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, 2010
   4 // Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16
  17 // Under Section 7 of GPL version 3, you are granted additional
  18 // permissions described in the GCC Runtime Library Exception, version
  19 // 3.1, as published by the Free Software Foundation.
  20
  21 // You should have received a copy of the GNU General Public License and
  22 // a copy of the GCC Runtime Library Exception along with this program;
  23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 // <http://www.gnu.org/licenses/>.
  25
  26 /** @file ext/sso_string_base.h
  27  *  This is an internal header file, included by other library headers.
  28  *  Do not attempt to use it directly. @headername{ext/vstring.h}
  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       if (this == &__rcs)
 236         return;
 237
 238       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 239       // 431. Swapping containers with unequal allocators.
 240       std::__alloc_swap<_CharT_alloc_type>::_S_do_it(_M_get_allocator(),
 241                                                      __rcs._M_get_allocator());
 242
 243       if (_M_is_local())
 244         if (__rcs._M_is_local())
 245           {
 246             if (_M_length() && __rcs._M_length())
 247               {
 248                 _CharT __tmp_data[_S_local_capacity + 1];
 249                 traits_type::copy(__tmp_data, __rcs._M_local_data,
 250                                   _S_local_capacity + 1);
 251                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 252                                   _S_local_capacity + 1);
 253                 traits_type::copy(_M_local_data, __tmp_data,
 254                                   _S_local_capacity + 1);
 255               }
 256             else if (__rcs._M_length())
 257               {
 258                 traits_type::copy(_M_local_data, __rcs._M_local_data,
 259                                   _S_local_capacity + 1);
 260                 _M_length(__rcs._M_length());
 261                 __rcs._M_set_length(0);
 262                 return;
 263               }
 264             else if (_M_length())
 265               {
 266                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 267                                   _S_local_capacity + 1);
 268                 __rcs._M_length(_M_length());
 269                 _M_set_length(0);
 270                 return;
 271               }
 272           }
 273         else
 274           {
 275             const size_type __tmp_capacity = __rcs._M_allocated_capacity;
 276             traits_type::copy(__rcs._M_local_data, _M_local_data,
 277                               _S_local_capacity + 1);
 278             _M_data(__rcs._M_data());
 279             __rcs._M_data(__rcs._M_local_data);
 280             _M_capacity(__tmp_capacity);
 281           }
 282       else
 283         {
 284           const size_type __tmp_capacity = _M_allocated_capacity;
 285           if (__rcs._M_is_local())
 286             {
 287               traits_type::copy(_M_local_data, __rcs._M_local_data,
 288                                 _S_local_capacity + 1);
 289               __rcs._M_data(_M_data());
 290               _M_data(_M_local_data);
 291             }
 292           else
 293             {
 294               _CharT* __tmp_ptr = _M_data();
 295               _M_data(__rcs._M_data());
 296               __rcs._M_data(__tmp_ptr);
 297               _M_capacity(__rcs._M_allocated_capacity);
 298             }
 299           __rcs._M_capacity(__tmp_capacity);
 300         }
 301
 302       const size_type __tmp_length = _M_length();
 303       _M_length(__rcs._M_length());
 304       __rcs._M_length(__tmp_length);
 305     }
 306
 307   template<typename _CharT, typename _Traits, typename _Alloc>
 308     _CharT*
 309     __sso_string_base<_CharT, _Traits, _Alloc>::
 310     _M_create(size_type& __capacity, size_type __old_capacity)
 311     {
 312       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 313       // 83.  String::npos vs. string::max_size()
 314       if (__capacity > _M_max_size())
 315         std::__throw_length_error(__N("__sso_string_base::_M_create"));
 316
 317       // The below implements an exponential growth policy, necessary to
 318       // meet amortized linear time requirements of the library: see
 319       // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
 320       if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
 321         {
 322           __capacity = 2 * __old_capacity;
 323           // Never allocate a string bigger than max_size.
 324           if (__capacity > _M_max_size())
 325             __capacity = _M_max_size();
 326         }
 327
 328       // NB: Need an array of char_type[__capacity], plus a terminating
 329       // null char_type() element.
