1550        {return __r_.first().__l.__data_;}
1551    _LIBCPP_INLINE_VISIBILITY
1552    pointer __get_short_pointer() _NOEXCEPT
1553        {return pointer_traits<pointer>::pointer_to(__r_.first().__s.__data_[0]);}
1554    _LIBCPP_INLINE_VISIBILITY
1555    const_pointer __get_short_pointer() const _NOEXCEPT
1556        {return pointer_traits<const_pointer>::pointer_to(__r_.first().__s.__data_[0]);}
1557    _LIBCPP_INLINE_VISIBILITY
1558    pointer __get_pointer() _NOEXCEPT
1559        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
1560    _LIBCPP_INLINE_VISIBILITY
1561    const_pointer __get_pointer() const _NOEXCEPT
1562        {return __is_long() ? __get_long_pointer() : __get_short_pointer();}
1563
1564    _LIBCPP_INLINE_VISIBILITY
1565    void __zero() _NOEXCEPT
1566        {
1567            size_type (&__a)[__n_words] = __r_.first().__r.__words;
1568            for (unsigned __i = 0; __i < __n_words; ++__i)
1569                __a[__i] = 0;
1570        }
1571
1572    template <size_type __a> static
1573        _LIBCPP_INLINE_VISIBILITY
1574        size_type __align_it(size_type __s) _NOEXCEPT
1575            {return (__s + (__a-1)) & ~(__a-1);}
1576    enum {__alignment = 16};
1577    static _LIBCPP_INLINE_VISIBILITY
1578    size_type __recommend(size_type __s) _NOEXCEPT
1579        {
1580        if (__s < __min_cap) return static_cast<size_type>(__min_cap) - 1;
1581        size_type __guess = __align_it<sizeof(value_type) < __alignment ?
1582                     __alignment/sizeof(value_type) : 1 > (__s+1) - 1;
1583        if (__guess == __min_cap) ++__guess;
1584        return __guess;
1585        }
1586
1587    inline
1588    void __init(const value_type* __s, size_type __sz, size_type __reserve);
1589    inline
1590    void __init(const value_type* __s, size_type __sz);
1591    inline
1592    void __init(size_type __n, value_type __c);
1593
1594    // Slow path for the (inlined) copy constructor for 'long' strings.
1595    // Always externally instantiated and not inlined.
1596    // Requires that __s is zero terminated.
1597    // The main reason for this function to exist is because for unstable, we
1598    // want to allow inlining of the copy constructor. However, we don't want
1599    // to call the __init() functions as those are marked as inline which may
1600    // result in over-aggressive inlining by the compiler, where our aim is
1601    // to only inline the fast path code directly in the ctor.
1602    void __init_copy_ctor_external(const value_type* __s, size_type __sz);
1603
1604    template <class _InputIterator>
1605    inline
1606    _EnableIf
1607    <
1608        __is_exactly_cpp17_input_iterator<_InputIterator>::value
1609    >
1610    __init(_InputIterator __first, _InputIterator __last);
1611
1612    template <class _ForwardIterator>
1613    inline
1614    _EnableIf
1615    <
1616        __is_cpp17_forward_iterator<_ForwardIterator>::value
1617    >
1618    __init(_ForwardIterator __first, _ForwardIterator __last);
1619
1620    void __grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1621                   size_type __n_copy,  size_type __n_del,     size_type __n_add = 0);
1622    void __grow_by_and_replace(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
1623                               size_type __n_copy,  size_type __n_del,
1624                               size_type __n_add, const value_type* __p_new_stuff);
1625
1626    // __assign_no_alias is invoked for assignment operations where we
1627    // have proof that the input does not alias the current instance.
1628    // For example, operator=(basic_string) performs a 'self' check.
1629    template <bool __is_short>
1630    basic_string& __assign_no_alias(const value_type* __s, size_type __n);
1631
1632    _LIBCPP_INLINE_VISIBILITY
1633    void __erase_to_end(size_type __pos);
1634
1635    // __erase_external_with_move is invoked for erase() invocations where
1636    // `n ~= npos`, likely requiring memory moves on the string data.
1637    void __erase_external_with_move(size_type __pos, size_type __n);
1638
1639    _LIBCPP_INLINE_VISIBILITY
1640    void __copy_assign_alloc(const basic_string& __str)
1641        {__copy_assign_alloc(__str, integral_constant<bool,
1642                      __alloc_traits::propagate_on_container_copy_assignment::value>());}
1643
1644    _LIBCPP_INLINE_VISIBILITY
1645    void __copy_assign_alloc(const basic_string& __str, true_type)
1646        {
1647            if (__alloc() == __str.__alloc())
1648                __alloc() = __str.__alloc();
1649            else
1650            {
1651                if (!__str.__is_long())
1652                {
1653                    __clear_and_shrink();
1654                    __alloc() = __str.__alloc();
1655                }
1656                else
1657                {
1658                    allocator_type __a = __str.__alloc();
1659                    pointer __p = __alloc_traits::allocate(__a, __str.__get_long_cap());
1660                    __clear_and_shrink();
1661                    __alloc() = _VSTD::move(__a);
1662                    __set_long_pointer(__p);
1663                    __set_long_cap(__str.__get_long_cap());
1664                    __set_long_size(__str.size());
1665                }
1666            }
1667        }
1668
1669    _LIBCPP_INLINE_VISIBILITY
1670    void __copy_assign_alloc(const basic_string&, false_type) _NOEXCEPT
1671        {}
1672
1673#ifndef _LIBCPP_CXX03_LANG
1674    _LIBCPP_INLINE_VISIBILITY
1675    void __move_assign(basic_string& __str, false_type)
1676        _NOEXCEPT_(__alloc_traits::is_always_equal::value);
1677    _LIBCPP_INLINE_VISIBILITY
1678    void __move_assign(basic_string& __str, true_type)
1679#if _LIBCPP_STD_VER > 14
1680        _NOEXCEPT;
1681#else
1682        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value);
1683#endif
1684#endif
1685
1686    _LIBCPP_INLINE_VISIBILITY
1687    void
1688    __move_assign_alloc(basic_string& __str)
1689        _NOEXCEPT_(
1690            !__alloc_traits::propagate_on_container_move_assignment::value ||
1691            is_nothrow_move_assignable<allocator_type>::value)
1692    {__move_assign_alloc(__str, integral_constant<bool,
1693                      __alloc_traits::propagate_on_container_move_assignment::value>());}
1694
1695    _LIBCPP_INLINE_VISIBILITY
1696    void __move_assign_alloc(basic_string& __c, true_type)
1697        _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
1698        {
1699            __alloc() = _VSTD::move(__c.__alloc());
1700        }
1701
1702    _LIBCPP_INLINE_VISIBILITY
1703    void __move_assign_alloc(basic_string&, false_type)
1704        _NOEXCEPT
1705        {}
1706
1707    basic_string& __assign_external(const value_type* __s);
1708    basic_string& __assign_external(const value_type* __s, size_type __n);
1709
1710    // Assigns the value in __s, guaranteed to be __n < __min_cap in length.
1711    inline basic_string& __assign_short(const value_type* __s, size_type __n) {
1712      pointer __p = __is_long()
1713                        ? (__set_long_size(__n), __get_long_pointer())
1714                        : (__set_short_size(__n), __get_short_pointer());
1715      traits_type::move(_VSTD::__to_address(__p), __s, __n);
1716      traits_type::assign(__p[__n], value_type());
1717      return *this;
1718    }
1719
1720    _LIBCPP_INLINE_VISIBILITY void __invalidate_all_iterators();
1721    _LIBCPP_INLINE_VISIBILITY void __invalidate_iterators_past(size_type);
1722
1723    friend basic_string operator+<>(const basic_string&, const basic_string&);
1724    friend basic_string operator+<>(const value_type*, const basic_string&);
1725    friend basic_string operator+<>(value_type, const basic_string&);
1726    friend basic_string operator+<>(const basic_string&, const value_type*);
1727    friend basic_string operator+<>(const basic_string&, value_type);
1728};
1729
1730// These declarations must appear before any functions are implicitly used
1731// so that they have the correct visibility specifier.
1732#ifdef _LIBCPP_ABI_STRING_OPTIMIZED_EXTERNAL_INSTANTIATION
1733_LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
1734_LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
1735#else
1736_LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, char)
1737_LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_LIBCPP_EXTERN_TEMPLATE, wchar_t)
1738#endif
1739
1740
1741#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
1742template<class _InputIterator,
1743         class _CharT = typename iterator_traits<_InputIterator>::value_type,
1744         class _Allocator = allocator<_CharT>,
1745         class = _EnableIf<__is_cpp17_input_iterator<_InputIterator>::value>,
1746         class = _EnableIf<__is_allocator<_Allocator>::value>
1747         >
1748basic_string(_InputIterator, _InputIterator, _Allocator = _Allocator())
1749  -> basic_string<_CharT, char_traits<_CharT>, _Allocator>;
1750
1751template<class _CharT,
1752         class _Traits,
1753         class _Allocator = allocator<_CharT>,
1754         class = _EnableIf<__is_allocator<_Allocator>::value>
1755         >
1756explicit basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
1757  -> basic_string<_CharT, _Traits, _Allocator>;
1758
1759template<class _CharT,
1760         class _Traits,
1761         class _Allocator = allocator<_CharT>,
1762         class = _EnableIf<__is_allocator<_Allocator>::value>,
1763         class _Sz = typename allocator_traits<_Allocator>::size_type
1764         >
1765basic_string(basic_string_view<_CharT, _Traits>, _Sz, _Sz, const _Allocator& = _Allocator())
1766  -> basic_string<_CharT, _Traits, _Allocator>;
1767#endif
1768
1769template <class _CharT, class _Traits, class _Allocator>
1770inline
1771void
1772basic_string<_CharT, _Traits, _Allocator>::__invalidate_all_iterators()
1773{
1774#if _LIBCPP_DEBUG_LEVEL == 2
1775    __get_db()->__invalidate_all(this);
1776#endif
1777}
1778
1779template <class _CharT, class _Traits, class _Allocator>
1780inline
1781void
1782basic_string<_CharT, _Traits, _Allocator>::__invalidate_iterators_past(size_type
1783#if _LIBCPP_DEBUG_LEVEL == 2
1784                                                                        __pos
1785#endif
1786                                                                      )
1787{
1788#if _LIBCPP_DEBUG_LEVEL == 2
1789    __c_node* __c = __get_db()->__find_c_and_lock(this);
1790    if (__c)
1791    {
1792        const_pointer __new_last = __get_pointer() + __pos;
1793        for (__i_node** __p = __c->end_; __p != __c->beg_; )
1794        {
1795            --__p;
1796            const_iterator* __i = static_cast<const_iterator*>((*__p)->__i_);
1797            if (__i->base() > __new_last)
1798            {
1799                (*__p)->__c_ = nullptr;
1800                if (--__c->end_ != __p)
1801                    _VSTD::memmove(__p, __p+1, (__c->end_ - __p)*sizeof(__i_node*));
1802            }
1803        }
1804        __get_db()->unlock();
1805    }
1806#endif  // _LIBCPP_DEBUG_LEVEL == 2
1807}
1808
1809template <class _CharT, class _Traits, class _Allocator>
1810inline
1811basic_string<_CharT, _Traits, _Allocator>::basic_string()
1812    _NOEXCEPT_(is_nothrow_default_constructible<allocator_type>::value)
1813     : __r_(__default_init_tag(), __default_init_tag())
1814{
1815#if _LIBCPP_DEBUG_LEVEL == 2
1816    __get_db()->__insert_c(this);
1817#endif
1818    __zero();
1819}
1820
1821template <class _CharT, class _Traits, class _Allocator>
1822inline
1823basic_string<_CharT, _Traits, _Allocator>::basic_string(const allocator_type& __a)
1824#if _LIBCPP_STD_VER <= 14
1825        _NOEXCEPT_(is_nothrow_copy_constructible<allocator_type>::value)
1826#else
1827        _NOEXCEPT
1828#endif
1829: __r_(__default_init_tag(), __a)
1830{
1831#if _LIBCPP_DEBUG_LEVEL == 2
1832    __get_db()->__insert_c(this);
1833#endif
1834    __zero();
1835}
1836
1837template <class _CharT, class _Traits, class _Allocator>
1838void basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s,
1839                                                       size_type __sz,
1840                                                       size_type __reserve)
1841{
1842    if (__reserve > max_size())
1843        this->__throw_length_error();
1844    pointer __p;
1845    if (__reserve < __min_cap)
1846    {
1847        __set_short_size(__sz);
1848        __p = __get_short_pointer();
1849    }
1850    else
1851    {
1852        size_type __cap = __recommend(__reserve);
1853        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1854        __set_long_pointer(__p);
1855        __set_long_cap(__cap+1);
1856        __set_long_size(__sz);
1857    }
1858    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1859    traits_type::assign(__p[__sz], value_type());
1860}
1861
1862template <class _CharT, class _Traits, class _Allocator>
1863void
1864basic_string<_CharT, _Traits, _Allocator>::__init(const value_type* __s, size_type __sz)
1865{
1866    if (__sz > max_size())
1867        this->__throw_length_error();
1868    pointer __p;
1869    if (__sz < __min_cap)
1870    {
1871        __set_short_size(__sz);
1872        __p = __get_short_pointer();
1873    }
1874    else
1875    {
1876        size_type __cap = __recommend(__sz);
1877        __p = __alloc_traits::allocate(__alloc(), __cap+1);
1878        __set_long_pointer(__p);
1879        __set_long_cap(__cap+1);
1880        __set_long_size(__sz);
1881    }
1882    traits_type::copy(_VSTD::__to_address(__p), __s, __sz);
1883    traits_type::assign(__p[__sz], value_type());
1884}
1885
1886template <class _CharT, class _Traits, class _Allocator>
1887template <class>
1888basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, const _Allocator& __a)
1889    : __r_(__default_init_tag(), __a)
1890{
1891    _LIBCPP_ASSERT(__s != nullptr, "basic_string(const char*, allocator) detected nullptr");
