1 // Short-string-optimized versatile string base -*- C++ -*-
3 // Copyright (C) 2005 Free Software Foundation, Inc.
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)
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.
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,
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.
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.
36 #ifndef _SSO_STRING_BASE_H
37 #define _SSO_STRING_BASE_H 1
41 template<typename _CharT, typename _Traits, typename _Alloc>
42 class __sso_string_base
43 : protected __vstring_utility<_CharT, _Traits, _Alloc>
46 typedef _Traits traits_type;
47 typedef typename _Traits::char_type value_type;
48 typedef _Alloc allocator_type;
50 typedef __vstring_utility<_CharT, _Traits, _Alloc> _Util_Base;
51 typedef typename _Util_Base::_CharT_alloc_type _CharT_alloc_type;
52 typedef typename _CharT_alloc_type::size_type size_type;
55 // The maximum number of individual char_type elements of an
56 // individual string is determined by _S_max_size. This is the
57 // value that will be returned by max_size(). (Whereas npos
58 // is the maximum number of bytes the allocator can allocate.)
59 // If one was to divvy up the theoretical largest size string,
60 // with a terminating character and m _CharT elements, it'd
62 // npos = m * sizeof(_CharT) + sizeof(_CharT)
64 // m = npos / sizeof(_CharT) - 1
65 // In addition, this implementation quarters this amount.
66 enum { _S_max_size = (((static_cast<size_type>(-1)
67 / sizeof(_CharT)) - 1) / 4) };
69 // Data Members (private):
70 typename _Util_Base::template _Alloc_hider<_Alloc> _M_dataplus;
71 size_type _M_string_length;
73 enum { _S_local_capacity = 15 };
77 _CharT _M_local_data[_S_local_capacity + 1];
78 size_type _M_allocated_capacity;
83 { _M_dataplus._M_p = __p; }
86 _M_length(size_type __length)
87 { _M_string_length = __length; }
90 _M_capacity(size_type __capacity)
91 { _M_allocated_capacity = __capacity; }
95 { return _M_data() == _M_local_data; }
99 _M_create(size_type&, size_type);
105 _M_destroy(_M_allocated_capacity + 1);
109 _M_destroy(size_type) throw();
111 // _M_construct_aux is used to implement the 21.3.1 para 15 which
112 // requires special behaviour if _InIterator is an integral type
113 template<typename _InIterator>
115 _M_construct_aux(_InIterator __beg, _InIterator __end, __false_type)
117 typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
118 _M_construct(__beg, __end, _Tag());
121 template<typename _InIterator>
123 _M_construct_aux(_InIterator __beg, _InIterator __end, __true_type)
124 { _M_construct(static_cast<size_type>(__beg),
125 static_cast<value_type>(__end)); }
127 template<typename _InIterator>
129 _M_construct(_InIterator __beg, _InIterator __end)
131 typedef typename std::__is_integer<_InIterator>::__type _Integral;
132 _M_construct_aux(__beg, __end, _Integral());
135 // For Input Iterators, used in istreambuf_iterators, etc.
136 template<typename _InIterator>
138 _M_construct(_InIterator __beg, _InIterator __end,
139 std::input_iterator_tag);
141 // For forward_iterators up to random_access_iterators, used for
142 // string::iterator, _CharT*, etc.
143 template<typename _FwdIterator>
145 _M_construct(_FwdIterator __beg, _FwdIterator __end,
146 std::forward_iterator_tag);
149 _M_construct(size_type __req, _CharT __c);
154 { return size_type(_S_max_size); }
158 { return _M_dataplus._M_p; }
162 { return _M_string_length; }
167 return _M_is_local() ? size_type(_S_local_capacity)
168 : _M_allocated_capacity;
182 _M_set_length(size_type __n)
185 traits_type::assign(_M_data()[__n], _CharT());
189 : _M_dataplus(_Alloc(), _M_local_data)
190 { _M_set_length(0); }
192 __sso_string_base(const _Alloc& __a);
194 __sso_string_base(const __sso_string_base& __rcs);
196 __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a);
198 template<typename _InputIterator>
199 __sso_string_base(_InputIterator __beg, _InputIterator __end,
207 { return _M_dataplus; }
209 const allocator_type&
210 _M_get_allocator() const
211 { return _M_dataplus; }
214 _M_swap(__sso_string_base& __rcs);
217 _M_assign(const __sso_string_base& __rcs);
220 _M_reserve(size_type __res);
223 _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
227 _M_erase(size_type __pos, size_type __n);
230 template<typename _CharT, typename _Traits, typename _Alloc>
232 __sso_string_base<_CharT, _Traits, _Alloc>::
233 _M_destroy(size_type __size) throw()
234 { _CharT_alloc_type(_M_get_allocator()).deallocate(_M_data(), __size); }
236 template<typename _CharT, typename _Traits, typename _Alloc>
238 __sso_string_base<_CharT, _Traits, _Alloc>::
239 _M_swap(__sso_string_base& __rcs)
241 // NB: Implement Option 3 of DR 431 (see N1599).
