libstdc++-v3/include/bits/basic_string.tcc

   1 // Components for manipulating sequences of characters -*- C++ -*-
   2
   3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
   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 2, 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 // You should have received a copy of the GNU General Public License along
  18 // with this library; see the file COPYING.  If not, write to the Free
  19 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  20 // USA.
  21
  22 // As a special exception, you may use this file as part of a free software
  23 // library without restriction.  Specifically, if other files instantiate
  24 // templates or use macros or inline functions from this file, or you compile
  25 // this file and link it with other files to produce an executable, this
  26 // file does not by itself cause the resulting executable to be covered by
  27 // the GNU General Public License.  This exception does not however
  28 // invalidate any other reasons why the executable file might be covered by
  29 // the GNU General Public License.
  30
  31 //
  32 // ISO C++ 14882: 21  Strings library
  33 //
  34
  35 // This file is included by <string>.  It is not meant to be included
  36 // separately.
  37
  38 // Written by Jason Merrill based upon the specification by Takanori Adachi
  39 // in ANSI X3J16/94-0013R2.  Rewritten by Nathan Myers to ISO-14882.
  40
  41 #ifndef _BASIC_STRING_TCC
  42 #define _BASIC_STRING_TCC 1
  43
  44 #pragma GCC system_header
  45
  46 namespace std
  47 {
  48   template<typename _Type>
  49     inline bool
  50     __is_null_pointer(_Type* __ptr)
  51     { return __ptr == 0; }
  52
  53   template<typename _Type>
  54     inline bool
  55     __is_null_pointer(_Type)
  56     { return false; }
  57
  58   template<typename _CharT, typename _Traits, typename _Alloc>
  59     const typename basic_string<_CharT, _Traits, _Alloc>::size_type
  60     basic_string<_CharT, _Traits, _Alloc>::
  61     _Rep::_S_max_size = (((npos - sizeof(_Rep_base))/sizeof(_CharT)) - 1) / 4;
  62
  63   template<typename _CharT, typename _Traits, typename _Alloc>
  64     const _CharT
  65     basic_string<_CharT, _Traits, _Alloc>::
  66     _Rep::_S_terminal = _CharT();
  67
  68   template<typename _CharT, typename _Traits, typename _Alloc>
  69     const typename basic_string<_CharT, _Traits, _Alloc>::size_type
  70     basic_string<_CharT, _Traits, _Alloc>::npos;
  71
  72   // Linker sets _S_empty_rep_storage to all 0s (one reference, empty string)
  73   // at static init time (before static ctors are run).
  74   template<typename _CharT, typename _Traits, typename _Alloc>
  75     typename basic_string<_CharT, _Traits, _Alloc>::size_type
  76     basic_string<_CharT, _Traits, _Alloc>::_Rep::_S_empty_rep_storage[
  77     (sizeof(_Rep_base) + sizeof(_CharT) + sizeof(size_type) - 1) /
  78       sizeof(size_type)];
  79
  80   // NB: This is the special case for Input Iterators, used in
  81   // istreambuf_iterators, etc.
  82   // Input Iterators have a cost structure very different from
  83   // pointers, calling for a different coding style.
  84   template<typename _CharT, typename _Traits, typename _Alloc>
  85     template<typename _InIterator>
  86       _CharT*
  87       basic_string<_CharT, _Traits, _Alloc>::
  88       _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a,
  89                    input_iterator_tag)
  90       {
  91 #ifndef _GLIBCXX_FULLY_DYNAMIC_STRING
  92         if (__beg == __end && __a == _Alloc())
  93           return _S_empty_rep()._M_refdata();
  94 #endif
  95         // Avoid reallocation for common case.
  96         _CharT __buf[128];
  97         size_type __len = 0;
  98         while (__beg != __end && __len < sizeof(__buf) / sizeof(_CharT))
  99           {
 100             __buf[__len++] = *__beg;
 101             ++__beg;
 102           }
 103         _Rep* __r = _Rep::_S_create(__len, size_type(0), __a);
 104         traits_type::copy(__r->_M_refdata(), __buf, __len);
 105         try
 106           {
 107             while (__beg != __end)
 108               {
 109                 if (__len == __r->_M_capacity)
 110                   {
 111                     // Allocate more space.
 112                     _Rep* __another = _Rep::_S_create(__len + 1, __len, __a);
 113                     traits_type::copy(__another->_M_refdata(),
 114                                       __r->_M_refdata(), __len);
 115                     __r->_M_destroy(__a);
 116                     __r = __another;
 117                   }
 118                 __r->_M_refdata()[__len++] = *__beg;
 119                 ++__beg;
 120               }
 121           }
 122         catch(...)
 123           {
 124             __r->_M_destroy(__a);
 125             __throw_exception_again;
 126           }
 127         __r->_M_length = __len;
 128         __r->_M_refdata()[__len] = _Rep::_S_terminal;       // grrr.
