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 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
  35 {
  36 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  37
  38   template<typename _CharT, typename _Traits, typename _Alloc>
  39     class __sso_string_base
  40     : protected __vstring_utility<_CharT, _Traits, _Alloc>
  41     {
  42     public:
  43       typedef _Traits                                       traits_type;
  44       typedef typename _Traits::char_type                   value_type;
  45
  46       typedef __vstring_utility<_CharT, _Traits, _Alloc>    _Util_Base;
  47       typedef typename _Util_Base::_CharT_alloc_type        _CharT_alloc_type;
  48       typedef typename _CharT_alloc_type::size_type         size_type;
  49
  50     private:
  51       // Data Members:
  52       typename _Util_Base::template _Alloc_hider<_CharT_alloc_type>
  53                                                             _M_dataplus;
  54       size_type                                             _M_string_length;
  55
  56       enum { _S_local_capacity = 15 };
  57
  58       union
  59       {
  60         _CharT           _M_local_data[_S_local_capacity + 1];
  61         size_type        _M_allocated_capacity;
  62       };
  63
  64       void
  65       _M_data(_CharT* __p)
  66       { _M_dataplus._M_p = __p; }
  67
  68       void
  69       _M_length(size_type __length)
  70       { _M_string_length = __length; }
  71
  72       void
  73       _M_capacity(size_type __capacity)
  74       { _M_allocated_capacity = __capacity; }
  75
  76       bool
  77       _M_is_local() const
  78       { return _M_data() == _M_local_data; }
  79
  80       // Create & Destroy
  81       _CharT*
  82       _M_create(size_type&, size_type);
  83
  84       void
  85       _M_dispose()
  86       {
  87         if (!_M_is_local())
  88           _M_destroy(_M_allocated_capacity);
  89       }
  90
  91       void
  92       _M_destroy(size_type __size) throw()
  93       { _M_get_allocator().deallocate(_M_data(), __size + 1); }
  94
  95       // _M_construct_aux is used to implement the 21.3.1 para 15 which
  96       // requires special behaviour if _InIterator is an integral type
  97       template<typename _InIterator>
  98         void
  99         _M_construct_aux(_InIterator __beg, _InIterator __end,
 100                          std::__false_type)
 101         {
 102           typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
 103           _M_construct(__beg, __end, _Tag());
 104         }
 105
 106       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 107       // 438. Ambiguity in the "do the right thing" clause
 108       template<typename _Integer>
 109         void
 110         _M_construct_aux(_Integer __beg, _Integer __end, std::__true_type)
 111         { _M_construct_aux_2(static_cast<size_type>(__beg), __end); }
 112
 113       void
 114       _M_construct_aux_2(size_type __req, _CharT __c)
 115       { _M_construct(__req, __c); }
 116
 117       template<typename _InIterator>
 118         void
 119         _M_construct(_InIterator __beg, _InIterator __end)
 120         {
 121           typedef typename std::__is_integer<_InIterator>::__type _Integral;
 122           _M_construct_aux(__beg, __end, _Integral());
 123         }
 124
 125       // For Input Iterators, used in istreambuf_iterators, etc.
 126       template<typename _InIterator>
 127         void
 128         _M_construct(_InIterator __beg, _InIterator __end,
 129                      std::input_iterator_tag);
 130
 131       // For forward_iterators up to random_access_iterators, used for
 132       // string::iterator, _CharT*, etc.
