libstdc++
basic_string.h
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1 // Components for manipulating sequences of characters -*- C++ -*-
2 
3 // Copyright (C) 1997-2020 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file bits/basic_string.h
26  * This is an internal header file, included by other library headers.
27  * Do not attempt to use it directly. @headername{string}
28  */
29 
30 //
31 // ISO C++ 14882: 21 Strings library
32 //
33 
34 #ifndef _BASIC_STRING_H
35 #define _BASIC_STRING_H 1
36 
37 #pragma GCC system_header
38 
39 #include <ext/atomicity.h>
40 #include <ext/alloc_traits.h>
41 #include <debug/debug.h>
42 
43 #if __cplusplus >= 201103L
44 #include <initializer_list>
45 #endif
46 
47 #if __cplusplus >= 201703L
48 # include <string_view>
49 #endif
50 
51 
52 namespace std _GLIBCXX_VISIBILITY(default)
53 {
54 _GLIBCXX_BEGIN_NAMESPACE_VERSION
55 
56 #if _GLIBCXX_USE_CXX11_ABI
57 _GLIBCXX_BEGIN_NAMESPACE_CXX11
58  /**
59  * @class basic_string basic_string.h <string>
60  * @brief Managing sequences of characters and character-like objects.
61  *
62  * @ingroup strings
63  * @ingroup sequences
64  *
65  * @tparam _CharT Type of character
66  * @tparam _Traits Traits for character type, defaults to
67  * char_traits<_CharT>.
68  * @tparam _Alloc Allocator type, defaults to allocator<_CharT>.
69  *
70  * Meets the requirements of a <a href="tables.html#65">container</a>, a
71  * <a href="tables.html#66">reversible container</a>, and a
72  * <a href="tables.html#67">sequence</a>. Of the
73  * <a href="tables.html#68">optional sequence requirements</a>, only
74  * @c push_back, @c at, and @c %array access are supported.
75  */
76  template<typename _CharT, typename _Traits, typename _Alloc>
77  class basic_string
78  {
80  rebind<_CharT>::other _Char_alloc_type;
81  typedef __gnu_cxx::__alloc_traits<_Char_alloc_type> _Alloc_traits;
82 
83  // Types:
84  public:
85  typedef _Traits traits_type;
86  typedef typename _Traits::char_type value_type;
87  typedef _Char_alloc_type allocator_type;
88  typedef typename _Alloc_traits::size_type size_type;
89  typedef typename _Alloc_traits::difference_type difference_type;
90  typedef typename _Alloc_traits::reference reference;
91  typedef typename _Alloc_traits::const_reference const_reference;
92  typedef typename _Alloc_traits::pointer pointer;
93  typedef typename _Alloc_traits::const_pointer const_pointer;
94  typedef __gnu_cxx::__normal_iterator<pointer, basic_string> iterator;
95  typedef __gnu_cxx::__normal_iterator<const_pointer, basic_string>
96  const_iterator;
97  typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
98  typedef std::reverse_iterator<iterator> reverse_iterator;
99 
100  /// Value returned by various member functions when they fail.
101  static const size_type npos = static_cast<size_type>(-1);
102 
103  protected:
104  // type used for positions in insert, erase etc.
105 #if __cplusplus < 201103L
106  typedef iterator __const_iterator;
107 #else
108  typedef const_iterator __const_iterator;
109 #endif
110 
111  private:
112 #if __cplusplus >= 201703L
113  // A helper type for avoiding boiler-plate.
114  typedef basic_string_view<_CharT, _Traits> __sv_type;
115 
116  template<typename _Tp, typename _Res>
117  using _If_sv = enable_if_t<
118  __and_<is_convertible<const _Tp&, __sv_type>,
119  __not_<is_convertible<const _Tp*, const basic_string*>>,
120  __not_<is_convertible<const _Tp&, const _CharT*>>>::value,
121  _Res>;
122 
123  // Allows an implicit conversion to __sv_type.
124  static __sv_type
125  _S_to_string_view(__sv_type __svt) noexcept
126  { return __svt; }
127 
128  // Wraps a string_view by explicit conversion and thus
129  // allows to add an internal constructor that does not
130  // participate in overload resolution when a string_view
131  // is provided.
132  struct __sv_wrapper
133  {
134  explicit __sv_wrapper(__sv_type __sv) noexcept : _M_sv(__sv) { }
135  __sv_type _M_sv;
136  };
137 
138  /**
139  * @brief Only internally used: Construct string from a string view
140  * wrapper.
141  * @param __svw string view wrapper.
142  * @param __a Allocator to use.
143  */
144  explicit
145  basic_string(__sv_wrapper __svw, const _Alloc& __a)
146  : basic_string(__svw._M_sv.data(), __svw._M_sv.size(), __a) { }
147 #endif
148 
149  // Use empty-base optimization: http://www.cantrip.org/emptyopt.html
150  struct _Alloc_hider : allocator_type // TODO check __is_final
151  {
152 #if __cplusplus < 201103L
153  _Alloc_hider(pointer __dat, const _Alloc& __a = _Alloc())
154  : allocator_type(__a), _M_p(__dat) { }
155 #else
156  _Alloc_hider(pointer __dat, const _Alloc& __a)
157  : allocator_type(__a), _M_p(__dat) { }
158 
159  _Alloc_hider(pointer __dat, _Alloc&& __a = _Alloc())
160  : allocator_type(std::move(__a)), _M_p(__dat) { }
161 #endif
162 
163  pointer _M_p; // The actual data.
164  };
165 
166  _Alloc_hider _M_dataplus;
167  size_type _M_string_length;
168 
169  enum { _S_local_capacity = 15 / sizeof(_CharT) };
170 
171  union
172  {
173  _CharT _M_local_buf[_S_local_capacity + 1];
174  size_type _M_allocated_capacity;
175  };
176 
177  void
178  _M_data(pointer __p)
179  { _M_dataplus._M_p = __p; }
180 
181  void
182  _M_length(size_type __length)
183  { _M_string_length = __length; }
184 
185  pointer
186  _M_data() const
187  { return _M_dataplus._M_p; }
188 
189  pointer
190  _M_local_data()
191  {
192 #if __cplusplus >= 201103L
193  return std::pointer_traits<pointer>::pointer_to(*_M_local_buf);
194 #else
195  return pointer(_M_local_buf);
196 #endif
197  }
198 
199  const_pointer
200  _M_local_data() const
201  {
202 #if __cplusplus >= 201103L
204 #else
205  return const_pointer(_M_local_buf);
206 #endif
207  }
208 
209  void
210  _M_capacity(size_type __capacity)
211  { _M_allocated_capacity = __capacity; }
212 
213  void
214  _M_set_length(size_type __n)
215  {
216  _M_length(__n);
217  traits_type::assign(_M_data()[__n], _CharT());
218  }
219 
220  bool
221  _M_is_local() const
222  { return _M_data() == _M_local_data(); }
223 
224  // Create & Destroy
225  pointer
226  _M_create(size_type&, size_type);
227 
228  void
229  _M_dispose()
230  {
231  if (!_M_is_local())
232  _M_destroy(_M_allocated_capacity);
233  }
234 
235  void
236  _M_destroy(size_type __size) throw()
237  { _Alloc_traits::deallocate(_M_get_allocator(), _M_data(), __size + 1); }
238 
239  // _M_construct_aux is used to implement the 21.3.1 para 15 which
240  // requires special behaviour if _InIterator is an integral type
241  template<typename _InIterator>
242  void
243  _M_construct_aux(_InIterator __beg, _InIterator __end,
244  std::__false_type)
245  {
246  typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
247  _M_construct(__beg, __end, _Tag());
248  }
249 
250  // _GLIBCXX_RESOLVE_LIB_DEFECTS
251  // 438. Ambiguity in the "do the right thing" clause
252  template<typename _Integer>
253  void
254  _M_construct_aux(_Integer __beg, _Integer __end, std::__true_type)
255  { _M_construct_aux_2(static_cast<size_type>(__beg), __end); }
256 
257  void
258  _M_construct_aux_2(size_type __req, _CharT __c)
259  { _M_construct(__req, __c); }
260 
261  template<typename _InIterator>
262  void
263  _M_construct(_InIterator __beg, _InIterator __end)
264  {
265  typedef typename std::__is_integer<_InIterator>::__type _Integral;
266  _M_construct_aux(__beg, __end, _Integral());
267  }
268 
269  // For Input Iterators, used in istreambuf_iterators, etc.
270  template<typename _InIterator>
271  void
272  _M_construct(_InIterator __beg, _InIterator __end,
274 
275  // For forward_iterators up to random_access_iterators, used for
276  // string::iterator, _CharT*, etc.
277  template<typename _FwdIterator>
278  void
279  _M_construct(_FwdIterator __beg, _FwdIterator __end,
281 
282  void
283  _M_construct(size_type __req, _CharT __c);
284 
285  allocator_type&
286  _M_get_allocator()
287  { return _M_dataplus; }
288 
289  const allocator_type&
290  _M_get_allocator() const
291  { return _M_dataplus; }
292 
293  private:
294 
295 #ifdef _GLIBCXX_DISAMBIGUATE_REPLACE_INST
296  // The explicit instantiations in misc-inst.cc require this due to
297  // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64063
298  template<typename _Tp, bool _Requires =
299  !__are_same<_Tp, _CharT*>::__value
300  && !__are_same<_Tp, const _CharT*>::__value
301  && !__are_same<_Tp, iterator>::__value
302  && !__are_same<_Tp, const_iterator>::__value>
303  struct __enable_if_not_native_iterator
304  { typedef basic_string& __type; };
305  template<typename _Tp>
306  struct __enable_if_not_native_iterator<_Tp, false> { };
307 #endif
308 
309  size_type
310  _M_check(size_type __pos, const char* __s) const
311  {
312  if (__pos > this->size())
313  __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > "
314  "this->size() (which is %zu)"),
315  __s, __pos, this->size());
316  return __pos;
317  }
318 
319  void
320  _M_check_length(size_type __n1, size_type __n2, const char* __s) const
321  {
322  if (this->max_size() - (this->size() - __n1) < __n2)
323  __throw_length_error(__N(__s));
324  }
325 
326 
327  // NB: _M_limit doesn't check for a bad __pos value.
328  size_type
329  _M_limit(size_type __pos, size_type __off) const _GLIBCXX_NOEXCEPT
330  {
331  const bool __testoff = __off < this->size() - __pos;
332  return __testoff ? __off : this->size() - __pos;
333  }
334 
335  // True if _Rep and source do not overlap.
336  bool
337  _M_disjunct(const _CharT* __s) const _GLIBCXX_NOEXCEPT
338  {
339  return (less<const _CharT*>()(__s, _M_data())
340  || less<const _CharT*>()(_M_data() + this->size(), __s));
341  }
342 
343  // When __n = 1 way faster than the general multichar
344  // traits_type::copy/move/assign.
345  static void
346  _S_copy(_CharT* __d, const _CharT* __s, size_type __n)
347  {
348  if (__n == 1)
349  traits_type::assign(*__d, *__s);
350  else
351  traits_type::copy(__d, __s, __n);
352  }
353 
354  static void
355  _S_move(_CharT* __d, const _CharT* __s, size_type __n)
356  {
357  if (__n == 1)
358  traits_type::assign(*__d, *__s);
359  else
360  traits_type::move(__d, __s, __n);
361  }
362 
363  static void
364  _S_assign(_CharT* __d, size_type __n, _CharT __c)
365  {
366  if (__n == 1)
367  traits_type::assign(*__d, __c);
368  else
369  traits_type::assign(__d, __n, __c);
370  }
371 
372  // _S_copy_chars is a separate template to permit specialization
373  // to optimize for the common case of pointers as iterators.
374  template<class _Iterator>
375  static void
376  _S_copy_chars(_CharT* __p, _Iterator __k1, _Iterator __k2)
377  {
378  for (; __k1 != __k2; ++__k1, (void)++__p)
379  traits_type::assign(*__p, *__k1); // These types are off.
380  }
381 
382  static void
383  _S_copy_chars(_CharT* __p, iterator __k1, iterator __k2) _GLIBCXX_NOEXCEPT
384  { _S_copy_chars(__p, __k1.base(), __k2.base()); }
385 
386  static void
387  _S_copy_chars(_CharT* __p, const_iterator __k1, const_iterator __k2)
388  _GLIBCXX_NOEXCEPT
389  { _S_copy_chars(__p, __k1.base(), __k2.base()); }
390 
391  static void
392  _S_copy_chars(_CharT* __p, _CharT* __k1, _CharT* __k2) _GLIBCXX_NOEXCEPT
393  { _S_copy(__p, __k1, __k2 - __k1); }
394 
395  static void
396  _S_copy_chars(_CharT* __p, const _CharT* __k1, const _CharT* __k2)
397  _GLIBCXX_NOEXCEPT
398  { _S_copy(__p, __k1, __k2 - __k1); }
399 
400  static int
401  _S_compare(size_type __n1, size_type __n2) _GLIBCXX_NOEXCEPT
402  {
403  const difference_type __d = difference_type(__n1 - __n2);
404 
405  if (__d > __gnu_cxx::__numeric_traits<int>::__max)
406  return __gnu_cxx::__numeric_traits<int>::__max;
407  else if (__d < __gnu_cxx::__numeric_traits<int>::__min)
408  return __gnu_cxx::__numeric_traits<int>::__min;
409  else
410  return int(__d);
411  }
412 
413  void
414  _M_assign(const basic_string&);
415 
416  void
417  _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
418  size_type __len2);
419 
420  void
421  _M_erase(size_type __pos, size_type __n);
422 
423  public:
424  // Construct/copy/destroy:
425  // NB: We overload ctors in some cases instead of using default
426  // arguments, per 17.4.4.4 para. 2 item 2.
427 
428  /**
429  * @brief Default constructor creates an empty string.
430  */
431  basic_string()
432  _GLIBCXX_NOEXCEPT_IF(is_nothrow_default_constructible<_Alloc>::value)
433  : _M_dataplus(_M_local_data())
434  { _M_set_length(0); }
435 
436  /**
437  * @brief Construct an empty string using allocator @a a.
438  */
439  explicit
440  basic_string(const _Alloc& __a) _GLIBCXX_NOEXCEPT
441  : _M_dataplus(_M_local_data(), __a)
442  { _M_set_length(0); }
443 
444  /**
445  * @brief Construct string with copy of value of @a __str.
446  * @param __str Source string.
447  */
448  basic_string(const basic_string& __str)
449  : _M_dataplus(_M_local_data(),
450  _Alloc_traits::_S_select_on_copy(__str._M_get_allocator()))
451  { _M_construct(__str._M_data(), __str._M_data() + __str.length()); }
452 
453  // _GLIBCXX_RESOLVE_LIB_DEFECTS
454  // 2583. no way to supply an allocator for basic_string(str, pos)
455  /**
456  * @brief Construct string as copy of a substring.
457  * @param __str Source string.
458  * @param __pos Index of first character to copy from.
459  * @param __a Allocator to use.
460  */
461  basic_string(const basic_string& __str, size_type __pos,
462  const _Alloc& __a = _Alloc())
463  : _M_dataplus(_M_local_data(), __a)
464  {
465  const _CharT* __start = __str._M_data()
466  + __str._M_check(__pos, "basic_string::basic_string");
467  _M_construct(__start, __start + __str._M_limit(__pos, npos));
468  }
469 
470  /**
471  * @brief Construct string as copy of a substring.
472  * @param __str Source string.
473  * @param __pos Index of first character to copy from.
474  * @param __n Number of characters to copy.
475  */
476  basic_string(const basic_string& __str, size_type __pos,
477  size_type __n)
478  : _M_dataplus(_M_local_data())
479  {
480  const _CharT* __start = __str._M_data()
481  + __str._M_check(__pos, "basic_string::basic_string");
482  _M_construct(__start, __start + __str._M_limit(__pos, __n));
483  }
484 
485  /**
486  * @brief Construct string as copy of a substring.
487  * @param __str Source string.
488  * @param __pos Index of first character to copy from.
489  * @param __n Number of characters to copy.
490  * @param __a Allocator to use.
491  */
492  basic_string(const basic_string& __str, size_type __pos,
493  size_type __n, const _Alloc& __a)
494  : _M_dataplus(_M_local_data(), __a)
495  {
496  const _CharT* __start
497  = __str._M_data() + __str._M_check(__pos, "string::string");
498  _M_construct(__start, __start + __str._M_limit(__pos, __n));
499  }
500 
501  /**
502  * @brief Construct string initialized by a character %array.
503  * @param __s Source character %array.
504  * @param __n Number of characters to copy.
505  * @param __a Allocator to use (default is default allocator).
506  *
507  * NB: @a __s must have at least @a __n characters, &apos;\\0&apos;
508  * has no special meaning.
509  */
510  basic_string(const _CharT* __s, size_type __n,
511  const _Alloc& __a = _Alloc())
512  : _M_dataplus(_M_local_data(), __a)
513  { _M_construct(__s, __s + __n); }
514 
515  /**
516  * @brief Construct string as copy of a C string.
517  * @param __s Source C string.
518  * @param __a Allocator to use (default is default allocator).
519  */
520 #if __cpp_deduction_guides && ! defined _GLIBCXX_DEFINING_STRING_INSTANTIATIONS
521  // _GLIBCXX_RESOLVE_LIB_DEFECTS
522  // 3076. basic_string CTAD ambiguity
523  template<typename = _RequireAllocator<_Alloc>>
524 #endif
525  basic_string(const _CharT* __s, const _Alloc& __a = _Alloc())
526  : _M_dataplus(_M_local_data(), __a)
527  { _M_construct(__s, __s ? __s + traits_type::length(__s) : __s+npos); }
528 
529  /**
530  * @brief Construct string as multiple characters.
531  * @param __n Number of characters.
532  * @param __c Character to use.
533  * @param __a Allocator to use (default is default allocator).
534  */
535 #if __cpp_deduction_guides && ! defined _GLIBCXX_DEFINING_STRING_INSTANTIATIONS
536  // _GLIBCXX_RESOLVE_LIB_DEFECTS
537  // 3076. basic_string CTAD ambiguity
538  template<typename = _RequireAllocator<_Alloc>>
539 #endif
540  basic_string(size_type __n, _CharT __c, const _Alloc& __a = _Alloc())
541  : _M_dataplus(_M_local_data(), __a)
542  { _M_construct(__n, __c); }
543 
544 #if __cplusplus >= 201103L
545  /**
546  * @brief Move construct string.
547  * @param __str Source string.
548  *
549  * The newly-created string contains the exact contents of @a __str.
550  * @a __str is a valid, but unspecified string.
551  **/
553  : _M_dataplus(_M_local_data(), std::move(__str._M_get_allocator()))
554  {
555  if (__str._M_is_local())
556  {
557  traits_type::copy(_M_local_buf, __str._M_local_buf,
558  _S_local_capacity + 1);
559  }
560  else
561  {
562  _M_data(__str._M_data());
563  _M_capacity(__str._M_allocated_capacity);
564  }
565 
566  // Must use _M_length() here not _M_set_length() because
567  // basic_stringbuf relies on writing into unallocated capacity so
568  // we mess up the contents if we put a '\0' in the string.
569  _M_length(__str.length());
570  __str._M_data(__str._M_local_data());
571  __str._M_set_length(0);
572  }
573 
574  /**
575  * @brief Construct string from an initializer %list.
576  * @param __l std::initializer_list of characters.
577  * @param __a Allocator to use (default is default allocator).
578  */
579  basic_string(initializer_list<_CharT> __l, const _Alloc& __a = _Alloc())
580  : _M_dataplus(_M_local_data(), __a)
581  { _M_construct(__l.begin(), __l.end()); }
582 
583  basic_string(const basic_string& __str, const _Alloc& __a)
584  : _M_dataplus(_M_local_data(), __a)
585  { _M_construct(__str.begin(), __str.end()); }
586 
587  basic_string(basic_string&& __str, const _Alloc& __a)
588  noexcept(_Alloc_traits::_S_always_equal())
589  : _M_dataplus(_M_local_data(), __a)
590  {
591  if (__str._M_is_local())
592  {
593  traits_type::copy(_M_local_buf, __str._M_local_buf,
594  _S_local_capacity + 1);
595  _M_length(__str.length());
596  __str._M_set_length(0);
597  }
598  else if (_Alloc_traits::_S_always_equal()
599  || __str.get_allocator() == __a)
600  {
601  _M_data(__str._M_data());
602  _M_length(__str.length());
603  _M_capacity(__str._M_allocated_capacity);
604  __str._M_data(__str._M_local_buf);
605  __str._M_set_length(0);
606  }
607  else
608  _M_construct(__str.begin(), __str.end());
609  }
610 
611 #endif // C++11
612 
613  /**
614  * @brief Construct string as copy of a range.
615  * @param __beg Start of range.
616  * @param __end End of range.
617  * @param __a Allocator to use (default is default allocator).
618  */
619 #if __cplusplus >= 201103L
620  template<typename _InputIterator,
621  typename = std::_RequireInputIter<_InputIterator>>
622 #else
623  template<typename _InputIterator>
624 #endif
625  basic_string(_InputIterator __beg, _InputIterator __end,
626  const _Alloc& __a = _Alloc())
627  : _M_dataplus(_M_local_data(), __a)
628  { _M_construct(__beg, __end); }
629 
630 #if __cplusplus >= 201703L
631  /**
632  * @brief Construct string from a substring of a string_view.
633  * @param __t Source object convertible to string view.
634  * @param __pos The index of the first character to copy from __t.
635  * @param __n The number of characters to copy from __t.
636  * @param __a Allocator to use.
637  */
638  template<typename _Tp, typename = _If_sv<_Tp, void>>
639  basic_string(const _Tp& __t, size_type __pos, size_type __n,
640  const _Alloc& __a = _Alloc())
641  : basic_string(_S_to_string_view(__t).substr(__pos, __n), __a) { }
642 
643  /**
644  * @brief Construct string from a string_view.
645  * @param __t Source object convertible to string view.
646  * @param __a Allocator to use (default is default allocator).
647  */
648  template<typename _Tp, typename = _If_sv<_Tp, void>>
649  explicit
650  basic_string(const _Tp& __t, const _Alloc& __a = _Alloc())
651  : basic_string(__sv_wrapper(_S_to_string_view(__t)), __a) { }
652 #endif // C++17
653 
654  /**
655  * @brief Destroy the string instance.
656  */
657  ~basic_string()
658  { _M_dispose(); }
659 
660  /**
661  * @brief Assign the value of @a str to this string.
662  * @param __str Source string.
663  */
664  basic_string&
665  operator=(const basic_string& __str)
666  {
667  return this->assign(__str);
668  }
669 
670  /**
671  * @brief Copy contents of @a s into this string.
672  * @param __s Source null-terminated string.
673  */
674  basic_string&
675  operator=(const _CharT* __s)
676  { return this->assign(__s); }
677 
678  /**
679  * @brief Set value to string of length 1.
680  * @param __c Source character.
681  *
682  * Assigning to a character makes this string length 1 and
683  * (*this)[0] == @a c.
684  */
685  basic_string&
686  operator=(_CharT __c)
687  {
688  this->assign(1, __c);
689  return *this;
690  }
691 
692 #if __cplusplus >= 201103L
693  /**
694  * @brief Move assign the value of @a str to this string.
695  * @param __str Source string.
696  *
697  * The contents of @a str are moved into this string (without copying).
698  * @a str is a valid, but unspecified string.
699  **/
700  // _GLIBCXX_RESOLVE_LIB_DEFECTS
701  // 2063. Contradictory requirements for string move assignment
702  basic_string&
703  operator=(basic_string&& __str)
704  noexcept(_Alloc_traits::_S_nothrow_move())
705  {
706  if (!_M_is_local() && _Alloc_traits::_S_propagate_on_move_assign()
707  && !_Alloc_traits::_S_always_equal()
708  && _M_get_allocator() != __str._M_get_allocator())
709  {
710  // Destroy existing storage before replacing allocator.
711  _M_destroy(_M_allocated_capacity);
712  _M_data(_M_local_data());
713  _M_set_length(0);
714  }
715  // Replace allocator if POCMA is true.
716  std::__alloc_on_move(_M_get_allocator(), __str._M_get_allocator());
717 
718  if (__str._M_is_local())
719  {
720  // We've always got room for a short string, just copy it.
721  if (__str.size())
722  this->_S_copy(_M_data(), __str._M_data(), __str.size());
723  _M_set_length(__str.size());
724  }
725  else if (_Alloc_traits::_S_propagate_on_move_assign()
726  || _Alloc_traits::_S_always_equal()
727  || _M_get_allocator() == __str._M_get_allocator())
728  {
729  // Just move the allocated pointer, our allocator can free it.
730  pointer __data = nullptr;
731  size_type __capacity;
732  if (!_M_is_local())
733  {
734  if (_Alloc_traits::_S_always_equal())
735  {
736  // __str can reuse our existing storage.
737  __data = _M_data();
738  __capacity = _M_allocated_capacity;
739  }
740  else // __str can't use it, so free it.
741  _M_destroy(_M_allocated_capacity);
742  }
743 
744  _M_data(__str._M_data());
745  _M_length(__str.length());
746  _M_capacity(__str._M_allocated_capacity);
747  if (__data)
748  {
749  __str._M_data(__data);
750  __str._M_capacity(__capacity);
751  }
752  else
753  __str._M_data(__str._M_local_buf);
754  }
755  else // Need to do a deep copy
756  assign(__str);
757  __str.clear();
758  return *this;
759  }
760 
761  /**
762  * @brief Set value to string constructed from initializer %list.
763  * @param __l std::initializer_list.
764  */
765  basic_string&
766  operator=(initializer_list<_CharT> __l)
767  {
768  this->assign(__l.begin(), __l.size());
769  return *this;
770  }
771 #endif // C++11
772 
773 #if __cplusplus >= 201703L
774  /**
775  * @brief Set value to string constructed from a string_view.
776  * @param __svt An object convertible to string_view.
777  */
778  template<typename _Tp>
779  _If_sv<_Tp, basic_string&>
780  operator=(const _Tp& __svt)
781  { return this->assign(__svt); }
782 
783  /**
784  * @brief Convert to a string_view.
785  * @return A string_view.
786  */
787  operator __sv_type() const noexcept
788  { return __sv_type(data(), size()); }
789 #endif // C++17
790 
791  // Iterators:
792  /**
793  * Returns a read/write iterator that points to the first character in
794  * the %string.
795  */
796  iterator
797  begin() _GLIBCXX_NOEXCEPT
798  { return iterator(_M_data()); }
799 
800  /**
801  * Returns a read-only (constant) iterator that points to the first
802  * character in the %string.
803  */
804  const_iterator
805  begin() const _GLIBCXX_NOEXCEPT
806  { return const_iterator(_M_data()); }
807 
808  /**
809  * Returns a read/write iterator that points one past the last
810  * character in the %string.
811  */
812  iterator
813  end() _GLIBCXX_NOEXCEPT
814  { return iterator(_M_data() + this->size()); }
815 
816  /**
817  * Returns a read-only (constant) iterator that points one past the
818  * last character in the %string.
819  */
820  const_iterator
821  end() const _GLIBCXX_NOEXCEPT
822  { return const_iterator(_M_data() + this->size()); }
823 
824  /**
825  * Returns a read/write reverse iterator that points to the last
826  * character in the %string. Iteration is done in reverse element
827  * order.
828  */
829  reverse_iterator
830  rbegin() _GLIBCXX_NOEXCEPT
831  { return reverse_iterator(this->end()); }
832 
833  /**
834  * Returns a read-only (constant) reverse iterator that points
835  * to the last character in the %string. Iteration is done in
836  * reverse element order.
837  */
838  const_reverse_iterator
839  rbegin() const _GLIBCXX_NOEXCEPT
840  { return const_reverse_iterator(this->end()); }
841 
842  /**
843  * Returns a read/write reverse iterator that points to one before the
844  * first character in the %string. Iteration is done in reverse
845  * element order.
846  */
847  reverse_iterator
848  rend() _GLIBCXX_NOEXCEPT
849  { return reverse_iterator(this->begin()); }
850 
851  /**
852  * Returns a read-only (constant) reverse iterator that points
853  * to one before the first character in the %string. Iteration
854  * is done in reverse element order.
855  */
856  const_reverse_iterator
857  rend() const _GLIBCXX_NOEXCEPT
858  { return const_reverse_iterator(this->begin()); }
859 
860 #if __cplusplus >= 201103L
861  /**
862  * Returns a read-only (constant) iterator that points to the first
863  * character in the %string.
864  */
865  const_iterator
866  cbegin() const noexcept
867  { return const_iterator(this->_M_data()); }
868 
869  /**
870  * Returns a read-only (constant) iterator that points one past the
871  * last character in the %string.
872  */
873  const_iterator
874  cend() const noexcept
875  { return const_iterator(this->_M_data() + this->size()); }
876 
877  /**
878  * Returns a read-only (constant) reverse iterator that points
879  * to the last character in the %string. Iteration is done in
880  * reverse element order.
881  */
882  const_reverse_iterator
883  crbegin() const noexcept
884  { return const_reverse_iterator(this->end()); }
885 
886  /**
887  * Returns a read-only (constant) reverse iterator that points
888  * to one before the first character in the %string. Iteration
889  * is done in reverse element order.
890  */
891  const_reverse_iterator
892  crend() const noexcept
893  { return const_reverse_iterator(this->begin()); }
894 #endif
895 
896  public:
897  // Capacity:
898  /// Returns the number of characters in the string, not including any
899  /// null-termination.
900  size_type
901  size() const _GLIBCXX_NOEXCEPT
902  { return _M_string_length; }
903 
904  /// Returns the number of characters in the string, not including any
905  /// null-termination.
906  size_type
907  length() const _GLIBCXX_NOEXCEPT
908  { return _M_string_length; }
909 
910  /// Returns the size() of the largest possible %string.
911  size_type
912  max_size() const _GLIBCXX_NOEXCEPT
913  { return (_Alloc_traits::max_size(_M_get_allocator()) - 1) / 2; }
914 
915  /**
916  * @brief Resizes the %string to the specified number of characters.
917  * @param __n Number of characters the %string should contain.
918  * @param __c Character to fill any new elements.
919  *
920  * This function will %resize the %string to the specified
921  * number of characters. If the number is smaller than the
922  * %string's current size the %string is truncated, otherwise
923  * the %string is extended and new elements are %set to @a __c.
924  */
925  void
926  resize(size_type __n, _CharT __c);
927 
928  /**
929  * @brief Resizes the %string to the specified number of characters.
930  * @param __n Number of characters the %string should contain.
931  *
932  * This function will resize the %string to the specified length. If
933  * the new size is smaller than the %string's current size the %string
934  * is truncated, otherwise the %string is extended and new characters
935  * are default-constructed. For basic types such as char, this means
936  * setting them to 0.
937  */
938  void
939  resize(size_type __n)
940  { this->resize(__n, _CharT()); }
941 
942 #if __cplusplus >= 201103L
943  /// A non-binding request to reduce capacity() to size().
944  void
946  {
947 #if __cpp_exceptions
948  if (capacity() > size())
949  {
950  try
951  { reserve(0); }
952  catch(...)
953  { }
954  }
955 #endif
956  }
957 #endif
958 
959  /**
960  * Returns the total number of characters that the %string can hold
961  * before needing to allocate more memory.
962  */
963  size_type
964  capacity() const _GLIBCXX_NOEXCEPT
965  {
966  return _M_is_local() ? size_type(_S_local_capacity)
967  : _M_allocated_capacity;
968  }
969 
970  /**
971  * @brief Attempt to preallocate enough memory for specified number of
972  * characters.
973  * @param __res_arg Number of characters required.
974  * @throw std::length_error If @a __res_arg exceeds @c max_size().
975  *
976  * This function attempts to reserve enough memory for the
977  * %string to hold the specified number of characters. If the
978  * number requested is more than max_size(), length_error is
979  * thrown.
980  *
981  * The advantage of this function is that if optimal code is a
982  * necessity and the user can determine the string length that will be
983  * required, the user can reserve the memory in %advance, and thus
984  * prevent a possible reallocation of memory and copying of %string
985  * data.
986  */
987  void
988  reserve(size_type __res_arg = 0);
989 
990  /**
991  * Erases the string, making it empty.
992  */
993  void
994  clear() _GLIBCXX_NOEXCEPT
995  { _M_set_length(0); }
996 
997  /**
998  * Returns true if the %string is empty. Equivalent to
999  * <code>*this == ""</code>.
1000  */
1001  _GLIBCXX_NODISCARD bool
1002  empty() const _GLIBCXX_NOEXCEPT
1003  { return this->size() == 0; }
1004 
1005  // Element access:
1006  /**
1007  * @brief Subscript access to the data contained in the %string.
1008  * @param __pos The index of the character to access.
1009  * @return Read-only (constant) reference to the character.
1010  *
1011  * This operator allows for easy, array-style, data access.
1012  * Note that data access with this operator is unchecked and
1013  * out_of_range lookups are not defined. (For checked lookups
1014  * see at().)
