1// String based streams -*- C++ -*-
2
3// Copyright (C) 1997-2017 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(), _M_string(__str.data(), __str.size())
116      { _M_stringbuf_init(__mode); }
117
118#if __cplusplus >= 201103L
119      basic_stringbuf(const basic_stringbuf&) = delete;
120
121      basic_stringbuf(basic_stringbuf&& __rhs)
122      : basic_stringbuf(std::move(__rhs), __xfer_bufptrs(__rhs, this))
123      { __rhs._M_sync(const_cast<char_type*>(__rhs._M_string.data()), 0, 0); }
124
125      // 27.8.2.2 Assign and swap:
126
127      basic_stringbuf&
128      operator=(const basic_stringbuf&) = delete;
129
130      basic_stringbuf&
131      operator=(basic_stringbuf&& __rhs)
132      {
133	__xfer_bufptrs __st{__rhs, this};
134	const __streambuf_type& __base = __rhs;
135	__streambuf_type::operator=(__base);
136	this->pubimbue(__rhs.getloc());
137	_M_mode = __rhs._M_mode;
138	_M_string = std::move(__rhs._M_string);
139	__rhs._M_sync(const_cast<char_type*>(__rhs._M_string.data()), 0, 0);
140	return *this;
141      }
142
143      void
144      swap(basic_stringbuf& __rhs)
145      {
146	__xfer_bufptrs __l_st{*this, std::__addressof(__rhs)};
147	__xfer_bufptrs __r_st{__rhs, this};
148	__streambuf_type& __base = __rhs;
149	__streambuf_type::swap(__base);
150	__rhs.pubimbue(this->pubimbue(__rhs.getloc()));
151	std::swap(_M_mode, __rhs._M_mode);
152	std::swap(_M_string, __rhs._M_string);
153      }
154#endif
155
156      // Get and set:
157      /**
158       *  @brief  Copying out the string buffer.
159       *  @return  A copy of one of the underlying sequences.
160       *
161       *  <em>If the buffer is only created in input mode, the underlying
162       *  character sequence is equal to the input sequence; otherwise, it
163       *  is equal to the output sequence.</em> [27.7.1.2]/1
164      */
165      __string_type
166      str() const
167      {
168	__string_type __ret;
169	if (this->pptr())
170	  {
171	    // The current egptr() may not be the actual string end.
172	    if (this->pptr() > this->egptr())
173	      __ret = __string_type(this->pbase(), this->pptr());
174	    else
175 	      __ret = __string_type(this->pbase(), this->egptr());
176	  }
177	else
178	  __ret = _M_string;
179	return __ret;
180      }
181
182      /**
183       *  @brief  Setting a new buffer.
184       *  @param  __s  The string to use as a new sequence.
185       *
186       *  Deallocates any previous stored sequence, then copies @a s to
187       *  use as a new one.
188      */
189      void
190      str(const __string_type& __s)
191      {
192	// Cannot use _M_string = __s, since v3 strings are COW
193	// (not always true now but assign() always works).
194	_M_string.assign(__s.data(), __s.size());
195	_M_stringbuf_init(_M_mode);
196      }
197
198    protected:
199      // Common initialization code goes here.
200      void
201      _M_stringbuf_init(ios_base::openmode __mode)
202      {
203	_M_mode = __mode;
204	__size_type __len = 0;
205	if (_M_mode & (ios_base::ate | ios_base::app))
206	  __len = _M_string.size();
207	_M_sync(const_cast<char_type*>(_M_string.data()), 0, __len);
208      }
209
210      virtual streamsize
211      showmanyc()
212      {
213	streamsize __ret = -1;
214	if (_M_mode & ios_base::in)
215	  {
216	    _M_update_egptr();
217	    __ret = this->egptr() - this->gptr();
218	  }
219	return __ret;
220      }
221
222      virtual int_type
223      underflow();
224
225      virtual int_type
226      pbackfail(int_type __c = traits_type::eof());
227
228      virtual int_type
229      overflow(int_type __c = traits_type::eof());
230
231      /**
232       *  @brief  Manipulates the buffer.
233       *  @param  __s  Pointer to a buffer area.
234       *  @param  __n  Size of @a __s.
235       *  @return  @c this
236       *
237       *  If no buffer has already been created, and both @a __s and @a __n are
238       *  non-zero, then @c __s is used as a buffer; see
239       *  https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering
240       *  for more.
