libstdc++-v3/include/bits/basic_string.tcc

   1 // Components for manipulating sequences of characters -*- C++ -*-
   2
   3 // Copyright (C) 1997-2025 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.tcc
  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 // Written by Jason Merrill based upon the specification by Takanori Adachi
  35 // in ANSI X3J16/94-0013R2.  Rewritten by Nathan Myers to ISO-14882.
  36 // Non-reference-counted implementation written by Paolo Carlini and
  37 // updated by Jonathan Wakely for ISO-14882-2011.
  38
  39 #ifndef _BASIC_STRING_TCC
  40 #define _BASIC_STRING_TCC 1
  41
  42 #ifdef _GLIBCXX_SYSHDR
  43 #pragma GCC system_header
  44 #endif
  45
  46 #pragma GCC diagnostic push
  47 #pragma GCC diagnostic ignored "-Wc++11-extensions"
  48
  49 #include <bits/cxxabi_forced.h>
  50
  51 namespace std _GLIBCXX_VISIBILITY(default)
  52 {
  53 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  54
  55 #if _GLIBCXX_USE_CXX11_ABI
  56
  57   template<typename _CharT, typename _Traits, typename _Alloc>
  58     const typename basic_string<_CharT, _Traits, _Alloc>::size_type
  59     basic_string<_CharT, _Traits, _Alloc>::npos;
  60
  61   template<typename _CharT, typename _Traits, typename _Alloc>
  62     _GLIBCXX20_CONSTEXPR
  63     void
  64     basic_string<_CharT, _Traits, _Alloc>::
  65     swap(basic_string& __s) _GLIBCXX_NOEXCEPT
  66     {
  67       if (this == std::__addressof(__s))
  68         return;
  69
  70       _Alloc_traits::_S_on_swap(_M_get_allocator(), __s._M_get_allocator());
  71
  72       if (_M_is_local())
  73         if (__s._M_is_local())
  74           {
  75             if (length() && __s.length())
  76               {
  77                 _CharT __tmp_data[_S_local_capacity + 1];
  78                 traits_type::copy(__tmp_data, __s._M_local_buf,
  79                                   __s.length() + 1);
  80                 traits_type::copy(__s._M_local_buf, _M_local_buf,
  81                                   length() + 1);
  82                 traits_type::copy(_M_local_buf, __tmp_data,
  83                                   __s.length() + 1);
  84               }
  85             else if (__s.length())
  86               {
  87                 _M_init_local_buf();
  88                 traits_type::copy(_M_local_buf, __s._M_local_buf,
  89                                   __s.length() + 1);
  90                 _M_length(__s.length());
  91                 __s._M_set_length(0);
  92                 return;
  93               }
  94             else if (length())
  95               {
  96                 __s._M_init_local_buf();
  97                 traits_type::copy(__s._M_local_buf, _M_local_buf,
  98                                   length() + 1);
  99                 __s._M_length(length());
 100                 _M_set_length(0);
 101                 return;
 102               }
 103           }
 104         else
 105           {
 106             const size_type __tmp_capacity = __s._M_allocated_capacity;
 107             __s._M_init_local_buf();
 108             traits_type::copy(__s._M_local_buf, _M_local_buf,
 109                               length() + 1);
 110             _M_data(__s._M_data());
 111             __s._M_data(__s._M_local_buf);
 112             _M_capacity(__tmp_capacity);
 113           }
 114       else
 115         {
 116           const size_type __tmp_capacity = _M_allocated_capacity;
 117           if (__s._M_is_local())
 118             {
 119               _M_init_local_buf();
 120               traits_type::copy(_M_local_buf, __s._M_local_buf,
 121                                 __s.length() + 1);
 122               __s._M_data(_M_data());
 123               _M_data(_M_local_buf);
 124             }
 125           else
 126             {
 127               pointer __tmp_ptr = _M_data();
 128               _M_data(__s._M_data());
 129               __s._M_data(__tmp_ptr);
 130               _M_capacity(__s._M_allocated_capacity);
 131             }
 132           __s._M_capacity(__tmp_capacity);
 133         }
 134
 135       const size_type __tmp_length = length();
 136       _M_length(__s.length());
 137       __s._M_length(__tmp_length);
 138     }
 139
 140   template<typename _CharT, typename _Traits, typename _Alloc>
 141     _GLIBCXX20_CONSTEXPR
 142     typename basic_string<_CharT, _Traits, _Alloc>::pointer
 143     basic_string<_CharT, _Traits, _Alloc>::
 144     _M_create(size_type& __capacity, size_type __old_capacity)
 145     {
 146       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 147       // 83.  String::npos vs. string::max_size()
 148       if (__capacity > max_size())
 149         std::__throw_length_error(__N("basic_string::_M_create"));
 150
 151       // The below implements an exponential growth policy, necessary to
 152       // meet amortized linear time requirements of the library: see
 153       // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
 154       if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
 155         {
 156           __capacity = 2 * __old_capacity;
 157           // Never allocate a string bigger than max_size.
 158           if (__capacity > max_size())
 159             __capacity = max_size();
 160         }
 161
 162       // NB: Need an array of char_type[__capacity], plus a terminating
 163       // null char_type() element.
