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

   1 // Short-string-optimized versatile string base -*- C++ -*-
   2
   3 // Copyright (C) 2005, 2006, 2007, 2008, 2009 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 file is a GNU extension to the Standard C++ Library.
  27  *  This is an internal header file, included by other library headers.
  28  *  You should not attempt to use it directly.
  29  */
  30
  31 #ifndef _SSO_STRING_BASE_H
  32 #define _SSO_STRING_BASE_H 1
  33
  34 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  35
  36   template<typename _CharT, typename _Traits, typename _Alloc>
  37     class __sso_string_base
  38     : protected __vstring_utility<_CharT, _Traits, _Alloc>
  39     {
  40     public:
  41       typedef _Traits                                       traits_type;
  42       typedef typename _Traits::char_type                   value_type;
  43
  44       typedef __vstring_utility<_CharT, _Traits, _Alloc>    _Util_Base;
  45       typedef typename _Util_Base::_CharT_alloc_type        _CharT_alloc_type;
  46       typedef typename _CharT_alloc_type::size_type         size_type;
  47
  48     private:
  49       // Data Members:
  50       typename _Util_Base::template _Alloc_hider<_CharT_alloc_type>
  51                                                             _M_dataplus;
  52       size_type                                             _M_string_length;
  53
  54       enum { _S_local_capacity = 15 };
  55
  56       union
  57       {
  58         _CharT           _M_local_data[_S_local_capacity + 1];
  59         size_type        _M_allocated_capacity;
  60       };
  61
  62       void
  63       _M_data(_CharT* __p)
  64       { _M_dataplus._M_p = __p; }
  65
  66       void
  67       _M_length(size_type __length)
  68       { _M_string_length = __length; }
  69
  70       void
  71       _M_capacity(size_type __capacity)
  72       { _M_allocated_capacity = __capacity; }
  73
  74       bool
  75       _M_is_local() const
  76       { return _M_data() == _M_local_data; }
  77
  78       // Create & Destroy
  79       _CharT*
  80       _M_create(size_type&, size_type);
  81
  82       void
  83       _M_dispose()
  84       {
  85         if (!_M_is_local())
  86           _M_destroy(_M_allocated_capacity);
  87       }
  88
  89       void
  90       _M_destroy(size_type __size) throw()
  91       { _M_get_allocator().deallocate(_M_data(), __size + 1); }
  92
  93       // _M_construct_aux is used to implement the 21.3.1 para 15 which
  94       // requires special behaviour if _InIterator is an integral type
  95       template<typename _InIterator>
  96         void
  97         _M_construct_aux(_InIterator __beg, _InIterator __end,
  98                          std::__false_type)
  99         {
 100           typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
 101           _M_construct(__beg, __end, _Tag());
 102         }
 103
 104       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 105       // 438. Ambiguity in the "do the right thing" clause
 106       template<typename _Integer>
 107         void
 108         _M_construct_aux(_Integer __beg, _Integer __end, std::__true_type)
 109         { _M_construct_aux_2(static_cast<size_type>(__beg), __end); }
 110
 111       void
 112       _M_construct_aux_2(size_type __req, _CharT __c)
 113       { _M_construct(__req, __c); }
 114
 115       template<typename _InIterator>
 116         void
 117         _M_construct(_InIterator __beg, _InIterator __end)
 118         {
 119           typedef typename std::__is_integer<_InIterator>::__type _Integral;
 120           _M_construct_aux(__beg, __end, _Integral());
 121         }
 122
 123       // For Input Iterators, used in istreambuf_iterators, etc.
 124       template<typename _InIterator>
 125         void
 126         _M_construct(_InIterator __beg, _InIterator __end,
 127                      std::input_iterator_tag);
 128
 129       // For forward_iterators up to random_access_iterators, used for
 130       // string::iterator, _CharT*, etc.
