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The C and C++ Include Header Files
/usr/include/c++/13/ext/rc_string_base.h
$ cat -n /usr/include/c++/13/ext/rc_string_base.h 1 // Reference-counted versatile string base -*- C++ -*- 2 3 // Copyright (C) 2005-2023 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 ext/rc_string_base.h 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{ext/vstring.h} 28 */ 29 30 #ifndef _RC_STRING_BASE_H 31 #define _RC_STRING_BASE_H 1 32 33 #include <bits/requires_hosted.h> // GNU extensions are currently omitted 34 35 #include <ext/atomicity.h> 36 #include <ext/alloc_traits.h> 37 #include <bits/stl_iterator_base_funcs.h> 38 39 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 40 { 41 _GLIBCXX_BEGIN_NAMESPACE_VERSION 42 43 /** 44 * Documentation? What's that? 45 * Nathan Myers <ncm@cantrip.org>. 46 * 47 * A string looks like this: 48 * 49 * @code 50 * [_Rep] 51 * _M_length 52 * [__rc_string_base<char_type>] _M_capacity 53 * _M_dataplus _M_refcount 54 * _M_p ----------------> unnamed array of char_type 55 * @endcode 56 * 57 * Where the _M_p points to the first character in the string, and 58 * you cast it to a pointer-to-_Rep and subtract 1 to get a 59 * pointer to the header. 60 * 61 * This approach has the enormous advantage that a string object 62 * requires only one allocation. All the ugliness is confined 63 * within a single pair of inline functions, which each compile to 64 * a single @a add instruction: _Rep::_M_refdata(), and 65 * __rc_string_base::_M_rep(); and the allocation function which gets a 66 * block of raw bytes and with room enough and constructs a _Rep 67 * object at the front. 68 * 69 * The reason you want _M_data pointing to the character array and 70 * not the _Rep is so that the debugger can see the string 71 * contents. (Probably we should add a non-inline member to get 72 * the _Rep for the debugger to use, so users can check the actual 73 * string length.) 74 * 75 * Note that the _Rep object is a POD so that you can have a 76 * static <em>empty string</em> _Rep object already @a constructed before 77 * static constructors have run. The reference-count encoding is 78 * chosen so that a 0 indicates one reference, so you never try to 79 * destroy the empty-string _Rep object. 80 * 81 * All but the last paragraph is considered pretty conventional 82 * for a C++ string implementation. 83 */ 84 template<typename _CharT, typename _Traits, typename _Alloc> 85 class __rc_string_base 86 : protected __vstring_utility<_CharT, _Traits, _Alloc> 87 { 88 public: 89 typedef _Traits traits_type; 90 typedef typename _Traits::char_type value_type; 91 typedef _Alloc allocator_type; 92 93 typedef __vstring_utility<_CharT, _Traits, _Alloc> _Util_Base; 94 typedef typename _Util_Base::_CharT_alloc_type _CharT_alloc_type; 95 typedef typename _CharT_alloc_type::size_type size_type; 96 97 private: 98 // _Rep: string representation 99 // Invariants: 100 // 1. String really contains _M_length + 1 characters: due to 21.3.4 101 // must be kept null-terminated. 102 // 2. _M_capacity >= _M_length 103 // Allocated memory is always (_M_capacity + 1) * sizeof(_CharT). 104 // 3. _M_refcount has three states: 105 // -1: leaked, one reference, no ref-copies allowed, non-const. 106 // 0: one reference, non-const. 107 // n>0: n + 1 references, operations require a lock, const. 108 // 4. All fields == 0 is an empty string, given the extra storage 109 // beyond-the-end for a null terminator; thus, the shared 110 // empty string representation needs no constructor. 111 struct _Rep 112 { 113 union 114 { 115 struct 116 { 117 size_type _M_length; 118 size_type _M_capacity; 119 _Atomic_word _M_refcount; 120 } _M_info; 121 122 // Only for alignment purposes. 