libstdc++
sstream
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1 // String based streams -*- C++ -*-
2 
3 // Copyright (C) 1997-2025 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 include/sstream
26  * This is a Standard C++ Library header.
27  */
28 
29 //
30 // ISO C++ 14882: 27.7 String-based streams
31 //
32 
33 #ifndef _GLIBCXX_SSTREAM
34 #define _GLIBCXX_SSTREAM 1
35 
36 #ifdef _GLIBCXX_SYSHDR
37 #pragma GCC system_header
38 #endif
39 
40 #include <bits/requires_hosted.h> // iostream
41 
42 #include <istream>
43 #include <ostream>
44 #include <bits/alloc_traits.h> // allocator_traits, __allocator_like
45 
46 #if __cplusplus > 201703L && _GLIBCXX_USE_CXX11_ABI
47 # define _GLIBCXX_LVAL_REF_QUAL &
48 # define _GLIBCXX_SSTREAM_ALWAYS_INLINE
49 #else
50 # define _GLIBCXX_LVAL_REF_QUAL
51 // For symbols that are not exported from libstdc++.so for the COW string ABI.
52 # define _GLIBCXX_SSTREAM_ALWAYS_INLINE [[__gnu__::__always_inline__]]
53 #endif
54 
55 
56 
57 namespace std _GLIBCXX_VISIBILITY(default)
58 {
59 _GLIBCXX_BEGIN_NAMESPACE_VERSION
60 _GLIBCXX_BEGIN_NAMESPACE_CXX11
61 
62  // [27.7.1] template class basic_stringbuf
63  /**
64  * @brief The actual work of input and output (for std::string).
65  * @ingroup io
66  *
67  * @tparam _CharT Type of character stream.
68  * @tparam _Traits Traits for character type, defaults to
69  * char_traits<_CharT>.
70  * @tparam _Alloc Allocator type, defaults to allocator<_CharT>.
71  *
72  * This class associates either or both of its input and output sequences
73  * with a sequence of characters, which can be initialized from, or made
74  * available as, a @c std::basic_string. (Paraphrased from [27.7.1]/1.)
75  *
76  * For this class, open modes (of type @c ios_base::openmode) have
77  * @c in set if the input sequence can be read, and @c out set if the
78  * output sequence can be written.
79  */
80  template<typename _CharT, typename _Traits, typename _Alloc>
81  class basic_stringbuf : public basic_streambuf<_CharT, _Traits>
82  {
83  struct __xfer_bufptrs;
84 
85 #if __cplusplus >= 201103L
86  using allocator_traits = std::allocator_traits<_Alloc>;
87  using _Noexcept_swap
88  = __or_<typename allocator_traits::propagate_on_container_swap,
89  typename allocator_traits::is_always_equal>;
90 #endif
91 
92  public:
93  // Types:
94  typedef _CharT char_type;
95  typedef _Traits traits_type;
96  // _GLIBCXX_RESOLVE_LIB_DEFECTS
97  // 251. basic_stringbuf missing allocator_type
98  typedef _Alloc allocator_type;
99  typedef typename traits_type::int_type int_type;
100  typedef typename traits_type::pos_type pos_type;
101  typedef typename traits_type::off_type off_type;
102 
103  typedef basic_streambuf<char_type, traits_type> __streambuf_type;
104  typedef basic_string<char_type, _Traits, _Alloc> __string_type;
105  typedef typename __string_type::size_type __size_type;
106 
107  protected:
108  /// Place to stash in || out || in | out settings for current stringbuf.
109  ios_base::openmode _M_mode;
110 
111  // Data Members:
112  __string_type _M_string;
113 
114  public:
115  // Constructors:
116 
117  /**
118  * @brief Starts with an empty string buffer.
119  *
120  * The default constructor initializes the parent class using its
121  * own default ctor.
122  */
123  basic_stringbuf()
124  : __streambuf_type(), _M_mode(ios_base::in | ios_base::out), _M_string()
125  { }
126 
127  /**
128  * @brief Starts with an empty string buffer.
129  * @param __mode Whether the buffer can read, or write, or both.
130  *
131  * The default constructor initializes the parent class using its
132  * own default ctor.
133  */
134  explicit
135  basic_stringbuf(ios_base::openmode __mode)
136  : __streambuf_type(), _M_mode(__mode), _M_string()
137  { }
138 
139  /**
140  * @brief Starts with an existing string buffer.
141  * @param __str A string to copy as a starting buffer.
142  * @param __mode Whether the buffer can read, or write, or both.
143  *
144  * This constructor initializes the parent class using its
145  * own default ctor.