 133       template<typename _FwdIterator>
 134         void
 135         _M_construct(_FwdIterator __beg, _FwdIterator __end,
 136                      std::forward_iterator_tag);
 137
 138       void
 139       _M_construct(size_type __req, _CharT __c);
 140
 141     public:
 142       size_type
 143       _M_max_size() const
 144       { return (_M_get_allocator().max_size() - 1) / 2; }
 145
 146       _CharT*
 147       _M_data() const
 148       { return _M_dataplus._M_p; }
 149
 150       size_type
 151       _M_length() const
 152       { return _M_string_length; }
 153
 154       size_type
 155       _M_capacity() const
 156       {
 157         return _M_is_local() ? size_type(_S_local_capacity)
 158                              : _M_allocated_capacity;
 159       }
 160
 161       bool
 162       _M_is_shared() const
 163       { return false; }
 164
 165       void
 166       _M_set_leaked() { }
 167
 168       void
 169       _M_leak() { }
 170
 171       void
 172       _M_set_length(size_type __n)
 173       {
 174         _M_length(__n);
 175         traits_type::assign(_M_data()[__n], _CharT());
 176       }
 177
 178       __sso_string_base()
 179       : _M_dataplus(_M_local_data)
 180       { _M_set_length(0); }
 181
 182       __sso_string_base(const _Alloc& __a);
 183
 184       __sso_string_base(const __sso_string_base& __rcs);
 185
 186 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 187       __sso_string_base(__sso_string_base&& __rcs);
 188 #endif
 189
 190       __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a);
 191
 192       template<typename _InputIterator>
 193         __sso_string_base(_InputIterator __beg, _InputIterator __end,
 194                           const _Alloc& __a);
 195
 196       ~__sso_string_base()
 197       { _M_dispose(); }
 198
 199       _CharT_alloc_type&
 200       _M_get_allocator()
 201       { return _M_dataplus; }
 202
 203       const _CharT_alloc_type&
 204       _M_get_allocator() const
 205       { return _M_dataplus; }
 206
 207       void
 208       _M_swap(__sso_string_base& __rcs);
 209
 210       void
 211       _M_assign(const __sso_string_base& __rcs);
 212
 213       void
 214       _M_reserve(size_type __res);
 215
 216       void
 217       _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 218                 size_type __len2);
 219
 220       void
 221       _M_erase(size_type __pos, size_type __n);
 222
 223       void
 224       _M_clear()
 225       { _M_set_length(0); }
 226
 227       bool
 228       _M_compare(const __sso_string_base&) const
 229       { return false; }
 230     };
 231
 232   template<typename _CharT, typename _Traits, typename _Alloc>
 233     void
 234     __sso_string_base<_CharT, _Traits, _Alloc>::
 235     _M_swap(__sso_string_base& __rcs)
 236     {
 237       if (this == &__rcs)
 238         return;
 239
 240       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 241       // 431. Swapping containers with unequal allocators.
 242       std::__alloc_swap<_CharT_alloc_type>::_S_do_it(_M_get_allocator(),
 243                                                      __rcs._M_get_allocator());
 244
 245       if (_M_is_local())
 246         if (__rcs._M_is_local())
 247           {
 248             if (_M_length() && __rcs._M_length())
 249               {
 250                 _CharT __tmp_data[_S_local_capacity + 1];
 251                 traits_type::copy(__tmp_data, __rcs._M_local_data,
 252                                   _S_local_capacity + 1);
 253                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 254                                   _S_local_capacity + 1);
 255                 traits_type::copy(_M_local_data, __tmp_data,
 256                                   _S_local_capacity + 1);
 257               }
 258             else if (__rcs._M_length())
 259               {
 260                 traits_type::copy(_M_local_data, __rcs._M_local_data,
 261                                   _S_local_capacity + 1);
 262                 _M_length(__rcs._M_length());
 263                 __rcs._M_set_length(0);
 264                 return;
 265               }
 266             else if (_M_length())
 267               {
 268                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 269                                   _S_local_capacity + 1);
 270                 __rcs._M_length(_M_length());
 271                 _M_set_length(0);
 272                 return;
 273               }
 274           }
 275         else
 276           {
 277             const size_type __tmp_capacity = __rcs._M_allocated_capacity;
 278             traits_type::copy(__rcs._M_local_data, _M_local_data,
 279                               _S_local_capacity + 1);
 280             _M_data(__rcs._M_data());
 281             __rcs._M_data(__rcs._M_local_data);
 282             _M_capacity(__tmp_capacity);
 283           }
 284       else
 285         {
 286           const size_type __tmp_capacity = _M_allocated_capacity;
 287           if (__rcs._M_is_local())
 288             {
 289               traits_type::copy(_M_local_data, __rcs._M_local_data,
 290                                 _S_local_capacity + 1);
 291               __rcs._M_data(_M_data());
 292               _M_data(_M_local_data);
 293             }
 294           else
 295             {
 296               _CharT* __tmp_ptr = _M_data();
 297               _M_data(__rcs._M_data());
 298               __rcs._M_data(__tmp_ptr);
 299               _M_capacity(__rcs._M_allocated_capacity);
 300             }
 301           __rcs._M_capacity(__tmp_capacity);
 302         }
 303
 304       const size_type __tmp_length = _M_length();
 305       _M_length(__rcs._M_length());
 306       __rcs._M_length(__tmp_length);
 307     }
 308
 309   template<typename _CharT, typename _Traits, typename _Alloc>
 310     _CharT*
 311     __sso_string_base<_CharT, _Traits, _Alloc>::
 312     _M_create(size_type& __capacity, size_type __old_capacity)
 313     {
 314       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 315       // 83.  String::npos vs. string::max_size()
 316       if (__capacity > _M_max_size())
 317         std::__throw_length_error(__N("__sso_string_base::_M_create"));
 318
 319       // The below implements an exponential growth policy, necessary to
 320       // meet amortized linear time requirements of the library: see
 321       // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
 322       if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
 323         {
 324           __capacity = 2 * __old_capacity;
 325           // Never allocate a string bigger than max_size.