1892    __init(__s, traits_type::length(__s));
1893#if _LIBCPP_DEBUG_LEVEL == 2
1894    __get_db()->__insert_c(this);
1895#endif
1896}
1897
1898template <class _CharT, class _Traits, class _Allocator>
1899inline
1900basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n)
1901     : __r_(__default_init_tag(), __default_init_tag())
1902{
1903    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n) detected nullptr");
1904    __init(__s, __n);
1905#if _LIBCPP_DEBUG_LEVEL == 2
1906    __get_db()->__insert_c(this);
1907#endif
1908}
1909
1910template <class _CharT, class _Traits, class _Allocator>
1911inline
1912basic_string<_CharT, _Traits, _Allocator>::basic_string(const _CharT* __s, size_type __n, const _Allocator& __a)
1913    : __r_(__default_init_tag(), __a)
1914{
1915    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "basic_string(const char*, n, allocator) detected nullptr");
1916    __init(__s, __n);
1917#if _LIBCPP_DEBUG_LEVEL == 2
1918    __get_db()->__insert_c(this);
1919#endif
1920}
1921
1922template <class _CharT, class _Traits, class _Allocator>
1923basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str)
1924    : __r_(__default_init_tag(), __alloc_traits::select_on_container_copy_construction(__str.__alloc()))
1925{
1926    if (!__str.__is_long())
1927        __r_.first().__r = __str.__r_.first().__r;
1928    else
1929        __init_copy_ctor_external(_VSTD::__to_address(__str.__get_long_pointer()),
1930                                  __str.__get_long_size());
1931
1932#if _LIBCPP_DEBUG_LEVEL == 2
1933    __get_db()->__insert_c(this);
1934#endif
1935}
1936
1937template <class _CharT, class _Traits, class _Allocator>
1938basic_string<_CharT, _Traits, _Allocator>::basic_string(
1939    const basic_string& __str, const allocator_type& __a)
1940    : __r_(__default_init_tag(), __a)
1941{
1942    if (!__str.__is_long())
1943        __r_.first().__r = __str.__r_.first().__r;
1944    else
1945        __init_copy_ctor_external(_VSTD::__to_address(__str.__get_long_pointer()),
1946                                  __str.__get_long_size());
1947#if _LIBCPP_DEBUG_LEVEL == 2
1948    __get_db()->__insert_c(this);
1949#endif
1950}
1951
1952template <class _CharT, class _Traits, class _Allocator>
1953void basic_string<_CharT, _Traits, _Allocator>::__init_copy_ctor_external(
1954    const value_type* __s, size_type __sz) {
1955  pointer __p;
1956  if (__sz < __min_cap) {
1957    __p = __get_short_pointer();
1958    __set_short_size(__sz);
1959  } else {
1960    if (__sz > max_size())
1961      this->__throw_length_error();
1962    size_t __cap = __recommend(__sz);
1963    __p = __alloc_traits::allocate(__alloc(), __cap + 1);
1964    __set_long_pointer(__p);
1965    __set_long_cap(__cap + 1);
1966    __set_long_size(__sz);
1967  }
1968  traits_type::copy(_VSTD::__to_address(__p), __s, __sz + 1);
1969}
1970
1971#ifndef _LIBCPP_CXX03_LANG
1972
1973template <class _CharT, class _Traits, class _Allocator>
1974inline
1975basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str)
1976#if _LIBCPP_STD_VER <= 14
1977        _NOEXCEPT_(is_nothrow_move_constructible<allocator_type>::value)
1978#else
1979        _NOEXCEPT
1980#endif
1981    : __r_(_VSTD::move(__str.__r_))
1982{
1983    __str.__zero();
1984#if _LIBCPP_DEBUG_LEVEL == 2
1985    __get_db()->__insert_c(this);
1986    if (__is_long())
1987        __get_db()->swap(this, &__str);
1988#endif
1989}
1990
1991template <class _CharT, class _Traits, class _Allocator>
1992inline
1993basic_string<_CharT, _Traits, _Allocator>::basic_string(basic_string&& __str, const allocator_type& __a)
1994    : __r_(__default_init_tag(), __a)
1995{
1996    if (__str.__is_long() && __a != __str.__alloc()) // copy, not move
1997        __init(_VSTD::__to_address(__str.__get_long_pointer()), __str.__get_long_size());
1998    else
1999    {
2000        __r_.first().__r = __str.__r_.first().__r;
2001        __str.__zero();
2002    }
2003#if _LIBCPP_DEBUG_LEVEL == 2
2004    __get_db()->__insert_c(this);
2005    if (__is_long())
2006        __get_db()->swap(this, &__str);
2007#endif
2008}
2009
2010#endif  // _LIBCPP_CXX03_LANG
2011
2012template <class _CharT, class _Traits, class _Allocator>
2013void
2014basic_string<_CharT, _Traits, _Allocator>::__init(size_type __n, value_type __c)
2015{
2016    if (__n > max_size())
2017        this->__throw_length_error();
2018    pointer __p;
2019    if (__n < __min_cap)
2020    {
2021        __set_short_size(__n);
2022        __p = __get_short_pointer();
2023    }
2024    else
2025    {
2026        size_type __cap = __recommend(__n);
2027        __p = __alloc_traits::allocate(__alloc(), __cap+1);
2028        __set_long_pointer(__p);
2029        __set_long_cap(__cap+1);
2030        __set_long_size(__n);
2031    }
2032    traits_type::assign(_VSTD::__to_address(__p), __n, __c);
2033    traits_type::assign(__p[__n], value_type());
2034}
2035
2036template <class _CharT, class _Traits, class _Allocator>
2037inline
2038basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c)
2039     : __r_(__default_init_tag(), __default_init_tag())
2040{
2041    __init(__n, __c);
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>
2049basic_string<_CharT, _Traits, _Allocator>::basic_string(size_type __n, _CharT __c, const _Allocator& __a)
2050    : __r_(__default_init_tag(), __a)
2051{
2052    __init(__n, __c);
2053#if _LIBCPP_DEBUG_LEVEL == 2
2054    __get_db()->__insert_c(this);
2055#endif
2056}
2057
2058template <class _CharT, class _Traits, class _Allocator>
2059basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str,
2060                                                        size_type __pos, size_type __n,
2061                                                        const _Allocator& __a)
2062    : __r_(__default_init_tag(), __a)
2063{
2064    size_type __str_sz = __str.size();
2065    if (__pos > __str_sz)
2066        this->__throw_out_of_range();
2067    __init(__str.data() + __pos, _VSTD::min(__n, __str_sz - __pos));
2068#if _LIBCPP_DEBUG_LEVEL == 2
2069    __get_db()->__insert_c(this);
2070#endif
2071}
2072
2073template <class _CharT, class _Traits, class _Allocator>
2074inline
2075basic_string<_CharT, _Traits, _Allocator>::basic_string(const basic_string& __str, size_type __pos,
2076                                                        const _Allocator& __a)
2077    : __r_(__default_init_tag(), __a)
2078{
2079    size_type __str_sz = __str.size();
2080    if (__pos > __str_sz)
2081        this->__throw_out_of_range();
2082    __init(__str.data() + __pos, __str_sz - __pos);
2083#if _LIBCPP_DEBUG_LEVEL == 2
2084    __get_db()->__insert_c(this);
2085#endif
2086}
2087
2088template <class _CharT, class _Traits, class _Allocator>
2089template <class _Tp, class>
2090basic_string<_CharT, _Traits, _Allocator>::basic_string(
2091             const _Tp& __t, size_type __pos, size_type __n, const allocator_type& __a)
2092    : __r_(__default_init_tag(), __a)
2093{
2094    __self_view __sv0 = __t;
2095    __self_view __sv = __sv0.substr(__pos, __n);
2096    __init(__sv.data(), __sv.size());
2097#if _LIBCPP_DEBUG_LEVEL == 2
2098    __get_db()->__insert_c(this);
2099#endif
2100}
2101
2102template <class _CharT, class _Traits, class _Allocator>
2103template <class _Tp, class>
2104basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t)
2105     : __r_(__default_init_tag(), __default_init_tag())
2106{
2107    __self_view __sv = __t;
2108    __init(__sv.data(), __sv.size());
2109#if _LIBCPP_DEBUG_LEVEL == 2
2110    __get_db()->__insert_c(this);
2111#endif
2112}
2113
2114template <class _CharT, class _Traits, class _Allocator>
2115template <class _Tp, class>
2116basic_string<_CharT, _Traits, _Allocator>::basic_string(const _Tp & __t, const _Allocator& __a)
2117    : __r_(__default_init_tag(), __a)
2118{
2119    __self_view __sv = __t;
2120    __init(__sv.data(), __sv.size());
2121#if _LIBCPP_DEBUG_LEVEL == 2
2122    __get_db()->__insert_c(this);
2123#endif
2124}
2125
2126template <class _CharT, class _Traits, class _Allocator>
2127template <class _InputIterator>
2128_EnableIf
2129<
2130    __is_exactly_cpp17_input_iterator<_InputIterator>::value
2131>
2132basic_string<_CharT, _Traits, _Allocator>::__init(_InputIterator __first, _InputIterator __last)
2133{
2134    __zero();
2135#ifndef _LIBCPP_NO_EXCEPTIONS
2136    try
2137    {
2138#endif  // _LIBCPP_NO_EXCEPTIONS
2139    for (; __first != __last; ++__first)
2140        push_back(*__first);
2141#ifndef _LIBCPP_NO_EXCEPTIONS
2142    }
2143    catch (...)
2144    {
2145        if (__is_long())
2146            __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2147        throw;
2148    }
2149#endif  // _LIBCPP_NO_EXCEPTIONS
2150}
2151
2152template <class _CharT, class _Traits, class _Allocator>
2153template <class _ForwardIterator>
2154_EnableIf
2155<
2156    __is_cpp17_forward_iterator<_ForwardIterator>::value
2157>
2158basic_string<_CharT, _Traits, _Allocator>::__init(_ForwardIterator __first, _ForwardIterator __last)
2159{
2160    size_type __sz = static_cast<size_type>(_VSTD::distance(__first, __last));
2161    if (__sz > max_size())
2162        this->__throw_length_error();
2163    pointer __p;
2164    if (__sz < __min_cap)
2165    {
2166        __set_short_size(__sz);
2167        __p = __get_short_pointer();
2168    }
2169    else
2170    {
2171        size_type __cap = __recommend(__sz);
2172        __p = __alloc_traits::allocate(__alloc(), __cap+1);
2173        __set_long_pointer(__p);
2174        __set_long_cap(__cap+1);
2175        __set_long_size(__sz);
2176    }
2177    for (; __first != __last; ++__first, (void) ++__p)
2178        traits_type::assign(*__p, *__first);
2179    traits_type::assign(*__p, value_type());
2180}
2181
2182template <class _CharT, class _Traits, class _Allocator>
2183template<class _InputIterator, class>
2184inline
2185basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last)
2186     : __r_(__default_init_tag(), __default_init_tag())
2187{
2188    __init(__first, __last);
2189#if _LIBCPP_DEBUG_LEVEL == 2
2190    __get_db()->__insert_c(this);
2191#endif
2192}
2193
2194template <class _CharT, class _Traits, class _Allocator>
2195template<class _InputIterator, class>
2196inline
2197basic_string<_CharT, _Traits, _Allocator>::basic_string(_InputIterator __first, _InputIterator __last,
2198                                                        const allocator_type& __a)
2199    : __r_(__default_init_tag(), __a)
2200{
2201    __init(__first, __last);
2202#if _LIBCPP_DEBUG_LEVEL == 2
2203    __get_db()->__insert_c(this);
2204#endif
2205}
2206
2207#ifndef _LIBCPP_CXX03_LANG
2208
2209template <class _CharT, class _Traits, class _Allocator>
2210inline
2211basic_string<_CharT, _Traits, _Allocator>::basic_string(
2212    initializer_list<_CharT> __il)
2213     : __r_(__default_init_tag(), __default_init_tag())
2214{
2215    __init(__il.begin(), __il.end());
2216#if _LIBCPP_DEBUG_LEVEL == 2
2217    __get_db()->__insert_c(this);
2218#endif
2219}
2220
2221template <class _CharT, class _Traits, class _Allocator>
2222inline
2223
2224basic_string<_CharT, _Traits, _Allocator>::basic_string(
2225    initializer_list<_CharT> __il, const _Allocator& __a)
2226    : __r_(__default_init_tag(), __a)
2227{
2228    __init(__il.begin(), __il.end());
2229#if _LIBCPP_DEBUG_LEVEL == 2
2230    __get_db()->__insert_c(this);
2231#endif
2232}
2233
2234#endif  // _LIBCPP_CXX03_LANG
2235
2236template <class _CharT, class _Traits, class _Allocator>
2237basic_string<_CharT, _Traits, _Allocator>::~basic_string()
2238{
2239#if _LIBCPP_DEBUG_LEVEL == 2
2240    __get_db()->__erase_c(this);
2241#endif
2242    if (__is_long())
2243        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), __get_long_cap());
2244}
2245
2246template <class _CharT, class _Traits, class _Allocator>
2247void
2248basic_string<_CharT, _Traits, _Allocator>::__grow_by_and_replace
2249    (size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2250     size_type __n_copy,  size_type __n_del,     size_type __n_add, const value_type* __p_new_stuff)
2251{
2252    size_type __ms = max_size();
2253    if (__delta_cap > __ms - __old_cap - 1)
2254        this->__throw_length_error();
2255    pointer __old_p = __get_pointer();
2256    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2257                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2258                          __ms - 1;
2259    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2260    __invalidate_all_iterators();
2261    if (__n_copy != 0)
2262        traits_type::copy(_VSTD::__to_address(__p),
2263                          _VSTD::__to_address(__old_p), __n_copy);
2264    if (__n_add != 0)
2265        traits_type::copy(_VSTD::__to_address(__p) + __n_copy, __p_new_stuff, __n_add);
2266    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2267    if (__sec_cp_sz != 0)
2268        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2269                          _VSTD::__to_address(__old_p) + __n_copy + __n_del, __sec_cp_sz);
2270    if (__old_cap+1 != __min_cap)
2271        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2272    __set_long_pointer(__p);
2273    __set_long_cap(__cap+1);
2274    __old_sz = __n_copy + __n_add + __sec_cp_sz;
2275    __set_long_size(__old_sz);
2276    traits_type::assign(__p[__old_sz], value_type());
2277}
2278
2279template <class _CharT, class _Traits, class _Allocator>
2280void
2281basic_string<_CharT, _Traits, _Allocator>::__grow_by(size_type __old_cap, size_type __delta_cap, size_type __old_sz,
2282                                                     size_type __n_copy,  size_type __n_del,     size_type __n_add)
2283{
2284    size_type __ms = max_size();
2285    if (__delta_cap > __ms - __old_cap)
2286        this->__throw_length_error();
2287    pointer __old_p = __get_pointer();
2288    size_type __cap = __old_cap < __ms / 2 - __alignment ?