1015  */
1016  const_reference
1017  operator[] (size_type __pos) const _GLIBCXX_NOEXCEPT
1018  {
1019  __glibcxx_assert(__pos <= size());
1020  return _M_data()[__pos];
1021  }
1022 
1023  /**
1024  * @brief Subscript access to the data contained in the %string.
1025  * @param __pos The index of the character to access.
1026  * @return Read/write reference to the character.
1027  *
1028  * This operator allows for easy, array-style, data access.
1029  * Note that data access with this operator is unchecked and
1030  * out_of_range lookups are not defined. (For checked lookups
1031  * see at().)
1032  */
1033  reference
1034  operator[](size_type __pos)
1035  {
1036  // Allow pos == size() both in C++98 mode, as v3 extension,
1037  // and in C++11 mode.
1038  __glibcxx_assert(__pos <= size());
1039  // In pedantic mode be strict in C++98 mode.
1040  _GLIBCXX_DEBUG_PEDASSERT(__cplusplus >= 201103L || __pos < size());
1041  return _M_data()[__pos];
1042  }
1043 
1044  /**
1045  * @brief Provides access to the data contained in the %string.
1046  * @param __n The index of the character to access.
1047  * @return Read-only (const) reference to the character.
1048  * @throw std::out_of_range If @a n is an invalid index.
1049  *
1050  * This function provides for safer data access. The parameter is
1051  * first checked that it is in the range of the string. The function
1052  * throws out_of_range if the check fails.
1053  */
1054  const_reference
1055  at(size_type __n) const
1056  {
1057  if (__n >= this->size())
1058  __throw_out_of_range_fmt(__N("basic_string::at: __n "
1059  "(which is %zu) >= this->size() "
1060  "(which is %zu)"),
1061  __n, this->size());
1062  return _M_data()[__n];
1063  }
1064 
1065  /**
1066  * @brief Provides access to the data contained in the %string.
1067  * @param __n The index of the character to access.
1068  * @return Read/write reference to the character.
1069  * @throw std::out_of_range If @a n is an invalid index.
1070  *
1071  * This function provides for safer data access. The parameter is
1072  * first checked that it is in the range of the string. The function
1073  * throws out_of_range if the check fails.
1074  */
1075  reference
1076  at(size_type __n)
1077  {
1078  if (__n >= size())
1079  __throw_out_of_range_fmt(__N("basic_string::at: __n "
1080  "(which is %zu) >= this->size() "
1081  "(which is %zu)"),
1082  __n, this->size());
1083  return _M_data()[__n];
1084  }
1085 
1086 #if __cplusplus >= 201103L
1087  /**
1088  * Returns a read/write reference to the data at the first
1089  * element of the %string.
1090  */
1091  reference
1092  front() noexcept
1093  {
1094  __glibcxx_assert(!empty());
1095  return operator[](0);
1096  }
1097 
1098  /**
1099  * Returns a read-only (constant) reference to the data at the first
1100  * element of the %string.
1101  */
1102  const_reference
1103  front() const noexcept
1104  {
1105  __glibcxx_assert(!empty());
1106  return operator[](0);
1107  }
1108 
1109  /**
1110  * Returns a read/write reference to the data at the last
1111  * element of the %string.
1112  */
1113  reference
1114  back() noexcept
1115  {
1116  __glibcxx_assert(!empty());
1117  return operator[](this->size() - 1);
1118  }
1119 
1120  /**
1121  * Returns a read-only (constant) reference to the data at the
1122  * last element of the %string.
1123  */
1124  const_reference
1125  back() const noexcept
1126  {
1127  __glibcxx_assert(!empty());
1128  return operator[](this->size() - 1);
1129  }
1130 #endif
1131 
1132  // Modifiers:
1133  /**
1134  * @brief Append a string to this string.
1135  * @param __str The string to append.
1136  * @return Reference to this string.
1137  */
1138  basic_string&
1139  operator+=(const basic_string& __str)
1140  { return this->append(__str); }
1141 
1142  /**
1143  * @brief Append a C string.
1144  * @param __s The C string to append.
1145  * @return Reference to this string.
1146  */
1147  basic_string&
1148  operator+=(const _CharT* __s)
1149  { return this->append(__s); }
1150 
1151  /**
1152  * @brief Append a character.
1153  * @param __c The character to append.
1154  * @return Reference to this string.
1155  */
1156  basic_string&
1157  operator+=(_CharT __c)
1158  {
1159  this->push_back(__c);
1160  return *this;
1161  }
1162 
1163 #if __cplusplus >= 201103L
1164  /**
1165  * @brief Append an initializer_list of characters.
1166  * @param __l The initializer_list of characters to be appended.
1167  * @return Reference to this string.
1168  */
1169  basic_string&
1170  operator+=(initializer_list<_CharT> __l)
1171  { return this->append(__l.begin(), __l.size()); }
1172 #endif // C++11
1173 
1174 #if __cplusplus >= 201703L
1175  /**
1176  * @brief Append a string_view.
1177  * @param __svt An object convertible to string_view to be appended.
1178  * @return Reference to this string.
1179  */
1180  template<typename _Tp>
1181  _If_sv<_Tp, basic_string&>
1182  operator+=(const _Tp& __svt)
1183  { return this->append(__svt); }
1184 #endif // C++17
1185 
1186  /**
1187  * @brief Append a string to this string.
1188  * @param __str The string to append.
1189  * @return Reference to this string.
1190  */
1191  basic_string&
1192  append(const basic_string& __str)
1193  { return _M_append(__str._M_data(), __str.size()); }
1194 
1195  /**
1196  * @brief Append a substring.
1197  * @param __str The string to append.
1198  * @param __pos Index of the first character of str to append.
1199  * @param __n The number of characters to append.
1200  * @return Reference to this string.
1201  * @throw std::out_of_range if @a __pos is not a valid index.
1202  *
1203  * This function appends @a __n characters from @a __str
1204  * starting at @a __pos to this string. If @a __n is is larger
1205  * than the number of available characters in @a __str, the
1206  * remainder of @a __str is appended.
1207  */
1208  basic_string&
1209  append(const basic_string& __str, size_type __pos, size_type __n = npos)
1210  { return _M_append(__str._M_data()
1211  + __str._M_check(__pos, "basic_string::append"),
1212  __str._M_limit(__pos, __n)); }
1213 
1214  /**
1215  * @brief Append a C substring.
1216  * @param __s The C string to append.
1217  * @param __n The number of characters to append.
1218  * @return Reference to this string.
1219  */
1220  basic_string&
1221  append(const _CharT* __s, size_type __n)
1222  {
1223  __glibcxx_requires_string_len(__s, __n);
1224  _M_check_length(size_type(0), __n, "basic_string::append");
1225  return _M_append(__s, __n);
1226  }
1227 
1228  /**
1229  * @brief Append a C string.
1230  * @param __s The C string to append.
1231  * @return Reference to this string.
1232  */
1233  basic_string&
1234  append(const _CharT* __s)
1235  {
1236  __glibcxx_requires_string(__s);
1237  const size_type __n = traits_type::length(__s);
1238  _M_check_length(size_type(0), __n, "basic_string::append");
1239  return _M_append(__s, __n);
1240  }
1241 
1242  /**
1243  * @brief Append multiple characters.
1244  * @param __n The number of characters to append.
1245  * @param __c The character to use.
1246  * @return Reference to this string.
1247  *
1248  * Appends __n copies of __c to this string.
1249  */
1250  basic_string&
1251  append(size_type __n, _CharT __c)
1252  { return _M_replace_aux(this->size(), size_type(0), __n, __c); }
1253 
1254 #if __cplusplus >= 201103L
1255  /**
1256  * @brief Append an initializer_list of characters.
1257  * @param __l The initializer_list of characters to append.
1258  * @return Reference to this string.
1259  */
1260  basic_string&
1261  append(initializer_list<_CharT> __l)
1262  { return this->append(__l.begin(), __l.size()); }
1263 #endif // C++11
1264 
1265  /**
1266  * @brief Append a range of characters.
1267  * @param __first Iterator referencing the first character to append.
1268  * @param __last Iterator marking the end of the range.
1269  * @return Reference to this string.
1270  *
1271  * Appends characters in the range [__first,__last) to this string.
1272  */
1273 #if __cplusplus >= 201103L
1274  template<class _InputIterator,
1275  typename = std::_RequireInputIter<_InputIterator>>
1276 #else
1277  template<class _InputIterator>
1278 #endif
1279  basic_string&
1280  append(_InputIterator __first, _InputIterator __last)
1281  { return this->replace(end(), end(), __first, __last); }
1282 
1283 #if __cplusplus >= 201703L
1284  /**
1285  * @brief Append a string_view.
1286  * @param __svt An object convertible to string_view to be appended.
1287  * @return Reference to this string.
1288  */
1289  template<typename _Tp>
1290  _If_sv<_Tp, basic_string&>
1291  append(const _Tp& __svt)
1292  {
1293  __sv_type __sv = __svt;
1294  return this->append(__sv.data(), __sv.size());
1295  }
1296 
1297  /**
1298  * @brief Append a range of characters from a string_view.
1299  * @param __svt An object convertible to string_view to be appended from.
1300  * @param __pos The position in the string_view to append from.
1301  * @param __n The number of characters to append from the string_view.
1302  * @return Reference to this string.
1303  */
1304  template<typename _Tp>
1305  _If_sv<_Tp, basic_string&>
1306  append(const _Tp& __svt, size_type __pos, size_type __n = npos)
1307  {
1308  __sv_type __sv = __svt;
1309  return _M_append(__sv.data()
1310  + std::__sv_check(__sv.size(), __pos, "basic_string::append"),
1311  std::__sv_limit(__sv.size(), __pos, __n));
1312  }
1313 #endif // C++17
1314 
1315  /**
1316  * @brief Append a single character.
1317  * @param __c Character to append.
1318  */
1319  void
1320  push_back(_CharT __c)
1321  {
1322  const size_type __size = this->size();
1323  if (__size + 1 > this->capacity())
1324  this->_M_mutate(__size, size_type(0), 0, size_type(1));
1325  traits_type::assign(this->_M_data()[__size], __c);
1326  this->_M_set_length(__size + 1);
1327  }
1328 
1329  /**
1330  * @brief Set value to contents of another string.
1331  * @param __str Source string to use.
1332  * @return Reference to this string.
1333  */
1334  basic_string&
1335  assign(const basic_string& __str)
1336  {
1337 #if __cplusplus >= 201103L
1338  if (_Alloc_traits::_S_propagate_on_copy_assign())
1339  {
1340  if (!_Alloc_traits::_S_always_equal() && !_M_is_local()
1341  && _M_get_allocator() != __str._M_get_allocator())
1342  {
1343  // Propagating allocator cannot free existing storage so must
1344  // deallocate it before replacing current allocator.
1345  if (__str.size() <= _S_local_capacity)
1346  {
1347  _M_destroy(_M_allocated_capacity);
1348  _M_data(_M_local_data());
1349  _M_set_length(0);
1350  }
1351  else
1352  {
1353  const auto __len = __str.size();
1354  auto __alloc = __str._M_get_allocator();
1355  // If this allocation throws there are no effects:
1356  auto __ptr = _Alloc_traits::allocate(__alloc, __len + 1);
1357  _M_destroy(_M_allocated_capacity);
1358  _M_data(__ptr);
1359  _M_capacity(__len);
1360  _M_set_length(__len);
1361  }
1362  }
1363  std::__alloc_on_copy(_M_get_allocator(), __str._M_get_allocator());
1364  }
1365 #endif
1366  this->_M_assign(__str);
1367  return *this;
1368  }
1369 
1370 #if __cplusplus >= 201103L
1371  /**
1372  * @brief Set value to contents of another string.
1373  * @param __str Source string to use.
1374  * @return Reference to this string.
1375  *
1376  * This function sets this string to the exact contents of @a __str.
1377  * @a __str is a valid, but unspecified string.
1378  */
1379  basic_string&
1380  assign(basic_string&& __str)
1381  noexcept(_Alloc_traits::_S_nothrow_move())
1382  {
1383  // _GLIBCXX_RESOLVE_LIB_DEFECTS
1384  // 2063. Contradictory requirements for string move assignment
1385  return *this = std::move(__str);
1386  }
1387 #endif // C++11
1388 
1389  /**
1390  * @brief Set value to a substring of a string.
1391  * @param __str The string to use.
1392  * @param __pos Index of the first character of str.
1393  * @param __n Number of characters to use.
1394  * @return Reference to this string.
1395  * @throw std::out_of_range if @a pos is not a valid index.
1396  *
1397  * This function sets this string to the substring of @a __str
1398  * consisting of @a __n characters at @a __pos. If @a __n is
1399  * is larger than the number of available characters in @a
1400  * __str, the remainder of @a __str is used.
1401  */
1402  basic_string&
1403  assign(const basic_string& __str, size_type __pos, size_type __n = npos)
1404  { return _M_replace(size_type(0), this->size(), __str._M_data()
1405  + __str._M_check(__pos, "basic_string::assign"),
1406  __str._M_limit(__pos, __n)); }
1407 
1408  /**
1409  * @brief Set value to a C substring.
1410  * @param __s The C string to use.
1411  * @param __n Number of characters to use.
1412  * @return Reference to this string.
1413  *
1414  * This function sets the value of this string to the first @a __n
1415  * characters of @a __s. If @a __n is is larger than the number of
1416  * available characters in @a __s, the remainder of @a __s is used.
1417  */
1418  basic_string&
1419  assign(const _CharT* __s, size_type __n)
1420  {
1421  __glibcxx_requires_string_len(__s, __n);
1422  return _M_replace(size_type(0), this->size(), __s, __n);
1423  }
1424 
1425  /**
1426  * @brief Set value to contents of a C string.
1427  * @param __s The C string to use.
1428  * @return Reference to this string.
1429  *
1430  * This function sets the value of this string to the value of @a __s.
1431  * The data is copied, so there is no dependence on @a __s once the
1432  * function returns.
1433  */
1434  basic_string&
1435  assign(const _CharT* __s)
1436  {
1437  __glibcxx_requires_string(__s);
1438  return _M_replace(size_type(0), this->size(), __s,
1439  traits_type::length(__s));
1440  }
1441 
1442  /**
1443  * @brief Set value to multiple characters.
1444  * @param __n Length of the resulting string.
1445  * @param __c The character to use.
1446  * @return Reference to this string.
1447  *
1448  * This function sets the value of this string to @a __n copies of
1449  * character @a __c.
1450  */
1451  basic_string&
1452  assign(size_type __n, _CharT __c)
1453  { return _M_replace_aux(size_type(0), this->size(), __n, __c); }
1454 
1455  /**
1456  * @brief Set value to a range of characters.
1457  * @param __first Iterator referencing the first character to append.
1458  * @param __last Iterator marking the end of the range.
1459  * @return Reference to this string.
1460  *
1461  * Sets value of string to characters in the range [__first,__last).
1462  */
1463 #if __cplusplus >= 201103L
1464  template<class _InputIterator,
1465  typename = std::_RequireInputIter<_InputIterator>>
1466 #else
1467  template<class _InputIterator>
1468 #endif
1469  basic_string&
1470  assign(_InputIterator __first, _InputIterator __last)
1471  { return this->replace(begin(), end(), __first, __last); }
1472 
1473 #if __cplusplus >= 201103L
1474  /**
1475  * @brief Set value to an initializer_list of characters.
1476  * @param __l The initializer_list of characters to assign.
1477  * @return Reference to this string.
1478  */
1479  basic_string&
1480  assign(initializer_list<_CharT> __l)
1481  { return this->assign(__l.begin(), __l.size()); }
1482 #endif // C++11
1483 
1484 #if __cplusplus >= 201703L
1485  /**
1486  * @brief Set value from a string_view.
1487  * @param __svt The source object convertible to string_view.
1488  * @return Reference to this string.
1489  */
1490  template<typename _Tp>
1491  _If_sv<_Tp, basic_string&>
1492  assign(const _Tp& __svt)
1493  {
1494  __sv_type __sv = __svt;
1495  return this->assign(__sv.data(), __sv.size());
1496  }
1497 
1498  /**
1499  * @brief Set value from a range of characters in a string_view.
1500  * @param __svt The source object convertible to string_view.
1501  * @param __pos The position in the string_view to assign from.
1502  * @param __n The number of characters to assign.
1503  * @return Reference to this string.
1504  */
1505  template<typename _Tp>
1506  _If_sv<_Tp, basic_string&>
1507  assign(const _Tp& __svt, size_type __pos, size_type __n = npos)
1508  {
1509  __sv_type __sv = __svt;
1510  return _M_replace(size_type(0), this->size(),
1511  __sv.data()
1512  + std::__sv_check(__sv.size(), __pos, "basic_string::assign"),
1513  std::__sv_limit(__sv.size(), __pos, __n));
1514  }
1515 #endif // C++17
1516 
1517 #if __cplusplus >= 201103L
1518  /**
1519  * @brief Insert multiple characters.
1520  * @param __p Const_iterator referencing location in string to
1521  * insert at.
1522  * @param __n Number of characters to insert
1523  * @param __c The character to insert.
1524  * @return Iterator referencing the first inserted char.
1525  * @throw std::length_error If new length exceeds @c max_size().
1526  *
1527  * Inserts @a __n copies of character @a __c starting at the
1528  * position referenced by iterator @a __p. If adding
1529  * characters causes the length to exceed max_size(),
1530  * length_error is thrown. The value of the string doesn't
1531  * change if an error is thrown.
1532  */
1533  iterator
1534  insert(const_iterator __p, size_type __n, _CharT __c)
1535  {
1536  _GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1537  const size_type __pos = __p - begin();
1538  this->replace(__p, __p, __n, __c);
1539  return iterator(this->_M_data() + __pos);
1540  }
1541 #else
1542  /**
1543  * @brief Insert multiple characters.
1544  * @param __p Iterator referencing location in string to insert at.
1545  * @param __n Number of characters to insert
1546  * @param __c The character to insert.
1547  * @throw std::length_error If new length exceeds @c max_size().
1548  *
1549  * Inserts @a __n copies of character @a __c starting at the
1550  * position referenced by iterator @a __p. If adding
1551  * characters causes the length to exceed max_size(),
1552  * length_error is thrown. The value of the string doesn't
1553  * change if an error is thrown.
1554  */
1555  void
1556  insert(iterator __p, size_type __n, _CharT __c)
1557  { this->replace(__p, __p, __n, __c); }
1558 #endif
1559 
1560 #if __cplusplus >= 201103L
1561  /**
1562  * @brief Insert a range of characters.
1563  * @param __p Const_iterator referencing location in string to
1564  * insert at.
1565  * @param __beg Start of range.
1566  * @param __end End of range.
1567  * @return Iterator referencing the first inserted char.
1568  * @throw std::length_error If new length exceeds @c max_size().
1569  *
1570  * Inserts characters in range [beg,end). If adding characters
1571  * causes the length to exceed max_size(), length_error is
1572  * thrown. The value of the string doesn't change if an error
1573  * is thrown.
1574  */
1575  template<class _InputIterator,
1576  typename = std::_RequireInputIter<_InputIterator>>
1577  iterator
1578  insert(const_iterator __p, _InputIterator __beg, _InputIterator __end)
1579  {
1580  _GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1581  const size_type __pos = __p - begin();
1582  this->replace(__p, __p, __beg, __end);
1583  return iterator(this->_M_data() + __pos);
1584  }
1585 #else
1586  /**
1587  * @brief Insert a range of characters.
1588  * @param __p Iterator referencing location in string to insert at.
1589  * @param __beg Start of range.
1590  * @param __end End of range.
1591  * @throw std::length_error If new length exceeds @c max_size().
1592  *
1593  * Inserts characters in range [__beg,__end). If adding
1594  * characters causes the length to exceed max_size(),
1595  * length_error is thrown. The value of the string doesn't
1596  * change if an error is thrown.
1597  */
1598  template<class _InputIterator>
1599  void
1600  insert(iterator __p, _InputIterator __beg, _InputIterator __end)
1601  { this->replace(__p, __p, __beg, __end); }
1602 #endif
1603 
1604 #if __cplusplus >= 201103L
1605  /**
1606  * @brief Insert an initializer_list of characters.
1607  * @param __p Iterator referencing location in string to insert at.
1608  * @param __l The initializer_list of characters to insert.
1609  * @throw std::length_error If new length exceeds @c max_size().
1610  */
1611  iterator
1612  insert(const_iterator __p, initializer_list<_CharT> __l)
1613  { return this->insert(__p, __l.begin(), __l.end()); }
1614 
1615 #ifdef _GLIBCXX_DEFINING_STRING_INSTANTIATIONS
1616  // See PR libstdc++/83328
1617  void
1618  insert(iterator __p, initializer_list<_CharT> __l)
1619  {
1620  _GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1621  this->insert(__p - begin(), __l.begin(), __l.size());
1622  }
1623 #endif
1624 #endif // C++11
1625 
1626  /**
1627  * @brief Insert value of a string.
1628  * @param __pos1 Position in string to insert at.
1629  * @param __str The string to insert.
1630  * @return Reference to this string.
1631  * @throw std::length_error If new length exceeds @c max_size().
1632  *
1633  * Inserts value of @a __str starting at @a __pos1. If adding
1634  * characters causes the length to exceed max_size(),
1635  * length_error is thrown. The value of the string doesn't
1636  * change if an error is thrown.
1637  */
1638  basic_string&
1639  insert(size_type __pos1, const basic_string& __str)
1640  { return this->replace(__pos1, size_type(0),
1641  __str._M_data(), __str.size()); }
1642 
1643  /**
1644  * @brief Insert a substring.
1645  * @param __pos1 Position in string to insert at.
1646  * @param __str The string to insert.
1647  * @param __pos2 Start of characters in str to insert.
1648  * @param __n Number of characters to insert.
1649  * @return Reference to this string.
1650  * @throw std::length_error If new length exceeds @c max_size().
1651  * @throw std::out_of_range If @a pos1 > size() or
1652  * @a __pos2 > @a str.size().
1653  *
1654  * Starting at @a pos1, insert @a __n character of @a __str
1655  * beginning with @a __pos2. If adding characters causes the
1656  * length to exceed max_size(), length_error is thrown. If @a
1657  * __pos1 is beyond the end of this string or @a __pos2 is
1658  * beyond the end of @a __str, out_of_range is thrown. The
1659  * value of the string doesn't change if an error is thrown.
1660  */
1661  basic_string&
1662  insert(size_type __pos1, const basic_string& __str,
1663  size_type __pos2, size_type __n = npos)
1664  { return this->replace(__pos1, size_type(0), __str._M_data()
1665  + __str._M_check(__pos2, "basic_string::insert"),
1666  __str._M_limit(__pos2, __n)); }
1667 
1668  /**
1669  * @brief Insert a C substring.
1670  * @param __pos Position in string to insert at.
1671  * @param __s The C string to insert.
1672  * @param __n The number of characters to insert.
1673  * @return Reference to this string.
1674  * @throw std::length_error If new length exceeds @c max_size().
1675  * @throw std::out_of_range If @a __pos is beyond the end of this
1676  * string.
1677  *
1678  * Inserts the first @a __n characters of @a __s starting at @a
1679  * __pos. If adding characters causes the length to exceed
1680  * max_size(), length_error is thrown. If @a __pos is beyond
1681  * end(), out_of_range is thrown. The value of the string
1682  * doesn't change if an error is thrown.
1683  */
1684  basic_string&
1685  insert(size_type __pos, const _CharT* __s, size_type __n)
1686  { return this->replace(__pos, size_type(0), __s, __n); }
1687 
1688  /**
1689  * @brief Insert a C string.
1690  * @param __pos Position in string to insert at.
1691  * @param __s The C string to insert.
1692  * @return Reference to this string.
1693  * @throw std::length_error If new length exceeds @c max_size().
1694  * @throw std::out_of_range If @a pos is beyond the end of this
1695  * string.
1696  *
1697  * Inserts the first @a n characters of @a __s starting at @a __pos. If
1698  * adding characters causes the length to exceed max_size(),
1699  * length_error is thrown. If @a __pos is beyond end(), out_of_range is
1700  * thrown. The value of the string doesn't change if an error is
1701  * thrown.
1702  */
1703  basic_string&
1704  insert(size_type __pos, const _CharT* __s)
1705  {
1706  __glibcxx_requires_string(__s);
1707  return this->replace(__pos, size_type(0), __s,
1708  traits_type::length(__s));
1709  }
1710 
1711  /**
1712  * @brief Insert multiple characters.
1713  * @param __pos Index in string to insert at.
1714  * @param __n Number of characters to insert
1715  * @param __c The character to insert.
1716  * @return Reference to this string.
1717  * @throw std::length_error If new length exceeds @c max_size().
1718  * @throw std::out_of_range If @a __pos is beyond the end of this
1719  * string.
1720  *
1721  * Inserts @a __n copies of character @a __c starting at index
1722  * @a __pos. If adding characters causes the length to exceed
1723  * max_size(), length_error is thrown. If @a __pos > length(),
1724  * out_of_range is thrown. The value of the string doesn't
1725  * change if an error is thrown.
1726  */
1727  basic_string&
1728  insert(size_type __pos, size_type __n, _CharT __c)
1729  { return _M_replace_aux(_M_check(__pos, "basic_string::insert"),
1730  size_type(0), __n, __c); }
1731 
1732  /**
1733  * @brief Insert one character.
1734  * @param __p Iterator referencing position in string to insert at.
1735  * @param __c The character to insert.
1736  * @return Iterator referencing newly inserted char.
1737  * @throw std::length_error If new length exceeds @c max_size().
1738  *
1739  * Inserts character @a __c at position referenced by @a __p.
1740  * If adding character causes the length to exceed max_size(),
1741  * length_error is thrown. If @a __p is beyond end of string,
1742  * out_of_range is thrown. The value of the string doesn't
1743  * change if an error is thrown.
1744  */
1745  iterator
1746  insert(__const_iterator __p, _CharT __c)
1747  {
1748  _GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1749  const size_type __pos = __p - begin();
1750  _M_replace_aux(__pos, size_type(0), size_type(1), __c);
1751  return iterator(_M_data() + __pos);
1752  }
1753 
1754 #if __cplusplus >= 201703L
1755  /**
1756  * @brief Insert a string_view.
1757  * @param __pos Position in string to insert at.
1758  * @param __svt The object convertible to string_view to insert.
1759  * @return Reference to this string.
1760  */
1761  template<typename _Tp>
1762  _If_sv<_Tp, basic_string&>
1763  insert(size_type __pos, const _Tp& __svt)
1764  {
1765  __sv_type __sv = __svt;
1766  return this->insert(__pos, __sv.data(), __sv.size());
1767  }
1768 
1769  /**
1770  * @brief Insert a string_view.
1771  * @param __pos1 Position in string to insert at.
1772  * @param __svt The object convertible to string_view to insert from.
1773  * @param __pos2 Start of characters in str to insert.
1774  * @param __n The number of characters to insert.
1775  * @return Reference to this string.
1776  */
1777  template<typename _Tp>
1778  _If_sv<_Tp, basic_string&>
1779  insert(size_type __pos1, const _Tp& __svt,
1780  size_type __pos2, size_type __n = npos)
1781  {
1782  __sv_type __sv = __svt;
1783  return this->replace(__pos1, size_type(0),
1784  __sv.data()
1785  + std::__sv_check(__sv.size(), __pos2, "basic_string::insert"),
1786  std::__sv_limit(__sv.size(), __pos2, __n));
1787  }
1788 #endif // C++17
1789 
1790  /**
1791  * @brief Remove characters.
1792  * @param __pos Index of first character to remove (default 0).
1793  * @param __n Number of characters to remove (default remainder).
1794  * @return Reference to this string.
1795  * @throw std::out_of_range If @a pos is beyond the end of this
1796  * string.
1797  *
1798  * Removes @a __n characters from this string starting at @a
1799  * __pos. The length of the string is reduced by @a __n. If
1800  * there are < @a __n characters to remove, the remainder of
1801  * the string is truncated. If @a __p is beyond end of string,
1802  * out_of_range is thrown. The value of the string doesn't
1803  * change if an error is thrown.
1804  */
1805  basic_string&
1806  erase(size_type __pos = 0, size_type __n = npos)
1807  {
1808  _M_check(__pos, "basic_string::erase");
1809  if (__n == npos)
1810  this->_M_set_length(__pos);
1811  else if (__n != 0)
1812  this->_M_erase(__pos, _M_limit(__pos, __n));
1813  return *this;
1814  }
1815 
1816  /**
1817  * @brief Remove one character.
1818  * @param __position Iterator referencing the character to remove.
1819  * @return iterator referencing same location after removal.
1820  *
1821  * Removes the character at @a __position from this string. The value
1822  * of the string doesn't change if an error is thrown.
1823  */
1824  iterator
1825  erase(__const_iterator __position)
1826  {
1827  _GLIBCXX_DEBUG_PEDASSERT(__position >= begin()
1828  && __position < end());
1829  const size_type __pos = __position - begin();
1830  this->_M_erase(__pos, size_type(1));
1831  return iterator(_M_data() + __pos);
1832  }
1833 
1834  /**
1835  * @brief Remove a range of characters.
1836  * @param __first Iterator referencing the first character to remove.
1837  * @param __last Iterator referencing the end of the range.
1838  * @return Iterator referencing location of first after removal.
1839  *
1840  * Removes the characters in the range [first,last) from this string.
1841  * The value of the string doesn't change if an error is thrown.
1842  */
1843  iterator
1844  erase(__const_iterator __first, __const_iterator __last)
1845  {
1846  _GLIBCXX_DEBUG_PEDASSERT(__first >= begin() && __first <= __last
1847  && __last <= end());
1848  const size_type __pos = __first - begin();
1849  if (__last == end())
1850  this->_M_set_length(__pos);
1851  else
1852  this->_M_erase(__pos, __last - __first);
1853  return iterator(this->_M_data() + __pos);
1854  }
1855 
1856 #if __cplusplus >= 201103L
1857  /**
1858  * @brief Remove the last character.
1859  *
1860  * The string must be non-empty.
1861  */
1862  void
1863  pop_back() noexcept
1864  {
1865  __glibcxx_assert(!empty());
1866  _M_erase(size() - 1, 1);
1867  }
1868 #endif // C++11
1869 
1870  /**
1871  * @brief Replace characters with value from another string.
1872  * @param __pos Index of first character to replace.
1873  * @param __n Number of characters to be replaced.
1874  * @param __str String to insert.
1875  * @return Reference to this string.
1876  * @throw std::out_of_range If @a pos is beyond the end of this
1877  * string.
1878  * @throw std::length_error If new length exceeds @c max_size().
1879  *
1880  * Removes the characters in the range [__pos,__pos+__n) from
1881  * this string. In place, the value of @a __str is inserted.
1882  * If @a __pos is beyond end of string, out_of_range is thrown.
1883  * If the length of the result exceeds max_size(), length_error
1884  * is thrown. The value of the string doesn't change if an
1885  * error is thrown.
1886  */
1887  basic_string&
1888  replace(size_type __pos, size_type __n, const basic_string& __str)
1889  { return this->replace(__pos, __n, __str._M_data(), __str.size()); }
1890 
1891  /**
1892  * @brief Replace characters with value from another string.
1893  * @param __pos1 Index of first character to replace.
1894  * @param __n1 Number of characters to be replaced.
1895  * @param __str String to insert.
1896  * @param __pos2 Index of first character of str to use.
1897  * @param __n2 Number of characters from str to use.
1898  * @return Reference to this string.
1899  * @throw std::out_of_range If @a __pos1 > size() or @a __pos2 >
1900  * __str.size().
1901  * @throw std::length_error If new length exceeds @c max_size().
1902  *
1903  * Removes the characters in the range [__pos1,__pos1 + n) from this
1904  * string. In place, the value of @a __str is inserted. If @a __pos is
1905  * beyond end of string, out_of_range is thrown. If the length of the
1906  * result exceeds max_size(), length_error is thrown. The value of the
1907  * string doesn't change if an error is thrown.
1908  */
1909  basic_string&
1910  replace(size_type __pos1, size_type __n1, const basic_string& __str,
1911  size_type __pos2, size_type __n2 = npos)
1912  { return this->replace(__pos1, __n1, __str._M_data()
1913  + __str._M_check(__pos2, "basic_string::replace"),
1914  __str._M_limit(__pos2, __n2)); }
1915 
1916  /**
1917  * @brief Replace characters with value of a C substring.
1918  * @param __pos Index of first character to replace.
1919  * @param __n1 Number of characters to be replaced.
1920  * @param __s C string to insert.
1921  * @param __n2 Number of characters from @a s to use.
1922  * @return Reference to this string.
1923  * @throw std::out_of_range If @a pos1 > size().
1924  * @throw std::length_error If new length exceeds @c max_size().