123 _CharT _M_align; 124 }; 125 126 typedef typename __alloc_traits<_Alloc>::template rebind<_Rep>::other 127 _Rep_alloc_type; 128 129 _CharT* 130 _M_refdata() throw() 131 { return reinterpret_cast<_CharT*>(this + 1); } 132 133 _CharT* 134 _M_refcopy() throw() 135 { 136 __atomic_add_dispatch(&_M_info._M_refcount, 1); 137 return _M_refdata(); 138 } // XXX MT 139 140 void 141 _M_set_length(size_type __n) 142 { 143 _M_info._M_refcount = 0; // One reference. 144 _M_info._M_length = __n; 145 // grrr. (per 21.3.4) 146 // You cannot leave those LWG people alone for a second. 147 traits_type::assign(_M_refdata()[__n], _CharT()); 148 } 149 150 // Create & Destroy 151 static _Rep* 152 _S_create(size_type, size_type, const _Alloc&); 153 154 void 155 _M_destroy(const _Alloc&) throw(); 156 157 _CharT* 158 _M_clone(const _Alloc&, size_type __res = 0); 159 }; 160 161 struct _Rep_empty 162 : public _Rep 163 { 164 _CharT _M_terminal; 165 }; 166 167 static _Rep_empty _S_empty_rep; 168 169 // The maximum number of individual char_type elements of an 170 // individual string is determined by _S_max_size. This is the 171 // value that will be returned by max_size(). (Whereas npos 172 // is the maximum number of bytes the allocator can allocate.) 173 // If one was to divvy up the theoretical largest size string, 174 // with a terminating character and m _CharT elements, it'd 175 // look like this: 176 // npos = sizeof(_Rep) + (m * sizeof(_CharT)) + sizeof(_CharT) 177 // + sizeof(_Rep) - 1 178 // (NB: last two terms for rounding reasons, see _M_create below) 179 // Solving for m: 180 // m = ((npos - 2 * sizeof(_Rep) + 1) / sizeof(_CharT)) - 1 181 // In addition, this implementation halves this amount. 182 enum { _S_max_size = (((static_cast<size_type>(-1) - 2 * sizeof(_Rep) 183 + 1) / sizeof(_CharT)) - 1) / 2 }; 184 185 // Data Member (private): 186 mutable typename _Util_Base::template _Alloc_hider<_Alloc> _M_dataplus; 187 188 void 189 _M_data(_CharT* __p) 190 { _M_dataplus._M_p = __p; } 191 192 _Rep* 193 _M_rep() const 194 { return &((reinterpret_cast<_Rep*>(_M_data()))[-1]); } 195 196 _CharT* 197 _M_grab(const _Alloc& __alloc) const 198 { 199 return (!_M_is_leaked() && _M_get_allocator() == __alloc) 200 ? _M_rep()->_M_refcopy() : _M_rep()->_M_clone(__alloc); 201 } 202 203 void 204 _M_dispose() 205 { 206 // Be race-detector-friendly. For more info see bits/c++config. 207 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_rep()->_M_info. 208 _M_refcount); 209 if (__exchange_and_add_dispatch(&_M_rep()->_M_info._M_refcount, 210 -1) <= 0) 211 { 212 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_rep()->_M_info. 213 _M_refcount); 214 _M_rep()->_M_destroy(_M_get_allocator()); 215 } 216 } // XXX MT 217 218 bool 219 _M_is_leaked() const 220 { return _M_rep()->_M_info._M_refcount < 0; } 221 222 void 223 _M_set_sharable() 224 { _M_rep()->_M_info._M_refcount = 0; } 225 226 void 227 _M_leak_hard(); 228 229 // _S_construct_aux is used to implement the 21.3.1 para 15 which 230 // requires special behaviour if _InIterator is an integral type 231 template<typename _InIterator> 232 static _CharT* 233 _S_construct_aux(_InIterator __beg, _InIterator __end, 234 const _Alloc& __a, std::__false_type) 235 { 236 typedef typename std::iterator_traits<_InIterator>::iterator_category 237 _Tag; 238 return _S_construct(__beg, __end, __a, _Tag()); 239 } 240 241 // _GLIBCXX_RESOLVE_LIB_DEFECTS 242 // 438. Ambiguity in the "do the right thing" clause 243 template<typename _Integer> 244 static _CharT* 245 _S_construct_aux(_Integer __beg, _Integer __end, 246 const _Alloc& __a, std::__true_type) 247 { return _S_construct_aux_2(static_cast<size_type>(__beg), 248 __end, __a); } 249 250 static _CharT* 251 _S_construct_aux_2(size_type __req, _CharT __c, const _Alloc& __a) 252 { return _S_construct(__req, __c, __a); } 253 254 template<typename _InIterator> 255 static _CharT* 256 _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a) 257 { 258 typedef typename std::__is_integer<_InIterator>::__type _Integral; 259 return _S_construct_aux(__beg, __end, __a, _Integral()); 260 } 261 262 // For Input Iterators, used in istreambuf_iterators, etc. 263 template<typename _InIterator> 264 static _CharT* 265 _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a, 266 std::input_iterator_tag); 267 268 // For forward_iterators up to random_access_iterators, used for 269 // string::iterator, _CharT*, etc. 270 template<typename _FwdIterator> 271 static _CharT* 272 _S_construct(_FwdIterator __beg, _FwdIterator __end, const _Alloc& __a, 273 std::forward_iterator_tag); 274 275 static _CharT* 276 _S_construct(size_type __req, _CharT __c, const _Alloc& __a); 277 278 public: 279 size_type 280 _M_max_size() const 281 { return size_type(_S_max_size); } 282 283 _CharT* 284 _M_data() const 285 { return _M_dataplus._M_p; } 286 287 size_type 288 _M_length() const 289 { return _M_rep()->_M_info._M_length; } 290 291 size_type 292 _M_capacity() const 293 { return _M_rep()->_M_info._M_capacity; } 294 295 bool 296 _M_is_shared() const 297 { return _M_rep()->_M_info._M_refcount > 0; } 298 299 void 300 _M_set_leaked() 301 { _M_rep()->_M_info._M_refcount = -1; } 302 303 void 304 _M_leak() // for use in begin() & non-const op[] 305 { 306 if (!_M_is_leaked()) 307 _M_leak_hard(); 308 } 309 310 void 311 _M_set_length(size_type __n) 312 { _M_rep()->_M_set_length(__n); } 313 314 __rc_string_base() 315 : _M_dataplus(_S_empty_rep._M_refcopy()) { } 316 317 __rc_string_base(const _Alloc& __a); 318 319 __rc_string_base(const __rc_string_base& __rcs); 320 321 #if __cplusplus >= 201103L 322 __rc_string_base(__rc_string_base&& __rcs) 323 : _M_dataplus(__rcs._M_dataplus) 324 { __rcs._M_data(_S_empty_rep._M_refcopy()); } 325 #endif 326 327 __rc_string_base(size_type __n, _CharT __c, const _Alloc& __a); 328 329 template<typename _InputIterator> 330 __rc_string_base(_InputIterator __beg, _InputIterator __end, 331 const _Alloc& __a); 332 333 ~__rc_string_base() 334 { _M_dispose(); } 335 336 allocator_type& 337 _M_get_allocator() 338 { return _M_dataplus; } 339 340 const allocator_type& 341 _M_get_allocator() const 342 { return _M_dataplus; } 343 344 void 345 _M_swap(__rc_string_base& __rcs); 346 347 void 348 _M_assign(const __rc_string_base& __rcs); 349 350 void 351 _M_reserve(size_type __res); 352 353 void 354 _M_mutate(size_type __pos, size_type __len1, const _CharT* __s, 355 size_type __len2); 356 357 void 358 _M_erase(size_type __pos, size_type __n); 359 360 void 361 _M_clear() 362 { 363 _M_dispose(); 364 _M_data(_S_empty_rep._M_refcopy()); 365 } 366 367 bool 368 _M_compare(const __rc_string_base&) const 369 { return false; } 370 }; 371 372 template<typename _CharT, typename _Traits, typename _Alloc> 373 typename __rc_string_base<_CharT, _Traits, _Alloc>::_Rep_empty 374 __rc_string_base<_CharT, _Traits, _Alloc>::_S_empty_rep; 375 376 template<typename _CharT, typename _Traits, typename _Alloc> 377 typename __rc_string_base<_CharT, _Traits, _Alloc>::_Rep* 378 __rc_string_base<_CharT, _Traits, _Alloc>::_Rep:: 379 _S_create(size_type __capacity, size_type __old_capacity, 380 const _Alloc& __alloc) 381 { 382 // _GLIBCXX_RESOLVE_LIB_DEFECTS 383 // 83. String::npos vs. string::max_size() 384 if (__capacity > size_type(_S_max_size)) 385 std::__throw_length_error(__N("__rc_string_base::_Rep::_S_create")); 386 387 // The standard places no restriction on allocating more memory 388 // than is strictly needed within this layer at the moment or as 389 // requested by an explicit application call to reserve(). 