libstdc++
sstream.tcc
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1 // String based streams -*- C++ -*-
2 
3 // Copyright (C) 1997-2021 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 bits/sstream.tcc
26  * This is an internal header file, included by other library headers.
27  * Do not attempt to use it directly. @headername{sstream}
28  */
29 
30 //
31 // ISO C++ 14882: 27.7 String-based streams
32 //
33 
34 #ifndef _SSTREAM_TCC
35 #define _SSTREAM_TCC 1
36 
37 #pragma GCC system_header
38 
39 namespace std _GLIBCXX_VISIBILITY(default)
40 {
41 _GLIBCXX_BEGIN_NAMESPACE_VERSION
42 
43  template <class _CharT, class _Traits, class _Alloc>
44  typename basic_stringbuf<_CharT, _Traits, _Alloc>::int_type
46  pbackfail(int_type __c)
47  {
48  int_type __ret = traits_type::eof();
49  if (this->eback() < this->gptr())
50  {
51  // Try to put back __c into input sequence in one of three ways.
52  // Order these tests done in is unspecified by the standard.
53  const bool __testeof = traits_type::eq_int_type(__c, __ret);
54  if (!__testeof)
55  {
56  const bool __testeq = traits_type::eq(traits_type::
57  to_char_type(__c),
58  this->gptr()[-1]);
59  const bool __testout = this->_M_mode & ios_base::out;
60  if (__testeq || __testout)
61  {
62  this->gbump(-1);
63  if (!__testeq)
64  *this->gptr() = traits_type::to_char_type(__c);
65  __ret = __c;
66  }
67  }
68  else
69  {
70  this->gbump(-1);
71  __ret = traits_type::not_eof(__c);
72  }
73  }
74  return __ret;
75  }
76 
77  template <class _CharT, class _Traits, class _Alloc>
78  typename basic_stringbuf<_CharT, _Traits, _Alloc>::int_type
80  overflow(int_type __c)
81  {
82  const bool __testout = this->_M_mode & ios_base::out;
83  if (__builtin_expect(!__testout, false))
84  return traits_type::eof();
85 
86  const bool __testeof = traits_type::eq_int_type(__c, traits_type::eof());
87  if (__builtin_expect(__testeof, false))
88  return traits_type::not_eof(__c);
89 
90  const __size_type __capacity = _M_string.capacity();
91 
92 #if _GLIBCXX_USE_CXX11_ABI
93  if (size_t(this->epptr() - this->pbase()) < __capacity)
94  {
95  // There is additional capacity in _M_string that can be used.
96  char_type* __base = const_cast<char_type*>(_M_string.data());
97  _M_pbump(__base, __base + __capacity, this->pptr() - this->pbase());
98  if (_M_mode & ios_base::in)
99  {
100  const __size_type __nget = this->gptr() - this->eback();
101  const __size_type __eget = this->egptr() - this->eback();
102  this->setg(__base, __base + __nget, __base + __eget + 1);
103  }
104  *this->pptr() = traits_type::to_char_type(__c);
105  this->pbump(1);
106  return __c;
107  }
108 #endif
109 
110  const __size_type __max_size = _M_string.max_size();
111  const bool __testput = this->pptr() < this->epptr();
112  if (__builtin_expect(!__testput && __capacity == __max_size, false))
113  return traits_type::eof();
114 
115  // Try to append __c into output sequence in one of two ways.
116  // Order these tests done in is unspecified by the standard.
117  const char_type __conv = traits_type::to_char_type(__c);
118  if (!__testput)
119  {
120  // NB: Start ostringstream buffers at 512 chars. This is an
121  // experimental value (pronounced "arbitrary" in some of the
122  // hipper English-speaking countries), and can be changed to
123  // suit particular needs.