1925  *
1926  * Removes the characters in the range [__pos,__pos + __n1)
1927  * from this string. In place, the first @a __n2 characters of
1928  * @a __s are inserted, or all of @a __s if @a __n2 is too large. If
1929  * @a __pos is beyond end of string, out_of_range is thrown. If
1930  * the length of result exceeds max_size(), length_error is
1931  * thrown. The value of the string doesn't change if an error
1932  * is thrown.
1933  */
1934  basic_string&
1935  replace(size_type __pos, size_type __n1, const _CharT* __s,
1936  size_type __n2)
1937  {
1938  __glibcxx_requires_string_len(__s, __n2);
1939  return _M_replace(_M_check(__pos, "basic_string::replace"),
1940  _M_limit(__pos, __n1), __s, __n2);
1941  }
1942 
1943  /**
1944  * @brief Replace characters with value of a C string.
1945  * @param __pos Index of first character to replace.
1946  * @param __n1 Number of characters to be replaced.
1947  * @param __s C string to insert.
1948  * @return Reference to this string.
1949  * @throw std::out_of_range If @a pos > size().
1950  * @throw std::length_error If new length exceeds @c max_size().
1951  *
1952  * Removes the characters in the range [__pos,__pos + __n1)
1953  * from this string. In place, the characters of @a __s are
1954  * inserted. If @a __pos is beyond end of string, out_of_range
1955  * is thrown. If the length of result exceeds max_size(),
1956  * length_error is thrown. The value of the string doesn't
1957  * change if an error is thrown.
1958  */
1959  basic_string&
1960  replace(size_type __pos, size_type __n1, const _CharT* __s)
1961  {
1962  __glibcxx_requires_string(__s);
1963  return this->replace(__pos, __n1, __s, traits_type::length(__s));
1964  }
1965 
1966  /**
1967  * @brief Replace characters with multiple characters.
1968  * @param __pos Index of first character to replace.
1969  * @param __n1 Number of characters to be replaced.
1970  * @param __n2 Number of characters to insert.
1971  * @param __c Character to insert.
1972  * @return Reference to this string.
1973  * @throw std::out_of_range If @a __pos > size().
1974  * @throw std::length_error If new length exceeds @c max_size().
1975  *
1976  * Removes the characters in the range [pos,pos + n1) from this
1977  * string. In place, @a __n2 copies of @a __c are inserted.
1978  * If @a __pos is beyond end of string, out_of_range is thrown.
1979  * If the length of result exceeds max_size(), length_error is
1980  * thrown. The value of the string doesn't change if an error
1981  * is thrown.
1982  */
1983  basic_string&
1984  replace(size_type __pos, size_type __n1, size_type __n2, _CharT __c)
1985  { return _M_replace_aux(_M_check(__pos, "basic_string::replace"),
1986  _M_limit(__pos, __n1), __n2, __c); }
1987 
1988  /**
1989  * @brief Replace range of characters with string.
1990  * @param __i1 Iterator referencing start of range to replace.
1991  * @param __i2 Iterator referencing end of range to replace.
1992  * @param __str String value to insert.
1993  * @return Reference to this string.
1994  * @throw std::length_error If new length exceeds @c max_size().
1995  *
1996  * Removes the characters in the range [__i1,__i2). In place,
1997  * the value of @a __str is inserted. If the length of result
1998  * exceeds max_size(), length_error is thrown. The value of
1999  * the string doesn't change if an error is thrown.
2000  */
2001  basic_string&
2002  replace(__const_iterator __i1, __const_iterator __i2,
2003  const basic_string& __str)
2004  { return this->replace(__i1, __i2, __str._M_data(), __str.size()); }
2005 
2006  /**
2007  * @brief Replace range of characters with C substring.
2008  * @param __i1 Iterator referencing start of range to replace.
2009  * @param __i2 Iterator referencing end of range to replace.
2010  * @param __s C string value to insert.
2011  * @param __n Number of characters from s to insert.
2012  * @return Reference to this string.
2013  * @throw std::length_error If new length exceeds @c max_size().
2014  *
2015  * Removes the characters in the range [__i1,__i2). In place,
2016  * the first @a __n characters of @a __s are inserted. If the
2017  * length of result exceeds max_size(), length_error is thrown.
2018  * The value of the string doesn't change if an error is
2019  * thrown.
2020  */
2021  basic_string&
2022  replace(__const_iterator __i1, __const_iterator __i2,
2023  const _CharT* __s, size_type __n)
2024  {
2025  _GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2026  && __i2 <= end());
2027  return this->replace(__i1 - begin(), __i2 - __i1, __s, __n);
2028  }
2029 
2030  /**
2031  * @brief Replace range of characters with C string.
2032  * @param __i1 Iterator referencing start of range to replace.
2033  * @param __i2 Iterator referencing end of range to replace.
2034  * @param __s C string value to insert.
2035  * @return Reference to this string.
2036  * @throw std::length_error If new length exceeds @c max_size().
2037  *
2038  * Removes the characters in the range [__i1,__i2). In place,
2039  * the characters of @a __s are inserted. If the length of
2040  * result exceeds max_size(), length_error is thrown. The
2041  * value of the string doesn't change if an error is thrown.
2042  */
2043  basic_string&
2044  replace(__const_iterator __i1, __const_iterator __i2, const _CharT* __s)
2045  {
2046  __glibcxx_requires_string(__s);
2047  return this->replace(__i1, __i2, __s, traits_type::length(__s));
2048  }
2049 
2050  /**
2051  * @brief Replace range of characters with multiple characters
2052  * @param __i1 Iterator referencing start of range to replace.
2053  * @param __i2 Iterator referencing end of range to replace.
2054  * @param __n Number of characters to insert.
2055  * @param __c Character to insert.
2056  * @return Reference to this string.
2057  * @throw std::length_error If new length exceeds @c max_size().
2058  *
2059  * Removes the characters in the range [__i1,__i2). In place,
2060  * @a __n copies of @a __c are inserted. If the length of
2061  * result exceeds max_size(), length_error is thrown. The
2062  * value of the string doesn't change if an error is thrown.
2063  */
2064  basic_string&
2065  replace(__const_iterator __i1, __const_iterator __i2, size_type __n,
2066  _CharT __c)
2067  {
2068  _GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2069  && __i2 <= end());
2070  return _M_replace_aux(__i1 - begin(), __i2 - __i1, __n, __c);
2071  }
2072 
2073  /**
2074  * @brief Replace range of characters with range.
2075  * @param __i1 Iterator referencing start of range to replace.
2076  * @param __i2 Iterator referencing end of range to replace.
2077  * @param __k1 Iterator referencing start of range to insert.
2078  * @param __k2 Iterator referencing end of range to insert.
2079  * @return Reference to this string.
2080  * @throw std::length_error If new length exceeds @c max_size().
2081  *
2082  * Removes the characters in the range [__i1,__i2). In place,
2083  * characters in the range [__k1,__k2) are inserted. If the
2084  * length of result exceeds max_size(), length_error is thrown.
2085  * The value of the string doesn't change if an error is
2086  * thrown.
2087  */
2088 #if __cplusplus >= 201103L
2089  template<class _InputIterator,
2090  typename = std::_RequireInputIter<_InputIterator>>
2091  basic_string&
2092  replace(const_iterator __i1, const_iterator __i2,
2093  _InputIterator __k1, _InputIterator __k2)
2094  {
2095  _GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2096  && __i2 <= end());
2097  __glibcxx_requires_valid_range(__k1, __k2);
2098  return this->_M_replace_dispatch(__i1, __i2, __k1, __k2,
2099  std::__false_type());
2100  }
2101 #else
2102  template<class _InputIterator>
2103 #ifdef _GLIBCXX_DISAMBIGUATE_REPLACE_INST
2104  typename __enable_if_not_native_iterator<_InputIterator>::__type
2105 #else
2106  basic_string&
2107 #endif
2108  replace(iterator __i1, iterator __i2,
2109  _InputIterator __k1, _InputIterator __k2)
2110  {
2111  _GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2112  && __i2 <= end());
2113  __glibcxx_requires_valid_range(__k1, __k2);
2114  typedef typename std::__is_integer<_InputIterator>::__type _Integral;
2115  return _M_replace_dispatch(__i1, __i2, __k1, __k2, _Integral());
2116  }
2117 #endif
2118 
2119  // Specializations for the common case of pointer and iterator:
2120  // useful to avoid the overhead of temporary buffering in _M_replace.
2121  basic_string&
2122  replace(__const_iterator __i1, __const_iterator __i2,
2123  _CharT* __k1, _CharT* __k2)
2124  {
2125  _GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2126  && __i2 <= end());
2127  __glibcxx_requires_valid_range(__k1, __k2);
2128  return this->replace(__i1 - begin(), __i2 - __i1,
2129  __k1, __k2 - __k1);
2130  }
2131 
2132  basic_string&
2133  replace(__const_iterator __i1, __const_iterator __i2,
2134  const _CharT* __k1, const _CharT* __k2)
2135  {
2136  _GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2137  && __i2 <= end());
2138  __glibcxx_requires_valid_range(__k1, __k2);
2139  return this->replace(__i1 - begin(), __i2 - __i1,
2140  __k1, __k2 - __k1);
2141  }
2142 
2143  basic_string&
2144  replace(__const_iterator __i1, __const_iterator __i2,
2145  iterator __k1, iterator __k2)
2146  {
2147  _GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2148  && __i2 <= end());
2149  __glibcxx_requires_valid_range(__k1, __k2);
2150  return this->replace(__i1 - begin(), __i2 - __i1,
2151  __k1.base(), __k2 - __k1);
2152  }
2153 
2154  basic_string&
2155  replace(__const_iterator __i1, __const_iterator __i2,
2156  const_iterator __k1, const_iterator __k2)
2157  {
2158  _GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2159  && __i2 <= end());
2160  __glibcxx_requires_valid_range(__k1, __k2);
2161  return this->replace(__i1 - begin(), __i2 - __i1,
2162  __k1.base(), __k2 - __k1);
2163  }
2164 
2165 #if __cplusplus >= 201103L
2166  /**
2167  * @brief Replace range of characters with initializer_list.
2168  * @param __i1 Iterator referencing start of range to replace.
2169  * @param __i2 Iterator referencing end of range to replace.
2170  * @param __l The initializer_list of characters to insert.
2171  * @return Reference to this string.
2172  * @throw std::length_error If new length exceeds @c max_size().
2173  *
2174  * Removes the characters in the range [__i1,__i2). In place,
2175  * characters in the range [__k1,__k2) are inserted. If the
2176  * length of result exceeds max_size(), length_error is thrown.
2177  * The value of the string doesn't change if an error is
2178  * thrown.
2179  */
2180  basic_string& replace(const_iterator __i1, const_iterator __i2,
2181  initializer_list<_CharT> __l)
2182  { return this->replace(__i1, __i2, __l.begin(), __l.size()); }
2183 #endif // C++11
2184 
2185 #if __cplusplus >= 201703L
2186  /**
2187  * @brief Replace range of characters with string_view.
2188  * @param __pos The position to replace at.
2189  * @param __n The number of characters to replace.
2190  * @param __svt The object convertible to string_view to insert.
2191  * @return Reference to this string.
2192  */
2193  template<typename _Tp>
2194  _If_sv<_Tp, basic_string&>
2195  replace(size_type __pos, size_type __n, const _Tp& __svt)
2196  {
2197  __sv_type __sv = __svt;
2198  return this->replace(__pos, __n, __sv.data(), __sv.size());
2199  }
2200 
2201  /**
2202  * @brief Replace range of characters with string_view.
2203  * @param __pos1 The position to replace at.
2204  * @param __n1 The number of characters to replace.
2205  * @param __svt The object convertible to string_view to insert from.
2206  * @param __pos2 The position in the string_view to insert from.
2207  * @param __n2 The number of characters to insert.
2208  * @return Reference to this string.
2209  */
2210  template<typename _Tp>
2211  _If_sv<_Tp, basic_string&>
2212  replace(size_type __pos1, size_type __n1, const _Tp& __svt,
2213  size_type __pos2, size_type __n2 = npos)
2214  {
2215  __sv_type __sv = __svt;
2216  return this->replace(__pos1, __n1,
2217  __sv.data()
2218  + std::__sv_check(__sv.size(), __pos2, "basic_string::replace"),
2219  std::__sv_limit(__sv.size(), __pos2, __n2));
2220  }
2221 
2222  /**
2223  * @brief Replace range of characters with string_view.
2224  * @param __i1 An iterator referencing the start position
2225  to replace at.
2226  * @param __i2 An iterator referencing the end position
2227  for the replace.
2228  * @param __svt The object convertible to string_view to insert from.
2229  * @return Reference to this string.
2230  */
2231  template<typename _Tp>
2232  _If_sv<_Tp, basic_string&>
2233  replace(const_iterator __i1, const_iterator __i2, const _Tp& __svt)
2234  {
2235  __sv_type __sv = __svt;
2236  return this->replace(__i1 - begin(), __i2 - __i1, __sv);
2237  }
2238 #endif // C++17
2239 
2240  private:
2241  template<class _Integer>
2242  basic_string&
2243  _M_replace_dispatch(const_iterator __i1, const_iterator __i2,
2244  _Integer __n, _Integer __val, __true_type)
2245  { return _M_replace_aux(__i1 - begin(), __i2 - __i1, __n, __val); }
2246 
2247  template<class _InputIterator>
2248  basic_string&
2249  _M_replace_dispatch(const_iterator __i1, const_iterator __i2,
2250  _InputIterator __k1, _InputIterator __k2,
2251  __false_type);
2252 
2253  basic_string&
2254  _M_replace_aux(size_type __pos1, size_type __n1, size_type __n2,
2255  _CharT __c);
2256 
2257  basic_string&
2258  _M_replace(size_type __pos, size_type __len1, const _CharT* __s,
2259  const size_type __len2);
2260 
2261  basic_string&
2262  _M_append(const _CharT* __s, size_type __n);
2263 
2264  public:
2265 
2266  /**
2267  * @brief Copy substring into C string.
2268  * @param __s C string to copy value into.
2269  * @param __n Number of characters to copy.
2270  * @param __pos Index of first character to copy.
2271  * @return Number of characters actually copied
2272  * @throw std::out_of_range If __pos > size().
2273  *
2274  * Copies up to @a __n characters starting at @a __pos into the
2275  * C string @a __s. If @a __pos is %greater than size(),
2276  * out_of_range is thrown.
2277  */
2278  size_type
2279  copy(_CharT* __s, size_type __n, size_type __pos = 0) const;
2280 
2281  /**
2282  * @brief Swap contents with another string.
2283  * @param __s String to swap with.
2284  *
2285  * Exchanges the contents of this string with that of @a __s in constant
2286  * time.
2287  */
2288  void
2289  swap(basic_string& __s) _GLIBCXX_NOEXCEPT;
2290 
2291  // String operations:
2292  /**
2293  * @brief Return const pointer to null-terminated contents.
2294  *
2295  * This is a handle to internal data. Do not modify or dire things may
2296  * happen.
2297  */
2298  const _CharT*
2299  c_str() const _GLIBCXX_NOEXCEPT
2300  { return _M_data(); }
2301 
2302  /**
2303  * @brief Return const pointer to contents.
2304  *
2305  * This is a pointer to internal data. It is undefined to modify
2306  * the contents through the returned pointer. To get a pointer that
2307  * allows modifying the contents use @c &str[0] instead,
2308  * (or in C++17 the non-const @c str.data() overload).
2309  */
2310  const _CharT*
2311  data() const _GLIBCXX_NOEXCEPT
2312  { return _M_data(); }
2313 
2314 #if __cplusplus >= 201703L
2315  /**
2316  * @brief Return non-const pointer to contents.
2317  *
2318  * This is a pointer to the character sequence held by the string.
2319  * Modifying the characters in the sequence is allowed.
2320  */
2321  _CharT*
2322  data() noexcept
2323  { return _M_data(); }
2324 #endif
2325 
2326  /**
2327  * @brief Return copy of allocator used to construct this string.
2328  */
2329  allocator_type
2330  get_allocator() const _GLIBCXX_NOEXCEPT
2331  { return _M_get_allocator(); }
2332 
2333  /**
2334  * @brief Find position of a C substring.
2335  * @param __s C string to locate.
2336  * @param __pos Index of character to search from.
2337  * @param __n Number of characters from @a s to search for.
2338  * @return Index of start of first occurrence.
2339  *
2340  * Starting from @a __pos, searches forward for the first @a
2341  * __n characters in @a __s within this string. If found,
2342  * returns the index where it begins. If not found, returns
2343  * npos.
2344  */
2345  size_type
2346  find(const _CharT* __s, size_type __pos, size_type __n) const
2347  _GLIBCXX_NOEXCEPT;
2348 
2349  /**
2350  * @brief Find position of a string.
2351  * @param __str String to locate.
2352  * @param __pos Index of character to search from (default 0).
2353  * @return Index of start of first occurrence.
2354  *
2355  * Starting from @a __pos, searches forward for value of @a __str within
2356  * this string. If found, returns the index where it begins. If not
2357  * found, returns npos.
2358  */
2359  size_type
2360  find(const basic_string& __str, size_type __pos = 0) const
2361  _GLIBCXX_NOEXCEPT
2362  { return this->find(__str.data(), __pos, __str.size()); }
2363 
2364 #if __cplusplus >= 201703L
2365  /**
2366  * @brief Find position of a string_view.
2367  * @param __svt The object convertible to string_view to locate.
2368  * @param __pos Index of character to search from (default 0).
2369  * @return Index of start of first occurrence.
2370  */
2371  template<typename _Tp>
2372  _If_sv<_Tp, size_type>
2373  find(const _Tp& __svt, size_type __pos = 0) const
2374  noexcept(is_same<_Tp, __sv_type>::value)
2375  {
2376  __sv_type __sv = __svt;
2377  return this->find(__sv.data(), __pos, __sv.size());
2378  }
2379 #endif // C++17
2380 
2381  /**
2382  * @brief Find position of a C string.
2383  * @param __s C string to locate.
2384  * @param __pos Index of character to search from (default 0).
2385  * @return Index of start of first occurrence.
2386  *
2387  * Starting from @a __pos, searches forward for the value of @a
2388  * __s within this string. If found, returns the index where
2389  * it begins. If not found, returns npos.
2390  */
2391  size_type
2392  find(const _CharT* __s, size_type __pos = 0) const _GLIBCXX_NOEXCEPT
2393  {
2394  __glibcxx_requires_string(__s);
2395  return this->find(__s, __pos, traits_type::length(__s));
2396  }
2397 
2398  /**
2399  * @brief Find position of a character.
2400  * @param __c Character to locate.
2401  * @param __pos Index of character to search from (default 0).
2402  * @return Index of first occurrence.
2403  *
2404  * Starting from @a __pos, searches forward for @a __c within
2405  * this string. If found, returns the index where it was
2406  * found. If not found, returns npos.
2407  */
2408  size_type
2409  find(_CharT __c, size_type __pos = 0) const _GLIBCXX_NOEXCEPT;
2410 
2411  /**
2412  * @brief Find last position of a string.
2413  * @param __str String to locate.
2414  * @param __pos Index of character to search back from (default end).
2415  * @return Index of start of last occurrence.
2416  *
2417  * Starting from @a __pos, searches backward for value of @a
2418  * __str within this string. If found, returns the index where
2419  * it begins. If not found, returns npos.
2420  */
2421  size_type
2422  rfind(const basic_string& __str, size_type __pos = npos) const
2423  _GLIBCXX_NOEXCEPT
2424  { return this->rfind(__str.data(), __pos, __str.size()); }
2425 
2426 #if __cplusplus >= 201703L
2427  /**
2428  * @brief Find last position of a string_view.
2429  * @param __svt The object convertible to string_view to locate.
2430  * @param __pos Index of character to search back from (default end).
2431  * @return Index of start of last occurrence.
2432  */
2433  template<typename _Tp>
2434  _If_sv<_Tp, size_type>
2435  rfind(const _Tp& __svt, size_type __pos = npos) const
2436  noexcept(is_same<_Tp, __sv_type>::value)
2437  {
2438  __sv_type __sv = __svt;
2439  return this->rfind(__sv.data(), __pos, __sv.size());
2440  }
2441 #endif // C++17
2442 
2443  /**
2444  * @brief Find last position of a C substring.
2445  * @param __s C string to locate.
2446  * @param __pos Index of character to search back from.
2447  * @param __n Number of characters from s to search for.
2448  * @return Index of start of last occurrence.
2449  *
2450  * Starting from @a __pos, searches backward for the first @a
2451  * __n characters in @a __s within this string. If found,
2452  * returns the index where it begins. If not found, returns
2453  * npos.
2454  */
2455  size_type
2456  rfind(const _CharT* __s, size_type __pos, size_type __n) const
2457  _GLIBCXX_NOEXCEPT;
2458 
2459  /**
2460  * @brief Find last position of a C string.
2461  * @param __s C string to locate.
2462  * @param __pos Index of character to start search at (default end).
2463  * @return Index of start of last occurrence.
2464  *
2465  * Starting from @a __pos, searches backward for the value of
2466  * @a __s within this string. If found, returns the index
2467  * where it begins. If not found, returns npos.
2468  */
2469  size_type
2470  rfind(const _CharT* __s, size_type __pos = npos) const
2471  {
2472  __glibcxx_requires_string(__s);
2473  return this->rfind(__s, __pos, traits_type::length(__s));
2474  }
2475 
2476  /**
2477  * @brief Find last position of a character.
2478  * @param __c Character to locate.
2479  * @param __pos Index of character to search back from (default end).
2480  * @return Index of last occurrence.
2481  *
2482  * Starting from @a __pos, searches backward for @a __c within
2483  * this string. If found, returns the index where it was
2484  * found. If not found, returns npos.
2485  */
2486  size_type
2487  rfind(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT;
2488 
2489  /**
2490  * @brief Find position of a character of string.
2491  * @param __str String containing characters to locate.
2492  * @param __pos Index of character to search from (default 0).
2493  * @return Index of first occurrence.
2494  *
2495  * Starting from @a __pos, searches forward for one of the
2496  * characters of @a __str within this string. If found,
2497  * returns the index where it was found. If not found, returns
2498  * npos.
2499  */
2500  size_type
2501  find_first_of(const basic_string& __str, size_type __pos = 0) const
2502  _GLIBCXX_NOEXCEPT
2503  { return this->find_first_of(__str.data(), __pos, __str.size()); }
2504 
2505 #if __cplusplus >= 201703L
2506  /**
2507  * @brief Find position of a character of a string_view.
2508  * @param __svt An object convertible to string_view containing
2509  * characters to locate.
2510  * @param __pos Index of character to search from (default 0).
2511  * @return Index of first occurrence.
2512  */
2513  template<typename _Tp>
2514  _If_sv<_Tp, size_type>
2515  find_first_of(const _Tp& __svt, size_type __pos = 0) const
2516  noexcept(is_same<_Tp, __sv_type>::value)
2517  {
2518  __sv_type __sv = __svt;
2519  return this->find_first_of(__sv.data(), __pos, __sv.size());
2520  }
2521 #endif // C++17
2522 
2523  /**
2524  * @brief Find position of a character of C substring.
2525  * @param __s String containing characters to locate.
2526  * @param __pos Index of character to search from.
2527  * @param __n Number of characters from s to search for.
2528  * @return Index of first occurrence.
2529  *
2530  * Starting from @a __pos, searches forward for one of the
2531  * first @a __n characters of @a __s within this string. If
2532  * found, returns the index where it was found. If not found,
2533  * returns npos.
2534  */
2535  size_type
2536  find_first_of(const _CharT* __s, size_type __pos, size_type __n) const
2537  _GLIBCXX_NOEXCEPT;
2538 
2539  /**
2540  * @brief Find position of a character of C string.
2541  * @param __s String containing characters to locate.
2542  * @param __pos Index of character to search from (default 0).
2543  * @return Index of first occurrence.
2544  *
2545  * Starting from @a __pos, searches forward for one of the
2546  * characters of @a __s within this string. If found, returns
2547  * the index where it was found. If not found, returns npos.
2548  */
2549  size_type
2550  find_first_of(const _CharT* __s, size_type __pos = 0) const
2551  _GLIBCXX_NOEXCEPT
2552  {
2553  __glibcxx_requires_string(__s);
2554  return this->find_first_of(__s, __pos, traits_type::length(__s));
2555  }
2556 
2557  /**
2558  * @brief Find position of a character.
2559  * @param __c Character to locate.
2560  * @param __pos Index of character to search from (default 0).
2561  * @return Index of first occurrence.
2562  *
2563  * Starting from @a __pos, searches forward for the character
2564  * @a __c within this string. If found, returns the index
2565  * where it was found. If not found, returns npos.
2566  *
2567  * Note: equivalent to find(__c, __pos).
2568  */
2569  size_type
2570  find_first_of(_CharT __c, size_type __pos = 0) const _GLIBCXX_NOEXCEPT
2571  { return this->find(__c, __pos); }
2572 
2573  /**
2574  * @brief Find last position of a character of string.
2575  * @param __str String containing characters to locate.
2576  * @param __pos Index of character to search back from (default end).
2577  * @return Index of last occurrence.
2578  *
2579  * Starting from @a __pos, searches backward for one of the
2580  * characters of @a __str within this string. If found,
2581  * returns the index where it was found. If not found, returns
2582  * npos.
2583  */
2584  size_type
2585  find_last_of(const basic_string& __str, size_type __pos = npos) const
2586  _GLIBCXX_NOEXCEPT
2587  { return this->find_last_of(__str.data(), __pos, __str.size()); }
2588 
2589 #if __cplusplus >= 201703L
2590  /**
2591  * @brief Find last position of a character of string.
2592  * @param __svt An object convertible to string_view containing
2593  * characters to locate.
2594  * @param __pos Index of character to search back from (default end).
2595  * @return Index of last occurrence.
2596  */
2597  template<typename _Tp>
2598  _If_sv<_Tp, size_type>
2599  find_last_of(const _Tp& __svt, size_type __pos = npos) const
2600  noexcept(is_same<_Tp, __sv_type>::value)
2601  {
2602  __sv_type __sv = __svt;
2603  return this->find_last_of(__sv.data(), __pos, __sv.size());
2604  }
2605 #endif // C++17
2606 
2607  /**
2608  * @brief Find last position of a character of C substring.
2609  * @param __s C string containing characters to locate.
2610  * @param __pos Index of character to search back from.
2611  * @param __n Number of characters from s to search for.
2612  * @return Index of last occurrence.
2613  *
2614  * Starting from @a __pos, searches backward for one of the
2615  * first @a __n characters of @a __s within this string. If
2616  * found, returns the index where it was found. If not found,
2617  * returns npos.
2618  */
2619  size_type
2620  find_last_of(const _CharT* __s, size_type __pos, size_type __n) const
2621  _GLIBCXX_NOEXCEPT;
2622 
2623  /**
2624  * @brief Find last position of a character of C string.
2625  * @param __s C string containing characters to locate.
2626  * @param __pos Index of character to search back from (default end).
2627  * @return Index of last occurrence.
2628  *
2629  * Starting from @a __pos, searches backward for one of the
2630  * characters of @a __s within this string. If found, returns
2631  * the index where it was found. If not found, returns npos.
2632  */
2633  size_type
2634  find_last_of(const _CharT* __s, size_type __pos = npos) const
2635  _GLIBCXX_NOEXCEPT
2636  {
2637  __glibcxx_requires_string(__s);
2638  return this->find_last_of(__s, __pos, traits_type::length(__s));
2639  }
2640 
2641  /**
2642  * @brief Find last position of a character.
2643  * @param __c Character to locate.
2644  * @param __pos Index of character to search back from (default end).
2645  * @return Index of last occurrence.
2646  *
2647  * Starting from @a __pos, searches backward for @a __c within
2648  * this string. If found, returns the index where it was
2649  * found. If not found, returns npos.
2650  *
2651  * Note: equivalent to rfind(__c, __pos).
2652  */
2653  size_type
2654  find_last_of(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT
2655  { return this->rfind(__c, __pos); }
2656 
2657  /**
2658  * @brief Find position of a character not in string.
2659  * @param __str String containing characters to avoid.
2660  * @param __pos Index of character to search from (default 0).
2661  * @return Index of first occurrence.
2662  *
2663  * Starting from @a __pos, searches forward for a character not contained
2664  * in @a __str within this string. If found, returns the index where it
2665  * was found. If not found, returns npos.
2666  */
2667  size_type
2668  find_first_not_of(const basic_string& __str, size_type __pos = 0) const
2669  _GLIBCXX_NOEXCEPT
2670  { return this->find_first_not_of(__str.data(), __pos, __str.size()); }
2671 
2672 #if __cplusplus >= 201703L
2673  /**
2674  * @brief Find position of a character not in a string_view.
2675  * @param __svt A object convertible to string_view containing
2676  * characters to avoid.
2677  * @param __pos Index of character to search from (default 0).
2678  * @return Index of first occurrence.
2679  */
2680  template<typename _Tp>
2681  _If_sv<_Tp, size_type>
2682  find_first_not_of(const _Tp& __svt, size_type __pos = 0) const
2683  noexcept(is_same<_Tp, __sv_type>::value)
2684  {
2685  __sv_type __sv = __svt;
2686  return this->find_first_not_of(__sv.data(), __pos, __sv.size());
2687  }
2688 #endif // C++17
2689 
2690  /**
2691  * @brief Find position of a character not in C substring.
2692  * @param __s C string containing characters to avoid.
2693  * @param __pos Index of character to search from.
2694  * @param __n Number of characters from __s to consider.
2695  * @return Index of first occurrence.
2696  *
2697  * Starting from @a __pos, searches forward for a character not
2698  * contained in the first @a __n characters of @a __s within
2699  * this string. If found, returns the index where it was
2700  * found. If not found, returns npos.
2701  */
2702  size_type
2703  find_first_not_of(const _CharT* __s, size_type __pos,
2704  size_type __n) const _GLIBCXX_NOEXCEPT;
2705 
2706  /**
2707  * @brief Find position of a character not in C string.
2708  * @param __s C string containing characters to avoid.
2709  * @param __pos Index of character to search from (default 0).
2710  * @return Index of first occurrence.
2711  *
2712  * Starting from @a __pos, searches forward for a character not
2713  * contained in @a __s within this string. If found, returns
2714  * the index where it was found. If not found, returns npos.
2715  */
2716  size_type
2717  find_first_not_of(const _CharT* __s, size_type __pos = 0) const
2718  _GLIBCXX_NOEXCEPT
2719  {
2720  __glibcxx_requires_string(__s);
2721  return this->find_first_not_of(__s, __pos, traits_type::length(__s));
2722  }
2723 
2724  /**
2725  * @brief Find position of a different character.
2726  * @param __c Character to avoid.
2727  * @param __pos Index of character to search from (default 0).
2728  * @return Index of first occurrence.
2729  *
2730  * Starting from @a __pos, searches forward for a character
2731  * other than @a __c within this string. If found, returns the
2732  * index where it was found. If not found, returns npos.
2733  */
2734  size_type
2735  find_first_not_of(_CharT __c, size_type __pos = 0) const
2736  _GLIBCXX_NOEXCEPT;
2737 
2738  /**
2739  * @brief Find last position of a character not in string.
2740  * @param __str String containing characters to avoid.
2741  * @param __pos Index of character to search back from (default end).
2742  * @return Index of last occurrence.
2743  *
2744  * Starting from @a __pos, searches backward for a character
2745  * not contained in @a __str within this string. If found,
2746  * returns the index where it was found. If not found, returns
2747  * npos.
2748  */
2749  size_type
2750  find_last_not_of(const basic_string& __str, size_type __pos = npos) const
2751  _GLIBCXX_NOEXCEPT
2752  { return this->find_last_not_of(__str.data(), __pos, __str.size()); }
2753 
2754 #if __cplusplus >= 201703L
2755  /**
2756  * @brief Find last position of a character not in a string_view.
2757  * @param __svt An object convertible to string_view containing
2758  * characters to avoid.
2759  * @param __pos Index of character to search back from (default end).
2760  * @return Index of last occurrence.
2761  */
2762  template<typename _Tp>
2763  _If_sv<_Tp, size_type>
2764  find_last_not_of(const _Tp& __svt, size_type __pos = npos) const
2765  noexcept(is_same<_Tp, __sv_type>::value)
2766  {
2767  __sv_type __sv = __svt;
2768  return this->find_last_not_of(__sv.data(), __pos, __sv.size());
2769  }
2770 #endif // C++17
2771 
2772  /**
2773  * @brief Find last position of a character not in C substring.
2774  * @param __s C string containing characters to avoid.
2775  * @param __pos Index of character to search back from.
2776  * @param __n Number of characters from s to consider.
2777  * @return Index of last occurrence.
2778  *
2779  * Starting from @a __pos, searches backward for a character not
2780  * contained in the first @a __n characters of @a __s within this string.
2781  * If found, returns the index where it was found. If not found,
2782  * returns npos.
2783  */
2784  size_type
2785  find_last_not_of(const _CharT* __s, size_type __pos,
2786  size_type __n) const _GLIBCXX_NOEXCEPT;
2787  /**
2788  * @brief Find last position of a character not in C string.
