libstdc++
sso_string_base.h
Go to the documentation of this file.
1 // Short-string-optimized versatile string base -*- C++ -*-
2 
3 // Copyright (C) 2005-2014 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 3, 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 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file ext/sso_string_base.h
26  * This is an internal header file, included by other library headers.
27  * Do not attempt to use it directly. @headername{ext/vstring.h}
28  */
29 
30 #ifndef _SSO_STRING_BASE_H
31 #define _SSO_STRING_BASE_H 1
32 
33 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
34 {
35 _GLIBCXX_BEGIN_NAMESPACE_VERSION
36 
37  template<typename _CharT, typename _Traits, typename _Alloc>
38  class __sso_string_base
39  : protected __vstring_utility<_CharT, _Traits, _Alloc>
40  {
41  public:
42  typedef _Traits traits_type;
43  typedef typename _Traits::char_type value_type;
44 
45  typedef __vstring_utility<_CharT, _Traits, _Alloc> _Util_Base;
46  typedef typename _Util_Base::_CharT_alloc_type _CharT_alloc_type;
47  typedef typename _CharT_alloc_type::size_type size_type;
48 
49  private:
50  // Data Members:
51  typename _Util_Base::template _Alloc_hider<_CharT_alloc_type>
52  _M_dataplus;
53  size_type _M_string_length;
54 
55  enum { _S_local_capacity = 15 };
56 
57  union
58  {
59  _CharT _M_local_data[_S_local_capacity + 1];
60  size_type _M_allocated_capacity;
61  };
62 
63  void
64  _M_data(_CharT* __p)
65  { _M_dataplus._M_p = __p; }
66 
67  void
68  _M_length(size_type __length)
69  { _M_string_length = __length; }
70 
71  void
72  _M_capacity(size_type __capacity)
73  { _M_allocated_capacity = __capacity; }
74 
75  bool
76  _M_is_local() const
77  { return _M_data() == _M_local_data; }
78 
79  // Create & Destroy
80  _CharT*
81  _M_create(size_type&, size_type);
82 
83  void
84  _M_dispose()
85  {
86  if (!_M_is_local())
87  _M_destroy(_M_allocated_capacity);
88  }
89 
90  void
91  _M_destroy(size_type __size) throw()
92  { _M_get_allocator().deallocate(_M_data(), __size + 1); }
93 
94  // _M_construct_aux is used to implement the 21.3.1 para 15 which
95  // requires special behaviour if _InIterator is an integral type
96  template<typename _InIterator>
97  void
98  _M_construct_aux(_InIterator __beg, _InIterator __end,
99  std::__false_type)
100  {
101  typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
102  _M_construct(__beg, __end, _Tag());
103  }
104 
105  // _GLIBCXX_RESOLVE_LIB_DEFECTS
106  // 438. Ambiguity in the "do the right thing" clause
107  template<typename _Integer>
108  void
109  _M_construct_aux(_Integer __beg, _Integer __end, std::__true_type)
110  { _M_construct_aux_2(static_cast<size_type>(__beg), __end); }
111 
112  void
113  _M_construct_aux_2(size_type __req, _CharT __c)
114  { _M_construct(__req, __c); }
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,
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,
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 #if __cplusplus >= 201103L
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  if (this == &__rcs)
237  return;
238 
239  // _GLIBCXX_RESOLVE_LIB_DEFECTS
240  // 431. Swapping containers with unequal allocators.
241  std::__alloc_swap<_CharT_alloc_type>::_S_do_it(_M_get_allocator(),
242  __rcs._M_get_allocator());
243 
244  if (_M_is_local())
245  if (__rcs._M_is_local())
246  {
247  if (_M_length() && __rcs._M_length())
248  {
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);
256  }
257  else if (__rcs._M_length())
258  {
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);
263  return;
264  }
265  else if (_M_length())
266  {
267  traits_type::copy(__rcs._M_local_data, _M_local_data,
268  _S_local_capacity + 1);
269  __rcs._M_length(_M_length());
270  _M_set_length(0);
271  return;
272  }
273  }
274  else
275  {
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);
282  }
283  else
284  {
285  const size_type __tmp_capacity = _M_allocated_capacity;
286  if (__rcs._M_is_local())
287  {
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);
292  }
293  else
294  {
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);
299  }
300  __rcs._M_capacity(__tmp_capacity);
301  }
302 
303  const size_type __tmp_length = _M_length();
304  _M_length(__rcs._M_length());
305  __rcs._M_length(__tmp_length);
306  }
307 
308  template<typename _CharT, typename _Traits, typename _Alloc>
309  _CharT*
310  __sso_string_base<_CharT, _Traits, _Alloc>::
311  _M_create(size_type& __capacity, size_type __old_capacity)
312  {
313  // _GLIBCXX_RESOLVE_LIB_DEFECTS
314  // 83. String::npos vs. string::max_size()
315  if (__capacity > _M_max_size())
316  std::__throw_length_error(__N("__sso_string_base::_M_create"));
317 
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  {
323  __capacity = 2 * __old_capacity;
324  // Never allocate a string bigger than max_size.
