libstdc++
sso_string_base.h
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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,
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,
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,
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  this->_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,
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  { this->_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  this->_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  this->_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  this->_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  this->_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  this->_S_copy(__r, _M_data(), __pos);
550  if (__s && __len2)
551  this->_S_copy(__r + __pos, __s, __len2);
552  if (__how_much)
553  this->_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  this->_S_move(_M_data() + __pos, _M_data() + __pos + __n, __how_much);
570 
571  _M_set_length(_M_length() - __n);
572  }
573 
574 _GLIBCXX_END_NAMESPACE_VERSION
575 } // namespace
576 
577 #endif /* _SSO_STRING_BASE_H */
Forward iterators support a superset of input iterator operations.
iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
Marking input iterators.