libstdc++
ios_base.h
Go to the documentation of this file.
1 // Iostreams base classes -*- C++ -*-
2 
3 // Copyright (C) 1997-2019 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file bits/ios_base.h
26  * This is an internal header file, included by other library headers.
27  * Do not attempt to use it directly. @headername{ios}
28  */
29 
30 //
31 // ISO C++ 14882: 27.4 Iostreams base classes
32 //
33 
34 #ifndef _IOS_BASE_H
35 #define _IOS_BASE_H 1
36 
37 #pragma GCC system_header
38 
39 #include <ext/atomicity.h>
40 #include <bits/localefwd.h>
41 #include <bits/locale_classes.h>
42 
43 #if __cplusplus < 201103L
44 # include <stdexcept>
45 #else
46 # include <system_error>
47 #endif
48 
49 namespace std _GLIBCXX_VISIBILITY(default)
50 {
51 _GLIBCXX_BEGIN_NAMESPACE_VERSION
52 
53  // The following definitions of bitmask types are enums, not ints,
54  // as permitted (but not required) in the standard, in order to provide
55  // better type safety in iostream calls. A side effect is that in C++98
56  // expressions involving them are not compile-time constants.
57  enum _Ios_Fmtflags
58  {
59  _S_boolalpha = 1L << 0,
60  _S_dec = 1L << 1,
61  _S_fixed = 1L << 2,
62  _S_hex = 1L << 3,
63  _S_internal = 1L << 4,
64  _S_left = 1L << 5,
65  _S_oct = 1L << 6,
66  _S_right = 1L << 7,
67  _S_scientific = 1L << 8,
68  _S_showbase = 1L << 9,
69  _S_showpoint = 1L << 10,
70  _S_showpos = 1L << 11,
71  _S_skipws = 1L << 12,
72  _S_unitbuf = 1L << 13,
73  _S_uppercase = 1L << 14,
74  _S_adjustfield = _S_left | _S_right | _S_internal,
75  _S_basefield = _S_dec | _S_oct | _S_hex,
76  _S_floatfield = _S_scientific | _S_fixed,
77  _S_ios_fmtflags_end = 1L << 16,
78  _S_ios_fmtflags_max = __INT_MAX__,
79  _S_ios_fmtflags_min = ~__INT_MAX__
80  };
81 
82  inline _GLIBCXX_CONSTEXPR _Ios_Fmtflags
83  operator&(_Ios_Fmtflags __a, _Ios_Fmtflags __b)
84  { return _Ios_Fmtflags(static_cast<int>(__a) & static_cast<int>(__b)); }
85 
86  inline _GLIBCXX_CONSTEXPR _Ios_Fmtflags
87  operator|(_Ios_Fmtflags __a, _Ios_Fmtflags __b)
88  { return _Ios_Fmtflags(static_cast<int>(__a) | static_cast<int>(__b)); }
89 
90  inline _GLIBCXX_CONSTEXPR _Ios_Fmtflags
91  operator^(_Ios_Fmtflags __a, _Ios_Fmtflags __b)
92  { return _Ios_Fmtflags(static_cast<int>(__a) ^ static_cast<int>(__b)); }
93 
94  inline _GLIBCXX_CONSTEXPR _Ios_Fmtflags
95  operator~(_Ios_Fmtflags __a)
96  { return _Ios_Fmtflags(~static_cast<int>(__a)); }
97 
98  inline const _Ios_Fmtflags&
99  operator|=(_Ios_Fmtflags& __a, _Ios_Fmtflags __b)
100  { return __a = __a | __b; }
101 
102  inline const _Ios_Fmtflags&
103  operator&=(_Ios_Fmtflags& __a, _Ios_Fmtflags __b)
104  { return __a = __a & __b; }
105 
106  inline const _Ios_Fmtflags&
107  operator^=(_Ios_Fmtflags& __a, _Ios_Fmtflags __b)
108  { return __a = __a ^ __b; }
109 
110 
111  enum _Ios_Openmode
112  {
113  _S_app = 1L << 0,
114  _S_ate = 1L << 1,
115  _S_bin = 1L << 2,
116  _S_in = 1L << 3,
117  _S_out = 1L << 4,
118  _S_trunc = 1L << 5,
119  _S_ios_openmode_end = 1L << 16,
120  _S_ios_openmode_max = __INT_MAX__,
121  _S_ios_openmode_min = ~__INT_MAX__
122  };
123 
124  inline _GLIBCXX_CONSTEXPR _Ios_Openmode
125  operator&(_Ios_Openmode __a, _Ios_Openmode __b)
126  { return _Ios_Openmode(static_cast<int>(__a) & static_cast<int>(__b)); }
127 
128  inline _GLIBCXX_CONSTEXPR _Ios_Openmode
129  operator|(_Ios_Openmode __a, _Ios_Openmode __b)
130  { return _Ios_Openmode(static_cast<int>(__a) | static_cast<int>(__b)); }
131 
132  inline _GLIBCXX_CONSTEXPR _Ios_Openmode
133  operator^(_Ios_Openmode __a, _Ios_Openmode __b)
134  { return _Ios_Openmode(static_cast<int>(__a) ^ static_cast<int>(__b)); }
135 
136  inline _GLIBCXX_CONSTEXPR _Ios_Openmode
137  operator~(_Ios_Openmode __a)
138  { return _Ios_Openmode(~static_cast<int>(__a)); }
139 
140  inline const _Ios_Openmode&
141  operator|=(_Ios_Openmode& __a, _Ios_Openmode __b)
142  { return __a = __a | __b; }
143 
144  inline const _Ios_Openmode&
145  operator&=(_Ios_Openmode& __a, _Ios_Openmode __b)
146  { return __a = __a & __b; }
147 
148  inline const _Ios_Openmode&