124  //
125  // _GLIBCXX_RESOLVE_LIB_DEFECTS
126  // 169. Bad efficiency of overflow() mandated
127  // 432. stringbuf::overflow() makes only one write position
128  // available
129  const __size_type __opt_len = std::max(__size_type(2 * __capacity),
130  __size_type(512));
131  const __size_type __len = std::min(__opt_len, __max_size);
132  __string_type __tmp(_M_string.get_allocator());
133  __tmp.reserve(__len);
134  if (this->pbase())
135  __tmp.assign(this->pbase(), this->epptr() - this->pbase());
136  __tmp.push_back(__conv);
137  _M_string.swap(__tmp);
138  _M_sync(const_cast<char_type*>(_M_string.data()),
139  this->gptr() - this->eback(), this->pptr() - this->pbase());
140  }
141  else
142  *this->pptr() = __conv;
143  this->pbump(1);
144  return __c;
145  }
146 
147  template <class _CharT, class _Traits, class _Alloc>
148  typename basic_stringbuf<_CharT, _Traits, _Alloc>::int_type
150  underflow()
151  {
152  int_type __ret = traits_type::eof();
153  const bool __testin = this->_M_mode & ios_base::in;
154  if (__testin)
155  {
156  // Update egptr() to match the actual string end.
157  _M_update_egptr();
158 
159  if (this->gptr() < this->egptr())
160  __ret = traits_type::to_int_type(*this->gptr());
161  }
162  return __ret;
163  }
164 
165  template <class _CharT, class _Traits, class _Alloc>
166  typename basic_stringbuf<_CharT, _Traits, _Alloc>::pos_type
168  seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode __mode)
169  {
170  pos_type __ret = pos_type(off_type(-1));
171  bool __testin = (ios_base::in & this->_M_mode & __mode) != 0;
172  bool __testout = (ios_base::out & this->_M_mode & __mode) != 0;
173  const bool __testboth = __testin && __testout && __way != ios_base::cur;
174  __testin &= !(__mode & ios_base::out);
175  __testout &= !(__mode & ios_base::in);
176 
177  // _GLIBCXX_RESOLVE_LIB_DEFECTS
178  // 453. basic_stringbuf::seekoff need not always fail for an empty stream.
179  const char_type* __beg = __testin ? this->eback() : this->pbase();
180  if ((__beg || !__off) && (__testin || __testout || __testboth))
181  {
182  _M_update_egptr();
183 
184  off_type __newoffi = __off;
185  off_type __newoffo = __newoffi;
186  if (__way == ios_base::cur)
187  {
188  __newoffi += this->gptr() - __beg;
189  __newoffo += this->pptr() - __beg;
190  }
191  else if (__way == ios_base::end)
192  __newoffo = __newoffi += this->egptr() - __beg;
193 
194  if ((__testin || __testboth)
195  && __newoffi >= 0
196  && this->egptr() - __beg >= __newoffi)
197  {
198  this->setg(this->eback(), this->eback() + __newoffi,
199  this->egptr());
200  __ret = pos_type(__newoffi);
201  }
202  if ((__testout || __testboth)
203  && __newoffo >= 0
204  && this->egptr() - __beg >= __newoffo)
205  {
206  _M_pbump(this->pbase(), this->epptr(), __newoffo);
207  __ret = pos_type(__newoffo);
208  }
209  }
210  return __ret;
211  }
212 
213  template <class _CharT, class _Traits, class _Alloc>
214  typename basic_stringbuf<_CharT, _Traits, _Alloc>::pos_type
216  seekpos(pos_type __sp, ios_base::openmode __mode)
217  {
218  pos_type __ret = pos_type(off_type(-1));
219  const bool __testin = (ios_base::in & this->_M_mode & __mode) != 0;
220  const bool __testout = (ios_base::out & this->_M_mode & __mode) != 0;
221 
222  const char_type* __beg = __testin ? this->eback() : this->pbase();
223  if ((__beg || !off_type(__sp)) && (__testin || __testout))
224  {
225  _M_update_egptr();
226 
227  const off_type __pos(__sp);
228  const bool __testpos = (0 <= __pos
229  && __pos <= this->egptr() - __beg);
230  if (__testpos)
231  {
232  if (__testin)
233  this->setg(this->eback(), this->eback() + __pos,
234  this->egptr());
235  if (__testout)
236  _M_pbump(this->pbase(), this->epptr(), __pos);
237  __ret = __sp;
238  }
239  }
240  return __ret;
241  }
242 
243  template <class _CharT, class _Traits, class _Alloc>
244  void
246  _M_sync(char_type* __base, __size_type __i, __size_type __o)
247  {
248  const bool __testin = _M_mode & ios_base::in;
249  const bool __testout = _M_mode & ios_base::out;
250  char_type* __endg = __base + _M_string.size();
251  char_type* __endp = __base + _M_string.capacity();
252 
253  if (__base != _M_string.data())
254  {
255  // setbuf: __i == size of buffer area (_M_string.size() == 0).
