libstdc++: sstream.tcc Source File

libstdc++

sstream.tcc
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1// String based streams -*- C++ -*-
2
3// Copyright (C) 1997-2026 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#ifdef _GLIBCXX_SYSHDR
38#pragma GCC system_header
39#endif
40#pragma GCC diagnostic push
41#pragma GCC diagnostic ignored "-Wc++11-extensions" // extern template
42
43namespace std _GLIBCXX_VISIBILITY(default)
44{
45_GLIBCXX_BEGIN_NAMESPACE_VERSION
46
47 template <class _CharT, class _Traits, class _Alloc>
48 typename basic_stringbuf<_CharT, _Traits, _Alloc>::int_type
49 basic_stringbuf<_CharT, _Traits, _Alloc>::
50 pbackfail(int_type __c)
51 {
52 int_type __ret = traits_type::eof();
53 if (this->eback() < this->gptr())
54 {
55 // Try to put back __c into input sequence in one of three ways.
56 // Order these tests done in is unspecified by the standard.
57 const bool __testeof = traits_type::eq_int_type(__c, __ret);
58 if (!__testeof)
59 {
60 const bool __testeq = traits_type::eq(traits_type::
61 to_char_type(__c),
62 this->gptr()[-1]);
63 const bool __testout = this->_M_mode & ios_base::out;
64 if (__testeq || __testout)
65 {
66 this->gbump(-1);
67 if (!__testeq)
68 *this->gptr() = traits_type::to_char_type(__c);
69 __ret = __c;
70 }
71 }
72 else
73 {
74 this->gbump(-1);
75 __ret = traits_type::not_eof(__c);
76 }
77 }
78 return __ret;
79 }
80
81 template <class _CharT, class _Traits, class _Alloc>
82 typename basic_stringbuf<_CharT, _Traits, _Alloc>::int_type
83 basic_stringbuf<_CharT, _Traits, _Alloc>::
84 overflow(int_type __c)
85 {
86 const bool __testout = this->_M_mode & ios_base::out;
87 if (__builtin_expect(!__testout, false))
88 return traits_type::eof();
89
90 const bool __testeof = traits_type::eq_int_type(__c, traits_type::eof());
91 if (__builtin_expect(__testeof, false))
92 return traits_type::not_eof(__c);
93
94 const __size_type __capacity = _M_string.capacity();
95
96#if _GLIBCXX_USE_CXX11_ABI
97 if (size_t(this->epptr() - this->pbase()) < __capacity)
98 {
99 // There is additional capacity in _M_string that can be used.
100 char_type* __base = const_cast<char_type*>(_M_string.data());
101 _M_pbump(__base, __base + __capacity, this->pptr() - this->pbase());
102 if (_M_mode & ios_base::in)
103 {
104 const __size_type __nget = this->gptr() - this->eback();
105 const __size_type __eget = this->egptr() - this->eback();
106 this->setg(__base, __base + __nget, __base + __eget + 1);
107 }
108 *this->pptr() = traits_type::to_char_type(__c);
109 this->pbump(1);
110 return __c;
111 }
112#endif
113
114 const __size_type __max_size = _M_string.max_size();
115 const bool __testput = this->pptr() < this->epptr();
116 if (__builtin_expect(!__testput && __capacity == __max_size, false))
117 return traits_type::eof();
118
119 // Try to append __c into output sequence in one of two ways.
120 // Order these tests done in is unspecified by the standard.
121 const char_type __conv = traits_type::to_char_type(__c);
122 if (!__testput)
123 {
124 // NB: Start ostringstream buffers at 512 chars. This is an
125 // experimental value (pronounced "arbitrary" in some of the
126 // hipper English-speaking countries), and can be changed to
127 // suit particular needs.
128 //
129 // _GLIBCXX_RESOLVE_LIB_DEFECTS
130 // 169. Bad efficiency of overflow() mandated
131 // 432. stringbuf::overflow() makes only one write position
132 // available
133 const __size_type __opt_len = std::max(__size_type(2 * __capacity),
134 __size_type(512));
135 const __size_type __len = std::min(__opt_len, __max_size);
136 __string_type __tmp(_M_string.get_allocator());
137 __tmp.reserve(__len);
138 if (this->pbase())
139 __tmp.assign(this->pbase(), this->epptr() - this->pbase());
140 __tmp.push_back(__conv);
141 _M_string.swap(__tmp);
142 _M_sync(const_cast<char_type*>(_M_string.data()),
143 this->gptr() - this->eback(), this->pptr() - this->pbase());
144 }
145 else
146 *this->pptr() = __conv;
147 this->pbump(1);
148 return __c;
149 }
150
151 template <class _CharT, class _Traits, class _Alloc>
152 typename basic_stringbuf<_CharT, _Traits, _Alloc>::int_type
153 basic_stringbuf<_CharT, _Traits, _Alloc>::
154 underflow()
155 {
156 int_type __ret = traits_type::eof();
157 const bool __testin = this->_M_mode & ios_base::in;
158 if (__testin)
159 {
160 // Update egptr() to match the actual string end.