149  operator^=(_Ios_Openmode& __a, _Ios_Openmode __b)
150  { return __a = __a ^ __b; }
151 
152 
153  enum _Ios_Iostate
154  {
155  _S_goodbit = 0,
156  _S_badbit = 1L << 0,
157  _S_eofbit = 1L << 1,
158  _S_failbit = 1L << 2,
159  _S_ios_iostate_end = 1L << 16,
160  _S_ios_iostate_max = __INT_MAX__,
161  _S_ios_iostate_min = ~__INT_MAX__
162  };
163 
164  inline _GLIBCXX_CONSTEXPR _Ios_Iostate
165  operator&(_Ios_Iostate __a, _Ios_Iostate __b)
166  { return _Ios_Iostate(static_cast<int>(__a) & static_cast<int>(__b)); }
167 
168  inline _GLIBCXX_CONSTEXPR _Ios_Iostate
169  operator|(_Ios_Iostate __a, _Ios_Iostate __b)
170  { return _Ios_Iostate(static_cast<int>(__a) | static_cast<int>(__b)); }
171 
172  inline _GLIBCXX_CONSTEXPR _Ios_Iostate
173  operator^(_Ios_Iostate __a, _Ios_Iostate __b)
174  { return _Ios_Iostate(static_cast<int>(__a) ^ static_cast<int>(__b)); }
175 
176  inline _GLIBCXX_CONSTEXPR _Ios_Iostate
177  operator~(_Ios_Iostate __a)
178  { return _Ios_Iostate(~static_cast<int>(__a)); }
179 
180  inline const _Ios_Iostate&
181  operator|=(_Ios_Iostate& __a, _Ios_Iostate __b)
182  { return __a = __a | __b; }
183 
184  inline const _Ios_Iostate&
185  operator&=(_Ios_Iostate& __a, _Ios_Iostate __b)
186  { return __a = __a & __b; }
187 
188  inline const _Ios_Iostate&
189  operator^=(_Ios_Iostate& __a, _Ios_Iostate __b)
190  { return __a = __a ^ __b; }
191 
192 
193  enum _Ios_Seekdir
194  {
195  _S_beg = 0,
196  _S_cur = _GLIBCXX_STDIO_SEEK_CUR,
197  _S_end = _GLIBCXX_STDIO_SEEK_END,
198  _S_ios_seekdir_end = 1L << 16
199  };
200 
201 #if __cplusplus >= 201103L
202  /// I/O error code
203  enum class io_errc { stream = 1 };
204 
205  template <> struct is_error_code_enum<io_errc> : public true_type { };
206 
207  const error_category& iostream_category() noexcept;
208 
209  inline error_code
210  make_error_code(io_errc __e) noexcept
211  { return error_code(static_cast<int>(__e), iostream_category()); }
212 
213  inline error_condition
214  make_error_condition(io_errc __e) noexcept
215  { return error_condition(static_cast<int>(__e), iostream_category()); }
216 #endif
217 
218  // 27.4.2 Class ios_base
219  /**
220  * @brief The base of the I/O class hierarchy.
221  * @ingroup io
222  *
223  * This class defines everything that can be defined about I/O that does
224  * not depend on the type of characters being input or output. Most
225  * people will only see @c ios_base when they need to specify the full
226  * name of the various I/O flags (e.g., the openmodes).
227  */
228  class ios_base
229  {
230 #if _GLIBCXX_USE_CXX11_ABI
231 #if __cplusplus < 201103L
232  // Type that is layout-compatible with std::system_error
234  {
235  // Type that is layout-compatible with std::error_code
236  struct error_code
237  {
238  error_code() { }
239  private:
240  int _M_value;
241  const void* _M_cat;
242  } _M_code;
243  };
244 #endif
245 #endif
246  public:
247 
248  /**
249  * @brief These are thrown to indicate problems with io.
250  * @ingroup exceptions
251  *
252  * 27.4.2.1.1 Class ios_base::failure
253  */
254 #if _GLIBCXX_USE_CXX11_ABI
255  class _GLIBCXX_ABI_TAG_CXX11 failure : public system_error
256  {
257  public:
258  explicit
259  failure(const string& __str);
260 
261 #if __cplusplus >= 201103L
262  explicit
263  failure(const string&, const error_code&);
264 
265  explicit
266  failure(const char*, const error_code& = io_errc::stream);
267 #endif
268 
269  virtual
270  ~failure() throw();
271 
272  virtual const char*
273  what() const throw();
274  };
275 #else
276  class failure : public exception
277  {
278  public:
279  // _GLIBCXX_RESOLVE_LIB_DEFECTS
280  // 48. Use of non-existent exception constructor
281  explicit
282  failure(const string& __str) throw();
283 
284  // This declaration is not useless:
285  // http://gcc.gnu.org/onlinedocs/gcc-4.3.2/gcc/Vague-Linkage.html
286  virtual
287  ~failure() throw();
288 
289  virtual const char*
290  what() const throw();
291 
292  private:
293  string _M_msg;
294  };
295 #endif
296 
297  // 27.4.2.1.2 Type ios_base::fmtflags
298  /**
299  * @brief This is a bitmask type.