 129         return __r->_M_refdata();
 130       }
 131
 132   template<typename _CharT, typename _Traits, typename _Alloc>
 133     template <typename _InIterator>
 134       _CharT*
 135       basic_string<_CharT, _Traits, _Alloc>::
 136       _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a,
 137                    forward_iterator_tag)
 138       {
 139 #ifndef _GLIBCXX_FULLY_DYNAMIC_STRING
 140         if (__beg == __end && __a == _Alloc())
 141           return _S_empty_rep()._M_refdata();
 142 #endif
 143         // NB: Not required, but considered best practice.
 144         if (__builtin_expect(__is_null_pointer(__beg) && __beg != __end, 0))
 145           __throw_logic_error(__N("basic_string::_S_construct NULL not valid"));
 146
 147         const size_type __dnew = static_cast<size_type>(std::distance(__beg,
 148                                                                       __end));
 149         // Check for out_of_range and length_error exceptions.
 150         _Rep* __r = _Rep::_S_create(__dnew, size_type(0), __a);
 151         try
 152           { _S_copy_chars(__r->_M_refdata(), __beg, __end); }
 153         catch(...)
 154           {
 155             __r->_M_destroy(__a);
 156             __throw_exception_again;
 157           }
 158         __r->_M_length = __dnew;
 159         __r->_M_refdata()[__dnew] = _Rep::_S_terminal;  // grrr.
 160         return __r->_M_refdata();
 161       }
 162
 163   template<typename _CharT, typename _Traits, typename _Alloc>
 164     _CharT*
 165     basic_string<_CharT, _Traits, _Alloc>::
 166     _S_construct(size_type __n, _CharT __c, const _Alloc& __a)
 167     {
 168 #ifndef _GLIBCXX_FULLY_DYNAMIC_STRING
 169       if (__n == 0 && __a == _Alloc())
 170         return _S_empty_rep()._M_refdata();
 171 #endif
 172       // Check for out_of_range and length_error exceptions.
 173       _Rep* __r = _Rep::_S_create(__n, size_type(0), __a);
 174       if (__n)
 175         traits_type::assign(__r->_M_refdata(), __n, __c);
 176
 177       __r->_M_length = __n;
 178       __r->_M_refdata()[__n] = _Rep::_S_terminal;  // grrr
 179       return __r->_M_refdata();
 180     }
 181
 182   template<typename _CharT, typename _Traits, typename _Alloc>
 183     basic_string<_CharT, _Traits, _Alloc>::
 184     basic_string(const basic_string& __str)
 185     : _M_dataplus(__str._M_rep()->_M_grab(_Alloc(__str.get_allocator()),
 186                                           __str.get_allocator()),
 187                   __str.get_allocator())
 188     { }
 189
 190   template<typename _CharT, typename _Traits, typename _Alloc>
 191     basic_string<_CharT, _Traits, _Alloc>::
 192     basic_string(const _Alloc& __a)
 193     : _M_dataplus(_S_construct(size_type(), _CharT(), __a), __a)
 194     { }
 195
 196   template<typename _CharT, typename _Traits, typename _Alloc>
 197     basic_string<_CharT, _Traits, _Alloc>::
 198     basic_string(const basic_string& __str, size_type __pos, size_type __n)
 199     : _M_dataplus(_S_construct(__str._M_data()
 200                                + __str._M_check(__pos,
 201                                                 "basic_string::basic_string"),
 202                                __str._M_data() + __str._M_limit(__pos, __n)
 203                                + __pos, _Alloc()), _Alloc())
 204     { }
 205
 206   template<typename _CharT, typename _Traits, typename _Alloc>
 207     basic_string<_CharT, _Traits, _Alloc>::
 208     basic_string(const basic_string& __str, size_type __pos,
 209                  size_type __n, const _Alloc& __a)
 210     : _M_dataplus(_S_construct(__str._M_data()
 211                                + __str._M_check(__pos,
 212                                                 "basic_string::basic_string"),
 213                                __str._M_data() + __str._M_limit(__pos, __n)
 214                                + __pos, __a), __a)
 215     { }
 216
 217   // TBD: DPG annotate
 218   template<typename _CharT, typename _Traits, typename _Alloc>
 219     basic_string<_CharT, _Traits, _Alloc>::
 220     basic_string(const _CharT* __s, size_type __n, const _Alloc& __a)
 221     : _M_dataplus(_S_construct(__s, __s + __n, __a), __a)
 222     { }
 223
 224   // TBD: DPG annotate
 225   template<typename _CharT, typename _Traits, typename _Alloc>
 226     basic_string<_CharT, _Traits, _Alloc>::
 227     basic_string(const _CharT* __s, const _Alloc& __a)
 228     : _M_dataplus(_S_construct(__s, __s ? __s + traits_type::length(__s) :
 229                                __s + npos, __a), __a)
 230     { }
 231
 232   template<typename _CharT, typename _Traits, typename _Alloc>
 233     basic_string<_CharT, _Traits, _Alloc>::
 234     basic_string(size_type __n, _CharT __c, const _Alloc& __a)
 235     : _M_dataplus(_S_construct(__n, __c, __a), __a)
 236     { }
 237
 238   // TBD: DPG annotate
 239   template<typename _CharT, typename _Traits, typename _Alloc>
 240     template<typename _InputIterator>
 241     basic_string<_CharT, _Traits, _Alloc>::