2789  * @param __s C string containing characters to avoid.
2790  * @param __pos Index of character to search back from (default end).
2791  * @return Index of last occurrence.
2792  *
2793  * Starting from @a __pos, searches backward for a character
2794  * not contained in @a __s within this string. If found,
2795  * returns the index where it was found. If not found, returns
2796  * npos.
2797  */
2798  size_type
2799  find_last_not_of(const _CharT* __s, size_type __pos = npos) const
2800  _GLIBCXX_NOEXCEPT
2801  {
2802  __glibcxx_requires_string(__s);
2803  return this->find_last_not_of(__s, __pos, traits_type::length(__s));
2804  }
2805 
2806  /**
2807  * @brief Find last position of a different character.
2808  * @param __c Character to avoid.
2809  * @param __pos Index of character to search back from (default end).
2810  * @return Index of last occurrence.
2811  *
2812  * Starting from @a __pos, searches backward for a character other than
2813  * @a __c within this string. If found, returns the index where it was
2814  * found. If not found, returns npos.
2815  */
2816  size_type
2817  find_last_not_of(_CharT __c, size_type __pos = npos) const
2818  _GLIBCXX_NOEXCEPT;
2819 
2820  /**
2821  * @brief Get a substring.
2822  * @param __pos Index of first character (default 0).
2823  * @param __n Number of characters in substring (default remainder).
2824  * @return The new string.
2825  * @throw std::out_of_range If __pos > size().
2826  *
2827  * Construct and return a new string using the @a __n
2828  * characters starting at @a __pos. If the string is too
2829  * short, use the remainder of the characters. If @a __pos is
2830  * beyond the end of the string, out_of_range is thrown.
2831  */
2832  basic_string
2833  substr(size_type __pos = 0, size_type __n = npos) const
2834  { return basic_string(*this,
2835  _M_check(__pos, "basic_string::substr"), __n); }
2836 
2837  /**
2838  * @brief Compare to a string.
2839  * @param __str String to compare against.
2840  * @return Integer < 0, 0, or > 0.
2841  *
2842  * Returns an integer < 0 if this string is ordered before @a
2843  * __str, 0 if their values are equivalent, or > 0 if this
2844  * string is ordered after @a __str. Determines the effective
2845  * length rlen of the strings to compare as the smallest of
2846  * size() and str.size(). The function then compares the two
2847  * strings by calling traits::compare(data(), str.data(),rlen).
2848  * If the result of the comparison is nonzero returns it,
2849  * otherwise the shorter one is ordered first.
2850  */
2851  int
2852  compare(const basic_string& __str) const
2853  {
2854  const size_type __size = this->size();
2855  const size_type __osize = __str.size();
2856  const size_type __len = std::min(__size, __osize);
2857 
2858  int __r = traits_type::compare(_M_data(), __str.data(), __len);
2859  if (!__r)
2860  __r = _S_compare(__size, __osize);
2861  return __r;
2862  }
2863 
2864 #if __cplusplus >= 201703L
2865  /**
2866  * @brief Compare to a string_view.
2867  * @param __svt An object convertible to string_view to compare against.
2868  * @return Integer < 0, 0, or > 0.
2869  */
2870  template<typename _Tp>
2871  _If_sv<_Tp, int>
2872  compare(const _Tp& __svt) const
2873  noexcept(is_same<_Tp, __sv_type>::value)
2874  {
2875  __sv_type __sv = __svt;
2876  const size_type __size = this->size();
2877  const size_type __osize = __sv.size();
2878  const size_type __len = std::min(__size, __osize);
2879 
2880  int __r = traits_type::compare(_M_data(), __sv.data(), __len);
2881  if (!__r)
2882  __r = _S_compare(__size, __osize);
2883  return __r;
2884  }
2885 
2886  /**
2887  * @brief Compare to a string_view.
2888  * @param __pos A position in the string to start comparing from.
2889  * @param __n The number of characters to compare.
2890  * @param __svt An object convertible to string_view to compare
2891  * against.
2892  * @return Integer < 0, 0, or > 0.
2893  */
2894  template<typename _Tp>
2895  _If_sv<_Tp, int>
2896  compare(size_type __pos, size_type __n, const _Tp& __svt) const
2897  noexcept(is_same<_Tp, __sv_type>::value)
2898  {
2899  __sv_type __sv = __svt;
2900  return __sv_type(*this).substr(__pos, __n).compare(__sv);
2901  }
2902 
2903  /**
2904  * @brief Compare to a string_view.
2905  * @param __pos1 A position in the string to start comparing from.
2906  * @param __n1 The number of characters to compare.
2907  * @param __svt An object convertible to string_view to compare
2908  * against.
2909  * @param __pos2 A position in the string_view to start comparing from.
2910  * @param __n2 The number of characters to compare.
2911  * @return Integer < 0, 0, or > 0.
2912  */
2913  template<typename _Tp>
2914  _If_sv<_Tp, int>
2915  compare(size_type __pos1, size_type __n1, const _Tp& __svt,
2916  size_type __pos2, size_type __n2 = npos) const
2917  noexcept(is_same<_Tp, __sv_type>::value)
2918  {
2919  __sv_type __sv = __svt;
2920  return __sv_type(*this)
2921  .substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
2922  }
2923 #endif // C++17
2924 
2925  /**
2926  * @brief Compare substring to a string.
2927  * @param __pos Index of first character of substring.
2928  * @param __n Number of characters in substring.
2929  * @param __str String to compare against.
2930  * @return Integer < 0, 0, or > 0.
2931  *
2932  * Form the substring of this string from the @a __n characters
2933  * starting at @a __pos. Returns an integer < 0 if the
2934  * substring is ordered before @a __str, 0 if their values are
2935  * equivalent, or > 0 if the substring is ordered after @a
2936  * __str. Determines the effective length rlen of the strings
2937  * to compare as the smallest of the length of the substring
2938  * and @a __str.size(). The function then compares the two
2939  * strings by calling
2940  * traits::compare(substring.data(),str.data(),rlen). If the
2941  * result of the comparison is nonzero returns it, otherwise
2942  * the shorter one is ordered first.
2943  */
2944  int
2945  compare(size_type __pos, size_type __n, const basic_string& __str) const;
2946 
2947  /**
2948  * @brief Compare substring to a substring.
2949  * @param __pos1 Index of first character of substring.
2950  * @param __n1 Number of characters in substring.
2951  * @param __str String to compare against.
2952  * @param __pos2 Index of first character of substring of str.
2953  * @param __n2 Number of characters in substring of str.
2954  * @return Integer < 0, 0, or > 0.
2955  *
2956  * Form the substring of this string from the @a __n1
2957  * characters starting at @a __pos1. Form the substring of @a
2958  * __str from the @a __n2 characters starting at @a __pos2.
2959  * Returns an integer < 0 if this substring is ordered before
2960  * the substring of @a __str, 0 if their values are equivalent,
2961  * or > 0 if this substring is ordered after the substring of
2962  * @a __str. Determines the effective length rlen of the
2963  * strings to compare as the smallest of the lengths of the
2964  * substrings. The function then compares the two strings by
2965  * calling
2966  * traits::compare(substring.data(),str.substr(pos2,n2).data(),rlen).
2967  * If the result of the comparison is nonzero returns it,
2968  * otherwise the shorter one is ordered first.
2969  */
2970  int
2971  compare(size_type __pos1, size_type __n1, const basic_string& __str,
2972  size_type __pos2, size_type __n2 = npos) const;
2973 
2974  /**
2975  * @brief Compare to a C string.
2976  * @param __s C string to compare against.
2977  * @return Integer < 0, 0, or > 0.
2978  *
2979  * Returns an integer < 0 if this string is ordered before @a __s, 0 if
2980  * their values are equivalent, or > 0 if this string is ordered after
2981  * @a __s. Determines the effective length rlen of the strings to
2982  * compare as the smallest of size() and the length of a string
2983  * constructed from @a __s. The function then compares the two strings
2984  * by calling traits::compare(data(),s,rlen). If the result of the
2985  * comparison is nonzero returns it, otherwise the shorter one is
2986  * ordered first.
2987  */
2988  int
2989  compare(const _CharT* __s) const _GLIBCXX_NOEXCEPT;
2990 
2991  // _GLIBCXX_RESOLVE_LIB_DEFECTS
2992  // 5 String::compare specification questionable
2993  /**
2994  * @brief Compare substring to a C string.
2995  * @param __pos Index of first character of substring.
2996  * @param __n1 Number of characters in substring.
2997  * @param __s C string to compare against.
2998  * @return Integer < 0, 0, or > 0.
2999  *
3000  * Form the substring of this string from the @a __n1
3001  * characters starting at @a pos. Returns an integer < 0 if
3002  * the substring is ordered before @a __s, 0 if their values
3003  * are equivalent, or > 0 if the substring is ordered after @a
3004  * __s. Determines the effective length rlen of the strings to
3005  * compare as the smallest of the length of the substring and
3006  * the length of a string constructed from @a __s. The
3007  * function then compares the two string by calling
3008  * traits::compare(substring.data(),__s,rlen). If the result of
3009  * the comparison is nonzero returns it, otherwise the shorter
3010  * one is ordered first.
3011  */
3012  int
3013  compare(size_type __pos, size_type __n1, const _CharT* __s) const;
3014 
3015  /**
3016  * @brief Compare substring against a character %array.
3017  * @param __pos Index of first character of substring.
3018  * @param __n1 Number of characters in substring.
3019  * @param __s character %array to compare against.
3020  * @param __n2 Number of characters of s.
3021  * @return Integer < 0, 0, or > 0.
3022  *
3023  * Form the substring of this string from the @a __n1
3024  * characters starting at @a __pos. Form a string from the
3025  * first @a __n2 characters of @a __s. Returns an integer < 0
3026  * if this substring is ordered before the string from @a __s,
3027  * 0 if their values are equivalent, or > 0 if this substring
3028  * is ordered after the string from @a __s. Determines the
3029  * effective length rlen of the strings to compare as the
3030  * smallest of the length of the substring and @a __n2. The
3031  * function then compares the two strings by calling
3032  * traits::compare(substring.data(),s,rlen). If the result of
3033  * the comparison is nonzero returns it, otherwise the shorter
3034  * one is ordered first.
3035  *
3036  * NB: s must have at least n2 characters, &apos;\\0&apos; has
3037  * no special meaning.
3038  */
3039  int
3040  compare(size_type __pos, size_type __n1, const _CharT* __s,
3041  size_type __n2) const;
3042 
3043 #if __cplusplus > 201703L
3044  bool
3045  starts_with(basic_string_view<_CharT, _Traits> __x) const noexcept
3046  { return __sv_type(this->data(), this->size()).starts_with(__x); }
3047 
3048  bool
3049  starts_with(_CharT __x) const noexcept
3050  { return __sv_type(this->data(), this->size()).starts_with(__x); }
3051 
3052  bool
3053  starts_with(const _CharT* __x) const noexcept
3054  { return __sv_type(this->data(), this->size()).starts_with(__x); }
3055 
3056  bool
3057  ends_with(basic_string_view<_CharT, _Traits> __x) const noexcept
3058  { return __sv_type(this->data(), this->size()).ends_with(__x); }
3059 
3060  bool
3061  ends_with(_CharT __x) const noexcept
3062  { return __sv_type(this->data(), this->size()).ends_with(__x); }
3063 
3064  bool
3065  ends_with(const _CharT* __x) const noexcept
3066  { return __sv_type(this->data(), this->size()).ends_with(__x); }
3067 #endif // C++20
3068 
3069  // Allow basic_stringbuf::__xfer_bufptrs to call _M_length:
3070  template<typename, typename, typename> friend class basic_stringbuf;
3071  };
3072 _GLIBCXX_END_NAMESPACE_CXX11
3073 #else // !_GLIBCXX_USE_CXX11_ABI
3074  // Reference-counted COW string implentation
3075 
3076  /**
3077  * @class basic_string basic_string.h <string>
3078  * @brief Managing sequences of characters and character-like objects.
3079  *
3080  * @ingroup strings
3081  * @ingroup sequences
3082  *
3083  * @tparam _CharT Type of character
3084  * @tparam _Traits Traits for character type, defaults to
3085  * char_traits<_CharT>.
3086  * @tparam _Alloc Allocator type, defaults to allocator<_CharT>.
3087  *
3088  * Meets the requirements of a <a href="tables.html#65">container</a>, a
3089  * <a href="tables.html#66">reversible container</a>, and a
3090  * <a href="tables.html#67">sequence</a>. Of the
3091  * <a href="tables.html#68">optional sequence requirements</a>, only
3092  * @c push_back, @c at, and @c %array access are supported.
3093  *
3094  * @doctodo
3095  *
3096  *
3097  * Documentation? What's that?
3098  * Nathan Myers <ncm@cantrip.org>.
3099  *
3100  * A string looks like this:
3101  *
3102  * @code
3103  * [_Rep]
3104  * _M_length
3105  * [basic_string<char_type>] _M_capacity
3106  * _M_dataplus _M_refcount
3107  * _M_p ----------------> unnamed array of char_type
3108  * @endcode
3109  *
3110  * Where the _M_p points to the first character in the string, and
3111  * you cast it to a pointer-to-_Rep and subtract 1 to get a
3112  * pointer to the header.
3113  *
3114  * This approach has the enormous advantage that a string object
3115  * requires only one allocation. All the ugliness is confined
3116  * within a single %pair of inline functions, which each compile to
3117  * a single @a add instruction: _Rep::_M_data(), and
3118  * string::_M_rep(); and the allocation function which gets a
3119  * block of raw bytes and with room enough and constructs a _Rep
3120  * object at the front.
3121  *
3122  * The reason you want _M_data pointing to the character %array and
3123  * not the _Rep is so that the debugger can see the string
3124  * contents. (Probably we should add a non-inline member to get
3125  * the _Rep for the debugger to use, so users can check the actual
3126  * string length.)
3127  *
3128  * Note that the _Rep object is a POD so that you can have a
3129  * static <em>empty string</em> _Rep object already @a constructed before
3130  * static constructors have run. The reference-count encoding is
3131  * chosen so that a 0 indicates one reference, so you never try to
3132  * destroy the empty-string _Rep object.
3133  *
3134  * All but the last paragraph is considered pretty conventional
3135  * for a C++ string implementation.
3136  */
3137  // 21.3 Template class basic_string
3138  template<typename _CharT, typename _Traits, typename _Alloc>
3140  {
3142  rebind<_CharT>::other _CharT_alloc_type;
3144 
3145  // Types:
3146  public:
3147  typedef _Traits traits_type;
3148  typedef typename _Traits::char_type value_type;
3149  typedef _Alloc allocator_type;
3150  typedef typename _CharT_alloc_type::size_type size_type;
3151  typedef typename _CharT_alloc_type::difference_type difference_type;
3152 #if __cplusplus < 201103L
3153  typedef typename _CharT_alloc_type::reference reference;
3154  typedef typename _CharT_alloc_type::const_reference const_reference;
3155 #else
3156  typedef value_type& reference;
3157  typedef const value_type& const_reference;
3158 #endif
3159  typedef typename _CharT_alloc_traits::pointer pointer;
3160  typedef typename _CharT_alloc_traits::const_pointer const_pointer;
3161  typedef __gnu_cxx::__normal_iterator<pointer, basic_string> iterator;
3162  typedef __gnu_cxx::__normal_iterator<const_pointer, basic_string>
3163  const_iterator;
3166 
3167  protected:
3168  // type used for positions in insert, erase etc.
3169  typedef iterator __const_iterator;
3170 
3171  private:
3172  // _Rep: string representation
3173  // Invariants:
3174  // 1. String really contains _M_length + 1 characters: due to 21.3.4
3175  // must be kept null-terminated.
3176  // 2. _M_capacity >= _M_length
3177  // Allocated memory is always (_M_capacity + 1) * sizeof(_CharT).
3178  // 3. _M_refcount has three states:
3179  // -1: leaked, one reference, no ref-copies allowed, non-const.
3180  // 0: one reference, non-const.
3181  // n>0: n + 1 references, operations require a lock, const.
3182  // 4. All fields==0 is an empty string, given the extra storage
3183  // beyond-the-end for a null terminator; thus, the shared
3184  // empty string representation needs no constructor.
3185 
3186  struct _Rep_base
3187  {
3188  size_type _M_length;
3189  size_type _M_capacity;
3190  _Atomic_word _M_refcount;
3191  };
3192 
3193  struct _Rep : _Rep_base
3194  {
3195  // Types:
3197  rebind<char>::other _Raw_bytes_alloc;
3198 
3199  // (Public) Data members:
3200 
3201  // The maximum number of individual char_type elements of an
3202  // individual string is determined by _S_max_size. This is the
3203  // value that will be returned by max_size(). (Whereas npos
3204  // is the maximum number of bytes the allocator can allocate.)
3205  // If one was to divvy up the theoretical largest size string,
3206  // with a terminating character and m _CharT elements, it'd
3207  // look like this:
3208  // npos = sizeof(_Rep) + (m * sizeof(_CharT)) + sizeof(_CharT)
3209  // Solving for m:
3210  // m = ((npos - sizeof(_Rep))/sizeof(CharT)) - 1
3211  // In addition, this implementation quarters this amount.
3212  static const size_type _S_max_size;
3213  static const _CharT _S_terminal;
3214 
3215  // The following storage is init'd to 0 by the linker, resulting
3216  // (carefully) in an empty string with one reference.
3217  static size_type _S_empty_rep_storage[];
3218 
3219  static _Rep&
3220  _S_empty_rep() _GLIBCXX_NOEXCEPT
3221  {
3222  // NB: Mild hack to avoid strict-aliasing warnings. Note that
3223  // _S_empty_rep_storage is never modified and the punning should
3224  // be reasonably safe in this case.
3225  void* __p = reinterpret_cast<void*>(&_S_empty_rep_storage);
3226  return *reinterpret_cast<_Rep*>(__p);
3227  }
3228 
3229  bool
3230  _M_is_leaked() const _GLIBCXX_NOEXCEPT
3231  {
3232 #if defined(__GTHREADS)
3233  // _M_refcount is mutated concurrently by _M_refcopy/_M_dispose,
3234  // so we need to use an atomic load. However, _M_is_leaked
3235  // predicate does not change concurrently (i.e. the string is either
3236  // leaked or not), so a relaxed load is enough.
3237  return __atomic_load_n(&this->_M_refcount, __ATOMIC_RELAXED) < 0;
3238 #else
3239  return this->_M_refcount < 0;
3240 #endif
3241  }
3242 
3243  bool
3244  _M_is_shared() const _GLIBCXX_NOEXCEPT
3245  {
3246 #if defined(__GTHREADS)
3247  // _M_refcount is mutated concurrently by _M_refcopy/_M_dispose,
3248  // so we need to use an atomic load. Another thread can drop last
3249  // but one reference concurrently with this check, so we need this
3250  // load to be acquire to synchronize with release fetch_and_add in
3251  // _M_dispose.
3252  return __atomic_load_n(&this->_M_refcount, __ATOMIC_ACQUIRE) > 0;
3253 #else
3254  return this->_M_refcount > 0;
3255 #endif
3256  }
3257 
3258  void
3259  _M_set_leaked() _GLIBCXX_NOEXCEPT
3260  { this->_M_refcount = -1; }
3261 
3262  void
3263  _M_set_sharable() _GLIBCXX_NOEXCEPT
3264  { this->_M_refcount = 0; }
3265 
3266  void
3267  _M_set_length_and_sharable(size_type __n) _GLIBCXX_NOEXCEPT
3268  {
3269 #if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3270  if (__builtin_expect(this != &_S_empty_rep(), false))
3271 #endif
3272  {
3273  this->_M_set_sharable(); // One reference.
3274  this->_M_length = __n;
3275  traits_type::assign(this->_M_refdata()[__n], _S_terminal);
3276  // grrr. (per 21.3.4)
3277  // You cannot leave those LWG people alone for a second.
3278  }
3279  }
3280 
3281  _CharT*
3282  _M_refdata() throw()
3283  { return reinterpret_cast<_CharT*>(this + 1); }
3284 
3285  _CharT*
3286  _M_grab(const _Alloc& __alloc1, const _Alloc& __alloc2)
3287  {
3288  return (!_M_is_leaked() && __alloc1 == __alloc2)
3289  ? _M_refcopy() : _M_clone(__alloc1);
3290  }
3291 
3292  // Create & Destroy
3293  static _Rep*
3294  _S_create(size_type, size_type, const _Alloc&);
3295 
3296  void
3297  _M_dispose(const _Alloc& __a) _GLIBCXX_NOEXCEPT
3298  {
3299 #if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3300  if (__builtin_expect(this != &_S_empty_rep(), false))
3301 #endif
3302  {
3303  // Be race-detector-friendly. For more info see bits/c++config.
3304  _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&this->_M_refcount);
3305  // Decrement of _M_refcount is acq_rel, because:
3306  // - all but last decrements need to release to synchronize with
3307  // the last decrement that will delete the object.
3308  // - the last decrement needs to acquire to synchronize with
3309  // all the previous decrements.
3310  // - last but one decrement needs to release to synchronize with
3311  // the acquire load in _M_is_shared that will conclude that
3312  // the object is not shared anymore.
3313  if (__gnu_cxx::__exchange_and_add_dispatch(&this->_M_refcount,
3314  -1) <= 0)
3315  {
3316  _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&this->_M_refcount);
3317  _M_destroy(__a);
3318  }
3319  }
3320  } // XXX MT
3321 
3322  void
3323  _M_destroy(const _Alloc&) throw();
3324 
3325  _CharT*
3326  _M_refcopy() throw()
3327  {
3328 #if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3329  if (__builtin_expect(this != &_S_empty_rep(), false))
3330 #endif
3331  __gnu_cxx::__atomic_add_dispatch(&this->_M_refcount, 1);
3332  return _M_refdata();
3333  } // XXX MT
3334 
3335  _CharT*
3336  _M_clone(const _Alloc&, size_type __res = 0);
3337  };
3338 
3339  // Use empty-base optimization: http://www.cantrip.org/emptyopt.html
3340  struct _Alloc_hider : _Alloc
3341  {
3342  _Alloc_hider(_CharT* __dat, const _Alloc& __a) _GLIBCXX_NOEXCEPT
3343  : _Alloc(__a), _M_p(__dat) { }
3344 
3345  _CharT* _M_p; // The actual data.
3346  };
3347 
3348  public:
3349  // Data Members (public):
3350  // NB: This is an unsigned type, and thus represents the maximum
3351  // size that the allocator can hold.
3352  /// Value returned by various member functions when they fail.
3353  static const size_type npos = static_cast<size_type>(-1);
3354 
3355  private:
3356  // Data Members (private):
3357  mutable _Alloc_hider _M_dataplus;
3358 
3359  _CharT*
3360  _M_data() const _GLIBCXX_NOEXCEPT
3361  { return _M_dataplus._M_p; }
3362 
3363  _CharT*
3364  _M_data(_CharT* __p) _GLIBCXX_NOEXCEPT
3365  { return (_M_dataplus._M_p = __p); }
3366 
3367  _Rep*
3368  _M_rep() const _GLIBCXX_NOEXCEPT
3369  { return &((reinterpret_cast<_Rep*> (_M_data()))[-1]); }
3370 
3371  // For the internal use we have functions similar to `begin'/`end'
3372  // but they do not call _M_leak.
3373  iterator
3374  _M_ibegin() const _GLIBCXX_NOEXCEPT
3375  { return iterator(_M_data()); }
3376 
3377  iterator
3378  _M_iend() const _GLIBCXX_NOEXCEPT
3379  { return iterator(_M_data() + this->size()); }
3380 
3381  void
3382  _M_leak() // for use in begin() & non-const op[]
3383  {
3384  if (!_M_rep()->_M_is_leaked())
3385  _M_leak_hard();
3386  }
3387 
3388  size_type
3389  _M_check(size_type __pos, const char* __s) const
3390  {
3391  if (__pos > this->size())
3392  __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > "
3393  "this->size() (which is %zu)"),
3394  __s, __pos, this->size());
3395  return __pos;
3396  }
3397 
3398  void
3399  _M_check_length(size_type __n1, size_type __n2, const char* __s) const
3400  {
3401  if (this->max_size() - (this->size() - __n1) < __n2)
3402  __throw_length_error(__N(__s));
3403  }
3404 
3405  // NB: _M_limit doesn't check for a bad __pos value.
3406  size_type
3407  _M_limit(size_type __pos, size_type __off) const _GLIBCXX_NOEXCEPT
3408  {
3409  const bool __testoff = __off < this->size() - __pos;
3410  return __testoff ? __off : this->size() - __pos;
3411  }
3412 
3413  // True if _Rep and source do not overlap.
3414  bool
3415  _M_disjunct(const _CharT* __s) const _GLIBCXX_NOEXCEPT
3416  {
3417  return (less<const _CharT*>()(__s, _M_data())
3418  || less<const _CharT*>()(_M_data() + this->size(), __s));
3419  }
3420 
3421  // When __n = 1 way faster than the general multichar
3422  // traits_type::copy/move/assign.
3423  static void
3424  _M_copy(_CharT* __d, const _CharT* __s, size_type __n) _GLIBCXX_NOEXCEPT
3425  {
3426  if (__n == 1)
3427  traits_type::assign(*__d, *__s);
3428  else
3429  traits_type::copy(__d, __s, __n);
3430  }
3431 
3432  static void
3433  _M_move(_CharT* __d, const _CharT* __s, size_type __n) _GLIBCXX_NOEXCEPT
3434  {
3435  if (__n == 1)
3436  traits_type::assign(*__d, *__s);
3437  else
3438  traits_type::move(__d, __s, __n);
3439  }
3440 
3441  static void
3442  _M_assign(_CharT* __d, size_type __n, _CharT __c) _GLIBCXX_NOEXCEPT
3443  {
3444  if (__n == 1)
3445  traits_type::assign(*__d, __c);
3446  else
3447  traits_type::assign(__d, __n, __c);
3448  }
3449 
3450  // _S_copy_chars is a separate template to permit specialization
3451  // to optimize for the common case of pointers as iterators.
3452  template<class _Iterator>
3453  static void
3454  _S_copy_chars(_CharT* __p, _Iterator __k1, _Iterator __k2)
3455  {
3456  for (; __k1 != __k2; ++__k1, (void)++__p)
3457  traits_type::assign(*__p, *__k1); // These types are off.
3458  }
3459 
3460  static void
3461  _S_copy_chars(_CharT* __p, iterator __k1, iterator __k2) _GLIBCXX_NOEXCEPT
3462  { _S_copy_chars(__p, __k1.base(), __k2.base()); }
3463 
3464  static void
3465  _S_copy_chars(_CharT* __p, const_iterator __k1, const_iterator __k2)
3466  _GLIBCXX_NOEXCEPT
3467  { _S_copy_chars(__p, __k1.base(), __k2.base()); }
3468 
3469  static void
3470  _S_copy_chars(_CharT* __p, _CharT* __k1, _CharT* __k2) _GLIBCXX_NOEXCEPT
3471  { _M_copy(__p, __k1, __k2 - __k1); }
3472 
3473  static void
3474  _S_copy_chars(_CharT* __p, const _CharT* __k1, const _CharT* __k2)
3475  _GLIBCXX_NOEXCEPT
3476  { _M_copy(__p, __k1, __k2 - __k1); }
3477 
3478  static int
3479  _S_compare(size_type __n1, size_type __n2) _GLIBCXX_NOEXCEPT
3480  {
3481  const difference_type __d = difference_type(__n1 - __n2);
3482 
3483  if (__d > __gnu_cxx::__numeric_traits<int>::__max)
3484  return __gnu_cxx::__numeric_traits<int>::__max;
3485  else if (__d < __gnu_cxx::__numeric_traits<int>::__min)
3486  return __gnu_cxx::__numeric_traits<int>::__min;
3487  else
3488  return int(__d);
3489  }
3490 
3491  void
3492  _M_mutate(size_type __pos, size_type __len1, size_type __len2);
3493 
3494  void
3495  _M_leak_hard();
3496 
3497  static _Rep&
3498  _S_empty_rep() _GLIBCXX_NOEXCEPT
3499  { return _Rep::_S_empty_rep(); }
3500 
3501 #if __cplusplus >= 201703L
3502  // A helper type for avoiding boiler-plate.
3503  typedef basic_string_view<_CharT, _Traits> __sv_type;
3504 
3505  template<typename _Tp, typename _Res>
3506  using _If_sv = enable_if_t<
3507  __and_<is_convertible<const _Tp&, __sv_type>,
3508  __not_<is_convertible<const _Tp*, const basic_string*>>,
3509  __not_<is_convertible<const _Tp&, const _CharT*>>>::value,
3510  _Res>;
3511 
3512  // Allows an implicit conversion to __sv_type.
3513  static __sv_type
3514  _S_to_string_view(__sv_type __svt) noexcept
3515  { return __svt; }
3516 
3517  // Wraps a string_view by explicit conversion and thus
3518  // allows to add an internal constructor that does not
3519  // participate in overload resolution when a string_view
3520  // is provided.
3521  struct __sv_wrapper
3522  {
3523  explicit __sv_wrapper(__sv_type __sv) noexcept : _M_sv(__sv) { }
3524  __sv_type _M_sv;
3525  };
3526 
3527  /**
3528  * @brief Only internally used: Construct string from a string view
3529  * wrapper.
3530  * @param __svw string view wrapper.
3531  * @param __a Allocator to use.
3532  */
3533  explicit
3534  basic_string(__sv_wrapper __svw, const _Alloc& __a)
3535  : basic_string(__svw._M_sv.data(), __svw._M_sv.size(), __a) { }
3536 #endif
3537 
3538  public:
3539  // Construct/copy/destroy:
3540  // NB: We overload ctors in some cases instead of using default
3541  // arguments, per 17.4.4.4 para. 2 item 2.
3542 
3543  /**
3544  * @brief Default constructor creates an empty string.
3545  */
3546  basic_string()
3547 #if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3548  _GLIBCXX_NOEXCEPT
3549  : _M_dataplus(_S_empty_rep()._M_refdata(), _Alloc())
3550 #else
3551  : _M_dataplus(_S_construct(size_type(), _CharT(), _Alloc()), _Alloc())
3552 #endif
3553  { }
3554 
3555  /**
3556  * @brief Construct an empty string using allocator @a a.
3557  */
3558  explicit
3559  basic_string(const _Alloc& __a);
3560 
3561  // NB: per LWG issue 42, semantics different from IS:
3562  /**
3563  * @brief Construct string with copy of value of @a str.
3564  * @param __str Source string.
3565  */
3566  basic_string(const basic_string& __str);
3567 
3568  // _GLIBCXX_RESOLVE_LIB_DEFECTS
3569  // 2583. no way to supply an allocator for basic_string(str, pos)
3570  /**
3571  * @brief Construct string as copy of a substring.
3572  * @param __str Source string.
3573  * @param __pos Index of first character to copy from.
3574  * @param __a Allocator to use.
3575  */
3576  basic_string(const basic_string& __str, size_type __pos,
3577  const _Alloc& __a = _Alloc());
3578 
3579  /**
3580  * @brief Construct string as copy of a substring.
3581  * @param __str Source string.
3582  * @param __pos Index of first character to copy from.
3583  * @param __n Number of characters to copy.
3584  */
3585  basic_string(const basic_string& __str, size_type __pos,
3586  size_type __n);
3587  /**
3588  * @brief Construct string as copy of a substring.
3589  * @param __str Source string.
3590  * @param __pos Index of first character to copy from.
3591  * @param __n Number of characters to copy.
3592  * @param __a Allocator to use.
3593  */
3594  basic_string(const basic_string& __str, size_type __pos,
3595  size_type __n, const _Alloc& __a);
3596 
3597  /**
3598  * @brief Construct string initialized by a character %array.
3599  * @param __s Source character %array.
3600  * @param __n Number of characters to copy.
3601  * @param __a Allocator to use (default is default allocator).
3602  *
3603  * NB: @a __s must have at least @a __n characters, &apos;\\0&apos;
3604  * has no special meaning.
3605  */
3606  basic_string(const _CharT* __s, size_type __n,
3607  const _Alloc& __a = _Alloc());
3608 
3609  /**
3610  * @brief Construct string as copy of a C string.
3611  * @param __s Source C string.
3612  * @param __a Allocator to use (default is default allocator).
3613  */
3614 #if __cpp_deduction_guides && ! defined _GLIBCXX_DEFINING_STRING_INSTANTIATIONS
3615  // _GLIBCXX_RESOLVE_LIB_DEFECTS
3616  // 3076. basic_string CTAD ambiguity
3617  template<typename = _RequireAllocator<_Alloc>>
3618 #endif
3619  basic_string(const _CharT* __s, const _Alloc& __a = _Alloc())
3620  : _M_dataplus(_S_construct(__s, __s ? __s + traits_type::length(__s) :
3621  __s + npos, __a), __a)
3622  { }
3623 
3624  /**
3625  * @brief Construct string as multiple characters.