 131       template<typename _FwdIterator>
 132         void
 133         _M_construct(_FwdIterator __beg, _FwdIterator __end,
 134                      std::forward_iterator_tag);
 135
 136       void
 137       _M_construct(size_type __req, _CharT __c);
 138
 139     public:
 140       size_type
 141       _M_max_size() const
 142       { return (_M_get_allocator().max_size() - 1) / 2; }
 143
 144       _CharT*
 145       _M_data() const
 146       { return _M_dataplus._M_p; }
 147
 148       size_type
 149       _M_length() const
 150       { return _M_string_length; }
 151
 152       size_type
 153       _M_capacity() const
 154       {
 155         return _M_is_local() ? size_type(_S_local_capacity)
 156                              : _M_allocated_capacity;
 157       }
 158
 159       bool
 160       _M_is_shared() const
 161       { return false; }
 162
 163       void
 164       _M_set_leaked() { }
 165
 166       void
 167       _M_leak() { }
 168
 169       void
 170       _M_set_length(size_type __n)
 171       {
 172         _M_length(__n);
 173         traits_type::assign(_M_data()[__n], _CharT());
 174       }
 175
 176       __sso_string_base()
 177       : _M_dataplus(_M_local_data)
 178       { _M_set_length(0); }
 179
 180       __sso_string_base(const _Alloc& __a);
 181
 182       __sso_string_base(const __sso_string_base& __rcs);
 183
 184 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 185       __sso_string_base(__sso_string_base&& __rcs);
 186 #endif
 187
 188       __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a);
 189
 190       template<typename _InputIterator>
 191         __sso_string_base(_InputIterator __beg, _InputIterator __end,
 192                           const _Alloc& __a);
 193
 194       ~__sso_string_base()
 195       { _M_dispose(); }
 196
 197       _CharT_alloc_type&
 198       _M_get_allocator()
 199       { return _M_dataplus; }
 200
 201       const _CharT_alloc_type&
 202       _M_get_allocator() const
 203       { return _M_dataplus; }
 204
 205       void
 206       _M_swap(__sso_string_base& __rcs);
 207
 208       void
 209       _M_assign(const __sso_string_base& __rcs);
 210
 211       void
 212       _M_reserve(size_type __res);
 213
 214       void
 215       _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 216                 size_type __len2);
 217
 218       void
 219       _M_erase(size_type __pos, size_type __n);
 220
 221       void
 222       _M_clear()
 223       { _M_set_length(0); }
 224
 225       bool
 226       _M_compare(const __sso_string_base&) const
 227       { return false; }
 228     };
 229
 230   template<typename _CharT, typename _Traits, typename _Alloc>
 231     void
 232     __sso_string_base<_CharT, _Traits, _Alloc>::
 233     _M_swap(__sso_string_base& __rcs)
 234     {
 235       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 236       // 431. Swapping containers with unequal allocators.
 237       std::__alloc_swap<_CharT_alloc_type>::_S_do_it(_M_get_allocator(),
 238                                                      __rcs._M_get_allocator());
 239
 240       if (_M_is_local())
 241         if (__rcs._M_is_local())
 242           {
 243             if (_M_length() && __rcs._M_length())
 244               {
 245                 _CharT __tmp_data[_S_local_capacity + 1];
 246                 traits_type::copy(__tmp_data, __rcs._M_local_data,
 247                                   _S_local_capacity + 1);
 248                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 249                                   _S_local_capacity + 1);
 250                 traits_type::copy(_M_local_data, __tmp_data,
 251                                   _S_local_capacity + 1);
 252               }
 253             else if (__rcs._M_length())
 254               {
 255                 traits_type::copy(_M_local_data, __rcs._M_local_data,
 256                                   _S_local_capacity + 1);
 257                 _M_length(__rcs._M_length());
 258                 __rcs._M_set_length(0);
 259                 return;
 260               }
 261             else if (_M_length())
 262               {
 263                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 264                                   _S_local_capacity + 1);
 265                 __rcs._M_length(_M_length());
 266                 _M_set_length(0);
 267                 return;
 268               }
 269           }
 270         else
 271           {
 272             const size_type __tmp_capacity = __rcs._M_allocated_capacity;
 273             traits_type::copy(__rcs._M_local_data, _M_local_data,
 274                               _S_local_capacity + 1);
 275             _M_data(__rcs._M_data());
 276             __rcs._M_data(__rcs._M_local_data);
 277             _M_capacity(__tmp_capacity);
 278           }
 279       else
 280         {
 281           const size_type __tmp_capacity = _M_allocated_capacity;
 282           if (__rcs._M_is_local())
 283             {
 284               traits_type::copy(_M_local_data, __rcs._M_local_data,
 285                                 _S_local_capacity + 1);
 286               __rcs._M_data(_M_data());
 287               _M_data(_M_local_data);
 288             }
 289           else
 290             {
 291               _CharT* __tmp_ptr = _M_data();
 292               _M_data(__rcs._M_data());
 293               __rcs._M_data(__tmp_ptr);
 294               _M_capacity(__rcs._M_allocated_capacity);
 295             }
 296           __rcs._M_capacity(__tmp_capacity);
 297         }
 298
 299       const size_type __tmp_length = _M_length();
 300       _M_length(__rcs._M_length());
 301       __rcs._M_length(__tmp_length);
 302     }
 303
 304   template<typename _CharT, typename _Traits, typename _Alloc>
 305     _CharT*
 306     __sso_string_base<_CharT, _Traits, _Alloc>::
 307     _M_create(size_type& __capacity, size_type __old_capacity)
 308     {
 309       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 310       // 83.  String::npos vs. string::max_size()
 311       if (__capacity > _M_max_size())
 312         std::__throw_length_error(__N("__sso_string_base::_M_create"));
 313
 314       // The below implements an exponential growth policy, necessary to
 315       // meet amortized linear time requirements of the library: see
 316       // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
 317       if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
 318         {
 319           __capacity = 2 * __old_capacity;
 320           // Never allocate a string bigger than max_size.