 164       return _S_allocate(_M_get_allocator(), __capacity + 1);
 165     }
 166
 167   // NB: This is the special case for Input Iterators, used in
 168   // istreambuf_iterators, etc.
 169   // Input Iterators have a cost structure very different from
 170   // pointers, calling for a different coding style.
 171   template<typename _CharT, typename _Traits, typename _Alloc>
 172     template<typename _InIterator>
 173       _GLIBCXX20_CONSTEXPR
 174       void
 175       basic_string<_CharT, _Traits, _Alloc>::
 176       _M_construct(_InIterator __beg, _InIterator __end,
 177                    std::input_iterator_tag)
 178       {
 179         size_type __len = 0;
 180         size_type __capacity = size_type(_S_local_capacity);
 181
 182         _M_init_local_buf();
 183
 184         while (__beg != __end && __len < __capacity)
 185           {
 186             _M_local_buf[__len++] = *__beg;
 187             ++__beg;
 188           }
 189
 190         struct _Guard
 191         {
 192           _GLIBCXX20_CONSTEXPR
 193           explicit _Guard(basic_string* __s) : _M_guarded(__s) { }
 194
 195           _GLIBCXX20_CONSTEXPR
 196           ~_Guard() { if (_M_guarded) _M_guarded->_M_dispose(); }
 197
 198           basic_string* _M_guarded;
 199         } __guard(this);
 200
 201         while (__beg != __end)
 202           {
 203             if (__len == __capacity)
 204               {
 205                 // Allocate more space.
 206                 __capacity = __len + 1;
 207                 pointer __another = _M_create(__capacity, __len);
 208                 this->_S_copy(__another, _M_data(), __len);
 209                 _M_dispose();
 210                 _M_data(__another);
 211                 _M_capacity(__capacity);
 212               }
 213             traits_type::assign(_M_data()[__len++],
 214                                 static_cast<_CharT>(*__beg));
 215             ++__beg;
 216           }
 217
 218         __guard._M_guarded = 0;
 219
 220         _M_set_length(__len);
 221       }
 222
 223   template<typename _CharT, typename _Traits, typename _Alloc>
 224     template<typename _InIterator>
 225       _GLIBCXX20_CONSTEXPR
 226       void
 227       basic_string<_CharT, _Traits, _Alloc>::
 228       _M_construct(_InIterator __beg, _InIterator __end,
 229                    std::forward_iterator_tag)
 230       {
 231         size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
 232
 233         if (__dnew > size_type(_S_local_capacity))
 234           {
 235             _M_data(_M_create(__dnew, size_type(0)));
 236             _M_capacity(__dnew);
 237           }
 238         else
 239           _M_init_local_buf();
 240
 241         // Check for out_of_range and length_error exceptions.
 242         struct _Guard
 243         {
 244           _GLIBCXX20_CONSTEXPR
 245           explicit _Guard(basic_string* __s) : _M_guarded(__s) { }
 246
 247           _GLIBCXX20_CONSTEXPR
 248           ~_Guard() { if (_M_guarded) _M_guarded->_M_dispose(); }
 249
 250           basic_string* _M_guarded;
 251         } __guard(this);
 252
 253         this->_S_copy_chars(_M_data(), __beg, __end);
 254
 255         __guard._M_guarded = 0;
 256
 257         _M_set_length(__dnew);
 258       }
 259
 260   template<typename _CharT, typename _Traits, typename _Alloc>
 261     _GLIBCXX20_CONSTEXPR
 262     void
 263     basic_string<_CharT, _Traits, _Alloc>::
 264     _M_construct(size_type __n, _CharT __c)
 265     {
 266       if (__n > size_type(_S_local_capacity))
 267         {
 268           _M_data(_M_create(__n, size_type(0)));
 269           _M_capacity(__n);
 270         }
 271       else
 272         _M_init_local_buf();
 273
 274       if (__n)
 275         this->_S_assign(_M_data(), __n, __c);
 276
 277       _M_set_length(__n);
 278     }
 279
 280   // Length of string constructed is easier to propagate inter-procedurally
 281   // than difference between iterators.