3626  * @param __n Number of characters.
3627  * @param __c Character to use.
3628  * @param __a Allocator to use (default is default allocator).
3629  */
3630  basic_string(size_type __n, _CharT __c, const _Alloc& __a = _Alloc());
3631 
3632 #if __cplusplus >= 201103L
3633  /**
3634  * @brief Move construct string.
3635  * @param __str Source string.
3636  *
3637  * The newly-created string contains the exact contents of @a __str.
3638  * @a __str is a valid, but unspecified string.
3639  **/
3640  basic_string(basic_string&& __str)
3641 #if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3642  noexcept // FIXME C++11: should always be noexcept.
3643 #endif
3644  : _M_dataplus(std::move(__str._M_dataplus))
3645  {
3646 #if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3647  __str._M_data(_S_empty_rep()._M_refdata());
3648 #else
3649  __str._M_data(_S_construct(size_type(), _CharT(), get_allocator()));
3650 #endif
3651  }
3652 
3653  /**
3654  * @brief Construct string from an initializer %list.
3655  * @param __l std::initializer_list of characters.
3656  * @param __a Allocator to use (default is default allocator).
3657  */
3658  basic_string(initializer_list<_CharT> __l, const _Alloc& __a = _Alloc());
3659 
3660  basic_string(const basic_string& __str, const _Alloc& __a)
3661  : _M_dataplus(__str._M_rep()->_M_grab(__a, __str.get_allocator()), __a)
3662  { }
3663 
3664  basic_string(basic_string&& __str, const _Alloc& __a)
3665  : _M_dataplus(__str._M_data(), __a)
3666  {
3667  if (__a == __str.get_allocator())
3668  {
3669 #if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3670  __str._M_data(_S_empty_rep()._M_refdata());
3671 #else
3672  __str._M_data(_S_construct(size_type(), _CharT(), __a));
3673 #endif
3674  }
3675  else
3676  _M_dataplus._M_p = _S_construct(__str.begin(), __str.end(), __a);
3677  }
3678 #endif // C++11
3679 
3680  /**
3681  * @brief Construct string as copy of a range.
3682  * @param __beg Start of range.
3683  * @param __end End of range.
3684  * @param __a Allocator to use (default is default allocator).
3685  */
3686  template<class _InputIterator>
3687  basic_string(_InputIterator __beg, _InputIterator __end,
3688  const _Alloc& __a = _Alloc());
3689 
3690 #if __cplusplus >= 201703L
3691  /**
3692  * @brief Construct string from a substring of a string_view.
3693  * @param __t Source object convertible to string view.
3694  * @param __pos The index of the first character to copy from __t.
3695  * @param __n The number of characters to copy from __t.
3696  * @param __a Allocator to use.
3697  */
3698  template<typename _Tp, typename = _If_sv<_Tp, void>>
3699  basic_string(const _Tp& __t, size_type __pos, size_type __n,
3700  const _Alloc& __a = _Alloc())
3701  : basic_string(_S_to_string_view(__t).substr(__pos, __n), __a) { }
3702 
3703  /**
3704  * @brief Construct string from a string_view.
3705  * @param __t Source object convertible to string view.
3706  * @param __a Allocator to use (default is default allocator).
3707  */
3708  template<typename _Tp, typename = _If_sv<_Tp, void>>
3709  explicit
3710  basic_string(const _Tp& __t, const _Alloc& __a = _Alloc())
3711  : basic_string(__sv_wrapper(_S_to_string_view(__t)), __a) { }
3712 #endif // C++17
3713 
3714  /**
3715  * @brief Destroy the string instance.
3716  */
3717  ~basic_string() _GLIBCXX_NOEXCEPT
3718  { _M_rep()->_M_dispose(this->get_allocator()); }
3719 
3720  /**
3721  * @brief Assign the value of @a str to this string.
3722  * @param __str Source string.
3723  */
3724  basic_string&
3725  operator=(const basic_string& __str)
3726  { return this->assign(__str); }
3727 
3728  /**
3729  * @brief Copy contents of @a s into this string.
3730  * @param __s Source null-terminated string.
3731  */
3732  basic_string&
3733  operator=(const _CharT* __s)
3734  { return this->assign(__s); }
3735 
3736  /**
3737  * @brief Set value to string of length 1.
3738  * @param __c Source character.
3739  *
3740  * Assigning to a character makes this string length 1 and
3741  * (*this)[0] == @a c.
3742  */
3743  basic_string&
3744  operator=(_CharT __c)
3745  {
3746  this->assign(1, __c);
3747  return *this;
3748  }
3749 
3750 #if __cplusplus >= 201103L
3751  /**
3752  * @brief Move assign the value of @a str to this string.
3753  * @param __str Source string.
3754  *
3755  * The contents of @a str are moved into this string (without copying).
3756  * @a str is a valid, but unspecified string.
3757  **/
3758  basic_string&
3760  _GLIBCXX_NOEXCEPT_IF(allocator_traits<_Alloc>::is_always_equal::value)
3761  {
3762  // NB: DR 1204.
3763  this->swap(__str);
3764  return *this;
3765  }
3766 
3767  /**
3768  * @brief Set value to string constructed from initializer %list.
3769  * @param __l std::initializer_list.
3770  */
3771  basic_string&
3773  {
3774  this->assign(__l.begin(), __l.size());
3775  return *this;
3776  }
3777 #endif // C++11
3778 
3779 #if __cplusplus >= 201703L
3780  /**
3781  * @brief Set value to string constructed from a string_view.
3782  * @param __svt An object convertible to string_view.
3783  */
3784  template<typename _Tp>
3785  _If_sv<_Tp, basic_string&>
3786  operator=(const _Tp& __svt)
3787  { return this->assign(__svt); }
3788 
3789  /**
3790  * @brief Convert to a string_view.
3791  * @return A string_view.
3792  */
3793  operator __sv_type() const noexcept
3794  { return __sv_type(data(), size()); }
3795 #endif // C++17
3796 
3797  // Iterators:
3798  /**
3799  * Returns a read/write iterator that points to the first character in
3800  * the %string. Unshares the string.
3801  */
3802  iterator
3803  begin() // FIXME C++11: should be noexcept.
3804  {
3805  _M_leak();
3806  return iterator(_M_data());
3807  }
3808 
3809  /**
3810  * Returns a read-only (constant) iterator that points to the first
3811  * character in the %string.
3812  */
3813  const_iterator
3814  begin() const _GLIBCXX_NOEXCEPT
3815  { return const_iterator(_M_data()); }
3816 
3817  /**
3818  * Returns a read/write iterator that points one past the last
3819  * character in the %string. Unshares the string.
3820  */
3821  iterator
3822  end() // FIXME C++11: should be noexcept.
3823  {
3824  _M_leak();
3825  return iterator(_M_data() + this->size());
3826  }
3827 
3828  /**
3829  * Returns a read-only (constant) iterator that points one past the
3830  * last character in the %string.
3831  */
3832  const_iterator
3833  end() const _GLIBCXX_NOEXCEPT
3834  { return const_iterator(_M_data() + this->size()); }
3835 
3836  /**
3837  * Returns a read/write reverse iterator that points to the last
3838  * character in the %string. Iteration is done in reverse element
3839  * order. Unshares the string.
3840  */
3842  rbegin() // FIXME C++11: should be noexcept.
3843  { return reverse_iterator(this->end()); }
3844 
3845  /**
3846  * Returns a read-only (constant) reverse iterator that points
3847  * to the last character in the %string. Iteration is done in
3848  * reverse element order.
3849  */
3850  const_reverse_iterator
3851  rbegin() const _GLIBCXX_NOEXCEPT
3852  { return const_reverse_iterator(this->end()); }
3853 
3854  /**
3855  * Returns a read/write reverse iterator that points to one before the
3856  * first character in the %string. Iteration is done in reverse
3857  * element order. Unshares the string.
3858  */
3860  rend() // FIXME C++11: should be noexcept.
3861  { return reverse_iterator(this->begin()); }
3862 
3863  /**
3864  * Returns a read-only (constant) reverse iterator that points
3865  * to one before the first character in the %string. Iteration
3866  * is done in reverse element order.
3867  */
3868  const_reverse_iterator
3869  rend() const _GLIBCXX_NOEXCEPT
3870  { return const_reverse_iterator(this->begin()); }
3871 
3872 #if __cplusplus >= 201103L
3873  /**
3874  * Returns a read-only (constant) iterator that points to the first
3875  * character in the %string.
3876  */
3877  const_iterator
3879  { return const_iterator(this->_M_data()); }
3880 
3881  /**
3882  * Returns a read-only (constant) iterator that points one past the
3883  * last character in the %string.
3884  */
3885  const_iterator
3886  cend() const noexcept
3887  { return const_iterator(this->_M_data() + this->size()); }
3888 
3889  /**
3890  * Returns a read-only (constant) reverse iterator that points
3891  * to the last character in the %string. Iteration is done in
3892  * reverse element order.
3893  */
3894  const_reverse_iterator
3896  { return const_reverse_iterator(this->end()); }
3897 
3898  /**
3899  * Returns a read-only (constant) reverse iterator that points
3900  * to one before the first character in the %string. Iteration
3901  * is done in reverse element order.
3902  */
3903  const_reverse_iterator
3904  crend() const noexcept
3905  { return const_reverse_iterator(this->begin()); }
3906 #endif
3907 
3908  public:
3909  // Capacity:
3910  /// Returns the number of characters in the string, not including any
3911  /// null-termination.
3912  size_type
3913  size() const _GLIBCXX_NOEXCEPT
3914  { return _M_rep()->_M_length; }
3915 
3916  /// Returns the number of characters in the string, not including any
3917  /// null-termination.
3918  size_type
3919  length() const _GLIBCXX_NOEXCEPT
3920  { return _M_rep()->_M_length; }
3921 
3922  /// Returns the size() of the largest possible %string.
3923  size_type
3924  max_size() const _GLIBCXX_NOEXCEPT
3925  { return _Rep::_S_max_size; }
3926 
3927  /**
3928  * @brief Resizes the %string to the specified number of characters.
3929  * @param __n Number of characters the %string should contain.
3930  * @param __c Character to fill any new elements.
3931  *
3932  * This function will %resize the %string to the specified
3933  * number of characters. If the number is smaller than the
3934  * %string's current size the %string is truncated, otherwise
3935  * the %string is extended and new elements are %set to @a __c.
3936  */
3937  void
3938  resize(size_type __n, _CharT __c);
3939 
3940  /**
3941  * @brief Resizes the %string to the specified number of characters.
3942  * @param __n Number of characters the %string should contain.
3943  *
3944  * This function will resize the %string to the specified length. If
3945  * the new size is smaller than the %string's current size the %string
3946  * is truncated, otherwise the %string is extended and new characters
3947  * are default-constructed. For basic types such as char, this means
3948  * setting them to 0.
3949  */
3950  void
3951  resize(size_type __n)
3952  { this->resize(__n, _CharT()); }
3953 
3954 #if __cplusplus >= 201103L
3955  /// A non-binding request to reduce capacity() to size().
3956  void
3957  shrink_to_fit() _GLIBCXX_NOEXCEPT
3958  {
3959 #if __cpp_exceptions
3960  if (capacity() > size())
3961  {
3962  try
3963  { reserve(0); }
3964  catch(...)
3965  { }
3966  }
3967 #endif
3968  }
3969 #endif
3970 
3971  /**
3972  * Returns the total number of characters that the %string can hold
3973  * before needing to allocate more memory.
3974  */
3975  size_type
3976  capacity() const _GLIBCXX_NOEXCEPT
3977  { return _M_rep()->_M_capacity; }
3978 
3979  /**
3980  * @brief Attempt to preallocate enough memory for specified number of
3981  * characters.
3982  * @param __res_arg Number of characters required.
3983  * @throw std::length_error If @a __res_arg exceeds @c max_size().
3984  *
3985  * This function attempts to reserve enough memory for the
3986  * %string to hold the specified number of characters. If the
3987  * number requested is more than max_size(), length_error is
3988  * thrown.
3989  *
3990  * The advantage of this function is that if optimal code is a
3991  * necessity and the user can determine the string length that will be
3992  * required, the user can reserve the memory in %advance, and thus
3993  * prevent a possible reallocation of memory and copying of %string
3994  * data.
3995  */
3996  void
3997  reserve(size_type __res_arg = 0);
3998 
3999  /**
4000  * Erases the string, making it empty.
4001  */
4002 #if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
4003  void
4004  clear() _GLIBCXX_NOEXCEPT
4005  {
4006  if (_M_rep()->_M_is_shared())
4007  {
4008  _M_rep()->_M_dispose(this->get_allocator());
4009  _M_data(_S_empty_rep()._M_refdata());
4010  }
4011  else
4012  _M_rep()->_M_set_length_and_sharable(0);
4013  }
4014 #else
4015  // PR 56166: this should not throw.
4016  void
4017  clear()
4018  { _M_mutate(0, this->size(), 0); }
4019 #endif
4020 
4021  /**
4022  * Returns true if the %string is empty. Equivalent to
4023  * <code>*this == ""</code>.
4024  */
4025  _GLIBCXX_NODISCARD bool
4026  empty() const _GLIBCXX_NOEXCEPT
4027  { return this->size() == 0; }
4028 
4029  // Element access:
4030  /**
4031  * @brief Subscript access to the data contained in the %string.
4032  * @param __pos The index of the character to access.
4033  * @return Read-only (constant) reference to the character.
4034  *
4035  * This operator allows for easy, array-style, data access.
4036  * Note that data access with this operator is unchecked and
4037  * out_of_range lookups are not defined. (For checked lookups
4038  * see at().)
4039  */
4040  const_reference
4041  operator[] (size_type __pos) const _GLIBCXX_NOEXCEPT
4042  {
4043  __glibcxx_assert(__pos <= size());
4044  return _M_data()[__pos];
4045  }
4046 
4047  /**
4048  * @brief Subscript access to the data contained in the %string.
4049  * @param __pos The index of the character to access.
4050  * @return Read/write reference to the character.
4051  *
4052  * This operator allows for easy, array-style, data access.
4053  * Note that data access with this operator is unchecked and
4054  * out_of_range lookups are not defined. (For checked lookups
4055  * see at().) Unshares the string.
4056  */
4057  reference
4058  operator[](size_type __pos)
4059  {
4060  // Allow pos == size() both in C++98 mode, as v3 extension,
4061  // and in C++11 mode.
4062  __glibcxx_assert(__pos <= size());
4063  // In pedantic mode be strict in C++98 mode.
4064  _GLIBCXX_DEBUG_PEDASSERT(__cplusplus >= 201103L || __pos < size());
4065  _M_leak();
4066  return _M_data()[__pos];
4067  }
4068 
4069  /**
4070  * @brief Provides access to the data contained in the %string.
4071  * @param __n The index of the character to access.
4072  * @return Read-only (const) reference to the character.
4073  * @throw std::out_of_range If @a n is an invalid index.
4074  *
4075  * This function provides for safer data access. The parameter is
4076  * first checked that it is in the range of the string. The function
4077  * throws out_of_range if the check fails.
4078  */
4079  const_reference
4080  at(size_type __n) const
4081  {
4082  if (__n >= this->size())
4083  __throw_out_of_range_fmt(__N("basic_string::at: __n "
4084  "(which is %zu) >= this->size() "
4085  "(which is %zu)"),
4086  __n, this->size());
4087  return _M_data()[__n];
4088  }
4089 
4090  /**
4091  * @brief Provides access to the data contained in the %string.
4092  * @param __n The index of the character to access.
4093  * @return Read/write reference to the character.
4094  * @throw std::out_of_range If @a n is an invalid index.
4095  *
4096  * This function provides for safer data access. The parameter is
4097  * first checked that it is in the range of the string. The function
4098  * throws out_of_range if the check fails. Success results in
4099  * unsharing the string.
4100  */
4101  reference
4102  at(size_type __n)
4103  {
4104  if (__n >= size())
4105  __throw_out_of_range_fmt(__N("basic_string::at: __n "
4106  "(which is %zu) >= this->size() "
4107  "(which is %zu)"),
4108  __n, this->size());
4109  _M_leak();
4110  return _M_data()[__n];
4111  }
4112 
4113 #if __cplusplus >= 201103L
4114  /**
4115  * Returns a read/write reference to the data at the first
4116  * element of the %string.
4117  */
4118  reference
4120  {
4121  __glibcxx_assert(!empty());
4122  return operator[](0);
4123  }
4124 
4125  /**
4126  * Returns a read-only (constant) reference to the data at the first
4127  * element of the %string.
4128  */
4129  const_reference
4130  front() const noexcept
4131  {
4132  __glibcxx_assert(!empty());
4133  return operator[](0);
4134  }
4135 
4136  /**
4137  * Returns a read/write reference to the data at the last
4138  * element of the %string.
4139  */
4140  reference
4142  {
4143  __glibcxx_assert(!empty());
4144  return operator[](this->size() - 1);
4145  }
4146 
4147  /**
4148  * Returns a read-only (constant) reference to the data at the
4149  * last element of the %string.
4150  */
4151  const_reference
4152  back() const noexcept
4153  {
4154  __glibcxx_assert(!empty());
4155  return operator[](this->size() - 1);
4156  }
4157 #endif
4158 
4159  // Modifiers:
4160  /**
4161  * @brief Append a string to this string.
4162  * @param __str The string to append.
4163  * @return Reference to this string.
4164  */
4165  basic_string&
4166  operator+=(const basic_string& __str)
4167  { return this->append(__str); }
4168 
4169  /**
4170  * @brief Append a C string.
4171  * @param __s The C string to append.
4172  * @return Reference to this string.
4173  */
4174  basic_string&
4175  operator+=(const _CharT* __s)
4176  { return this->append(__s); }
4177 
4178  /**
4179  * @brief Append a character.
4180  * @param __c The character to append.
4181  * @return Reference to this string.
4182  */
4183  basic_string&
4184  operator+=(_CharT __c)
4185  {
4186  this->push_back(__c);
4187  return *this;
4188  }
4189 
4190 #if __cplusplus >= 201103L
4191  /**
4192  * @brief Append an initializer_list of characters.
4193  * @param __l The initializer_list of characters to be appended.
4194  * @return Reference to this string.
4195  */
4196  basic_string&
4198  { return this->append(__l.begin(), __l.size()); }
4199 #endif // C++11
4200 
4201 #if __cplusplus >= 201703L
4202  /**
4203  * @brief Append a string_view.
4204  * @param __svt The object convertible to string_view to be appended.
4205  * @return Reference to this string.
4206  */
4207  template<typename _Tp>
4208  _If_sv<_Tp, basic_string&>
4209  operator+=(const _Tp& __svt)
4210  { return this->append(__svt); }
4211 #endif // C++17
4212 
4213  /**
4214  * @brief Append a string to this string.
4215  * @param __str The string to append.
4216  * @return Reference to this string.
4217  */
4218  basic_string&
4219  append(const basic_string& __str);
4220 
4221  /**
4222  * @brief Append a substring.
4223  * @param __str The string to append.
4224  * @param __pos Index of the first character of str to append.
4225  * @param __n The number of characters to append.
4226  * @return Reference to this string.
4227  * @throw std::out_of_range if @a __pos is not a valid index.
4228  *
4229  * This function appends @a __n characters from @a __str
4230  * starting at @a __pos to this string. If @a __n is is larger
4231  * than the number of available characters in @a __str, the
4232  * remainder of @a __str is appended.
4233  */
4234  basic_string&
4235  append(const basic_string& __str, size_type __pos, size_type __n = npos);
4236 
4237  /**
4238  * @brief Append a C substring.
4239  * @param __s The C string to append.
4240  * @param __n The number of characters to append.
4241  * @return Reference to this string.
4242  */
4243  basic_string&
4244  append(const _CharT* __s, size_type __n);
4245 
4246  /**
4247  * @brief Append a C string.
4248  * @param __s The C string to append.
4249  * @return Reference to this string.
4250  */
4251  basic_string&
4252  append(const _CharT* __s)
4253  {
4254  __glibcxx_requires_string(__s);
4255  return this->append(__s, traits_type::length(__s));
4256  }
4257 
4258  /**
4259  * @brief Append multiple characters.
4260  * @param __n The number of characters to append.
4261  * @param __c The character to use.
4262  * @return Reference to this string.
4263  *
4264  * Appends __n copies of __c to this string.
4265  */
4266  basic_string&
4267  append(size_type __n, _CharT __c);
4268 
4269 #if __cplusplus >= 201103L
4270  /**
4271  * @brief Append an initializer_list of characters.
4272  * @param __l The initializer_list of characters to append.
4273  * @return Reference to this string.
4274  */
4275  basic_string&
4277  { return this->append(__l.begin(), __l.size()); }
4278 #endif // C++11
4279 
4280  /**
4281  * @brief Append a range of characters.
4282  * @param __first Iterator referencing the first character to append.
4283  * @param __last Iterator marking the end of the range.
4284  * @return Reference to this string.
4285  *
4286  * Appends characters in the range [__first,__last) to this string.
4287  */
4288  template<class _InputIterator>
4289  basic_string&
4290  append(_InputIterator __first, _InputIterator __last)
4291  { return this->replace(_M_iend(), _M_iend(), __first, __last); }
4292 
4293 #if __cplusplus >= 201703L
4294  /**
4295  * @brief Append a string_view.
4296  * @param __svt The object convertible to string_view to be appended.
4297  * @return Reference to this string.
4298  */
4299  template<typename _Tp>
4300  _If_sv<_Tp, basic_string&>
4301  append(const _Tp& __svt)
4302  {
4303  __sv_type __sv = __svt;
4304  return this->append(__sv.data(), __sv.size());
4305  }
4306 
4307  /**
4308  * @brief Append a range of characters from a string_view.
4309  * @param __svt The object convertible to string_view to be appended
4310  * from.
4311  * @param __pos The position in the string_view to append from.
4312  * @param __n The number of characters to append from the string_view.
4313  * @return Reference to this string.
4314  */
4315  template<typename _Tp>
4316  _If_sv<_Tp, basic_string&>
4317  append(const _Tp& __svt, size_type __pos, size_type __n = npos)
4318  {
4319  __sv_type __sv = __svt;
4320  return append(__sv.data()
4321  + std::__sv_check(__sv.size(), __pos, "basic_string::append"),
4322  std::__sv_limit(__sv.size(), __pos, __n));
4323  }
4324 #endif // C++17
4325 
4326  /**
4327  * @brief Append a single character.
4328  * @param __c Character to append.
4329  */
4330  void
4331  push_back(_CharT __c)
4332  {
4333  const size_type __len = 1 + this->size();
4334  if (__len > this->capacity() || _M_rep()->_M_is_shared())
4335  this->reserve(__len);
4336  traits_type::assign(_M_data()[this->size()], __c);
4337  _M_rep()->_M_set_length_and_sharable(__len);
4338  }
4339 
4340  /**
4341  * @brief Set value to contents of another string.
4342  * @param __str Source string to use.
4343  * @return Reference to this string.
4344  */
4345  basic_string&
4346  assign(const basic_string& __str);
4347 
4348 #if __cplusplus >= 201103L
4349  /**
4350  * @brief Set value to contents of another string.
4351  * @param __str Source string to use.
4352  * @return Reference to this string.
4353  *
4354  * This function sets this string to the exact contents of @a __str.
4355  * @a __str is a valid, but unspecified string.
4356  */
4357  basic_string&
4358  assign(basic_string&& __str)
4359  noexcept(allocator_traits<_Alloc>::is_always_equal::value)
4360  {
4361  this->swap(__str);
4362  return *this;
4363  }
4364 #endif // C++11
4365 
4366  /**
4367  * @brief Set value to a substring of a string.
4368  * @param __str The string to use.
4369  * @param __pos Index of the first character of str.
4370  * @param __n Number of characters to use.
4371  * @return Reference to this string.
4372  * @throw std::out_of_range if @a pos is not a valid index.
4373  *
4374  * This function sets this string to the substring of @a __str
4375  * consisting of @a __n characters at @a __pos. If @a __n is
4376  * is larger than the number of available characters in @a
4377  * __str, the remainder of @a __str is used.
4378  */
4379  basic_string&
4380  assign(const basic_string& __str, size_type __pos, size_type __n = npos)
4381  { return this->assign(__str._M_data()
4382  + __str._M_check(__pos, "basic_string::assign"),
4383  __str._M_limit(__pos, __n)); }
4384 
4385  /**
4386  * @brief Set value to a C substring.
4387  * @param __s The C string to use.
4388  * @param __n Number of characters to use.
4389  * @return Reference to this string.
4390  *
4391  * This function sets the value of this string to the first @a __n
4392  * characters of @a __s. If @a __n is is larger than the number of
4393  * available characters in @a __s, the remainder of @a __s is used.
4394  */
4395  basic_string&
4396  assign(const _CharT* __s, size_type __n);
4397 
4398  /**
4399  * @brief Set value to contents of a C string.
4400  * @param __s The C string to use.
4401  * @return Reference to this string.
4402  *
4403  * This function sets the value of this string to the value of @a __s.
4404  * The data is copied, so there is no dependence on @a __s once the
4405  * function returns.
4406  */
4407  basic_string&
4408  assign(const _CharT* __s)
4409  {
4410  __glibcxx_requires_string(__s);
4411  return this->assign(__s, traits_type::length(__s));
4412  }
4413 
4414  /**
4415  * @brief Set value to multiple characters.
4416  * @param __n Length of the resulting string.
4417  * @param __c The character to use.
4418  * @return Reference to this string.
4419  *
4420  * This function sets the value of this string to @a __n copies of
4421  * character @a __c.
4422  */
4423  basic_string&
4424  assign(size_type __n, _CharT __c)
4425  { return _M_replace_aux(size_type(0), this->size(), __n, __c); }
4426 
4427  /**
4428  * @brief Set value to a range of characters.
4429  * @param __first Iterator referencing the first character to append.
4430  * @param __last Iterator marking the end of the range.
4431  * @return Reference to this string.
4432  *
4433  * Sets value of string to characters in the range [__first,__last).
4434  */
4435  template<class _InputIterator>
4436  basic_string&
4437  assign(_InputIterator __first, _InputIterator __last)
4438  { return this->replace(_M_ibegin(), _M_iend(), __first, __last); }
4439 
4440 #if __cplusplus >= 201103L
4441  /**
4442  * @brief Set value to an initializer_list of characters.
4443  * @param __l The initializer_list of characters to assign.
4444  * @return Reference to this string.
4445  */
4446  basic_string&
4448  { return this->assign(__l.begin(), __l.size()); }
4449 #endif // C++11
4450 
4451 #if __cplusplus >= 201703L
4452  /**
4453  * @brief Set value from a string_view.
4454  * @param __svt The source object convertible to string_view.
4455  * @return Reference to this string.
4456  */
4457  template<typename _Tp>
4458  _If_sv<_Tp, basic_string&>
4459  assign(const _Tp& __svt)
4460  {
4461  __sv_type __sv = __svt;
4462  return this->assign(__sv.data(), __sv.size());
4463  }
4464 
4465  /**
4466  * @brief Set value from a range of characters in a string_view.
4467  * @param __svt The source object convertible to string_view.
4468  * @param __pos The position in the string_view to assign from.
4469  * @param __n The number of characters to assign.
4470  * @return Reference to this string.
4471  */
4472  template<typename _Tp>
4473  _If_sv<_Tp, basic_string&>
4474  assign(const _Tp& __svt, size_type __pos, size_type __n = npos)
4475  {
4476  __sv_type __sv = __svt;
4477  return assign(__sv.data()
4478  + std::__sv_check(__sv.size(), __pos, "basic_string::assign"),
4479  std::__sv_limit(__sv.size(), __pos, __n));
4480  }
4481 #endif // C++17
4482 
4483  /**
4484  * @brief Insert multiple characters.
4485  * @param __p Iterator referencing location in string to insert at.
4486  * @param __n Number of characters to insert
4487  * @param __c The character to insert.
4488  * @throw std::length_error If new length exceeds @c max_size().
4489  *
4490  * Inserts @a __n copies of character @a __c starting at the
4491  * position referenced by iterator @a __p. If adding
4492  * characters causes the length to exceed max_size(),
4493  * length_error is thrown. The value of the string doesn't
4494  * change if an error is thrown.
4495  */
4496  void
4497  insert(iterator __p, size_type __n, _CharT __c)
4498  { this->replace(__p, __p, __n, __c); }
4499 
4500  /**
4501  * @brief Insert a range of characters.
4502  * @param __p Iterator referencing location in string to insert at.
4503  * @param __beg Start of range.
4504  * @param __end End of range.
4505  * @throw std::length_error If new length exceeds @c max_size().
4506  *
4507  * Inserts characters in range [__beg,__end). If adding
4508  * characters causes the length to exceed max_size(),
4509  * length_error is thrown. The value of the string doesn't
4510  * change if an error is thrown.
4511  */
4512  template<class _InputIterator>
4513  void
4514  insert(iterator __p, _InputIterator __beg, _InputIterator __end)
4515  { this->replace(__p, __p, __beg, __end); }
4516 
4517 #if __cplusplus >= 201103L
4518  /**
4519  * @brief Insert an initializer_list of characters.
4520  * @param __p Iterator referencing location in string to insert at.
4521  * @param __l The initializer_list of characters to insert.
4522  * @throw std::length_error If new length exceeds @c max_size().
4523  */
4524  void
4526  {
4527  _GLIBCXX_DEBUG_PEDASSERT(__p >= _M_ibegin() && __p <= _M_iend());
4528  this->insert(__p - _M_ibegin(), __l.begin(), __l.size());
4529  }
4530 #endif // C++11
4531 
4532  /**
4533  * @brief Insert value of a string.
4534  * @param __pos1 Position in string to insert at.
4535  * @param __str The string to insert.
4536  * @return Reference to this string.
4537  * @throw std::length_error If new length exceeds @c max_size().
4538  *
4539  * Inserts value of @a __str starting at @a __pos1. If adding
4540  * characters causes the length to exceed max_size(),
4541  * length_error is thrown. The value of the string doesn't
4542  * change if an error is thrown.
4543  */
4544  basic_string&
4545  insert(size_type __pos1, const basic_string& __str)
4546  { return this->insert(__pos1, __str, size_type(0), __str.size()); }
4547 
4548  /**
4549  * @brief Insert a substring.
4550  * @param __pos1 Position in string to insert at.
4551  * @param __str The string to insert.
4552  * @param __pos2 Start of characters in str to insert.
4553  * @param __n Number of characters to insert.
4554  * @return Reference to this string.
4555  * @throw std::length_error If new length exceeds @c max_size().
4556  * @throw std::out_of_range If @a pos1 > size() or
4557  * @a __pos2 > @a str.size().
4558  *
4559  * Starting at @a pos1, insert @a __n character of @a __str
4560  * beginning with @a __pos2. If adding characters causes the
4561  * length to exceed max_size(), length_error is thrown. If @a
4562  * __pos1 is beyond the end of this string or @a __pos2 is
4563  * beyond the end of @a __str, out_of_range is thrown. The
4564  * value of the string doesn't change if an error is thrown.
4565  */
4566  basic_string&
4567  insert(size_type __pos1, const basic_string& __str,
4568  size_type __pos2, size_type __n = npos)
4569  { return this->insert(__pos1, __str._M_data()
4570  + __str._M_check(__pos2, "basic_string::insert"),
4571  __str._M_limit(__pos2, __n)); }
4572 
4573  /**
4574  * @brief Insert a C substring.
4575  * @param __pos Position in string to insert at.
4576  * @param __s The C string to insert.
4577  * @param __n The number of characters to insert.
4578  * @return Reference to this string.
4579  * @throw std::length_error If new length exceeds @c max_size().
4580  * @throw std::out_of_range If @a __pos is beyond the end of this
4581  * string.
4582  *
4583  * Inserts the first @a __n characters of @a __s starting at @a
4584  * __pos. If adding characters causes the length to exceed
4585  * max_size(), length_error is thrown. If @a __pos is beyond
4586  * end(), out_of_range is thrown. The value of the string
4587  * doesn't change if an error is thrown.
4588  */
4589  basic_string&
4590  insert(size_type __pos, const _CharT* __s, size_type __n);
4591 
4592  /**
4593  * @brief Insert a C string.
4594  * @param __pos Position in string to insert at.
4595  * @param __s The C string to insert.
4596  * @return Reference to this string.
4597  * @throw std::length_error If new length exceeds @c max_size().
4598  * @throw std::out_of_range If @a pos is beyond the end of this
4599  * string.
4600  *
4601  * Inserts the first @a n characters of @a __s starting at @a __pos. If
4602  * adding characters causes the length to exceed max_size(),
4603  * length_error is thrown. If @a __pos is beyond end(), out_of_range is
4604  * thrown. The value of the string doesn't change if an error is
4605  * thrown.
4606  */
4607  basic_string&
4608  insert(size_type __pos, const _CharT* __s)
4609  {
4610  __glibcxx_requires_string(__s);
4611  return this->insert(__pos, __s, traits_type::length(__s));
4612  }
4613 
4614  /**
4615  * @brief Insert multiple characters.