256  __endg += __i;
257  __i = 0;
258  __endp = __endg;
259  }
260 
261  if (__testin)
262  this->setg(__base, __base + __i, __endg);
263  if (__testout)
264  {
265  _M_pbump(__base, __endp, __o);
266  // egptr() always tracks the string end. When !__testin,
267  // for the correct functioning of the streambuf inlines
268  // the other get area pointers are identical.
269  if (!__testin)
270  this->setg(__endg, __endg, __endg);
271  }
272  }
273 
274  template <class _CharT, class _Traits, class _Alloc>
275  void
276  basic_stringbuf<_CharT, _Traits, _Alloc>::
277  _M_pbump(char_type* __pbeg, char_type* __pend, off_type __off)
278  {
279  this->setp(__pbeg, __pend);
280  while (__off > __gnu_cxx::__numeric_traits<int>::__max)
281  {
282  this->pbump(__gnu_cxx::__numeric_traits<int>::__max);
283  __off -= __gnu_cxx::__numeric_traits<int>::__max;
284  }
285  this->pbump(__off);
286  }
287 
288  // Inhibit implicit instantiations for required instantiations,
289  // which are defined via explicit instantiations elsewhere.
290 #if _GLIBCXX_EXTERN_TEMPLATE
291  extern template class basic_stringbuf<char>;
292  extern template class basic_istringstream<char>;
293  extern template class basic_ostringstream<char>;
294  extern template class basic_stringstream<char>;
295 
296 #ifdef _GLIBCXX_USE_WCHAR_T
297  extern template class basic_stringbuf<wchar_t>;
298  extern template class basic_istringstream<wchar_t>;
299  extern template class basic_ostringstream<wchar_t>;
300  extern template class basic_stringstream<wchar_t>;
301 #endif
302 #endif
303 
304 _GLIBCXX_END_NAMESPACE_VERSION
305 } // namespace std
306 
307 #endif
constexpr const _Tp & max(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:254
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition: stl_algobase.h:230
ISO C++ entities toplevel namespace is std.
constexpr _Iterator __base(_Iterator __it)
The actual work of input and output (for std::string).
Definition: sstream:73
virtual int_type underflow()
Fetches more data from the controlled sequence.
Definition: sstream.tcc:150
virtual pos_type seekpos(pos_type __sp, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream positions.
Definition: sstream.tcc:216
virtual pos_type seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream positions.
Definition: sstream.tcc:168
virtual int_type overflow(int_type __c=traits_type::eof())
Consumes data from the buffer; writes to the controlled sequence.
Definition: sstream.tcc:80
virtual int_type pbackfail(int_type __c=traits_type::eof())
Tries to back up the input sequence.
Definition: sstream.tcc:46
void push_back(_CharT __c)
Append a single character.
void reserve(size_type __res_arg)
Attempt to preallocate enough memory for specified number of characters.
basic_string & assign(const basic_string &__str)
Set value to contents of another string.
static const seekdir cur
Request a seek relative to the current position within the sequence.
Definition: ios_base.h:485
static const seekdir end
Request a seek relative to the current end of the sequence.
Definition: ios_base.h:488
static const openmode in
Open for input. Default for ifstream and fstream.
Definition: ios_base.h:461
static const openmode out
Open for output. Default for ofstream and fstream.
Definition: ios_base.h:464