 282   template<typename _CharT, typename _Traits, typename _Alloc>
 283     template<bool _Terminated>
 284     _GLIBCXX20_CONSTEXPR
 285     void
 286     basic_string<_CharT, _Traits, _Alloc>::
 287     _M_construct(const _CharT* __str, size_type __n)
 288     {
 289       if (__n > size_type(_S_local_capacity))
 290         {
 291           _M_data(_M_create(__n, size_type(0)));
 292           _M_capacity(__n);
 293         }
 294       else
 295         _M_init_local_buf();
 296
 297       if (__n || _Terminated)
 298         this->_S_copy(_M_data(), __str, __n + _Terminated);
 299
 300       _M_length(__n);
 301       if (!_Terminated)
 302         traits_type::assign(_M_data()[__n], _CharT());
 303     }
 304
 305   template<typename _CharT, typename _Traits, typename _Alloc>
 306     _GLIBCXX20_CONSTEXPR
 307     void
 308     basic_string<_CharT, _Traits, _Alloc>::
 309     _M_assign(const basic_string& __str)
 310     {
 311       if (this != std::__addressof(__str))
 312         {
 313           const size_type __rsize = __str.length();
 314           const size_type __capacity = capacity();
 315
 316           if (__rsize > __capacity)
 317             {
 318               size_type __new_capacity = __rsize;
 319               pointer __tmp = _M_create(__new_capacity, __capacity);
 320               _M_dispose();
 321               _M_data(__tmp);
 322               _M_capacity(__new_capacity);
 323             }
 324
 325           if (__rsize)
 326             this->_S_copy(_M_data(), __str._M_data(), __rsize);
 327
 328           _M_set_length(__rsize);
 329         }
 330     }
 331
 332   template<typename _CharT, typename _Traits, typename _Alloc>
 333     _GLIBCXX20_CONSTEXPR
 334     void
 335     basic_string<_CharT, _Traits, _Alloc>::
 336     reserve(size_type __res)
 337     {
 338       const size_type __capacity = capacity();
 339       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 340       // 2968. Inconsistencies between basic_string reserve and
 341       // vector/unordered_map/unordered_set reserve functions
 342       // P0966 reserve should not shrink
 343       if (__res <= __capacity)
 344         return;
 345
 346       pointer __tmp = _M_create(__res, __capacity);
 347       this->_S_copy(__tmp, _M_data(), length() + 1);
 348       _M_dispose();
 349       _M_data(__tmp);
 350       _M_capacity(__res);
 351     }
 352
 353   template<typename _CharT, typename _Traits, typename _Alloc>
 354     _GLIBCXX20_CONSTEXPR
 355     void
 356     basic_string<_CharT, _Traits, _Alloc>::
 357     _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 358               size_type __len2)
 359     {
 360       const size_type __how_much = length() - __pos - __len1;
 361
 362       size_type __new_capacity = length() + __len2 - __len1;
 363       pointer __r = _M_create(__new_capacity, capacity());
 364
 365       if (__pos)
 366         this->_S_copy(__r, _M_data(), __pos);
 367       if (__s && __len2)
 368         this->_S_copy(__r + __pos, __s, __len2);
 369       if (__how_much)
 370         this->_S_copy(__r + __pos + __len2,
 371                       _M_data() + __pos + __len1, __how_much);
 372
 373       _M_dispose();
 374       _M_data(__r);
 375       _M_capacity(__new_capacity);
 376     }
 377
 378   template<typename _CharT, typename _Traits, typename _Alloc>
 379     _GLIBCXX20_CONSTEXPR
 380     void
 381     basic_string<_CharT, _Traits, _Alloc>::
 382     _M_erase(size_type __pos, size_type __n)
 383     {
 384       const size_type __how_much = length() - __pos - __n;
 385
 386       if (__how_much && __n)
 387         this->_S_move(_M_data() + __pos, _M_data() + __pos + __n, __how_much);
 388
 389       _M_set_length(length() - __n);
 390     }
 391
 392   template<typename _CharT, typename _Traits, typename _Alloc>
 393     _GLIBCXX20_CONSTEXPR
 394     void
 395     basic_string<_CharT, _Traits, _Alloc>::
 396     reserve()
 397     {
 398       if (_M_is_local())
 399         return;
 400
 401       const size_type __length = length();
 402       const size_type __capacity = _M_allocated_capacity;
 403
 404       if (__length <= size_type(_S_local_capacity))
 405         {
 406           _M_init_local_buf();
 407           this->_S_copy(_M_local_buf, _M_data(), __length + 1);
 408           _M_destroy(__capacity);
 409           _M_data(_M_local_data());
 410         }
 411 #if __cpp_exceptions
 412       else if (__length < __capacity)
 413         try
 414           {
 415             pointer __tmp = _S_allocate(_M_get_allocator(), __length + 1);
 416             this->_S_copy(__tmp, _M_data(), __length + 1);
 417             _M_dispose();
 418             _M_data(__tmp);
 419             _M_capacity(__length);
 420           }
 421         catch (const __cxxabiv1::__forced_unwind&)
 422           { throw; }
 423         catch (...)
