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

   1 // Short-string-optimized versatile string base -*- C++ -*-
   2
   3 // Copyright (C) 2005, 2006 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 2, 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 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 /** @file ext/sso_string_base.h
  31  *  This file is a GNU extension to the Standard C++ Library.
  32  *  This is an internal header file, included by other library headers.
  33  *  You should not attempt to use it directly.
  34  */
  35
  36 #ifndef _SSO_STRING_BASE_H
  37 #define _SSO_STRING_BASE_H 1
  38
  39 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
  40
  41   template<typename _CharT, typename _Traits, typename _Alloc>
  42     class __sso_string_base
  43     : protected __vstring_utility<_CharT, _Traits, _Alloc>
  44     {
  45     public:
  46       typedef _Traits                                       traits_type;
  47       typedef typename _Traits::char_type                   value_type;
  48
  49       typedef __vstring_utility<_CharT, _Traits, _Alloc>    _Util_Base;
  50       typedef typename _Util_Base::_CharT_alloc_type        _CharT_alloc_type;
  51       typedef typename _CharT_alloc_type::size_type         size_type;
  52
  53     private:
  54       // The maximum number of individual char_type elements of an
  55       // individual string is determined by _S_max_size. This is the
  56       // value that will be returned by max_size().  (Whereas npos
  57       // is the maximum number of bytes the allocator can allocate.)
  58       // If one was to divvy up the theoretical largest size string,
  59       // with a terminating character and m _CharT elements, it'd
  60       // look like this:
  61       // npos = m * sizeof(_CharT) + sizeof(_CharT)
  62       // Solving for m:
  63       // m = npos / sizeof(_CharT) - 1
  64       // In addition, this implementation halfs this amount.
  65       enum { _S_max_size = (((static_cast<size_type>(-1)
  66                               / sizeof(_CharT)) - 1) / 2) };
  67
  68       // Data Members (private):
  69       typename _Util_Base::template _Alloc_hider<_CharT_alloc_type>
  70                                                             _M_dataplus;
  71       size_type                                             _M_string_length;
  72
  73       enum { _S_local_capacity = 15 };
  74
  75       union
  76       {
  77         _CharT           _M_local_data[_S_local_capacity + 1];
  78         size_type        _M_allocated_capacity;
  79       };
  80
  81       void
  82       _M_data(_CharT* __p)
  83       { _M_dataplus._M_p = __p; }
  84
  85       void
  86       _M_length(size_type __length)
  87       { _M_string_length = __length; }
  88
  89       void
  90       _M_capacity(size_type __capacity)
  91       { _M_allocated_capacity = __capacity; }
  92
  93       bool
  94       _M_is_local() const
  95       { return _M_data() == _M_local_data; }
  96
  97       // Create & Destroy
  98       _CharT*
  99       _M_create(size_type&, size_type);
 100
 101       void
 102       _M_dispose()
 103       {
 104         if (!_M_is_local())
 105           _M_destroy(_M_allocated_capacity);
 106       }
 107
 108       void
 109       _M_destroy(size_type) throw();
 110
 111       // _M_construct_aux is used to implement the 21.3.1 para 15 which
 112       // requires special behaviour if _InIterator is an integral type
 113       template<typename _InIterator>
 114         void
 115         _M_construct_aux(_InIterator __beg, _InIterator __end, __false_type)
 116         {
 117           typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
 118           _M_construct(__beg, __end, _Tag());
 119         }
 120
 121       template<typename _InIterator>
 122         void
 123         _M_construct_aux(_InIterator __beg, _InIterator __end, __true_type)
 124         { _M_construct(static_cast<size_type>(__beg),
 125                        static_cast<value_type>(__end)); }
 126
 127       template<typename _InIterator>
 128         void
 129         _M_construct(_InIterator __beg, _InIterator __end)
 130         {
 131           typedef typename std::__is_integer<_InIterator>::__type _Integral;
 132           _M_construct_aux(__beg, __end, _Integral());
 133         }
 134
 135       // For Input Iterators, used in istreambuf_iterators, etc.