161 _M_update_egptr();
162
163 if (this->gptr() < this->egptr())
164 __ret = traits_type::to_int_type(*this->gptr());
165 }
166 return __ret;
167 }
168
169 template <class _CharT, class _Traits, class _Alloc>
170 typename basic_stringbuf<_CharT, _Traits, _Alloc>::pos_type
171 basic_stringbuf<_CharT, _Traits, _Alloc>::
172 seekoff(off_type __off, ios_base::seekdir __way, ios_base::openmode __mode)
173 {
174 pos_type __ret = pos_type(off_type(-1));
175 bool __testin = (ios_base::in & this->_M_mode & __mode) != 0;
176 bool __testout = (ios_base::out & this->_M_mode & __mode) != 0;
177 const bool __testboth = __testin && __testout && __way != ios_base::cur;
178 __testin &= !(__mode & ios_base::out);
179 __testout &= !(__mode & ios_base::in);
180
181 // _GLIBCXX_RESOLVE_LIB_DEFECTS
182 // 453. basic_stringbuf::seekoff need not always fail for an empty stream.
183 const char_type* __beg = __testin ? this->eback() : this->pbase();
184 if ((__beg || !__off) && (__testin || __testout || __testboth))
185 {
186 _M_update_egptr();
187
188 off_type __newoffi = __off;
189 off_type __newoffo = __newoffi;
190 if (__way == ios_base::cur)
191 {
192 __newoffi += this->gptr() - __beg;
193 __newoffo += this->pptr() - __beg;
194 }
195 else if (__way == ios_base::end)
196 __newoffo = __newoffi += this->egptr() - __beg;
197
198 if ((__testin || __testboth)
199 && __newoffi >= 0
200 && this->egptr() - __beg >= __newoffi)
201 {
202 this->setg(this->eback(), this->eback() + __newoffi,
203 this->egptr());
204 __ret = pos_type(__newoffi);
205 }
206 if ((__testout || __testboth)
207 && __newoffo >= 0
208 && this->egptr() - __beg >= __newoffo)
209 {
210 _M_pbump(this->pbase(), this->epptr(), __newoffo);
211 __ret = pos_type(__newoffo);
212 }
213 }
214 return __ret;
215 }
216
217 template <class _CharT, class _Traits, class _Alloc>
218 typename basic_stringbuf<_CharT, _Traits, _Alloc>::pos_type
219 basic_stringbuf<_CharT, _Traits, _Alloc>::
220 seekpos(pos_type __sp, ios_base::openmode __mode)
221 {
222 pos_type __ret = pos_type(off_type(-1));
223 const bool __testin = (ios_base::in & this->_M_mode & __mode) != 0;
224 const bool __testout = (ios_base::out & this->_M_mode & __mode) != 0;
225
226 const char_type* __beg = __testin ? this->eback() : this->pbase();
227 if ((__beg || !off_type(__sp)) && (__testin || __testout))
228 {
229 _M_update_egptr();
230
231 const off_type __pos(__sp);
232 const bool __testpos = (0 <= __pos
233 && __pos <= this->egptr() - __beg);
234 if (__testpos)
235 {
236 if (__testin)
237 this->setg(this->eback(), this->eback() + __pos,
238 this->egptr());
239 if (__testout)
240 _M_pbump(this->pbase(), this->epptr(), __pos);
241 __ret = __sp;
242 }
243 }
244 return __ret;
245 }
246
247 template <class _CharT, class _Traits, class _Alloc>
248 void
249 basic_stringbuf<_CharT, _Traits, _Alloc>::
250 _M_sync(char_type* __base, __size_type __i, __size_type __o)
251 {
252 const bool __testin = _M_mode & ios_base::in;
253 const bool __testout = _M_mode & ios_base::out;
254 char_type* __endg = __base + _M_string.size();
255 char_type* __endp = __base + _M_string.capacity();
256
257 if (__base != _M_string.data())
258 {
259 // setbuf: __i == size of buffer area (_M_string.size() == 0).
260 __endg += __i;
261 __i = 0;
262 __endp = __endg;
263 }
264
265 if (__testin)
266 this->setg(__base, __base + __i, __endg);
267 if (__testout)
268 {
269 _M_pbump(__base, __endp, __o);
270 // egptr() always tracks the string end. When !__testin,
271 // for the correct functioning of the streambuf inlines
272 // the other get area pointers are identical.