325  if (__capacity > _M_max_size())
326  __capacity = _M_max_size();
327  }
328 
329  // NB: Need an array of char_type[__capacity], plus a terminating
330  // null char_type() element.
331  return _M_get_allocator().allocate(__capacity + 1);
332  }
333 
334  template<typename _CharT, typename _Traits, typename _Alloc>
335  __sso_string_base<_CharT, _Traits, _Alloc>::
336  __sso_string_base(const _Alloc& __a)
337  : _M_dataplus(__a, _M_local_data)
338  { _M_set_length(0); }
339 
340  template<typename _CharT, typename _Traits, typename _Alloc>
341  __sso_string_base<_CharT, _Traits, _Alloc>::
342  __sso_string_base(const __sso_string_base& __rcs)
343  : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
344  { _M_construct(__rcs._M_data(), __rcs._M_data() + __rcs._M_length()); }
345 
346 #if __cplusplus >= 201103L
347  template<typename _CharT, typename _Traits, typename _Alloc>
348  __sso_string_base<_CharT, _Traits, _Alloc>::
349  __sso_string_base(__sso_string_base&& __rcs)
350  : _M_dataplus(__rcs._M_get_allocator(), _M_local_data)
351  {
352  if (__rcs._M_is_local())
353  {
354  if (__rcs._M_length())
355  traits_type::copy(_M_local_data, __rcs._M_local_data,
356  _S_local_capacity + 1);
357  }
358  else
359  {
360  _M_data(__rcs._M_data());
361  _M_capacity(__rcs._M_allocated_capacity);
362  }
363 
364  _M_set_length(__rcs._M_length());
365  __rcs._M_data(__rcs._M_local_data);
366  __rcs._M_set_length(0);
367  }
368 #endif
369 
370  template<typename _CharT, typename _Traits, typename _Alloc>
371  __sso_string_base<_CharT, _Traits, _Alloc>::
372  __sso_string_base(size_type __n, _CharT __c, const _Alloc& __a)
373  : _M_dataplus(__a, _M_local_data)
374  { _M_construct(__n, __c); }
375 
376  template<typename _CharT, typename _Traits, typename _Alloc>
377  template<typename _InputIterator>
378  __sso_string_base<_CharT, _Traits, _Alloc>::
379  __sso_string_base(_InputIterator __beg, _InputIterator __end,
380  const _Alloc& __a)
381  : _M_dataplus(__a, _M_local_data)
382  { _M_construct(__beg, __end); }
383 
384  // NB: This is the special case for Input Iterators, used in
385  // istreambuf_iterators, etc.
386  // Input Iterators have a cost structure very different from
387  // pointers, calling for a different coding style.
388  template<typename _CharT, typename _Traits, typename _Alloc>
389  template<typename _InIterator>
390  void
391  __sso_string_base<_CharT, _Traits, _Alloc>::
392  _M_construct(_InIterator __beg, _InIterator __end,
394  {
395  size_type __len = 0;
396  size_type __capacity = size_type(_S_local_capacity);
397 
398  while (__beg != __end && __len < __capacity)
399  {
400  _M_data()[__len++] = *__beg;
401  ++__beg;
402  }
403 
404  __try
405  {
406  while (__beg != __end)
407  {
408  if (__len == __capacity)
409  {
410  // Allocate more space.
411  __capacity = __len + 1;
412  _CharT* __another = _M_create(__capacity, __len);
413  this->_S_copy(__another, _M_data(), __len);
414  _M_dispose();
415  _M_data(__another);
416  _M_capacity(__capacity);
417  }
418  _M_data()[__len++] = *__beg;
419  ++__beg;
420  }
421  }
422  __catch(...)
423  {
424  _M_dispose();
425  __throw_exception_again;
426  }
427 
428  _M_set_length(__len);
429  }
430 
431  template<typename _CharT, typename _Traits, typename _Alloc>
432  template<typename _InIterator>
433  void
434  __sso_string_base<_CharT, _Traits, _Alloc>::
435  _M_construct(_InIterator __beg, _InIterator __end,
437  {
438  // NB: Not required, but considered best practice.
