libstdc++-v3/include/ext/sso_string_base.h

   1 // Short-string-optimized versatile string base -*- C++ -*-
   2
   3 // Copyright (C) 2005-2014 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/sso_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 _SSO_STRING_BASE_H
  31 #define _SSO_STRING_BASE_H 1
  32
  33 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
  34 {
  35 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  36
  37   template<typename _CharT, typename _Traits, typename _Alloc>
  38     class __sso_string_base
  39     : protected __vstring_utility<_CharT, _Traits, _Alloc>
  40     {
  41     public:
  42       typedef _Traits                                       traits_type;
  43       typedef typename _Traits::char_type                   value_type;
  44
  45       typedef __vstring_utility<_CharT, _Traits, _Alloc>    _Util_Base;
  46       typedef typename _Util_Base::_CharT_alloc_type        _CharT_alloc_type;
  47       typedef typename _CharT_alloc_type::size_type         size_type;
  48
  49     private:
  50       // Data Members:
  51       typename _Util_Base::template _Alloc_hider<_CharT_alloc_type>
  52                                                             _M_dataplus;
  53       size_type                                             _M_string_length;
  54
  55       enum { _S_local_capacity = 15 };
  56
  57       union
  58       {
  59         _CharT           _M_local_data[_S_local_capacity + 1];
  60         size_type        _M_allocated_capacity;
  61       };
  62
  63       void
  64       _M_data(_CharT* __p)
  65       { _M_dataplus._M_p = __p; }
  66
  67       void
  68       _M_length(size_type __length)
  69       { _M_string_length = __length; }
  70
  71       void
  72       _M_capacity(size_type __capacity)
  73       { _M_allocated_capacity = __capacity; }
  74
  75       bool
  76       _M_is_local() const
  77       { return _M_data() == _M_local_data; }
  78
  79       // Create & Destroy
  80       _CharT*
  81       _M_create(size_type&, size_type);
  82
  83       void
  84       _M_dispose()
  85       {
  86         if (!_M_is_local())
  87           _M_destroy(_M_allocated_capacity);
  88       }
  89
  90       void
  91       _M_destroy(size_type __size) throw()
  92       { _M_get_allocator().deallocate(_M_data(), __size + 1); }
  93
  94       // _M_construct_aux is used to implement the 21.3.1 para 15 which
  95       // requires special behaviour if _InIterator is an integral type
  96       template<typename _InIterator>
  97         void
  98         _M_construct_aux(_InIterator __beg, _InIterator __end,
  99                          std::__false_type)
 100         {
 101           typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
 102           _M_construct(__beg, __end, _Tag());
 103         }
 104
 105       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 106       // 438. Ambiguity in the "do the right thing" clause
 107       template<typename _Integer>
 108         void
 109         _M_construct_aux(_Integer __beg, _Integer __end, std::__true_type)
 110         { _M_construct_aux_2(static_cast<size_type>(__beg), __end); }
 111
 112       void
 113       _M_construct_aux_2(size_type __req, _CharT __c)
 114       { _M_construct(__req, __c); }
 115
 116       template<typename _InIterator>
 117         void
 118         _M_construct(_InIterator __beg, _InIterator __end)
 119         {
 120           typedef typename std::__is_integer<_InIterator>::__type _Integral;
 121           _M_construct_aux(__beg, __end, _Integral());
 122         }
 123
 124       // For Input Iterators, used in istreambuf_iterators, etc.
 125       template<typename _InIterator>
 126         void
 127         _M_construct(_InIterator __beg, _InIterator __end,
 128                      std::input_iterator_tag);
 129
 130       // For forward_iterators up to random_access_iterators, used for
 131       // string::iterator, _CharT*, etc.