 424           { /* swallow the exception */ }
 425 #endif
 426     }
 427
 428   template<typename _CharT, typename _Traits, typename _Alloc>
 429     _GLIBCXX20_CONSTEXPR
 430     void
 431     basic_string<_CharT, _Traits, _Alloc>::
 432     resize(size_type __n, _CharT __c)
 433     {
 434       const size_type __size = this->size();
 435       if (__size < __n)
 436         this->append(__n - __size, __c);
 437       else if (__n < __size)
 438         this->_M_set_length(__n);
 439     }
 440
 441   template<typename _CharT, typename _Traits, typename _Alloc>
 442     _GLIBCXX20_CONSTEXPR
 443     basic_string<_CharT, _Traits, _Alloc>&
 444     basic_string<_CharT, _Traits, _Alloc>::
 445     _M_append(const _CharT* __s, size_type __n)
 446     {
 447       const size_type __len = __n + this->size();
 448
 449       if (__len <= this->capacity())
 450         {
 451           if (__n)
 452             this->_S_copy(this->_M_data() + this->size(), __s, __n);
 453         }
 454       else
 455         this->_M_mutate(this->size(), size_type(0), __s, __n);
 456
 457       this->_M_set_length(__len);
 458       return *this;
 459     }
 460
 461   template<typename _CharT, typename _Traits, typename _Alloc>
 462     template<typename _InputIterator>
 463       _GLIBCXX20_CONSTEXPR
 464       basic_string<_CharT, _Traits, _Alloc>&
 465       basic_string<_CharT, _Traits, _Alloc>::
 466       _M_replace_dispatch(const_iterator __i1, const_iterator __i2,
 467                           _InputIterator __k1, _InputIterator __k2,
 468                           std::__false_type)
 469       {
 470         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 471         // 2788. unintentionally require a default constructible allocator
 472         const basic_string __s(__k1, __k2, this->get_allocator());
 473         const size_type __n1 = __i2 - __i1;
 474         return _M_replace(__i1 - begin(), __n1, __s._M_data(),
 475                           __s.size());
 476       }
 477
 478   template<typename _CharT, typename _Traits, typename _Alloc>
 479     _GLIBCXX20_CONSTEXPR
 480     basic_string<_CharT, _Traits, _Alloc>&
 481     basic_string<_CharT, _Traits, _Alloc>::
 482     _M_replace_aux(size_type __pos1, size_type __n1, size_type __n2,
 483                    _CharT __c)
 484     {
 485       _M_check_length(__n1, __n2, "basic_string::_M_replace_aux");
 486
 487       const size_type __old_size = this->size();
 488       const size_type __new_size = __old_size + __n2 - __n1;
 489
 490       if (__new_size <= this->capacity())
 491         {
 492           pointer __p = this->_M_data() + __pos1;
 493
 494           const size_type __how_much = __old_size - __pos1 - __n1;
 495           if (__how_much && __n1 != __n2)
 496             this->_S_move(__p + __n2, __p + __n1, __how_much);
 497         }
 498       else
 499         this->_M_mutate(__pos1, __n1, 0, __n2);
 500
 501       if (__n2)
 502         this->_S_assign(this->_M_data() + __pos1, __n2, __c);
 503
 504       this->_M_set_length(__new_size);
 505       return *this;
 506     }
 507
 508   template<typename _CharT, typename _Traits, typename _Alloc>
 509     __attribute__((__noinline__, __noclone__, __cold__)) void
 510     basic_string<_CharT, _Traits, _Alloc>::
 511     _M_replace_cold(pointer __p, size_type __len1, const _CharT* __s,
 512                     const size_type __len2, const size_type __how_much)
 513     {
 514       // Work in-place.
 515       if (__len2 && __len2 <= __len1)
 516         this->_S_move(__p, __s, __len2);
 517       if (__how_much && __len1 != __len2)
 518         this->_S_move(__p + __len2, __p + __len1, __how_much);
 519       if (__len2 > __len1)
 520         {
 521           if (__s + __len2 <= __p + __len1)
 522             this->_S_move(__p, __s, __len2);
 523           else if (__s >= __p + __len1)
 524             {
 525               // Hint to middle end that __p and __s overlap
 526               // (PR 98465).
 527               const size_type __poff = (__s - __p) + (__len2 - __len1);
 528               this->_S_copy(__p, __p + __poff, __len2);
 529             }
 530           else
 531             {
 532               const size_type __nleft = (__p + __len1) - __s;
 533               this->_S_move(__p, __s, __nleft);
 534               this->_S_copy(__p + __nleft, __p + __len2, __len2 - __nleft);
 535             }
 536         }
 537     }
 538
 539   template<typename _CharT, typename _Traits, typename _Alloc>
 540     _GLIBCXX20_CONSTEXPR
 541     basic_string<_CharT, _Traits, _Alloc>&
 542     basic_string<_CharT, _Traits, _Alloc>::
 543     _M_replace(size_type __pos, size_type __len1, const _CharT* __s,
 544                const size_type __len2)
 545     {
 546       _M_check_length(__len1, __len2, "basic_string::_M_replace");
 547
 548       const size_type __old_size = this->size();
 549       const size_type __new_size = __old_size + __len2 - __len1;
 550
 551       if (__new_size <= this->capacity())
 552         {
 553           pointer __p = this->_M_data() + __pos;
 554
 555           const size_type __how_much = __old_size - __pos - __len1;
 556 #if __cpp_lib_is_constant_evaluated
 557           if (std::is_constant_evaluated())
 558             {
 559               auto __newp = _S_allocate(_M_get_allocator(), __new_size);
 560               _S_copy(__newp, this->_M_data(), __pos);
 561               _S_copy(__newp + __pos, __s, __len2);
 562               _S_copy(__newp + __pos + __len2, __p + __len1, __how_much);
 563               _S_copy(this->_M_data(), __newp, __new_size);
 564               this->_M_get_allocator().deallocate(__newp, __new_size);
 565             }
 566           else
 567 #endif
 568           if (__builtin_expect(_M_disjunct(__s), true))
 569             {
 570               if (__how_much && __len1 != __len2)
 571                 this->_S_move(__p + __len2, __p + __len1, __how_much);
 572               if (__len2)
 573                 this->_S_copy(__p, __s, __len2);
 574             }
 575           else
 576             _M_replace_cold(__p, __len1, __s, __len2, __how_much);
 577         }
 578       else
 579         this->_M_mutate(__pos, __len1, __s, __len2);
 580
 581       this->_M_set_length(__new_size);
 582       return *this;
 583     }
 584
 585   template<typename _CharT, typename _Traits, typename _Alloc>
 586     _GLIBCXX20_CONSTEXPR
 587     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 588     basic_string<_CharT, _Traits, _Alloc>::
 589     copy(_CharT* __s, size_type __n, size_type __pos) const
 590     {
 591       _M_check(__pos, "basic_string::copy");
 592       __n = _M_limit(__pos, __n);
 593       __glibcxx_requires_string_len(__s, __n);
 594       if (__n)
 595         _S_copy(__s, _M_data() + __pos, __n);
 596       // 21.3.5.7 par 3: do not append null.  (good.)