390 391 // Many malloc implementations perform quite poorly when an 392 // application attempts to allocate memory in a stepwise fashion 393 // growing each allocation size by only 1 char. Additionally, 394 // it makes little sense to allocate less linear memory than the 395 // natural blocking size of the malloc implementation. 396 // Unfortunately, we would need a somewhat low-level calculation 397 // with tuned parameters to get this perfect for any particular 398 // malloc implementation. Fortunately, generalizations about 399 // common features seen among implementations seems to suffice. 400 401 // __pagesize need not match the actual VM page size for good 402 // results in practice, thus we pick a common value on the low 403 // side. __malloc_header_size is an estimate of the amount of 404 // overhead per memory allocation (in practice seen N * sizeof 405 // (void*) where N is 0, 2 or 4). According to folklore, 406 // picking this value on the high side is better than 407 // low-balling it (especially when this algorithm is used with 408 // malloc implementations that allocate memory blocks rounded up 409 // to a size which is a power of 2). 410 const size_type __pagesize = 4096; 411 const size_type __malloc_header_size = 4 * sizeof(void*); 412 413 // The below implements an exponential growth policy, necessary to 414 // meet amortized linear time requirements of the library: see 415 // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html. 416 if (__capacity > __old_capacity && __capacity < 2 * __old_capacity) 417 { 418 __capacity = 2 * __old_capacity; 419 // Never allocate a string bigger than _S_max_size. 420 if (__capacity > size_type(_S_max_size)) 421 __capacity = size_type(_S_max_size); 422 } 423 424 // NB: Need an array of char_type[__capacity], plus a terminating 425 // null char_type() element, plus enough for the _Rep data structure, 426 // plus sizeof(_Rep) - 1 to upper round to a size multiple of 427 // sizeof(_Rep). 428 // Whew. Seemingly so needy, yet so elemental. 429 size_type __size = ((__capacity + 1) * sizeof(_CharT) 430 + 2 * sizeof(_Rep) - 1); 431 432 const size_type __adj_size = __size + __malloc_header_size; 433 if (__adj_size > __pagesize && __capacity > __old_capacity) 434 { 435 const size_type __extra = __pagesize - __adj_size % __pagesize; 436 __capacity += __extra / sizeof(_CharT); 437 if (__capacity > size_type(_S_max_size)) 438 __capacity = size_type(_S_max_size); 439 __size = (__capacity + 1) * sizeof(_CharT) + 2 * sizeof(_Rep) - 1; 440 } 441 442 // NB: Might throw, but no worries about a leak, mate: _Rep() 443 // does not throw. 444 _Rep* __place = _Rep_alloc_type(__alloc).allocate(__size / sizeof(_Rep)); 445 _Rep* __p = new (__place) _Rep; 446 __p->_M_info._M_capacity = __capacity; 447 return __p; 448 } 449 450 template<typename _CharT, typename _Traits, typename _Alloc> 451 void 452 __rc_string_base<_CharT, _Traits, _Alloc>::_Rep:: 453 _M_destroy(const _Alloc& __a) throw () 454 { 455 const size_type __size = ((_M_info._M_capacity + 1) * sizeof(_CharT) 456 + 2 * sizeof(_Rep) - 1); 457 _Rep_alloc_type(__a).deallocate(this, __size / sizeof(_Rep)); 458 } 459 460 template<typename _CharT, typename _Traits, typename _Alloc> 461 _CharT* 462 __rc_string_base<_CharT, _Traits, _Alloc>::_Rep:: 463 _M_clone(const _Alloc& __alloc, size_type __res) 464 { 465 // Requested capacity of the clone. 