241      */
242      virtual __streambuf_type*
243      setbuf(char_type* __s, streamsize __n)
244      {
245	if (__s && __n >= 0)
246	  {
247	    // This is implementation-defined behavior, and assumes
248	    // that an external char_type array of length __n exists
249	    // and has been pre-allocated. If this is not the case,
250	    // things will quickly blow up.
251
252	    // Step 1: Destroy the current internal array.
253	    _M_string.clear();
254
255	    // Step 2: Use the external array.
256	    _M_sync(__s, __n, 0);
257	  }
258	return this;
259      }
260
261      virtual pos_type
262      seekoff(off_type __off, ios_base::seekdir __way,
263	      ios_base::openmode __mode = ios_base::in | ios_base::out);
264
265      virtual pos_type
266      seekpos(pos_type __sp,
267	      ios_base::openmode __mode = ios_base::in | ios_base::out);
268
269      // Internal function for correctly updating the internal buffer
270      // for a particular _M_string, due to initialization or re-sizing
271      // of an existing _M_string.
272      void
273      _M_sync(char_type* __base, __size_type __i, __size_type __o);
274
275      // Internal function for correctly updating egptr() to the actual
276      // string end.
277      void
278      _M_update_egptr()
279      {
280	const bool __testin = _M_mode & ios_base::in;
281	if (this->pptr() && this->pptr() > this->egptr())
282	  {
283	    if (__testin)
284	      this->setg(this->eback(), this->gptr(), this->pptr());
285	    else
286	      this->setg(this->pptr(), this->pptr(), this->pptr());
287	  }
288      }
289
290      // Works around the issue with pbump, part of the protected
291      // interface of basic_streambuf, taking just an int.
292      void
293      _M_pbump(char_type* __pbeg, char_type* __pend, off_type __off);
294
295    private:
296#if __cplusplus >= 201103L
297#if _GLIBCXX_USE_CXX11_ABI
298      // This type captures the state of the gptr / pptr pointers as offsets
299      // so they can be restored in another object after moving the string.
300      struct __xfer_bufptrs
301      {
302	__xfer_bufptrs(const basic_stringbuf& __from, basic_stringbuf* __to)
303	: _M_to{__to}, _M_goff{-1, -1, -1}, _M_poff{-1, -1, -1}
304	{
305	  const _CharT* const __str = __from._M_string.data();
306	  const _CharT* __end = nullptr;
307	  if (__from.eback())
308	    {
309	      _M_goff[0] = __from.eback() - __str;
310	      _M_goff[1] = __from.gptr() - __str;
311	      _M_goff[2] = __from.egptr() - __str;
312	      __end = __from.egptr();
313	    }
314	  if (__from.pbase())
315	    {
316	      _M_poff[0] = __from.pbase() - __str;
317	      _M_poff[1] = __from.pptr() - __from.pbase();
318	      _M_poff[2] = __from.epptr() - __str;
319	      if (__from.pptr() > __end)
320		__end = __from.pptr();
321	    }
322
323	  // Set _M_string length to the greater of the get and put areas.
324	  if (__end)
325	    {
326	      // The const_cast avoids changing this constructor's signature,
327	      // because it is exported from the dynamic library.
328	      auto& __mut_from = const_cast<basic_stringbuf&>(__from);
329	      __mut_from._M_string._M_length(__end - __str);
330	    }
331	}
332
333	~__xfer_bufptrs()
334	{
335	  char_type* __str = const_cast<char_type*>(_M_to->_M_string.data());
336	  if (_M_goff[0] != -1)
337	    _M_to->setg(__str+_M_goff[0], __str+_M_goff[1], __str+_M_goff[2]);
338	  if (_M_poff[0] != -1)
339	    _M_to->_M_pbump(__str+_M_poff[0], __str+_M_poff[2], _M_poff[1]);
340	}
341
342	basic_stringbuf* _M_to;
343	off_type _M_goff[3];
344	off_type _M_poff[3];
345      };
346#else
347      // This type does nothing when using Copy-On-Write strings.
348      struct __xfer_bufptrs
349      {
350	__xfer_bufptrs(const basic_stringbuf&, basic_stringbuf*) { }
351      };
352#endif
353
354      // The move constructor initializes an __xfer_bufptrs temporary then
355      // delegates to this constructor to performs moves during its lifetime.