4616  * @param __pos Index in string to insert at.
4617  * @param __n Number of characters to insert
4618  * @param __c The character to insert.
4619  * @return Reference to this string.
4620  * @throw std::length_error If new length exceeds @c max_size().
4621  * @throw std::out_of_range If @a __pos is beyond the end of this
4622  * string.
4623  *
4624  * Inserts @a __n copies of character @a __c starting at index
4625  * @a __pos. If adding characters causes the length to exceed
4626  * max_size(), length_error is thrown. If @a __pos > length(),
4627  * out_of_range is thrown. The value of the string doesn't
4628  * change if an error is thrown.
4629  */
4630  basic_string&
4631  insert(size_type __pos, size_type __n, _CharT __c)
4632  { return _M_replace_aux(_M_check(__pos, "basic_string::insert"),
4633  size_type(0), __n, __c); }
4634 
4635  /**
4636  * @brief Insert one character.
4637  * @param __p Iterator referencing position in string to insert at.
4638  * @param __c The character to insert.
4639  * @return Iterator referencing newly inserted char.
4640  * @throw std::length_error If new length exceeds @c max_size().
4641  *
4642  * Inserts character @a __c at position referenced by @a __p.
4643  * If adding character causes the length to exceed max_size(),
4644  * length_error is thrown. If @a __p is beyond end of string,
4645  * out_of_range is thrown. The value of the string doesn't
4646  * change if an error is thrown.
4647  */
4648  iterator
4649  insert(iterator __p, _CharT __c)
4650  {
4651  _GLIBCXX_DEBUG_PEDASSERT(__p >= _M_ibegin() && __p <= _M_iend());
4652  const size_type __pos = __p - _M_ibegin();
4653  _M_replace_aux(__pos, size_type(0), size_type(1), __c);
4654  _M_rep()->_M_set_leaked();
4655  return iterator(_M_data() + __pos);
4656  }
4657 
4658 #if __cplusplus >= 201703L
4659  /**
4660  * @brief Insert a string_view.
4661  * @param __pos Position in string to insert at.
4662  * @param __svt The object convertible to string_view to insert.
4663  * @return Reference to this string.
4664  */
4665  template<typename _Tp>
4666  _If_sv<_Tp, basic_string&>
4667  insert(size_type __pos, const _Tp& __svt)
4668  {
4669  __sv_type __sv = __svt;
4670  return this->insert(__pos, __sv.data(), __sv.size());
4671  }
4672 
4673  /**
4674  * @brief Insert a string_view.
4675  * @param __pos Position in string to insert at.
4676  * @param __svt The object convertible to string_view to insert from.
4677  * @param __pos Position in string_view to insert
4678  * from.
4679  * @param __n The number of characters to insert.
4680  * @return Reference to this string.
4681  */
4682  template<typename _Tp>
4683  _If_sv<_Tp, basic_string&>
4684  insert(size_type __pos1, const _Tp& __svt,
4685  size_type __pos2, size_type __n = npos)
4686  {
4687  __sv_type __sv = __svt;
4688  return this->replace(__pos1, size_type(0), __sv.data()
4689  + std::__sv_check(__sv.size(), __pos2, "basic_string::insert"),
4690  std::__sv_limit(__sv.size(), __pos2, __n));
4691  }
4692 #endif // C++17
4693 
4694  /**
4695  * @brief Remove characters.
4696  * @param __pos Index of first character to remove (default 0).
4697  * @param __n Number of characters to remove (default remainder).
4698  * @return Reference to this string.
4699  * @throw std::out_of_range If @a pos is beyond the end of this
4700  * string.
4701  *
4702  * Removes @a __n characters from this string starting at @a
4703  * __pos. The length of the string is reduced by @a __n. If
4704  * there are < @a __n characters to remove, the remainder of
4705  * the string is truncated. If @a __p is beyond end of string,
4706  * out_of_range is thrown. The value of the string doesn't
4707  * change if an error is thrown.
4708  */
4709  basic_string&
4710  erase(size_type __pos = 0, size_type __n = npos)
4711  {
4712  _M_mutate(_M_check(__pos, "basic_string::erase"),
4713  _M_limit(__pos, __n), size_type(0));
4714  return *this;
4715  }
4716 
4717  /**
4718  * @brief Remove one character.
4719  * @param __position Iterator referencing the character to remove.
4720  * @return iterator referencing same location after removal.
4721  *
4722  * Removes the character at @a __position from this string. The value
4723  * of the string doesn't change if an error is thrown.
4724  */
4725  iterator
4726  erase(iterator __position)
4727  {
4728  _GLIBCXX_DEBUG_PEDASSERT(__position >= _M_ibegin()
4729  && __position < _M_iend());
4730  const size_type __pos = __position - _M_ibegin();
4731  _M_mutate(__pos, size_type(1), size_type(0));
4732  _M_rep()->_M_set_leaked();
4733  return iterator(_M_data() + __pos);
4734  }
4735 
4736  /**
4737  * @brief Remove a range of characters.
4738  * @param __first Iterator referencing the first character to remove.
4739  * @param __last Iterator referencing the end of the range.
4740  * @return Iterator referencing location of first after removal.
4741  *
4742  * Removes the characters in the range [first,last) from this string.
4743  * The value of the string doesn't change if an error is thrown.
4744  */
4745  iterator
4746  erase(iterator __first, iterator __last);
4747 
4748 #if __cplusplus >= 201103L
4749  /**
4750  * @brief Remove the last character.
4751  *
4752  * The string must be non-empty.
4753  */
4754  void
4755  pop_back() // FIXME C++11: should be noexcept.
4756  {
4757  __glibcxx_assert(!empty());
4758  erase(size() - 1, 1);
4759  }
4760 #endif // C++11
4761 
4762  /**
4763  * @brief Replace characters with value from another string.
4764  * @param __pos Index of first character to replace.
4765  * @param __n Number of characters to be replaced.
4766  * @param __str String to insert.
4767  * @return Reference to this string.
4768  * @throw std::out_of_range If @a pos is beyond the end of this
4769  * string.
4770  * @throw std::length_error If new length exceeds @c max_size().
4771  *
4772  * Removes the characters in the range [__pos,__pos+__n) from
4773  * this string. In place, the value of @a __str is inserted.
4774  * If @a __pos is beyond end of string, out_of_range is thrown.
4775  * If the length of the result exceeds max_size(), length_error
4776  * is thrown. The value of the string doesn't change if an
4777  * error is thrown.
4778  */
4779  basic_string&
4780  replace(size_type __pos, size_type __n, const basic_string& __str)
4781  { return this->replace(__pos, __n, __str._M_data(), __str.size()); }
4782 
4783  /**
4784  * @brief Replace characters with value from another string.
4785  * @param __pos1 Index of first character to replace.
4786  * @param __n1 Number of characters to be replaced.
4787  * @param __str String to insert.
4788  * @param __pos2 Index of first character of str to use.
4789  * @param __n2 Number of characters from str to use.
4790  * @return Reference to this string.
4791  * @throw std::out_of_range If @a __pos1 > size() or @a __pos2 >
4792  * __str.size().
4793  * @throw std::length_error If new length exceeds @c max_size().
4794  *
4795  * Removes the characters in the range [__pos1,__pos1 + n) from this
4796  * string. In place, the value of @a __str is inserted. If @a __pos is
4797  * beyond end of string, out_of_range is thrown. If the length of the
4798  * result exceeds max_size(), length_error is thrown. The value of the
4799  * string doesn't change if an error is thrown.
4800  */
4801  basic_string&
4802  replace(size_type __pos1, size_type __n1, const basic_string& __str,
4803  size_type __pos2, size_type __n2 = npos)
4804  { return this->replace(__pos1, __n1, __str._M_data()
4805  + __str._M_check(__pos2, "basic_string::replace"),
4806  __str._M_limit(__pos2, __n2)); }
4807 
4808  /**
4809  * @brief Replace characters with value of a C substring.
4810  * @param __pos Index of first character to replace.
4811  * @param __n1 Number of characters to be replaced.
4812  * @param __s C string to insert.
4813  * @param __n2 Number of characters from @a s to use.
4814  * @return Reference to this string.
4815  * @throw std::out_of_range If @a pos1 > size().
4816  * @throw std::length_error If new length exceeds @c max_size().
4817  *
4818  * Removes the characters in the range [__pos,__pos + __n1)
4819  * from this string. In place, the first @a __n2 characters of
4820  * @a __s are inserted, or all of @a __s if @a __n2 is too large. If
4821  * @a __pos is beyond end of string, out_of_range is thrown. If
4822  * the length of result exceeds max_size(), length_error is
4823  * thrown. The value of the string doesn't change if an error
4824  * is thrown.
4825  */
4826  basic_string&
4827  replace(size_type __pos, size_type __n1, const _CharT* __s,
4828  size_type __n2);
4829 
4830  /**
4831  * @brief Replace characters with value of a C string.
4832  * @param __pos Index of first character to replace.
4833  * @param __n1 Number of characters to be replaced.
4834  * @param __s C string to insert.
4835  * @return Reference to this string.
4836  * @throw std::out_of_range If @a pos > size().
4837  * @throw std::length_error If new length exceeds @c max_size().
4838  *
4839  * Removes the characters in the range [__pos,__pos + __n1)
4840  * from this string. In place, the characters of @a __s are
4841  * inserted. If @a __pos is beyond end of string, out_of_range
4842  * is thrown. If the length of result exceeds max_size(),
4843  * length_error is thrown. The value of the string doesn't
4844  * change if an error is thrown.
4845  */
4846  basic_string&
4847  replace(size_type __pos, size_type __n1, const _CharT* __s)
4848  {
4849  __glibcxx_requires_string(__s);
4850  return this->replace(__pos, __n1, __s, traits_type::length(__s));
4851  }
4852 
4853  /**
4854  * @brief Replace characters with multiple characters.
4855  * @param __pos Index of first character to replace.
4856  * @param __n1 Number of characters to be replaced.
4857  * @param __n2 Number of characters to insert.
4858  * @param __c Character to insert.
4859  * @return Reference to this string.
4860  * @throw std::out_of_range If @a __pos > size().
4861  * @throw std::length_error If new length exceeds @c max_size().
4862  *
4863  * Removes the characters in the range [pos,pos + n1) from this
4864  * string. In place, @a __n2 copies of @a __c are inserted.
4865  * If @a __pos is beyond end of string, out_of_range is thrown.
4866  * If the length of result exceeds max_size(), length_error is
4867  * thrown. The value of the string doesn't change if an error
4868  * is thrown.
4869  */
4870  basic_string&
4871  replace(size_type __pos, size_type __n1, size_type __n2, _CharT __c)
4872  { return _M_replace_aux(_M_check(__pos, "basic_string::replace"),
4873  _M_limit(__pos, __n1), __n2, __c); }
4874 
4875  /**
4876  * @brief Replace range of characters with string.
4877  * @param __i1 Iterator referencing start of range to replace.
4878  * @param __i2 Iterator referencing end of range to replace.
4879  * @param __str String value to insert.
4880  * @return Reference to this string.
4881  * @throw std::length_error If new length exceeds @c max_size().
4882  *
4883  * Removes the characters in the range [__i1,__i2). In place,
4884  * the value of @a __str is inserted. If the length of result
4885  * exceeds max_size(), length_error is thrown. The value of
4886  * the string doesn't change if an error is thrown.
4887  */
4888  basic_string&
4889  replace(iterator __i1, iterator __i2, const basic_string& __str)
4890  { return this->replace(__i1, __i2, __str._M_data(), __str.size()); }
4891 
4892  /**
4893  * @brief Replace range of characters with C substring.
4894  * @param __i1 Iterator referencing start of range to replace.
4895  * @param __i2 Iterator referencing end of range to replace.
4896  * @param __s C string value to insert.
4897  * @param __n Number of characters from s to insert.
4898  * @return Reference to this string.
4899  * @throw std::length_error If new length exceeds @c max_size().
4900  *
4901  * Removes the characters in the range [__i1,__i2). In place,
4902  * the first @a __n characters of @a __s are inserted. If the
4903  * length of result exceeds max_size(), length_error is thrown.
4904  * The value of the string doesn't change if an error is
4905  * thrown.
4906  */
4907  basic_string&
4908  replace(iterator __i1, iterator __i2, const _CharT* __s, size_type __n)
4909  {
4910  _GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
4911  && __i2 <= _M_iend());
4912  return this->replace(__i1 - _M_ibegin(), __i2 - __i1, __s, __n);
4913  }
4914 
4915  /**
4916  * @brief Replace range of characters with C string.
4917  * @param __i1 Iterator referencing start of range to replace.
4918  * @param __i2 Iterator referencing end of range to replace.
4919  * @param __s C string value to insert.
4920  * @return Reference to this string.
4921  * @throw std::length_error If new length exceeds @c max_size().
4922  *
4923  * Removes the characters in the range [__i1,__i2). In place,
4924  * the characters of @a __s are inserted. If the length of
4925  * result exceeds max_size(), length_error is thrown. The
4926  * value of the string doesn't change if an error is thrown.
4927  */
4928  basic_string&
4929  replace(iterator __i1, iterator __i2, const _CharT* __s)
4930  {
4931  __glibcxx_requires_string(__s);
4932  return this->replace(__i1, __i2, __s, traits_type::length(__s));
4933  }
4934 
4935  /**
4936  * @brief Replace range of characters with multiple characters
4937  * @param __i1 Iterator referencing start of range to replace.
4938  * @param __i2 Iterator referencing end of range to replace.
4939  * @param __n Number of characters to insert.
4940  * @param __c Character to insert.
4941  * @return Reference to this string.
4942  * @throw std::length_error If new length exceeds @c max_size().
4943  *
4944  * Removes the characters in the range [__i1,__i2). In place,
4945  * @a __n copies of @a __c are inserted. If the length of
4946  * result exceeds max_size(), length_error is thrown. The
4947  * value of the string doesn't change if an error is thrown.
4948  */
4949  basic_string&
4950  replace(iterator __i1, iterator __i2, size_type __n, _CharT __c)
4951  {
4952  _GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
4953  && __i2 <= _M_iend());
4954  return _M_replace_aux(__i1 - _M_ibegin(), __i2 - __i1, __n, __c);
4955  }
4956 
4957  /**
4958  * @brief Replace range of characters with range.
4959  * @param __i1 Iterator referencing start of range to replace.
4960  * @param __i2 Iterator referencing end of range to replace.
4961  * @param __k1 Iterator referencing start of range to insert.
4962  * @param __k2 Iterator referencing end of range to insert.
4963  * @return Reference to this string.
4964  * @throw std::length_error If new length exceeds @c max_size().
4965  *
4966  * Removes the characters in the range [__i1,__i2). In place,
4967  * characters in the range [__k1,__k2) are inserted. If the
4968  * length of result exceeds max_size(), length_error is thrown.
4969  * The value of the string doesn't change if an error is
4970  * thrown.
4971  */
4972  template<class _InputIterator>
4973  basic_string&
4974  replace(iterator __i1, iterator __i2,
4975  _InputIterator __k1, _InputIterator __k2)
4976  {
4977  _GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
4978  && __i2 <= _M_iend());
4979  __glibcxx_requires_valid_range(__k1, __k2);
4980  typedef typename std::__is_integer<_InputIterator>::__type _Integral;
4981  return _M_replace_dispatch(__i1, __i2, __k1, __k2, _Integral());
4982  }
4983 
4984  // Specializations for the common case of pointer and iterator:
4985  // useful to avoid the overhead of temporary buffering in _M_replace.
4986  basic_string&
4987  replace(iterator __i1, iterator __i2, _CharT* __k1, _CharT* __k2)
4988  {
4989  _GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
4990  && __i2 <= _M_iend());
4991  __glibcxx_requires_valid_range(__k1, __k2);
4992  return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
4993  __k1, __k2 - __k1);
4994  }
4995 
4996  basic_string&
4997  replace(iterator __i1, iterator __i2,
4998  const _CharT* __k1, const _CharT* __k2)
4999  {
5000  _GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
5001  && __i2 <= _M_iend());
5002  __glibcxx_requires_valid_range(__k1, __k2);
5003  return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
5004  __k1, __k2 - __k1);
5005  }
5006 
5007  basic_string&
5008  replace(iterator __i1, iterator __i2, iterator __k1, iterator __k2)
5009  {
5010  _GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
5011  && __i2 <= _M_iend());
5012  __glibcxx_requires_valid_range(__k1, __k2);
5013  return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
5014  __k1.base(), __k2 - __k1);
5015  }
5016 
5017  basic_string&
5018  replace(iterator __i1, iterator __i2,
5019  const_iterator __k1, const_iterator __k2)
5020  {
5021  _GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
5022  && __i2 <= _M_iend());
5023  __glibcxx_requires_valid_range(__k1, __k2);
5024  return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
5025  __k1.base(), __k2 - __k1);
5026  }
5027 
5028 #if __cplusplus >= 201103L
5029  /**
5030  * @brief Replace range of characters with initializer_list.
5031  * @param __i1 Iterator referencing start of range to replace.
5032  * @param __i2 Iterator referencing end of range to replace.
5033  * @param __l The initializer_list of characters to insert.
5034  * @return Reference to this string.
5035  * @throw std::length_error If new length exceeds @c max_size().
5036  *
5037  * Removes the characters in the range [__i1,__i2). In place,
5038  * characters in the range [__k1,__k2) are inserted. If the
5039  * length of result exceeds max_size(), length_error is thrown.
5040  * The value of the string doesn't change if an error is
5041  * thrown.
5042  */
5043  basic_string& replace(iterator __i1, iterator __i2,
5045  { return this->replace(__i1, __i2, __l.begin(), __l.end()); }
5046 #endif // C++11
5047 
5048 #if __cplusplus >= 201703L
5049  /**
5050  * @brief Replace range of characters with string_view.
5051  * @param __pos The position to replace at.
5052  * @param __n The number of characters to replace.
5053  * @param __svt The object convertible to string_view to insert.
5054  * @return Reference to this string.
5055  */
5056  template<typename _Tp>
5057  _If_sv<_Tp, basic_string&>
5058  replace(size_type __pos, size_type __n, const _Tp& __svt)
5059  {
5060  __sv_type __sv = __svt;
5061  return this->replace(__pos, __n, __sv.data(), __sv.size());
5062  }
5063 
5064  /**
5065  * @brief Replace range of characters with string_view.
5066  * @param __pos1 The position to replace at.
5067  * @param __n1 The number of characters to replace.
5068  * @param __svt The object convertible to string_view to insert from.
5069  * @param __pos2 The position in the string_view to insert from.
5070  * @param __n2 The number of characters to insert.
5071  * @return Reference to this string.
5072  */
5073  template<typename _Tp>
5074  _If_sv<_Tp, basic_string&>
5075  replace(size_type __pos1, size_type __n1, const _Tp& __svt,
5076  size_type __pos2, size_type __n2 = npos)
5077  {
5078  __sv_type __sv = __svt;
5079  return this->replace(__pos1, __n1,
5080  __sv.data()
5081  + std::__sv_check(__sv.size(), __pos2, "basic_string::replace"),
5082  std::__sv_limit(__sv.size(), __pos2, __n2));
5083  }
5084 
5085  /**
5086  * @brief Replace range of characters with string_view.
5087  * @param __i1 An iterator referencing the start position
5088  to replace at.
5089  * @param __i2 An iterator referencing the end position
5090  for the replace.
5091  * @param __svt The object convertible to string_view to insert from.
5092  * @return Reference to this string.
5093  */
5094  template<typename _Tp>
5095  _If_sv<_Tp, basic_string&>
5096  replace(const_iterator __i1, const_iterator __i2, const _Tp& __svt)
5097  {
5098  __sv_type __sv = __svt;
5099  return this->replace(__i1 - begin(), __i2 - __i1, __sv);
5100  }
5101 #endif // C++17
5102 
5103  private:
5104  template<class _Integer>
5105  basic_string&
5106  _M_replace_dispatch(iterator __i1, iterator __i2, _Integer __n,
5107  _Integer __val, __true_type)
5108  { return _M_replace_aux(__i1 - _M_ibegin(), __i2 - __i1, __n, __val); }
5109 
5110  template<class _InputIterator>
5111  basic_string&
5112  _M_replace_dispatch(iterator __i1, iterator __i2, _InputIterator __k1,
5113  _InputIterator __k2, __false_type);
5114 
5115  basic_string&
5116  _M_replace_aux(size_type __pos1, size_type __n1, size_type __n2,
5117  _CharT __c);
5118 
5119  basic_string&
5120  _M_replace_safe(size_type __pos1, size_type __n1, const _CharT* __s,
5121  size_type __n2);
5122 
5123  // _S_construct_aux is used to implement the 21.3.1 para 15 which
5124  // requires special behaviour if _InIter is an integral type
5125  template<class _InIterator>
5126  static _CharT*
5127  _S_construct_aux(_InIterator __beg, _InIterator __end,
5128  const _Alloc& __a, __false_type)
5129  {
5130  typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
5131  return _S_construct(__beg, __end, __a, _Tag());
5132  }
5133 
5134  // _GLIBCXX_RESOLVE_LIB_DEFECTS
5135  // 438. Ambiguity in the "do the right thing" clause
5136  template<class _Integer>
5137  static _CharT*
5138  _S_construct_aux(_Integer __beg, _Integer __end,
5139  const _Alloc& __a, __true_type)
5140  { return _S_construct_aux_2(static_cast<size_type>(__beg),
5141  __end, __a); }
5142 
5143  static _CharT*
5144  _S_construct_aux_2(size_type __req, _CharT __c, const _Alloc& __a)
5145  { return _S_construct(__req, __c, __a); }
5146 
5147  template<class _InIterator>
5148  static _CharT*
5149  _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a)
5150  {
5151  typedef typename std::__is_integer<_InIterator>::__type _Integral;
5152  return _S_construct_aux(__beg, __end, __a, _Integral());
5153  }
5154 
5155  // For Input Iterators, used in istreambuf_iterators, etc.
5156  template<class _InIterator>
5157  static _CharT*
5158  _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a,
5159  input_iterator_tag);
5160 
5161  // For forward_iterators up to random_access_iterators, used for
5162  // string::iterator, _CharT*, etc.
5163  template<class _FwdIterator>
5164  static _CharT*
5165  _S_construct(_FwdIterator __beg, _FwdIterator __end, const _Alloc& __a,
5166  forward_iterator_tag);
5167 
5168  static _CharT*
5169  _S_construct(size_type __req, _CharT __c, const _Alloc& __a);
5170 
5171  public:
5172 
5173  /**
5174  * @brief Copy substring into C string.
5175  * @param __s C string to copy value into.
5176  * @param __n Number of characters to copy.
5177  * @param __pos Index of first character to copy.
5178  * @return Number of characters actually copied
5179  * @throw std::out_of_range If __pos > size().
5180  *
5181  * Copies up to @a __n characters starting at @a __pos into the
5182  * C string @a __s. If @a __pos is %greater than size(),
5183  * out_of_range is thrown.
5184  */
5185  size_type
5186  copy(_CharT* __s, size_type __n, size_type __pos = 0) const;
5187 
5188  /**
5189  * @brief Swap contents with another string.
5190  * @param __s String to swap with.
5191  *
5192  * Exchanges the contents of this string with that of @a __s in constant
5193  * time.
5194  */
5195  void
5196  swap(basic_string& __s)
5197  _GLIBCXX_NOEXCEPT_IF(allocator_traits<_Alloc>::is_always_equal::value);
5198 
5199  // String operations:
5200  /**
5201  * @brief Return const pointer to null-terminated contents.
5202  *
5203  * This is a handle to internal data. Do not modify or dire things may
5204  * happen.
5205  */
5206  const _CharT*
5207  c_str() const _GLIBCXX_NOEXCEPT
5208  { return _M_data(); }
5209 
5210  /**
5211  * @brief Return const pointer to contents.
5212  *
5213  * This is a pointer to internal data. It is undefined to modify
5214  * the contents through the returned pointer. To get a pointer that
5215  * allows modifying the contents use @c &str[0] instead,
5216  * (or in C++17 the non-const @c str.data() overload).
5217  */
5218  const _CharT*
5219  data() const _GLIBCXX_NOEXCEPT
5220  { return _M_data(); }
5221 
5222 #if __cplusplus >= 201703L
5223  /**
5224  * @brief Return non-const pointer to contents.
5225  *
5226  * This is a pointer to the character sequence held by the string.
5227  * Modifying the characters in the sequence is allowed.
5228  */
5229  _CharT*
5230  data() noexcept
5231  {
5232  _M_leak();
5233  return _M_data();
5234  }
5235 #endif
5236 
5237  /**
5238  * @brief Return copy of allocator used to construct this string.
5239  */
5240  allocator_type
5241  get_allocator() const _GLIBCXX_NOEXCEPT
5242  { return _M_dataplus; }
5243 
5244  /**
5245  * @brief Find position of a C substring.
5246  * @param __s C string to locate.
5247  * @param __pos Index of character to search from.
5248  * @param __n Number of characters from @a s to search for.
5249  * @return Index of start of first occurrence.
5250  *
5251  * Starting from @a __pos, searches forward for the first @a
5252  * __n characters in @a __s within this string. If found,
5253  * returns the index where it begins. If not found, returns
5254  * npos.
5255  */
5256  size_type
5257  find(const _CharT* __s, size_type __pos, size_type __n) const
5258  _GLIBCXX_NOEXCEPT;
5259 
5260  /**
5261  * @brief Find position of a string.
5262  * @param __str String to locate.
5263  * @param __pos Index of character to search from (default 0).
5264  * @return Index of start of first occurrence.
5265  *
5266  * Starting from @a __pos, searches forward for value of @a __str within
5267  * this string. If found, returns the index where it begins. If not
5268  * found, returns npos.
5269  */
5270  size_type
5271  find(const basic_string& __str, size_type __pos = 0) const
5272  _GLIBCXX_NOEXCEPT
5273  { return this->find(__str.data(), __pos, __str.size()); }
5274 
5275  /**
5276  * @brief Find position of a C string.
5277  * @param __s C string to locate.
5278  * @param __pos Index of character to search from (default 0).
5279  * @return Index of start of first occurrence.
5280  *
5281  * Starting from @a __pos, searches forward for the value of @a
5282  * __s within this string. If found, returns the index where
5283  * it begins. If not found, returns npos.
5284  */
5285  size_type
5286  find(const _CharT* __s, size_type __pos = 0) const _GLIBCXX_NOEXCEPT
5287  {
5288  __glibcxx_requires_string(__s);
5289  return this->find(__s, __pos, traits_type::length(__s));
5290  }
5291 
5292  /**
5293  * @brief Find position of a character.
5294  * @param __c Character to locate.
5295  * @param __pos Index of character to search from (default 0).
5296  * @return Index of first occurrence.
5297  *
5298  * Starting from @a __pos, searches forward for @a __c within
5299  * this string. If found, returns the index where it was
5300  * found. If not found, returns npos.
5301  */
5302  size_type
5303  find(_CharT __c, size_type __pos = 0) const _GLIBCXX_NOEXCEPT;
5304 
5305 #if __cplusplus >= 201703L
5306  /**
5307  * @brief Find position of a string_view.
5308  * @param __svt The object convertible to string_view to locate.
5309  * @param __pos Index of character to search from (default 0).
5310  * @return Index of start of first occurrence.
5311  */
5312  template<typename _Tp>
5313  _If_sv<_Tp, size_type>
5314  find(const _Tp& __svt, size_type __pos = 0) const
5315  noexcept(is_same<_Tp, __sv_type>::value)
5316  {
5317  __sv_type __sv = __svt;
5318  return this->find(__sv.data(), __pos, __sv.size());
5319  }
5320 #endif // C++17
5321 
5322  /**
5323  * @brief Find last position of a string.
5324  * @param __str String to locate.
5325  * @param __pos Index of character to search back from (default end).
5326  * @return Index of start of last occurrence.
5327  *
5328  * Starting from @a __pos, searches backward for value of @a
5329  * __str within this string. If found, returns the index where
5330  * it begins. If not found, returns npos.
5331  */
5332  size_type
5333  rfind(const basic_string& __str, size_type __pos = npos) const
5334  _GLIBCXX_NOEXCEPT
5335  { return this->rfind(__str.data(), __pos, __str.size()); }
5336 
5337  /**
5338  * @brief Find last position of a C substring.
5339  * @param __s C string to locate.
5340  * @param __pos Index of character to search back from.
5341  * @param __n Number of characters from s to search for.
5342  * @return Index of start of last occurrence.
5343  *
5344  * Starting from @a __pos, searches backward for the first @a
5345  * __n characters in @a __s within this string. If found,
5346  * returns the index where it begins. If not found, returns
5347  * npos.
5348  */
5349  size_type
5350  rfind(const _CharT* __s, size_type __pos, size_type __n) const
5351  _GLIBCXX_NOEXCEPT;
5352 
5353  /**
5354  * @brief Find last position of a C string.
5355  * @param __s C string to locate.
5356  * @param __pos Index of character to start search at (default end).
5357  * @return Index of start of last occurrence.
5358  *
5359  * Starting from @a __pos, searches backward for the value of
5360  * @a __s within this string. If found, returns the index
5361  * where it begins. If not found, returns npos.
5362  */
5363  size_type
5364  rfind(const _CharT* __s, size_type __pos = npos) const _GLIBCXX_NOEXCEPT
5365  {
5366  __glibcxx_requires_string(__s);
5367  return this->rfind(__s, __pos, traits_type::length(__s));
5368  }
5369 
5370  /**
5371  * @brief Find last position of a character.
5372  * @param __c Character to locate.
5373  * @param __pos Index of character to search back from (default end).
5374  * @return Index of last occurrence.
5375  *
5376  * Starting from @a __pos, searches backward for @a __c within
5377  * this string. If found, returns the index where it was
5378  * found. If not found, returns npos.
5379  */
5380  size_type
5381  rfind(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT;
5382 
5383 #if __cplusplus >= 201703L
5384  /**
5385  * @brief Find last position of a string_view.
5386  * @param __svt The object convertible to string_view to locate.
5387  * @param __pos Index of character to search back from (default end).
5388  * @return Index of start of last occurrence.
5389  */
5390  template<typename _Tp>
5391  _If_sv<_Tp, size_type>
5392  rfind(const _Tp& __svt, size_type __pos = npos) const
5393  noexcept(is_same<_Tp, __sv_type>::value)
5394  {
5395  __sv_type __sv = __svt;
5396  return this->rfind(__sv.data(), __pos, __sv.size());
5397  }
5398 #endif // C++17
5399 
5400  /**
5401  * @brief Find position of a character of string.
5402  * @param __str String containing characters to locate.
5403  * @param __pos Index of character to search from (default 0).
5404  * @return Index of first occurrence.
5405  *
5406  * Starting from @a __pos, searches forward for one of the
5407  * characters of @a __str within this string. If found,
5408  * returns the index where it was found. If not found, returns
5409  * npos.
5410  */
5411  size_type
5412  find_first_of(const basic_string& __str, size_type __pos = 0) const
5413  _GLIBCXX_NOEXCEPT
5414  { return this->find_first_of(__str.data(), __pos, __str.size()); }
5415 
5416  /**
5417  * @brief Find position of a character of C substring.
5418  * @param __s String containing characters to locate.
5419  * @param __pos Index of character to search from.
5420  * @param __n Number of characters from s to search for.
5421  * @return Index of first occurrence.
5422  *
5423  * Starting from @a __pos, searches forward for one of the
5424  * first @a __n characters of @a __s within this string. If
5425  * found, returns the index where it was found. If not found,
5426  * returns npos.
5427  */
5428  size_type
5429  find_first_of(const _CharT* __s, size_type __pos, size_type __n) const
5430  _GLIBCXX_NOEXCEPT;
5431 
5432  /**
5433  * @brief Find position of a character of C string.
5434  * @param __s String containing characters to locate.
5435  * @param __pos Index of character to search from (default 0).
5436  * @return Index of first occurrence.
5437  *
5438  * Starting from @a __pos, searches forward for one of the
5439  * characters of @a __s within this string. If found, returns
5440  * the index where it was found. If not found, returns npos.
5441  */
5442  size_type
5443  find_first_of(const _CharT* __s, size_type __pos = 0) const
5444  _GLIBCXX_NOEXCEPT
5445  {
5446  __glibcxx_requires_string(__s);
5447  return this->find_first_of(__s, __pos, traits_type::length(__s));
5448  }
5449 
5450  /**
5451  * @brief Find position of a character.
5452  * @param __c Character to locate.
5453  * @param __pos Index of character to search from (default 0).
5454  * @return Index of first occurrence.
5455  *
5456  * Starting from @a __pos, searches forward for the character
5457  * @a __c within this string. If found, returns the index
5458  * where it was found. If not found, returns npos.
5459  *
5460  * Note: equivalent to find(__c, __pos).
