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

   1 // Short-string-optimized versatile string base -*- C++ -*-
   2
   3 // Copyright (C) 2005, 2006, 2007 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       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 110       // 438. Ambiguity in the "do the right thing" clause
 111       template<typename _Integer>
 112         void
 113         _M_construct_aux(_Integer __beg, _Integer __end, std::__true_type)
 114         { _M_construct(static_cast<size_type>(__beg), __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(_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 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 186       __sso_string_base(__sso_string_base&& __rcs);
 187 #endif
 188
 189       __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a);
 190
 191       template<typename _InputIterator>
 192         __sso_string_base(_InputIterator __beg, _InputIterator __end,
 193                           const _Alloc& __a);
 194
 195       ~__sso_string_base()
 196       { _M_dispose(); }
 197
 198       _CharT_alloc_type&
 199       _M_get_allocator()
 200       { return _M_dataplus; }
 201
 202       const _CharT_alloc_type&
 203       _M_get_allocator() const
 204       { return _M_dataplus; }
 205
 206       void
 207       _M_swap(__sso_string_base& __rcs);
 208
 209       void
 210       _M_assign(const __sso_string_base& __rcs);
 211
 212       void
 213       _M_reserve(size_type __res);
 214
 215       void
 216       _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 217                 size_type __len2);
 218
 219       void
 220       _M_erase(size_type __pos, size_type __n);
 221
 222       void
 223       _M_clear()
 224       { _M_set_length(0); }
 225
 226       bool
 227       _M_compare(const __sso_string_base&) const
 228       { return false; }
 229     };
 230
 231   template<typename _CharT, typename _Traits, typename _Alloc>
 232     void
 233     __sso_string_base<_CharT, _Traits, _Alloc>::
 234     _M_swap(__sso_string_base& __rcs)
 235     {
 236       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 237       // 431. Swapping containers with unequal allocators.
 238       std::__alloc_swap<_CharT_alloc_type>::_S_do_it(_M_get_allocator(),
 239                                                      __rcs._M_get_allocator());
 240
 241       if (_M_is_local())
 242         if (__rcs._M_is_local())
 243           {
 244             if (_M_length() && __rcs._M_length())
 245               {
 246                 _CharT __tmp_data[_S_local_capacity + 1];
 247                 traits_type::copy(__tmp_data, __rcs._M_local_data,
 248                                   _S_local_capacity + 1);
 249                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 250                                   _S_local_capacity + 1);
 251                 traits_type::copy(_M_local_data, __tmp_data,
 252                                   _S_local_capacity + 1);
 253               }
 254             else if (__rcs._M_length())
 255               {
 256                 traits_type::copy(_M_local_data, __rcs._M_local_data,
 257                                   _S_local_capacity + 1);
 258                 _M_length(__rcs._M_length());
 259                 __rcs._M_set_length(0);
 260                 return;
 261               }
 262             else if (_M_length())
 263               {
 264                 traits_type::copy(__rcs._M_local_data, _M_local_data,
 265                                   _S_local_capacity + 1);
 266                 __rcs._M_length(_M_length());
 267                 _M_set_length(0);
 268                 return;
 269               }
 270           }
 271         else
 272           {
 273             const size_type __tmp_capacity = __rcs._M_allocated_capacity;
 274             traits_type::copy(__rcs._M_local_data, _M_local_data,
 275                               _S_local_capacity + 1);
 276             _M_data(__rcs._M_data());
 277             __rcs._M_data(__rcs._M_local_data);
 278             _M_capacity(__tmp_capacity);
 279           }
 280       else
 281         {
 282           const size_type __tmp_capacity = _M_allocated_capacity;
 283           if (__rcs._M_is_local())
 284             {
 285               traits_type::copy(_M_local_data, __rcs._M_local_data,
 286                                 _S_local_capacity + 1);
 287               __rcs._M_data(_M_data());
 288               _M_data(_M_local_data);
 289             }
 290           else
 291             {
 292               _CharT* __tmp_ptr = _M_data();
 293               _M_data(__rcs._M_data());
 294               __rcs._M_data(__tmp_ptr);
 295               _M_capacity(__rcs._M_allocated_capacity);
 296             }
 297           __rcs._M_capacity(__tmp_capacity);
 298         }
 299
 300       const size_type __tmp_length = _M_length();
 301       _M_length(__rcs._M_length());
 302       __rcs._M_length(__tmp_length);
 303     }
 304
 305   template<typename _CharT, typename _Traits, typename _Alloc>
 306     _CharT*
 307     __sso_string_base<_CharT, _Traits, _Alloc>::
 308     _M_create(size_type& __capacity, size_type __old_capacity)
 309     {
 310       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 311       // 83.  String::npos vs. string::max_size()
 312       if (__capacity > _M_max_size())
 313         std::__throw_length_error(__N("__sso_string_base::_M_create"));
 314
 315       // The below implements an exponential growth policy, necessary to
 316       // meet amortized linear time requirements of the library: see
 317       // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
 318       if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
 319         {
 320           __capacity = 2 * __old_capacity;
 321           // Never allocate a string bigger than max_size.