273 if (!__testin)
274 this->setg(__endg, __endg, __endg);
275 }
276 }
277
278 template <class _CharT, class _Traits, class _Alloc>
279 void
280 basic_stringbuf<_CharT, _Traits, _Alloc>::
281 _M_pbump(char_type* __pbeg, char_type* __pend, off_type __off)
282 {
283 this->setp(__pbeg, __pend);
284 while (__off > __gnu_cxx::__numeric_traits<int>::__max)
285 {
286 this->pbump(__gnu_cxx::__numeric_traits<int>::__max);
287 __off -= __gnu_cxx::__numeric_traits<int>::__max;
288 }
289 this->pbump(__off);
290 }
291
292 // Inhibit implicit instantiations for required instantiations,
293 // which are defined via explicit instantiations elsewhere.
294#if _GLIBCXX_EXTERN_TEMPLATE
295 extern template class basic_stringbuf<char>;
296 extern template class basic_istringstream<char>;
297 extern template class basic_ostringstream<char>;
298 extern template class basic_stringstream<char>;
299
300#ifdef _GLIBCXX_USE_WCHAR_T
301 extern template class basic_stringbuf<wchar_t>;
302 extern template class basic_istringstream<wchar_t>;
303 extern template class basic_ostringstream<wchar_t>;
304 extern template class basic_stringstream<wchar_t>;
305#endif
306#endif
307
308_GLIBCXX_END_NAMESPACE_VERSION
309} // namespace std
310
311#pragma GCC diagnostic pop
312#endif
std::max
constexpr const _Tp & max(const _Tp &, const _Tp &)
This does what you think it does.
Definition stl_algobase.h:256
std::min
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition stl_algobase.h:232
std
ISO C++ entities toplevel namespace is std.
std::basic_streambuf::epptr
char_type * epptr() const
Access to the put area.
Definition streambuf:549
std::basic_streambuf::pptr
char_type * pptr() const
Access to the put area.
Definition streambuf:546
std::basic_streambuf::setg
void setg(char_type *__gbeg, char_type *__gnext, char_type *__gend)
Setting the three read area pointers.
Definition streambuf:523
std::basic_streambuf::eback
char_type * eback() const
Access to the get area.
Definition streambuf:491
std::basic_streambuf::egptr
char_type * egptr() const
Access to the get area.
Definition streambuf:501
std::basic_streambuf::gptr
char_type * gptr() const
Access to the get area.
Definition streambuf:498
std::basic_streambuf::gbump
void gbump(int __n)
Moving the read position.
Definition streambuf:511
std::basic_streambuf::pbump
void pbump(int __n)
Moving the write position.
Definition streambuf:559
std::basic_streambuf::pbase
char_type * pbase() const
Access to the put area.
Definition streambuf:543
std::basic_stringbuf
The actual work of input and output (for std::string).
Definition sstream:88
std::basic_stringbuf::underflow
virtual int_type underflow()
Fetches more data from the controlled sequence.
Definition sstream.tcc:154
std::basic_stringbuf::seekpos
virtual pos_type seekpos(pos_type __sp, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream positions.
Definition sstream.tcc:220
std::basic_stringbuf::seekoff
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:172
std::basic_stringbuf::overflow
virtual int_type overflow(int_type __c=traits_type::eof())
Consumes data from the buffer; writes to the controlled sequence.
Definition sstream.tcc:84
std::basic_stringbuf::pbackfail
virtual int_type pbackfail(int_type __c=traits_type::eof())
Tries to back up the input sequence.
Definition sstream.tcc:50
std::basic_stringbuf::_M_mode
ios_base::openmode _M_mode
Place to stash in || out || in | out settings for current stringbuf.
Definition sstream:114
std::basic_istringstream
Controlling input for std::string.
Definition sstream:609
std::basic_ostringstream
Controlling output for std::string.
Definition sstream:875
std::basic_stringstream
Controlling input and output for std::string.
Definition sstream:1141
std::basic_string::reserve
constexpr void reserve(size_type __res_arg)
Attempt to preallocate enough memory for specified number of characters.
Definition cow_string.h:3669
std::basic_string::assign
constexpr basic_string & assign(const basic_string &__str)
Set value to contents of another string.
Definition basic_string.h:1764
std::basic_string::push_back
constexpr void push_back(_CharT __c)
Append a single character.
Definition basic_string.h:1748
std::off_type
std::ios_base::cur
static const seekdir cur
Request a seek relative to the current position within the sequence.
Definition ios_base.h:529
std::ios_base::end
static const seekdir end
Request a seek relative to the current end of the sequence.
Definition ios_base.h:532
std::ios_base::in
static const openmode in
Open for input. Default for ifstream and fstream.
Definition ios_base.h:498
std::ios_base::out
static const openmode out
Open for output. Default for ofstream and fstream.
Definition ios_base.h:501
std::ios_base::openmode
_Ios_Openmode openmode
This is a bitmask type.
Definition ios_base.h:484
std::ios_base::seekdir
_Ios_Seekdir seekdir
This is an enumerated type.
Definition ios_base.h:523