300  *
301  * @c @a _Ios_Fmtflags is implementation-defined, but it is valid to
302  * perform bitwise operations on these values and expect the Right
303  * Thing to happen. Defined objects of type fmtflags are:
304  * - boolalpha
305  * - dec
306  * - fixed
307  * - hex
308  * - internal
309  * - left
310  * - oct
311  * - right
312  * - scientific
313  * - showbase
314  * - showpoint
315  * - showpos
316  * - skipws
317  * - unitbuf
318  * - uppercase
319  * - adjustfield
320  * - basefield
321  * - floatfield
322  */
323  typedef _Ios_Fmtflags fmtflags;
324 
325  /// Insert/extract @c bool in alphabetic rather than numeric format.
326  static const fmtflags boolalpha = _S_boolalpha;
327 
328  /// Converts integer input or generates integer output in decimal base.
329  static const fmtflags dec = _S_dec;
330 
331  /// Generate floating-point output in fixed-point notation.
332  static const fmtflags fixed = _S_fixed;
333 
334  /// Converts integer input or generates integer output in hexadecimal base.
335  static const fmtflags hex = _S_hex;
336 
337  /// Adds fill characters at a designated internal point in certain
338  /// generated output, or identical to @c right if no such point is
339  /// designated.
340  static const fmtflags internal = _S_internal;
341 
342  /// Adds fill characters on the right (final positions) of certain
343  /// generated output. (I.e., the thing you print is flush left.)
344  static const fmtflags left = _S_left;
345 
346  /// Converts integer input or generates integer output in octal base.
347  static const fmtflags oct = _S_oct;
348 
349  /// Adds fill characters on the left (initial positions) of certain
350  /// generated output. (I.e., the thing you print is flush right.)
351  static const fmtflags right = _S_right;
352 
353  /// Generates floating-point output in scientific notation.
354  static const fmtflags scientific = _S_scientific;
355 
356  /// Generates a prefix indicating the numeric base of generated integer
357  /// output.
358  static const fmtflags showbase = _S_showbase;
359 
360  /// Generates a decimal-point character unconditionally in generated
361  /// floating-point output.
362  static const fmtflags showpoint = _S_showpoint;
363 
364  /// Generates a + sign in non-negative generated numeric output.
365  static const fmtflags showpos = _S_showpos;
366 
367  /// Skips leading white space before certain input operations.
368  static const fmtflags skipws = _S_skipws;
369 
370  /// Flushes output after each output operation.
371  static const fmtflags unitbuf = _S_unitbuf;
372 
373  /// Replaces certain lowercase letters with their uppercase equivalents
374  /// in generated output.
375  static const fmtflags uppercase = _S_uppercase;
376 
377  /// A mask of left|right|internal. Useful for the 2-arg form of @c setf.
378  static const fmtflags adjustfield = _S_adjustfield;
379 
380  /// A mask of dec|oct|hex. Useful for the 2-arg form of @c setf.
381  static const fmtflags basefield = _S_basefield;
382 
383  /// A mask of scientific|fixed. Useful for the 2-arg form of @c setf.
384  static const fmtflags floatfield = _S_floatfield;
385 
386  // 27.4.2.1.3 Type ios_base::iostate
387  /**
388  * @brief This is a bitmask type.
389  *
390  * @c @a _Ios_Iostate is implementation-defined, but it is valid to
391  * perform bitwise operations on these values and expect the Right
392  * Thing to happen. Defined objects of type iostate are:
393  * - badbit
394  * - eofbit
395  * - failbit
396  * - goodbit
397  */
398  typedef _Ios_Iostate iostate;
399 
400  /// Indicates a loss of integrity in an input or output sequence (such
401  /// as an irrecoverable read error from a file).
402  static const iostate badbit = _S_badbit;
403 
404  /// Indicates that an input operation reached the end of an input sequence.
405  static const iostate eofbit = _S_eofbit;
406 
407  /// Indicates that an input operation failed to read the expected
408  /// characters, or that an output operation failed to generate the
409  /// desired characters.
410  static const iostate failbit = _S_failbit;
411 
412  /// Indicates all is well.
413  static const iostate goodbit = _S_goodbit;
414 
415  // 27.4.2.1.4 Type ios_base::openmode
416  /**
417  * @brief This is a bitmask type.
418  *
419  * @c @a _Ios_Openmode is implementation-defined, but it is valid to
420  * perform bitwise operations on these values and expect the Right
421  * Thing to happen. Defined objects of type openmode are:
422  * - app
423  * - ate
424  * - binary
425  * - in
426  * - out
427  * - trunc
428  */
429  typedef _Ios_Openmode openmode;
430 
431  /// Seek to end before each write.