 326           if (__capacity > _M_max_size())
 327             __capacity = _M_max_size();
 328         }
 329
 330       // NB: Need an array of char_type[__capacity], plus a terminating
 331       // null char_type() element.
 332       return _M_get_allocator().allocate(__capacity + 1);
 333     }
 334
 335   template<typename _CharT, typename _Traits, typename _Alloc>
 336     __sso_string_base<_CharT, _Traits, _Alloc>::
 337     __sso_string_base(const _Alloc& __a)
 338     : _M_dataplus(__a, _M_local_data)
 339     { _M_set_length(0); }
 340
 341   template<typename _CharT, typename _Traits, typename _Alloc>
 342     __sso_string_base<_CharT, _Traits, _Alloc>::
 343     __sso_string_base(const __sso_string_base& __rcs)
 344     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
 345     { _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
 346
 347 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 348   template<typename _CharT, typename _Traits, typename _Alloc>
 349     __sso_string_base<_CharT, _Traits, _Alloc>::
 350     __sso_string_base(__sso_string_base&& __rcs)
 351     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
 352     {
 353       if (__rcs._M_is_local())
 354         {
 355           if (__rcs._M_length())
 356             traits_type::copy(_M_local_data, __rcs._M_local_data,
 357                               _S_local_capacity + 1);
 358         }
 359       else
 360         {
 361           _M_data(__rcs._M_data());
 362           _M_capacity(__rcs._M_allocated_capacity);
 363         }
 364
 365       _M_length(__rcs._M_length());
 366       __rcs._M_length(0);
 367       __rcs._M_data(__rcs._M_local_data);
 368     }
 369 #endif
 370
 371   template<typename _CharT, typename _Traits, typename _Alloc>
 372     __sso_string_base<_CharT, _Traits, _Alloc>::
 373     __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
 374     : _M_dataplus(__a, _M_local_data)
 375     { _M_construct(__n, __c); }
 376
 377   template<typename _CharT, typename _Traits, typename _Alloc>
 378     template<typename _InputIterator>
 379     __sso_string_base<_CharT, _Traits, _Alloc>::
 380     __sso_string_base(_InputIterator __beg, _InputIterator __end,
 381                       const _Alloc& __a)
 382     : _M_dataplus(__a, _M_local_data)
 383     { _M_construct(__beg, __end); }
 384
 385   // NB: This is the special case for Input Iterators, used in
 386   // istreambuf_iterators, etc.
 387   // Input Iterators have a cost structure very different from
 388   // pointers, calling for a different coding style.
 389   template<typename _CharT, typename _Traits, typename _Alloc>
 390     template<typename _InIterator>
 391       void
 392       __sso_string_base<_CharT, _Traits, _Alloc>::
 393       _M_construct(_InIterator __beg, _InIterator __end,
 394                    std::input_iterator_tag)
 395       {
 396         size_type __len = 0;
 397         size_type __capacity = size_type(_S_local_capacity);
 398
 399         while (__beg != __end && __len < __capacity)
 400           {
 401             _M_data()[__len++] = *__beg;
 402             ++__beg;
 403           }
 404
 405         __try
 406           {
 407             while (__beg != __end)
 408               {
 409                 if (__len == __capacity)
 410                   {
 411                     // Allocate more space.
 412                     __capacity = __len + 1;
 413                     _CharT* __another = _M_create(__capacity, __len);
 414                     _S_copy(__another, _M_data(), __len);
 415                     _M_dispose();
 416                     _M_data(__another);
 417                     _M_capacity(__capacity);
 418                   }
 419                 _M_data()[__len++] = *__beg;
 420                 ++__beg;
 421               }
 422           }
 423         __catch(...)
 424           {
 425             _M_dispose();
 426             __throw_exception_again;
 427           }
 428
 429         _M_set_length(__len);
 430       }
 431
 432   template<typename _CharT, typename _Traits, typename _Alloc>
 433     template<typename _InIterator>
 434       void
 435       __sso_string_base<_CharT, _Traits, _Alloc>::
 436       _M_construct(_InIterator __beg, _InIterator __end,
 437                    std::forward_iterator_tag)
 438       {
 439         // NB: Not required, but considered best practice.