 242     basic_string(_InputIterator __beg, _InputIterator __end, const _Alloc& __a)
 243     : _M_dataplus(_S_construct(__beg, __end, __a), __a)
 244     { }
 245
 246   template<typename _CharT, typename _Traits, typename _Alloc>
 247     basic_string<_CharT, _Traits, _Alloc>&
 248     basic_string<_CharT, _Traits, _Alloc>::
 249     assign(const basic_string& __str)
 250     {
 251       if (_M_rep() != __str._M_rep())
 252         {
 253           // XXX MT
 254           const allocator_type __a = this->get_allocator();
 255           _CharT* __tmp = __str._M_rep()->_M_grab(__a, __str.get_allocator());
 256           _M_rep()->_M_dispose(__a);
 257           _M_data(__tmp);
 258         }
 259       return *this;
 260     }
 261
 262    template<typename _CharT, typename _Traits, typename _Alloc>
 263      basic_string<_CharT, _Traits, _Alloc>&
 264      basic_string<_CharT, _Traits, _Alloc>::
 265      assign(const _CharT* __s, size_type __n)
 266      {
 267        __glibcxx_requires_string_len(__s, __n);
 268        if (__n > this->max_size())
 269          __throw_length_error(__N("basic_string::assign"));
 270        if (_M_rep()->_M_is_shared() || less<const _CharT*>()(__s, _M_data())
 271            || less<const _CharT*>()(_M_data() + this->size(), __s))
 272          return _M_replace_safe(size_type(0), this->size(), __s, __n);
 273        else
 274          {
 275            // Work in-place
 276            const size_type __pos = __s - _M_data();
 277            if (__pos >= __n)
 278              traits_type::copy(_M_data(), __s, __n);
 279            else if (__pos)
 280              traits_type::move(_M_data(), __s, __n);
 281            _M_rep()->_M_set_sharable();
 282            _M_rep()->_M_length = __n;
 283            _M_data()[__n] = _Rep::_S_terminal;  // grr.
 284            return *this;
 285          }
 286      }
 287
 288    template<typename _CharT, typename _Traits, typename _Alloc>
 289      basic_string<_CharT, _Traits, _Alloc>&
 290      basic_string<_CharT, _Traits, _Alloc>::
 291      insert(size_type __pos, const _CharT* __s, size_type __n)
 292      {
 293        __glibcxx_requires_string_len(__s, __n);
 294        _M_check(__pos, "basic_string::insert");
 295        if (this->max_size() - this->size() < __n)
 296          __throw_length_error(__N("basic_string::insert"));
 297        if (_M_rep()->_M_is_shared() || less<const _CharT*>()(__s, _M_data())
 298            || less<const _CharT*>()(_M_data() + this->size(), __s))
 299          return _M_replace_safe(__pos, size_type(0), __s, __n);
 300        else
 301          {
 302            // Work in-place. If _M_mutate reallocates the string, __s
 303            // does not point anymore to valid data, therefore we save its
 304            // offset, then we restore it.
 305            const size_type __off = __s - _M_data();
 306            _M_mutate(__pos, 0, __n);
 307            __s = _M_data() + __off;
 308            _CharT* __p = _M_data() + __pos;
 309            if (__s  + __n <= __p)
 310              traits_type::copy(__p, __s, __n);
 311            else if (__s >= __p)
 312              traits_type::copy(__p, __s + __n, __n);
 313            else
 314              {
 315                const size_type __nleft = __p - __s;
 316                traits_type::copy(__p, __s, __nleft);
 317                traits_type::copy(__p + __nleft, __p + __n, __n - __nleft);
 318              }
 319            return *this;
 320          }
 321      }
 322
 323    template<typename _CharT, typename _Traits, typename _Alloc>
 324      basic_string<_CharT, _Traits, _Alloc>&
 325      basic_string<_CharT, _Traits, _Alloc>::
 326      replace(size_type __pos, size_type __n1, const _CharT* __s,
 327              size_type __n2)
 328      {
 329        __glibcxx_requires_string_len(__s, __n2);
 330        _M_check(__pos, "basic_string::replace");
 331        __n1 = _M_limit(__pos, __n1);
 332        if (this->max_size() - (this->size() - __n1) < __n2)
 333          __throw_length_error(__N("basic_string::replace"));
 334        bool __left;
 335        if (_M_rep()->_M_is_shared() || less<const _CharT*>()(__s, _M_data())
 336            || less<const _CharT*>()(_M_data() + this->size(), __s))
 337          return _M_replace_safe(__pos, __n1, __s, __n2);
 338        else if ((__left = __s + __n2 <= _M_data() + __pos)
 339                 || _M_data() + __pos + __n1 <= __s)
 340          {
 341            // Work in-place: non-overlapping case.
 342            const size_type __off = __s - _M_data();
 343            _M_mutate(__pos, __n1, __n2);
 344            if (__left)
 345              traits_type::copy(_M_data() + __pos,
 346                                _M_data() + __off, __n2);
 347            else
 348              traits_type::copy(_M_data() + __pos,
 349                                _M_data() + __off + __n2 - __n1, __n2);
 350            return *this;
 351          }
 352        else
 353          {
 354            // Todo: overlapping case.