 597       return __n;
 598     }
 599
 600 #ifdef __glibcxx_string_resize_and_overwrite // C++ >= 23
 601   template<typename _CharT, typename _Traits, typename _Alloc>
 602   template<typename _Operation>
 603     [[__gnu__::__always_inline__]]
 604     constexpr void
 605     basic_string<_CharT, _Traits, _Alloc>::
 606     __resize_and_overwrite(const size_type __n, _Operation __op)
 607     { resize_and_overwrite<_Operation&>(__n, __op); }
 608 #endif
 609
 610 #if __cplusplus >= 201103L
 611   template<typename _CharT, typename _Traits, typename _Alloc>
 612   template<typename _Operation>
 613     _GLIBCXX20_CONSTEXPR void
 614     basic_string<_CharT, _Traits, _Alloc>::
 615 #ifdef __glibcxx_string_resize_and_overwrite // C++ >= 23
 616     resize_and_overwrite(const size_type __n, _Operation __op)
 617 #else
 618     __resize_and_overwrite(const size_type __n, _Operation __op)
 619 #endif
 620     {
 621       reserve(__n);
 622       _CharT* const __p = _M_data();
 623 #if __cpp_lib_is_constant_evaluated
 624       if (std::__is_constant_evaluated() && __n > size())
 625         traits_type::assign(__p + size(), __n - size(), _CharT());
 626 #endif
 627       struct _Terminator {
 628         _GLIBCXX20_CONSTEXPR ~_Terminator() { _M_this->_M_set_length(_M_r); }
 629         basic_string* _M_this;
 630         size_type _M_r;
 631       };
 632       _Terminator __term{this, 0};
 633       auto __r = std::move(__op)(__p + 0, __n + 0);
 634 #ifdef __cpp_lib_concepts
 635       static_assert(ranges::__detail::__is_integer_like<decltype(__r)>);
 636 #else
 637       static_assert(__gnu_cxx::__is_integer_nonstrict<decltype(__r)>::__value,
 638                     "resize_and_overwrite operation must return an integer");
 639 #endif
 640       _GLIBCXX_DEBUG_ASSERT(__r >= 0 && size_type(__r) <= __n);
 641       __term._M_r = size_type(__r);
 642       if (__term._M_r > __n)
 643         __builtin_unreachable();
 644     }
 645 #endif // C++11
 646
 647 #endif  // _GLIBCXX_USE_CXX11_ABI
 648
 649 #if __glibcxx_constexpr_string >= 201907L
 650 # define _GLIBCXX_STRING_CONSTEXPR constexpr
 651 #else
 652 # define _GLIBCXX_STRING_CONSTEXPR
 653 #endif
 654   template<typename _CharT, typename _Traits, typename _Alloc>
 655     _GLIBCXX_STRING_CONSTEXPR
 656     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 657     basic_string<_CharT, _Traits, _Alloc>::
 658     find(const _CharT* __s, size_type __pos, size_type __n) const
 659     _GLIBCXX_NOEXCEPT
 660     {
 661       __glibcxx_requires_string_len(__s, __n);
 662       const size_type __size = this->size();
 663
 664       if (__n == 0)
 665         return __pos <= __size ? __pos : npos;
 666       if (__pos >= __size)
 667         return npos;
 668
 669       const _CharT __elem0 = __s[0];
 670       const _CharT* const __data = data();
 671       const _CharT* __first = __data + __pos;
 672       const _CharT* const __last = __data + __size;
 673       size_type __len = __size - __pos;
 674
 675       while (__len >= __n)
 676         {
 677           // Find the first occurrence of __elem0:
 678           __first = traits_type::find(__first, __len - __n + 1, __elem0);
 679           if (!__first)
 680             return npos;
 681           // Compare the full strings from the first occurrence of __elem0.
 682           // We already know that __first[0] == __s[0] but compare them again
 683           // anyway because __s is probably aligned, which helps memcmp.
