1// String based streams -*- C++ -*-
2
3// Copyright (C) 1997-2018 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#pragma GCC system_header
37
38#include <istream>
39#include <ostream>
40
41namespace std _GLIBCXX_VISIBILITY(default)
42{
43_GLIBCXX_BEGIN_NAMESPACE_VERSION
44_GLIBCXX_BEGIN_NAMESPACE_CXX11
45
46  // [27.7.1] template class basic_stringbuf
47  /**
48   *  @brief  The actual work of input and output (for std::string).
49   *  @ingroup io
50   *
51   *  @tparam _CharT  Type of character stream.
52   *  @tparam _Traits  Traits for character type, defaults to
53   *                   char_traits<_CharT>.
54   *  @tparam _Alloc  Allocator type, defaults to allocator<_CharT>.
55   *
56   *  This class associates either or both of its input and output sequences
57   *  with a sequence of characters, which can be initialized from, or made
58   *  available as, a @c std::basic_string.  (Paraphrased from [27.7.1]/1.)
59   *
60   *  For this class, open modes (of type @c ios_base::openmode) have
61   *  @c in set if the input sequence can be read, and @c out set if the
62   *  output sequence can be written.
63  */
64  template<typename _CharT, typename _Traits, typename _Alloc>
65    class basic_stringbuf : public basic_streambuf<_CharT, _Traits>
66    {
67      struct __xfer_bufptrs;
68    public:
69      // Types:
70      typedef _CharT 					char_type;
71      typedef _Traits 					traits_type;
72      // _GLIBCXX_RESOLVE_LIB_DEFECTS
73      // 251. basic_stringbuf missing allocator_type
74      typedef _Alloc				       	allocator_type;
75      typedef typename traits_type::int_type 		int_type;
76      typedef typename traits_type::pos_type 		pos_type;
77      typedef typename traits_type::off_type 		off_type;
78
79      typedef basic_streambuf<char_type, traits_type>  	__streambuf_type;
80      typedef basic_string<char_type, _Traits, _Alloc> 	__string_type;
81      typedef typename __string_type::size_type		__size_type;
82
83    protected:
84      /// Place to stash in || out || in | out settings for current stringbuf.
85      ios_base::openmode 	_M_mode;
86
87      // Data Members:
88      __string_type 		_M_string;
89
90    public:
91      // Constructors:
92      /**
93       *  @brief  Starts with an empty string buffer.
94       *  @param  __mode  Whether the buffer can read, or write, or both.
95       *
96       *  The default constructor initializes the parent class using its
97       *  own default ctor.
98      */
99      explicit
100      basic_stringbuf(ios_base::openmode __mode = ios_base::in | ios_base::out)
101      : __streambuf_type(), _M_mode(__mode), _M_string()
102      { }
103
104      /**
105       *  @brief  Starts with an existing string buffer.
106       *  @param  __str  A string to copy as a starting buffer.
107       *  @param  __mode  Whether the buffer can read, or write, or both.
108       *
109       *  This constructor initializes the parent class using its
110       *  own default ctor.
111      */
112      explicit
113      basic_stringbuf(const __string_type& __str,
114		      ios_base::openmode __mode = ios_base::in | ios_base::out)
115      : __streambuf_type(), _M_mode(),
116	_M_string(__str.data(), __str.size(), __str.get_allocator())
117      { _M_stringbuf_init(__mode); }
118
119#if __cplusplus >= 201103L
120      basic_stringbuf(const basic_stringbuf&) = delete;
121
122      basic_stringbuf(basic_stringbuf&& __rhs)
123      : basic_stringbuf(std::move(__rhs), __xfer_bufptrs(__rhs, this))
124      { __rhs._M_sync(const_cast<char_type*>(__rhs._M_string.data()), 0, 0); }
125
126      // 27.8.2.2 Assign and swap:
127
128      basic_stringbuf&
129      operator=(const basic_stringbuf&) = delete;
130
131      basic_stringbuf&
132      operator=(basic_stringbuf&& __rhs)
133      {
134	__xfer_bufptrs __st{__rhs, this};
135	const __streambuf_type& __base = __rhs;
136	__streambuf_type::operator=(__base);
137	this->pubimbue(__rhs.getloc());
138	_M_mode = __rhs._M_mode;
139	_M_string = std::move(__rhs._M_string);
140	__rhs._M_sync(const_cast<char_type*>(__rhs._M_string.data()), 0, 0);
141	return *this;
142      }
143
144      void
145      swap(basic_stringbuf& __rhs)
146      {
147	__xfer_bufptrs __l_st{*this, std::__addressof(__rhs)};
148	__xfer_bufptrs __r_st{__rhs, this};
149	__streambuf_type& __base = __rhs;
150	__streambuf_type::swap(__base);
151	__rhs.pubimbue(this->pubimbue(__rhs.getloc()));
152	std::swap(_M_mode, __rhs._M_mode);
153	std::swap(_M_string, __rhs._M_string);
154      }
155#endif
156
157      // Get and set:
158      /**
159       *  @brief  Copying out the string buffer.