356      basic_stringbuf(basic_stringbuf&& __rhs, __xfer_bufptrs&&)
357      : __streambuf_type(static_cast<const __streambuf_type&>(__rhs)),
358      _M_mode(__rhs._M_mode), _M_string(std::move(__rhs._M_string))
359      { }
360#endif
361    };
362
363
364  // [27.7.2] Template class basic_istringstream
365  /**
366   *  @brief  Controlling input for std::string.
367   *  @ingroup io
368   *
369   *  @tparam _CharT  Type of character stream.
370   *  @tparam _Traits  Traits for character type, defaults to
371   *                   char_traits<_CharT>.
372   *  @tparam _Alloc  Allocator type, defaults to allocator<_CharT>.
373   *
374   *  This class supports reading from objects of type std::basic_string,
375   *  using the inherited functions from std::basic_istream.  To control
376   *  the associated sequence, an instance of std::basic_stringbuf is used,
377   *  which this page refers to as @c sb.
378  */
379  template<typename _CharT, typename _Traits, typename _Alloc>
380    class basic_istringstream : public basic_istream<_CharT, _Traits>
381    {
382    public:
383      // Types:
384      typedef _CharT 					char_type;
385      typedef _Traits 					traits_type;
386      // _GLIBCXX_RESOLVE_LIB_DEFECTS
387      // 251. basic_stringbuf missing allocator_type
388      typedef _Alloc				       	allocator_type;
389      typedef typename traits_type::int_type 		int_type;
390      typedef typename traits_type::pos_type 		pos_type;
391      typedef typename traits_type::off_type 		off_type;
392
393      // Non-standard types:
394      typedef basic_string<_CharT, _Traits, _Alloc> 	__string_type;
395      typedef basic_stringbuf<_CharT, _Traits, _Alloc> 	__stringbuf_type;
396      typedef basic_istream<char_type, traits_type>	__istream_type;
397
398    private:
399      __stringbuf_type	_M_stringbuf;
400
401    public:
402      // Constructors:
403      /**
404       *  @brief  Default constructor starts with an empty string buffer.
405       *  @param  __mode  Whether the buffer can read, or write, or both.
406       *
407       *  @c ios_base::in is automatically included in @a __mode.
408       *
409       *  Initializes @c sb using @c __mode|in, and passes @c &sb to the base
410       *  class initializer.  Does not allocate any buffer.
411       *
412       *  That's a lie.  We initialize the base class with NULL, because the
413       *  string class does its own memory management.
414      */
415      explicit
416      basic_istringstream(ios_base::openmode __mode = ios_base::in)
417      : __istream_type(), _M_stringbuf(__mode | ios_base::in)
418      { this->init(&_M_stringbuf); }
419
420      /**
421       *  @brief  Starts with an existing string buffer.
422       *  @param  __str  A string to copy as a starting buffer.
423       *  @param  __mode  Whether the buffer can read, or write, or both.
424       *
425       *  @c ios_base::in is automatically included in @a mode.
426       *
427       *  Initializes @c sb using @a str and @c mode|in, and passes @c &sb
428       *  to the base class initializer.
429       *
430       *  That's a lie.  We initialize the base class with NULL, because the
431       *  string class does its own memory management.
432      */
433      explicit
434      basic_istringstream(const __string_type& __str,
435			  ios_base::openmode __mode = ios_base::in)
436      : __istream_type(), _M_stringbuf(__str, __mode | ios_base::in)
437      { this->init(&_M_stringbuf); }
438
439      /**
440       *  @brief  The destructor does nothing.
441       *
442       *  The buffer is deallocated by the stringbuf object, not the
443       *  formatting stream.
444      */
445      ~basic_istringstream()
446      { }
447
448#if __cplusplus >= 201103L
449      basic_istringstream(const basic_istringstream&) = delete;
450
451      basic_istringstream(basic_istringstream&& __rhs)
452      : __istream_type(std::move(__rhs)),
453      _M_stringbuf(std::move(__rhs._M_stringbuf))
454      { __istream_type::set_rdbuf(&_M_stringbuf); }
455
456      // 27.8.3.2 Assign and swap:
457
458      basic_istringstream&
459      operator=(const basic_istringstream&) = delete;
460
461      basic_istringstream&
462      operator=(basic_istringstream&& __rhs)
463      {
464	__istream_type::operator=(std::move(__rhs));
465	_M_stringbuf = std::move(__rhs._M_stringbuf);
466	return *this;
467      }
468
469      void
470      swap(basic_istringstream& __rhs)
471      {
472	__istream_type::swap(__rhs);
473	_M_stringbuf.swap(__rhs._M_stringbuf);
474      }
475#endif
476
477      // Members:
478      /**
479       *  @brief  Accessing the underlying buffer.