 322           if (__capacity > _M_max_size())
 323             __capacity = _M_max_size();
 324         }
 325
 326       // NB: Need an array of char_type[__capacity], plus a terminating
 327       // null char_type() element.
 328       return _M_get_allocator().allocate(__capacity + 1);
 329     }
 330
 331   template<typename _CharT, typename _Traits, typename _Alloc>
 332     __sso_string_base<_CharT, _Traits, _Alloc>::
 333     __sso_string_base(const _Alloc& __a)
 334     : _M_dataplus(__a, _M_local_data)
 335     { _M_set_length(0); }
 336
 337   template<typename _CharT, typename _Traits, typename _Alloc>
 338     __sso_string_base<_CharT, _Traits, _Alloc>::
 339     __sso_string_base(const __sso_string_base& __rcs)
 340     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
 341     { _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
 342
 343 #ifdef __GXX_EXPERIMENTAL_CXX0X__
 344   template<typename _CharT, typename _Traits, typename _Alloc>
 345     __sso_string_base<_CharT, _Traits, _Alloc>::
 346     __sso_string_base(__sso_string_base&& __rcs)
 347     : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
 348     {
 349       if (__rcs._M_is_local())
 350         {
 351           if (__rcs._M_length())
 352             traits_type::copy(_M_local_data, __rcs._M_local_data,
 353                               _S_local_capacity + 1);
 354         }
 355       else
 356         {
 357           _M_data(__rcs._M_data());
 358           _M_capacity(__rcs._M_allocated_capacity);
 359         }
 360
 361       _M_length(__rcs._M_length());
 362       __rcs._M_length(0);
 363       __rcs._M_data(__rcs._M_local_data);
 364     }
 365 #endif
 366
 367   template<typename _CharT, typename _Traits, typename _Alloc>
 368     __sso_string_base<_CharT, _Traits, _Alloc>::
 369     __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
 370     : _M_dataplus(__a, _M_local_data)
 371     { _M_construct(__n, __c); }
 372
 373   template<typename _CharT, typename _Traits, typename _Alloc>
 374     template<typename _InputIterator>
 375     __sso_string_base<_CharT, _Traits, _Alloc>::
 376     __sso_string_base(_InputIterator __beg, _InputIterator __end,
 377                       const _Alloc& __a)
 378     : _M_dataplus(__a, _M_local_data)
 379     { _M_construct(__beg, __end); }
 380
 381   // NB: This is the special case for Input Iterators, used in
 382   // istreambuf_iterators, etc.
 383   // Input Iterators have a cost structure very different from
 384   // pointers, calling for a different coding style.
 385   template<typename _CharT, typename _Traits, typename _Alloc>
 386     template<typename _InIterator>
 387       void
 388       __sso_string_base<_CharT, _Traits, _Alloc>::
 389       _M_construct(_InIterator __beg, _InIterator __end,
 390                    std::input_iterator_tag)
 391       {
 392         size_type __len = 0;
 393         size_type __capacity = size_type(_S_local_capacity);
 394
 395         while (__beg != __end && __len < __capacity)
 396           {
 397             _M_data()[__len++] = *__beg;
 398             ++__beg;
 399           }
 400
 401         try
 402           {
 403             while (__beg != __end)
 404               {
 405                 if (__len == __capacity)
 406                   {
 407                     // Allocate more space.
 408                     __capacity = __len + 1;
 409                     _CharT* __another = _M_create(__capacity, __len);
 410                     _S_copy(__another, _M_data(), __len);
 411                     _M_dispose();
 412                     _M_data(__another);
 413                     _M_capacity(__capacity);
 414                   }
 415                 _M_data()[__len++] = *__beg;
 416                 ++__beg;
 417               }
 418           }
 419         catch(...)
 420           {
 421             _M_dispose();
 422             __throw_exception_again;
 423           }
 424
 425         _M_set_length(__len);
 426       }
 427
 428   template<typename _CharT, typename _Traits, typename _Alloc>
 429     template<typename _InIterator>
 430       void
 431       __sso_string_base<_CharT, _Traits, _Alloc>::
 432       _M_construct(_InIterator __beg, _InIterator __end,
 433                    std::forward_iterator_tag)
 434       {
 435         // NB: Not required, but considered best practice.