160       *  @return  A copy of one of the underlying sequences.
161       *
162       *  <em>If the buffer is only created in input mode, the underlying
163       *  character sequence is equal to the input sequence; otherwise, it
164       *  is equal to the output sequence.</em> [27.7.1.2]/1
165      */
166      __string_type
167      str() const
168      {
169	__string_type __ret(_M_string.get_allocator());
170	if (this->pptr())
171	  {
172	    // The current egptr() may not be the actual string end.
173	    if (this->pptr() > this->egptr())
174	      __ret.assign(this->pbase(), this->pptr());
175	    else
176	      __ret.assign(this->pbase(), this->egptr());
177	  }
178	else
179	  __ret = _M_string;
180	return __ret;
181      }
182
183      /**
184       *  @brief  Setting a new buffer.
185       *  @param  __s  The string to use as a new sequence.
186       *
187       *  Deallocates any previous stored sequence, then copies @a s to
188       *  use as a new one.
189      */
190      void
191      str(const __string_type& __s)
192      {
193	// Cannot use _M_string = __s, since v3 strings are COW
194	// (not always true now but assign() always works).
195	_M_string.assign(__s.data(), __s.size());
196	_M_stringbuf_init(_M_mode);
197      }
198
199    protected:
200      // Common initialization code goes here.
201      void
202      _M_stringbuf_init(ios_base::openmode __mode)
203      {
204	_M_mode = __mode;
205	__size_type __len = 0;
206	if (_M_mode & (ios_base::ate | ios_base::app))
207	  __len = _M_string.size();
208	_M_sync(const_cast<char_type*>(_M_string.data()), 0, __len);
209      }
210
211      virtual streamsize
212      showmanyc()
213      {
214	streamsize __ret = -1;
215	if (_M_mode & ios_base::in)
216	  {
217	    _M_update_egptr();
218	    __ret = this->egptr() - this->gptr();
219	  }
220	return __ret;
221      }
222
223      virtual int_type
224      underflow();
225
226      virtual int_type
227      pbackfail(int_type __c = traits_type::eof());
228
229      virtual int_type
230      overflow(int_type __c = traits_type::eof());
231
232      /**
233       *  @brief  Manipulates the buffer.
234       *  @param  __s  Pointer to a buffer area.
235       *  @param  __n  Size of @a __s.
236       *  @return  @c this
237       *
238       *  If no buffer has already been created, and both @a __s and @a __n are
239       *  non-zero, then @c __s is used as a buffer; see
240       *  https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering
241       *  for more.
242      */
243      virtual __streambuf_type*
244      setbuf(char_type* __s, streamsize __n)
245      {
246	if (__s && __n >= 0)
247	  {
248	    // This is implementation-defined behavior, and assumes
249	    // that an external char_type array of length __n exists
250	    // and has been pre-allocated. If this is not the case,
251	    // things will quickly blow up.
252
253	    // Step 1: Destroy the current internal array.
254	    _M_string.clear();
255
256	    // Step 2: Use the external array.
257	    _M_sync(__s, __n, 0);
258	  }
259	return this;
260      }
261
262      virtual pos_type
263      seekoff(off_type __off, ios_base::seekdir __way,
264	      ios_base::openmode __mode = ios_base::in | ios_base::out);
265
266      virtual pos_type
267      seekpos(pos_type __sp,
268	      ios_base::openmode __mode = ios_base::in | ios_base::out);
269
270      // Internal function for correctly updating the internal buffer
271      // for a particular _M_string, due to initialization or re-sizing
272      // of an existing _M_string.