2289                          __recommend(_VSTD::max(__old_cap + __delta_cap, 2 * __old_cap)) :
2290                          __ms - 1;
2291    pointer __p = __alloc_traits::allocate(__alloc(), __cap+1);
2292    __invalidate_all_iterators();
2293    if (__n_copy != 0)
2294        traits_type::copy(_VSTD::__to_address(__p),
2295                          _VSTD::__to_address(__old_p), __n_copy);
2296    size_type __sec_cp_sz = __old_sz - __n_del - __n_copy;
2297    if (__sec_cp_sz != 0)
2298        traits_type::copy(_VSTD::__to_address(__p) + __n_copy + __n_add,
2299                          _VSTD::__to_address(__old_p) + __n_copy + __n_del,
2300                          __sec_cp_sz);
2301    if (__old_cap+1 != __min_cap)
2302        __alloc_traits::deallocate(__alloc(), __old_p, __old_cap+1);
2303    __set_long_pointer(__p);
2304    __set_long_cap(__cap+1);
2305}
2306
2307// assign
2308
2309template <class _CharT, class _Traits, class _Allocator>
2310template <bool __is_short>
2311basic_string<_CharT, _Traits, _Allocator>&
2312basic_string<_CharT, _Traits, _Allocator>::__assign_no_alias(
2313    const value_type* __s, size_type __n) {
2314  size_type __cap = __is_short ? __min_cap : __get_long_cap();
2315  if (__n < __cap) {
2316    pointer __p = __is_short ? __get_short_pointer() : __get_long_pointer();
2317    __is_short ? __set_short_size(__n) : __set_long_size(__n);
2318    traits_type::copy(_VSTD::__to_address(__p), __s, __n);
2319    traits_type::assign(__p[__n], value_type());
2320    __invalidate_iterators_past(__n);
2321  } else {
2322    size_type __sz = __is_short ? __get_short_size() : __get_long_size();
2323    __grow_by_and_replace(__cap - 1, __n - __cap + 1, __sz, 0, __sz, __n, __s);
2324  }
2325  return *this;
2326}
2327
2328template <class _CharT, class _Traits, class _Allocator>
2329basic_string<_CharT, _Traits, _Allocator>&
2330basic_string<_CharT, _Traits, _Allocator>::__assign_external(
2331    const value_type* __s, size_type __n) {
2332  size_type __cap = capacity();
2333  if (__cap >= __n) {
2334    value_type* __p = _VSTD::__to_address(__get_pointer());
2335    traits_type::move(__p, __s, __n);
2336    traits_type::assign(__p[__n], value_type());
2337    __set_size(__n);
2338    __invalidate_iterators_past(__n);
2339  } else {
2340    size_type __sz = size();
2341    __grow_by_and_replace(__cap, __n - __cap, __sz, 0, __sz, __n, __s);
2342  }
2343  return *this;
2344}
2345
2346template <class _CharT, class _Traits, class _Allocator>
2347basic_string<_CharT, _Traits, _Allocator>&
2348basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s, size_type __n)
2349{
2350    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::assign received nullptr");
2351    return (_LIBCPP_BUILTIN_CONSTANT_P(__n) && __n < __min_cap)
2352               ? __assign_short(__s, __n)
2353               : __assign_external(__s, __n);
2354}
2355
2356template <class _CharT, class _Traits, class _Allocator>
2357basic_string<_CharT, _Traits, _Allocator>&
2358basic_string<_CharT, _Traits, _Allocator>::assign(size_type __n, value_type __c)
2359{
2360    size_type __cap = capacity();
2361    if (__cap < __n)
2362    {
2363        size_type __sz = size();
2364        __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2365    }
2366    else
2367        __invalidate_iterators_past(__n);
2368    value_type* __p = _VSTD::__to_address(__get_pointer());
2369    traits_type::assign(__p, __n, __c);
2370    traits_type::assign(__p[__n], value_type());
2371    __set_size(__n);
2372    return *this;
2373}
2374
2375template <class _CharT, class _Traits, class _Allocator>
2376basic_string<_CharT, _Traits, _Allocator>&
2377basic_string<_CharT, _Traits, _Allocator>::operator=(value_type __c)
2378{
2379    pointer __p;
2380    if (__is_long())
2381    {
2382        __p = __get_long_pointer();
2383        __set_long_size(1);
2384    }
2385    else
2386    {
2387        __p = __get_short_pointer();
2388        __set_short_size(1);
2389    }
2390    traits_type::assign(*__p, __c);
2391    traits_type::assign(*++__p, value_type());
2392    __invalidate_iterators_past(1);
2393    return *this;
2394}
2395
2396template <class _CharT, class _Traits, class _Allocator>
2397basic_string<_CharT, _Traits, _Allocator>&
2398basic_string<_CharT, _Traits, _Allocator>::operator=(const basic_string& __str)
2399{
2400  if (this != &__str) {
2401    __copy_assign_alloc(__str);
2402    if (!__is_long()) {
2403      if (!__str.__is_long()) {
2404        __r_.first().__r = __str.__r_.first().__r;
2405      } else {
2406        return __assign_no_alias<true>(__str.data(), __str.size());
2407      }
2408    } else {
2409      return __assign_no_alias<false>(__str.data(), __str.size());
2410    }
2411  }
2412  return *this;
2413}
2414
2415#ifndef _LIBCPP_CXX03_LANG
2416
2417template <class _CharT, class _Traits, class _Allocator>
2418inline
2419void
2420basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, false_type)
2421    _NOEXCEPT_(__alloc_traits::is_always_equal::value)
2422{
2423    if (__alloc() != __str.__alloc())
2424        assign(__str);
2425    else
2426        __move_assign(__str, true_type());
2427}
2428
2429template <class _CharT, class _Traits, class _Allocator>
2430inline
2431void
2432basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, true_type)
2433#if _LIBCPP_STD_VER > 14
2434    _NOEXCEPT
2435#else
2436    _NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
2437#endif
2438{
2439  if (__is_long()) {
2440    __alloc_traits::deallocate(__alloc(), __get_long_pointer(),
2441                               __get_long_cap());
2442#if _LIBCPP_STD_VER <= 14
2443    if (!is_nothrow_move_assignable<allocator_type>::value) {
2444      __set_short_size(0);
2445      traits_type::assign(__get_short_pointer()[0], value_type());
2446    }
2447#endif
2448  }
2449  __move_assign_alloc(__str);
2450  __r_.first() = __str.__r_.first();
2451  __str.__set_short_size(0);
2452  traits_type::assign(__str.__get_short_pointer()[0], value_type());
2453}
2454
2455template <class _CharT, class _Traits, class _Allocator>
2456inline
2457basic_string<_CharT, _Traits, _Allocator>&
2458basic_string<_CharT, _Traits, _Allocator>::operator=(basic_string&& __str)
2459    _NOEXCEPT_((__noexcept_move_assign_container<_Allocator, __alloc_traits>::value))
2460{
2461    __move_assign(__str, integral_constant<bool,
2462          __alloc_traits::propagate_on_container_move_assignment::value>());
2463    return *this;
2464}
2465
2466#endif
2467
2468template <class _CharT, class _Traits, class _Allocator>
2469template<class _InputIterator>
2470_EnableIf
2471<
2472     __is_exactly_cpp17_input_iterator <_InputIterator>::value
2473          || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
2474    basic_string<_CharT, _Traits, _Allocator>&
2475>
2476basic_string<_CharT, _Traits, _Allocator>::assign(_InputIterator __first, _InputIterator __last)
2477{
2478    const basic_string __temp(__first, __last, __alloc());
2479    assign(__temp.data(), __temp.size());
2480    return *this;
2481}
2482
2483template <class _CharT, class _Traits, class _Allocator>
2484template<class _ForwardIterator>
2485_EnableIf
2486<
2487    __is_cpp17_forward_iterator<_ForwardIterator>::value
2488         && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
2489    basic_string<_CharT, _Traits, _Allocator>&
2490>
2491basic_string<_CharT, _Traits, _Allocator>::assign(_ForwardIterator __first, _ForwardIterator __last)
2492{
2493    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2494    size_type __cap = capacity();
2495    if (__cap < __n)
2496    {
2497        size_type __sz = size();
2498        __grow_by(__cap, __n - __cap, __sz, 0, __sz);
2499    }
2500    else
2501        __invalidate_iterators_past(__n);
2502    pointer __p = __get_pointer();
2503    for (; __first != __last; ++__first, ++__p)
2504        traits_type::assign(*__p, *__first);
2505    traits_type::assign(*__p, value_type());
2506    __set_size(__n);
2507    return *this;
2508}
2509
2510template <class _CharT, class _Traits, class _Allocator>
2511basic_string<_CharT, _Traits, _Allocator>&
2512basic_string<_CharT, _Traits, _Allocator>::assign(const basic_string& __str, size_type __pos, size_type __n)
2513{
2514    size_type __sz = __str.size();
2515    if (__pos > __sz)
2516        this->__throw_out_of_range();
2517    return assign(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2518}
2519
2520template <class _CharT, class _Traits, class _Allocator>
2521template <class _Tp>
2522_EnableIf
2523<
2524    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
2525    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2526    basic_string<_CharT, _Traits, _Allocator>&
2527>
2528basic_string<_CharT, _Traits, _Allocator>::assign(const _Tp & __t, size_type __pos, size_type __n)
2529{
2530    __self_view __sv = __t;
2531    size_type __sz = __sv.size();
2532    if (__pos > __sz)
2533        this->__throw_out_of_range();
2534    return assign(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2535}
2536
2537
2538template <class _CharT, class _Traits, class _Allocator>
2539basic_string<_CharT, _Traits, _Allocator>&
2540basic_string<_CharT, _Traits, _Allocator>::__assign_external(const value_type* __s) {
2541  return __assign_external(__s, traits_type::length(__s));
2542}
2543
2544template <class _CharT, class _Traits, class _Allocator>
2545basic_string<_CharT, _Traits, _Allocator>&
2546basic_string<_CharT, _Traits, _Allocator>::assign(const value_type* __s)
2547{
2548    _LIBCPP_ASSERT(__s != nullptr, "string::assign received nullptr");
2549    return _LIBCPP_BUILTIN_CONSTANT_P(*__s)
2550               ? (traits_type::length(__s) < __min_cap
2551                      ? __assign_short(__s, traits_type::length(__s))
2552                      : __assign_external(__s, traits_type::length(__s)))
2553               : __assign_external(__s);
2554}
2555// append
2556
2557template <class _CharT, class _Traits, class _Allocator>
2558basic_string<_CharT, _Traits, _Allocator>&
2559basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s, size_type __n)
2560{
2561    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::append received nullptr");
2562    size_type __cap = capacity();
2563    size_type __sz = size();
2564    if (__cap - __sz >= __n)
2565    {
2566        if (__n)
2567        {
2568            value_type* __p = _VSTD::__to_address(__get_pointer());
2569            traits_type::copy(__p + __sz, __s, __n);
2570            __sz += __n;
2571            __set_size(__sz);
2572            traits_type::assign(__p[__sz], value_type());
2573        }
2574    }
2575    else
2576        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __sz, 0, __n, __s);
2577    return *this;
2578}
2579
2580template <class _CharT, class _Traits, class _Allocator>
2581basic_string<_CharT, _Traits, _Allocator>&
2582basic_string<_CharT, _Traits, _Allocator>::append(size_type __n, value_type __c)
2583{
2584    if (__n)
2585    {
2586        size_type __cap = capacity();
2587        size_type __sz = size();
2588        if (__cap - __sz < __n)
2589            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2590        pointer __p = __get_pointer();
2591        traits_type::assign(_VSTD::__to_address(__p) + __sz, __n, __c);
2592        __sz += __n;
2593        __set_size(__sz);
2594        traits_type::assign(__p[__sz], value_type());
2595    }
2596    return *this;
2597}
2598
2599template <class _CharT, class _Traits, class _Allocator>
2600inline void
2601basic_string<_CharT, _Traits, _Allocator>::__append_default_init(size_type __n)
2602{
2603    if (__n)
2604    {
2605        size_type __cap = capacity();
2606        size_type __sz = size();
2607        if (__cap - __sz < __n)
2608            __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2609        pointer __p = __get_pointer();
2610        __sz += __n;
2611        __set_size(__sz);
2612        traits_type::assign(__p[__sz], value_type());
2613    }
2614}
2615
2616template <class _CharT, class _Traits, class _Allocator>
2617void
2618basic_string<_CharT, _Traits, _Allocator>::push_back(value_type __c)
2619{
2620    bool __is_short = !__is_long();
2621    size_type __cap;
2622    size_type __sz;
2623    if (__is_short)
2624    {
2625        __cap = __min_cap - 1;
2626        __sz = __get_short_size();
2627    }
2628    else
2629    {
2630        __cap = __get_long_cap() - 1;
2631        __sz = __get_long_size();
2632    }
2633    if (__sz == __cap)
2634    {
2635        __grow_by(__cap, 1, __sz, __sz, 0);
2636        __is_short = !__is_long();
2637    }
2638    pointer __p;
2639    if (__is_short)
2640    {
2641        __p = __get_short_pointer() + __sz;
2642        __set_short_size(__sz+1);
2643    }
2644    else
2645    {
2646        __p = __get_long_pointer() + __sz;
2647        __set_long_size(__sz+1);
2648    }
2649    traits_type::assign(*__p, __c);
2650    traits_type::assign(*++__p, value_type());
2651}
2652
2653template <class _Tp>
2654bool __ptr_in_range (const _Tp* __p, const _Tp* __first, const _Tp* __last)
2655{
2656    return __first <= __p && __p < __last;
2657}
2658
2659template <class _Tp1, class _Tp2>
2660bool __ptr_in_range (const _Tp1*, const _Tp2*, const _Tp2*)
2661{
2662    return false;
2663}
2664
2665template <class _CharT, class _Traits, class _Allocator>
2666template<class _ForwardIterator>
2667basic_string<_CharT, _Traits, _Allocator>&