146  */
147  explicit
148  basic_stringbuf(const __string_type& __str,
149  ios_base::openmode __mode = ios_base::in | ios_base::out)
150  : __streambuf_type(), _M_mode(),
151  _M_string(__str.data(), __str.size(), __str.get_allocator())
152  { _M_stringbuf_init(__mode); }
153 
154 #if __cplusplus >= 201103L
155  basic_stringbuf(const basic_stringbuf&) = delete;
156 
157  basic_stringbuf(basic_stringbuf&& __rhs)
158  : basic_stringbuf(std::move(__rhs), __xfer_bufptrs(__rhs, this))
159  { __rhs._M_sync(const_cast<char_type*>(__rhs._M_string.data()), 0, 0); }
160 
161 #if __cplusplus > 201703L && _GLIBCXX_USE_CXX11_ABI
162  explicit
163  basic_stringbuf(const allocator_type& __a)
164  : basic_stringbuf(ios_base::in | std::ios_base::out, __a)
165  { }
166 
167  basic_stringbuf(ios_base::openmode __mode,
168  const allocator_type& __a)
169  : __streambuf_type(), _M_mode(__mode), _M_string(__a)
170  { }
171 
172  explicit
173  basic_stringbuf(__string_type&& __s,
174  ios_base::openmode __mode = ios_base::in
175  | ios_base::out)
176  : __streambuf_type(), _M_mode(__mode), _M_string(std::move(__s))
177  { _M_stringbuf_init(__mode); }
178 
179  template<typename _SAlloc>
180  basic_stringbuf(const basic_string<_CharT, _Traits, _SAlloc>& __s,
181  const allocator_type& __a)
182  : basic_stringbuf(__s, ios_base::in | std::ios_base::out, __a)
183  { }
184 
185  template<typename _SAlloc>
186  basic_stringbuf(const basic_string<_CharT, _Traits, _SAlloc>& __s,
187  ios_base::openmode __mode,
188  const allocator_type& __a)
189  : __streambuf_type(), _M_mode(__mode),
190  _M_string(__s.data(), __s.size(), __a)
191  { _M_stringbuf_init(__mode); }
192 
193  template<typename _SAlloc>
194  explicit
195  basic_stringbuf(const basic_string<_CharT, _Traits, _SAlloc>& __s,
196  ios_base::openmode __mode = ios_base::in
197  | ios_base::out)
198  : basic_stringbuf(__s, __mode, allocator_type{})
199  { }
200 
201  basic_stringbuf(basic_stringbuf&& __rhs, const allocator_type& __a)
202  : basic_stringbuf(std::move(__rhs), __a, __xfer_bufptrs(__rhs, this))
203  { __rhs._M_sync(const_cast<char_type*>(__rhs._M_string.data()), 0, 0); }
204 
205  allocator_type get_allocator() const noexcept
206  { return _M_string.get_allocator(); }
207 #endif // C++20
208 
209  // 27.8.2.2 Assign and swap:
210 
211  basic_stringbuf&
212  operator=(const basic_stringbuf&) = delete;
213 
214  basic_stringbuf&
215  operator=(basic_stringbuf&& __rhs)
216  {
217  __xfer_bufptrs __st{__rhs, this};
218  const __streambuf_type& __base = __rhs;
219  __streambuf_type::operator=(__base);
220  this->pubimbue(__rhs.getloc());
221  _M_mode = __rhs._M_mode;
222  _M_string = std::move(__rhs._M_string);
223  __rhs._M_sync(const_cast<char_type*>(__rhs._M_string.data()), 0, 0);
224  return *this;
225  }
226 
227  void
228  swap(basic_stringbuf& __rhs) noexcept(_Noexcept_swap::value)
229  {
230  __xfer_bufptrs __l_st{*this, std::__addressof(__rhs)};
231  __xfer_bufptrs __r_st{__rhs, this};
232  __streambuf_type& __base = __rhs;
233  __streambuf_type::swap(__base);
234  __rhs.pubimbue(this->pubimbue(__rhs.getloc()));
235  std::swap(_M_mode, __rhs._M_mode);
236  std::swap(_M_string, __rhs._M_string); // XXX not exception safe
237  }
238 #endif // C++11
239 
240  // Getters and setters:
241 
242  /**
243  * @brief Copying out the string buffer.
244  * @return A copy of one of the underlying sequences.
245  *
246  * <em>If the buffer is only created in input mode, the underlying
247  * character sequence is equal to the input sequence; otherwise, it
248  * is equal to the output sequence.</em> [27.7.1.2]/1
249  */
250  _GLIBCXX_NODISCARD
251  __string_type
252  str() const _GLIBCXX_LVAL_REF_QUAL
253  {
254  __string_type __ret(_M_string.get_allocator());
255  if (char_type* __hi = _M_high_mark())
256  __ret.assign(this->pbase(), __hi);
257  else
258  __ret = _M_string;
259  return __ret;
260  }
261 
262 #if __cplusplus > 201703L
263 #if _GLIBCXX_USE_CXX11_ABI
264 #if __cpp_concepts
265  template<__allocator_like _SAlloc>
266  _GLIBCXX_NODISCARD
267  basic_string<_CharT, _Traits, _SAlloc>
268  str(const _SAlloc& __sa) const
269  {
270  auto __sv = view();
271  return { __sv.data(), __sv.size(), __sa };
272  }
273 #endif
274 
275  _GLIBCXX_NODISCARD
276  __string_type
277  str() &&
278  {
279  if (char_type* __hi = _M_high_mark())
280  {
281  // Set length to end of character sequence and add null terminator.
282  _M_string._M_set_length(_M_high_mark() - this->pbase());
283  }
284  auto __str = std::move(_M_string);
285  _M_string.clear();
286  _M_sync(_M_string.data(), 0, 0);
287  return __str;
288  }
289 #endif // cxx11 ABI
290 
291  _GLIBCXX_SSTREAM_ALWAYS_INLINE
292  basic_string_view<char_type, traits_type>
293  view() const noexcept
294  {
295  if (char_type* __hi = _M_high_mark())
296  return { this->pbase(), __hi };
297  else
298  return _M_string;
299  }
300 #endif // C++20
301 
302  /**
303  * @brief Setting a new buffer.
304  * @param __s The string to use as a new sequence.
305  *
306  * Deallocates any previous stored sequence, then copies @a s to
307  * use as a new one.
308  */
309  void
310  str(const __string_type& __s)
311  {
312  // Cannot use _M_string = __s, since v3 strings are COW
313  // (not always true now but assign() always works).
314  _M_string.assign(__s.data(), __s.size());
315  _M_stringbuf_init(_M_mode);
316  }
317 
318 #if __cplusplus > 201703L && _GLIBCXX_USE_CXX11_ABI
319 #if __cpp_concepts
320  template<__allocator_like _SAlloc>
321  requires (!is_same_v<_SAlloc, _Alloc>)
322  void
323  str(const basic_string<_CharT, _Traits, _SAlloc>& __s)
324  {
325  _M_string.assign(__s.data(), __s.size());
326  _M_stringbuf_init(_M_mode);
327  }
328 #endif
329 
330  void
331  str(__string_type&& __s)
332  {
333  _M_string = std::move(__s);
334  _M_stringbuf_init(_M_mode);
335  }
336 #endif
337 
338  protected:
339  // Common initialization code goes here.