273      void
274      _M_sync(char_type* __base, __size_type __i, __size_type __o);
275
276      // Internal function for correctly updating egptr() to the actual
277      // string end.
278      void
279      _M_update_egptr()
280      {
281	const bool __testin = _M_mode & ios_base::in;
282	if (this->pptr() && this->pptr() > this->egptr())
283	  {
284	    if (__testin)
285	      this->setg(this->eback(), this->gptr(), this->pptr());
286	    else
287	      this->setg(this->pptr(), this->pptr(), this->pptr());
288	  }
289      }
290
291      // Works around the issue with pbump, part of the protected
292      // interface of basic_streambuf, taking just an int.
293      void
294      _M_pbump(char_type* __pbeg, char_type* __pend, off_type __off);
295
296    private:
297#if __cplusplus >= 201103L
298#if _GLIBCXX_USE_CXX11_ABI
299      // This type captures the state of the gptr / pptr pointers as offsets
300      // so they can be restored in another object after moving the string.
301      struct __xfer_bufptrs
302      {
303	__xfer_bufptrs(const basic_stringbuf& __from, basic_stringbuf* __to)
304	: _M_to{__to}, _M_goff{-1, -1, -1}, _M_poff{-1, -1, -1}
305	{
306	  const _CharT* const __str = __from._M_string.data();
307	  const _CharT* __end = nullptr;
308	  if (__from.eback())
309	    {
310	      _M_goff[0] = __from.eback() - __str;
311	      _M_goff[1] = __from.gptr() - __str;
312	      _M_goff[2] = __from.egptr() - __str;
313	      __end = __from.egptr();
314	    }
315	  if (__from.pbase())
316	    {
317	      _M_poff[0] = __from.pbase() - __str;
318	      _M_poff[1] = __from.pptr() - __from.pbase();
319	      _M_poff[2] = __from.epptr() - __str;
320	      if (__from.pptr() > __end)
321		__end = __from.pptr();
322	    }
323
324	  // Set _M_string length to the greater of the get and put areas.
325	  if (__end)
326	    {
327	      // The const_cast avoids changing this constructor's signature,
328	      // because it is exported from the dynamic library.
329	      auto& __mut_from = const_cast<basic_stringbuf&>(__from);
330	      __mut_from._M_string._M_length(__end - __str);
331	    }
332	}
333
334	~__xfer_bufptrs()
335	{
336	  char_type* __str = const_cast<char_type*>(_M_to->_M_string.data());
337	  if (_M_goff[0] != -1)
338	    _M_to->setg(__str+_M_goff[0], __str+_M_goff[1], __str+_M_goff[2]);
339	  if (_M_poff[0] != -1)
340	    _M_to->_M_pbump(__str+_M_poff[0], __str+_M_poff[2], _M_poff[1]);
341	}
342
343	basic_stringbuf* _M_to;
344	off_type _M_goff[3];
345	off_type _M_poff[3];
346      };
347#else
348      // This type does nothing when using Copy-On-Write strings.
349      struct __xfer_bufptrs
350      {
351	__xfer_bufptrs(const basic_stringbuf&, basic_stringbuf*) { }
352      };
353#endif
354
355      // The move constructor initializes an __xfer_bufptrs temporary then
356      // delegates to this constructor to performs moves during its lifetime.
357      basic_stringbuf(basic_stringbuf&& __rhs, __xfer_bufptrs&&)
358      : __streambuf_type(static_cast<const __streambuf_type&>(__rhs)),
359      _M_mode(__rhs._M_mode), _M_string(std::move(__rhs._M_string))
360      { }
361#endif
362    };
363
364
365  // [27.7.2] Template class basic_istringstream
366  /**
367   *  @brief  Controlling input for std::string.
368   *  @ingroup io
369   *
370   *  @tparam _CharT  Type of character stream.
371   *  @tparam _Traits  Traits for character type, defaults to
372   *                   char_traits<_CharT>.