2668basic_string<_CharT, _Traits, _Allocator>::__append_forward_unsafe(
2669    _ForwardIterator __first, _ForwardIterator __last)
2670{
2671    static_assert(__is_cpp17_forward_iterator<_ForwardIterator>::value,
2672                  "function requires a ForwardIterator");
2673    size_type __sz = size();
2674    size_type __cap = capacity();
2675    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2676    if (__n)
2677    {
2678        typedef typename iterator_traits<_ForwardIterator>::reference _CharRef;
2679        _CharRef __tmp_ref = *__first;
2680        if (__ptr_in_range(_VSTD::addressof(__tmp_ref), data(), data() + size()))
2681        {
2682            const basic_string __temp (__first, __last, __alloc());
2683            append(__temp.data(), __temp.size());
2684        }
2685        else
2686        {
2687            if (__cap - __sz < __n)
2688                __grow_by(__cap, __sz + __n - __cap, __sz, __sz, 0);
2689            pointer __p = __get_pointer() + __sz;
2690            for (; __first != __last; ++__p, ++__first)
2691                traits_type::assign(*__p, *__first);
2692            traits_type::assign(*__p, value_type());
2693            __set_size(__sz + __n);
2694        }
2695    }
2696    return *this;
2697}
2698
2699template <class _CharT, class _Traits, class _Allocator>
2700inline
2701basic_string<_CharT, _Traits, _Allocator>&
2702basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str)
2703{
2704    return append(__str.data(), __str.size());
2705}
2706
2707template <class _CharT, class _Traits, class _Allocator>
2708basic_string<_CharT, _Traits, _Allocator>&
2709basic_string<_CharT, _Traits, _Allocator>::append(const basic_string& __str, size_type __pos, size_type __n)
2710{
2711    size_type __sz = __str.size();
2712    if (__pos > __sz)
2713        this->__throw_out_of_range();
2714    return append(__str.data() + __pos, _VSTD::min(__n, __sz - __pos));
2715}
2716
2717template <class _CharT, class _Traits, class _Allocator>
2718template <class _Tp>
2719    _EnableIf
2720    <
2721        __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2722        basic_string<_CharT, _Traits, _Allocator>&
2723    >
2724basic_string<_CharT, _Traits, _Allocator>::append(const _Tp & __t, size_type __pos, size_type __n)
2725{
2726    __self_view __sv = __t;
2727    size_type __sz = __sv.size();
2728    if (__pos > __sz)
2729        this->__throw_out_of_range();
2730    return append(__sv.data() + __pos, _VSTD::min(__n, __sz - __pos));
2731}
2732
2733template <class _CharT, class _Traits, class _Allocator>
2734basic_string<_CharT, _Traits, _Allocator>&
2735basic_string<_CharT, _Traits, _Allocator>::append(const value_type* __s)
2736{
2737    _LIBCPP_ASSERT(__s != nullptr, "string::append received nullptr");
2738    return append(__s, traits_type::length(__s));
2739}
2740
2741// insert
2742
2743template <class _CharT, class _Traits, class _Allocator>
2744basic_string<_CharT, _Traits, _Allocator>&
2745basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s, size_type __n)
2746{
2747    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::insert received nullptr");
2748    size_type __sz = size();
2749    if (__pos > __sz)
2750        this->__throw_out_of_range();
2751    size_type __cap = capacity();
2752    if (__cap - __sz >= __n)
2753    {
2754        if (__n)
2755        {
2756            value_type* __p = _VSTD::__to_address(__get_pointer());
2757            size_type __n_move = __sz - __pos;
2758            if (__n_move != 0)
2759            {
2760                if (__p + __pos <= __s && __s < __p + __sz)
2761                    __s += __n;
2762                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2763            }
2764            traits_type::move(__p + __pos, __s, __n);
2765            __sz += __n;
2766            __set_size(__sz);
2767            traits_type::assign(__p[__sz], value_type());
2768        }
2769    }
2770    else
2771        __grow_by_and_replace(__cap, __sz + __n - __cap, __sz, __pos, 0, __n, __s);
2772    return *this;
2773}
2774
2775template <class _CharT, class _Traits, class _Allocator>
2776basic_string<_CharT, _Traits, _Allocator>&
2777basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, size_type __n, value_type __c)
2778{
2779    size_type __sz = size();
2780    if (__pos > __sz)
2781        this->__throw_out_of_range();
2782    if (__n)
2783    {
2784        size_type __cap = capacity();
2785        value_type* __p;
2786        if (__cap - __sz >= __n)
2787        {
2788            __p = _VSTD::__to_address(__get_pointer());
2789            size_type __n_move = __sz - __pos;
2790            if (__n_move != 0)
2791                traits_type::move(__p + __pos + __n, __p + __pos, __n_move);
2792        }
2793        else
2794        {
2795            __grow_by(__cap, __sz + __n - __cap, __sz, __pos, 0, __n);
2796            __p = _VSTD::__to_address(__get_long_pointer());
2797        }
2798        traits_type::assign(__p + __pos, __n, __c);
2799        __sz += __n;
2800        __set_size(__sz);
2801        traits_type::assign(__p[__sz], value_type());
2802    }
2803    return *this;
2804}
2805
2806template <class _CharT, class _Traits, class _Allocator>
2807template<class _InputIterator>
2808_EnableIf
2809<
2810   __is_exactly_cpp17_input_iterator<_InputIterator>::value
2811        || !__libcpp_string_gets_noexcept_iterator<_InputIterator>::value,
2812   typename basic_string<_CharT, _Traits, _Allocator>::iterator
2813>
2814basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _InputIterator __first, _InputIterator __last)
2815{
2816#if _LIBCPP_DEBUG_LEVEL == 2
2817    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2818        "string::insert(iterator, range) called with an iterator not"
2819        " referring to this string");
2820#endif
2821    const basic_string __temp(__first, __last, __alloc());
2822    return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2823}
2824
2825template <class _CharT, class _Traits, class _Allocator>
2826template<class _ForwardIterator>
2827_EnableIf
2828<
2829    __is_cpp17_forward_iterator<_ForwardIterator>::value
2830        && __libcpp_string_gets_noexcept_iterator<_ForwardIterator>::value,
2831    typename basic_string<_CharT, _Traits, _Allocator>::iterator
2832>
2833basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, _ForwardIterator __first, _ForwardIterator __last)
2834{
2835#if _LIBCPP_DEBUG_LEVEL == 2
2836    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2837        "string::insert(iterator, range) called with an iterator not"
2838        " referring to this string");
2839#endif
2840    size_type __ip = static_cast<size_type>(__pos - begin());
2841    size_type __n = static_cast<size_type>(_VSTD::distance(__first, __last));
2842    if (__n)
2843    {
2844        typedef typename iterator_traits<_ForwardIterator>::reference _CharRef;
2845        _CharRef __tmp_char = *__first;
2846        if (__ptr_in_range(_VSTD::addressof(__tmp_char), data(), data() + size()))
2847        {
2848            const basic_string __temp(__first, __last, __alloc());
2849            return insert(__pos, __temp.data(), __temp.data() + __temp.size());
2850        }
2851
2852        size_type __sz = size();
2853        size_type __cap = capacity();
2854        value_type* __p;
2855        if (__cap - __sz >= __n)
2856        {
2857            __p = _VSTD::__to_address(__get_pointer());
2858            size_type __n_move = __sz - __ip;
2859            if (__n_move != 0)
2860                traits_type::move(__p + __ip + __n, __p + __ip, __n_move);
2861        }
2862        else
2863        {
2864            __grow_by(__cap, __sz + __n - __cap, __sz, __ip, 0, __n);
2865            __p = _VSTD::__to_address(__get_long_pointer());
2866        }
2867        __sz += __n;
2868        __set_size(__sz);
2869        traits_type::assign(__p[__sz], value_type());
2870        for (__p += __ip; __first != __last; ++__p, ++__first)
2871            traits_type::assign(*__p, *__first);
2872    }
2873    return begin() + __ip;
2874}
2875
2876template <class _CharT, class _Traits, class _Allocator>
2877inline
2878basic_string<_CharT, _Traits, _Allocator>&
2879basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str)
2880{
2881    return insert(__pos1, __str.data(), __str.size());
2882}
2883
2884template <class _CharT, class _Traits, class _Allocator>
2885basic_string<_CharT, _Traits, _Allocator>&
2886basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const basic_string& __str,
2887                                                  size_type __pos2, size_type __n)
2888{
2889    size_type __str_sz = __str.size();
2890    if (__pos2 > __str_sz)
2891        this->__throw_out_of_range();
2892    return insert(__pos1, __str.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2893}
2894
2895template <class _CharT, class _Traits, class _Allocator>
2896template <class _Tp>
2897_EnableIf
2898<
2899    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value  && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
2900    basic_string<_CharT, _Traits, _Allocator>&
2901>
2902basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos1, const _Tp& __t,
2903                                                  size_type __pos2, size_type __n)
2904{
2905    __self_view __sv = __t;
2906    size_type __str_sz = __sv.size();
2907    if (__pos2 > __str_sz)
2908        this->__throw_out_of_range();
2909    return insert(__pos1, __sv.data() + __pos2, _VSTD::min(__n, __str_sz - __pos2));
2910}
2911
2912template <class _CharT, class _Traits, class _Allocator>
2913basic_string<_CharT, _Traits, _Allocator>&
2914basic_string<_CharT, _Traits, _Allocator>::insert(size_type __pos, const value_type* __s)
2915{
2916    _LIBCPP_ASSERT(__s != nullptr, "string::insert received nullptr");
2917    return insert(__pos, __s, traits_type::length(__s));
2918}
2919
2920template <class _CharT, class _Traits, class _Allocator>
2921typename basic_string<_CharT, _Traits, _Allocator>::iterator
2922basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, value_type __c)
2923{
2924    size_type __ip = static_cast<size_type>(__pos - begin());
2925    size_type __sz = size();
2926    size_type __cap = capacity();
2927    value_type* __p;
2928    if (__cap == __sz)
2929    {
2930        __grow_by(__cap, 1, __sz, __ip, 0, 1);
2931        __p = _VSTD::__to_address(__get_long_pointer());
2932    }
2933    else
2934    {
2935        __p = _VSTD::__to_address(__get_pointer());
2936        size_type __n_move = __sz - __ip;
2937        if (__n_move != 0)
2938            traits_type::move(__p + __ip + 1, __p + __ip, __n_move);
2939    }
2940    traits_type::assign(__p[__ip], __c);
2941    traits_type::assign(__p[++__sz], value_type());
2942    __set_size(__sz);
2943    return begin() + static_cast<difference_type>(__ip);
2944}
2945
2946template <class _CharT, class _Traits, class _Allocator>
2947inline
2948typename basic_string<_CharT, _Traits, _Allocator>::iterator
2949basic_string<_CharT, _Traits, _Allocator>::insert(const_iterator __pos, size_type __n, value_type __c)
2950{
2951#if _LIBCPP_DEBUG_LEVEL == 2
2952    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
2953        "string::insert(iterator, n, value) called with an iterator not"
2954        " referring to this string");
2955#endif
2956    difference_type __p = __pos - begin();
2957    insert(static_cast<size_type>(__p), __n, __c);
2958    return begin() + __p;
2959}
2960
2961// replace
2962
2963template <class _CharT, class _Traits, class _Allocator>
2964basic_string<_CharT, _Traits, _Allocator>&
2965basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s, size_type __n2)
2966    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
2967{
2968    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::replace received nullptr");
2969    size_type __sz = size();
2970    if (__pos > __sz)
2971        this->__throw_out_of_range();
2972    __n1 = _VSTD::min(__n1, __sz - __pos);
2973    size_type __cap = capacity();
2974    if (__cap - __sz + __n1 >= __n2)
2975    {
2976        value_type* __p = _VSTD::__to_address(__get_pointer());
2977        if (__n1 != __n2)
2978        {
2979            size_type __n_move = __sz - __pos - __n1;
2980            if (__n_move != 0)
2981            {
2982                if (__n1 > __n2)
2983                {
2984                    traits_type::move(__p + __pos, __s, __n2);
2985                    traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
2986                    goto __finish;
2987                }
2988                if (__p + __pos < __s && __s < __p + __sz)
2989                {
2990                    if (__p + __pos + __n1 <= __s)
2991                        __s += __n2 - __n1;
2992                    else // __p + __pos < __s < __p + __pos + __n1
2993                    {
2994                        traits_type::move(__p + __pos, __s, __n1);
2995                        __pos += __n1;
2996                        __s += __n2;
2997                        __n2 -= __n1;
2998                        __n1 = 0;
2999                    }
3000                }
3001                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
3002            }
3003        }
3004        traits_type::move(__p + __pos, __s, __n2);
3005__finish:
3006// __sz += __n2 - __n1; in this and the below function below can cause unsigned
3007// integer overflow, but this is a safe operation, so we disable the check.