 136       template<typename _InIterator>
 137         void
 138         _M_construct(_InIterator __beg, _InIterator __end,
 139                      std::input_iterator_tag);
 140
 141       // For forward_iterators up to random_access_iterators, used for
 142       // string::iterator, _CharT*, etc.
 143       template<typename _FwdIterator>
 144         void
 145         _M_construct(_FwdIterator __beg, _FwdIterator __end,
 146                      std::forward_iterator_tag);
 147
 148       void
 149       _M_construct(size_type __req, _CharT __c);
 150
 151     public:
 152       size_type
 153       _M_max_size() const
 154       { return size_type(_S_max_size); }
 155
 156       _CharT*
 157       _M_data() const
 158       { return _M_dataplus._M_p; }
 159
 160       size_type
 161       _M_length() const
 162       { return _M_string_length; }
 163
 164       size_type
 165       _M_capacity() const
 166       {
 167         return _M_is_local() ? size_type(_S_local_capacity)
 168                              : _M_allocated_capacity;
 169       }
 170
 171       bool
 172       _M_is_shared() const
 173       { return false; }
 174
 175       void
 176       _M_set_leaked() { }
 177
 178       void
 179       _M_leak() { }
 180
 181       void
 182       _M_set_length(size_type __n)
 183       {
 184         _M_length(__n);
 185         traits_type::assign(_M_data()[__n], _CharT());
 186       }
 187
 188       __sso_string_base()
 189       : _M_dataplus(_Alloc(), _M_local_data)
 190       { _M_set_length(0); }
 191
 192       __sso_string_base(const _Alloc& __a);
 193
 194       __sso_string_base(const __sso_string_base& __rcs);
 195
 196       __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a);
 197
 198       template<typename _InputIterator>
 199         __sso_string_base(_InputIterator __beg, _InputIterator __end,
 200                           const _Alloc& __a);
 201
 202       ~__sso_string_base()
 203       { _M_dispose(); }
 204
 205       _CharT_alloc_type&
 206       _M_get_allocator()
 207       { return _M_dataplus; }
 208
 209       const _CharT_alloc_type&
 210       _M_get_allocator() const
 211       { return _M_dataplus; }
 212
 213       void
 214       _M_swap(__sso_string_base& __rcs);
 215
 216       void
 217       _M_assign(const __sso_string_base& __rcs);
 218
 219       void
 220       _M_reserve(size_type __res);
 221
 222       void
 223       _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 224                 size_type __len2);
 225
 226       void
 227       _M_erase(size_type __pos, size_type __n);
 228
 229       bool
 230       _M_compare(const __sso_string_base&) const
 231       { return false; }
 232     };
 233
 234   template<typename _CharT, typename _Traits, typename _Alloc>
 235     void
 236     __sso_string_base<_CharT, _Traits, _Alloc>::
 237     _M_destroy(size_type __size) throw()
 238     { _M_dataplus._CharT_alloc_type::deallocate(_M_data(), __size + 1); }
 239
 240   template<typename _CharT, typename _Traits, typename _Alloc>
 241     void
 242     __sso_string_base<_CharT, _Traits, _Alloc>::
 243     _M_swap(__sso_string_base& __rcs)
 244     {
 245       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 246       // 431. Swapping containers with unequal allocators.