466 const size_type __requested_cap = _M_info._M_length + __res; 467 _Rep* __r = _Rep::_S_create(__requested_cap, _M_info._M_capacity, 468 __alloc); 469 470 if (_M_info._M_length) 471 __rc_string_base::_S_copy(__r->_M_refdata(), _M_refdata(), _M_info._M_length); 472 473 __r->_M_set_length(_M_info._M_length); 474 return __r->_M_refdata(); 475 } 476 477 template<typename _CharT, typename _Traits, typename _Alloc> 478 __rc_string_base<_CharT, _Traits, _Alloc>:: 479 __rc_string_base(const _Alloc& __a) 480 : _M_dataplus(__a, _S_construct(size_type(), _CharT(), __a)) { } 481 482 template<typename _CharT, typename _Traits, typename _Alloc> 483 __rc_string_base<_CharT, _Traits, _Alloc>:: 484 __rc_string_base(const __rc_string_base& __rcs) 485 : _M_dataplus(__rcs._M_get_allocator(), 486 __rcs._M_grab(__rcs._M_get_allocator())) { } 487 488 template<typename _CharT, typename _Traits, typename _Alloc> 489 __rc_string_base<_CharT, _Traits, _Alloc>:: 490 __rc_string_base(size_type __n, _CharT __c, const _Alloc& __a) 491 : _M_dataplus(__a, _S_construct(__n, __c, __a)) { } 492 493 template<typename _CharT, typename _Traits, typename _Alloc> 494 template<typename _InputIterator> 495 __rc_string_base<_CharT, _Traits, _Alloc>:: 496 __rc_string_base(_InputIterator __beg, _InputIterator __end, 497 const _Alloc& __a) 498 : _M_dataplus(__a, _S_construct(__beg, __end, __a)) { } 499 500 template<typename _CharT, typename _Traits, typename _Alloc> 501 void 502 __rc_string_base<_CharT, _Traits, _Alloc>:: 503 _M_leak_hard() 504 { 505 if (_M_is_shared()) 506 _M_erase(0, 0); 507 _M_set_leaked(); 508 } 509 510 // NB: This is the special case for Input Iterators, used in 511 // istreambuf_iterators, etc. 512 // Input Iterators have a cost structure very different from 513 // pointers, calling for a different coding style. 514 template<typename _CharT, typename _Traits, typename _Alloc> 515 template<typename _InIterator> 516 _CharT* 517 __rc_string_base<_CharT, _Traits, _Alloc>:: 518 _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a, 519 std::input_iterator_tag) 520 { 521 if (__beg == __end && __a == _Alloc()) 522 return _S_empty_rep._M_refcopy(); 523 524 // Avoid reallocation for common case. 525 _CharT __buf[128]; 526 size_type __len = 0; 527 while (__beg != __end && __len < sizeof(__buf) / sizeof(_CharT)) 528 { 529 __buf[__len++] = *__beg; 530 ++__beg; 531 } 532 _Rep* __r = _Rep::_S_create(__len, size_type(0), __a); 533 _S_copy(__r->_M_refdata(), __buf, __len); 534 __try 535 { 536 while (__beg != __end) 537 { 538 if (__len == __r->_M_info._M_capacity) 539 { 540 // Allocate more space. 541 _Rep* __another = _Rep::_S_create(__len + 1, __len, __a); 542 _S_copy(__another->_M_refdata(), __r->_M_refdata(), __len); 543 __r->_M_destroy(__a); 544 __r = __another; 545 } 546 __r->_M_refdata()[__len++] = *__beg; 547 ++__beg; 548 } 549 } 550 __catch(...) 551 { 552 __r->_M_destroy(__a); 553 __throw_exception_again; 554 } 555 __r->_M_set_length(__len); 556 return __r->_M_refdata(); 557 } 558 559 template<typename _CharT, typename _Traits, typename _Alloc> 560 template<typename _InIterator> 561 _CharT* 562 __rc_string_base<_CharT, _Traits, _Alloc>:: 563 _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a, 564 std::forward_iterator_tag) 565 { 566 if (__beg == __end && __a == _Alloc()) 567 return _S_empty_rep._M_refcopy(); 568 569 // NB: Not required, but considered best practice. 570 if (__is_null_pointer(__beg) && __beg != __end) 571 std::__throw_logic_error(__N("__rc_string_base::" 572 "_S_construct null not valid")); 573 574 const size_type __dnew = static_cast<size_type>(std::distance(__beg, 575 __end)); 576 // Check for out_of_range and length_error exceptions. 577 _Rep* __r = _Rep::_S_create(__dnew, size_type(0), __a); 578 __try 579 { __rc_string_base::_S_copy_chars(__r->_M_refdata(), __beg, __end); } 580 __catch(...) 581 { 582 __r->_M_destroy(__a); 583 __throw_exception_again; 584 } 585 __r->_M_set_length(__dnew); 586 return __r->_M_refdata(); 587 } 588 589 template<typename _CharT, typename _Traits, typename _Alloc> 590 _CharT* 591 __rc_string_base<_CharT, _Traits, _Alloc>:: 592 _S_construct(size_type __n, _CharT __c, const _Alloc& __a) 593 { 594 if (__n == 0 && __a == _Alloc()) 595 return _S_empty_rep._M_refcopy(); 596 597 // Check for out_of_range and length_error exceptions. 