3008        __sz += __n2 - __n1;
3009        __set_size(__sz);
3010        __invalidate_iterators_past(__sz);
3011        traits_type::assign(__p[__sz], value_type());
3012    }
3013    else
3014        __grow_by_and_replace(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2, __s);
3015    return *this;
3016}
3017
3018template <class _CharT, class _Traits, class _Allocator>
3019basic_string<_CharT, _Traits, _Allocator>&
3020basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, size_type __n2, value_type __c)
3021    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
3022{
3023    size_type __sz = size();
3024    if (__pos > __sz)
3025        this->__throw_out_of_range();
3026    __n1 = _VSTD::min(__n1, __sz - __pos);
3027    size_type __cap = capacity();
3028    value_type* __p;
3029    if (__cap - __sz + __n1 >= __n2)
3030    {
3031        __p = _VSTD::__to_address(__get_pointer());
3032        if (__n1 != __n2)
3033        {
3034            size_type __n_move = __sz - __pos - __n1;
3035            if (__n_move != 0)
3036                traits_type::move(__p + __pos + __n2, __p + __pos + __n1, __n_move);
3037        }
3038    }
3039    else
3040    {
3041        __grow_by(__cap, __sz - __n1 + __n2 - __cap, __sz, __pos, __n1, __n2);
3042        __p = _VSTD::__to_address(__get_long_pointer());
3043    }
3044    traits_type::assign(__p + __pos, __n2, __c);
3045    __sz += __n2 - __n1;
3046    __set_size(__sz);
3047    __invalidate_iterators_past(__sz);
3048    traits_type::assign(__p[__sz], value_type());
3049    return *this;
3050}
3051
3052template <class _CharT, class _Traits, class _Allocator>
3053template<class _InputIterator>
3054_EnableIf
3055<
3056    __is_cpp17_input_iterator<_InputIterator>::value,
3057    basic_string<_CharT, _Traits, _Allocator>&
3058>
3059basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2,
3060                                                   _InputIterator __j1, _InputIterator __j2)
3061{
3062    const basic_string __temp(__j1, __j2, __alloc());
3063    return this->replace(__i1, __i2, __temp);
3064}
3065
3066template <class _CharT, class _Traits, class _Allocator>
3067inline
3068basic_string<_CharT, _Traits, _Allocator>&
3069basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str)
3070{
3071    return replace(__pos1, __n1, __str.data(), __str.size());
3072}
3073
3074template <class _CharT, class _Traits, class _Allocator>
3075basic_string<_CharT, _Traits, _Allocator>&
3076basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const basic_string& __str,
3077                                                   size_type __pos2, size_type __n2)
3078{
3079    size_type __str_sz = __str.size();
3080    if (__pos2 > __str_sz)
3081        this->__throw_out_of_range();
3082    return replace(__pos1, __n1, __str.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
3083}
3084
3085template <class _CharT, class _Traits, class _Allocator>
3086template <class _Tp>
3087_EnableIf
3088<
3089    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
3090    basic_string<_CharT, _Traits, _Allocator>&
3091>
3092basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos1, size_type __n1, const _Tp& __t,
3093                                                   size_type __pos2, size_type __n2)
3094{
3095    __self_view __sv = __t;
3096    size_type __str_sz = __sv.size();
3097    if (__pos2 > __str_sz)
3098        this->__throw_out_of_range();
3099    return replace(__pos1, __n1, __sv.data() + __pos2, _VSTD::min(__n2, __str_sz - __pos2));
3100}
3101
3102template <class _CharT, class _Traits, class _Allocator>
3103basic_string<_CharT, _Traits, _Allocator>&
3104basic_string<_CharT, _Traits, _Allocator>::replace(size_type __pos, size_type __n1, const value_type* __s)
3105{
3106    _LIBCPP_ASSERT(__s != nullptr, "string::replace received nullptr");
3107    return replace(__pos, __n1, __s, traits_type::length(__s));
3108}
3109
3110template <class _CharT, class _Traits, class _Allocator>
3111inline
3112basic_string<_CharT, _Traits, _Allocator>&
3113basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const basic_string& __str)
3114{
3115    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1),
3116                   __str.data(), __str.size());
3117}
3118
3119template <class _CharT, class _Traits, class _Allocator>
3120inline
3121basic_string<_CharT, _Traits, _Allocator>&
3122basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s, size_type __n)
3123{
3124    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s, __n);
3125}
3126
3127template <class _CharT, class _Traits, class _Allocator>
3128inline
3129basic_string<_CharT, _Traits, _Allocator>&
3130basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, const value_type* __s)
3131{
3132    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __s);
3133}
3134
3135template <class _CharT, class _Traits, class _Allocator>
3136inline
3137basic_string<_CharT, _Traits, _Allocator>&
3138basic_string<_CharT, _Traits, _Allocator>::replace(const_iterator __i1, const_iterator __i2, size_type __n, value_type __c)
3139{
3140    return replace(static_cast<size_type>(__i1 - begin()), static_cast<size_type>(__i2 - __i1), __n, __c);
3141}
3142
3143// erase
3144
3145// 'externally instantiated' erase() implementation, called when __n != npos.
3146// Does not check __pos against size()
3147template <class _CharT, class _Traits, class _Allocator>
3148void
3149basic_string<_CharT, _Traits, _Allocator>::__erase_external_with_move(
3150    size_type __pos, size_type __n)
3151{
3152    if (__n)
3153    {
3154        size_type __sz = size();
3155        value_type* __p = _VSTD::__to_address(__get_pointer());
3156        __n = _VSTD::min(__n, __sz - __pos);
3157        size_type __n_move = __sz - __pos - __n;
3158        if (__n_move != 0)
3159            traits_type::move(__p + __pos, __p + __pos + __n, __n_move);
3160        __sz -= __n;
3161        __set_size(__sz);
3162        __invalidate_iterators_past(__sz);
3163        traits_type::assign(__p[__sz], value_type());
3164    }
3165}
3166
3167template <class _CharT, class _Traits, class _Allocator>
3168basic_string<_CharT, _Traits, _Allocator>&
3169basic_string<_CharT, _Traits, _Allocator>::erase(size_type __pos,
3170                                                 size_type __n) {
3171  if (__pos > size()) this->__throw_out_of_range();
3172  if (__n == npos) {
3173    __erase_to_end(__pos);
3174  } else {
3175    __erase_external_with_move(__pos, __n);
3176  }
3177  return *this;
3178}
3179
3180template <class _CharT, class _Traits, class _Allocator>
3181inline
3182typename basic_string<_CharT, _Traits, _Allocator>::iterator
3183basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __pos)
3184{
3185#if _LIBCPP_DEBUG_LEVEL == 2
3186    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__pos) == this,
3187        "string::erase(iterator) called with an iterator not"
3188        " referring to this string");
3189#endif
3190    _LIBCPP_ASSERT(__pos != end(),
3191        "string::erase(iterator) called with a non-dereferenceable iterator");
3192    iterator __b = begin();
3193    size_type __r = static_cast<size_type>(__pos - __b);
3194    erase(__r, 1);
3195    return __b + static_cast<difference_type>(__r);
3196}
3197
3198template <class _CharT, class _Traits, class _Allocator>
3199inline
3200typename basic_string<_CharT, _Traits, _Allocator>::iterator
3201basic_string<_CharT, _Traits, _Allocator>::erase(const_iterator __first, const_iterator __last)
3202{
3203#if _LIBCPP_DEBUG_LEVEL == 2
3204    _LIBCPP_ASSERT(__get_const_db()->__find_c_from_i(&__first) == this,
3205        "string::erase(iterator,  iterator) called with an iterator not"
3206        " referring to this string");
3207#endif
3208    _LIBCPP_ASSERT(__first <= __last, "string::erase(first, last) called with invalid range");
3209    iterator __b = begin();
3210    size_type __r = static_cast<size_type>(__first - __b);
3211    erase(__r, static_cast<size_type>(__last - __first));
3212    return __b + static_cast<difference_type>(__r);
3213}
3214
3215template <class _CharT, class _Traits, class _Allocator>
3216inline
3217void
3218basic_string<_CharT, _Traits, _Allocator>::pop_back()
3219{
3220    _LIBCPP_ASSERT(!empty(), "string::pop_back(): string is already empty");
3221    size_type __sz;
3222    if (__is_long())
3223    {
3224        __sz = __get_long_size() - 1;
3225        __set_long_size(__sz);
3226        traits_type::assign(*(__get_long_pointer() + __sz), value_type());
3227    }
3228    else
3229    {
3230        __sz = __get_short_size() - 1;
3231        __set_short_size(__sz);
3232        traits_type::assign(*(__get_short_pointer() + __sz), value_type());
3233    }
3234    __invalidate_iterators_past(__sz);
3235}
3236
3237template <class _CharT, class _Traits, class _Allocator>
3238inline
3239void
3240basic_string<_CharT, _Traits, _Allocator>::clear() _NOEXCEPT
3241{
3242    __invalidate_all_iterators();
3243    if (__is_long())
3244    {
3245        traits_type::assign(*__get_long_pointer(), value_type());
3246        __set_long_size(0);
3247    }
3248    else
3249    {
3250        traits_type::assign(*__get_short_pointer(), value_type());
3251        __set_short_size(0);
3252    }
3253}
3254
3255template <class _CharT, class _Traits, class _Allocator>
3256inline
3257void
3258basic_string<_CharT, _Traits, _Allocator>::__erase_to_end(size_type __pos)
3259{
3260    if (__is_long())
3261    {
3262        traits_type::assign(*(__get_long_pointer() + __pos), value_type());
3263        __set_long_size(__pos);
3264    }
3265    else
3266    {
3267        traits_type::assign(*(__get_short_pointer() + __pos), value_type());
3268        __set_short_size(__pos);
3269    }
3270    __invalidate_iterators_past(__pos);
3271}
3272
3273template <class _CharT, class _Traits, class _Allocator>
3274void
3275basic_string<_CharT, _Traits, _Allocator>::resize(size_type __n, value_type __c)
3276{
3277    size_type __sz = size();
3278    if (__n > __sz)
3279        append(__n - __sz, __c);
3280    else
3281        __erase_to_end(__n);
3282}
3283
3284template <class _CharT, class _Traits, class _Allocator>
3285inline void
3286basic_string<_CharT, _Traits, _Allocator>::__resize_default_init(size_type __n)
3287{
3288    size_type __sz = size();
3289    if (__n > __sz) {
3290       __append_default_init(__n - __sz);
3291    } else
3292        __erase_to_end(__n);
3293}
3294
3295template <class _CharT, class _Traits, class _Allocator>
3296inline
3297typename basic_string<_CharT, _Traits, _Allocator>::size_type
3298basic_string<_CharT, _Traits, _Allocator>::max_size() const _NOEXCEPT
3299{
3300    size_type __m = __alloc_traits::max_size(__alloc());
3301#ifdef _LIBCPP_BIG_ENDIAN
3302    return (__m <= ~__long_mask ? __m : __m/2) - __alignment;
3303#else
3304    return __m - __alignment;
3305#endif
3306}
3307
3308template <class _CharT, class _Traits, class _Allocator>
3309void
3310basic_string<_CharT, _Traits, _Allocator>::reserve(size_type __requested_capacity)
3311{
3312    if (__requested_capacity > max_size())
3313        this->__throw_length_error();
3314
3315#if _LIBCPP_STD_VER > 17
3316    // Reserve never shrinks as of C++20.
3317    if (__requested_capacity <= capacity()) return;
3318#endif
3319
3320    size_type __target_capacity = _VSTD::max(__requested_capacity, size());
3321    __target_capacity = __recommend(__target_capacity);
3322    if (__target_capacity == capacity()) return;
3323
3324    __shrink_or_extend(__target_capacity);
3325}
3326
3327template <class _CharT, class _Traits, class _Allocator>
3328void
3329basic_string<_CharT, _Traits, _Allocator>::shrink_to_fit() _NOEXCEPT
3330{
3331    size_type __target_capacity = __recommend(size());
3332    if (__target_capacity == capacity()) return;
3333
3334    __shrink_or_extend(__target_capacity);
3335}
3336
3337template <class _CharT, class _Traits, class _Allocator>
3338void
3339basic_string<_CharT, _Traits, _Allocator>::__shrink_or_extend(size_type __target_capacity)
3340{
3341    size_type __cap = capacity();
3342    size_type __sz = size();
3343
3344    pointer __new_data, __p;
3345    bool __was_long, __now_long;
3346    if (__target_capacity == __min_cap - 1)
3347    {
3348        __was_long = true;
3349        __now_long = false;
3350        __new_data = __get_short_pointer();
3351        __p = __get_long_pointer();
3352    }
3353    else
3354    {
3355        if (__target_capacity > __cap)
3356            __new_data = __alloc_traits::allocate(__alloc(), __target_capacity+1);
3357        else
3358        {
3359        #ifndef _LIBCPP_NO_EXCEPTIONS
3360            try
3361            {
3362        #endif  // _LIBCPP_NO_EXCEPTIONS
3363                __new_data = __alloc_traits::allocate(__alloc(), __target_capacity+1);
3364        #ifndef _LIBCPP_NO_EXCEPTIONS
3365            }
3366            catch (...)