340  void
341  _M_stringbuf_init(ios_base::openmode __mode)
342  {
343  _M_mode = __mode;
344  __size_type __len = 0;
345  if (_M_mode & (ios_base::ate | ios_base::app))
346  __len = _M_string.size();
347  _M_sync(const_cast<char_type*>(_M_string.data()), 0, __len);
348  }
349 
350  virtual streamsize
351  showmanyc()
352  {
353  streamsize __ret = -1;
354  if (_M_mode & ios_base::in)
355  {
356  _M_update_egptr();
357  __ret = this->egptr() - this->gptr();
358  }
359  return __ret;
360  }
361 
362  virtual int_type
363  underflow();
364 
365  virtual int_type
366  pbackfail(int_type __c = traits_type::eof());
367 
368  virtual int_type
369  overflow(int_type __c = traits_type::eof());
370 
371  /**
372  * @brief Manipulates the buffer.
373  * @param __s Pointer to a buffer area.
374  * @param __n Size of @a __s.
375  * @return @c this
376  *
377  * If no buffer has already been created, and both @a __s and @a __n are
378  * non-zero, then @c __s is used as a buffer; see
379  * https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering
380  * for more.
381  */
382  virtual __streambuf_type*
383  setbuf(char_type* __s, streamsize __n)
384  {
385  if (__s && __n >= 0)
386  {
387  // This is implementation-defined behavior, and assumes
388  // that an external char_type array of length __n exists
389  // and has been pre-allocated. If this is not the case,
390  // things will quickly blow up.
391 
392  // Step 1: Destroy the current internal array.
393  _M_string.clear();
394 
395  // Step 2: Use the external array.
396  _M_sync(__s, __n, 0);
397  }
398  return this;
399  }
400 
401  virtual pos_type
402  seekoff(off_type __off, ios_base::seekdir __way,
403  ios_base::openmode __mode = ios_base::in | ios_base::out);
404 
405  virtual pos_type
406  seekpos(pos_type __sp,
407  ios_base::openmode __mode = ios_base::in | ios_base::out);
408 
409  // Internal function for correctly updating the internal buffer
410  // for a particular _M_string, due to initialization or re-sizing
411  // of an existing _M_string.
412  void
413  _M_sync(char_type* __base, __size_type __i, __size_type __o);
414 
415  // Internal function for correctly updating egptr() to the actual
416  // string end.
417  void
418  _M_update_egptr()
419  {
420  if (char_type* __pptr = this->pptr())
421  {
422  char_type* __egptr = this->egptr();
423  if (!__egptr || __pptr > __egptr)
424  {
425  if (_M_mode & ios_base::in)
426  this->setg(this->eback(), this->gptr(), __pptr);
427  else
428  this->setg(__pptr, __pptr, __pptr);
429  }
430  }
431  }
432 
433  // Works around the issue with pbump, part of the protected
434  // interface of basic_streambuf, taking just an int.
435  void
436  _M_pbump(char_type* __pbeg, char_type* __pend, off_type __off);
437 
438  private:
439  // Return a pointer to the end of the underlying character sequence.
440  // This might not be the same character as _M_string.end() because
441  // basic_stringbuf::overflow might have written to unused capacity
442  // in _M_string without updating its length.
443  __attribute__((__always_inline__))
444  char_type*
445  _M_high_mark() const _GLIBCXX_NOEXCEPT
446  {
447  if (char_type* __pptr = this->pptr())
448  {
449  char_type* __egptr = this->egptr();
450  if (!__egptr || __pptr > __egptr)
451  return __pptr; // Underlying sequence is [pbase, pptr).
452  else
453  return __egptr; // Underlying sequence is [pbase, egptr).
454  }
455  return 0; // Underlying character sequence is just _M_string.
456  }
457 
458 #if __cplusplus >= 201103L
459 #if _GLIBCXX_USE_CXX11_ABI
460  // This type captures the state of the gptr / pptr pointers as offsets
461  // so they can be restored in another object after moving the string.
462  struct __xfer_bufptrs
463  {
464  __xfer_bufptrs(const basic_stringbuf& __from, basic_stringbuf* __to)
465  : _M_to{__to}, _M_goff{-1, -1, -1}, _M_poff{-1, -1, -1}
466  {
467  const _CharT* const __str = __from._M_string.data();
468  const _CharT* __end = nullptr;
469  if (__from.eback())
470  {
471  _M_goff[0] = __from.eback() - __str;
472  _M_goff[1] = __from.gptr() - __str;
473  _M_goff[2] = __from.egptr() - __str;
474  __end = __from.egptr();
475  }
476  if (__from.pbase())
477  {
478  _M_poff[0] = __from.pbase() - __str;
479  _M_poff[1] = __from.pptr() - __from.pbase();
480  _M_poff[2] = __from.epptr() - __str;
481  if (!__end || __from.pptr() > __end)
482  __end = __from.pptr();
483  }
484 
485  // Set _M_string length to the greater of the get and put areas.
486  if (__end)
487  {
488  // The const_cast avoids changing this constructor's signature,
489  // because it is exported from the dynamic library.
490  auto& __mut_from = const_cast<basic_stringbuf&>(__from);
491  __mut_from._M_string._M_length(__end - __str);
492  }
493  }
494 
495  ~__xfer_bufptrs()
496  {
497  char_type* __str = const_cast<char_type*>(_M_to->_M_string.data());
498  if (_M_goff[0] != -1)
499  _M_to->setg(__str+_M_goff[0], __str+_M_goff[1], __str+_M_goff[2]);
500  if (_M_poff[0] != -1)
501  _M_to->_M_pbump(__str+_M_poff[0], __str+_M_poff[2], _M_poff[1]);
502  }
503 
504  basic_stringbuf* _M_to;
505  off_type _M_goff[3];
506  off_type _M_poff[3];
507  };
508 #else
509  // This type does nothing when using Copy-On-Write strings.