432  static const openmode app = _S_app;
433 
434  /// Open and seek to end immediately after opening.
435  static const openmode ate = _S_ate;
436 
437  /// Perform input and output in binary mode (as opposed to text mode).
438  /// This is probably not what you think it is; see
439  /// https://gcc.gnu.org/onlinedocs/libstdc++/manual/fstreams.html#std.io.filestreams.binary
440  static const openmode binary = _S_bin;
441 
442  /// Open for input. Default for @c ifstream and fstream.
443  static const openmode in = _S_in;
444 
445  /// Open for output. Default for @c ofstream and fstream.
446  static const openmode out = _S_out;
447 
448  /// Truncate an existing stream when opening. Default for @c ofstream.
449  static const openmode trunc = _S_trunc;
450 
451  // 27.4.2.1.5 Type ios_base::seekdir
452  /**
453  * @brief This is an enumerated type.
454  *
455  * @c @a _Ios_Seekdir is implementation-defined. Defined values
456  * of type seekdir are:
457  * - beg
458  * - cur, equivalent to @c SEEK_CUR in the C standard library.
459  * - end, equivalent to @c SEEK_END in the C standard library.
460  */
461  typedef _Ios_Seekdir seekdir;
462 
463  /// Request a seek relative to the beginning of the stream.
464  static const seekdir beg = _S_beg;
465 
466  /// Request a seek relative to the current position within the sequence.
467  static const seekdir cur = _S_cur;
468 
469  /// Request a seek relative to the current end of the sequence.
470  static const seekdir end = _S_end;
471 
472 #if __cplusplus <= 201402L
473  // Annex D.6 (removed in C++17)
474  typedef int io_state
475  _GLIBCXX_DEPRECATED_SUGGEST("std::iostate");
476  typedef int open_mode
477  _GLIBCXX_DEPRECATED_SUGGEST("std::openmode");
478  typedef int seek_dir
479  _GLIBCXX_DEPRECATED_SUGGEST("std::seekdir");
480 
481  typedef std::streampos streampos
482  _GLIBCXX_DEPRECATED_SUGGEST("std::streampos");
483  typedef std::streamoff streamoff
484  _GLIBCXX_DEPRECATED_SUGGEST("std::streamoff");
485 #endif
486 
487  // Callbacks;
488  /**
489  * @brief The set of events that may be passed to an event callback.
490  *
491  * erase_event is used during ~ios() and copyfmt(). imbue_event is used
492  * during imbue(). copyfmt_event is used during copyfmt().
493  */
494  enum event
495  {
496  erase_event,
497  imbue_event,
498  copyfmt_event
499  };
500 
501  /**
502  * @brief The type of an event callback function.
503  * @param __e One of the members of the event enum.
504  * @param __b Reference to the ios_base object.
505  * @param __i The integer provided when the callback was registered.
506  *
507  * Event callbacks are user defined functions that get called during
508  * several ios_base and basic_ios functions, specifically imbue(),
509  * copyfmt(), and ~ios().
510  */
511  typedef void (*event_callback) (event __e, ios_base& __b, int __i);
512 
513  /**
514  * @brief Add the callback __fn with parameter __index.
515  * @param __fn The function to add.
516  * @param __index The integer to pass to the function when invoked.
517  *
518  * Registers a function as an event callback with an integer parameter to
519  * be passed to the function when invoked. Multiple copies of the
520  * function are allowed. If there are multiple callbacks, they are
521  * invoked in the order they were registered.
522  */
523  void
524  register_callback(event_callback __fn, int __index);
525 
526  protected:
527  streamsize _M_precision;
528  streamsize _M_width;
529  fmtflags _M_flags;
530  iostate _M_exception;
531  iostate _M_streambuf_state;
532 
533  // 27.4.2.6 Members for callbacks
534  // 27.4.2.6 ios_base callbacks
535  struct _Callback_list
536  {
537  // Data Members
538  _Callback_list* _M_next;
540  int _M_index;
541  _Atomic_word _M_refcount; // 0 means one reference.
542 
543  _Callback_list(ios_base::event_callback __fn, int __index,
544  _Callback_list* __cb)
545  : _M_next(__cb), _M_fn(__fn), _M_index(__index), _M_refcount(0) { }
546 
547  void
548  _M_add_reference() { __gnu_cxx::__atomic_add_dispatch(&_M_refcount, 1); }
549 
550  // 0 => OK to delete.
551  int
552  _M_remove_reference()
553  {
554  // Be race-detector-friendly. For more info see bits/c++config.
555  _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount);
556  int __res = __gnu_cxx::__exchange_and_add_dispatch(&_M_refcount, -1);
557  if (__res == 0)
558  {
559  _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount);
560  }
561  return __res;
562  }
563  };
564 
565  _Callback_list* _M_callbacks;
566 
567  void
568  _M_call_callbacks(event __ev) throw();
569 
570  void
571  _M_dispose_callbacks(void) throw();
572 
573  // 27.4.2.5 Members for iword/pword storage
574  struct _Words
575  {
576  void* _M_pword;
577  long _M_iword;
578  _Words() : _M_pword(0), _M_iword(0) { }
579  };
580 
581  // Only for failed iword/pword calls.