 132       template<typename _FwdIterator>
 133         void
 134         _M_construct(_FwdIterator __beg, _FwdIterator __end,
 135                      std::forward_iterator_tag);
 136
 137       void
 138       _M_construct(size_type __req, _CharT __c);
 139
 140     public:
 141       size_type
 142       _M_max_size() const
 143       { return (_M_get_allocator().max_size() - 1) / 2; }
 144
 145       _CharT*
 146       _M_data() const
 147       { return _M_dataplus._M_p; }
 148
 149       size_type
 150       _M_length() const
 151       { return _M_string_length; }
 152
 153       size_type
 154       _M_capacity() const
 155       {
 156         return _M_is_local() ? size_type(_S_local_capacity)
 157                              : _M_allocated_capacity;
 158       }
 159
 160       bool
 161       _M_is_shared() const
 162       { return false; }
 163
 164       void
 165       _M_set_leaked() { }
 166
 167       void
 168       _M_leak() { }
 169
 170       void
 171       _M_set_length(size_type __n)
 172       {
 173         _M_length(__n);
 174         traits_type::assign(_M_data()[__n], _CharT());
 175       }
 176
 177       __sso_string_base()
 178       : _M_dataplus(_M_local_data)
 179       { _M_set_length(0); }
 180
 181       __sso_string_base(const _Alloc& __a);
 182
 183       __sso_string_base(const __sso_string_base& __rcs);
 184
 185 #if __cplusplus >= 201103L
 186       __sso_string_base(__sso_string_base&& __rcs);
 187 #endif
 188
 189       __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a);
 190
 191       template<typename _InputIterator>
 192         __sso_string_base(_InputIterator __beg, _InputIterator __end,
 193                           const _Alloc& __a);
 194
 195       ~__sso_string_base()
 196       { _M_dispose(); }
 197
 198       _CharT_alloc_type&
 199       _M_get_allocator()
 200       { return _M_dataplus; }
 201
 202       const _CharT_alloc_type&
 203       _M_get_allocator() const
 204       { return _M_dataplus; }
 205
 206       void
 207       _M_swap(__sso_string_base& __rcs);
 208
 209       void
 210       _M_assign(const __sso_string_base& __rcs);
 211
 212       void
 213       _M_reserve(size_type __res);
 214
 215       void
 216       _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 217                 size_type __len2);
 218
 219       void
 220       _M_erase(size_type __pos, size_type __n);
 221
 222       void
 223       _M_clear()
 224       { _M_set_length(0); }
 225
 226       bool
 227       _M_compare(const __sso_string_base&) const
 228       { return false; }
 229     };
 230
 231   template<typename _CharT, typename _Traits, typename _Alloc>
 232     void
 233     __sso_string_base<_CharT, _Traits, _Alloc>::
 234     _M_swap(__sso_string_base& __rcs)
 235     {
 236       if (this == &__rcs)
 237         return;
 238
 239       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 240       // 431. Swapping containers with unequal allocators.
 241       std::__alloc_swap<_CharT_alloc_type>::_S_do_it(_M_get_allocator(),
 242                                                      __rcs._M_get_allocator());
 243
 244       if (_M_is_local())
 245         if (__rcs._M_is_local())
 246           {
 247             if (_M_length() && __rcs._M_length())
 248               {
 249                 _CharT __tmp_data[_S_local_capacity + 1];
 250                 traits_type::copy(__tmp_data, __rcs._M_local_data,
 251                                   _S_local_capacity + 1);
 252                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 253                                   _S_local_capacity + 1);
 254                 traits_type::copy(_M_local_data, __tmp_data,
 255                                   _S_local_capacity + 1);
 256               }
 257             else if (__rcs._M_length())
 258               {
 259                 traits_type::copy(_M_local_data, __rcs._M_local_data,
 260                                   _S_local_capacity + 1);
 261                 _M_length(__rcs._M_length());
 262                 __rcs._M_set_length(0);
 263                 return;
 264               }
 265             else if (_M_length())
 266               {
 267                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 268                                   _S_local_capacity + 1);
 269                 __rcs._M_length(_M_length());
 270                 _M_set_length(0);
 271                 return;
 272               }
 273           }
 274         else
 275           {
 276             const size_type __tmp_capacity = __rcs._M_allocated_capacity;
 277             traits_type::copy(__rcs._M_local_data, _M_local_data,
 278                               _S_local_capacity + 1);
 279             _M_data(__rcs._M_data());
 280             __rcs._M_data(__rcs._M_local_data);
 281             _M_capacity(__tmp_capacity);
 282           }
 283       else
 284         {
 285           const size_type __tmp_capacity = _M_allocated_capacity;
 286           if (__rcs._M_is_local())
 287             {
 288               traits_type::copy(_M_local_data, __rcs._M_local_data,
 289                                 _S_local_capacity + 1);
 290               __rcs._M_data(_M_data());
 291               _M_data(_M_local_data);
 292             }
 293           else
 294             {
 295               _CharT* __tmp_ptr = _M_data();
 296               _M_data(__rcs._M_data());
 297               __rcs._M_data(__tmp_ptr);
 298               _M_capacity(__rcs._M_allocated_capacity);
 299             }
 300           __rcs._M_capacity(__tmp_capacity);
 301         }
 302
 303       const size_type __tmp_length = _M_length();
 304       _M_length(__rcs._M_length());
 305       __rcs._M_length(__tmp_length);
 306     }
 307
 308   template<typename _CharT, typename _Traits, typename _Alloc>
 309     _CharT*
 310     __sso_string_base<_CharT, _Traits, _Alloc>::
 311     _M_create(size_type& __capacity, size_type __old_capacity)
 312     {
 313       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 314       // 83.  String::npos vs. string::max_size()
 315       if (__capacity > _M_max_size())
 316         std::__throw_length_error(__N("__sso_string_base::_M_create"));
 317
 318       // The below implements an exponential growth policy, necessary to
 319       // meet amortized linear time requirements of the library: see
 320       // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
 321       if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
 322         {
 323           __capacity = 2 * __old_capacity;
 324           // Never allocate a string bigger than max_size.