 436         if (__builtin_expect(__is_null_pointer(__beg) && __beg != __end, 0))
 437           std::__throw_logic_error(__N("__sso_string_base::"
 438                                        "_M_construct NULL not valid"));
 439
 440         size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
 441
 442         if (__dnew > size_type(_S_local_capacity))
 443           {
 444             _M_data(_M_create(__dnew, size_type(0)));
 445             _M_capacity(__dnew);
 446           }
 447
 448         // Check for out_of_range and length_error exceptions.
 449         try
 450           { _S_copy_chars(_M_data(), __beg, __end); }
 451         catch(...)
 452           {
 453             _M_dispose();
 454             __throw_exception_again;
 455           }
 456
 457         _M_set_length(__dnew);
 458       }
 459
 460   template<typename _CharT, typename _Traits, typename _Alloc>
 461     void
 462     __sso_string_base<_CharT, _Traits, _Alloc>::
 463     _M_construct(size_type __n, _CharT __c)
 464     {
 465       if (__n > size_type(_S_local_capacity))
 466         {
 467           _M_data(_M_create(__n, size_type(0)));
 468           _M_capacity(__n);
 469         }
 470
 471       if (__n)
 472         _S_assign(_M_data(), __n, __c);
 473
 474       _M_set_length(__n);
 475     }
 476
 477   template<typename _CharT, typename _Traits, typename _Alloc>
 478     void
 479     __sso_string_base<_CharT, _Traits, _Alloc>::
 480     _M_assign(const __sso_string_base& __rcs)
 481     {
 482       if (this != &__rcs)
 483         {
 484           const size_type __rsize = __rcs._M_length();
 485           const size_type __capacity = _M_capacity();
 486
 487           if (__rsize > __capacity)
 488             {
 489               size_type __new_capacity = __rsize;
 490               _CharT* __tmp = _M_create(__new_capacity, __capacity);
 491               _M_dispose();
 492               _M_data(__tmp);
 493               _M_capacity(__new_capacity);
 494             }
 495
 496           if (__rsize)
 497             _S_copy(_M_data(), __rcs._M_data(), __rsize);
 498
 499           _M_set_length(__rsize);
 500         }
 501     }
 502
 503   template<typename _CharT, typename _Traits, typename _Alloc>
 504     void
 505     __sso_string_base<_CharT, _Traits, _Alloc>::
 506     _M_reserve(size_type __res)
 507     {
 508       // Make sure we don't shrink below the current size.
 509       if (__res < _M_length())
 510         __res = _M_length();
 511
 512       const size_type __capacity = _M_capacity();
 513       if (__res != __capacity)
 514         {
 515           if (__res > __capacity
 516               || __res > size_type(_S_local_capacity))
 517             {
 518               _CharT* __tmp = _M_create(__res, __capacity);
 519               _S_copy(__tmp, _M_data(), _M_length() + 1);
 520               _M_dispose();
 521               _M_data(__tmp);
 522               _M_capacity(__res);
 523             }
 524           else if (!_M_is_local())
 525             {
 526               _S_copy(_M_local_data, _M_data(), _M_length() + 1);
 527               _M_destroy(__capacity);
 528               _M_data(_M_local_data);
 529             }
 530         }
 531     }
 532
 533   template<typename _CharT, typename _Traits, typename _Alloc>
 534     void
 535     __sso_string_base<_CharT, _Traits, _Alloc>::
 536     _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
 537               const size_type __len2)
 538     {
 539       const size_type __how_much = _M_length() - __pos - __len1;
 540
 541       size_type __new_capacity = _M_length() + __len2 - __len1;
 542       _CharT* __r = _M_create(__new_capacity, _M_capacity());
 543
 544       if (__pos)
 545         _S_copy(__r, _M_data(), __pos);
 546       if (__s && __len2)
 547         _S_copy(__r + __pos, __s, __len2);
 548       if (__how_much)
 549         _S_copy(__r + __pos + __len2,
 550                 _M_data() + __pos + __len1, __how_much);
 551
 552       _M_dispose();
 553       _M_data(__r);
 554       _M_capacity(__new_capacity);
 555     }
 556
 557   template<typename _CharT, typename _Traits, typename _Alloc>
 558     void
 559     __sso_string_base<_CharT, _Traits, _Alloc>::
 560     _M_erase(size_type __pos, size_type __n)
 561     {
 562       const size_type __how_much = _M_length() - __pos - __n;
 563
 564       if (__how_much && __n)
 565         _S_move(_M_data() + __pos, _M_data() + __pos + __n,
 566                 __how_much);
 567
 568       _M_set_length(_M_length() - __n);
 569     }
 570
 571 _GLIBCXX_END_NAMESPACE
 572
 573 #endif /* _SSO_STRING_BASE_H */