3367            {
3368                return;
3369            }
3370        #else  // _LIBCPP_NO_EXCEPTIONS
3371            if (__new_data == nullptr)
3372                return;
3373        #endif  // _LIBCPP_NO_EXCEPTIONS
3374        }
3375        __now_long = true;
3376        __was_long = __is_long();
3377        __p = __get_pointer();
3378    }
3379    traits_type::copy(_VSTD::__to_address(__new_data),
3380                        _VSTD::__to_address(__p), size()+1);
3381    if (__was_long)
3382        __alloc_traits::deallocate(__alloc(), __p, __cap+1);
3383    if (__now_long)
3384    {
3385        __set_long_cap(__target_capacity+1);
3386        __set_long_size(__sz);
3387        __set_long_pointer(__new_data);
3388    }
3389    else
3390        __set_short_size(__sz);
3391    __invalidate_all_iterators();
3392}
3393
3394template <class _CharT, class _Traits, class _Allocator>
3395inline
3396typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3397basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) const _NOEXCEPT
3398{
3399    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3400    return *(data() + __pos);
3401}
3402
3403template <class _CharT, class _Traits, class _Allocator>
3404inline
3405typename basic_string<_CharT, _Traits, _Allocator>::reference
3406basic_string<_CharT, _Traits, _Allocator>::operator[](size_type __pos) _NOEXCEPT
3407{
3408    _LIBCPP_ASSERT(__pos <= size(), "string index out of bounds");
3409    return *(__get_pointer() + __pos);
3410}
3411
3412template <class _CharT, class _Traits, class _Allocator>
3413typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3414basic_string<_CharT, _Traits, _Allocator>::at(size_type __n) const
3415{
3416    if (__n >= size())
3417        this->__throw_out_of_range();
3418    return (*this)[__n];
3419}
3420
3421template <class _CharT, class _Traits, class _Allocator>
3422typename basic_string<_CharT, _Traits, _Allocator>::reference
3423basic_string<_CharT, _Traits, _Allocator>::at(size_type __n)
3424{
3425    if (__n >= size())
3426        this->__throw_out_of_range();
3427    return (*this)[__n];
3428}
3429
3430template <class _CharT, class _Traits, class _Allocator>
3431inline
3432typename basic_string<_CharT, _Traits, _Allocator>::reference
3433basic_string<_CharT, _Traits, _Allocator>::front() _NOEXCEPT
3434{
3435    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3436    return *__get_pointer();
3437}
3438
3439template <class _CharT, class _Traits, class _Allocator>
3440inline
3441typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3442basic_string<_CharT, _Traits, _Allocator>::front() const _NOEXCEPT
3443{
3444    _LIBCPP_ASSERT(!empty(), "string::front(): string is empty");
3445    return *data();
3446}
3447
3448template <class _CharT, class _Traits, class _Allocator>
3449inline
3450typename basic_string<_CharT, _Traits, _Allocator>::reference
3451basic_string<_CharT, _Traits, _Allocator>::back() _NOEXCEPT
3452{
3453    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3454    return *(__get_pointer() + size() - 1);
3455}
3456
3457template <class _CharT, class _Traits, class _Allocator>
3458inline
3459typename basic_string<_CharT, _Traits, _Allocator>::const_reference
3460basic_string<_CharT, _Traits, _Allocator>::back() const _NOEXCEPT
3461{
3462    _LIBCPP_ASSERT(!empty(), "string::back(): string is empty");
3463    return *(data() + size() - 1);
3464}
3465
3466template <class _CharT, class _Traits, class _Allocator>
3467typename basic_string<_CharT, _Traits, _Allocator>::size_type
3468basic_string<_CharT, _Traits, _Allocator>::copy(value_type* __s, size_type __n, size_type __pos) const
3469{
3470    size_type __sz = size();
3471    if (__pos > __sz)
3472        this->__throw_out_of_range();
3473    size_type __rlen = _VSTD::min(__n, __sz - __pos);
3474    traits_type::copy(__s, data() + __pos, __rlen);
3475    return __rlen;
3476}
3477
3478template <class _CharT, class _Traits, class _Allocator>
3479inline
3480basic_string<_CharT, _Traits, _Allocator>
3481basic_string<_CharT, _Traits, _Allocator>::substr(size_type __pos, size_type __n) const
3482{
3483    return basic_string(*this, __pos, __n, __alloc());
3484}
3485
3486template <class _CharT, class _Traits, class _Allocator>
3487inline
3488void
3489basic_string<_CharT, _Traits, _Allocator>::swap(basic_string& __str)
3490#if _LIBCPP_STD_VER >= 14
3491        _NOEXCEPT
3492#else
3493        _NOEXCEPT_(!__alloc_traits::propagate_on_container_swap::value ||
3494                    __is_nothrow_swappable<allocator_type>::value)
3495#endif
3496{
3497#if _LIBCPP_DEBUG_LEVEL == 2
3498    if (!__is_long())
3499        __get_db()->__invalidate_all(this);
3500    if (!__str.__is_long())
3501        __get_db()->__invalidate_all(&__str);
3502    __get_db()->swap(this, &__str);
3503#endif
3504    _LIBCPP_ASSERT(
3505        __alloc_traits::propagate_on_container_swap::value ||
3506        __alloc_traits::is_always_equal::value ||
3507        __alloc() == __str.__alloc(), "swapping non-equal allocators");
3508    _VSTD::swap(__r_.first(), __str.__r_.first());
3509    _VSTD::__swap_allocator(__alloc(), __str.__alloc());
3510}
3511
3512// find
3513
3514template <class _Traits>
3515struct _LIBCPP_HIDDEN __traits_eq
3516{
3517    typedef typename _Traits::char_type char_type;
3518    _LIBCPP_INLINE_VISIBILITY
3519    bool operator()(const char_type& __x, const char_type& __y) _NOEXCEPT
3520        {return _Traits::eq(__x, __y);}
3521};
3522
3523template<class _CharT, class _Traits, class _Allocator>
3524typename basic_string<_CharT, _Traits, _Allocator>::size_type
3525basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3526                                                size_type __pos,
3527                                                size_type __n) const _NOEXCEPT
3528{
3529    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find(): received nullptr");
3530    return __str_find<value_type, size_type, traits_type, npos>
3531        (data(), size(), __s, __pos, __n);
3532}
3533
3534template<class _CharT, class _Traits, class _Allocator>
3535inline
3536typename basic_string<_CharT, _Traits, _Allocator>::size_type
3537basic_string<_CharT, _Traits, _Allocator>::find(const basic_string& __str,
3538                                                size_type __pos) const _NOEXCEPT
3539{
3540    return __str_find<value_type, size_type, traits_type, npos>
3541        (data(), size(), __str.data(), __pos, __str.size());
3542}
3543
3544template<class _CharT, class _Traits, class _Allocator>
3545template <class _Tp>
3546_EnableIf
3547<
3548    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3549    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3550>
3551basic_string<_CharT, _Traits, _Allocator>::find(const _Tp &__t,
3552                                                size_type __pos) const _NOEXCEPT
3553{
3554    __self_view __sv = __t;
3555    return __str_find<value_type, size_type, traits_type, npos>
3556        (data(), size(), __sv.data(), __pos, __sv.size());
3557}
3558
3559template<class _CharT, class _Traits, class _Allocator>
3560inline
3561typename basic_string<_CharT, _Traits, _Allocator>::size_type
3562basic_string<_CharT, _Traits, _Allocator>::find(const value_type* __s,
3563                                                size_type __pos) const _NOEXCEPT
3564{
3565    _LIBCPP_ASSERT(__s != nullptr, "string::find(): received nullptr");
3566    return __str_find<value_type, size_type, traits_type, npos>
3567        (data(), size(), __s, __pos, traits_type::length(__s));
3568}
3569
3570template<class _CharT, class _Traits, class _Allocator>
3571typename basic_string<_CharT, _Traits, _Allocator>::size_type
3572basic_string<_CharT, _Traits, _Allocator>::find(value_type __c,
3573                                                size_type __pos) const _NOEXCEPT
3574{
3575    return __str_find<value_type, size_type, traits_type, npos>
3576        (data(), size(), __c, __pos);
3577}
3578
3579// rfind
3580
3581template<class _CharT, class _Traits, class _Allocator>
3582typename basic_string<_CharT, _Traits, _Allocator>::size_type
3583basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3584                                                 size_type __pos,
3585                                                 size_type __n) const _NOEXCEPT
3586{
3587    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::rfind(): received nullptr");
3588    return __str_rfind<value_type, size_type, traits_type, npos>
3589        (data(), size(), __s, __pos, __n);
3590}
3591
3592template<class _CharT, class _Traits, class _Allocator>
3593inline
3594typename basic_string<_CharT, _Traits, _Allocator>::size_type
3595basic_string<_CharT, _Traits, _Allocator>::rfind(const basic_string& __str,
3596                                                 size_type __pos) const _NOEXCEPT
3597{
3598    return __str_rfind<value_type, size_type, traits_type, npos>
3599        (data(), size(), __str.data(), __pos, __str.size());
3600}
3601
3602template<class _CharT, class _Traits, class _Allocator>
3603template <class _Tp>
3604_EnableIf
3605<
3606    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3607    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3608>
3609basic_string<_CharT, _Traits, _Allocator>::rfind(const _Tp& __t,
3610                                                size_type __pos) const _NOEXCEPT
3611{
3612    __self_view __sv = __t;
3613    return __str_rfind<value_type, size_type, traits_type, npos>
3614        (data(), size(), __sv.data(), __pos, __sv.size());
3615}
3616
3617template<class _CharT, class _Traits, class _Allocator>
3618inline
3619typename basic_string<_CharT, _Traits, _Allocator>::size_type
3620basic_string<_CharT, _Traits, _Allocator>::rfind(const value_type* __s,
3621                                                 size_type __pos) const _NOEXCEPT
3622{
3623    _LIBCPP_ASSERT(__s != nullptr, "string::rfind(): received nullptr");
3624    return __str_rfind<value_type, size_type, traits_type, npos>
3625        (data(), size(), __s, __pos, traits_type::length(__s));
3626}
3627
3628template<class _CharT, class _Traits, class _Allocator>
3629typename basic_string<_CharT, _Traits, _Allocator>::size_type
3630basic_string<_CharT, _Traits, _Allocator>::rfind(value_type __c,
3631                                                 size_type __pos) const _NOEXCEPT
3632{
3633    return __str_rfind<value_type, size_type, traits_type, npos>
3634        (data(), size(), __c, __pos);
3635}
3636
3637// find_first_of
3638
3639template<class _CharT, class _Traits, class _Allocator>
3640typename basic_string<_CharT, _Traits, _Allocator>::size_type
3641basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3642                                                         size_type __pos,
3643                                                         size_type __n) const _NOEXCEPT
3644{
3645    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_of(): received nullptr");
3646    return __str_find_first_of<value_type, size_type, traits_type, npos>
3647        (data(), size(), __s, __pos, __n);
3648}
3649
3650template<class _CharT, class _Traits, class _Allocator>
3651inline
3652typename basic_string<_CharT, _Traits, _Allocator>::size_type
3653basic_string<_CharT, _Traits, _Allocator>::find_first_of(const basic_string& __str,
3654                                                         size_type __pos) const _NOEXCEPT
3655{
3656    return __str_find_first_of<value_type, size_type, traits_type, npos>
3657        (data(), size(), __str.data(), __pos, __str.size());
3658}
3659
3660template<class _CharT, class _Traits, class _Allocator>
3661template <class _Tp>
3662_EnableIf
3663<
3664    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3665    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3666>
3667basic_string<_CharT, _Traits, _Allocator>::find_first_of(const _Tp& __t,
3668                                                size_type __pos) const _NOEXCEPT
3669{
3670    __self_view __sv = __t;
3671    return __str_find_first_of<value_type, size_type, traits_type, npos>
3672        (data(), size(), __sv.data(), __pos, __sv.size());
3673}
3674
3675template<class _CharT, class _Traits, class _Allocator>
3676inline
3677typename basic_string<_CharT, _Traits, _Allocator>::size_type
3678basic_string<_CharT, _Traits, _Allocator>::find_first_of(const value_type* __s,
3679                                                         size_type __pos) const _NOEXCEPT
3680{
3681    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_of(): received nullptr");
3682    return __str_find_first_of<value_type, size_type, traits_type, npos>
3683        (data(), size(), __s, __pos, traits_type::length(__s));
3684}
3685
3686template<class _CharT, class _Traits, class _Allocator>
3687inline
3688typename basic_string<_CharT, _Traits, _Allocator>::size_type
3689basic_string<_CharT, _Traits, _Allocator>::find_first_of(value_type __c,
3690                                                         size_type __pos) const _NOEXCEPT
3691{
3692    return find(__c, __pos);
3693}
3694
3695// find_last_of
3696
3697template<class _CharT, class _Traits, class _Allocator>
3698typename basic_string<_CharT, _Traits, _Allocator>::size_type
3699basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3700                                                        size_type __pos,
3701                                                        size_type __n) const _NOEXCEPT
3702{
3703    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_of(): received nullptr");
3704    return __str_find_last_of<value_type, size_type, traits_type, npos>
3705        (data(), size(), __s, __pos, __n);
3706}
3707
3708template<class _CharT, class _Traits, class _Allocator>
3709inline
3710typename basic_string<_CharT, _Traits, _Allocator>::size_type
3711basic_string<_CharT, _Traits, _Allocator>::find_last_of(const basic_string& __str,
3712                                                        size_type __pos) const _NOEXCEPT
3713{
3714    return __str_find_last_of<value_type, size_type, traits_type, npos>
3715        (data(), size(), __str.data(), __pos, __str.size());
3716}
3717
3718template<class _CharT, class _Traits, class _Allocator>
3719template <class _Tp>
3720_EnableIf
3721<
3722    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3723    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3724>
3725basic_string<_CharT, _Traits, _Allocator>::find_last_of(const _Tp& __t,
3726                                                size_type __pos) const _NOEXCEPT
3727{
3728    __self_view __sv = __t;
3729    return __str_find_last_of<value_type, size_type, traits_type, npos>
3730        (data(), size(), __sv.data(), __pos, __sv.size());
3731}
3732
3733template<class _CharT, class _Traits, class _Allocator>
3734inline
3735typename basic_string<_CharT, _Traits, _Allocator>::size_type
3736basic_string<_CharT, _Traits, _Allocator>::find_last_of(const value_type* __s,
3737                                                        size_type __pos) const _NOEXCEPT
3738{
3739    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_of(): received nullptr");
3740    return __str_find_last_of<value_type, size_type, traits_type, npos>
3741        (data(), size(), __s, __pos, traits_type::length(__s));
3742}
3743
3744template<class _CharT, class _Traits, class _Allocator>
3745inline
3746typename basic_string<_CharT, _Traits, _Allocator>::size_type
3747basic_string<_CharT, _Traits, _Allocator>::find_last_of(value_type __c,
3748                                                        size_type __pos) const _NOEXCEPT
3749{
3750    return rfind(__c, __pos);
3751}
3752
3753// find_first_not_of
3754