 325           if (__capacity > _M_max_size())
 326             __capacity = _M_max_size();
 327         }
 328
 329       // NB: Need an array of char_type[__capacity], plus a terminating
 330       // null char_type() element.
 331       return _M_get_allocator().allocate(__capacity + 1);
 332     }
 333
 334   template<typename _CharT, typename _Traits, typename _Alloc>
 335     __sso_string_base<_CharT, _Traits, _Alloc>::
 336     __sso_string_base(const _Alloc& __a)
 337     : _M_dataplus(__a, _M_local_data)
 338     { _M_set_length(0); }
 339
 340   template<typename _CharT, typename _Traits, typename _Alloc>
 341     __sso_string_base<_CharT, _Traits, _Alloc>::
 342     __sso_string_base(const __sso_string_base& __rcs)
 343     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
 344     { _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
 345
 346 #if __cplusplus >= 201103L
 347   template<typename _CharT, typename _Traits, typename _Alloc>
 348     __sso_string_base<_CharT, _Traits, _Alloc>::
 349     __sso_string_base(__sso_string_base&& __rcs)
 350     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
 351     {
 352       if (__rcs._M_is_local())
 353         {
 354           if (__rcs._M_length())
 355             traits_type::copy(_M_local_data, __rcs._M_local_data,
 356                               _S_local_capacity + 1);
 357         }
 358       else
 359         {
 360           _M_data(__rcs._M_data());
 361           _M_capacity(__rcs._M_allocated_capacity);
 362         }
 363
 364       _M_set_length(__rcs._M_length());
 365       __rcs._M_data(__rcs._M_local_data);
 366       __rcs._M_set_length(0);
 367     }
 368 #endif
 369
 370   template<typename _CharT, typename _Traits, typename _Alloc>
 371     __sso_string_base<_CharT, _Traits, _Alloc>::
 372     __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
 373     : _M_dataplus(__a, _M_local_data)
 374     { _M_construct(__n, __c); }
 375
 376   template<typename _CharT, typename _Traits, typename _Alloc>
 377     template<typename _InputIterator>
 378     __sso_string_base<_CharT, _Traits, _Alloc>::
 379     __sso_string_base(_InputIterator __beg, _InputIterator __end,
 380                       const _Alloc& __a)
 381     : _M_dataplus(__a, _M_local_data)
 382     { _M_construct(__beg, __end); }
 383
 384   // NB: This is the special case for Input Iterators, used in
 385   // istreambuf_iterators, etc.
 386   // Input Iterators have a cost structure very different from
 387   // pointers, calling for a different coding style.
 388   template<typename _CharT, typename _Traits, typename _Alloc>
 389     template<typename _InIterator>
 390       void
 391       __sso_string_base<_CharT, _Traits, _Alloc>::
 392       _M_construct(_InIterator __beg, _InIterator __end,
 393                    std::input_iterator_tag)
 394       {
 395         size_type __len = 0;
 396         size_type __capacity = size_type(_S_local_capacity);
 397
 398         while (__beg != __end && __len < __capacity)
 399           {
 400             _M_data()[__len++] = *__beg;
 401             ++__beg;
 402           }
 403
 404         __try
 405           {
 406             while (__beg != __end)
 407               {
 408                 if (__len == __capacity)
 409                   {
 410                     // Allocate more space.
 411                     __capacity = __len + 1;
 412                     _CharT* __another = _M_create(__capacity, __len);
 413                     this->_S_copy(__another, _M_data(), __len);
 414                     _M_dispose();
 415                     _M_data(__another);
 416                     _M_capacity(__capacity);
 417                   }
 418                 _M_data()[__len++] = *__beg;
 419                 ++__beg;
 420               }
 421           }
 422         __catch(...)
 423           {
 424             _M_dispose();
 425             __throw_exception_again;
 426           }
 427
 428         _M_set_length(__len);
 429       }
 430
 431   template<typename _CharT, typename _Traits, typename _Alloc>
 432     template<typename _InIterator>
 433       void
 434       __sso_string_base<_CharT, _Traits, _Alloc>::
 435       _M_construct(_InIterator __beg, _InIterator __end,
 436                    std::forward_iterator_tag)
 437       {
 438         // NB: Not required, but considered best practice.