373   *  @tparam _Alloc  Allocator type, defaults to allocator<_CharT>.
374   *
375   *  This class supports reading from objects of type std::basic_string,
376   *  using the inherited functions from std::basic_istream.  To control
377   *  the associated sequence, an instance of std::basic_stringbuf is used,
378   *  which this page refers to as @c sb.
379  */
380  template<typename _CharT, typename _Traits, typename _Alloc>
381    class basic_istringstream : public basic_istream<_CharT, _Traits>
382    {
383    public:
384      // Types:
385      typedef _CharT 					char_type;
386      typedef _Traits 					traits_type;
387      // _GLIBCXX_RESOLVE_LIB_DEFECTS
388      // 251. basic_stringbuf missing allocator_type
389      typedef _Alloc				       	allocator_type;
390      typedef typename traits_type::int_type 		int_type;
391      typedef typename traits_type::pos_type 		pos_type;
392      typedef typename traits_type::off_type 		off_type;
393
394      // Non-standard types:
395      typedef basic_string<_CharT, _Traits, _Alloc> 	__string_type;
396      typedef basic_stringbuf<_CharT, _Traits, _Alloc> 	__stringbuf_type;
397      typedef basic_istream<char_type, traits_type>	__istream_type;
398
399    private:
400      __stringbuf_type	_M_stringbuf;
401
402    public:
403      // Constructors:
404      /**
405       *  @brief  Default constructor starts with an empty string buffer.
406       *  @param  __mode  Whether the buffer can read, or write, or both.
407       *
408       *  @c ios_base::in is automatically included in @a __mode.
409       *
410       *  Initializes @c sb using @c __mode|in, and passes @c &sb to the base
411       *  class initializer.  Does not allocate any buffer.
412       *
413       *  That's a lie.  We initialize the base class with NULL, because the
414       *  string class does its own memory management.
415      */
416      explicit
417      basic_istringstream(ios_base::openmode __mode = ios_base::in)
418      : __istream_type(), _M_stringbuf(__mode | ios_base::in)
419      { this->init(&_M_stringbuf); }
420
421      /**
422       *  @brief  Starts with an existing string buffer.
423       *  @param  __str  A string to copy as a starting buffer.
424       *  @param  __mode  Whether the buffer can read, or write, or both.
425       *
426       *  @c ios_base::in is automatically included in @a mode.
427       *
428       *  Initializes @c sb using @a str and @c mode|in, and passes @c &sb
429       *  to the base class initializer.
430       *
431       *  That's a lie.  We initialize the base class with NULL, because the
432       *  string class does its own memory management.
433      */
434      explicit
435      basic_istringstream(const __string_type& __str,
436			  ios_base::openmode __mode = ios_base::in)
437      : __istream_type(), _M_stringbuf(__str, __mode | ios_base::in)
438      { this->init(&_M_stringbuf); }
439
440      /**
441       *  @brief  The destructor does nothing.
442       *
443       *  The buffer is deallocated by the stringbuf object, not the
444       *  formatting stream.
445      */
446      ~basic_istringstream()
447      { }
448
449#if __cplusplus >= 201103L
450      basic_istringstream(const basic_istringstream&) = delete;
451
452      basic_istringstream(basic_istringstream&& __rhs)
453      : __istream_type(std::move(__rhs)),
454      _M_stringbuf(std::move(__rhs._M_stringbuf))
455      { __istream_type::set_rdbuf(&_M_stringbuf); }
456
457      // 27.8.3.2 Assign and swap:
458
459      basic_istringstream&
460      operator=(const basic_istringstream&) = delete;
461
462      basic_istringstream&
463      operator=(basic_istringstream&& __rhs)
464      {
465	__istream_type::operator=(std::move(__rhs));
466	_M_stringbuf = std::move(__rhs._M_stringbuf);
467	return *this;
468      }
469
470      void
471      swap(basic_istringstream& __rhs)
472      {
473	__istream_type::swap(__rhs);
474	_M_stringbuf.swap(__rhs._M_stringbuf);
475      }
476#endif
477
478      // Members:
479      /**
480       *  @brief  Accessing the underlying buffer.
481       *  @return  The current basic_stringbuf buffer.