 247       std::__alloc_swap<_CharT_alloc_type>::_S_do_it(_M_get_allocator(),
 248                                                      __rcs._M_get_allocator());
 249
 250       if (_M_is_local())
 251         if (__rcs._M_is_local())
 252           {
 253             if (_M_length() && __rcs._M_length())
 254               {
 255                 _CharT __tmp_data[_S_local_capacity + 1];
 256                 traits_type::copy(__tmp_data, __rcs._M_local_data,
 257                                   _S_local_capacity + 1);
 258                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 259                                   _S_local_capacity + 1);
 260                 traits_type::copy(_M_local_data, __tmp_data,
 261                                   _S_local_capacity + 1);
 262               }
 263             else if (__rcs._M_length())
 264               {
 265                 traits_type::copy(_M_local_data, __rcs._M_local_data,
 266                                   _S_local_capacity + 1);
 267                 _M_length(__rcs._M_length());
 268                 __rcs._M_set_length(0);
 269                 return;
 270               }
 271             else if (_M_length())
 272               {
 273                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 274                                   _S_local_capacity + 1);
 275                 __rcs._M_length(_M_length());
 276                 _M_set_length(0);
 277                 return;
 278               }
 279           }
 280         else
 281           {
 282             const size_type __tmp_capacity = __rcs._M_allocated_capacity;
 283             traits_type::copy(__rcs._M_local_data, _M_local_data,
 284                               _S_local_capacity + 1);
 285             _M_data(__rcs._M_data());
 286             __rcs._M_data(__rcs._M_local_data);
 287             _M_capacity(__tmp_capacity);
 288           }
 289       else
 290         {
 291           const size_type __tmp_capacity = _M_allocated_capacity;
 292           if (__rcs._M_is_local())
 293             {
 294               traits_type::copy(_M_local_data, __rcs._M_local_data,
 295                                 _S_local_capacity + 1);
 296               __rcs._M_data(_M_data());
 297               _M_data(_M_local_data);
 298             }
 299           else
 300             {
 301               _CharT* __tmp_ptr = _M_data();
 302               _M_data(__rcs._M_data());
 303               __rcs._M_data(__tmp_ptr);
 304               _M_capacity(__rcs._M_allocated_capacity);
 305             }
 306           __rcs._M_capacity(__tmp_capacity);
 307         }
 308
 309       const size_type __tmp_length = _M_length();
 310       _M_length(__rcs._M_length());
 311       __rcs._M_length(__tmp_length);
 312     }
 313
 314   template<typename _CharT, typename _Traits, typename _Alloc>
 315     _CharT*
 316     __sso_string_base<_CharT, _Traits, _Alloc>::
 317     _M_create(size_type& __capacity, size_type __old_capacity)
 318     {
 319       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 320       // 83.  String::npos vs. string::max_size()
 321       if (__capacity > size_type(_S_max_size))
 322         std::__throw_length_error(__N("__sso_string_base::_M_create"));
 323
 324       // The below implements an exponential growth policy, necessary to
 325       // meet amortized linear time requirements of the library: see
 326       // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
 327       if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
 328         {
 329           __capacity = 2 * __old_capacity;
 330           // Never allocate a string bigger than _S_max_size.
 331           if (__capacity > size_type(_S_max_size))
 332             __capacity = size_type(_S_max_size);
 333         }
 334
 335       // NB: Need an array of char_type[__capacity], plus a terminating
 336       // null char_type() element.
 337       return _M_dataplus._CharT_alloc_type::allocate(__capacity + 1);
 338     }
 339
 340   template<typename _CharT, typename _Traits, typename _Alloc>
 341     __sso_string_base<_CharT, _Traits, _Alloc>::
 342     __sso_string_base(const _Alloc& __a)
 343     : _M_dataplus(__a, _M_local_data)
 344     { _M_set_length(0); }
 345
 346   template<typename _CharT, typename _Traits, typename _Alloc>
 347     __sso_string_base<_CharT, _Traits, _Alloc>::
 348     __sso_string_base(const __sso_string_base& __rcs)
 349     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
 350     { _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
 351
 352   template<typename _CharT, typename _Traits, typename _Alloc>
 353     __sso_string_base<_CharT, _Traits, _Alloc>::
 354     __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
 355     : _M_dataplus(__a, _M_local_data)
 356     { _M_construct(__n, __c); }
 357
 358   template<typename _CharT, typename _Traits, typename _Alloc>
 359     template<typename _InputIterator>
 360     __sso_string_base<_CharT, _Traits, _Alloc>::
 361     __sso_string_base(_InputIterator __beg, _InputIterator __end,
 362                       const _Alloc& __a)
 363     : _M_dataplus(__a, _M_local_data)
 364     { _M_construct(__beg, __end); }
 365
 366   // NB: This is the special case for Input Iterators, used in
 367   // istreambuf_iterators, etc.
