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