482       *
483       *  This hides both signatures of std::basic_ios::rdbuf().
484      */
485      __stringbuf_type*
486      rdbuf() const
487      { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
488
489      /**
490       *  @brief  Copying out the string buffer.
491       *  @return  @c rdbuf()->str()
492      */
493      __string_type
494      str() const
495      { return _M_stringbuf.str(); }
496
497      /**
498       *  @brief  Setting a new buffer.
499       *  @param  __s  The string to use as a new sequence.
500       *
501       *  Calls @c rdbuf()->str(s).
502      */
503      void
504      str(const __string_type& __s)
505      { _M_stringbuf.str(__s); }
506    };
507
508
509  // [27.7.3] Template class basic_ostringstream
510  /**
511   *  @brief  Controlling output for std::string.
512   *  @ingroup io
513   *
514   *  @tparam _CharT  Type of character stream.
515   *  @tparam _Traits  Traits for character type, defaults to
516   *                   char_traits<_CharT>.
517   *  @tparam _Alloc  Allocator type, defaults to allocator<_CharT>.
518   *
519   *  This class supports writing to objects of type std::basic_string,
520   *  using the inherited functions from std::basic_ostream.  To control
521   *  the associated sequence, an instance of std::basic_stringbuf is used,
522   *  which this page refers to as @c sb.
523  */
524  template <typename _CharT, typename _Traits, typename _Alloc>
525    class basic_ostringstream : public basic_ostream<_CharT, _Traits>
526    {
527    public:
528      // Types:
529      typedef _CharT 					char_type;
530      typedef _Traits 					traits_type;
531      // _GLIBCXX_RESOLVE_LIB_DEFECTS
532      // 251. basic_stringbuf missing allocator_type
533      typedef _Alloc				       	allocator_type;
534      typedef typename traits_type::int_type 		int_type;
535      typedef typename traits_type::pos_type 		pos_type;
536      typedef typename traits_type::off_type 		off_type;
537
538      // Non-standard types:
539      typedef basic_string<_CharT, _Traits, _Alloc> 	__string_type;
540      typedef basic_stringbuf<_CharT, _Traits, _Alloc> 	__stringbuf_type;
541      typedef basic_ostream<char_type, traits_type>	__ostream_type;
542
543    private:
544      __stringbuf_type	_M_stringbuf;
545
546    public:
547      // Constructors/destructor:
548      /**
549       *  @brief  Default constructor starts with an empty string buffer.
550       *  @param  __mode  Whether the buffer can read, or write, or both.
551       *
552       *  @c ios_base::out is automatically included in @a mode.
553       *
554       *  Initializes @c sb using @c mode|out, and passes @c &sb to the base
555       *  class initializer.  Does not allocate any buffer.
556       *
557       *  That's a lie.  We initialize the base class with NULL, because the
558       *  string class does its own memory management.
559      */
560      explicit
561      basic_ostringstream(ios_base::openmode __mode = ios_base::out)
562      : __ostream_type(), _M_stringbuf(__mode | ios_base::out)
563      { this->init(&_M_stringbuf); }
564
565      /**
566       *  @brief  Starts with an existing string buffer.
567       *  @param  __str  A string to copy as a starting buffer.
568       *  @param  __mode  Whether the buffer can read, or write, or both.
569       *
570       *  @c ios_base::out is automatically included in @a mode.
571       *
572       *  Initializes @c sb using @a str and @c mode|out, and passes @c &sb
573       *  to the base class initializer.
574       *
575       *  That's a lie.  We initialize the base class with NULL, because the
576       *  string class does its own memory management.
577      */
578      explicit
579      basic_ostringstream(const __string_type& __str,
580			  ios_base::openmode __mode = ios_base::out)
581      : __ostream_type(), _M_stringbuf(__str, __mode | ios_base::out)
582      { this->init(&_M_stringbuf); }
583
584      /**
585       *  @brief  The destructor does nothing.
586       *
587       *  The buffer is deallocated by the stringbuf object, not the
588       *  formatting stream.