510  struct __xfer_bufptrs
511  {
512  __xfer_bufptrs(const basic_stringbuf&, basic_stringbuf*) { }
513  };
514 #endif
515 
516  // The move constructor initializes an __xfer_bufptrs temporary then
517  // delegates to this constructor to performs moves during its lifetime.
518  basic_stringbuf(basic_stringbuf&& __rhs, __xfer_bufptrs&&)
519  : __streambuf_type(static_cast<const __streambuf_type&>(__rhs)),
520  _M_mode(__rhs._M_mode), _M_string(std::move(__rhs._M_string))
521  { }
522 
523 #if __cplusplus > 201703L && _GLIBCXX_USE_CXX11_ABI
524  // The move constructor initializes an __xfer_bufptrs temporary then
525  // delegates to this constructor to performs moves during its lifetime.
526  basic_stringbuf(basic_stringbuf&& __rhs, const allocator_type& __a,
527  __xfer_bufptrs&&)
528  : __streambuf_type(static_cast<const __streambuf_type&>(__rhs)),
529  _M_mode(__rhs._M_mode), _M_string(std::move(__rhs._M_string), __a)
530  { }
531 #endif
532 #endif // C++11
533  };
534 
535 
536  // [27.7.2] Template class basic_istringstream
537  /**
538  * @brief Controlling input for std::string.
539  * @ingroup io
540  *
541  * @tparam _CharT Type of character stream.
542  * @tparam _Traits Traits for character type, defaults to
543  * char_traits<_CharT>.
544  * @tparam _Alloc Allocator type, defaults to allocator<_CharT>.
545  *
546  * This class supports reading from objects of type std::basic_string,
547  * using the inherited functions from std::basic_istream. To control
548  * the associated sequence, an instance of std::basic_stringbuf is used,
549  * which this page refers to as @c sb.
550  */
551  template<typename _CharT, typename _Traits, typename _Alloc>
552  class basic_istringstream : public basic_istream<_CharT, _Traits>
553  {
554  public:
555  // Types:
556  typedef _CharT char_type;
557  typedef _Traits traits_type;
558  // _GLIBCXX_RESOLVE_LIB_DEFECTS
559  // 251. basic_stringbuf missing allocator_type
560  typedef _Alloc allocator_type;
561  typedef typename traits_type::int_type int_type;
562  typedef typename traits_type::pos_type pos_type;
563  typedef typename traits_type::off_type off_type;
564 
565  // Non-standard types:
566  typedef basic_string<_CharT, _Traits, _Alloc> __string_type;
567  typedef basic_stringbuf<_CharT, _Traits, _Alloc> __stringbuf_type;
568  typedef basic_istream<char_type, traits_type> __istream_type;
569 
570  private:
571  __stringbuf_type _M_stringbuf;
572 
573  public:
574  // Constructors:
575 
576  /**
577  * @brief Default constructor starts with an empty string buffer.
578  *
579  * Initializes @c sb using @c in, and passes @c &sb to the base
580  * class initializer. Does not allocate any buffer.
581  *
582  * That's a lie. We initialize the base class with NULL, because the
583  * string class does its own memory management.
584  */
585  basic_istringstream()
586  : __istream_type(), _M_stringbuf(ios_base::in)
587  { this->init(&_M_stringbuf); }
588 
589  /**
590  * @brief Starts with an empty string buffer.
591  * @param __mode Whether the buffer can read, or write, or both.
592  *
593  * @c ios_base::in is automatically included in @a __mode.
594  *
595  * Initializes @c sb using @c __mode|in, and passes @c &sb to the base
596  * class initializer. Does not allocate any buffer.
597  *
598  * That's a lie. We initialize the base class with NULL, because the
599  * string class does its own memory management.
600  */
601  explicit
602  basic_istringstream(ios_base::openmode __mode)
603  : __istream_type(), _M_stringbuf(__mode | ios_base::in)
604  { this->init(&_M_stringbuf); }
605 
606  /**
607  * @brief Starts with an existing string buffer.
608  * @param __str A string to copy as a starting buffer.
609  * @param __mode Whether the buffer can read, or write, or both.
610  *
611  * @c ios_base::in is automatically included in @a mode.
612  *
613  * Initializes @c sb using @a str and @c mode|in, and passes @c &sb
614  * to the base class initializer.
615  *
616  * That's a lie. We initialize the base class with NULL, because the
617  * string class does its own memory management.
618  */
619  explicit
620  basic_istringstream(const __string_type& __str,
621  ios_base::openmode __mode = ios_base::in)
622  : __istream_type(), _M_stringbuf(__str, __mode | ios_base::in)
623  { this->init(&_M_stringbuf); }
624 
625  /**
626  * @brief The destructor does nothing.
627  *
628  * The buffer is deallocated by the stringbuf object, not the
629  * formatting stream.