3755template<class _CharT, class _Traits, class _Allocator>
3756typename basic_string<_CharT, _Traits, _Allocator>::size_type
3757basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3758                                                             size_type __pos,
3759                                                             size_type __n) const _NOEXCEPT
3760{
3761    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_first_not_of(): received nullptr");
3762    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3763        (data(), size(), __s, __pos, __n);
3764}
3765
3766template<class _CharT, class _Traits, class _Allocator>
3767inline
3768typename basic_string<_CharT, _Traits, _Allocator>::size_type
3769basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const basic_string& __str,
3770                                                             size_type __pos) const _NOEXCEPT
3771{
3772    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3773        (data(), size(), __str.data(), __pos, __str.size());
3774}
3775
3776template<class _CharT, class _Traits, class _Allocator>
3777template <class _Tp>
3778_EnableIf
3779<
3780    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3781    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3782>
3783basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const _Tp& __t,
3784                                                size_type __pos) const _NOEXCEPT
3785{
3786    __self_view __sv = __t;
3787    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3788        (data(), size(), __sv.data(), __pos, __sv.size());
3789}
3790
3791template<class _CharT, class _Traits, class _Allocator>
3792inline
3793typename basic_string<_CharT, _Traits, _Allocator>::size_type
3794basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(const value_type* __s,
3795                                                             size_type __pos) const _NOEXCEPT
3796{
3797    _LIBCPP_ASSERT(__s != nullptr, "string::find_first_not_of(): received nullptr");
3798    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3799        (data(), size(), __s, __pos, traits_type::length(__s));
3800}
3801
3802template<class _CharT, class _Traits, class _Allocator>
3803inline
3804typename basic_string<_CharT, _Traits, _Allocator>::size_type
3805basic_string<_CharT, _Traits, _Allocator>::find_first_not_of(value_type __c,
3806                                                             size_type __pos) const _NOEXCEPT
3807{
3808    return __str_find_first_not_of<value_type, size_type, traits_type, npos>
3809        (data(), size(), __c, __pos);
3810}
3811
3812// find_last_not_of
3813
3814template<class _CharT, class _Traits, class _Allocator>
3815typename basic_string<_CharT, _Traits, _Allocator>::size_type
3816basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3817                                                            size_type __pos,
3818                                                            size_type __n) const _NOEXCEPT
3819{
3820    _LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string::find_last_not_of(): received nullptr");
3821    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3822        (data(), size(), __s, __pos, __n);
3823}
3824
3825template<class _CharT, class _Traits, class _Allocator>
3826inline
3827typename basic_string<_CharT, _Traits, _Allocator>::size_type
3828basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const basic_string& __str,
3829                                                            size_type __pos) const _NOEXCEPT
3830{
3831    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3832        (data(), size(), __str.data(), __pos, __str.size());
3833}
3834
3835template<class _CharT, class _Traits, class _Allocator>
3836template <class _Tp>
3837_EnableIf
3838<
3839    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3840    typename basic_string<_CharT, _Traits, _Allocator>::size_type
3841>
3842basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const _Tp& __t,
3843                                                size_type __pos) const _NOEXCEPT
3844{
3845    __self_view __sv = __t;
3846    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3847        (data(), size(), __sv.data(), __pos, __sv.size());
3848}
3849
3850template<class _CharT, class _Traits, class _Allocator>
3851inline
3852typename basic_string<_CharT, _Traits, _Allocator>::size_type
3853basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(const value_type* __s,
3854                                                            size_type __pos) const _NOEXCEPT
3855{
3856    _LIBCPP_ASSERT(__s != nullptr, "string::find_last_not_of(): received nullptr");
3857    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3858        (data(), size(), __s, __pos, traits_type::length(__s));
3859}
3860
3861template<class _CharT, class _Traits, class _Allocator>
3862inline
3863typename basic_string<_CharT, _Traits, _Allocator>::size_type
3864basic_string<_CharT, _Traits, _Allocator>::find_last_not_of(value_type __c,
3865                                                            size_type __pos) const _NOEXCEPT
3866{
3867    return __str_find_last_not_of<value_type, size_type, traits_type, npos>
3868        (data(), size(), __c, __pos);
3869}
3870
3871// compare
3872
3873template <class _CharT, class _Traits, class _Allocator>
3874template <class _Tp>
3875_EnableIf
3876<
3877    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3878    int
3879>
3880basic_string<_CharT, _Traits, _Allocator>::compare(const _Tp& __t) const _NOEXCEPT
3881{
3882    __self_view __sv = __t;
3883    size_t __lhs_sz = size();
3884    size_t __rhs_sz = __sv.size();
3885    int __result = traits_type::compare(data(), __sv.data(),
3886                                        _VSTD::min(__lhs_sz, __rhs_sz));
3887    if (__result != 0)
3888        return __result;
3889    if (__lhs_sz < __rhs_sz)
3890        return -1;
3891    if (__lhs_sz > __rhs_sz)
3892        return 1;
3893    return 0;
3894}
3895
3896template <class _CharT, class _Traits, class _Allocator>
3897inline
3898int
3899basic_string<_CharT, _Traits, _Allocator>::compare(const basic_string& __str) const _NOEXCEPT
3900{
3901    return compare(__self_view(__str));
3902}
3903
3904template <class _CharT, class _Traits, class _Allocator>
3905int
3906basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3907                                                   size_type __n1,
3908                                                   const value_type* __s,
3909                                                   size_type __n2) const
3910{
3911    _LIBCPP_ASSERT(__n2 == 0 || __s != nullptr, "string::compare(): received nullptr");
3912    size_type __sz = size();
3913    if (__pos1 > __sz || __n2 == npos)
3914        this->__throw_out_of_range();
3915    size_type __rlen = _VSTD::min(__n1, __sz - __pos1);
3916    int __r = traits_type::compare(data() + __pos1, __s, _VSTD::min(__rlen, __n2));
3917    if (__r == 0)
3918    {
3919        if (__rlen < __n2)
3920            __r = -1;
3921        else if (__rlen > __n2)
3922            __r = 1;
3923    }
3924    return __r;
3925}
3926
3927template <class _CharT, class _Traits, class _Allocator>
3928template <class _Tp>
3929_EnableIf
3930<
3931    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value,
3932    int
3933>
3934basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3935                                                   size_type __n1,
3936                                                   const _Tp& __t) const
3937{
3938    __self_view __sv = __t;
3939    return compare(__pos1, __n1, __sv.data(), __sv.size());
3940}
3941
3942template <class _CharT, class _Traits, class _Allocator>
3943inline
3944int
3945basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3946                                                   size_type __n1,
3947                                                   const basic_string& __str) const
3948{
3949    return compare(__pos1, __n1, __str.data(), __str.size());
3950}
3951
3952template <class _CharT, class _Traits, class _Allocator>
3953template <class _Tp>
3954_EnableIf
3955<
3956    __can_be_converted_to_string_view<_CharT, _Traits, _Tp>::value
3957    && !__is_same_uncvref<_Tp, basic_string<_CharT, _Traits, _Allocator> >::value,
3958    int
3959>
3960basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3961                                                   size_type __n1,
3962                                                   const _Tp& __t,
3963                                                   size_type __pos2,
3964                                                   size_type __n2) const
3965{
3966    __self_view __sv = __t;
3967    return __self_view(*this).substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
3968}
3969
3970template <class _CharT, class _Traits, class _Allocator>
3971int
3972basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3973                                                   size_type __n1,
3974                                                   const basic_string& __str,
3975                                                   size_type __pos2,
3976                                                   size_type __n2) const
3977{
3978        return compare(__pos1, __n1, __self_view(__str), __pos2, __n2);
3979}
3980
3981template <class _CharT, class _Traits, class _Allocator>
3982int
3983basic_string<_CharT, _Traits, _Allocator>::compare(const value_type* __s) const _NOEXCEPT
3984{
3985    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3986    return compare(0, npos, __s, traits_type::length(__s));
3987}
3988
3989template <class _CharT, class _Traits, class _Allocator>
3990int
3991basic_string<_CharT, _Traits, _Allocator>::compare(size_type __pos1,
3992                                                   size_type __n1,
3993                                                   const value_type* __s) const
3994{
3995    _LIBCPP_ASSERT(__s != nullptr, "string::compare(): received nullptr");
3996    return compare(__pos1, __n1, __s, traits_type::length(__s));
3997}
3998
3999// __invariants
4000
4001template<class _CharT, class _Traits, class _Allocator>
4002inline
4003bool
4004basic_string<_CharT, _Traits, _Allocator>::__invariants() const
4005{
4006    if (size() > capacity())
4007        return false;
4008    if (capacity() < __min_cap - 1)
4009        return false;
4010    if (data() == nullptr)
4011        return false;
4012    if (data()[size()] != value_type())
4013        return false;
4014    return true;
4015}
4016
4017// __clear_and_shrink
4018
4019template<class _CharT, class _Traits, class _Allocator>
4020inline
4021void
4022basic_string<_CharT, _Traits, _Allocator>::__clear_and_shrink() _NOEXCEPT
4023{
4024    clear();
4025    if(__is_long())
4026    {
4027        __alloc_traits::deallocate(__alloc(), __get_long_pointer(), capacity() + 1);
4028        __set_long_cap(0);
4029        __set_short_size(0);
4030        traits_type::assign(*__get_short_pointer(), value_type());
4031    }
4032}
4033
4034// operator==
4035
4036template<class _CharT, class _Traits, class _Allocator>
4037inline _LIBCPP_INLINE_VISIBILITY
4038bool
4039operator==(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4040           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4041{
4042    size_t __lhs_sz = __lhs.size();
4043    return __lhs_sz == __rhs.size() && _Traits::compare(__lhs.data(),
4044                                                        __rhs.data(),
4045                                                        __lhs_sz) == 0;
4046}
4047
4048template<class _Allocator>
4049inline _LIBCPP_INLINE_VISIBILITY
4050bool
4051operator==(const basic_string<char, char_traits<char>, _Allocator>& __lhs,
4052           const basic_string<char, char_traits<char>, _Allocator>& __rhs) _NOEXCEPT
4053{
4054    size_t __lhs_sz = __lhs.size();
4055    if (__lhs_sz != __rhs.size())
4056        return false;
4057    const char* __lp = __lhs.data();
4058    const char* __rp = __rhs.data();
4059    if (__lhs.__is_long())
4060        return char_traits<char>::compare(__lp, __rp, __lhs_sz) == 0;
4061    for (; __lhs_sz != 0; --__lhs_sz, ++__lp, ++__rp)
4062        if (*__lp != *__rp)
4063            return false;
4064    return true;
4065}
4066
4067template<class _CharT, class _Traits, class _Allocator>
4068inline _LIBCPP_INLINE_VISIBILITY
4069bool
4070operator==(const _CharT* __lhs,
4071           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4072{
4073    typedef basic_string<_CharT, _Traits, _Allocator> _String;
4074    _LIBCPP_ASSERT(__lhs != nullptr, "operator==(char*, basic_string): received nullptr");
4075    size_t __lhs_len = _Traits::length(__lhs);
4076    if (__lhs_len != __rhs.size()) return false;
4077    return __rhs.compare(0, _String::npos, __lhs, __lhs_len) == 0;
4078}
4079
4080template<class _CharT, class _Traits, class _Allocator>
4081inline _LIBCPP_INLINE_VISIBILITY
4082bool
4083operator==(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
4084           const _CharT* __rhs) _NOEXCEPT
4085{
4086    typedef basic_string<_CharT, _Traits, _Allocator> _String;
4087    _LIBCPP_ASSERT(__rhs != nullptr, "operator==(basic_string, char*): received nullptr");
4088    size_t __rhs_len = _Traits::length(__rhs);
4089    if (__rhs_len != __lhs.size()) return false;
4090    return __lhs.compare(0, _String::npos, __rhs, __rhs_len) == 0;
4091}
4092
4093template<class _CharT, class _Traits, class _Allocator>
4094inline _LIBCPP_INLINE_VISIBILITY
4095bool
4096operator!=(const basic_string<_CharT,_Traits,_Allocator>& __lhs,
4097           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4098{
4099    return !(__lhs == __rhs);
4100}
4101
4102template<class _CharT, class _Traits, class _Allocator>
4103inline _LIBCPP_INLINE_VISIBILITY
4104bool
4105operator!=(const _CharT* __lhs,
4106           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4107{
4108    return !(__lhs == __rhs);
4109}
4110
4111template<class _CharT, class _Traits, class _Allocator>
4112inline _LIBCPP_INLINE_VISIBILITY
4113bool
4114operator!=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4115           const _CharT* __rhs) _NOEXCEPT
4116{
4117    return !(__lhs == __rhs);
4118}
4119
4120// operator<
4121
4122template<class _CharT, class _Traits, class _Allocator>
4123inline _LIBCPP_INLINE_VISIBILITY
4124bool
4125operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4126           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4127{
4128    return __lhs.compare(__rhs) < 0;
4129}
4130
4131template<class _CharT, class _Traits, class _Allocator>
4132inline _LIBCPP_INLINE_VISIBILITY
4133bool
4134operator< (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4135           const _CharT* __rhs) _NOEXCEPT
4136{
4137    return __lhs.compare(__rhs) < 0;
4138}
4139
4140template<class _CharT, class _Traits, class _Allocator>
4141inline _LIBCPP_INLINE_VISIBILITY
4142bool
4143operator< (const _CharT* __lhs,
4144           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4145{
4146    return __rhs.compare(__lhs) > 0;
4147}
4148
4149// operator>
4150
4151template<class _CharT, class _Traits, class _Allocator>
4152inline _LIBCPP_INLINE_VISIBILITY
4153bool
4154operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4155           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4156{
4157    return __rhs < __lhs;
4158}
4159
4160template<class _CharT, class _Traits, class _Allocator>
4161inline _LIBCPP_INLINE_VISIBILITY
4162bool
4163operator> (const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4164           const _CharT* __rhs) _NOEXCEPT
4165{
4166    return __rhs < __lhs;
4167}
4168
4169template<class _CharT, class _Traits, class _Allocator>