242 _M_dataplus._M_alloc_swap(__rcs._M_dataplus);
245 if (__rcs._M_is_local())
247 if (_M_length() && __rcs._M_length())
249 _CharT __tmp_data[_S_local_capacity + 1];
250 traits_type::copy(__tmp_data, __rcs._M_local_data,
251 _S_local_capacity + 1);
252 traits_type::copy(__rcs._M_local_data, _M_local_data,
253 _S_local_capacity + 1);
254 traits_type::copy(_M_local_data, __tmp_data,
255 _S_local_capacity + 1);
257 else if (__rcs._M_length())
259 traits_type::copy(_M_local_data, __rcs._M_local_data,
260 _S_local_capacity + 1);
261 _M_length(__rcs._M_length());
262 __rcs._M_set_length(0);
265 else if (_M_length())
267 traits_type::copy(__rcs._M_local_data, _M_local_data,
268 _S_local_capacity + 1);
269 __rcs._M_length(_M_length());
276 const size_type __tmp_capacity = __rcs._M_allocated_capacity;
277 traits_type::copy(__rcs._M_local_data, _M_local_data,
278 _S_local_capacity + 1);
279 _M_data(__rcs._M_data());
280 __rcs._M_data(__rcs._M_local_data);
281 _M_capacity(__tmp_capacity);
285 const size_type __tmp_capacity = _M_allocated_capacity;
286 if (__rcs._M_is_local())
288 traits_type::copy(_M_local_data, __rcs._M_local_data,
289 _S_local_capacity + 1);
290 __rcs._M_data(_M_data());
291 _M_data(_M_local_data);
295 _CharT* __tmp_ptr = _M_data();
296 _M_data(__rcs._M_data());
297 __rcs._M_data(__tmp_ptr);
298 _M_capacity(__rcs._M_allocated_capacity);
300 __rcs._M_capacity(__tmp_capacity);
303 const size_type __tmp_length = _M_length();
304 _M_length(__rcs._M_length());
305 __rcs._M_length(__tmp_length);
308 template<typename _CharT, typename _Traits, typename _Alloc>
310 __sso_string_base<_CharT, _Traits, _Alloc>::
311 _M_create(size_type& __capacity, size_type __old_capacity)
313 // _GLIBCXX_RESOLVE_LIB_DEFECTS
314 // 83. String::npos vs. string::max_size()
315 if (__capacity > size_type(_S_max_size))
316 std::__throw_length_error(__N("__sso_string_base::_M_create"));
318 // The below implements an exponential growth policy, necessary to
319 // meet amortized linear time requirements of the library: see
320 // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.
321 if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)
322 __capacity = 2 * __old_capacity;
324 // NB: Need an array of char_type[__capacity], plus a terminating
325 // null char_type() element.
326 return _CharT_alloc_type(_M_get_allocator()).allocate(__capacity + 1);
329 template<typename _CharT, typename _Traits, typename _Alloc>
330 __sso_string_base<_CharT, _Traits, _Alloc>::
331 __sso_string_base(const _Alloc& __a)
332 : _M_dataplus(__a, _M_local_data)
333 { _M_set_length(0); }
335 template<typename _CharT, typename _Traits, typename _Alloc>
336 __sso_string_base<_CharT, _Traits, _Alloc>::
337 __sso_string_base(const __sso_string_base& __rcs)
338 : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
339 { _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
341 template<typename _CharT, typename _Traits, typename _Alloc>
342 __sso_string_base<_CharT, _Traits, _Alloc>::
343 __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
344 : _M_dataplus(__a, _M_local_data)
345 { _M_construct(__n, __c); }
347 template<typename _CharT, typename _Traits, typename _Alloc>
348 template<typename _InputIterator>
349 __sso_string_base<_CharT, _Traits, _Alloc>::
350 __sso_string_base(_InputIterator __beg, _InputIterator __end,
352 : _M_dataplus(__a, _M_local_data)
353 { _M_construct(__beg, __end); }
355 // NB: This is the special case for Input Iterators, used in
356 // istreambuf_iterators, etc.