630  */
631  ~basic_istringstream()
632  { }
633 
634 #if __cplusplus >= 201103L
635  basic_istringstream(const basic_istringstream&) = delete;
636 
637  basic_istringstream(basic_istringstream&& __rhs)
638  : __istream_type(std::move(__rhs)),
639  _M_stringbuf(std::move(__rhs._M_stringbuf))
640  { __istream_type::set_rdbuf(&_M_stringbuf); }
641 
642 #if __cplusplus > 201703L && _GLIBCXX_USE_CXX11_ABI
643  basic_istringstream(ios_base::openmode __mode, const allocator_type& __a)
644  : __istream_type(), _M_stringbuf(__mode | ios_base::in, __a)
645  { this->init(std::__addressof(_M_stringbuf)); }
646 
647  explicit
648  basic_istringstream(__string_type&& __str,
649  ios_base::openmode __mode = ios_base::in)
650  : __istream_type(), _M_stringbuf(std::move(__str), __mode | ios_base::in)
651  { this->init(std::__addressof(_M_stringbuf)); }
652 
653  template<typename _SAlloc>
654  basic_istringstream(const basic_string<_CharT, _Traits, _SAlloc>& __str,
655  const allocator_type& __a)
656  : basic_istringstream(__str, ios_base::in, __a)
657  { }
658 
659  template<typename _SAlloc>
660  basic_istringstream(const basic_string<_CharT, _Traits, _SAlloc>& __str,
661  ios_base::openmode __mode,
662  const allocator_type& __a)
663  : __istream_type(), _M_stringbuf(__str, __mode | ios_base::in, __a)
664  { this->init(std::__addressof(_M_stringbuf)); }
665 
666  template<typename _SAlloc>
667  explicit
668  basic_istringstream(const basic_string<_CharT, _Traits, _SAlloc>& __str,
669  ios_base::openmode __mode = ios_base::in)
670  : basic_istringstream(__str, __mode, allocator_type())
671  { }
672 #endif // C++20
673 
674  // 27.8.3.2 Assign and swap:
675 
676  basic_istringstream&
677  operator=(const basic_istringstream&) = delete;
678 
679  basic_istringstream&
680  operator=(basic_istringstream&& __rhs)
681  {
682  __istream_type::operator=(std::move(__rhs));
683  _M_stringbuf = std::move(__rhs._M_stringbuf);
684  return *this;
685  }
686 
687  void
688  swap(basic_istringstream& __rhs)
689  {
690  __istream_type::swap(__rhs);
691  _M_stringbuf.swap(__rhs._M_stringbuf);
692  }
693 #endif // C++11
694 
695  // Members:
696  /**
697  * @brief Accessing the underlying buffer.
698  * @return The current basic_stringbuf buffer.
699  *
700  * This hides both signatures of std::basic_ios::rdbuf().
701  */
702  _GLIBCXX_NODISCARD
703  __stringbuf_type*
704  rdbuf() const
705  { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
706 
707  /**
708  * @brief Copying out the string buffer.
709  * @return @c rdbuf()->str()
710  */
711  _GLIBCXX_NODISCARD
712  __string_type
713  str() const _GLIBCXX_LVAL_REF_QUAL
714  { return _M_stringbuf.str(); }
715 
716 #if __cplusplus > 201703L
717 #if _GLIBCXX_USE_CXX11_ABI
718 #if __cpp_concepts
719  template<__allocator_like _SAlloc>
720  _GLIBCXX_NODISCARD
721  basic_string<_CharT, _Traits, _SAlloc>
722  str(const _SAlloc& __sa) const
723  { return _M_stringbuf.str(__sa); }
724 #endif
725 
726  _GLIBCXX_NODISCARD
727  __string_type
728  str() &&
729  { return std::move(_M_stringbuf).str(); }
730 #endif // cxx11 ABI
731 
732  _GLIBCXX_SSTREAM_ALWAYS_INLINE
733  basic_string_view<char_type, traits_type>
734  view() const noexcept
735  { return _M_stringbuf.view(); }
736 #endif // C++20
737 
738  /**
739  * @brief Setting a new buffer.
740  * @param __s The string to use as a new sequence.
741  *
742  * Calls @c rdbuf()->str(s).
743  */
744  void
745  str(const __string_type& __s)
746  { _M_stringbuf.str(__s); }
747 
748 #if __cplusplus > 201703L && _GLIBCXX_USE_CXX11_ABI
749 #if __cpp_concepts
750  template<__allocator_like _SAlloc>
751  requires (!is_same_v<_SAlloc, _Alloc>)
752  void
753  str(const basic_string<_CharT, _Traits, _SAlloc>& __s)
754  { _M_stringbuf.str(__s); }
755 #endif
756 
757  void
758  str(__string_type&& __s)
759  { _M_stringbuf.str(std::move(__s)); }
760 #endif
761  };
762 
763 
764  // [27.7.3] Template class basic_ostringstream
765  /**
766  * @brief Controlling output for std::string.
767  * @ingroup io
768  *
769  * @tparam _CharT Type of character stream.
770  * @tparam _Traits Traits for character type, defaults to
771  * char_traits<_CharT>.
772  * @tparam _Alloc Allocator type, defaults to allocator<_CharT>.
773  *
774  * This class supports writing to objects of type std::basic_string,
775  * using the inherited functions from std::basic_ostream. To control
776  * the associated sequence, an instance of std::basic_stringbuf is used,
777  * which this page refers to as @c sb.
778  */
779  template <typename _CharT, typename _Traits, typename _Alloc>
780  class basic_ostringstream : public basic_ostream<_CharT, _Traits>
781  {
782  public:
783  // Types:
784  typedef _CharT char_type;
785  typedef _Traits traits_type;
786  // _GLIBCXX_RESOLVE_LIB_DEFECTS
787  // 251. basic_stringbuf missing allocator_type
788  typedef _Alloc allocator_type;
789  typedef typename traits_type::int_type int_type;
790  typedef typename traits_type::pos_type pos_type;
791  typedef typename traits_type::off_type off_type;
792 
793  // Non-standard types:
794  typedef basic_string<_CharT, _Traits, _Alloc> __string_type;
795  typedef basic_stringbuf<_CharT, _Traits, _Alloc> __stringbuf_type;
796  typedef basic_ostream<char_type, traits_type> __ostream_type;
797 
798  private:
799  __stringbuf_type _M_stringbuf;
800 
801  public:
802  // Constructors/destructor:
803 
804  /**
805  * @brief Default constructor starts with an empty string buffer.
806  *
807  * Initializes @c sb using @c mode|out, and passes @c &sb to the base
808  * class initializer. Does not allocate any buffer.