439  if (__is_null_pointer(__beg) && __beg != __end)
440  std::__throw_logic_error(__N("__sso_string_base::"
441  "_M_construct null not valid"));
442 
443  size_type __dnew = static_cast<size_type>(std::distance(__beg, __end));
444 
445  if (__dnew > size_type(_S_local_capacity))
446  {
447  _M_data(_M_create(__dnew, size_type(0)));
448  _M_capacity(__dnew);
449  }
450 
451  // Check for out_of_range and length_error exceptions.
452  __try
453  { this->_S_copy_chars(_M_data(), __beg, __end); }
454  __catch(...)
455  {
456  _M_dispose();
457  __throw_exception_again;
458  }
459 
460  _M_set_length(__dnew);
461  }
462 
463  template<typename _CharT, typename _Traits, typename _Alloc>
464  void
465  __sso_string_base<_CharT, _Traits, _Alloc>::
466  _M_construct(size_type __n, _CharT __c)
467  {
468  if (__n > size_type(_S_local_capacity))
469  {
470  _M_data(_M_create(__n, size_type(0)));
471  _M_capacity(__n);
472  }
473 
474  if (__n)
475  this->_S_assign(_M_data(), __n, __c);
476 
477  _M_set_length(__n);
478  }
479 
480  template<typename _CharT, typename _Traits, typename _Alloc>
481  void
482  __sso_string_base<_CharT, _Traits, _Alloc>::
483  _M_assign(const __sso_string_base& __rcs)
484  {
485  if (this != &__rcs)
486  {
487  const size_type __rsize = __rcs._M_length();
488  const size_type __capacity = _M_capacity();
489 
490  if (__rsize > __capacity)
491  {
492  size_type __new_capacity = __rsize;
493  _CharT* __tmp = _M_create(__new_capacity, __capacity);
494  _M_dispose();
495  _M_data(__tmp);
496  _M_capacity(__new_capacity);
497  }
498 
499  if (__rsize)
500  this->_S_copy(_M_data(), __rcs._M_data(), __rsize);
501 
502  _M_set_length(__rsize);
503  }
504  }
505 
506  template<typename _CharT, typename _Traits, typename _Alloc>
507  void
508  __sso_string_base<_CharT, _Traits, _Alloc>::
509  _M_reserve(size_type __res)
510  {
511  // Make sure we don't shrink below the current size.
512  if (__res < _M_length())
513  __res = _M_length();
514 
515  const size_type __capacity = _M_capacity();
516  if (__res != __capacity)
517  {
518  if (__res > __capacity
519  || __res > size_type(_S_local_capacity))
520  {
521  _CharT* __tmp = _M_create(__res, __capacity);
522  this->_S_copy(__tmp, _M_data(), _M_length() + 1);
523  _M_dispose();
524  _M_data(__tmp);
525  _M_capacity(__res);
526  }
527  else if (!_M_is_local())
528  {
529  this->_S_copy(_M_local_data, _M_data(), _M_length() + 1);
530  _M_destroy(__capacity);
531  _M_data(_M_local_data);
532  }
533  }
534  }
535 
536  template<typename _CharT, typename _Traits, typename _Alloc>
537  void
538  __sso_string_base<_CharT, _Traits, _Alloc>::
539  _M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
540  size_type __len2)
541  {
542  const size_type __how_much = _M_length() - __pos - __len1;
543 
544  size_type __new_capacity = _M_length() + __len2 - __len1;
545  _CharT* __r = _M_create(__new_capacity, _M_capacity());
546 
547  if (__pos)
548  this->_S_copy(__r, _M_data(), __pos);
549  if (__s && __len2)
550  this->_S_copy(__r + __pos, __s, __len2);
551  if (__how_much)
552  this->_S_copy(__r + __pos + __len2,
553  _M_data() + __pos + __len1, __how_much);
554 
555  _M_dispose();
556  _M_data(__r);
557  _M_capacity(__new_capacity);
558  }
559 
560  template<typename _CharT, typename _Traits, typename _Alloc>
561  void
562  __sso_string_base<_CharT, _Traits, _Alloc>::
563  _M_erase(size_type __pos, size_type __n)
564  {
565  const size_type __how_much = _M_length() - __pos - __n;
566 
567  if (__how_much && __n)
568  this->_S_move(_M_data() + __pos, _M_data() + __pos + __n, __how_much);
569 
570  _M_set_length(_M_length() - __n);
571  }
572 
573 _GLIBCXX_END_NAMESPACE_VERSION
574 } // namespace
575 
576 #endif /* _SSO_STRING_BASE_H */
GNU extensions for public use.
Forward iterators support a superset of input iterator operations.
Marking input iterators.
iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.