 321           if (__capacity > _M_max_size())
 322             __capacity = _M_max_size();
 323         }
 324
 325       // NB: Need an array of char_type[__capacity], plus a terminating
 326       // null char_type() element.
 327       return _M_get_allocator().allocate(__capacity + 1);
 328     }
 329
 330   template<typename _CharT, typename _Traits, typename _Alloc>
 331     __sso_string_base<_CharT, _Traits, _Alloc>::
 332     __sso_string_base(const _Alloc& __a)
 333     : _M_dataplus(__a, _M_local_data)
 334     { _M_set_length(0); }
 335
 336   template<typename _CharT, typename _Traits, typename _Alloc>
 337     __sso_string_base<_CharT, _Traits, _Alloc>::
 338     __sso_string_base(const __sso_string_base& __rcs)
 339     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
 340     { _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
 341
 342 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 343   template<typename _CharT, typename _Traits, typename _Alloc>
 344     __sso_string_base<_CharT, _Traits, _Alloc>::
 345     __sso_string_base(__sso_string_base&& __rcs)
 346     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
 347     {
 348       if (__rcs._M_is_local())
 349         {
 350           if (__rcs._M_length())
 351             traits_type::copy(_M_local_data, __rcs._M_local_data,
 352                               _S_local_capacity + 1);
 353         }
 354       else
 355         {
 356           _M_data(__rcs._M_data());
 357           _M_capacity(__rcs._M_allocated_capacity);
 358         }
 359
 360       _M_length(__rcs._M_length());
 361       __rcs._M_length(0);
 362       __rcs._M_data(__rcs._M_local_data);
 363     }
 364 #endif
 365
 366   template<typename _CharT, typename _Traits, typename _Alloc>
 367     __sso_string_base<_CharT, _Traits, _Alloc>::
 368     __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
 369     : _M_dataplus(__a, _M_local_data)
 370     { _M_construct(__n, __c); }
 371
 372   template<typename _CharT, typename _Traits, typename _Alloc>
 373     template<typename _InputIterator>
 374     __sso_string_base<_CharT, _Traits, _Alloc>::
 375     __sso_string_base(_InputIterator __beg, _InputIterator __end,
 376                       const _Alloc& __a)
 377     : _M_dataplus(__a, _M_local_data)
 378     { _M_construct(__beg, __end); }
 379
 380   // NB: This is the special case for Input Iterators, used in
 381   // istreambuf_iterators, etc.
 382   // Input Iterators have a cost structure very different from
 383   // pointers, calling for a different coding style.
 384   template<typename _CharT, typename _Traits, typename _Alloc>
 385     template<typename _InIterator>
 386       void
 387       __sso_string_base<_CharT, _Traits, _Alloc>::
 388       _M_construct(_InIterator __beg, _InIterator __end,
 389                    std::input_iterator_tag)
 390       {
 391         size_type __len = 0;
 392         size_type __capacity = size_type(_S_local_capacity);
 393
 394         while (__beg != __end && __len < __capacity)
 395           {
 396             _M_data()[__len++] = *__beg;
 397             ++__beg;
 398           }
 399
 400         __try
 401           {
 402             while (__beg != __end)
 403               {
 404                 if (__len == __capacity)
 405                   {
 406                     // Allocate more space.
 407                     __capacity = __len + 1;
 408                     _CharT* __another = _M_create(__capacity, __len);
 409                     _S_copy(__another, _M_data(), __len);
 410                     _M_dispose();
 411                     _M_data(__another);
 412                     _M_capacity(__capacity);
 413                   }
 414                 _M_data()[__len++] = *__beg;
 415                 ++__beg;
 416               }
 417           }
 418         __catch(...)
 419           {
 420             _M_dispose();
 421             __throw_exception_again;
 422           }
 423
 424         _M_set_length(__len);
 425       }
 426
 427   template<typename _CharT, typename _Traits, typename _Alloc>
 428     template<typename _InIterator>
 429       void
 430       __sso_string_base<_CharT, _Traits, _Alloc>::
 431       _M_construct(_InIterator __beg, _InIterator __end,
 432                    std::forward_iterator_tag)
 433       {
 434         // NB: Not required, but considered best practice.