582  _Words _M_word_zero;
583 
584  // Guaranteed storage.
585  // The first 5 iword and pword slots are reserved for internal use.
586  enum { _S_local_word_size = 8 };
587  _Words _M_local_word[_S_local_word_size];
588 
589  // Allocated storage.
590  int _M_word_size;
591  _Words* _M_word;
592 
593  _Words&
594  _M_grow_words(int __index, bool __iword);
595 
596  // Members for locale and locale caching.
597  locale _M_ios_locale;
598 
599  void
600  _M_init() throw();
601 
602  public:
603 
604  // 27.4.2.1.6 Class ios_base::Init
605  // Used to initialize standard streams. In theory, g++ could use
606  // -finit-priority to order this stuff correctly without going
607  // through these machinations.
608  class Init
609  {
610  friend class ios_base;
611  public:
612  Init();
613  ~Init();
614 
615 #if __cplusplus >= 201103L
616  Init(const Init&) = default;
617  Init& operator=(const Init&) = default;
618 #endif
619 
620  private:
621  static _Atomic_word _S_refcount;
622  static bool _S_synced_with_stdio;
623  };
624 
625  // [27.4.2.2] fmtflags state functions
626  /**
627  * @brief Access to format flags.
628  * @return The format control flags for both input and output.
629  */
630  fmtflags
631  flags() const
632  { return _M_flags; }
633 
634  /**
635  * @brief Setting new format flags all at once.
636  * @param __fmtfl The new flags to set.
637  * @return The previous format control flags.
638  *
639  * This function overwrites all the format flags with @a __fmtfl.
640  */
641  fmtflags
642  flags(fmtflags __fmtfl)
643  {
644  fmtflags __old = _M_flags;
645  _M_flags = __fmtfl;
646  return __old;
647  }
648 
649  /**
650  * @brief Setting new format flags.
651  * @param __fmtfl Additional flags to set.
652  * @return The previous format control flags.
653  *
654  * This function sets additional flags in format control. Flags that
655  * were previously set remain set.
656  */
657  fmtflags
658  setf(fmtflags __fmtfl)
659  {
660  fmtflags __old = _M_flags;
661  _M_flags |= __fmtfl;
662  return __old;
663  }
664 
665  /**
666  * @brief Setting new format flags.
667  * @param __fmtfl Additional flags to set.
668  * @param __mask The flags mask for @a fmtfl.
669  * @return The previous format control flags.
670  *
671  * This function clears @a mask in the format flags, then sets
672  * @a fmtfl @c & @a mask. An example mask is @c ios_base::adjustfield.
673  */
674  fmtflags
675  setf(fmtflags __fmtfl, fmtflags __mask)
676  {
677  fmtflags __old = _M_flags;
678  _M_flags &= ~__mask;
679  _M_flags |= (__fmtfl & __mask);
680  return __old;
681  }
682 
683  /**
684  * @brief Clearing format flags.
685  * @param __mask The flags to unset.
686  *
687  * This function clears @a __mask in the format flags.
688  */
689  void
690  unsetf(fmtflags __mask)
691  { _M_flags &= ~__mask; }
692 
693  /**
694  * @brief Flags access.
695  * @return The precision to generate on certain output operations.
696  *
697  * Be careful if you try to give a definition of @a precision here; see
698  * DR 189.
699  */
700  streamsize
701  precision() const
702  { return _M_precision; }
703 
704  /**
705  * @brief Changing flags.
706  * @param __prec The new precision value.
707  * @return The previous value of precision().
708  */
709  streamsize
711  {
712  streamsize __old = _M_precision;
713  _M_precision = __prec;
714  return __old;
715  }
716 
717  /**
718  * @brief Flags access.
719  * @return The minimum field width to generate on output operations.
720  *
721  * <em>Minimum field width</em> refers to the number of characters.
722  */
723  streamsize
724  width() const
725  { return _M_width; }
726 
727  /**
728  * @brief Changing flags.
729  * @param __wide The new width value.
730  * @return The previous value of width().
731  */
732  streamsize
734  {
735  streamsize __old = _M_width;
736  _M_width = __wide;
737  return __old;
738  }
739 
740  // [27.4.2.4] ios_base static members
741  /**
742  * @brief Interaction with the standard C I/O objects.
743  * @param __sync Whether to synchronize or not.
744  * @return True if the standard streams were previously synchronized.
745  *
746  * The synchronization referred to is @e only that between the standard
747  * C facilities (e.g., stdout) and the standard C++ objects (e.g.,
748  * cout). User-declared streams are unaffected. See
749  * https://gcc.gnu.org/onlinedocs/libstdc++/manual/fstreams.html#std.io.filestreams.binary
750  */
751  static bool
752  sync_with_stdio(bool __sync = true);
753 
754  // [27.4.2.3] ios_base locale functions
755  /**
756  * @brief Setting a new locale.
757  * @param __loc The new locale.
758  * @return The previous locale.
759  *
760  * Sets the new locale for this stream, and then invokes each callback
761  * with imbue_event.
762  */
763  locale
764  imbue(const locale& __loc) throw();
765 
766  /**
767  * @brief Locale access
768  * @return A copy of the current locale.