 330       return _M_get_allocator().allocate(__capacity + 1);
 331     }
 332
 333   template<typename _CharT, typename _Traits, typename _Alloc>
 334     __sso_string_base<_CharT, _Traits, _Alloc>::
 335     __sso_string_base(const _Alloc& __a)
 336     : _M_dataplus(__a, _M_local_data)
 337     { _M_set_length(0); }
 338
 339   template<typename _CharT, typename _Traits, typename _Alloc>
 340     __sso_string_base<_CharT, _Traits, _Alloc>::
 341     __sso_string_base(const __sso_string_base& __rcs)
 342     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
 343     { _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
 344
 345 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 346   template<typename _CharT, typename _Traits, typename _Alloc>
 347     __sso_string_base<_CharT, _Traits, _Alloc>::
 348     __sso_string_base(__sso_string_base&& __rcs)
 349     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
 350     {
 351       if (__rcs._M_is_local())
 352         {
 353           if (__rcs._M_length())
 354             traits_type::copy(_M_local_data, __rcs._M_local_data,
 355                               _S_local_capacity + 1);
 356         }
 357       else
 358         {
 359           _M_data(__rcs._M_data());
 360           _M_capacity(__rcs._M_allocated_capacity);
 361         }
 362
 363       _M_length(__rcs._M_length());
 364       __rcs._M_length(0);
 365       __rcs._M_data(__rcs._M_local_data);
 366     }
 367 #endif
 368
 369   template<typename _CharT, typename _Traits, typename _Alloc>
 370     __sso_string_base<_CharT, _Traits, _Alloc>::
 371     __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
 372     : _M_dataplus(__a, _M_local_data)
 373     { _M_construct(__n, __c); }
 374
 375   template<typename _CharT, typename _Traits, typename _Alloc>
 376     template<typename _InputIterator>
 377     __sso_string_base<_CharT, _Traits, _Alloc>::
 378     __sso_string_base(_InputIterator __beg, _InputIterator __end,
 379                       const _Alloc& __a)
 380     : _M_dataplus(__a, _M_local_data)
 381     { _M_construct(__beg, __end); }
 382
 383   // NB: This is the special case for Input Iterators, used in
 384   // istreambuf_iterators, etc.
 385   // Input Iterators have a cost structure very different from
 386   // pointers, calling for a different coding style.
 387   template<typename _CharT, typename _Traits, typename _Alloc>
 388     template<typename _InIterator>
 389       void
 390       __sso_string_base<_CharT, _Traits, _Alloc>::
 391       _M_construct(_InIterator __beg, _InIterator __end,
 392                    std::input_iterator_tag)
 393       {
 394         size_type __len = 0;
 395         size_type __capacity = size_type(_S_local_capacity);
 396
 397         while (__beg != __end && __len < __capacity)
 398           {
 399             _M_data()[__len++] = *__beg;
 400             ++__beg;
 401           }
 402
 403         __try
 404           {
 405             while (__beg != __end)
 406               {
 407                 if (__len == __capacity)
 408                   {
 409                     // Allocate more space.
 410                     __capacity = __len + 1;
 411                     _CharT* __another = _M_create(__capacity, __len);
 412                     _S_copy(__another, _M_data(), __len);
 413                     _M_dispose();
 414                     _M_data(__another);
 415                     _M_capacity(__capacity);
 416                   }
 417                 _M_data()[__len++] = *__beg;
 418                 ++__beg;
 419               }
 420           }
 421         __catch(...)
 422           {
 423             _M_dispose();
 424             __throw_exception_again;
 425           }
 426
 427         _M_set_length(__len);
 428       }
 429
 430   template<typename _CharT, typename _Traits, typename _Alloc>
 431     template<typename _InIterator>
 432       void
 433       __sso_string_base<_CharT, _Traits, _Alloc>::
 434       _M_construct(_InIterator __beg, _InIterator __end,
 435                    std::forward_iterator_tag)
 436       {
 437         // NB: Not required, but considered best practice.
 438         if (__is_null_pointer(__beg) && __beg != __end)
 439           std::__throw_logic_error(__N("__sso_string_base::"
 440                                        "_M_construct null not valid"));
 441
 442         size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
 443
 444         if (__dnew > size_type(_S_local_capacity))
 445           {
 446             _M_data(_M_create(__dnew, size_type(0)));
 447             _M_capacity(__dnew);
 448           }
 449
 450         // Check for out_of_range and length_error exceptions.