809  *
810  * That's a lie. We initialize the base class with NULL, because the
811  * string class does its own memory management.
812  */
813  basic_ostringstream()
814  : __ostream_type(), _M_stringbuf(ios_base::out)
815  { this->init(&_M_stringbuf); }
816 
817  /**
818  * @brief Starts with an empty string buffer.
819  * @param __mode Whether the buffer can read, or write, or both.
820  *
821  * @c ios_base::out is automatically included in @a mode.
822  *
823  * Initializes @c sb using @c mode|out, and passes @c &sb to the base
824  * class initializer. Does not allocate any buffer.
825  *
826  * That's a lie. We initialize the base class with NULL, because the
827  * string class does its own memory management.
828  */
829  explicit
830  basic_ostringstream(ios_base::openmode __mode)
831  : __ostream_type(), _M_stringbuf(__mode | ios_base::out)
832  { this->init(&_M_stringbuf); }
833 
834  /**
835  * @brief Starts with an existing string buffer.
836  * @param __str A string to copy as a starting buffer.
837  * @param __mode Whether the buffer can read, or write, or both.
838  *
839  * @c ios_base::out is automatically included in @a mode.
840  *
841  * Initializes @c sb using @a str and @c mode|out, and passes @c &sb
842  * to the base class initializer.
843  *
844  * That's a lie. We initialize the base class with NULL, because the
845  * string class does its own memory management.
846  */
847  explicit
848  basic_ostringstream(const __string_type& __str,
849  ios_base::openmode __mode = ios_base::out)
850  : __ostream_type(), _M_stringbuf(__str, __mode | ios_base::out)
851  { this->init(&_M_stringbuf); }
852 
853  /**
854  * @brief The destructor does nothing.
855  *
856  * The buffer is deallocated by the stringbuf object, not the
857  * formatting stream.
858  */
859  ~basic_ostringstream()
860  { }
861 
862 #if __cplusplus >= 201103L
863  basic_ostringstream(const basic_ostringstream&) = delete;
864 
865  basic_ostringstream(basic_ostringstream&& __rhs)
866  : __ostream_type(std::move(__rhs)),
867  _M_stringbuf(std::move(__rhs._M_stringbuf))
868  { __ostream_type::set_rdbuf(&_M_stringbuf); }
869 
870 #if __cplusplus > 201703L && _GLIBCXX_USE_CXX11_ABI
871  basic_ostringstream(ios_base::openmode __mode, const allocator_type& __a)
872  : __ostream_type(), _M_stringbuf(__mode | ios_base::out, __a)
873  { this->init(std::__addressof(_M_stringbuf)); }
874 
875  explicit
876  basic_ostringstream(__string_type&& __str,
877  ios_base::openmode __mode = ios_base::out)
878  : __ostream_type(), _M_stringbuf(std::move(__str), __mode | ios_base::out)
879  { this->init(std::__addressof(_M_stringbuf)); }
880 
881  template<typename _SAlloc>
882  basic_ostringstream(const basic_string<_CharT, _Traits, _SAlloc>& __str,
883  const allocator_type& __a)
884  : basic_ostringstream(__str, ios_base::out, __a)
885  { }
886 
887  template<typename _SAlloc>
888  basic_ostringstream(const basic_string<_CharT, _Traits, _SAlloc>& __str,
889  ios_base::openmode __mode,
890  const allocator_type& __a)
891  : __ostream_type(), _M_stringbuf(__str, __mode | ios_base::out, __a)
892  { this->init(std::__addressof(_M_stringbuf)); }
893 
894  template<typename _SAlloc>
895  explicit
896  basic_ostringstream(const basic_string<_CharT, _Traits, _SAlloc>& __str,
897  ios_base::openmode __mode = ios_base::out)
898  : basic_ostringstream(__str, __mode, allocator_type())
899  { }
900 #endif // C++20
901 
902  // 27.8.3.2 Assign and swap:
903 
904  basic_ostringstream&
905  operator=(const basic_ostringstream&) = delete;
906 
907  basic_ostringstream&
908  operator=(basic_ostringstream&& __rhs)
909  {
910  __ostream_type::operator=(std::move(__rhs));
911  _M_stringbuf = std::move(__rhs._M_stringbuf);
912  return *this;
913  }
914 
915  void
916  swap(basic_ostringstream& __rhs)
917  {
918  __ostream_type::swap(__rhs);
919  _M_stringbuf.swap(__rhs._M_stringbuf);
920  }
921 #endif // C++11
922 
923  // Members:
924  /**
925  * @brief Accessing the underlying buffer.
926  * @return The current basic_stringbuf buffer.
927  *
928  * This hides both signatures of std::basic_ios::rdbuf().
929  */
930  _GLIBCXX_NODISCARD
931  __stringbuf_type*
932  rdbuf() const
933  { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
934 
935  /**
936  * @brief Copying out the string buffer.
937  * @return @c rdbuf()->str()
938  */
939  _GLIBCXX_NODISCARD
940  __string_type
941  str() const _GLIBCXX_LVAL_REF_QUAL
942  { return _M_stringbuf.str(); }
943 
944 #if __cplusplus > 201703L
945 #if _GLIBCXX_USE_CXX11_ABI
946 #if __cpp_concepts
947  template<__allocator_like _SAlloc>
948  _GLIBCXX_NODISCARD
949  basic_string<_CharT, _Traits, _SAlloc>
950  str(const _SAlloc& __sa) const
951  { return _M_stringbuf.str(__sa); }
952 #endif
953 
954  _GLIBCXX_NODISCARD
955  __string_type
956  str() &&
957  { return std::move(_M_stringbuf).str(); }
958 #endif // cxx11 ABI
959 
960  _GLIBCXX_SSTREAM_ALWAYS_INLINE
961  basic_string_view<char_type, traits_type>
962  view() const noexcept
963  { return _M_stringbuf.view(); }
964 #endif // C++20
965 
966  /**
967  * @brief Setting a new buffer.