769  *
770  * If @c imbue(loc) has previously been called, then this function
771  * returns @c loc. Otherwise, it returns a copy of @c std::locale(),
772  * the global C++ locale.
773  */
774  locale
775  getloc() const
776  { return _M_ios_locale; }
777 
778  /**
779  * @brief Locale access
780  * @return A reference to the current locale.
781  *
782  * Like getloc above, but returns a reference instead of
783  * generating a copy.
784  */
785  const locale&
786  _M_getloc() const
787  { return _M_ios_locale; }
788 
789  // [27.4.2.5] ios_base storage functions
790  /**
791  * @brief Access to unique indices.
792  * @return An integer different from all previous calls.
793  *
794  * This function returns a unique integer every time it is called. It
795  * can be used for any purpose, but is primarily intended to be a unique
796  * index for the iword and pword functions. The expectation is that an
797  * application calls xalloc in order to obtain an index in the iword and
798  * pword arrays that can be used without fear of conflict.
799  *
800  * The implementation maintains a static variable that is incremented and
801  * returned on each invocation. xalloc is guaranteed to return an index
802  * that is safe to use in the iword and pword arrays.
803  */
804  static int
805  xalloc() throw();
806 
807  /**
808  * @brief Access to integer array.
809  * @param __ix Index into the array.
810  * @return A reference to an integer associated with the index.
811  *
812  * The iword function provides access to an array of integers that can be
813  * used for any purpose. The array grows as required to hold the
814  * supplied index. All integers in the array are initialized to 0.
815  *
816  * The implementation reserves several indices. You should use xalloc to
817  * obtain an index that is safe to use. Also note that since the array
818  * can grow dynamically, it is not safe to hold onto the reference.
819  */
820  long&
821  iword(int __ix)
822  {
823  _Words& __word = ((unsigned)__ix < (unsigned)_M_word_size)
824  ? _M_word[__ix] : _M_grow_words(__ix, true);
825  return __word._M_iword;
826  }
827 
828  /**
829  * @brief Access to void pointer array.
830  * @param __ix Index into the array.
831  * @return A reference to a void* associated with the index.
832  *
833  * The pword function provides access to an array of pointers that can be
834  * used for any purpose. The array grows as required to hold the
835  * supplied index. All pointers in the array are initialized to 0.
836  *
837  * The implementation reserves several indices. You should use xalloc to
838  * obtain an index that is safe to use. Also note that since the array
839  * can grow dynamically, it is not safe to hold onto the reference.
840  */
841  void*&
842  pword(int __ix)
843  {
844  _Words& __word = ((unsigned)__ix < (unsigned)_M_word_size)
845  ? _M_word[__ix] : _M_grow_words(__ix, false);
846  return __word._M_pword;
847  }
848 
849  // Destructor
850  /**
851  * Invokes each callback with erase_event. Destroys local storage.
852  *
853  * Note that the ios_base object for the standard streams never gets
854  * destroyed. As a result, any callbacks registered with the standard
855  * streams will not get invoked with erase_event (unless copyfmt is
856  * used).
857  */
858  virtual ~ios_base();
859 
860  protected:
861  ios_base() throw ();
862 
863 #if __cplusplus < 201103L
864  // _GLIBCXX_RESOLVE_LIB_DEFECTS
865  // 50. Copy constructor and assignment operator of ios_base
866  private:
867  ios_base(const ios_base&);
868 
869  ios_base&
870  operator=(const ios_base&);
871 #else
872  public:
873  ios_base(const ios_base&) = delete;
874 
875  ios_base&
876  operator=(const ios_base&) = delete;
877 
878  protected:
879  void
880  _M_move(ios_base&) noexcept;
881 
882  void
883  _M_swap(ios_base& __rhs) noexcept;
884 #endif
885  };
886 
887  // [27.4.5.1] fmtflags manipulators
888  /// Calls base.setf(ios_base::boolalpha).
889  inline ios_base&
891  {
893  return __base;
894  }
895 
896  /// Calls base.unsetf(ios_base::boolalpha).
897  inline ios_base&
899  {
900  __base.unsetf(ios_base::boolalpha);
901  return __base;
902  }
903 
904  /// Calls base.setf(ios_base::showbase).
905  inline ios_base&
907  {
909  return __base;
910  }
911 
912  /// Calls base.unsetf(ios_base::showbase).
913  inline ios_base&
915  {
916  __base.unsetf(ios_base::showbase);
917  return __base;
918  }
919 
920  /// Calls base.setf(ios_base::showpoint).
921  inline ios_base&
923  {
925  return __base;
926  }
927 
928  /// Calls base.unsetf(ios_base::showpoint).
929  inline ios_base&
931  {
932  __base.unsetf(ios_base::showpoint);
933  return __base;
934  }
935 
936  /// Calls base.setf(ios_base::showpos).
937  inline ios_base&
939  {
941  return __base;
942  }
943 
944  /// Calls base.unsetf(ios_base::showpos).
945  inline ios_base&
947  {
948  __base.unsetf(ios_base::showpos);
949  return __base;
950  }
951 
952  /// Calls base.setf(ios_base::skipws).