 451         __try
 452           { _S_copy_chars(_M_data(), __beg, __end); }
 453         __catch(...)
 454           {
 455             _M_dispose();
 456             __throw_exception_again;
 457           }
 458
 459         _M_set_length(__dnew);
 460       }
 461
 462   template<typename _CharT, typename _Traits, typename _Alloc>
 463     void
 464     __sso_string_base<_CharT, _Traits, _Alloc>::
 465     _M_construct(size_type __n, _CharT __c)
 466     {
 467       if (__n > size_type(_S_local_capacity))
 468         {
 469           _M_data(_M_create(__n, size_type(0)));
 470           _M_capacity(__n);
 471         }
 472
 473       if (__n)
 474         _S_assign(_M_data(), __n, __c);
 475
 476       _M_set_length(__n);
 477     }
 478
 479   template<typename _CharT, typename _Traits, typename _Alloc>
 480     void
 481     __sso_string_base<_CharT, _Traits, _Alloc>::
 482     _M_assign(const __sso_string_base& __rcs)
 483     {
 484       if (this != &__rcs)
 485         {
 486           const size_type __rsize = __rcs._M_length();
 487           const size_type __capacity = _M_capacity();
 488
 489           if (__rsize > __capacity)
 490             {
 491               size_type __new_capacity = __rsize;
 492               _CharT* __tmp = _M_create(__new_capacity, __capacity);
 493               _M_dispose();
 494               _M_data(__tmp);
 495               _M_capacity(__new_capacity);
 496             }
 497
 498           if (__rsize)
 499             _S_copy(_M_data(), __rcs._M_data(), __rsize);
 500
 501           _M_set_length(__rsize);
 502         }
 503     }
 504
 505   template<typename _CharT, typename _Traits, typename _Alloc>
 506     void
 507     __sso_string_base<_CharT, _Traits, _Alloc>::
 508     _M_reserve(size_type __res)
 509     {
 510       // Make sure we don't shrink below the current size.
 511       if (__res < _M_length())
 512         __res = _M_length();
 513
 514       const size_type __capacity = _M_capacity();
 515       if (__res != __capacity)
 516         {
 517           if (__res > __capacity
 518               || __res > size_type(_S_local_capacity))
 519             {
 520               _CharT* __tmp = _M_create(__res, __capacity);
 521               _S_copy(__tmp, _M_data(), _M_length() + 1);
 522               _M_dispose();
 523               _M_data(__tmp);
 524               _M_capacity(__res);
 525             }
 526           else if (!_M_is_local())
 527             {
 528               _S_copy(_M_local_data, _M_data(), _M_length() + 1);
 529               _M_destroy(__capacity);
 530               _M_data(_M_local_data);
 531             }
 532         }
 533     }
 534
 535   template<typename _CharT, typename _Traits, typename _Alloc>
 536     void
 537     __sso_string_base<_CharT, _Traits, _Alloc>::
 538     _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 539               size_type __len2)
 540     {
 541       const size_type __how_much = _M_length() - __pos - __len1;
 542
 543       size_type __new_capacity = _M_length() + __len2 - __len1;
 544       _CharT* __r = _M_create(__new_capacity, _M_capacity());
 545
 546       if (__pos)
 547         _S_copy(__r, _M_data(), __pos);
 548       if (__s && __len2)
 549         _S_copy(__r + __pos, __s, __len2);
 550       if (__how_much)
 551         _S_copy(__r + __pos + __len2,
 552                 _M_data() + __pos + __len1, __how_much);
 553
 554       _M_dispose();
 555       _M_data(__r);
 556       _M_capacity(__new_capacity);
 557     }
 558
 559   template<typename _CharT, typename _Traits, typename _Alloc>
 560     void
 561     __sso_string_base<_CharT, _Traits, _Alloc>::
 562     _M_erase(size_type __pos, size_type __n)
 563     {
 564       const size_type __how_much = _M_length() - __pos - __n;
 565
 566       if (__how_much && __n)
 567         _S_move(_M_data() + __pos, _M_data() + __pos + __n,
 568                 __how_much);
 569
 570       _M_set_length(_M_length() - __n);
 571     }
 572
 573 _GLIBCXX_END_NAMESPACE
 574
 575 #endif /* _SSO_STRING_BASE_H */