589      */
590      ~basic_ostringstream()
591      { }
592
593#if __cplusplus >= 201103L
594      basic_ostringstream(const basic_ostringstream&) = delete;
595
596      basic_ostringstream(basic_ostringstream&& __rhs)
597      : __ostream_type(std::move(__rhs)),
598      _M_stringbuf(std::move(__rhs._M_stringbuf))
599      { __ostream_type::set_rdbuf(&_M_stringbuf); }
600
601      // 27.8.3.2 Assign and swap:
602
603      basic_ostringstream&
604      operator=(const basic_ostringstream&) = delete;
605
606      basic_ostringstream&
607      operator=(basic_ostringstream&& __rhs)
608      {
609	__ostream_type::operator=(std::move(__rhs));
610	_M_stringbuf = std::move(__rhs._M_stringbuf);
611	return *this;
612      }
613
614      void
615      swap(basic_ostringstream& __rhs)
616      {
617	__ostream_type::swap(__rhs);
618	_M_stringbuf.swap(__rhs._M_stringbuf);
619      }
620#endif
621
622      // Members:
623      /**
624       *  @brief  Accessing the underlying buffer.
625       *  @return  The current basic_stringbuf buffer.
626       *
627       *  This hides both signatures of std::basic_ios::rdbuf().
628      */
629      __stringbuf_type*
630      rdbuf() const
631      { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
632
633      /**
634       *  @brief  Copying out the string buffer.
635       *  @return  @c rdbuf()->str()
636      */
637      __string_type
638      str() const
639      { return _M_stringbuf.str(); }
640
641      /**
642       *  @brief  Setting a new buffer.
643       *  @param  __s  The string to use as a new sequence.
644       *
645       *  Calls @c rdbuf()->str(s).
646      */
647      void
648      str(const __string_type& __s)
649      { _M_stringbuf.str(__s); }
650    };
651
652
653  // [27.7.4] Template class basic_stringstream
654  /**
655   *  @brief  Controlling input and output for std::string.
656   *  @ingroup io
657   *
658   *  @tparam _CharT  Type of character stream.
659   *  @tparam _Traits  Traits for character type, defaults to
660   *                   char_traits<_CharT>.
661   *  @tparam _Alloc  Allocator type, defaults to allocator<_CharT>.
662   *
663   *  This class supports reading from and writing to objects of type
664   *  std::basic_string, using the inherited functions from
665   *  std::basic_iostream.  To control the associated sequence, an instance
666   *  of std::basic_stringbuf is used, which this page refers to as @c sb.
667  */
668  template <typename _CharT, typename _Traits, typename _Alloc>
669    class basic_stringstream : public basic_iostream<_CharT, _Traits>
670    {
671    public:
672      // Types:
673      typedef _CharT 					char_type;
674      typedef _Traits 					traits_type;
675      // _GLIBCXX_RESOLVE_LIB_DEFECTS
676      // 251. basic_stringbuf missing allocator_type
677      typedef _Alloc				       	allocator_type;
678      typedef typename traits_type::int_type 		int_type;
679      typedef typename traits_type::pos_type 		pos_type;
680      typedef typename traits_type::off_type 		off_type;
681
682      // Non-standard Types:
683      typedef basic_string<_CharT, _Traits, _Alloc> 	__string_type;
684      typedef basic_stringbuf<_CharT, _Traits, _Alloc> 	__stringbuf_type;
685      typedef basic_iostream<char_type, traits_type>	__iostream_type;
686
687    private:
688      __stringbuf_type	_M_stringbuf;
689
690    public:
691      // Constructors/destructors
692      /**
693       *  @brief  Default constructor starts with an empty string buffer.
694       *  @param  __m  Whether the buffer can read, or write, or both.
695       *
696       *  Initializes @c sb using the mode from @c __m, and passes @c
697       *  &sb to the base class initializer.  Does not allocate any
698       *  buffer.
699       *
700       *  That's a lie.  We initialize the base class with NULL, because the
701       *  string class does its own memory management.
702      */
703      explicit
704      basic_stringstream(ios_base::openmode __m = ios_base::out | ios_base::in)
705      : __iostream_type(), _M_stringbuf(__m)
706      { this->init(&_M_stringbuf); }
707
708      /**
709       *  @brief  Starts with an existing string buffer.
710       *  @param  __str  A string to copy as a starting buffer.