 440         if (__is_null_pointer(__beg) && __beg != __end)
 441           std::__throw_logic_error(__N("__sso_string_base::"
 442                                        "_M_construct null not valid"));
 443
 444         size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
 445
 446         if (__dnew > size_type(_S_local_capacity))
 447           {
 448             _M_data(_M_create(__dnew, size_type(0)));
 449             _M_capacity(__dnew);
 450           }
 451
 452         // Check for out_of_range and length_error exceptions.
 453         __try
 454           { _S_copy_chars(_M_data(), __beg, __end); }
 455         __catch(...)
 456           {
 457             _M_dispose();
 458             __throw_exception_again;
 459           }
 460
 461         _M_set_length(__dnew);
 462       }
 463
 464   template<typename _CharT, typename _Traits, typename _Alloc>
 465     void
 466     __sso_string_base<_CharT, _Traits, _Alloc>::
 467     _M_construct(size_type __n, _CharT __c)
 468     {
 469       if (__n > size_type(_S_local_capacity))
 470         {
 471           _M_data(_M_create(__n, size_type(0)));
 472           _M_capacity(__n);
 473         }
 474
 475       if (__n)
 476         _S_assign(_M_data(), __n, __c);
 477
 478       _M_set_length(__n);
 479     }
 480
 481   template<typename _CharT, typename _Traits, typename _Alloc>
 482     void
 483     __sso_string_base<_CharT, _Traits, _Alloc>::
 484     _M_assign(const __sso_string_base& __rcs)
 485     {
 486       if (this != &__rcs)
 487         {
 488           const size_type __rsize = __rcs._M_length();
 489           const size_type __capacity = _M_capacity();
 490
 491           if (__rsize > __capacity)
 492             {
 493               size_type __new_capacity = __rsize;
 494               _CharT* __tmp = _M_create(__new_capacity, __capacity);
 495               _M_dispose();
 496               _M_data(__tmp);
 497               _M_capacity(__new_capacity);
 498             }
 499
 500           if (__rsize)
 501             _S_copy(_M_data(), __rcs._M_data(), __rsize);
 502
 503           _M_set_length(__rsize);
 504         }
 505     }
 506
 507   template<typename _CharT, typename _Traits, typename _Alloc>
 508     void
 509     __sso_string_base<_CharT, _Traits, _Alloc>::
 510     _M_reserve(size_type __res)
 511     {
 512       // Make sure we don't shrink below the current size.
 513       if (__res < _M_length())
 514         __res = _M_length();
 515
 516       const size_type __capacity = _M_capacity();
 517       if (__res != __capacity)
 518         {
 519           if (__res > __capacity
 520               || __res > size_type(_S_local_capacity))
 521             {
 522               _CharT* __tmp = _M_create(__res, __capacity);
 523               _S_copy(__tmp, _M_data(), _M_length() + 1);
 524               _M_dispose();
 525               _M_data(__tmp);
 526               _M_capacity(__res);
 527             }
 528           else if (!_M_is_local())
 529             {
 530               _S_copy(_M_local_data, _M_data(), _M_length() + 1);
 531               _M_destroy(__capacity);
 532               _M_data(_M_local_data);
 533             }
 534         }
 535     }
 536
 537   template<typename _CharT, typename _Traits, typename _Alloc>
 538     void
 539     __sso_string_base<_CharT, _Traits, _Alloc>::
 540     _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 541               size_type __len2)
 542     {
 543       const size_type __how_much = _M_length() - __pos - __len1;
 544
 545       size_type __new_capacity = _M_length() + __len2 - __len1;
 546       _CharT* __r = _M_create(__new_capacity, _M_capacity());
 547
 548       if (__pos)
 549         _S_copy(__r, _M_data(), __pos);
 550       if (__s && __len2)
 551         _S_copy(__r + __pos, __s, __len2);
 552       if (__how_much)
 553         _S_copy(__r + __pos + __len2,
 554                 _M_data() + __pos + __len1, __how_much);
 555
 556       _M_dispose();
 557       _M_data(__r);
 558       _M_capacity(__new_capacity);
 559     }
 560
 561   template<typename _CharT, typename _Traits, typename _Alloc>
 562     void
 563     __sso_string_base<_CharT, _Traits, _Alloc>::
 564     _M_erase(size_type __pos, size_type __n)
 565     {
 566       const size_type __how_much = _M_length() - __pos - __n;
 567
 568       if (__how_much && __n)
 569         _S_move(_M_data() + __pos, _M_data() + __pos + __n,
 570                 __how_much);
 571
 572       _M_set_length(_M_length() - __n);
 573     }
 574
 575 _GLIBCXX_END_NAMESPACE_VERSION
 576 } // namespace
 577
 578 #endif /* _SSO_STRING_BASE_H */