5461  */
5462  size_type
5463  find_first_of(_CharT __c, size_type __pos = 0) const _GLIBCXX_NOEXCEPT
5464  { return this->find(__c, __pos); }
5465 
5466 #if __cplusplus >= 201703L
5467  /**
5468  * @brief Find position of a character of a string_view.
5469  * @param __svt An object convertible to string_view containing
5470  * characters to locate.
5471  * @param __pos Index of character to search from (default 0).
5472  * @return Index of first occurrence.
5473  */
5474  template<typename _Tp>
5475  _If_sv<_Tp, size_type>
5476  find_first_of(const _Tp& __svt, size_type __pos = 0) const
5477  noexcept(is_same<_Tp, __sv_type>::value)
5478  {
5479  __sv_type __sv = __svt;
5480  return this->find_first_of(__sv.data(), __pos, __sv.size());
5481  }
5482 #endif // C++17
5483 
5484  /**
5485  * @brief Find last position of a character of string.
5486  * @param __str String containing characters to locate.
5487  * @param __pos Index of character to search back from (default end).
5488  * @return Index of last occurrence.
5489  *
5490  * Starting from @a __pos, searches backward for one of the
5491  * characters of @a __str within this string. If found,
5492  * returns the index where it was found. If not found, returns
5493  * npos.
5494  */
5495  size_type
5496  find_last_of(const basic_string& __str, size_type __pos = npos) const
5497  _GLIBCXX_NOEXCEPT
5498  { return this->find_last_of(__str.data(), __pos, __str.size()); }
5499 
5500  /**
5501  * @brief Find last position of a character of C substring.
5502  * @param __s C string containing characters to locate.
5503  * @param __pos Index of character to search back from.
5504  * @param __n Number of characters from s to search for.
5505  * @return Index of last occurrence.
5506  *
5507  * Starting from @a __pos, searches backward for one of the
5508  * first @a __n characters of @a __s within this string. If
5509  * found, returns the index where it was found. If not found,
5510  * returns npos.
5511  */
5512  size_type
5513  find_last_of(const _CharT* __s, size_type __pos, size_type __n) const
5514  _GLIBCXX_NOEXCEPT;
5515 
5516  /**
5517  * @brief Find last position of a character of C string.
5518  * @param __s C string containing characters to locate.
5519  * @param __pos Index of character to search back from (default end).
5520  * @return Index of last occurrence.
5521  *
5522  * Starting from @a __pos, searches backward for one of the
5523  * characters of @a __s within this string. If found, returns
5524  * the index where it was found. If not found, returns npos.
5525  */
5526  size_type
5527  find_last_of(const _CharT* __s, size_type __pos = npos) const
5528  _GLIBCXX_NOEXCEPT
5529  {
5530  __glibcxx_requires_string(__s);
5531  return this->find_last_of(__s, __pos, traits_type::length(__s));
5532  }
5533 
5534  /**
5535  * @brief Find last position of a character.
5536  * @param __c Character to locate.
5537  * @param __pos Index of character to search back from (default end).
5538  * @return Index of last occurrence.
5539  *
5540  * Starting from @a __pos, searches backward for @a __c within
5541  * this string. If found, returns the index where it was
5542  * found. If not found, returns npos.
5543  *
5544  * Note: equivalent to rfind(__c, __pos).
5545  */
5546  size_type
5547  find_last_of(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT
5548  { return this->rfind(__c, __pos); }
5549 
5550 #if __cplusplus >= 201703L
5551  /**
5552  * @brief Find last position of a character of string.
5553  * @param __svt An object convertible to string_view containing
5554  * characters to locate.
5555  * @param __pos Index of character to search back from (default end).
5556  * @return Index of last occurrence.
5557  */
5558  template<typename _Tp>
5559  _If_sv<_Tp, size_type>
5560  find_last_of(const _Tp& __svt, size_type __pos = npos) const
5561  noexcept(is_same<_Tp, __sv_type>::value)
5562  {
5563  __sv_type __sv = __svt;
5564  return this->find_last_of(__sv.data(), __pos, __sv.size());
5565  }
5566 #endif // C++17
5567 
5568  /**
5569  * @brief Find position of a character not in string.
5570  * @param __str String containing characters to avoid.
5571  * @param __pos Index of character to search from (default 0).
5572  * @return Index of first occurrence.
5573  *
5574  * Starting from @a __pos, searches forward for a character not contained
5575  * in @a __str within this string. If found, returns the index where it
5576  * was found. If not found, returns npos.
5577  */
5578  size_type
5579  find_first_not_of(const basic_string& __str, size_type __pos = 0) const
5580  _GLIBCXX_NOEXCEPT
5581  { return this->find_first_not_of(__str.data(), __pos, __str.size()); }
5582 
5583  /**
5584  * @brief Find position of a character not in C substring.
5585  * @param __s C string containing characters to avoid.
5586  * @param __pos Index of character to search from.
5587  * @param __n Number of characters from __s to consider.
5588  * @return Index of first occurrence.
5589  *
5590  * Starting from @a __pos, searches forward for a character not
5591  * contained in the first @a __n characters of @a __s within
5592  * this string. If found, returns the index where it was
5593  * found. If not found, returns npos.
5594  */
5595  size_type
5596  find_first_not_of(const _CharT* __s, size_type __pos,
5597  size_type __n) const _GLIBCXX_NOEXCEPT;
5598 
5599  /**
5600  * @brief Find position of a character not in C string.
5601  * @param __s C string containing characters to avoid.
5602  * @param __pos Index of character to search from (default 0).
5603  * @return Index of first occurrence.
5604  *
5605  * Starting from @a __pos, searches forward for a character not
5606  * contained in @a __s within this string. If found, returns
5607  * the index where it was found. If not found, returns npos.
5608  */
5609  size_type
5610  find_first_not_of(const _CharT* __s, size_type __pos = 0) const
5611  _GLIBCXX_NOEXCEPT
5612  {
5613  __glibcxx_requires_string(__s);
5614  return this->find_first_not_of(__s, __pos, traits_type::length(__s));
5615  }
5616 
5617  /**
5618  * @brief Find position of a different character.
5619  * @param __c Character to avoid.
5620  * @param __pos Index of character to search from (default 0).
5621  * @return Index of first occurrence.
5622  *
5623  * Starting from @a __pos, searches forward for a character
5624  * other than @a __c within this string. If found, returns the
5625  * index where it was found. If not found, returns npos.
5626  */
5627  size_type
5628  find_first_not_of(_CharT __c, size_type __pos = 0) const
5629  _GLIBCXX_NOEXCEPT;
5630 
5631 #if __cplusplus >= 201703L
5632  /**
5633  * @brief Find position of a character not in a string_view.
5634  * @param __svt An object convertible to string_view containing
5635  * characters to avoid.
5636  * @param __pos Index of character to search from (default 0).
5637  * @return Index of first occurrence.
5638  */
5639  template<typename _Tp>
5640  _If_sv<_Tp, size_type>
5641  find_first_not_of(const _Tp& __svt, size_type __pos = 0) const
5642  noexcept(is_same<_Tp, __sv_type>::value)
5643  {
5644  __sv_type __sv = __svt;
5645  return this->find_first_not_of(__sv.data(), __pos, __sv.size());
5646  }
5647 #endif // C++17
5648 
5649  /**
5650  * @brief Find last position of a character not in string.
5651  * @param __str String containing characters to avoid.
5652  * @param __pos Index of character to search back from (default end).
5653  * @return Index of last occurrence.
5654  *
5655  * Starting from @a __pos, searches backward for a character
5656  * not contained in @a __str within this string. If found,
5657  * returns the index where it was found. If not found, returns
5658  * npos.
5659  */
5660  size_type
5661  find_last_not_of(const basic_string& __str, size_type __pos = npos) const
5662  _GLIBCXX_NOEXCEPT
5663  { return this->find_last_not_of(__str.data(), __pos, __str.size()); }
5664 
5665  /**
5666  * @brief Find last position of a character not in C substring.
5667  * @param __s C string containing characters to avoid.
5668  * @param __pos Index of character to search back from.
5669  * @param __n Number of characters from s to consider.
5670  * @return Index of last occurrence.
5671  *
5672  * Starting from @a __pos, searches backward for a character not
5673  * contained in the first @a __n characters of @a __s within this string.
5674  * If found, returns the index where it was found. If not found,
5675  * returns npos.
5676  */
5677  size_type
5678  find_last_not_of(const _CharT* __s, size_type __pos,
5679  size_type __n) const _GLIBCXX_NOEXCEPT;
5680  /**
5681  * @brief Find last position of a character not in C string.
5682  * @param __s C string containing characters to avoid.
5683  * @param __pos Index of character to search back from (default end).
5684  * @return Index of last occurrence.
5685  *
5686  * Starting from @a __pos, searches backward for a character
5687  * not contained in @a __s within this string. If found,
5688  * returns the index where it was found. If not found, returns
5689  * npos.
5690  */
5691  size_type
5692  find_last_not_of(const _CharT* __s, size_type __pos = npos) const
5693  _GLIBCXX_NOEXCEPT
5694  {
5695  __glibcxx_requires_string(__s);
5696  return this->find_last_not_of(__s, __pos, traits_type::length(__s));
5697  }
5698 
5699  /**
5700  * @brief Find last position of a different character.
5701  * @param __c Character to avoid.
5702  * @param __pos Index of character to search back from (default end).
5703  * @return Index of last occurrence.
5704  *
5705  * Starting from @a __pos, searches backward for a character other than
5706  * @a __c within this string. If found, returns the index where it was
5707  * found. If not found, returns npos.
5708  */
5709  size_type
5710  find_last_not_of(_CharT __c, size_type __pos = npos) const
5711  _GLIBCXX_NOEXCEPT;
5712 
5713 #if __cplusplus >= 201703L
5714  /**
5715  * @brief Find last position of a character not in a string_view.
5716  * @param __svt An object convertible to string_view containing
5717  * characters to avoid.
5718  * @param __pos Index of character to search back from (default end).
5719  * @return Index of last occurrence.
5720  */
5721  template<typename _Tp>
5722  _If_sv<_Tp, size_type>
5723  find_last_not_of(const _Tp& __svt, size_type __pos = npos) const
5724  noexcept(is_same<_Tp, __sv_type>::value)
5725  {
5726  __sv_type __sv = __svt;
5727  return this->find_last_not_of(__sv.data(), __pos, __sv.size());
5728  }
5729 #endif // C++17
5730 
5731  /**
5732  * @brief Get a substring.
5733  * @param __pos Index of first character (default 0).
5734  * @param __n Number of characters in substring (default remainder).
5735  * @return The new string.
5736  * @throw std::out_of_range If __pos > size().
5737  *
5738  * Construct and return a new string using the @a __n
5739  * characters starting at @a __pos. If the string is too
5740  * short, use the remainder of the characters. If @a __pos is
5741  * beyond the end of the string, out_of_range is thrown.
5742  */
5743  basic_string
5744  substr(size_type __pos = 0, size_type __n = npos) const
5745  { return basic_string(*this,
5746  _M_check(__pos, "basic_string::substr"), __n); }
5747 
5748  /**
5749  * @brief Compare to a string.
5750  * @param __str String to compare against.
5751  * @return Integer < 0, 0, or > 0.
5752  *
5753  * Returns an integer < 0 if this string is ordered before @a
5754  * __str, 0 if their values are equivalent, or > 0 if this
5755  * string is ordered after @a __str. Determines the effective
5756  * length rlen of the strings to compare as the smallest of
5757  * size() and str.size(). The function then compares the two
5758  * strings by calling traits::compare(data(), str.data(),rlen).
5759  * If the result of the comparison is nonzero returns it,
5760  * otherwise the shorter one is ordered first.
5761  */
5762  int
5763  compare(const basic_string& __str) const
5764  {
5765  const size_type __size = this->size();
5766  const size_type __osize = __str.size();
5767  const size_type __len = std::min(__size, __osize);
5768 
5769  int __r = traits_type::compare(_M_data(), __str.data(), __len);
5770  if (!__r)
5771  __r = _S_compare(__size, __osize);
5772  return __r;
5773  }
5774 
5775 #if __cplusplus >= 201703L
5776  /**
5777  * @brief Compare to a string_view.
5778  * @param __svt An object convertible to string_view to compare against.
5779  * @return Integer < 0, 0, or > 0.
5780  */
5781  template<typename _Tp>
5782  _If_sv<_Tp, int>
5783  compare(const _Tp& __svt) const
5785  {
5786  __sv_type __sv = __svt;
5787  const size_type __size = this->size();
5788  const size_type __osize = __sv.size();
5789  const size_type __len = std::min(__size, __osize);
5790 
5791  int __r = traits_type::compare(_M_data(), __sv.data(), __len);
5792  if (!__r)
5793  __r = _S_compare(__size, __osize);
5794  return __r;
5795  }
5796 
5797  /**
5798  * @brief Compare to a string_view.
5799  * @param __pos A position in the string to start comparing from.
5800  * @param __n The number of characters to compare.
5801  * @param __svt An object convertible to string_view to compare
5802  * against.
5803  * @return Integer < 0, 0, or > 0.
5804  */
5805  template<typename _Tp>
5806  _If_sv<_Tp, int>
5807  compare(size_type __pos, size_type __n, const _Tp& __svt) const
5808  noexcept(is_same<_Tp, __sv_type>::value)
5809  {
5810  __sv_type __sv = __svt;
5811  return __sv_type(*this).substr(__pos, __n).compare(__sv);
5812  }
5813 
5814  /**
5815  * @brief Compare to a string_view.
5816  * @param __pos1 A position in the string to start comparing from.
5817  * @param __n1 The number of characters to compare.
5818  * @param __svt An object convertible to string_view to compare
5819  * against.
5820  * @param __pos2 A position in the string_view to start comparing from.
5821  * @param __n2 The number of characters to compare.
5822  * @return Integer < 0, 0, or > 0.
5823  */
5824  template<typename _Tp>
5825  _If_sv<_Tp, int>
5826  compare(size_type __pos1, size_type __n1, const _Tp& __svt,
5827  size_type __pos2, size_type __n2 = npos) const
5828  noexcept(is_same<_Tp, __sv_type>::value)
5829  {
5830  __sv_type __sv = __svt;
5831  return __sv_type(*this)
5832  .substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
5833  }
5834 #endif // C++17
5835 
5836  /**
5837  * @brief Compare substring to a string.
5838  * @param __pos Index of first character of substring.
5839  * @param __n Number of characters in substring.
5840  * @param __str String to compare against.
5841  * @return Integer < 0, 0, or > 0.
5842  *
5843  * Form the substring of this string from the @a __n characters
5844  * starting at @a __pos. Returns an integer < 0 if the
5845  * substring is ordered before @a __str, 0 if their values are
5846  * equivalent, or > 0 if the substring is ordered after @a
5847  * __str. Determines the effective length rlen of the strings
5848  * to compare as the smallest of the length of the substring
5849  * and @a __str.size(). The function then compares the two
5850  * strings by calling
5851  * traits::compare(substring.data(),str.data(),rlen). If the
5852  * result of the comparison is nonzero returns it, otherwise
5853  * the shorter one is ordered first.
5854  */
5855  int
5856  compare(size_type __pos, size_type __n, const basic_string& __str) const;
5857 
5858  /**
5859  * @brief Compare substring to a substring.
5860  * @param __pos1 Index of first character of substring.
5861  * @param __n1 Number of characters in substring.
5862  * @param __str String to compare against.
5863  * @param __pos2 Index of first character of substring of str.
5864  * @param __n2 Number of characters in substring of str.
5865  * @return Integer < 0, 0, or > 0.
5866  *
5867  * Form the substring of this string from the @a __n1
5868  * characters starting at @a __pos1. Form the substring of @a
5869  * __str from the @a __n2 characters starting at @a __pos2.
5870  * Returns an integer < 0 if this substring is ordered before
5871  * the substring of @a __str, 0 if their values are equivalent,
5872  * or > 0 if this substring is ordered after the substring of
5873  * @a __str. Determines the effective length rlen of the
5874  * strings to compare as the smallest of the lengths of the
5875  * substrings. The function then compares the two strings by
5876  * calling
5877  * traits::compare(substring.data(),str.substr(pos2,n2).data(),rlen).
5878  * If the result of the comparison is nonzero returns it,
5879  * otherwise the shorter one is ordered first.
5880  */
5881  int
5882  compare(size_type __pos1, size_type __n1, const basic_string& __str,
5883  size_type __pos2, size_type __n2 = npos) const;
5884 
5885  /**
5886  * @brief Compare to a C string.
5887  * @param __s C string to compare against.
5888  * @return Integer < 0, 0, or > 0.
5889  *
5890  * Returns an integer < 0 if this string is ordered before @a __s, 0 if
5891  * their values are equivalent, or > 0 if this string is ordered after
5892  * @a __s. Determines the effective length rlen of the strings to
5893  * compare as the smallest of size() and the length of a string
5894  * constructed from @a __s. The function then compares the two strings
5895  * by calling traits::compare(data(),s,rlen). If the result of the
5896  * comparison is nonzero returns it, otherwise the shorter one is
5897  * ordered first.
5898  */
5899  int
5900  compare(const _CharT* __s) const _GLIBCXX_NOEXCEPT;
5901 
5902  // _GLIBCXX_RESOLVE_LIB_DEFECTS
5903  // 5 String::compare specification questionable
5904  /**
5905  * @brief Compare substring to a C string.
5906  * @param __pos Index of first character of substring.
5907  * @param __n1 Number of characters in substring.
5908  * @param __s C string to compare against.
5909  * @return Integer < 0, 0, or > 0.
5910  *
5911  * Form the substring of this string from the @a __n1
5912  * characters starting at @a pos. Returns an integer < 0 if
5913  * the substring is ordered before @a __s, 0 if their values
5914  * are equivalent, or > 0 if the substring is ordered after @a
5915  * __s. Determines the effective length rlen of the strings to
5916  * compare as the smallest of the length of the substring and
5917  * the length of a string constructed from @a __s. The
5918  * function then compares the two string by calling
5919  * traits::compare(substring.data(),__s,rlen). If the result of
5920  * the comparison is nonzero returns it, otherwise the shorter
5921  * one is ordered first.
5922  */
5923  int
5924  compare(size_type __pos, size_type __n1, const _CharT* __s) const;
5925 
5926  /**
5927  * @brief Compare substring against a character %array.
5928  * @param __pos Index of first character of substring.
5929  * @param __n1 Number of characters in substring.
5930  * @param __s character %array to compare against.
5931  * @param __n2 Number of characters of s.
5932  * @return Integer < 0, 0, or > 0.
5933  *
5934  * Form the substring of this string from the @a __n1
5935  * characters starting at @a __pos. Form a string from the
5936  * first @a __n2 characters of @a __s. Returns an integer < 0
5937  * if this substring is ordered before the string from @a __s,
5938  * 0 if their values are equivalent, or > 0 if this substring
5939  * is ordered after the string from @a __s. Determines the
5940  * effective length rlen of the strings to compare as the
5941  * smallest of the length of the substring and @a __n2. The
5942  * function then compares the two strings by calling
5943  * traits::compare(substring.data(),s,rlen). If the result of
5944  * the comparison is nonzero returns it, otherwise the shorter
5945  * one is ordered first.
5946  *
5947  * NB: s must have at least n2 characters, &apos;\\0&apos; has
5948  * no special meaning.
5949  */
5950  int
5951  compare(size_type __pos, size_type __n1, const _CharT* __s,
5952  size_type __n2) const;
5953 
5954 #if __cplusplus > 201703L
5955  bool
5956  starts_with(basic_string_view<_CharT, _Traits> __x) const noexcept
5957  { return __sv_type(this->data(), this->size()).starts_with(__x); }
5958 
5959  bool
5960  starts_with(_CharT __x) const noexcept
5961  { return __sv_type(this->data(), this->size()).starts_with(__x); }
5962 
5963  bool
5964  starts_with(const _CharT* __x) const noexcept
5965  { return __sv_type(this->data(), this->size()).starts_with(__x); }
5966 
5967  bool
5968  ends_with(basic_string_view<_CharT, _Traits> __x) const noexcept
5969  { return __sv_type(this->data(), this->size()).ends_with(__x); }
5970 
5971  bool
5972  ends_with(_CharT __x) const noexcept
5973  { return __sv_type(this->data(), this->size()).ends_with(__x); }
5974 
5975  bool
5976  ends_with(const _CharT* __x) const noexcept
5977  { return __sv_type(this->data(), this->size()).ends_with(__x); }
5978 #endif // C++20
5979 
5980 # ifdef _GLIBCXX_TM_TS_INTERNAL
5981  friend void
5982  ::_txnal_cow_string_C1_for_exceptions(void* that, const char* s,
5983  void* exc);
5984  friend const char*
5985  ::_txnal_cow_string_c_str(const void *that);
5986  friend void
5987  ::_txnal_cow_string_D1(void *that);
5988  friend void
5989  ::_txnal_cow_string_D1_commit(void *that);
5990 # endif
5991  };
5992 #endif // !_GLIBCXX_USE_CXX11_ABI
5993 
5994 #if __cpp_deduction_guides >= 201606
5995 _GLIBCXX_BEGIN_NAMESPACE_CXX11
5996  template<typename _InputIterator, typename _CharT
5997  = typename iterator_traits<_InputIterator>::value_type,
5998  typename _Allocator = allocator<_CharT>,
5999  typename = _RequireInputIter<_InputIterator>,
6000  typename = _RequireAllocator<_Allocator>>
6001  basic_string(_InputIterator, _InputIterator, _Allocator = _Allocator())
6002  -> basic_string<_CharT, char_traits<_CharT>, _Allocator>;
6003 
6004  // _GLIBCXX_RESOLVE_LIB_DEFECTS
6005  // 3075. basic_string needs deduction guides from basic_string_view
6006  template<typename _CharT, typename _Traits,
6007  typename _Allocator = allocator<_CharT>,
6008  typename = _RequireAllocator<_Allocator>>
6009  basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
6010  -> basic_string<_CharT, _Traits, _Allocator>;
6011 
6012  template<typename _CharT, typename _Traits,
6013  typename _Allocator = allocator<_CharT>,
6014  typename = _RequireAllocator<_Allocator>>
6015  basic_string(basic_string_view<_CharT, _Traits>,
6016  typename basic_string<_CharT, _Traits, _Allocator>::size_type,
6017  typename basic_string<_CharT, _Traits, _Allocator>::size_type,
6018  const _Allocator& = _Allocator())
6019  -> basic_string<_CharT, _Traits, _Allocator>;
6020 _GLIBCXX_END_NAMESPACE_CXX11
6021 #endif
6022 
6023  // operator+
6024  /**
6025  * @brief Concatenate two strings.
6026  * @param __lhs First string.
6027  * @param __rhs Last string.
6028  * @return New string with value of @a __lhs followed by @a __rhs.
6029  */
6030  template<typename _CharT, typename _Traits, typename _Alloc>
6031  basic_string<_CharT, _Traits, _Alloc>
6034  {
6036  __str.append(__rhs);
6037  return __str;
6038  }
6039 
6040  /**
6041  * @brief Concatenate C string and string.
6042  * @param __lhs First string.
6043  * @param __rhs Last string.
6044  * @return New string with value of @a __lhs followed by @a __rhs.
6045  */
6046  template<typename _CharT, typename _Traits, typename _Alloc>
6047  basic_string<_CharT,_Traits,_Alloc>
6048  operator+(const _CharT* __lhs,
6049  const basic_string<_CharT,_Traits,_Alloc>& __rhs);
6050 
6051  /**
6052  * @brief Concatenate character and string.
6053  * @param __lhs First string.
6054  * @param __rhs Last string.
6055  * @return New string with @a __lhs followed by @a __rhs.
6056  */
6057  template<typename _CharT, typename _Traits, typename _Alloc>
6058  basic_string<_CharT,_Traits,_Alloc>
6059  operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs);
6060 
6061  /**
6062  * @brief Concatenate string and C string.
6063  * @param __lhs First string.
6064  * @param __rhs Last string.
6065  * @return New string with @a __lhs followed by @a __rhs.
6066  */
6067  template<typename _CharT, typename _Traits, typename _Alloc>
6068  inline basic_string<_CharT, _Traits, _Alloc>
6070  const _CharT* __rhs)
6071  {
6073  __str.append(__rhs);
6074  return __str;
6075  }
6076 
6077  /**
6078  * @brief Concatenate string and character.
6079  * @param __lhs First string.
6080  * @param __rhs Last string.
6081  * @return New string with @a __lhs followed by @a __rhs.
6082  */
6083  template<typename _CharT, typename _Traits, typename _Alloc>
6084  inline basic_string<_CharT, _Traits, _Alloc>
6086  {
6087  typedef basic_string<_CharT, _Traits, _Alloc> __string_type;
6088  typedef typename __string_type::size_type __size_type;
6089  __string_type __str(__lhs);
6090  __str.append(__size_type(1), __rhs);
6091  return __str;
6092  }
6093 
6094 #if __cplusplus >= 201103L
6095  template<typename _CharT, typename _Traits, typename _Alloc>
6096  inline basic_string<_CharT, _Traits, _Alloc>
6097  operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6098  const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6099  { return std::move(__lhs.append(__rhs)); }
6100 
6101  template<typename _CharT, typename _Traits, typename _Alloc>
6102  inline basic_string<_CharT, _Traits, _Alloc>
6103  operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6104  basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6105  { return std::move(__rhs.insert(0, __lhs)); }
6106 
6107  template<typename _CharT, typename _Traits, typename _Alloc>
6108  inline basic_string<_CharT, _Traits, _Alloc>
6109  operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6110  basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6111  {
6112 #if _GLIBCXX_USE_CXX11_ABI
6113  using _Alloc_traits = allocator_traits<_Alloc>;
6114  bool __use_rhs = false;
6115  if _GLIBCXX17_CONSTEXPR (typename _Alloc_traits::is_always_equal{})
6116  __use_rhs = true;
6117  else if (__lhs.get_allocator() == __rhs.get_allocator())
6118  __use_rhs = true;
6119  if (__use_rhs)
6120 #endif
6121  {
6122  const auto __size = __lhs.size() + __rhs.size();
6123  if (__size > __lhs.capacity() && __size <= __rhs.capacity())
6124  return std::move(__rhs.insert(0, __lhs));
6125  }
6126  return std::move(__lhs.append(__rhs));
6127  }
6128 
6129  template<typename _CharT, typename _Traits, typename _Alloc>
6130  inline basic_string<_CharT, _Traits, _Alloc>
6131  operator+(const _CharT* __lhs,
6132  basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6133  { return std::move(__rhs.insert(0, __lhs)); }
6134 
6135  template<typename _CharT, typename _Traits, typename _Alloc>
6136  inline basic_string<_CharT, _Traits, _Alloc>
6137  operator+(_CharT __lhs,
6138  basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6139  { return std::move(__rhs.insert(0, 1, __lhs)); }
6140 
6141  template<typename _CharT, typename _Traits, typename _Alloc>
6142  inline basic_string<_CharT, _Traits, _Alloc>
6143  operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6144  const _CharT* __rhs)
6145  { return std::move(__lhs.append(__rhs)); }
6146 
6147  template<typename _CharT, typename _Traits, typename _Alloc>
6148  inline basic_string<_CharT, _Traits, _Alloc>
6149  operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6150  _CharT __rhs)
6151  { return std::move(__lhs.append(1, __rhs)); }
6152 #endif
6153 
6154  // operator ==
6155  /**
6156  * @brief Test equivalence of two strings.
6157  * @param __lhs First string.
6158  * @param __rhs Second string.
6159  * @return True if @a __lhs.compare(@a __rhs) == 0. False otherwise.
6160  */
6161  template<typename _CharT, typename _Traits, typename _Alloc>
6162  inline bool
6163  operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6165  _GLIBCXX_NOEXCEPT
6166  { return __lhs.compare(__rhs) == 0; }
6167 
6168  template<typename _CharT>
6169  inline
6170  typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value, bool>::__type
6171  operator==(const basic_string<_CharT>& __lhs,
6172  const basic_string<_CharT>& __rhs) _GLIBCXX_NOEXCEPT
6173  { return (__lhs.size() == __rhs.size()
6174  && !std::char_traits<_CharT>::compare(__lhs.data(), __rhs.data(),
6175  __lhs.size())); }
6176 
6177  /**
6178  * @brief Test equivalence of string and C string.
6179  * @param __lhs String.
6180  * @param __rhs C string.
6181  * @return True if @a __lhs.compare(@a __rhs) == 0. False otherwise.
6182  */
6183  template<typename _CharT, typename _Traits, typename _Alloc>
6184  inline bool
6185  operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6186  const _CharT* __rhs)
6187  { return __lhs.compare(__rhs) == 0; }
6188 
6189 #if __cpp_lib_three_way_comparison
6190  /**
6191  * @brief Three-way comparison of a string and a C string.
6192  * @param __lhs A string.
6193  * @param __rhs A null-terminated string.
6194  * @return A value indicating whether `__lhs` is less than, equal to,
6195  * greater than, or incomparable with `__rhs`.
6196  */
6197  template<typename _CharT, typename _Traits, typename _Alloc>
6198  inline auto
6199  operator<=>(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6200  const basic_string<_CharT, _Traits, _Alloc>& __rhs) noexcept
6201  -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
6202  { return __detail::__char_traits_cmp_cat<_Traits>(__lhs.compare(__rhs)); }
6203 
6204  /**
6205  * @brief Three-way comparison of a string and a C string.
6206  * @param __lhs A string.
6207  * @param __rhs A null-terminated string.
6208  * @return A value indicating whether `__lhs` is less than, equal to,
6209  * greater than, or incomparable with `__rhs`.
6210  */
6211  template<typename _CharT, typename _Traits, typename _Alloc>
6212  inline auto
6213  operator<=>(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6214  const _CharT* __rhs) noexcept
6215  -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
6216  { return __detail::__char_traits_cmp_cat<_Traits>(__lhs.compare(__rhs)); }
6217 #else
6218  /**
6219  * @brief Test equivalence of C string and string.
6220  * @param __lhs C string.
6221  * @param __rhs String.
6222  * @return True if @a __rhs.compare(@a __lhs) == 0. False otherwise.
6223  */
6224  template<typename _CharT, typename _Traits, typename _Alloc>
6225  inline bool
6226  operator==(const _CharT* __lhs,
6228  { return __rhs.compare(__lhs) == 0; }
6229 
6230  // operator !=
6231  /**
6232  * @brief Test difference of two strings.
6233  * @param __lhs First string.
6234  * @param __rhs Second string.
6235  * @return True if @a __lhs.compare(@a __rhs) != 0. False otherwise.
6236  */
6237  template<typename _CharT, typename _Traits, typename _Alloc>
6238  inline bool
6239  operator!=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6241  _GLIBCXX_NOEXCEPT
6242  { return !(__lhs == __rhs); }
6243 
6244  /**
6245  * @brief Test difference of C string and string.
6246  * @param __lhs C string.
6247  * @param __rhs String.
6248  * @return True if @a __rhs.compare(@a __lhs) != 0. False otherwise.
6249  */
6250  template<typename _CharT, typename _Traits, typename _Alloc>
6251  inline bool
6252  operator!=(const _CharT* __lhs,
6254  { return !(__lhs == __rhs); }
6255 
6256  /**
6257  * @brief Test difference of string and C string.
6258  * @param __lhs String.
6259  * @param __rhs C string.
6260  * @return True if @a __lhs.compare(@a __rhs) != 0. False otherwise.
6261  */
6262  template<typename _CharT, typename _Traits, typename _Alloc>
6263  inline bool
6264  operator!=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6265  const _CharT* __rhs)
6266  { return !(__lhs == __rhs); }
6267 
6268  // operator <
6269  /**
6270  * @brief Test if string precedes string.
6271  * @param __lhs First string.
6272  * @param __rhs Second string.
6273  * @return True if @a __lhs precedes @a __rhs. False otherwise.
6274  */
6275  template<typename _CharT, typename _Traits, typename _Alloc>
6276  inline bool
6277  operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6279  _GLIBCXX_NOEXCEPT
6280  { return __lhs.compare(__rhs) < 0; }
6281 
6282  /**
6283  * @brief Test if string precedes C string.
6284  * @param __lhs String.
6285  * @param __rhs C string.
6286  * @return True if @a __lhs precedes @a __rhs. False otherwise.
6287  */
6288  template<typename _CharT, typename _Traits, typename _Alloc>
6289  inline bool
6290  operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6291  const _CharT* __rhs)
6292  { return __lhs.compare(__rhs) < 0; }
6293 
6294  /**
6295  * @brief Test if C string precedes string.
6296  * @param __lhs C string.
6297  * @param __rhs String.
6298  * @return True if @a __lhs precedes @a __rhs. False otherwise.
6299  */
6300  template<typename _CharT, typename _Traits, typename _Alloc>
6301  inline bool
6302  operator<(const _CharT* __lhs,
6304  { return __rhs.compare(__lhs) > 0; }
6305 
6306  // operator >
6307  /**
6308  * @brief Test if string follows string.
6309  * @param __lhs First string.