 368   // Input Iterators have a cost structure very different from
 369   // pointers, calling for a different coding style.
 370   template<typename _CharT, typename _Traits, typename _Alloc>
 371     template<typename _InIterator>
 372       void
 373       __sso_string_base<_CharT, _Traits, _Alloc>::
 374       _M_construct(_InIterator __beg, _InIterator __end,
 375                    std::input_iterator_tag)
 376       {
 377         size_type __len = 0;
 378         size_type __capacity = size_type(_S_local_capacity);
 379
 380         while (__beg != __end && __len < __capacity)
 381           {
 382             _M_data()[__len++] = *__beg;
 383             ++__beg;
 384           }
 385
 386         try
 387           {
 388             while (__beg != __end)
 389               {
 390                 if (__len == __capacity)
 391                   {
 392                     // Allocate more space.
 393                     __capacity = __len + 1;
 394                     _CharT* __another = _M_create(__capacity, __len);
 395                     _S_copy(__another, _M_data(), __len);
 396                     _M_dispose();
 397                     _M_data(__another);
 398                     _M_capacity(__capacity);
 399                   }
 400                 _M_data()[__len++] = *__beg;
 401                 ++__beg;
 402               }
 403           }
 404         catch(...)
 405           {
 406             _M_dispose();
 407             __throw_exception_again;
 408           }
 409
 410         _M_set_length(__len);
 411       }
 412
 413   template<typename _CharT, typename _Traits, typename _Alloc>
 414     template<typename _InIterator>
 415       void
 416       __sso_string_base<_CharT, _Traits, _Alloc>::
 417       _M_construct(_InIterator __beg, _InIterator __end,
 418                    std::forward_iterator_tag)
 419       {
 420         // NB: Not required, but considered best practice.
 421         if (__builtin_expect(_S_is_null_pointer(__beg) && __beg != __end, 0))
 422           std::__throw_logic_error(__N("__sso_string_base::"
 423                                        "_M_construct NULL not valid"));
 424
 425         size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
 426
 427         if (__dnew > size_type(_S_local_capacity))
 428           {
 429             _M_data(_M_create(__dnew, size_type(0)));
 430             _M_capacity(__dnew);
 431           }
 432
 433         // Check for out_of_range and length_error exceptions.
 434         try
 435           { _S_copy_chars(_M_data(), __beg, __end); }
 436         catch(...)
 437           {
 438             _M_dispose();
 439             __throw_exception_again;
 440           }
 441
 442         _M_set_length(__dnew);
 443       }
 444
 445   template<typename _CharT, typename _Traits, typename _Alloc>
 446     void
 447     __sso_string_base<_CharT, _Traits, _Alloc>::
 448     _M_construct(size_type __n, _CharT __c)
 449     {
 450       if (__n > size_type(_S_local_capacity))
 451         {
 452           _M_data(_M_create(__n, size_type(0)));
 453           _M_capacity(__n);
 454         }
 455
 456       if (__n)
 457         _S_assign(_M_data(), __n, __c);
 458
 459       _M_set_length(__n);
 460     }
 461
 462   template<typename _CharT, typename _Traits, typename _Alloc>
 463     void
 464     __sso_string_base<_CharT, _Traits, _Alloc>::
 465     _M_assign(const __sso_string_base& __rcs)
 466     {
 467       if (this != &__rcs)
 468         {
 469           const size_type __rsize = __rcs._M_length();
 470           const size_type __capacity = _M_capacity();
 471
 472           if (__rsize > __capacity)
 473             {
 474               size_type __new_capacity = __rsize;
 475               _CharT* __tmp = _M_create(__new_capacity, __capacity);
 476               _M_dispose();
 477               _M_data(__tmp);
 478               _M_capacity(__new_capacity);
 479             }
 480
 481           if (__rsize)
 482             _S_copy(_M_data(), __rcs._M_data(), __rsize);
 483
 484           _M_set_length(__rsize);
 485         }
 486     }
 487
 488   template<typename _CharT, typename _Traits, typename _Alloc>
 489     void
 490     __sso_string_base<_CharT, _Traits, _Alloc>::
 491     _M_reserve(size_type __res)
 492     {
 493       // Make sure we don't shrink below the current size.