 355            const basic_string __tmp(__s, __n2);
 356            return _M_replace_safe(__pos, __n1, __tmp._M_data(), __n2);
 357          }
 358      }
 359
 360   template<typename _CharT, typename _Traits, typename _Alloc>
 361     void
 362     basic_string<_CharT, _Traits, _Alloc>::_Rep::
 363     _M_destroy(const _Alloc& __a) throw ()
 364     {
 365 #ifndef _GLIBCXX_FULLY_DYNAMIC_STRING
 366       if (this == &_S_empty_rep())
 367         return;
 368 #endif
 369       const size_type __size = sizeof(_Rep_base) +
 370                                (this->_M_capacity + 1) * sizeof(_CharT);
 371       _Raw_bytes_alloc(__a).deallocate(reinterpret_cast<char*>(this), __size);
 372     }
 373
 374   template<typename _CharT, typename _Traits, typename _Alloc>
 375     void
 376     basic_string<_CharT, _Traits, _Alloc>::_M_leak_hard()
 377     {
 378 #ifndef _GLIBCXX_FULLY_DYNAMIC_STRING
 379       if (_M_rep() == &_S_empty_rep())
 380         return;
 381 #endif
 382       if (_M_rep()->_M_is_shared())
 383         _M_mutate(0, 0, 0);
 384       _M_rep()->_M_set_leaked();
 385     }
 386
 387   template<typename _CharT, typename _Traits, typename _Alloc>
 388     void
 389     basic_string<_CharT, _Traits, _Alloc>::
 390     _M_mutate(size_type __pos, size_type __len1, size_type __len2)
 391     {
 392       const size_type __old_size = this->size();
 393       const size_type __new_size = __old_size + __len2 - __len1;
 394       const size_type __how_much = __old_size - __pos - __len1;
 395
 396 #ifndef _GLIBCXX_FULLY_DYNAMIC_STRING
 397       if (_M_rep() == &_S_empty_rep()
 398           || _M_rep()->_M_is_shared() || __new_size > capacity())
 399 #else
 400       if (_M_rep()->_M_is_shared() || __new_size > capacity())
 401 #endif
 402         {
 403           // Must reallocate.
 404           const allocator_type __a = get_allocator();
 405           _Rep* __r = _Rep::_S_create(__new_size, capacity(), __a);
 406
 407           if (__pos)
 408             traits_type::copy(__r->_M_refdata(), _M_data(), __pos);
 409           if (__how_much)
 410             traits_type::copy(__r->_M_refdata() + __pos + __len2,
 411                               _M_data() + __pos + __len1, __how_much);
 412
 413           _M_rep()->_M_dispose(__a);
 414           _M_data(__r->_M_refdata());
 415         }
 416       else if (__how_much && __len1 != __len2)
 417         {
 418           // Work in-place
 419           traits_type::move(_M_data() + __pos + __len2,
 420                             _M_data() + __pos + __len1, __how_much);
 421         }
 422       _M_rep()->_M_set_sharable();
 423       _M_rep()->_M_length = __new_size;
 424       _M_data()[__new_size] = _Rep::_S_terminal; // grrr. (per 21.3.4)
 425       // You cannot leave those LWG people alone for a second.
 426     }
 427
 428   template<typename _CharT, typename _Traits, typename _Alloc>
 429     void
 430     basic_string<_CharT, _Traits, _Alloc>::reserve(size_type __res)
 431     {
 432       if (__res != this->capacity() || _M_rep()->_M_is_shared())
 433         {
 434           if (__res > this->max_size())
 435             __throw_length_error(__N("basic_string::reserve"));
 436           // Make sure we don't shrink below the current size
 437           if (__res < this->size())
 438             __res = this->size();
 439           const allocator_type __a = get_allocator();
 440           _CharT* __tmp = _M_rep()->_M_clone(__a, __res - this->size());
 441           _M_rep()->_M_dispose(__a);
 442           _M_data(__tmp);
 443         }
 444     }
 445
 446   template<typename _CharT, typename _Traits, typename _Alloc>
 447     void basic_string<_CharT, _Traits, _Alloc>::swap(basic_string& __s)
 448     {
 449       if (_M_rep()->_M_is_leaked())
 450         _M_rep()->_M_set_sharable();
 451       if (__s._M_rep()->_M_is_leaked())
 452         __s._M_rep()->_M_set_sharable();
 453       if (this->get_allocator() == __s.get_allocator())
 454         {
 455           _CharT* __tmp = _M_data();
 456           _M_data(__s._M_data());
 457           __s._M_data(__tmp);
 458         }
 459       // The code below can usually be optimized away.