 435         if (__is_null_pointer(__beg) && __beg != __end)
 436           std::__throw_logic_error(__N("__sso_string_base::"
 437                                        "_M_construct null not valid"));
 438
 439         size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
 440
 441         if (__dnew > size_type(_S_local_capacity))
 442           {
 443             _M_data(_M_create(__dnew, size_type(0)));
 444             _M_capacity(__dnew);
 445           }
 446
 447         // Check for out_of_range and length_error exceptions.
 448         __try
 449           { _S_copy_chars(_M_data(), __beg, __end); }
 450         __catch(...)
 451           {
 452             _M_dispose();
 453             __throw_exception_again;
 454           }
 455
 456         _M_set_length(__dnew);
 457       }
 458
 459   template<typename _CharT, typename _Traits, typename _Alloc>
 460     void
 461     __sso_string_base<_CharT, _Traits, _Alloc>::
 462     _M_construct(size_type __n, _CharT __c)
 463     {
 464       if (__n > size_type(_S_local_capacity))
 465         {
 466           _M_data(_M_create(__n, size_type(0)));
 467           _M_capacity(__n);
 468         }
 469
 470       if (__n)
 471         _S_assign(_M_data(), __n, __c);
 472
 473       _M_set_length(__n);
 474     }
 475
 476   template<typename _CharT, typename _Traits, typename _Alloc>
 477     void
 478     __sso_string_base<_CharT, _Traits, _Alloc>::
 479     _M_assign(const __sso_string_base& __rcs)
 480     {
 481       if (this != &__rcs)
 482         {
 483           const size_type __rsize = __rcs._M_length();
 484           const size_type __capacity = _M_capacity();
 485
 486           if (__rsize > __capacity)
 487             {
 488               size_type __new_capacity = __rsize;
 489               _CharT* __tmp = _M_create(__new_capacity, __capacity);
 490               _M_dispose();
 491               _M_data(__tmp);
 492               _M_capacity(__new_capacity);
 493             }
 494
 495           if (__rsize)
 496             _S_copy(_M_data(), __rcs._M_data(), __rsize);
 497
 498           _M_set_length(__rsize);
 499         }
 500     }
 501
 502   template<typename _CharT, typename _Traits, typename _Alloc>
 503     void
 504     __sso_string_base<_CharT, _Traits, _Alloc>::
 505     _M_reserve(size_type __res)
 506     {
 507       // Make sure we don't shrink below the current size.
 508       if (__res < _M_length())
 509         __res = _M_length();
 510
 511       const size_type __capacity = _M_capacity();
 512       if (__res != __capacity)
 513         {
 514           if (__res > __capacity
 515               || __res > size_type(_S_local_capacity))
 516             {
 517               _CharT* __tmp = _M_create(__res, __capacity);
 518               _S_copy(__tmp, _M_data(), _M_length() + 1);
 519               _M_dispose();
 520               _M_data(__tmp);
 521               _M_capacity(__res);
 522             }
 523           else if (!_M_is_local())
 524             {
 525               _S_copy(_M_local_data, _M_data(), _M_length() + 1);
 526               _M_destroy(__capacity);
 527               _M_data(_M_local_data);
 528             }
 529         }
 530     }
 531
 532   template<typename _CharT, typename _Traits, typename _Alloc>
 533     void
 534     __sso_string_base<_CharT, _Traits, _Alloc>::
 535     _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 536               size_type __len2)
 537     {
 538       const size_type __how_much = _M_length() - __pos - __len1;
 539
 540       size_type __new_capacity = _M_length() + __len2 - __len1;
 541       _CharT* __r = _M_create(__new_capacity, _M_capacity());
 542
 543       if (__pos)
 544         _S_copy(__r, _M_data(), __pos);
 545       if (__s && __len2)
 546         _S_copy(__r + __pos, __s, __len2);
 547       if (__how_much)
 548         _S_copy(__r + __pos + __len2,
 549                 _M_data() + __pos + __len1, __how_much);
 550
 551       _M_dispose();
 552       _M_data(__r);
 553       _M_capacity(__new_capacity);
 554     }
 555
 556   template<typename _CharT, typename _Traits, typename _Alloc>
 557     void
 558     __sso_string_base<_CharT, _Traits, _Alloc>::
 559     _M_erase(size_type __pos, size_type __n)
 560     {
 561       const size_type __how_much = _M_length() - __pos - __n;
 562
 563       if (__how_much && __n)
 564         _S_move(_M_data() + __pos, _M_data() + __pos + __n,
 565                 __how_much);
 566
 567       _M_set_length(_M_length() - __n);
 568     }
 569
 570 _GLIBCXX_END_NAMESPACE
 571
 572 #endif /* _SSO_STRING_BASE_H */