953  inline ios_base&
955  {
956  __base.setf(ios_base::skipws);
957  return __base;
958  }
959 
960  /// Calls base.unsetf(ios_base::skipws).
961  inline ios_base&
963  {
964  __base.unsetf(ios_base::skipws);
965  return __base;
966  }
967 
968  /// Calls base.setf(ios_base::uppercase).
969  inline ios_base&
971  {
973  return __base;
974  }
975 
976  /// Calls base.unsetf(ios_base::uppercase).
977  inline ios_base&
979  {
980  __base.unsetf(ios_base::uppercase);
981  return __base;
982  }
983 
984  /// Calls base.setf(ios_base::unitbuf).
985  inline ios_base&
987  {
989  return __base;
990  }
991 
992  /// Calls base.unsetf(ios_base::unitbuf).
993  inline ios_base&
995  {
996  __base.unsetf(ios_base::unitbuf);
997  return __base;
998  }
999 
1000  // [27.4.5.2] adjustfield manipulators
1001  /// Calls base.setf(ios_base::internal, ios_base::adjustfield).
1002  inline ios_base&
1003  internal(ios_base& __base)
1004  {
1006  return __base;
1007  }
1008 
1009  /// Calls base.setf(ios_base::left, ios_base::adjustfield).
1010  inline ios_base&
1012  {
1014  return __base;
1015  }
1016 
1017  /// Calls base.setf(ios_base::right, ios_base::adjustfield).
1018  inline ios_base&
1020  {
1022  return __base;
1023  }
1024 
1025  // [27.4.5.3] basefield manipulators
1026  /// Calls base.setf(ios_base::dec, ios_base::basefield).
1027  inline ios_base&
1029  {
1031  return __base;
1032  }
1033 
1034  /// Calls base.setf(ios_base::hex, ios_base::basefield).
1035  inline ios_base&
1037  {
1039  return __base;
1040  }
1041 
1042  /// Calls base.setf(ios_base::oct, ios_base::basefield).
1043  inline ios_base&
1045  {
1047  return __base;
1048  }
1049 
1050  // [27.4.5.4] floatfield manipulators
1051  /// Calls base.setf(ios_base::fixed, ios_base::floatfield).
1052  inline ios_base&
1054  {
1056  return __base;
1057  }
1058 
1059  /// Calls base.setf(ios_base::scientific, ios_base::floatfield).
1060  inline ios_base&
1062  {
1064  return __base;
1065  }
1066 
1067 #if __cplusplus >= 201103L
1068  // New C++11 floatfield manipulators
1069 
1070  /// Calls
1071  /// base.setf(ios_base::fixed|ios_base::scientific, ios_base::floatfield)
1072  inline ios_base&
1074  {
1076  return __base;
1077  }
1078 
1079  /// Calls @c base.unsetf(ios_base::floatfield)
1080  inline ios_base&
1082  {
1083  __base.unsetf(ios_base::floatfield);
1084  return __base;
1085  }
1086 #endif
1087 
1088 _GLIBCXX_END_NAMESPACE_VERSION
1089 } // namespace
1090 
1091 #endif /* _IOS_BASE_H */
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:75
ISO C++ entities toplevel namespace is std.
ptrdiff_t streamsize
Integral type for I/O operation counts and buffer sizes.
Definition: postypes.h:98
ios_base & nouppercase(ios_base &__base)
Calls base.unsetf(ios_base::uppercase).
Definition: ios_base.h:978
bitset< _Nb > operator^(const bitset< _Nb > &__x, const bitset< _Nb > &__y) noexcept
Global bitwise operations on bitsets.
Definition: bitset:1451
ios_base & nounitbuf(ios_base &__base)
Calls base.unsetf(ios_base::unitbuf).
Definition: ios_base.h:994
ios_base & hexfloat(ios_base &__base)
Calls base.setf(ios_base::fixed|ios_basescientific, ios_base::floatfield)
Definition: ios_base.h:1073
ios_base & noskipws(ios_base &__base)
Calls base.unsetf(ios_base::skipws).
Definition: ios_base.h:962
bitset< _Nb > operator|(const bitset< _Nb > &__x, const bitset< _Nb > &__y) noexcept
Global bitwise operations on bitsets.
Definition: bitset:1442
long long streamoff
Type used by fpos, char_traits<char>, and char_traits<wchar_t>.
Definition: postypes.h:94
io_errc
I/O error code.
Definition: ios_base.h:203
ios_base & defaultfloat(ios_base &__base)
Calls base.unsetf(ios_base::floatfield)
Definition: ios_base.h:1081
bitset< _Nb > operator&(const bitset< _Nb > &__x, const bitset< _Nb > &__y) noexcept
Global bitwise operations on bitsets.
Definition: bitset:1433
ios_base & noshowpos(ios_base &__base)
Calls base.unsetf(ios_base::showpos).
Definition: ios_base.h:946
ios_base & noshowpoint(ios_base &__base)
Calls base.unsetf(ios_base::showpoint).
Definition: ios_base.h:930
ios_base & noboolalpha(ios_base &__base)
Calls base.unsetf(ios_base::boolalpha).
Definition: ios_base.h:898
ios_base & noshowbase(ios_base &__base)
Calls base.unsetf(ios_base::showbase).