 460       else
 461         {
 462           const basic_string __tmp1(_M_ibegin(), _M_iend(),
 463                                     __s.get_allocator());
 464           const basic_string __tmp2(__s._M_ibegin(), __s._M_iend(),
 465                                     this->get_allocator());
 466           *this = __tmp2;
 467           __s = __tmp1;
 468         }
 469     }
 470
 471   template<typename _CharT, typename _Traits, typename _Alloc>
 472     typename basic_string<_CharT, _Traits, _Alloc>::_Rep*
 473     basic_string<_CharT, _Traits, _Alloc>::_Rep::
 474     _S_create(size_type __capacity, size_type __old_capacity,
 475               const _Alloc& __alloc)
 476     {
 477       typedef basic_string<_CharT, _Traits, _Alloc> __string_type;
 478       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 479       // 83.  String::npos vs. string::max_size()
 480       if (__capacity > _S_max_size)
 481         __throw_length_error(__N("basic_string::_S_create"));
 482
 483       // The standard places no restriction on allocating more memory
 484       // than is strictly needed within this layer at the moment or as
 485       // requested by an explicit application call to reserve().
 486
 487       // Many malloc implementations perform quite poorly when an
 488       // application attempts to allocate memory in a stepwise fashion
 489       // growing each allocation size by only 1 char.  Additionally,
 490       // it makes little sense to allocate less linear memory than the
 491       // natural blocking size of the malloc implementation.
 492       // Unfortunately, we would need a somewhat low-level calculation
 493       // with tuned parameters to get this perfect for any particular
 494       // malloc implementation.  Fortunately, generalizations about
 495       // common features seen among implementations seems to suffice.
 496
 497       // __pagesize need not match the actual VM page size for good
 498       // results in practice, thus we pick a common value on the low
 499       // side.  __malloc_header_size is an estimate of the amount of
 500       // overhead per memory allocation (in practice seen N * sizeof
 501       // (void*) where N is 0, 2 or 4).  According to folklore,
 502       // picking this value on the high side is better than
 503       // low-balling it (especially when this algorithm is used with
 504       // malloc implementations that allocate memory blocks rounded up
 505       // to a size which is a power of 2).
 506       const size_type __pagesize = 4096;
 507       const size_type __malloc_header_size = 4 * sizeof(void*);
 508
 509       // The below implements an exponential growth policy, necessary to
 510       // meet amortized linear time requirements of the library: see
 511       // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
 512       // It's active for allocations requiring an amount of memory above
 513       // system pagesize. This is consistent with the requirements of the
 514       // standard: http://gcc.gnu.org/ml/libstdc++/2001-07/msg00130.html
 515       if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
 516         __capacity = 2 * __old_capacity;
 517
 518       // NB: Need an array of char_type[__capacity], plus a terminating
 519       // null char_type() element, plus enough for the _Rep data structure.
 520       // Whew. Seemingly so needy, yet so elemental.
 521       size_type __size = (__capacity + 1) * sizeof(_CharT) + sizeof(_Rep);
 522
 523       const size_type __adj_size = __size + __malloc_header_size;
 524       if (__adj_size > __pagesize)
 525         {
 526           const size_type __extra = __pagesize - __adj_size % __pagesize;
 527           __capacity += __extra / sizeof(_CharT);
 528           // Never allocate a string bigger than _S_max_size.
 529           if (__capacity > _S_max_size)
 530             __capacity = _S_max_size;
 531           __size = (__capacity + 1) * sizeof(_CharT) + sizeof(_Rep);
 532         }
 533
 534       // NB: Might throw, but no worries about a leak, mate: _Rep()
 535       // does not throw.
 536       void* __place = _Raw_bytes_alloc(__alloc).allocate(__size);
 537       _Rep *__p = new (__place) _Rep;
 538       __p->_M_capacity = __capacity;
 539       __p->_M_set_sharable();  // One reference.
 540       __p->_M_length = 0;
 541       return __p;
 542     }
 543
 544   template<typename _CharT, typename _Traits, typename _Alloc>
 545     _CharT*
 546     basic_string<_CharT, _Traits, _Alloc>::_Rep::
 547     _M_clone(const _Alloc& __alloc, size_type __res)
 548     {
 549       // Requested capacity of the clone.
 550       const size_type __requested_cap = this->_M_length + __res;
 551       _Rep* __r = _Rep::_S_create(__requested_cap, this->_M_capacity,
 552                                   __alloc);
 553       if (this->_M_length)
 554         traits_type::copy(__r->_M_refdata(), _M_refdata(),
 555                           this->_M_length);
 556
 557       __r->_M_length = this->_M_length;
 558       __r->_M_refdata()[this->_M_length] = _Rep::_S_terminal;
 559       return __r->_M_refdata();
 560     }
 561
 562   template<typename _CharT, typename _Traits, typename _Alloc>
 563     void
 564     basic_string<_CharT, _Traits, _Alloc>::resize(size_type __n, _CharT __c)
 565     {
 566       if (__n > max_size())
 567         __throw_length_error(__N("basic_string::resize"));
 568       const size_type __size = this->size();
 569       if (__size < __n)
 570         this->append(__n - __size, __c);
 571       else if (__n < __size)
 572         this->erase(__n);
 573       // else nothing (in particular, avoid calling _M_mutate() unnecessarily.)