968  * @param __s The string to use as a new sequence.
969  *
970  * Calls @c rdbuf()->str(s).
971  */
972  void
973  str(const __string_type& __s)
974  { _M_stringbuf.str(__s); }
975 
976 #if __cplusplus > 201703L && _GLIBCXX_USE_CXX11_ABI
977 #if __cpp_concepts
978  template<__allocator_like _SAlloc>
979  requires (!is_same_v<_SAlloc, _Alloc>)
980  void
981  str(const basic_string<_CharT, _Traits, _SAlloc>& __s)
982  { _M_stringbuf.str(__s); }
983 #endif
984 
985  void
986  str(__string_type&& __s)
987  { _M_stringbuf.str(std::move(__s)); }
988 #endif
989  };
990 
991 
992  // [27.7.4] Template class basic_stringstream
993  /**
994  * @brief Controlling input and output for std::string.
995  * @ingroup io
996  *
997  * @tparam _CharT Type of character stream.
998  * @tparam _Traits Traits for character type, defaults to
999  * char_traits<_CharT>.
1000  * @tparam _Alloc Allocator type, defaults to allocator<_CharT>.
1001  *
1002  * This class supports reading from and writing to objects of type
1003  * std::basic_string, using the inherited functions from
1004  * std::basic_iostream. To control the associated sequence, an instance
1005  * of std::basic_stringbuf is used, which this page refers to as @c sb.
1006  */
1007  template <typename _CharT, typename _Traits, typename _Alloc>
1008  class basic_stringstream : public basic_iostream<_CharT, _Traits>
1009  {
1010  public:
1011  // Types:
1012  typedef _CharT char_type;
1013  typedef _Traits traits_type;
1014  // _GLIBCXX_RESOLVE_LIB_DEFECTS
1015  // 251. basic_stringbuf missing allocator_type
1016  typedef _Alloc allocator_type;
1017  typedef typename traits_type::int_type int_type;
1018  typedef typename traits_type::pos_type pos_type;
1019  typedef typename traits_type::off_type off_type;
1020 
1021  // Non-standard Types:
1022  typedef basic_string<_CharT, _Traits, _Alloc> __string_type;
1023  typedef basic_stringbuf<_CharT, _Traits, _Alloc> __stringbuf_type;
1024  typedef basic_iostream<char_type, traits_type> __iostream_type;
1025 
1026  private:
1027  __stringbuf_type _M_stringbuf;
1028 
1029  public:
1030  // Constructors/destructors
1031 
1032  /**
1033  * @brief Default constructor starts with an empty string buffer.
1034  *
1035  * Initializes @c sb using the mode @c in|out, and passes @c &sb
1036  * to the base class initializer. Does not allocate any buffer.
1037  *
1038  * That's a lie. We initialize the base class with NULL, because the
1039  * string class does its own memory management.
1040  */
1041  basic_stringstream()
1042  : __iostream_type(), _M_stringbuf(ios_base::out | ios_base::in)
1043  { this->init(&_M_stringbuf); }
1044 
1045  /**
1046  * @brief Starts with an empty string buffer.
1047  * @param __m Whether the buffer can read, or write, or both.
1048  *
1049  * Initializes @c sb using the mode from @c __m, and passes @c &sb
1050  * to the base class initializer. Does not allocate any buffer.
1051  *
1052  * That's a lie. We initialize the base class with NULL, because the
1053  * string class does its own memory management.
1054  */
1055  explicit
1056  basic_stringstream(ios_base::openmode __m)
1057  : __iostream_type(), _M_stringbuf(__m)
1058  { this->init(&_M_stringbuf); }
1059 
1060  /**
1061  * @brief Starts with an existing string buffer.
1062  * @param __str A string to copy as a starting buffer.
1063  * @param __m Whether the buffer can read, or write, or both.
1064  *
1065  * Initializes @c sb using @a __str and @c __m, and passes @c &sb
1066  * to the base class initializer.
1067  *
1068  * That's a lie. We initialize the base class with NULL, because the
1069  * string class does its own memory management.
1070  */
1071  explicit
1072  basic_stringstream(const __string_type& __str,
1073  ios_base::openmode __m = ios_base::out | ios_base::in)
1074  : __iostream_type(), _M_stringbuf(__str, __m)
1075  { this->init(&_M_stringbuf); }
1076 
1077  /**
1078  * @brief The destructor does nothing.
1079  *
1080  * The buffer is deallocated by the stringbuf object, not the
1081  * formatting stream.