 684           if (traits_type::compare(__first, __s, __n) == 0)
 685             return __first - __data;
 686           __len = __last - ++__first;
 687         }
 688       return npos;
 689     }
 690
 691   template<typename _CharT, typename _Traits, typename _Alloc>
 692     _GLIBCXX_STRING_CONSTEXPR
 693     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 694     basic_string<_CharT, _Traits, _Alloc>::
 695     find(_CharT __c, size_type __pos) const _GLIBCXX_NOEXCEPT
 696     {
 697       size_type __ret = npos;
 698       const size_type __size = this->size();
 699       if (__pos < __size)
 700         {
 701           const _CharT* __data = _M_data();
 702           const size_type __n = __size - __pos;
 703           const _CharT* __p = traits_type::find(__data + __pos, __n, __c);
 704           if (__p)
 705             __ret = __p - __data;
 706         }
 707       return __ret;
 708     }
 709
 710   template<typename _CharT, typename _Traits, typename _Alloc>
 711     _GLIBCXX_STRING_CONSTEXPR
 712     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 713     basic_string<_CharT, _Traits, _Alloc>::
 714     rfind(const _CharT* __s, size_type __pos, size_type __n) const
 715     _GLIBCXX_NOEXCEPT
 716     {
 717       __glibcxx_requires_string_len(__s, __n);
 718       const size_type __size = this->size();
 719       if (__n <= __size)
 720         {
 721           __pos = std::min(size_type(__size - __n), __pos);
 722           const _CharT* __data = _M_data();
 723           do
 724             {
 725               if (traits_type::compare(__data + __pos, __s, __n) == 0)
 726                 return __pos;
 727             }
 728           while (__pos-- > 0);
 729         }
 730       return npos;
 731     }
 732
 733   template<typename _CharT, typename _Traits, typename _Alloc>
 734     _GLIBCXX_STRING_CONSTEXPR
 735     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 736     basic_string<_CharT, _Traits, _Alloc>::
 737     rfind(_CharT __c, size_type __pos) const _GLIBCXX_NOEXCEPT
 738     {
 739       size_type __size = this->size();
 740       if (__size)
 741         {
 742           if (--__size > __pos)
 743             __size = __pos;
 744           for (++__size; __size-- > 0; )
 745             if (traits_type::eq(_M_data()[__size], __c))
 746               return __size;
 747         }
 748       return npos;
 749     }
 750
 751   template<typename _CharT, typename _Traits, typename _Alloc>
 752     _GLIBCXX_STRING_CONSTEXPR
 753     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 754     basic_string<_CharT, _Traits, _Alloc>::
 755     find_first_of(const _CharT* __s, size_type __pos, size_type __n) const
 756     _GLIBCXX_NOEXCEPT
 757     {
 758       __glibcxx_requires_string_len(__s, __n);
 759       for (; __n && __pos < this->size(); ++__pos)
 760         {
 761           const _CharT* __p = traits_type::find(__s, __n, _M_data()[__pos]);
 762           if (__p)
 763             return __pos;
 764         }
 765       return npos;
 766     }
 767
 768   template<typename _CharT, typename _Traits, typename _Alloc>
 769     _GLIBCXX_STRING_CONSTEXPR
 770     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 771     basic_string<_CharT, _Traits, _Alloc>::
 772     find_last_of(const _CharT* __s, size_type __pos, size_type __n) const
 773     _GLIBCXX_NOEXCEPT
 774     {
 775       __glibcxx_requires_string_len(__s, __n);
 776       size_type __size = this->size();
 777       if (__size && __n)
 778         {
 779           if (--__size > __pos)
 780             __size = __pos;
 781           do
 782             {
 783               if (traits_type::find(__s, __n, _M_data()[__size]))
 784                 return __size;
 785             }
 786           while (__size-- != 0);
 787         }
 788       return npos;
 789     }
 790
 791   template<typename _CharT, typename _Traits, typename _Alloc>
 792     _GLIBCXX_STRING_CONSTEXPR
 793     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 794     basic_string<_CharT, _Traits, _Alloc>::
 795     find_first_not_of(const _CharT* __s, size_type __pos, size_type __n) const
 796     _GLIBCXX_NOEXCEPT
 797     {
 798       __glibcxx_requires_string_len(__s, __n);
 799       for (; __pos < this->size(); ++__pos)
 800         if (!traits_type::find(__s, __n, _M_data()[__pos]))
 801           return __pos;
 802       return npos;
 803     }
 804
 805   template<typename _CharT, typename _Traits, typename _Alloc>
 806     _GLIBCXX_STRING_CONSTEXPR
 807     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 808     basic_string<_CharT, _Traits, _Alloc>::