598 _Rep* __r = _Rep::_S_create(__n, size_type(0), __a); 599 if (__n) 600 __rc_string_base::_S_assign(__r->_M_refdata(), __n, __c); 601 602 __r->_M_set_length(__n); 603 return __r->_M_refdata(); 604 } 605 606 template<typename _CharT, typename _Traits, typename _Alloc> 607 void 608 __rc_string_base<_CharT, _Traits, _Alloc>:: 609 _M_swap(__rc_string_base& __rcs) 610 { 611 if (_M_is_leaked()) 612 _M_set_sharable(); 613 if (__rcs._M_is_leaked()) 614 __rcs._M_set_sharable(); 615 616 _CharT* __tmp = _M_data(); 617 _M_data(__rcs._M_data()); 618 __rcs._M_data(__tmp); 619 620 // _GLIBCXX_RESOLVE_LIB_DEFECTS 621 // 431. Swapping containers with unequal allocators. 622 std::__alloc_swap<allocator_type>::_S_do_it(_M_get_allocator(), 623 __rcs._M_get_allocator()); 624 } 625 626 template<typename _CharT, typename _Traits, typename _Alloc> 627 void 628 __rc_string_base<_CharT, _Traits, _Alloc>:: 629 _M_assign(const __rc_string_base& __rcs) 630 { 631 if (_M_rep() != __rcs._M_rep()) 632 { 633 _CharT* __tmp = __rcs._M_grab(_M_get_allocator()); 634 _M_dispose(); 635 _M_data(__tmp); 636 } 637 } 638 639 template<typename _CharT, typename _Traits, typename _Alloc> 640 void 641 __rc_string_base<_CharT, _Traits, _Alloc>:: 642 _M_reserve(size_type __res) 643 { 644 // Make sure we don't shrink below the current size. 645 if (__res < _M_length()) 646 __res = _M_length(); 647 648 if (__res != _M_capacity() || _M_is_shared()) 649 { 650 _CharT* __tmp = _M_rep()->_M_clone(_M_get_allocator(), 651 __res - _M_length()); 652 _M_dispose(); 653 _M_data(__tmp); 654 } 655 } 656 657 template<typename _CharT, typename _Traits, typename _Alloc> 658 void 659 __rc_string_base<_CharT, _Traits, _Alloc>:: 660 _M_mutate(size_type __pos, size_type __len1, const _CharT* __s, 661 size_type __len2) 662 { 663 const size_type __how_much = _M_length() - __pos - __len1; 664 665 _Rep* __r = _Rep::_S_create(_M_length() + __len2 - __len1, 666 _M_capacity(), _M_get_allocator()); 667 668 if (__pos) 669 this->_S_copy(__r->_M_refdata(), _M_data(), __pos); 670 if (__s && __len2) 671 this->_S_copy(__r->_M_refdata() + __pos, __s, __len2); 672 if (__how_much) 673 this->_S_copy(__r->_M_refdata() + __pos + __len2, 674 _M_data() + __pos + __len1, __how_much); 675 676 _M_dispose(); 677 _M_data(__r->_M_refdata()); 678 } 679 680 template<typename _CharT, typename _Traits, typename _Alloc> 681 void 682 __rc_string_base<_CharT, _Traits, _Alloc>:: 683 _M_erase(size_type __pos, size_type __n) 684 { 685 const size_type __new_size = _M_length() - __n; 686 const size_type __how_much = _M_length() - __pos - __n; 687 688 if (_M_is_shared()) 689 { 690 // Must reallocate. 691 _Rep* __r = _Rep::_S_create(__new_size, _M_capacity(), 692 _M_get_allocator()); 693 694 if (__pos) 695 this->_S_copy(__r->_M_refdata(), _M_data(), __pos); 696 if (__how_much) 697 this->_S_copy(__r->_M_refdata() + __pos, 698 _M_data() + __pos + __n, __how_much); 699 700 _M_dispose(); 701 _M_data(__r->_M_refdata()); 702 } 703 else if (__how_much && __n) 704 { 705 // Work in-place. 706 this->_S_move(_M_data() + __pos, 707 _M_data() + __pos + __n, __how_much); 708 } 709 710 _M_rep()->_M_set_length(__new_size); 711 } 712 713 template<> 714 inline bool 715 __rc_string_base<char, std::char_traits<char>, 716 std::allocator<char> >:: 717 _M_compare(const __rc_string_base& __rcs) const 718 { 719 if (_M_rep() == __rcs._M_rep()) 720 return true; 721 return false; 722 } 723 724 template<> 725 inline bool 726 __rc_string_base<wchar_t, std::char_traits<wchar_t>, 727 std::allocator<wchar_t> >:: 728 _M_compare(const __rc_string_base& __rcs) const 729 { 730 if (_M_rep() == __rcs._M_rep()) 731 return true; 732 return false; 733 } 734 735 _GLIBCXX_END_NAMESPACE_VERSION 736 } // namespace 737 738 #endif /* _RC_STRING_BASE_H */
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