 574     }
 575
 576   template<typename _CharT, typename _Traits, typename _Alloc>
 577     template<typename _InputIterator>
 578       basic_string<_CharT, _Traits, _Alloc>&
 579       basic_string<_CharT, _Traits, _Alloc>::
 580       _M_replace_dispatch(iterator __i1, iterator __i2, _InputIterator __k1,
 581                           _InputIterator __k2, __false_type)
 582       {
 583         const basic_string __s(__k1, __k2);
 584         const size_type __n1 = __i2 - __i1;
 585         if (this->max_size() - (this->size() - __n1) < __s.size())
 586           __throw_length_error(__N("basic_string::_M_replace_dispatch"));
 587         return _M_replace_safe(__i1 - _M_ibegin(), __n1, __s._M_data(),
 588                                __s.size());
 589       }
 590
 591   template<typename _CharT, typename _Traits, typename _Alloc>
 592     basic_string<_CharT, _Traits, _Alloc>&
 593     basic_string<_CharT, _Traits, _Alloc>::
 594     append(const basic_string& __str)
 595     {
 596       // Iff appending itself, string needs to pre-reserve the
 597       // correct size so that _M_mutate does not clobber the
 598       // pointer __str._M_data() formed here.
 599       const size_type __size = __str.size();
 600       const size_type __len = __size + this->size();
 601       if (__len > this->capacity())
 602         this->reserve(__len);
 603       return _M_replace_safe(this->size(), size_type(0), __str._M_data(),
 604                              __str.size());
 605     }
 606
 607   template<typename _CharT, typename _Traits, typename _Alloc>
 608     basic_string<_CharT, _Traits, _Alloc>&
 609     basic_string<_CharT, _Traits, _Alloc>::
 610     append(const basic_string& __str, size_type __pos, size_type __n)
 611     {
 612       // Iff appending itself, string needs to pre-reserve the
 613       // correct size so that _M_mutate does not clobber the
 614       // pointer __str._M_data() formed here.
 615       __str._M_check(__pos, "basic_string::append");
 616       __n = __str._M_limit(__pos, __n);
 617       const size_type __len = __n + this->size();
 618       if (__len > this->capacity())
 619         this->reserve(__len);
 620       return _M_replace_safe(this->size(), size_type(0), __str._M_data()
 621                              + __pos, __n);
 622     }
 623
 624   template<typename _CharT, typename _Traits, typename _Alloc>
 625     basic_string<_CharT, _Traits, _Alloc>&
 626     basic_string<_CharT, _Traits, _Alloc>::
 627     append(const _CharT* __s, size_type __n)
 628     {
 629       __glibcxx_requires_string_len(__s, __n);
 630       const size_type __len = __n + this->size();
 631       if (__len > this->capacity())
 632         this->reserve(__len);
 633       return _M_replace_safe(this->size(), size_type(0), __s, __n);
 634     }
 635
 636   template<typename _CharT, typename _Traits, typename _Alloc>
 637     basic_string<_CharT, _Traits, _Alloc>
 638     operator+(const _CharT* __lhs,
 639               const basic_string<_CharT, _Traits, _Alloc>& __rhs)
 640     {
 641       __glibcxx_requires_string(__lhs);
 642       typedef basic_string<_CharT, _Traits, _Alloc> __string_type;
 643       typedef typename __string_type::size_type   __size_type;
 644       const __size_type __len = _Traits::length(__lhs);
 645       __string_type __str;
 646       __str.reserve(__len + __rhs.size());
 647       __str.append(__lhs, __len);
 648       __str.append(__rhs);
 649       return __str;
 650     }
 651
 652   template<typename _CharT, typename _Traits, typename _Alloc>
 653     basic_string<_CharT, _Traits, _Alloc>
 654     operator+(_CharT __lhs, const basic_string<_CharT, _Traits, _Alloc>& __rhs)
 655     {
 656       typedef basic_string<_CharT, _Traits, _Alloc> __string_type;
 657       typedef typename __string_type::size_type   __size_type;
 658       __string_type __str;
 659       const __size_type __len = __rhs.size();
 660       __str.reserve(__len + 1);
 661       __str.append(__size_type(1), __lhs);
 662       __str.append(__rhs);
 663       return __str;
 664     }
 665
 666   template<typename _CharT, typename _Traits, typename _Alloc>
 667     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 668     basic_string<_CharT, _Traits, _Alloc>::
 669     copy(_CharT* __s, size_type __n, size_type __pos) const
 670     {
 671       _M_check(__pos, "basic_string::copy");
 672       __n = _M_limit(__pos, __n);
 673       __glibcxx_requires_string_len(__s, __n);
 674       if (__n)
 675         traits_type::copy(__s, _M_data() + __pos, __n);
 676       // 21.3.5.7 par 3: do not append null.  (good.)