6310  * @param __rhs Second string.
6311  * @return True if @a __lhs follows @a __rhs. False otherwise.
6312  */
6313  template<typename _CharT, typename _Traits, typename _Alloc>
6314  inline bool
6317  _GLIBCXX_NOEXCEPT
6318  { return __lhs.compare(__rhs) > 0; }
6319 
6320  /**
6321  * @brief Test if string follows C string.
6322  * @param __lhs String.
6323  * @param __rhs C string.
6324  * @return True if @a __lhs follows @a __rhs. False otherwise.
6325  */
6326  template<typename _CharT, typename _Traits, typename _Alloc>
6327  inline bool
6329  const _CharT* __rhs)
6330  { return __lhs.compare(__rhs) > 0; }
6331 
6332  /**
6333  * @brief Test if C string follows string.
6334  * @param __lhs C string.
6335  * @param __rhs String.
6336  * @return True if @a __lhs follows @a __rhs. False otherwise.
6337  */
6338  template<typename _CharT, typename _Traits, typename _Alloc>
6339  inline bool
6340  operator>(const _CharT* __lhs,
6342  { return __rhs.compare(__lhs) < 0; }
6343 
6344  // operator <=
6345  /**
6346  * @brief Test if string doesn't follow string.
6347  * @param __lhs First string.
6348  * @param __rhs Second string.
6349  * @return True if @a __lhs doesn't follow @a __rhs. False otherwise.
6350  */
6351  template<typename _CharT, typename _Traits, typename _Alloc>
6352  inline bool
6353  operator<=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6355  _GLIBCXX_NOEXCEPT
6356  { return __lhs.compare(__rhs) <= 0; }
6357 
6358  /**
6359  * @brief Test if string doesn't follow C string.
6360  * @param __lhs String.
6361  * @param __rhs C string.
6362  * @return True if @a __lhs doesn't follow @a __rhs. False otherwise.
6363  */
6364  template<typename _CharT, typename _Traits, typename _Alloc>
6365  inline bool
6366  operator<=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6367  const _CharT* __rhs)
6368  { return __lhs.compare(__rhs) <= 0; }
6369 
6370  /**
6371  * @brief Test if C string doesn't follow string.
6372  * @param __lhs C string.
6373  * @param __rhs String.
6374  * @return True if @a __lhs doesn't follow @a __rhs. False otherwise.
6375  */
6376  template<typename _CharT, typename _Traits, typename _Alloc>
6377  inline bool
6378  operator<=(const _CharT* __lhs,
6380  { return __rhs.compare(__lhs) >= 0; }
6381 
6382  // operator >=
6383  /**
6384  * @brief Test if string doesn't precede string.
6385  * @param __lhs First string.
6386  * @param __rhs Second string.
6387  * @return True if @a __lhs doesn't precede @a __rhs. False otherwise.
6388  */
6389  template<typename _CharT, typename _Traits, typename _Alloc>
6390  inline bool
6391  operator>=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6393  _GLIBCXX_NOEXCEPT
6394  { return __lhs.compare(__rhs) >= 0; }
6395 
6396  /**
6397  * @brief Test if string doesn't precede C string.
6398  * @param __lhs String.
6399  * @param __rhs C string.
6400  * @return True if @a __lhs doesn't precede @a __rhs. False otherwise.
6401  */
6402  template<typename _CharT, typename _Traits, typename _Alloc>
6403  inline bool
6404  operator>=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6405  const _CharT* __rhs)
6406  { return __lhs.compare(__rhs) >= 0; }
6407 
6408  /**
6409  * @brief Test if C string doesn't precede string.
6410  * @param __lhs C string.
6411  * @param __rhs String.
6412  * @return True if @a __lhs doesn't precede @a __rhs. False otherwise.
6413  */
6414  template<typename _CharT, typename _Traits, typename _Alloc>
6415  inline bool
6416  operator>=(const _CharT* __lhs,
6418  { return __rhs.compare(__lhs) <= 0; }
6419 #endif // three-way comparison
6420 
6421  /**
6422  * @brief Swap contents of two strings.
6423  * @param __lhs First string.
6424  * @param __rhs Second string.
6425  *
6426  * Exchanges the contents of @a __lhs and @a __rhs in constant time.
6427  */
6428  template<typename _CharT, typename _Traits, typename _Alloc>
6429  inline void
6432  _GLIBCXX_NOEXCEPT_IF(noexcept(__lhs.swap(__rhs)))
6433  { __lhs.swap(__rhs); }
6434 
6435 
6436  /**
6437  * @brief Read stream into a string.
6438  * @param __is Input stream.
6439  * @param __str Buffer to store into.
6440  * @return Reference to the input stream.
6441  *
6442  * Stores characters from @a __is into @a __str until whitespace is
6443  * found, the end of the stream is encountered, or str.max_size()
6444  * is reached. If is.width() is non-zero, that is the limit on the
6445  * number of characters stored into @a __str. Any previous
6446  * contents of @a __str are erased.
6447  */
6448  template<typename _CharT, typename _Traits, typename _Alloc>
6449  basic_istream<_CharT, _Traits>&
6450  operator>>(basic_istream<_CharT, _Traits>& __is,
6451  basic_string<_CharT, _Traits, _Alloc>& __str);
6452 
6453  template<>
6454  basic_istream<char>&
6455  operator>>(basic_istream<char>& __is, basic_string<char>& __str);
6456 
6457  /**
6458  * @brief Write string to a stream.
6459  * @param __os Output stream.
6460  * @param __str String to write out.
6461  * @return Reference to the output stream.
6462  *
6463  * Output characters of @a __str into os following the same rules as for
6464  * writing a C string.
6465  */
6466  template<typename _CharT, typename _Traits, typename _Alloc>
6467  inline basic_ostream<_CharT, _Traits>&
6468  operator<<(basic_ostream<_CharT, _Traits>& __os,
6470  {
6471  // _GLIBCXX_RESOLVE_LIB_DEFECTS
6472  // 586. string inserter not a formatted function
6473  return __ostream_insert(__os, __str.data(), __str.size());
6474  }
6475 
6476  /**
6477  * @brief Read a line from stream into a string.
6478  * @param __is Input stream.
6479  * @param __str Buffer to store into.
6480  * @param __delim Character marking end of line.
6481  * @return Reference to the input stream.
6482  *
6483  * Stores characters from @a __is into @a __str until @a __delim is
6484  * found, the end of the stream is encountered, or str.max_size()
6485  * is reached. Any previous contents of @a __str are erased. If
6486  * @a __delim is encountered, it is extracted but not stored into
6487  * @a __str.
6488  */
6489  template<typename _CharT, typename _Traits, typename _Alloc>
6490  basic_istream<_CharT, _Traits>&
6491  getline(basic_istream<_CharT, _Traits>& __is,
6492  basic_string<_CharT, _Traits, _Alloc>& __str, _CharT __delim);
6493 
6494  /**
6495  * @brief Read a line from stream into a string.
6496  * @param __is Input stream.
6497  * @param __str Buffer to store into.
6498  * @return Reference to the input stream.
6499  *
6500  * Stores characters from is into @a __str until &apos;\n&apos; is
6501  * found, the end of the stream is encountered, or str.max_size()
6502  * is reached. Any previous contents of @a __str are erased. If
6503  * end of line is encountered, it is extracted but not stored into
6504  * @a __str.
6505  */
6506  template<typename _CharT, typename _Traits, typename _Alloc>
6507  inline basic_istream<_CharT, _Traits>&
6510  { return std::getline(__is, __str, __is.widen('\n')); }
6511 
6512 #if __cplusplus >= 201103L
6513  /// Read a line from an rvalue stream into a string.
6514  template<typename _CharT, typename _Traits, typename _Alloc>
6515  inline basic_istream<_CharT, _Traits>&
6517  basic_string<_CharT, _Traits, _Alloc>& __str, _CharT __delim)
6518  { return std::getline(__is, __str, __delim); }
6519 
6520  /// Read a line from an rvalue stream into a string.
6521  template<typename _CharT, typename _Traits, typename _Alloc>
6522  inline basic_istream<_CharT, _Traits>&
6525  { return std::getline(__is, __str); }
6526 #endif
6527 
6528  template<>
6529  basic_istream<char>&
6530  getline(basic_istream<char>& __in, basic_string<char>& __str,
6531  char __delim);
6532 
6533 #ifdef _GLIBCXX_USE_WCHAR_T
6534  template<>
6535  basic_istream<wchar_t>&
6536  getline(basic_istream<wchar_t>& __in, basic_string<wchar_t>& __str,
6537  wchar_t __delim);
6538 #endif
6539 
6540 _GLIBCXX_END_NAMESPACE_VERSION
6541 } // namespace
6542 
6543 #if __cplusplus >= 201103L
6544 
6545 #include <ext/string_conversions.h>
6546 #include <bits/charconv.h>
6547 
6548 namespace std _GLIBCXX_VISIBILITY(default)
6549 {
6550 _GLIBCXX_BEGIN_NAMESPACE_VERSION
6551 _GLIBCXX_BEGIN_NAMESPACE_CXX11
6552 
6553 #if _GLIBCXX_USE_C99_STDLIB
6554  // 21.4 Numeric Conversions [string.conversions].
6555  inline int
6556  stoi(const string& __str, size_t* __idx = 0, int __base = 10)
6557  { return __gnu_cxx::__stoa<long, int>(&std::strtol, "stoi", __str.c_str(),
6558  __idx, __base); }
6559 
6560  inline long
6561  stol(const string& __str, size_t* __idx = 0, int __base = 10)
6562  { return __gnu_cxx::__stoa(&std::strtol, "stol", __str.c_str(),
6563  __idx, __base); }
6564 
6565  inline unsigned long
6566  stoul(const string& __str, size_t* __idx = 0, int __base = 10)
6567  { return __gnu_cxx::__stoa(&std::strtoul, "stoul", __str.c_str(),
6568  __idx, __base); }
6569 
6570  inline long long
6571  stoll(const string& __str, size_t* __idx = 0, int __base = 10)
6572  { return __gnu_cxx::__stoa(&std::strtoll, "stoll", __str.c_str(),
6573  __idx, __base); }
6574 
6575  inline unsigned long long
6576  stoull(const string& __str, size_t* __idx = 0, int __base = 10)
6577  { return __gnu_cxx::__stoa(&std::strtoull, "stoull", __str.c_str(),
6578  __idx, __base); }
6579 
6580  // NB: strtof vs strtod.
6581  inline float
6582  stof(const string& __str, size_t* __idx = 0)
6583  { return __gnu_cxx::__stoa(&std::strtof, "stof", __str.c_str(), __idx); }
6584 
6585  inline double
6586  stod(const string& __str, size_t* __idx = 0)
6587  { return __gnu_cxx::__stoa(&std::strtod, "stod", __str.c_str(), __idx); }
6588 
6589  inline long double
6590  stold(const string& __str, size_t* __idx = 0)
6591  { return __gnu_cxx::__stoa(&std::strtold, "stold", __str.c_str(), __idx); }
6592 #endif // _GLIBCXX_USE_C99_STDLIB
6593 
6594  // DR 1261. Insufficent overloads for to_string / to_wstring
6595 
6596  inline string
6597  to_string(int __val)
6598  {
6599  const bool __neg = __val < 0;
6600  const unsigned __uval = __neg ? (unsigned)~__val + 1u : __val;
6601  const auto __len = __detail::__to_chars_len(__uval);
6602  string __str(__neg + __len, '-');
6603  __detail::__to_chars_10_impl(&__str[__neg], __len, __uval);
6604  return __str;
6605  }
6606 
6607  inline string
6608  to_string(unsigned __val)
6609  {
6610  string __str(__detail::__to_chars_len(__val), '\0');
6611  __detail::__to_chars_10_impl(&__str[0], __str.size(), __val);
6612  return __str;
6613  }
6614 
6615  inline string
6616  to_string(long __val)
6617  {
6618  const bool __neg = __val < 0;
6619  const unsigned long __uval = __neg ? (unsigned long)~__val + 1ul : __val;
6620  const auto __len = __detail::__to_chars_len(__uval);
6621  string __str(__neg + __len, '-');
6622  __detail::__to_chars_10_impl(&__str[__neg], __len, __uval);
6623  return __str;
6624  }
6625 
6626  inline string
6627  to_string(unsigned long __val)
6628  {
6629  string __str(__detail::__to_chars_len(__val), '\0');
6630  __detail::__to_chars_10_impl(&__str[0], __str.size(), __val);
6631  return __str;
6632  }
6633 
6634  inline string
6635  to_string(long long __val)
6636  {
6637  const bool __neg = __val < 0;
6638  const unsigned long long __uval
6639  = __neg ? (unsigned long long)~__val + 1ull : __val;
6640  const auto __len = __detail::__to_chars_len(__uval);
6641  string __str(__neg + __len, '-');
6642  __detail::__to_chars_10_impl(&__str[__neg], __len, __uval);
6643  return __str;
6644  }
6645 
6646  inline string
6647  to_string(unsigned long long __val)
6648  {
6649  string __str(__detail::__to_chars_len(__val), '\0');
6650  __detail::__to_chars_10_impl(&__str[0], __str.size(), __val);
6651  return __str;
6652  }
6653 
6654 #if _GLIBCXX_USE_C99_STDIO
6655  // NB: (v)snprintf vs sprintf.
6656 
6657  inline string
6658  to_string(float __val)
6659  {
6660  const int __n =
6661  __gnu_cxx::__numeric_traits<float>::__max_exponent10 + 20;
6662  return __gnu_cxx::__to_xstring<string>(&std::vsnprintf, __n,
6663  "%f", __val);
6664  }
6665 
6666  inline string
6667  to_string(double __val)
6668  {
6669  const int __n =
6670  __gnu_cxx::__numeric_traits<double>::__max_exponent10 + 20;
6671  return __gnu_cxx::__to_xstring<string>(&std::vsnprintf, __n,
6672  "%f", __val);
6673  }
6674 
6675  inline string
6676  to_string(long double __val)
6677  {
6678  const int __n =
6679  __gnu_cxx::__numeric_traits<long double>::__max_exponent10 + 20;
6680  return __gnu_cxx::__to_xstring<string>(&std::vsnprintf, __n,
6681  "%Lf", __val);
6682  }
6683 #endif // _GLIBCXX_USE_C99_STDIO
6684 
6685 #if defined(_GLIBCXX_USE_WCHAR_T) && _GLIBCXX_USE_C99_WCHAR
6686  inline int
6687  stoi(const wstring& __str, size_t* __idx = 0, int __base = 10)
6688  { return __gnu_cxx::__stoa<long, int>(&std::wcstol, "stoi", __str.c_str(),
6689  __idx, __base); }
6690 
6691  inline long
6692  stol(const wstring& __str, size_t* __idx = 0, int __base = 10)
6693  { return __gnu_cxx::__stoa(&std::wcstol, "stol", __str.c_str(),
6694  __idx, __base); }
6695 
6696  inline unsigned long
6697  stoul(const wstring& __str, size_t* __idx = 0, int __base = 10)
6698  { return __gnu_cxx::__stoa(&std::wcstoul, "stoul", __str.c_str(),
6699  __idx, __base); }
6700 
6701  inline long long
6702  stoll(const wstring& __str, size_t* __idx = 0, int __base = 10)
6703  { return __gnu_cxx::__stoa(&std::wcstoll, "stoll", __str.c_str(),
6704  __idx, __base); }
6705 
6706  inline unsigned long long
6707  stoull(const wstring& __str, size_t* __idx = 0, int __base = 10)
6708  { return __gnu_cxx::__stoa(&std::wcstoull, "stoull", __str.c_str(),
6709  __idx, __base); }
6710 
6711  // NB: wcstof vs wcstod.
6712  inline float
6713  stof(const wstring& __str, size_t* __idx = 0)
6714  { return __gnu_cxx::__stoa(&std::wcstof, "stof", __str.c_str(), __idx); }
6715 
6716  inline double
6717  stod(const wstring& __str, size_t* __idx = 0)
6718  { return __gnu_cxx::__stoa(&std::wcstod, "stod", __str.c_str(), __idx); }
6719 
6720  inline long double
6721  stold(const wstring& __str, size_t* __idx = 0)
6722  { return __gnu_cxx::__stoa(&std::wcstold, "stold", __str.c_str(), __idx); }
6723 
6724 #ifndef _GLIBCXX_HAVE_BROKEN_VSWPRINTF
6725  // DR 1261.
6726  inline wstring
6727  to_wstring(int __val)
6728  { return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf, 4 * sizeof(int),
6729  L"%d", __val); }
6730 
6731  inline wstring
6732  to_wstring(unsigned __val)
6733  { return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf,
6734  4 * sizeof(unsigned),
6735  L"%u", __val); }
6736 
6737  inline wstring
6738  to_wstring(long __val)
6739  { return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf, 4 * sizeof(long),
6740  L"%ld", __val); }
6741 
6742  inline wstring
6743  to_wstring(unsigned long __val)
6744  { return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf,
6745  4 * sizeof(unsigned long),
6746  L"%lu", __val); }
6747 
6748  inline wstring
6749  to_wstring(long long __val)
6750  { return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf,
6751  4 * sizeof(long long),
6752  L"%lld", __val); }
6753 
6754  inline wstring
6755  to_wstring(unsigned long long __val)
6756  { return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf,
6757  4 * sizeof(unsigned long long),
6758  L"%llu", __val); }
6759 
6760  inline wstring
6761  to_wstring(float __val)
6762  {
6763  const int __n =
6764  __gnu_cxx::__numeric_traits<float>::__max_exponent10 + 20;
6765  return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf, __n,
6766  L"%f", __val);
6767  }
6768 
6769  inline wstring
6770  to_wstring(double __val)
6771  {
6772  const int __n =
6773  __gnu_cxx::__numeric_traits<double>::__max_exponent10 + 20;
6774  return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf, __n,
6775  L"%f", __val);
6776  }
6777 
6778  inline wstring
6779  to_wstring(long double __val)
6780  {
6781  const int __n =
6782  __gnu_cxx::__numeric_traits<long double>::__max_exponent10 + 20;
6783  return __gnu_cxx::__to_xstring<wstring>(&std::vswprintf, __n,
6784  L"%Lf", __val);
6785  }
6786 #endif // _GLIBCXX_HAVE_BROKEN_VSWPRINTF
6787 #endif // _GLIBCXX_USE_WCHAR_T && _GLIBCXX_USE_C99_WCHAR
6788 
6789 _GLIBCXX_END_NAMESPACE_CXX11
6790 _GLIBCXX_END_NAMESPACE_VERSION
6791 } // namespace
6792 
6793 #endif /* C++11 */
6794 
6795 #if __cplusplus >= 201103L
6796 
6797 #include <bits/functional_hash.h>
6798 
6799 namespace std _GLIBCXX_VISIBILITY(default)
6800 {
6801 _GLIBCXX_BEGIN_NAMESPACE_VERSION
6802 
6803  // DR 1182.
6804 
6805 #ifndef _GLIBCXX_COMPATIBILITY_CXX0X
6806  /// std::hash specialization for string.
6807  template<>
6808  struct hash<string>
6809  : public __hash_base<size_t, string>
6810  {
6811  size_t
6812  operator()(const string& __s) const noexcept
6813  { return std::_Hash_impl::hash(__s.data(), __s.length()); }
6814  };
6815 
6816  template<>
6817  struct __is_fast_hash<hash<string>> : std::false_type
6818  { };
6819 
6820 #ifdef _GLIBCXX_USE_WCHAR_T
6821  /// std::hash specialization for wstring.
6822  template<>
6823  struct hash<wstring>
6824  : public __hash_base<size_t, wstring>
6825  {
6826  size_t
6827  operator()(const wstring& __s) const noexcept
6828  { return std::_Hash_impl::hash(__s.data(),
6829  __s.length() * sizeof(wchar_t)); }
6830  };
6831 
6832  template<>
6833  struct __is_fast_hash<hash<wstring>> : std::false_type
6834  { };
6835 #endif
6836 #endif /* _GLIBCXX_COMPATIBILITY_CXX0X */
6837 
6838 #ifdef _GLIBCXX_USE_CHAR8_T
6839  /// std::hash specialization for u8string.
6840  template<>
6841  struct hash<u8string>
6842  : public __hash_base<size_t, u8string>
6843  {
6844  size_t
6845  operator()(const u8string& __s) const noexcept
6846  { return std::_Hash_impl::hash(__s.data(),
6847  __s.length() * sizeof(char8_t)); }
6848  };
6849 
6850  template<>
6851  struct __is_fast_hash<hash<u8string>> : std::false_type
6852  { };
6853 #endif
6854 
6855  /// std::hash specialization for u16string.
6856  template<>
6857  struct hash<u16string>
6858  : public __hash_base<size_t, u16string>
6859  {
6860  size_t
6861  operator()(const u16string& __s) const noexcept
6862  { return std::_Hash_impl::hash(__s.data(),
6863  __s.length() * sizeof(char16_t)); }
6864  };
6865 
6866  template<>
6867  struct __is_fast_hash<hash<u16string>> : std::false_type
6868  { };
6869 
6870  /// std::hash specialization for u32string.
6871  template<>
6872  struct hash<u32string>
6873  : public __hash_base<size_t, u32string>
6874  {
6875  size_t
6876  operator()(const u32string& __s) const noexcept
6877  { return std::_Hash_impl::hash(__s.data(),
6878  __s.length() * sizeof(char32_t)); }
6879  };
6880 
6881  template<>
6882  struct __is_fast_hash<hash<u32string>> : std::false_type
6883  { };
6884 
6885 #if __cplusplus >= 201402L
6886 
6887 #define __cpp_lib_string_udls 201304
6888 
6889  inline namespace literals
6890  {
6891  inline namespace string_literals
6892  {
6893 #pragma GCC diagnostic push
6894 #pragma GCC diagnostic ignored "-Wliteral-suffix"
6895  _GLIBCXX_DEFAULT_ABI_TAG
6896  inline basic_string<char>
6897  operator""s(const char* __str, size_t __len)
6898  { return basic_string<char>{__str, __len}; }
6899 
6900 #ifdef _GLIBCXX_USE_WCHAR_T
6901  _GLIBCXX_DEFAULT_ABI_TAG
6902  inline basic_string<wchar_t>
6903  operator""s(const wchar_t* __str, size_t __len)
6904  { return basic_string<wchar_t>{__str, __len}; }
6905 #endif
6906 
6907 #ifdef _GLIBCXX_USE_CHAR8_T
6908  _GLIBCXX_DEFAULT_ABI_TAG
6909  inline basic_string<char8_t>
6910  operator""s(const char8_t* __str, size_t __len)
6911  { return basic_string<char8_t>{__str, __len}; }
6912 #endif
6913 
6914  _GLIBCXX_DEFAULT_ABI_TAG
6915  inline basic_string<char16_t>
6916  operator""s(const char16_t* __str, size_t __len)
6917  { return basic_string<char16_t>{__str, __len}; }
6918 
6919  _GLIBCXX_DEFAULT_ABI_TAG
6920  inline basic_string<char32_t>
6921  operator""s(const char32_t* __str, size_t __len)
6922  { return basic_string<char32_t>{__str, __len}; }
6923 
6924 #pragma GCC diagnostic pop
6925  } // inline namespace string_literals
6926  } // inline namespace literals
6927 
6928 #if __cplusplus >= 201703L
6929  namespace __detail::__variant
6930  {
6931  template<typename> struct _Never_valueless_alt; // see <variant>
6932 
6933  // Provide the strong exception-safety guarantee when emplacing a
6934  // basic_string into a variant, but only if moving the string cannot throw.
6935  template<typename _Tp, typename _Traits, typename _Alloc>
6936  struct _Never_valueless_alt<std::basic_string<_Tp, _Traits, _Alloc>>
6937  : __and_<
6938  is_nothrow_move_constructible<std::basic_string<_Tp, _Traits, _Alloc>>,
6939  is_nothrow_move_assignable<std::basic_string<_Tp, _Traits, _Alloc>>
6940  >::type
6941  { };
6942  } // namespace __detail::__variant
6943 #endif // C++17
6944 #endif // C++14
6945 
6946 _GLIBCXX_END_NAMESPACE_VERSION
6947 } // namespace std
6948 
6949 #endif // C++11
6950 
6951 #endif /* _BASIC_STRING_H */
basic_string & operator=(initializer_list< _CharT > __l)
Set value to string constructed from initializer list.
basic_string & operator+=(_CharT __c)
Append a character.
size_type find_last_of(const basic_string &__str, size_type __pos=npos) const noexcept
Find last position of a character of string.
basic_string & insert(size_type __pos, const _CharT *__s)
Insert a C string.
Basis for explicit traits specializations.
Definition: char_traits.h:310
size_type find_first_not_of(const basic_string &__str, size_type __pos=0) const noexcept
Find position of a character not in string.
size_type find_last_not_of(const _CharT *__s, size_type __pos=npos) const noexcept
Find last position of a character not in C string.
basic_string & insert(size_type __pos1, const basic_string &__str, size_type __pos2, size_type __n=npos)
Insert a substring.
basic_string(const _Alloc &__a)
Construct an empty string using allocator a.
~basic_string() noexcept
Destroy the string instance.
iterator erase(iterator __position)
Remove one character.
Common iterator class.
size_type find_last_not_of(const basic_string &__str, size_type __pos=npos) const noexcept
Find last position of a character not in string.
integral_constant
Definition: type_traits:57
basic_istream< _CharT, _Traits > & getline(basic_istream< _CharT, _Traits > &__is, basic_string< _CharT, _Traits, _Alloc > &__str, _CharT __delim)
Read a line from stream into a string.
const _CharT * data() const noexcept
Return const pointer to contents.
void insert(iterator __p, initializer_list< _CharT > __l)
Insert an initializer_list of characters.
size_type length() const noexcept
Returns the number of characters in the string, not including any null-termination.
basic_string & replace(iterator __i1, iterator __i2, _InputIterator __k1, _InputIterator __k2)
Replace range of characters with range.
reference at(size_type __n)
Provides access to the data contained in the string.
void push_back(_CharT __c)
Append a single character.
const_reference operator[](size_type __pos) const noexcept
Subscript access to the data contained in the string.
size_type size() const noexcept
Returns the number of characters in the string, not including any null-termination.
void reserve(size_type __res_arg=0)
Attempt to preallocate enough memory for specified number of characters.
size_type capacity() const noexcept
const_iterator begin() const noexcept
Uniform interface to C++98 and C++11 allocators.
Managing sequences of characters and character-like objects.
basic_string & assign(const basic_string &__str)
Set value to contents of another string.
Template class basic_istream.
Definition: iosfwd:83
basic_string & assign(size_type __n, _CharT __c)
Set value to multiple characters.
basic_string & operator=(const _CharT *__s)
Copy contents of s into this string.
size_type copy(_CharT *__s, size_type __n, size_type __pos=0) const
Copy substring into C string.
reverse_iterator rend()
const_reference at(size_type __n) const
Provides access to the data contained in the string.
std::basic_istream< _CharT, _Traits > & operator>>(std::basic_istream< _CharT, _Traits > &__is, bitset< _Nb > &__x)
Global I/O operators for bitsets.
Definition: bitset:1472
basic_string & append(initializer_list< _CharT > __l)
Append an initializer_list of characters.
const_iterator cbegin() const noexcept
const_reverse_iterator rend() const noexcept
is_same
Definition: type_traits:582
basic_string & replace(size_type __pos1, size_type __n1, const basic_string &__str, size_type __pos2, size_type __n2=npos)
Replace characters with value from another string.
basic_string & replace(size_type __pos, size_type __n1, size_type __n2, _CharT __c)
Replace characters with multiple characters.
basic_string & erase(size_type __pos=0, size_type __n=npos)
Remove characters.
size_type find_first_not_of(const _CharT *__s, size_type __pos=0) const noexcept
Find position of a character not in C string.
size_type find(const _CharT *__s, size_type __pos=0) const noexcept
Find position of a C string.
size_type rfind(const _CharT *__s, size_type __pos=npos) const noexcept
Find last position of a C string.
char_type widen(char __c) const
Widens characters.
Definition: basic_ios.h:449
basic_string & assign(initializer_list< _CharT > __l)
Set value to an initializer_list of characters.
const_reference back() const noexcept
basic_string & replace(size_type __pos, size_type __n, const basic_string &__str)
Replace characters with value from another string.
basic_string & replace(iterator __i1, iterator __i2, initializer_list< _CharT > __l)
Replace range of characters with initializer_list.
basic_string & assign(const basic_string &__str, size_type __pos, size_type __n=npos)
Set value to a substring of a string.
reference operator[](size_type __pos)
Subscript access to the data contained in the string.
Uniform interface to all pointer-like types.
Definition: ptr_traits.h:83
basic_string & operator=(const basic_string &__str)
Assign the value of str to this string.
basic_string & replace(iterator __i1, iterator __i2, const basic_string &__str)
Replace range of characters with string.
iterator insert(iterator __p, _CharT __c)
Insert one character.
basic_string & append(const basic_string &__str)
Append a string to this string.
basic_string & append(const _CharT *__s)
Append a C string.
void resize(size_type __n)
Resizes the string to the specified number of characters.
size_type find_last_of(_CharT __c, size_type __pos=npos) const noexcept
Find last position of a character.
basic_string & operator=(basic_string &&__str) noexcept(/*conditional */)
Move assign the value of str to this string.
basic_string & operator+=(const _CharT *__s)
Append a C string.
basic_string substr(size_type __pos=0, size_type __n=npos) const
Get a substring.
const_iterator cend() const noexcept
allocator_type get_allocator() const noexcept
Return copy of allocator used to construct this string.
void pop_back()
Remove the last character.
void shrink_to_fit() noexcept
A non-binding request to reduce capacity() to size().
Uniform interface to all allocator types.
basic_string & assign(const _CharT *__s)
Set value to contents of a C string.
const_reference front() const noexcept
basic_string & replace(iterator __i1, iterator __i2, const _CharT *__s, size_type __n)
Replace range of characters with C substring.
const_reverse_iterator crend() const noexcept
basic_string & replace(size_type __pos, size_type __n1, const _CharT *__s)
Replace characters with value of a C string.
size_type rfind(const basic_string &__str, size_type __pos=npos) const noexcept
Find last position of a string.
static const size_type npos
Value returned by various member functions when they fail.
constexpr _Iterator __base(_Iterator __it)
size_type find_last_of(const _CharT *__s, size_type __pos=npos) const noexcept
Find last position of a character of C string.
size_type find(const basic_string &__str, size_type __pos=0) const noexcept
Find position of a string.
const_reverse_iterator rbegin() const noexcept
basic_string & insert(size_type __pos1, const basic_string &__str)
Insert value of a string.
reference back()
Primary class template hash.
Definition: typeindex:110
void noexcept()
Swap contents with another string.
size_type find_first_of(const basic_string &__str, size_type __pos=0) const noexcept
Find position of a character of string.
void resize(size_type __n, _CharT __c)
Resizes the string to the specified number of characters.
basic_string< wchar_t > wstring
A string of wchar_t.
Definition: stringfwd.h:83
const_iterator end() const noexcept
void insert(iterator __p, size_type __n, _CharT __c)
Insert multiple characters.
Marking input iterators.
void clear() noexcept
basic_string & append(_InputIterator __first, _InputIterator __last)
Append a range of characters.
basic_string & operator=(_CharT __c)
Set value to string of length 1.
int compare(const basic_string &__str) const
Compare to a string.
size_type find_first_of(_CharT __c, size_type __pos=0) const noexcept
Find position of a character.
const _CharT * c_str() const noexcept
Return const pointer to null-terminated contents.
constexpr complex< _Tp > operator+(const complex< _Tp > &__x, const complex< _Tp > &__y)
Return new complex value x plus y.
Definition: complex:331
void insert(iterator __p, _InputIterator __beg, _InputIterator __end)
Insert a range of characters.
basic_string & operator+=(initializer_list< _CharT > __l)
Append an initializer_list of characters.
size_type find_first_of(const _CharT *__s, size_type __pos=0) const noexcept
Find position of a character of C string.
basic_string & replace(iterator __i1, iterator __i2, const _CharT *__s)
Replace range of characters with C string.
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:230
size_type find(const _CharT *__s, size_type __pos, size_type __n) const noexcept
Find position of a C substring.
const_reverse_iterator crbegin() const noexcept
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:101
reverse_iterator rbegin()
bool empty() const noexcept
Forward iterators support a superset of input iterator operations.
reference front()
typename enable_if< _Cond, _Tp >::type enable_if_t
Alias template for enable_if.
Definition: type_traits:2554
basic_string & replace(iterator __i1, iterator __i2, size_type __n, _CharT __c)
Replace range of characters with multiple characters.
size_type max_size() const noexcept
Returns the size() of the largest possible string.
basic_string & insert(size_type __pos, size_type __n, _CharT __c)
Insert multiple characters.
basic_string & assign(_InputIterator __first, _InputIterator __last)
Set value to a range of characters.
basic_string & operator+=(const basic_string &__str)
Append a string to this string.
initializer_list