4170inline _LIBCPP_INLINE_VISIBILITY
4171bool
4172operator> (const _CharT* __lhs,
4173           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4174{
4175    return __rhs < __lhs;
4176}
4177
4178// operator<=
4179
4180template<class _CharT, class _Traits, class _Allocator>
4181inline _LIBCPP_INLINE_VISIBILITY
4182bool
4183operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4184           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4185{
4186    return !(__rhs < __lhs);
4187}
4188
4189template<class _CharT, class _Traits, class _Allocator>
4190inline _LIBCPP_INLINE_VISIBILITY
4191bool
4192operator<=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4193           const _CharT* __rhs) _NOEXCEPT
4194{
4195    return !(__rhs < __lhs);
4196}
4197
4198template<class _CharT, class _Traits, class _Allocator>
4199inline _LIBCPP_INLINE_VISIBILITY
4200bool
4201operator<=(const _CharT* __lhs,
4202           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4203{
4204    return !(__rhs < __lhs);
4205}
4206
4207// operator>=
4208
4209template<class _CharT, class _Traits, class _Allocator>
4210inline _LIBCPP_INLINE_VISIBILITY
4211bool
4212operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4213           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4214{
4215    return !(__lhs < __rhs);
4216}
4217
4218template<class _CharT, class _Traits, class _Allocator>
4219inline _LIBCPP_INLINE_VISIBILITY
4220bool
4221operator>=(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4222           const _CharT* __rhs) _NOEXCEPT
4223{
4224    return !(__lhs < __rhs);
4225}
4226
4227template<class _CharT, class _Traits, class _Allocator>
4228inline _LIBCPP_INLINE_VISIBILITY
4229bool
4230operator>=(const _CharT* __lhs,
4231           const basic_string<_CharT, _Traits, _Allocator>& __rhs) _NOEXCEPT
4232{
4233    return !(__lhs < __rhs);
4234}
4235
4236// operator +
4237
4238template<class _CharT, class _Traits, class _Allocator>
4239basic_string<_CharT, _Traits, _Allocator>
4240operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs,
4241          const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4242{
4243    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4244    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4245    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4246    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4247    __r.append(__rhs.data(), __rhs_sz);
4248    return __r;
4249}
4250
4251template<class _CharT, class _Traits, class _Allocator>
4252basic_string<_CharT, _Traits, _Allocator>
4253operator+(const _CharT* __lhs , const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4254{
4255    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4256    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = _Traits::length(__lhs);
4257    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4258    __r.__init(__lhs, __lhs_sz, __lhs_sz + __rhs_sz);
4259    __r.append(__rhs.data(), __rhs_sz);
4260    return __r;
4261}
4262
4263template<class _CharT, class _Traits, class _Allocator>
4264basic_string<_CharT, _Traits, _Allocator>
4265operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Allocator>& __rhs)
4266{
4267    basic_string<_CharT, _Traits, _Allocator> __r(__rhs.get_allocator());
4268    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = __rhs.size();
4269    __r.__init(&__lhs, 1, 1 + __rhs_sz);
4270    __r.append(__rhs.data(), __rhs_sz);
4271    return __r;
4272}
4273
4274template<class _CharT, class _Traits, class _Allocator>
4275inline
4276basic_string<_CharT, _Traits, _Allocator>
4277operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, const _CharT* __rhs)
4278{
4279    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4280    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4281    typename basic_string<_CharT, _Traits, _Allocator>::size_type __rhs_sz = _Traits::length(__rhs);
4282    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + __rhs_sz);
4283    __r.append(__rhs, __rhs_sz);
4284    return __r;
4285}
4286
4287template<class _CharT, class _Traits, class _Allocator>
4288basic_string<_CharT, _Traits, _Allocator>
4289operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, _CharT __rhs)
4290{
4291    basic_string<_CharT, _Traits, _Allocator> __r(__lhs.get_allocator());
4292    typename basic_string<_CharT, _Traits, _Allocator>::size_type __lhs_sz = __lhs.size();
4293    __r.__init(__lhs.data(), __lhs_sz, __lhs_sz + 1);
4294    __r.push_back(__rhs);
4295    return __r;
4296}
4297
4298#ifndef _LIBCPP_CXX03_LANG
4299
4300template<class _CharT, class _Traits, class _Allocator>
4301inline _LIBCPP_INLINE_VISIBILITY
4302basic_string<_CharT, _Traits, _Allocator>
4303operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const basic_string<_CharT, _Traits, _Allocator>& __rhs)
4304{
4305    return _VSTD::move(__lhs.append(__rhs));
4306}
4307
4308template<class _CharT, class _Traits, class _Allocator>
4309inline _LIBCPP_INLINE_VISIBILITY
4310basic_string<_CharT, _Traits, _Allocator>
4311operator+(const basic_string<_CharT, _Traits, _Allocator>& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4312{
4313    return _VSTD::move(__rhs.insert(0, __lhs));
4314}
4315
4316template<class _CharT, class _Traits, class _Allocator>
4317inline _LIBCPP_INLINE_VISIBILITY
4318basic_string<_CharT, _Traits, _Allocator>
4319operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, basic_string<_CharT, _Traits, _Allocator>&& __rhs)
4320{
4321    return _VSTD::move(__lhs.append(__rhs));
4322}
4323
4324template<class _CharT, class _Traits, class _Allocator>
4325inline _LIBCPP_INLINE_VISIBILITY
4326basic_string<_CharT, _Traits, _Allocator>
4327operator+(const _CharT* __lhs , basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4328{
4329    return _VSTD::move(__rhs.insert(0, __lhs));
4330}
4331
4332template<class _CharT, class _Traits, class _Allocator>
4333inline _LIBCPP_INLINE_VISIBILITY
4334basic_string<_CharT, _Traits, _Allocator>
4335operator+(_CharT __lhs, basic_string<_CharT,_Traits,_Allocator>&& __rhs)
4336{
4337    __rhs.insert(__rhs.begin(), __lhs);
4338    return _VSTD::move(__rhs);
4339}
4340
4341template<class _CharT, class _Traits, class _Allocator>
4342inline _LIBCPP_INLINE_VISIBILITY
4343basic_string<_CharT, _Traits, _Allocator>
4344operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, const _CharT* __rhs)
4345{
4346    return _VSTD::move(__lhs.append(__rhs));
4347}
4348
4349template<class _CharT, class _Traits, class _Allocator>
4350inline _LIBCPP_INLINE_VISIBILITY
4351basic_string<_CharT, _Traits, _Allocator>
4352operator+(basic_string<_CharT, _Traits, _Allocator>&& __lhs, _CharT __rhs)
4353{
4354    __lhs.push_back(__rhs);
4355    return _VSTD::move(__lhs);
4356}
4357
4358#endif  // _LIBCPP_CXX03_LANG
4359
4360// swap
4361
4362template<class _CharT, class _Traits, class _Allocator>
4363inline _LIBCPP_INLINE_VISIBILITY
4364void
4365swap(basic_string<_CharT, _Traits, _Allocator>& __lhs,
4366     basic_string<_CharT, _Traits, _Allocator>& __rhs)
4367     _NOEXCEPT_(_NOEXCEPT_(__lhs.swap(__rhs)))
4368{
4369    __lhs.swap(__rhs);
4370}
4371
4372_LIBCPP_FUNC_VIS int                stoi  (const string& __str, size_t* __idx = nullptr, int __base = 10);
4373_LIBCPP_FUNC_VIS long               stol  (const string& __str, size_t* __idx = nullptr, int __base = 10);
4374_LIBCPP_FUNC_VIS unsigned long      stoul (const string& __str, size_t* __idx = nullptr, int __base = 10);
4375_LIBCPP_FUNC_VIS long long          stoll (const string& __str, size_t* __idx = nullptr, int __base = 10);
4376_LIBCPP_FUNC_VIS unsigned long long stoull(const string& __str, size_t* __idx = nullptr, int __base = 10);
4377
4378_LIBCPP_FUNC_VIS float       stof (const string& __str, size_t* __idx = nullptr);
4379_LIBCPP_FUNC_VIS double      stod (const string& __str, size_t* __idx = nullptr);
4380_LIBCPP_FUNC_VIS long double stold(const string& __str, size_t* __idx = nullptr);
4381
4382_LIBCPP_FUNC_VIS string to_string(int __val);
4383_LIBCPP_FUNC_VIS string to_string(unsigned __val);
4384_LIBCPP_FUNC_VIS string to_string(long __val);
4385_LIBCPP_FUNC_VIS string to_string(unsigned long __val);
4386_LIBCPP_FUNC_VIS string to_string(long long __val);
4387_LIBCPP_FUNC_VIS string to_string(unsigned long long __val);
4388_LIBCPP_FUNC_VIS string to_string(float __val);
4389_LIBCPP_FUNC_VIS string to_string(double __val);
4390_LIBCPP_FUNC_VIS string to_string(long double __val);
4391
4392_LIBCPP_FUNC_VIS int                stoi  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4393_LIBCPP_FUNC_VIS long               stol  (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4394_LIBCPP_FUNC_VIS unsigned long      stoul (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4395_LIBCPP_FUNC_VIS long long          stoll (const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4396_LIBCPP_FUNC_VIS unsigned long long stoull(const wstring& __str, size_t* __idx = nullptr, int __base = 10);
4397
4398_LIBCPP_FUNC_VIS float       stof (const wstring& __str, size_t* __idx = nullptr);
4399_LIBCPP_FUNC_VIS double      stod (const wstring& __str, size_t* __idx = nullptr);
4400_LIBCPP_FUNC_VIS long double stold(const wstring& __str, size_t* __idx = nullptr);
4401
4402_LIBCPP_FUNC_VIS wstring to_wstring(int __val);
4403_LIBCPP_FUNC_VIS wstring to_wstring(unsigned __val);
4404_LIBCPP_FUNC_VIS wstring to_wstring(long __val);
4405_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long __val);
4406_LIBCPP_FUNC_VIS wstring to_wstring(long long __val);
4407_LIBCPP_FUNC_VIS wstring to_wstring(unsigned long long __val);
4408_LIBCPP_FUNC_VIS wstring to_wstring(float __val);
4409_LIBCPP_FUNC_VIS wstring to_wstring(double __val);
4410_LIBCPP_FUNC_VIS wstring to_wstring(long double __val);
4411
4412template<class _CharT, class _Traits, class _Allocator>
4413_LIBCPP_TEMPLATE_DATA_VIS
4414const typename basic_string<_CharT, _Traits, _Allocator>::size_type
4415               basic_string<_CharT, _Traits, _Allocator>::npos;
4416
4417template <class _CharT, class _Allocator>
4418struct _LIBCPP_TEMPLATE_VIS
4419    hash<basic_string<_CharT, char_traits<_CharT>, _Allocator> >
4420    : public unary_function<
4421          basic_string<_CharT, char_traits<_CharT>, _Allocator>, size_t>
4422{
4423    size_t
4424    operator()(const basic_string<_CharT, char_traits<_CharT>, _Allocator>& __val) const _NOEXCEPT
4425    { return __do_string_hash(__val.data(), __val.data() + __val.size()); }
4426};
4427
4428
4429template<class _CharT, class _Traits, class _Allocator>
4430basic_ostream<_CharT, _Traits>&
4431operator<<(basic_ostream<_CharT, _Traits>& __os,
4432           const basic_string<_CharT, _Traits, _Allocator>& __str);
4433
4434template<class _CharT, class _Traits, class _Allocator>
4435basic_istream<_CharT, _Traits>&
4436operator>>(basic_istream<_CharT, _Traits>& __is,
4437           basic_string<_CharT, _Traits, _Allocator>& __str);
4438
4439template<class _CharT, class _Traits, class _Allocator>
4440basic_istream<_CharT, _Traits>&
4441getline(basic_istream<_CharT, _Traits>& __is,
4442        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4443
4444template<class _CharT, class _Traits, class _Allocator>
4445inline _LIBCPP_INLINE_VISIBILITY
4446basic_istream<_CharT, _Traits>&
4447getline(basic_istream<_CharT, _Traits>& __is,
4448        basic_string<_CharT, _Traits, _Allocator>& __str);
4449
4450#ifndef _LIBCPP_CXX03_LANG
4451
4452template<class _CharT, class _Traits, class _Allocator>
4453inline _LIBCPP_INLINE_VISIBILITY
4454basic_istream<_CharT, _Traits>&
4455getline(basic_istream<_CharT, _Traits>&& __is,
4456        basic_string<_CharT, _Traits, _Allocator>& __str, _CharT __dlm);
4457
4458template<class _CharT, class _Traits, class _Allocator>
4459inline _LIBCPP_INLINE_VISIBILITY
4460basic_istream<_CharT, _Traits>&
4461getline(basic_istream<_CharT, _Traits>&& __is,
4462        basic_string<_CharT, _Traits, _Allocator>& __str);
4463
4464#endif  // _LIBCPP_CXX03_LANG
4465
4466#if _LIBCPP_STD_VER > 17
4467template <class _CharT, class _Traits, class _Allocator, class _Up>
4468inline _LIBCPP_INLINE_VISIBILITY
4469    typename basic_string<_CharT, _Traits, _Allocator>::size_type
4470    erase(basic_string<_CharT, _Traits, _Allocator>& __str, const _Up& __v) {
4471  auto __old_size = __str.size();
4472  __str.erase(_VSTD::remove(__str.begin(), __str.end(), __v), __str.end());
4473  return __old_size - __str.size();
4474}
4475
4476template <class _CharT, class _Traits, class _Allocator, class _Predicate>
4477inline _LIBCPP_INLINE_VISIBILITY
4478    typename basic_string<_CharT, _Traits, _Allocator>::size_type
4479    erase_if(basic_string<_CharT, _Traits, _Allocator>& __str,
4480             _Predicate __pred) {
4481  auto __old_size = __str.size();
4482  __str.erase(_VSTD::remove_if(__str.begin(), __str.end(), __pred),
4483              __str.end());
4484  return __old_size - __str.size();
4485}
4486#endif
4487
4488#if _LIBCPP_DEBUG_LEVEL == 2
4489
4490template<class _CharT, class _Traits, class _Allocator>
4491bool
4492basic_string<_CharT, _Traits, _Allocator>::__dereferenceable(const const_iterator* __i) const
4493{
4494    return this->data() <= _VSTD::__to_address(__i->base()) &&
4495           _VSTD::__to_address(__i->base()) < this->data() + this->size();
4496}
4497
4498template<class _CharT, class _Traits, class _Allocator>
4499bool
4500basic_string<_CharT, _Traits, _Allocator>::__decrementable(const const_iterator* __i) const
4501{
4502    return this->data() < _VSTD::__to_address(__i->base()) &&
4503           _VSTD::__to_address(__i->base()) <= this->data() + this->size();
4504}
4505
4506template<class _CharT, class _Traits, class _Allocator>
4507bool
4508basic_string<_CharT, _Traits, _Allocator>::__addable(const const_iterator* __i, ptrdiff_t __n) const
4509{
4510    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4511    return this->data() <= __p && __p <= this->data() + this->size();
4512}
4513
4514template<class _CharT, class _Traits, class _Allocator>
4515bool
4516basic_string<_CharT, _Traits, _Allocator>::__subscriptable(const const_iterator* __i, ptrdiff_t __n) const
4517{
4518    const value_type* __p = _VSTD::__to_address(__i->base()) + __n;
4519    return this->data() <= __p && __p < this->data() + this->size();
4520}
4521
4522#endif  // _LIBCPP_DEBUG_LEVEL == 2
4523
4524#if _LIBCPP_STD_VER > 11
4525// Literal suffixes for basic_string [basic.string.literals]
4526inline namespace literals
4527{
4528  inline namespace string_literals
4529  {
4530    inline _LIBCPP_INLINE_VISIBILITY
4531    basic_string<char> operator "" s( const char *__str, size_t __len )
4532    {
4533        return basic_string<char> (__str, __len);
4534    }
4535
4536    inline _LIBCPP_INLINE_VISIBILITY
4537    basic_string<wchar_t> operator "" s( const wchar_t *__str, size_t __len )
4538    {
4539        return basic_string<wchar_t> (__str, __len);
4540    }
4541
4542#ifndef _LIBCPP_NO_HAS_CHAR8_T
4543    inline _LIBCPP_INLINE_VISIBILITY
4544    basic_string<char8_t> operator "" s(const char8_t *__str, size_t __len) _NOEXCEPT
4545    {
4546        return basic_string<char8_t> (__str, __len);
4547    }
4548#endif
4549
4550    inline _LIBCPP_INLINE_VISIBILITY
4551    basic_string<char16_t> operator "" s( const char16_t *__str, size_t __len )
4552    {
4553        return basic_string<char16_t> (__str, __len);
4554    }
4555
4556    inline _LIBCPP_INLINE_VISIBILITY
4557    basic_string<char32_t> operator "" s( const char32_t *__str, size_t __len )
4558    {
4559        return basic_string<char32_t> (__str, __len);
4560    }
4561  }
4562}
4563#endif
4564
4565_LIBCPP_END_NAMESPACE_STD
4566
4567_LIBCPP_POP_MACROS
4568
4569#endif  // _LIBCPP_STRING
4570