357 // Input Iterators have a cost structure very different from
358 // pointers, calling for a different coding style.
359 template<typename _CharT, typename _Traits, typename _Alloc>
360 template<typename _InIterator>
362 __sso_string_base<_CharT, _Traits, _Alloc>::
363 _M_construct(_InIterator __beg, _InIterator __end,
364 std::input_iterator_tag)
367 size_type __capacity = size_type(_S_local_capacity);
369 while (__beg != __end && __len < __capacity)
371 _M_data()[__len++] = *__beg;
377 while (__beg != __end)
379 if (__len == __capacity)
381 // Allocate more space.
382 __capacity = __len + 1;
383 _CharT* __another = _M_create(__capacity, __len);
384 _S_copy(__another, _M_data(), __len);
387 _M_capacity(__capacity);
389 _M_data()[__len++] = *__beg;
396 __throw_exception_again;
399 _M_set_length(__len);
402 template<typename _CharT, typename _Traits, typename _Alloc>
403 template<typename _InIterator>
405 __sso_string_base<_CharT, _Traits, _Alloc>::
406 _M_construct(_InIterator __beg, _InIterator __end,
407 std::forward_iterator_tag)
409 // NB: Not required, but considered best practice.
410 if (__builtin_expect(_S_is_null_pointer(__beg) && __beg != __end, 0))
411 std::__throw_logic_error(__N("__sso_string_base::"
412 "_M_construct NULL not valid"));
414 size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
416 if (__dnew > size_type(_S_local_capacity))
418 _M_data(_M_create(__dnew, size_type(0)));
422 // Check for out_of_range and length_error exceptions.
424 { _S_copy_chars(_M_data(), __beg, __end); }
428 __throw_exception_again;
431 _M_set_length(__dnew);
434 template<typename _CharT, typename _Traits, typename _Alloc>
436 __sso_string_base<_CharT, _Traits, _Alloc>::
437 _M_construct(size_type __n, _CharT __c)
439 if (__n > size_type(_S_local_capacity))
441 _M_data(_M_create(__n, size_type(0)));
446 _S_assign(_M_data(), __n, __c);
451 template<typename _CharT, typename _Traits, typename _Alloc>
453 __sso_string_base<_CharT, _Traits, _Alloc>::
454 _M_assign(const __sso_string_base& __rcs)
458 size_type __size = __rcs._M_length();
460 _CharT* __tmp = _M_local_data;
461 if (__size > size_type(_S_local_capacity))
462 __tmp = _M_create(__size, size_type(0));
468 _S_copy(_M_data(), __rcs._M_data(), __size);
473 _M_set_length(__size);
477 template<typename _CharT, typename _Traits, typename _Alloc>
479 __sso_string_base<_CharT, _Traits, _Alloc>::
480 _M_reserve(size_type __res)
482 // Make sure we don't shrink below the current size.
483 if (__res < _M_length())
486 const size_type __capacity = _M_capacity();
487 if (__res != __capacity)
489 if (__res > __capacity
490 || __res > size_type(_S_local_capacity))
492 _CharT* __tmp = _M_create(__res, __capacity);
493 _S_copy(__tmp, _M_data(), _M_length() + 1);
498 else if (!_M_is_local())
500 const size_type __tmp_capacity = _M_allocated_capacity;
501 _S_copy(_M_local_data, _M_data(), _M_length() + 1);
502 _M_destroy(__tmp_capacity + 1);
503 _M_data(_M_local_data);
508 template<typename _CharT, typename _Traits, typename _Alloc>
510 __sso_string_base<_CharT, _Traits, _Alloc>::
511 _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
512 const size_type __len2)
514 const size_type __how_much = _M_length() - __pos - __len1;
516 size_type __new_capacity = _M_length() + __len2 - __len1;
517 _CharT* __r = _M_create(__new_capacity, _M_capacity());
520 _S_copy(__r, _M_data(), __pos);
522 _S_copy(__r + __pos, __s, __len2);
524 _S_copy(__r + __pos + __len2,
525 _M_data() + __pos + __len1, __how_much);
529 _M_capacity(__new_capacity);
532 template<typename _CharT, typename _Traits, typename _Alloc>
534 __sso_string_base<_CharT, _Traits, _Alloc>::
535 _M_erase(size_type __pos, size_type __n)
537 const size_type __how_much = _M_length() - __pos - __n;
539 if (__how_much && __n)
540 _S_move(_M_data() + __pos, _M_data() + __pos + __n,
543 _M_set_length(_M_length() - __n);
545 } // namespace __gnu_cxx
547 #endif /* _SSO_STRING_BASE_H */