711       *  @param  __m  Whether the buffer can read, or write, or both.
712       *
713       *  Initializes @c sb using @a __str and @c __m, and passes @c &sb
714       *  to the base class initializer.
715       *
716       *  That's a lie.  We initialize the base class with NULL, because the
717       *  string class does its own memory management.
718      */
719      explicit
720      basic_stringstream(const __string_type& __str,
721			 ios_base::openmode __m = ios_base::out | ios_base::in)
722      : __iostream_type(), _M_stringbuf(__str, __m)
723      { this->init(&_M_stringbuf); }
724
725      /**
726       *  @brief  The destructor does nothing.
727       *
728       *  The buffer is deallocated by the stringbuf object, not the
729       *  formatting stream.
730      */
731      ~basic_stringstream()
732      { }
733
734#if __cplusplus >= 201103L
735      basic_stringstream(const basic_stringstream&) = delete;
736
737      basic_stringstream(basic_stringstream&& __rhs)
738      : __iostream_type(std::move(__rhs)),
739      _M_stringbuf(std::move(__rhs._M_stringbuf))
740      { __iostream_type::set_rdbuf(&_M_stringbuf); }
741
742      // 27.8.3.2 Assign and swap:
743
744      basic_stringstream&
745      operator=(const basic_stringstream&) = delete;
746
747      basic_stringstream&
748      operator=(basic_stringstream&& __rhs)
749      {
750	__iostream_type::operator=(std::move(__rhs));
751	_M_stringbuf = std::move(__rhs._M_stringbuf);
752	return *this;
753      }
754
755      void
756      swap(basic_stringstream& __rhs)
757      {
758	__iostream_type::swap(__rhs);
759	_M_stringbuf.swap(__rhs._M_stringbuf);
760      }
761#endif
762
763      // Members:
764      /**
765       *  @brief  Accessing the underlying buffer.
766       *  @return  The current basic_stringbuf buffer.
767       *
768       *  This hides both signatures of std::basic_ios::rdbuf().
769      */
770      __stringbuf_type*
771      rdbuf() const
772      { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
773
774      /**
775       *  @brief  Copying out the string buffer.
776       *  @return  @c rdbuf()->str()
777      */
778      __string_type
779      str() const
780      { return _M_stringbuf.str(); }
781
782      /**
783       *  @brief  Setting a new buffer.
784       *  @param  __s  The string to use as a new sequence.
785       *
786       *  Calls @c rdbuf()->str(s).
787      */
788      void
789      str(const __string_type& __s)
790      { _M_stringbuf.str(__s); }
791    };
792
793#if __cplusplus >= 201103L
794  /// Swap specialization for stringbufs.
795  template <class _CharT, class _Traits, class _Allocator>
796    inline void
797    swap(basic_stringbuf<_CharT, _Traits, _Allocator>& __x,
798	 basic_stringbuf<_CharT, _Traits, _Allocator>& __y)
799    { __x.swap(__y); }
800
801  /// Swap specialization for istringstreams.
802  template <class _CharT, class _Traits, class _Allocator>
803    inline void
804    swap(basic_istringstream<_CharT, _Traits, _Allocator>& __x,
805	 basic_istringstream<_CharT, _Traits, _Allocator>& __y)
806    { __x.swap(__y); }
807
808  /// Swap specialization for ostringstreams.
809  template <class _CharT, class _Traits, class _Allocator>
810    inline void
811    swap(basic_ostringstream<_CharT, _Traits, _Allocator>& __x,
812	 basic_ostringstream<_CharT, _Traits, _Allocator>& __y)
813    { __x.swap(__y); }
814
815  /// Swap specialization for stringstreams.
816  template <class _CharT, class _Traits, class _Allocator>
817    inline void
818    swap(basic_stringstream<_CharT, _Traits, _Allocator>& __x,
819	 basic_stringstream<_CharT, _Traits, _Allocator>& __y)
820    { __x.swap(__y); }
821#endif
822
823_GLIBCXX_END_NAMESPACE_CXX11
824_GLIBCXX_END_NAMESPACE_VERSION
825} // namespace
826
827#include <bits/sstream.tcc>
828
829#endif /* _GLIBCXX_SSTREAM */
830