 677       return __n;
 678     }
 679
 680   template<typename _CharT, typename _Traits, typename _Alloc>
 681     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 682     basic_string<_CharT, _Traits, _Alloc>::
 683     find(const _CharT* __s, size_type __pos, size_type __n) const
 684     {
 685       __glibcxx_requires_string_len(__s, __n);
 686       size_type __ret = npos;
 687       const size_type __size = this->size();
 688       if (__pos + __n <= __size)
 689         {
 690           const _CharT* __data = _M_data();
 691           const _CharT* __p = std::search(__data + __pos, __data + __size,
 692                                           __s, __s + __n, traits_type::eq);
 693           if (__p != __data + __size || __n == 0)
 694             __ret = __p - __data;
 695         }
 696       return __ret;
 697     }
 698
 699   template<typename _CharT, typename _Traits, typename _Alloc>
 700     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 701     basic_string<_CharT, _Traits, _Alloc>::
 702     find(_CharT __c, size_type __pos) const
 703     {
 704       size_type __ret = npos;
 705       const size_type __size = this->size();
 706       if (__pos < __size)
 707         {
 708           const _CharT* __data = _M_data();
 709           const size_type __n = __size - __pos;
 710           const _CharT* __p = traits_type::find(__data + __pos, __n, __c);
 711           if (__p)
 712             __ret = __p - __data;
 713         }
 714       return __ret;
 715     }
 716
 717   template<typename _CharT, typename _Traits, typename _Alloc>
 718     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 719     basic_string<_CharT, _Traits, _Alloc>::
 720     rfind(const _CharT* __s, size_type __pos, size_type __n) const
 721     {
 722       __glibcxx_requires_string_len(__s, __n);
 723       const size_type __size = this->size();
 724       if (__n <= __size)
 725         {
 726           __pos = std::min(size_type(__size - __n), __pos);
 727           const _CharT* __data = _M_data();
 728           do
 729             {
 730               if (traits_type::compare(__data + __pos, __s, __n) == 0)
 731                 return __pos;
 732             }
 733           while (__pos-- > 0);
 734         }
 735       return npos;
 736     }
 737
 738   template<typename _CharT, typename _Traits, typename _Alloc>
 739     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 740     basic_string<_CharT, _Traits, _Alloc>::
 741     rfind(_CharT __c, size_type __pos) const
 742     {
 743       size_type __size = this->size();
 744       if (__size)
 745         {
 746           if (--__size > __pos)
 747             __size = __pos;
 748           for (++__size; __size-- > 0; )
 749             if (traits_type::eq(_M_data()[__size], __c))
 750               return __size;
 751         }
 752       return npos;
 753     }
 754
 755   template<typename _CharT, typename _Traits, typename _Alloc>
 756     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 757     basic_string<_CharT, _Traits, _Alloc>::
 758     find_first_of(const _CharT* __s, size_type __pos, size_type __n) const
 759     {
 760       __glibcxx_requires_string_len(__s, __n);
 761       for (; __n && __pos < this->size(); ++__pos)
 762         {
 763           const _CharT* __p = traits_type::find(__s, __n, _M_data()[__pos]);
 764           if (__p)
 765             return __pos;
 766         }
 767       return npos;
 768     }
 769
 770   template<typename _CharT, typename _Traits, typename _Alloc>
 771     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 772     basic_string<_CharT, _Traits, _Alloc>::
 773     find_last_of(const _CharT* __s, size_type __pos, size_type __n) const
 774     {
 775       __glibcxx_requires_string_len(__s, __n);
 776       size_type __size = this->size();
 777       if (__size && __n)
 778         {
 779           if (--__size > __pos)
 780             __size = __pos;
 781           do
 782             {
 783               if (traits_type::find(__s, __n, _M_data()[__size]))
 784                 return __size;
 785             }
 786           while (__size-- != 0);
 787         }
 788       return npos;
 789     }
 790
 791   template<typename _CharT, typename _Traits, typename _Alloc>
 792     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 793     basic_string<_CharT, _Traits, _Alloc>::
 794     find_first_not_of(const _CharT* __s, size_type __pos, size_type __n) const
 795     {
 796       __glibcxx_requires_string_len(__s, __n);
 797       for (; __pos < this->size(); ++__pos)
 798         if (!traits_type::find(__s, __n, _M_data()[__pos]))
 799           return __pos;
 800       return npos;
 801     }
 802
 803   template<typename _CharT, typename _Traits, typename _Alloc>
 804     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 805     basic_string<_CharT, _Traits, _Alloc>::
 806     find_first_not_of(_CharT __c, size_type __pos) const
 807     {
 808       for (; __pos < this->size(); ++__pos)
 809         if (!traits_type::eq(_M_data()[__pos], __c))
 810           return __pos;
 811       return npos;
 812     }
 813
 814   template<typename _CharT, typename _Traits, typename _Alloc>
 815     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 816     basic_string<_CharT, _Traits, _Alloc>::
 817     find_last_not_of(const _CharT* __s, size_type __pos, size_type __n) const
 818     {
 819       __glibcxx_requires_string_len(__s, __n);
 820       size_type __size = this->size();