 439         if (__is_null_pointer(__beg) && __beg != __end)
 440           std::__throw_logic_error(__N("__sso_string_base::"
 441                                        "_M_construct null not valid"));
 442
 443         size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
 444
 445         if (__dnew > size_type(_S_local_capacity))
 446           {
 447             _M_data(_M_create(__dnew, size_type(0)));
 448             _M_capacity(__dnew);
 449           }
 450
 451         // Check for out_of_range and length_error exceptions.
 452         __try
 453           { this->_S_copy_chars(_M_data(), __beg, __end); }
 454         __catch(...)
 455           {
 456             _M_dispose();
 457             __throw_exception_again;
 458           }
 459
 460         _M_set_length(__dnew);
 461       }
 462
 463   template<typename _CharT, typename _Traits, typename _Alloc>
 464     void
 465     __sso_string_base<_CharT, _Traits, _Alloc>::
 466     _M_construct(size_type __n, _CharT __c)
 467     {
 468       if (__n > size_type(_S_local_capacity))
 469         {
 470           _M_data(_M_create(__n, size_type(0)));
 471           _M_capacity(__n);
 472         }
 473
 474       if (__n)
 475         this->_S_assign(_M_data(), __n, __c);
 476
 477       _M_set_length(__n);
 478     }
 479
 480   template<typename _CharT, typename _Traits, typename _Alloc>
 481     void
 482     __sso_string_base<_CharT, _Traits, _Alloc>::
 483     _M_assign(const __sso_string_base& __rcs)
 484     {
 485       if (this != &__rcs)
 486         {
 487           const size_type __rsize = __rcs._M_length();
 488           const size_type __capacity = _M_capacity();
 489
 490           if (__rsize > __capacity)
 491             {
 492               size_type __new_capacity = __rsize;
 493               _CharT* __tmp = _M_create(__new_capacity, __capacity);
 494               _M_dispose();
 495               _M_data(__tmp);
 496               _M_capacity(__new_capacity);
 497             }
 498
 499           if (__rsize)
 500             this->_S_copy(_M_data(), __rcs._M_data(), __rsize);
 501
 502           _M_set_length(__rsize);
 503         }
 504     }
 505
 506   template<typename _CharT, typename _Traits, typename _Alloc>
 507     void
 508     __sso_string_base<_CharT, _Traits, _Alloc>::
 509     _M_reserve(size_type __res)
 510     {
 511       // Make sure we don't shrink below the current size.
 512       if (__res < _M_length())
 513         __res = _M_length();
 514
 515       const size_type __capacity = _M_capacity();
 516       if (__res != __capacity)
 517         {
 518           if (__res > __capacity
 519               || __res > size_type(_S_local_capacity))
 520             {
 521               _CharT* __tmp = _M_create(__res, __capacity);
 522               this->_S_copy(__tmp, _M_data(), _M_length() + 1);
 523               _M_dispose();
 524               _M_data(__tmp);
 525               _M_capacity(__res);
 526             }
 527           else if (!_M_is_local())
 528             {
 529               this->_S_copy(_M_local_data, _M_data(), _M_length() + 1);
 530               _M_destroy(__capacity);
 531               _M_data(_M_local_data);
 532             }
 533         }
 534     }
 535
 536   template<typename _CharT, typename _Traits, typename _Alloc>
 537     void
 538     __sso_string_base<_CharT, _Traits, _Alloc>::
 539     _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 540               size_type __len2)
 541     {
 542       const size_type __how_much = _M_length() - __pos - __len1;
 543
 544       size_type __new_capacity = _M_length() + __len2 - __len1;
 545       _CharT* __r = _M_create(__new_capacity, _M_capacity());
 546
 547       if (__pos)
 548         this->_S_copy(__r, _M_data(), __pos);
 549       if (__s && __len2)
 550         this->_S_copy(__r + __pos, __s, __len2);
 551       if (__how_much)
 552         this->_S_copy(__r + __pos + __len2,
 553                       _M_data() + __pos + __len1, __how_much);
 554
 555       _M_dispose();
 556       _M_data(__r);
 557       _M_capacity(__new_capacity);
 558     }
 559
 560   template<typename _CharT, typename _Traits, typename _Alloc>
 561     void
 562     __sso_string_base<_CharT, _Traits, _Alloc>::
 563     _M_erase(size_type __pos, size_type __n)
 564     {
 565       const size_type __how_much = _M_length() - __pos - __n;
 566
 567       if (__how_much && __n)
 568         this->_S_move(_M_data() + __pos, _M_data() + __pos + __n, __how_much);
 569
 570       _M_set_length(_M_length() - __n);
 571     }
 572
 573 _GLIBCXX_END_NAMESPACE_VERSION
 574 } // namespace
 575
 576 #endif /* _SSO_STRING_BASE_H */