480       *  @return  The current basic_stringbuf buffer.
481       *
482       *  This hides both signatures of std::basic_ios::rdbuf().
483      */
484      __stringbuf_type*
485      rdbuf() const
486      { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
487
488      /**
489       *  @brief  Copying out the string buffer.
490       *  @return  @c rdbuf()->str()
491      */
492      __string_type
493      str() const
494      { return _M_stringbuf.str(); }
495
496      /**
497       *  @brief  Setting a new buffer.
498       *  @param  __s  The string to use as a new sequence.
499       *
500       *  Calls @c rdbuf()->str(s).
501      */
502      void
503      str(const __string_type& __s)
504      { _M_stringbuf.str(__s); }
505    };
506
507
508  // [27.7.3] Template class basic_ostringstream
509  /**
510   *  @brief  Controlling output for std::string.
511   *  @ingroup io
512   *
513   *  @tparam _CharT  Type of character stream.
514   *  @tparam _Traits  Traits for character type, defaults to
515   *                   char_traits<_CharT>.
516   *  @tparam _Alloc  Allocator type, defaults to allocator<_CharT>.
517   *
518   *  This class supports writing to objects of type std::basic_string,
519   *  using the inherited functions from std::basic_ostream.  To control
520   *  the associated sequence, an instance of std::basic_stringbuf is used,
521   *  which this page refers to as @c sb.
522  */
523  template <typename _CharT, typename _Traits, typename _Alloc>
524    class basic_ostringstream : public basic_ostream<_CharT, _Traits>
525    {
526    public:
527      // Types:
528      typedef _CharT 					char_type;
529      typedef _Traits 					traits_type;
530      // _GLIBCXX_RESOLVE_LIB_DEFECTS
531      // 251. basic_stringbuf missing allocator_type
532      typedef _Alloc				       	allocator_type;
533      typedef typename traits_type::int_type 		int_type;
534      typedef typename traits_type::pos_type 		pos_type;
535      typedef typename traits_type::off_type 		off_type;
536
537      // Non-standard types:
538      typedef basic_string<_CharT, _Traits, _Alloc> 	__string_type;
539      typedef basic_stringbuf<_CharT, _Traits, _Alloc> 	__stringbuf_type;
540      typedef basic_ostream<char_type, traits_type>	__ostream_type;
541
542    private:
543      __stringbuf_type	_M_stringbuf;
544
545    public:
546      // Constructors/destructor:
547      /**
548       *  @brief  Default constructor starts with an empty string buffer.
549       *  @param  __mode  Whether the buffer can read, or write, or both.
550       *
551       *  @c ios_base::out is automatically included in @a mode.
552       *
553       *  Initializes @c sb using @c mode|out, and passes @c &sb to the base
554       *  class initializer.  Does not allocate any buffer.
555       *
556       *  That's a lie.  We initialize the base class with NULL, because the
557       *  string class does its own memory management.
558      */
559      explicit
560      basic_ostringstream(ios_base::openmode __mode = ios_base::out)
561      : __ostream_type(), _M_stringbuf(__mode | ios_base::out)
562      { this->init(&_M_stringbuf); }
563
564      /**
565       *  @brief  Starts with an existing string buffer.
566       *  @param  __str  A string to copy as a starting buffer.
567       *  @param  __mode  Whether the buffer can read, or write, or both.
568       *
569       *  @c ios_base::out is automatically included in @a mode.
570       *
571       *  Initializes @c sb using @a str and @c mode|out, and passes @c &sb
572       *  to the base class initializer.
573       *
574       *  That's a lie.  We initialize the base class with NULL, because the
575       *  string class does its own memory management.
576      */
577      explicit
578      basic_ostringstream(const __string_type& __str,
579			  ios_base::openmode __mode = ios_base::out)
580      : __ostream_type(), _M_stringbuf(__str, __mode | ios_base::out)
581      { this->init(&_M_stringbuf); }
582
583      /**
584       *  @brief  The destructor does nothing.