 821       if (__size)
 822         {
 823           if (--__size > __pos)
 824             __size = __pos;
 825           do
 826             {
 827               if (!traits_type::find(__s, __n, _M_data()[__size]))
 828                 return __size;
 829             }
 830           while (__size--);
 831         }
 832       return npos;
 833     }
 834
 835   template<typename _CharT, typename _Traits, typename _Alloc>
 836     typename basic_string<_CharT, _Traits, _Alloc>::size_type
 837     basic_string<_CharT, _Traits, _Alloc>::
 838     find_last_not_of(_CharT __c, size_type __pos) const
 839     {
 840       size_type __size = this->size();
 841       if (__size)
 842         {
 843           if (--__size > __pos)
 844             __size = __pos;
 845           do
 846             {
 847               if (!traits_type::eq(_M_data()[__size], __c))
 848                 return __size;
 849             }
 850           while (__size--);
 851         }
 852       return npos;
 853     }
 854
 855   template<typename _CharT, typename _Traits, typename _Alloc>
 856     int
 857     basic_string<_CharT, _Traits, _Alloc>::
 858     compare(size_type __pos, size_type __n, const basic_string& __str) const
 859     {
 860       _M_check(__pos, "basic_string::compare");
 861       __n = _M_limit(__pos, __n);
 862       const size_type __osize = __str.size();
 863       const size_type __len = std::min(__n, __osize);
 864       int __r = traits_type::compare(_M_data() + __pos, __str.data(), __len);
 865       if (!__r)
 866         __r = __n - __osize;
 867       return __r;
 868     }
 869
 870   template<typename _CharT, typename _Traits, typename _Alloc>
 871     int
 872     basic_string<_CharT, _Traits, _Alloc>::
 873     compare(size_type __pos1, size_type __n1, const basic_string& __str,
 874             size_type __pos2, size_type __n2) const
 875     {
 876       _M_check(__pos1, "basic_string::compare");
 877       __str._M_check(__pos2, "basic_string::compare");
 878       __n1 = _M_limit(__pos1, __n1);
 879       __n2 = __str._M_limit(__pos2, __n2);
 880       const size_type __len = std::min(__n1, __n2);
 881       int __r = traits_type::compare(_M_data() + __pos1,
 882                                      __str.data() + __pos2, __len);
 883       if (!__r)
 884         __r = __n1 - __n2;
 885       return __r;
 886     }
 887
 888   template<typename _CharT, typename _Traits, typename _Alloc>
 889     int
 890     basic_string<_CharT, _Traits, _Alloc>::
 891     compare(const _CharT* __s) const
 892     {
 893       __glibcxx_requires_string(__s);
 894       const size_type __size = this->size();
 895       const size_type __osize = traits_type::length(__s);
 896       const size_type __len = std::min(__size, __osize);
 897       int __r = traits_type::compare(_M_data(), __s, __len);
 898       if (!__r)
 899         __r = __size - __osize;
 900       return __r;
 901     }
 902
 903   template<typename _CharT, typename _Traits, typename _Alloc>
 904     int
 905     basic_string <_CharT, _Traits, _Alloc>::
 906     compare(size_type __pos, size_type __n1, const _CharT* __s) const
 907     {
 908       __glibcxx_requires_string(__s);
 909       _M_check(__pos, "basic_string::compare");
 910       __n1 = _M_limit(__pos, __n1);
 911       const size_type __osize = traits_type::length(__s);
 912       const size_type __len = std::min(__n1, __osize);
 913       int __r = traits_type::compare(_M_data() + __pos, __s, __len);
 914       if (!__r)
 915         __r = __n1 - __osize;
 916       return __r;
 917     }
 918
 919   template<typename _CharT, typename _Traits, typename _Alloc>
 920     int
 921     basic_string <_CharT, _Traits, _Alloc>::
 922     compare(size_type __pos, size_type __n1, const _CharT* __s,
 923             size_type __n2) const
 924     {
 925       __glibcxx_requires_string_len(__s, __n2);
 926       _M_check(__pos, "basic_string::compare");
 927       __n1 = _M_limit(__pos, __n1);
 928       const size_type __len = std::min(__n1, __n2);
 929       int __r = traits_type::compare(_M_data() + __pos, __s, __len);
 930       if (!__r)
 931         __r = __n1 - __n2;
 932       return __r;
 933     }
 934
 935   // Inhibit implicit instantiations for required instantiations,
 936   // which are defined via explicit instantiations elsewhere.
 937   // NB: This syntax is a GNU extension.
 938 #if _GLIBCXX_EXTERN_TEMPLATE
 939   extern template class basic_string<char>;
 940   extern template
 941     basic_istream<char>&
 942     operator>>(basic_istream<char>&, string&);
 943   extern template
 944     basic_ostream<char>&
 945     operator<<(basic_ostream<char>&, const string&);
 946   extern template
 947     basic_istream<char>&
 948     getline(basic_istream<char>&, string&, char);
 949   extern template
 950     basic_istream<char>&
 951     getline(basic_istream<char>&, string&);
 952
 953 #ifdef _GLIBCXX_USE_WCHAR_T
 954   extern template class basic_string<wchar_t>;
 955   extern template
 956     basic_istream<wchar_t>&
 957     operator>>(basic_istream<wchar_t>&, wstring&);
 958   extern template
 959     basic_ostream<wchar_t>&
 960     operator<<(basic_ostream<wchar_t>&, const wstring&);
 961   extern template
 962     basic_istream<wchar_t>&
 963     getline(basic_istream<wchar_t>&, wstring&, wchar_t);
 964   extern template
 965     basic_istream<wchar_t>&
 966     getline(basic_istream<wchar_t>&, wstring&);
 967 #endif
 968 #endif
 969 } // namespace std
 970
 971 #endif