1082  */
1083  ~basic_stringstream()
1084  { }
1085 
1086 #if __cplusplus >= 201103L
1087  basic_stringstream(const basic_stringstream&) = delete;
1088 
1089  basic_stringstream(basic_stringstream&& __rhs)
1090  : __iostream_type(std::move(__rhs)),
1091  _M_stringbuf(std::move(__rhs._M_stringbuf))
1092  { __iostream_type::set_rdbuf(&_M_stringbuf); }
1093 
1094 #if __cplusplus > 201703L && _GLIBCXX_USE_CXX11_ABI
1095  basic_stringstream(ios_base::openmode __mode, const allocator_type& __a)
1096  : __iostream_type(), _M_stringbuf(__mode, __a)
1097  { this->init(&_M_stringbuf); }
1098 
1099  explicit
1100  basic_stringstream(__string_type&& __str,
1101  ios_base::openmode __mode = ios_base::in
1102  | ios_base::out)
1103  : __iostream_type(), _M_stringbuf(std::move(__str), __mode)
1104  { this->init(std::__addressof(_M_stringbuf)); }
1105 
1106  template<typename _SAlloc>
1107  basic_stringstream(const basic_string<_CharT, _Traits, _SAlloc>& __str,
1108  const allocator_type& __a)
1109  : basic_stringstream(__str, ios_base::in | ios_base::out, __a)
1110  { }
1111 
1112  template<typename _SAlloc>
1113  basic_stringstream(const basic_string<_CharT, _Traits, _SAlloc>& __str,
1114  ios_base::openmode __mode,
1115  const allocator_type& __a)
1116  : __iostream_type(), _M_stringbuf(__str, __mode, __a)
1117  { this->init(std::__addressof(_M_stringbuf)); }
1118 
1119  template<typename _SAlloc>
1120  explicit
1121  basic_stringstream(const basic_string<_CharT, _Traits, _SAlloc>& __str,
1122  ios_base::openmode __mode = ios_base::in
1123  | ios_base::out)
1124  : basic_stringstream(__str, __mode, allocator_type())
1125  { }
1126 #endif // C++20
1127 
1128  // 27.8.3.2 Assign and swap:
1129 
1130  basic_stringstream&
1131  operator=(const basic_stringstream&) = delete;
1132 
1133  basic_stringstream&
1134  operator=(basic_stringstream&& __rhs)
1135  {
1136  __iostream_type::operator=(std::move(__rhs));
1137  _M_stringbuf = std::move(__rhs._M_stringbuf);
1138  return *this;
1139  }
1140 
1141  void
1142  swap(basic_stringstream& __rhs)
1143  {
1144  __iostream_type::swap(__rhs);
1145  _M_stringbuf.swap(__rhs._M_stringbuf);
1146  }
1147 #endif // C++11
1148 
1149  // Members:
1150  /**
1151  * @brief Accessing the underlying buffer.
1152  * @return The current basic_stringbuf buffer.
1153  *
1154  * This hides both signatures of std::basic_ios::rdbuf().
1155  */
1156  _GLIBCXX_NODISCARD
1157  __stringbuf_type*
1158  rdbuf() const
1159  { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
1160 
1161  /**
1162  * @brief Copying out the string buffer.
1163  * @return @c rdbuf()->str()
1164  */
1165  _GLIBCXX_NODISCARD
1166  __string_type
1167  str() const _GLIBCXX_LVAL_REF_QUAL
1168  { return _M_stringbuf.str(); }
1169 
1170 #if __cplusplus > 201703L
1171 #if _GLIBCXX_USE_CXX11_ABI
1172 #if __cpp_concepts
1173  template<__allocator_like _SAlloc>
1174  _GLIBCXX_NODISCARD
1175  basic_string<_CharT, _Traits, _SAlloc>
1176  str(const _SAlloc& __sa) const
1177  { return _M_stringbuf.str(__sa); }
1178 #endif
1179 
1180  _GLIBCXX_NODISCARD
1181  __string_type
1182  str() &&
1183  { return std::move(_M_stringbuf).str(); }
1184 #endif // cxx11 ABI
1185 
1186  _GLIBCXX_SSTREAM_ALWAYS_INLINE
1187  basic_string_view<char_type, traits_type>
1188  view() const noexcept
1189  { return _M_stringbuf.view(); }
1190 #endif // C++20
1191 
1192  /**
1193  * @brief Setting a new buffer.
1194  * @param __s The string to use as a new sequence.
1195  *
1196  * Calls @c rdbuf()->str(s).
1197  */
1198  void
1199  str(const __string_type& __s)
1200  { _M_stringbuf.str(__s); }
1201 
1202 #if __cplusplus > 201703L && _GLIBCXX_USE_CXX11_ABI
1203 #if __cpp_concepts
1204  template<__allocator_like _SAlloc>
1205  requires (!is_same_v<_SAlloc, _Alloc>)
1206  void
1207  str(const basic_string<_CharT, _Traits, _SAlloc>& __s)
1208  { _M_stringbuf.str(__s); }
1209 #endif
1210 
1211  void
1212  str(__string_type&& __s)
1213  { _M_stringbuf.str(std::move(__s)); }
1214 #endif
1215  };
1216 
1217 #if __cplusplus >= 201103L
1218  /// Swap specialization for stringbufs.
1219  template <class _CharT, class _Traits, class _Allocator>
1220  inline void
1221  swap(basic_stringbuf<_CharT, _Traits, _Allocator>& __x,
1222  basic_stringbuf<_CharT, _Traits, _Allocator>& __y)
1223  noexcept(noexcept(__x.swap(__y)))
1224  { __x.swap(__y); }
1225 
1226  /// Swap specialization for istringstreams.
1227  template <class _CharT, class _Traits, class _Allocator>
1228  inline void
1229  swap(basic_istringstream<_CharT, _Traits, _Allocator>& __x,
1230  basic_istringstream<_CharT, _Traits, _Allocator>& __y)
1231  { __x.swap(__y); }
1232 
1233  /// Swap specialization for ostringstreams.
1234  template <class _CharT, class _Traits, class _Allocator>
1235  inline void
1236  swap(basic_ostringstream<_CharT, _Traits, _Allocator>& __x,
1237  basic_ostringstream<_CharT, _Traits, _Allocator>& __y)
1238  { __x.swap(__y); }
1239 
1240  /// Swap specialization for stringstreams.
1241  template <class _CharT, class _Traits, class _Allocator>
1242  inline void
1243  swap(basic_stringstream<_CharT, _Traits, _Allocator>& __x,
1244  basic_stringstream<_CharT, _Traits, _Allocator>& __y)
1245  { __x.swap(__y); }
1246 #endif // C++11
1247 
1248 _GLIBCXX_END_NAMESPACE_CXX11
1249 _GLIBCXX_END_NAMESPACE_VERSION
1250 } // namespace
1251 
1252 #undef _GLIBCXX_SSTREAM_ALWAYS_INLINE
1253 #undef _GLIBCXX_LVAL_REF_QUAL
1254 
1255 #include <bits/sstream.tcc>
1256 
1257 #endif /* _GLIBCXX_SSTREAM */