585       *
586       *  The buffer is deallocated by the stringbuf object, not the
587       *  formatting stream.
588      */
589      ~basic_ostringstream()
590      { }
591
592#if __cplusplus >= 201103L
593      basic_ostringstream(const basic_ostringstream&) = delete;
594
595      basic_ostringstream(basic_ostringstream&& __rhs)
596      : __ostream_type(std::move(__rhs)),
597      _M_stringbuf(std::move(__rhs._M_stringbuf))
598      { __ostream_type::set_rdbuf(&_M_stringbuf); }
599
600      // 27.8.3.2 Assign and swap:
601
602      basic_ostringstream&
603      operator=(const basic_ostringstream&) = delete;
604
605      basic_ostringstream&
606      operator=(basic_ostringstream&& __rhs)
607      {
608	__ostream_type::operator=(std::move(__rhs));
609	_M_stringbuf = std::move(__rhs._M_stringbuf);
610	return *this;
611      }
612
613      void
614      swap(basic_ostringstream& __rhs)
615      {
616	__ostream_type::swap(__rhs);
617	_M_stringbuf.swap(__rhs._M_stringbuf);
618      }
619#endif
620
621      // Members:
622      /**
623       *  @brief  Accessing the underlying buffer.
624       *  @return  The current basic_stringbuf buffer.
625       *
626       *  This hides both signatures of std::basic_ios::rdbuf().
627      */
628      __stringbuf_type*
629      rdbuf() const
630      { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
631
632      /**
633       *  @brief  Copying out the string buffer.
634       *  @return  @c rdbuf()->str()
635      */
636      __string_type
637      str() const
638      { return _M_stringbuf.str(); }
639
640      /**
641       *  @brief  Setting a new buffer.
642       *  @param  __s  The string to use as a new sequence.
643       *
644       *  Calls @c rdbuf()->str(s).
645      */
646      void
647      str(const __string_type& __s)
648      { _M_stringbuf.str(__s); }
649    };
650
651
652  // [27.7.4] Template class basic_stringstream
653  /**
654   *  @brief  Controlling input and output for std::string.
655   *  @ingroup io
656   *
657   *  @tparam _CharT  Type of character stream.
658   *  @tparam _Traits  Traits for character type, defaults to
659   *                   char_traits<_CharT>.
660   *  @tparam _Alloc  Allocator type, defaults to allocator<_CharT>.
661   *
662   *  This class supports reading from and writing to objects of type
663   *  std::basic_string, using the inherited functions from
664   *  std::basic_iostream.  To control the associated sequence, an instance
665   *  of std::basic_stringbuf is used, which this page refers to as @c sb.
666  */
667  template <typename _CharT, typename _Traits, typename _Alloc>
668    class basic_stringstream : public basic_iostream<_CharT, _Traits>
669    {
670    public:
671      // Types:
672      typedef _CharT 					char_type;
673      typedef _Traits 					traits_type;
674      // _GLIBCXX_RESOLVE_LIB_DEFECTS
675      // 251. basic_stringbuf missing allocator_type
676      typedef _Alloc				       	allocator_type;
677      typedef typename traits_type::int_type 		int_type;
678      typedef typename traits_type::pos_type 		pos_type;
679      typedef typename traits_type::off_type 		off_type;
680
681      // Non-standard Types:
682      typedef basic_string<_CharT, _Traits, _Alloc> 	__string_type;
683      typedef basic_stringbuf<_CharT, _Traits, _Alloc> 	__stringbuf_type;
684      typedef basic_iostream<char_type, traits_type>	__iostream_type;
685
686    private:
687      __stringbuf_type	_M_stringbuf;
688
689    public:
690      // Constructors/destructors
691      /**
692       *  @brief  Default constructor starts with an empty string buffer.
693       *  @param  __m  Whether the buffer can read, or write, or both.
694       *
695       *  Initializes @c sb using the mode from @c __m, and passes @c
696       *  &sb to the base class initializer.  Does not allocate any
697       *  buffer.
698       *
699       *  That's a lie.  We initialize the base class with NULL, because the
700       *  string class does its own memory management.
701      */
702      explicit
703      basic_stringstream(ios_base::openmode __m = ios_base::out | ios_base::in)
704      : __iostream_type(), _M_stringbuf(__m)
705      { this->init(&_M_stringbuf); }
706
707      /**
708       *  @brief  Starts with an existing string buffer.