 809     find_first_not_of(_CharT __c, size_type __pos) const _GLIBCXX_NOEXCEPT
 810     {
 811       for (; __pos < this->size(); ++__pos)
 812         if (!traits_type::eq(_M_data()[__pos], __c))
 813           return __pos;
 814       return npos;
 815     }
 816
 817   template<typename _CharT, typename _Traits, typename _Alloc>
 818     _GLIBCXX_STRING_CONSTEXPR
 819     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 820     basic_string<_CharT, _Traits, _Alloc>::
 821     find_last_not_of(const _CharT* __s, size_type __pos, size_type __n) const
 822     _GLIBCXX_NOEXCEPT
 823     {
 824       __glibcxx_requires_string_len(__s, __n);
 825       size_type __size = this->size();
 826       if (__size)
 827         {
 828           if (--__size > __pos)
 829             __size = __pos;
 830           do
 831             {
 832               if (!traits_type::find(__s, __n, _M_data()[__size]))
 833                 return __size;
 834             }
 835           while (__size--);
 836         }
 837       return npos;
 838     }
 839
 840   template<typename _CharT, typename _Traits, typename _Alloc>
 841     _GLIBCXX_STRING_CONSTEXPR
 842     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 843     basic_string<_CharT, _Traits, _Alloc>::
 844     find_last_not_of(_CharT __c, size_type __pos) const _GLIBCXX_NOEXCEPT
 845     {
 846       size_type __size = this->size();
 847       if (__size)
 848         {
 849           if (--__size > __pos)
 850             __size = __pos;
 851           do
 852             {
 853               if (!traits_type::eq(_M_data()[__size], __c))
 854                 return __size;
 855             }
 856           while (__size--);
 857         }
 858       return npos;
 859     }
 860
 861 #undef _GLIBCXX_STRING_CONSTEXPR
 862
 863   // 21.3.7.9 basic_string::getline and operators
 864   template<typename _CharT, typename _Traits, typename _Alloc>
 865     basic_istream<_CharT, _Traits>&
 866     operator>>(basic_istream<_CharT, _Traits>& __in,
 867                basic_string<_CharT, _Traits, _Alloc>& __str)
 868     {
 869       typedef basic_istream<_CharT, _Traits>            __istream_type;
 870       typedef basic_string<_CharT, _Traits, _Alloc>     __string_type;
 871       typedef typename __istream_type::ios_base         __ios_base;
 872       typedef typename __istream_type::int_type         __int_type;
 873       typedef typename __string_type::size_type         __size_type;
 874       typedef ctype<_CharT>                             __ctype_type;
 875       typedef typename __ctype_type::ctype_base         __ctype_base;
 876
 877       __size_type __extracted = 0;
 878       typename __ios_base::iostate __err = __ios_base::goodbit;
 879       typename __istream_type::sentry __cerb(__in, false);
 880       if (__cerb)
 881         {
 882           __try
 883             {
 884               // Avoid reallocation for common case.
 885               __str.erase();
 886               _CharT __buf[128];
 887               __size_type __len = 0;
 888               const streamsize __w = __in.width();
 889               const __size_type __n = __w > 0 ? static_cast<__size_type>(__w)
 890                                               : __str.max_size();
 891               const __ctype_type& __ct = use_facet<__ctype_type>(__in.getloc());
 892               const __int_type __eof = _Traits::eof();
 893               __int_type __c = __in.rdbuf()->sgetc();
 894
 895               while (__extracted < __n
 896                      && !_Traits::eq_int_type(__c, __eof)
 897                      && !__ct.is(__ctype_base::space,
 898                                  _Traits::to_char_type(__c)))
 899                 {
 900                   if (__len == sizeof(__buf) / sizeof(_CharT))
 901                     {
 902                       __str.append(__buf, sizeof(__buf) / sizeof(_CharT));
 903                       __len = 0;
 904                     }
 905                   __buf[__len++] = _Traits::to_char_type(__c);
 906                   ++__extracted;
 907                   __c = __in.rdbuf()->snextc();
 908                 }
 909               __str.append(__buf, __len);
 910
 911               if (__extracted < __n && _Traits::eq_int_type(__c, __eof))
 912                 __err |= __ios_base::eofbit;
 913               __in.width(0);
 914             }
 915           __catch(__cxxabiv1::__forced_unwind&)
 916             {
 917               __in._M_setstate(__ios_base::badbit);
 918               __throw_exception_again;
 919             }
 920           __catch(...)