 494       if (__res < _M_length())
 495         __res = _M_length();
 496
 497       const size_type __capacity = _M_capacity();
 498       if (__res != __capacity)
 499         {
 500           if (__res > __capacity
 501               || __res > size_type(_S_local_capacity))
 502             {
 503               _CharT* __tmp = _M_create(__res, __capacity);
 504               _S_copy(__tmp, _M_data(), _M_length() + 1);
 505               _M_dispose();
 506               _M_data(__tmp);
 507               _M_capacity(__res);
 508             }
 509           else if (!_M_is_local())
 510             {
 511               _S_copy(_M_local_data, _M_data(), _M_length() + 1);
 512               _M_destroy(__capacity);
 513               _M_data(_M_local_data);
 514             }
 515         }
 516     }
 517
 518   template<typename _CharT, typename _Traits, typename _Alloc>
 519     void
 520     __sso_string_base<_CharT, _Traits, _Alloc>::
 521     _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 522               const size_type __len2)
 523     {
 524       const size_type __how_much = _M_length() - __pos - __len1;
 525
 526       size_type __new_capacity = _M_length() + __len2 - __len1;
 527       _CharT* __r = _M_create(__new_capacity, _M_capacity());
 528
 529       if (__pos)
 530         _S_copy(__r, _M_data(), __pos);
 531       if (__s && __len2)
 532         _S_copy(__r + __pos, __s, __len2);
 533       if (__how_much)
 534         _S_copy(__r + __pos + __len2,
 535                 _M_data() + __pos + __len1, __how_much);
 536
 537       _M_dispose();
 538       _M_data(__r);
 539       _M_capacity(__new_capacity);
 540     }
 541
 542   template<typename _CharT, typename _Traits, typename _Alloc>
 543     void
 544     __sso_string_base<_CharT, _Traits, _Alloc>::
 545     _M_erase(size_type __pos, size_type __n)
 546     {
 547       const size_type __how_much = _M_length() - __pos - __n;
 548
 549       if (__how_much && __n)
 550         _S_move(_M_data() + __pos, _M_data() + __pos + __n,
 551                 __how_much);
 552
 553       _M_set_length(_M_length() - __n);
 554     }
 555
 556   template<>
 557     inline bool
 558     __sso_string_base<char, std::char_traits<char>,
 559                       std::allocator<char> >::
 560     _M_compare(const __sso_string_base& __rcs) const
 561     {
 562       if (this == &__rcs)
 563         return true;
 564       return false;
 565     }
 566
 567   template<>
 568     inline bool
 569     __sso_string_base<wchar_t, std::char_traits<wchar_t>,
 570                       std::allocator<wchar_t> >::
 571     _M_compare(const __sso_string_base& __rcs) const
 572     {
 573       if (this == &__rcs)
 574         return true;
 575       return false;
 576     }
 577
 578 _GLIBCXX_END_NAMESPACE
 579
 580 #endif /* _SSO_STRING_BASE_H */