709       *  @param  __str  A string to copy as a starting buffer.
710       *  @param  __m  Whether the buffer can read, or write, or both.
711       *
712       *  Initializes @c sb using @a __str and @c __m, and passes @c &sb
713       *  to the base class initializer.
714       *
715       *  That's a lie.  We initialize the base class with NULL, because the
716       *  string class does its own memory management.
717      */
718      explicit
719      basic_stringstream(const __string_type& __str,
720			 ios_base::openmode __m = ios_base::out | ios_base::in)
721      : __iostream_type(), _M_stringbuf(__str, __m)
722      { this->init(&_M_stringbuf); }
723
724      /**
725       *  @brief  The destructor does nothing.
726       *
727       *  The buffer is deallocated by the stringbuf object, not the
728       *  formatting stream.
729      */
730      ~basic_stringstream()
731      { }
732
733#if __cplusplus >= 201103L
734      basic_stringstream(const basic_stringstream&) = delete;
735
736      basic_stringstream(basic_stringstream&& __rhs)
737      : __iostream_type(std::move(__rhs)),
738      _M_stringbuf(std::move(__rhs._M_stringbuf))
739      { __iostream_type::set_rdbuf(&_M_stringbuf); }
740
741      // 27.8.3.2 Assign and swap:
742
743      basic_stringstream&
744      operator=(const basic_stringstream&) = delete;
745
746      basic_stringstream&
747      operator=(basic_stringstream&& __rhs)
748      {
749	__iostream_type::operator=(std::move(__rhs));
750	_M_stringbuf = std::move(__rhs._M_stringbuf);
751	return *this;
752      }
753
754      void
755      swap(basic_stringstream& __rhs)
756      {
757	__iostream_type::swap(__rhs);
758	_M_stringbuf.swap(__rhs._M_stringbuf);
759      }
760#endif
761
762      // Members:
763      /**
764       *  @brief  Accessing the underlying buffer.
765       *  @return  The current basic_stringbuf buffer.
766       *
767       *  This hides both signatures of std::basic_ios::rdbuf().
768      */
769      __stringbuf_type*
770      rdbuf() const
771      { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
772
773      /**
774       *  @brief  Copying out the string buffer.
775       *  @return  @c rdbuf()->str()
776      */
777      __string_type
778      str() const
779      { return _M_stringbuf.str(); }
780
781      /**
782       *  @brief  Setting a new buffer.
783       *  @param  __s  The string to use as a new sequence.
784       *
785       *  Calls @c rdbuf()->str(s).
786      */
787      void
788      str(const __string_type& __s)
789      { _M_stringbuf.str(__s); }
790    };
791
792#if __cplusplus >= 201103L
793  /// Swap specialization for stringbufs.
794  template <class _CharT, class _Traits, class _Allocator>
795    inline void
796    swap(basic_stringbuf<_CharT, _Traits, _Allocator>& __x,
797	 basic_stringbuf<_CharT, _Traits, _Allocator>& __y)
798    { __x.swap(__y); }
799
800  /// Swap specialization for istringstreams.
801  template <class _CharT, class _Traits, class _Allocator>
802    inline void
803    swap(basic_istringstream<_CharT, _Traits, _Allocator>& __x,
804	 basic_istringstream<_CharT, _Traits, _Allocator>& __y)
805    { __x.swap(__y); }
806
807  /// Swap specialization for ostringstreams.
808  template <class _CharT, class _Traits, class _Allocator>
809    inline void
810    swap(basic_ostringstream<_CharT, _Traits, _Allocator>& __x,
811	 basic_ostringstream<_CharT, _Traits, _Allocator>& __y)
812    { __x.swap(__y); }
813
814  /// Swap specialization for stringstreams.
815  template <class _CharT, class _Traits, class _Allocator>
816    inline void
817    swap(basic_stringstream<_CharT, _Traits, _Allocator>& __x,
818	 basic_stringstream<_CharT, _Traits, _Allocator>& __y)
819    { __x.swap(__y); }
820#endif
821
822_GLIBCXX_END_NAMESPACE_CXX11
823_GLIBCXX_END_NAMESPACE_VERSION
824} // namespace
825
826#include <bits/sstream.tcc>
827
828#endif /* _GLIBCXX_SSTREAM */
829