 921             {
 922               // _GLIBCXX_RESOLVE_LIB_DEFECTS
 923               // 91. Description of operator>> and getline() for string<>
 924               // might cause endless loop
 925               __in._M_setstate(__ios_base::badbit);
 926             }
 927         }
 928       // 211.  operator>>(istream&, string&) doesn't set failbit
 929       if (!__extracted)
 930         __err |= __ios_base::failbit;
 931       if (__err)
 932         __in.setstate(__err);
 933       return __in;
 934     }
 935
 936   template<typename _CharT, typename _Traits, typename _Alloc>
 937     basic_istream<_CharT, _Traits>&
 938     getline(basic_istream<_CharT, _Traits>& __in,
 939             basic_string<_CharT, _Traits, _Alloc>& __str, _CharT __delim)
 940     {
 941       typedef basic_istream<_CharT, _Traits>            __istream_type;
 942       typedef basic_string<_CharT, _Traits, _Alloc>     __string_type;
 943       typedef typename __istream_type::ios_base         __ios_base;
 944       typedef typename __istream_type::int_type         __int_type;
 945       typedef typename __string_type::size_type         __size_type;
 946
 947       __size_type __extracted = 0;
 948       const __size_type __n = __str.max_size();
 949       typename __ios_base::iostate __err = __ios_base::goodbit;
 950       typename __istream_type::sentry __cerb(__in, true);
 951       if (__cerb)
 952         {
 953           __try
 954             {
 955               __str.erase();
 956               const __int_type __idelim = _Traits::to_int_type(__delim);
 957               const __int_type __eof = _Traits::eof();
 958               __int_type __c = __in.rdbuf()->sgetc();
 959
 960               while (__extracted < __n
 961                      && !_Traits::eq_int_type(__c, __eof)
 962                      && !_Traits::eq_int_type(__c, __idelim))
 963                 {
 964                   __str += _Traits::to_char_type(__c);
 965                   ++__extracted;
 966                   __c = __in.rdbuf()->snextc();
 967                 }
 968
 969               if (_Traits::eq_int_type(__c, __eof))
 970                 __err |= __ios_base::eofbit;
 971               else if (_Traits::eq_int_type(__c, __idelim))
 972                 {
 973                   ++__extracted;
 974                   __in.rdbuf()->sbumpc();
 975                 }
 976               else
 977                 __err |= __ios_base::failbit;
 978             }
 979           __catch(__cxxabiv1::__forced_unwind&)
 980             {
 981               __in._M_setstate(__ios_base::badbit);
 982               __throw_exception_again;
 983             }
 984           __catch(...)
 985             {
 986               // _GLIBCXX_RESOLVE_LIB_DEFECTS
 987               // 91. Description of operator>> and getline() for string<>
 988               // might cause endless loop
 989               __in._M_setstate(__ios_base::badbit);
 990             }
 991         }
 992       if (!__extracted)
 993         __err |= __ios_base::failbit;
 994       if (__err)
 995         __in.setstate(__err);
 996       return __in;
 997     }
 998
 999   // Inhibit implicit instantiations for required instantiations,
1000   // which are defined via explicit instantiations elsewhere.
1001 #if _GLIBCXX_EXTERN_TEMPLATE
1002   // The explicit instantiation definitions in src/c++11/string-inst.cc and
1003   // src/c++17/string-inst.cc only instantiate the members required for C++17
1004   // and earlier standards (so not C++20's starts_with and ends_with).
1005   // Suppress the explicit instantiation declarations for C++20, so C++20
1006   // code will implicitly instantiate std::string and std::wstring as needed.
1007 # if __cplusplus <= 201703L && _GLIBCXX_EXTERN_TEMPLATE > 0
1008   extern template class basic_string<char>;
1009 # elif ! _GLIBCXX_USE_CXX11_ABI
1010   // Still need to prevent implicit instantiation of the COW empty rep,
1011   // to ensure the definition in libstdc++.so is unique (PR 86138).
1012   extern template basic_string<char>::size_type
1013     basic_string<char>::_Rep::_S_empty_rep_storage[];
1014 # elif _GLIBCXX_EXTERN_TEMPLATE > 0
1015   // Export _M_replace_cold even for C++20.
1016   extern template void
1017     basic_string<char>::_M_replace_cold(char *, size_type, const char*,
1018                                         const size_type, const size_type);
1019 # endif
1020
1021   extern template
1022     basic_istream<char>&
1023     operator>>(basic_istream<char>&, string&);
1024   extern template
1025     basic_ostream<char>&
1026     operator<<(basic_ostream<char>&, const string&);
1027   extern template
1028     basic_istream<char>&
1029     getline(basic_istream<char>&, string&, char);
1030   extern template
1031     basic_istream<char>&
1032     getline(basic_istream<char>&, string&);
1033
1034 #ifdef _GLIBCXX_USE_WCHAR_T
1035 # if __cplusplus <= 201703L && _GLIBCXX_EXTERN_TEMPLATE > 0
1036   extern template class basic_string<wchar_t>;
1037 # elif ! _GLIBCXX_USE_CXX11_ABI
1038   extern template basic_string<wchar_t>::size_type
1039     basic_string<wchar_t>::_Rep::_S_empty_rep_storage[];
1040 # elif _GLIBCXX_EXTERN_TEMPLATE > 0
1041   // Export _M_replace_cold even for C++20.
1042   extern template void
1043     basic_string<wchar_t>::_M_replace_cold(wchar_t*, size_type, const wchar_t*,
1044                                            const size_type, const size_type);
1045 # endif
1046
1047   extern template
1048     basic_istream<wchar_t>&
1049     operator>>(basic_istream<wchar_t>&, wstring&);
1050   extern template
1051     basic_ostream<wchar_t>&
1052     operator<<(basic_ostream<wchar_t>&, const wstring&);
1053   extern template
1054     basic_istream<wchar_t>&
1055     getline(basic_istream<wchar_t>&, wstring&, wchar_t);
1056   extern template
1057     basic_istream<wchar_t>&
1058     getline(basic_istream<wchar_t>&, wstring&);
1059 #endif // _GLIBCXX_USE_WCHAR_T
1060 #endif // _GLIBCXX_EXTERN_TEMPLATE
1061
1062 _GLIBCXX_END_NAMESPACE_VERSION
1063 } // namespace std
1064
1065 #pragma GCC diagnostic pop
1066 #endif