Definition: ios_base.h:914
_Iterator __base(_Iterator __it)
One of two subclasses of exception.
Definition: stdexcept:220
error_code
Definition: system_error:147
Thrown to indicate error code of underlying system.
Definition: system_error:342
Base class for all library exceptions.
Definition: exception.h:61
The base of the I/O class hierarchy.
Definition: ios_base.h:229
fmtflags setf(fmtflags __fmtfl)
Setting new format flags.
Definition: ios_base.h:658
static const fmtflags skipws
Skips leading white space before certain input operations.
Definition: ios_base.h:368
_Ios_Fmtflags fmtflags
This is a bitmask type.
Definition: ios_base.h:323
_Ios_Iostate iostate
This is a bitmask type.
Definition: ios_base.h:398
static const fmtflags hex
Converts integer input or generates integer output in hexadecimal base.
Definition: ios_base.h:335
static const fmtflags right
Adds fill characters on the left (initial positions) of certain generated output. (I....
Definition: ios_base.h:351
static const seekdir cur
Request a seek relative to the current position within the sequence.
Definition: ios_base.h:467
static const fmtflags uppercase
Replaces certain lowercase letters with their uppercase equivalents in generated output.
Definition: ios_base.h:375
static const fmtflags basefield
A mask of dec|oct|hex. Useful for the 2-arg form of setf.
Definition: ios_base.h:381
static const seekdir beg
Request a seek relative to the beginning of the stream.
Definition: ios_base.h:464
streamsize precision() const
Flags access.
Definition: ios_base.h:701
long & iword(int __ix)
Access to integer array.
Definition: ios_base.h:821
locale imbue(const locale &__loc)
Setting a new locale.
const locale & _M_getloc() const
Locale access.
Definition: ios_base.h:786
static const fmtflags dec
Converts integer input or generates integer output in decimal base.
Definition: ios_base.h:329
static int xalloc()
Access to unique indices.
event
The set of events that may be passed to an event callback.
Definition: ios_base.h:495
fmtflags flags(fmtflags __fmtfl)
Setting new format flags all at once.
Definition: ios_base.h:642
void unsetf(fmtflags __mask)
Clearing format flags.
Definition: ios_base.h:690
static const fmtflags showpoint
Generates a decimal-point character unconditionally in generated floating-point output.
Definition: ios_base.h:362
static const seekdir end
Request a seek relative to the current end of the sequence.
Definition: ios_base.h:470
void register_callback(event_callback __fn, int __index)
Add the callback __fn with parameter __index.
void *& pword(int __ix)
Access to void pointer array.
Definition: ios_base.h:842
static const openmode in
Open for input. Default for ifstream and fstream.
Definition: ios_base.h:443
static const fmtflags showbase
Generates a prefix indicating the numeric base of generated integer output.
Definition: ios_base.h:358
void(* event_callback)(event __e, ios_base &__b, int __i)
The type of an event callback function.
Definition: ios_base.h:511
static const fmtflags internal
Adds fill characters at a designated internal point in certain generated output, or identical to righ...
Definition: ios_base.h:340
static const openmode out
Open for output. Default for ofstream and fstream.
Definition: ios_base.h:446
static const fmtflags boolalpha
Insert/extract bool in alphabetic rather than numeric format.
Definition: ios_base.h:326
virtual ~ios_base()
fmtflags flags() const
Access to format flags.
Definition: ios_base.h:631
static const iostate eofbit
Indicates that an input operation reached the end of an input sequence.
Definition: ios_base.h:405
static const fmtflags floatfield
A mask of scientific|fixed. Useful for the 2-arg form of setf.
Definition: ios_base.h:384
fmtflags setf(fmtflags __fmtfl, fmtflags __mask)
Setting new format flags.
Definition: ios_base.h:675
static const openmode binary
Perform input and output in binary mode (as opposed to text mode). This is probably not what you thin...
Definition: ios_base.h:440
static const iostate goodbit
Indicates all is well.
Definition: ios_base.h:413
static const fmtflags unitbuf
Flushes output after each output operation.
Definition: ios_base.h:371
static const iostate badbit
Indicates a loss of integrity in an input or output sequence (such as an irrecoverable read error fro...
Definition: ios_base.h:402
_Ios_Openmode openmode
This is a bitmask type.
Definition: ios_base.h:429
streamsize width() const
Flags access.
Definition: ios_base.h:724
static bool sync_with_stdio(bool __sync=true)
Interaction with the standard C I/O objects.
static const fmtflags fixed
Generate floating-point output in fixed-point notation.
Definition: ios_base.h:332
static const fmtflags oct
Converts integer input or generates integer output in octal base.
Definition: ios_base.h:347
static const openmode app
Seek to end before each write.
Definition: ios_base.h:432
_Ios_Seekdir seekdir
This is an enumerated type.
Definition: ios_base.h:461
streamsize width(streamsize __wide)
Changing flags.
Definition: ios_base.h:733
static const fmtflags left
Adds fill characters on the right (final positions) of certain generated output. (I....
Definition: ios_base.h:344
static const fmtflags showpos
Generates a + sign in non-negative generated numeric output.
Definition: ios_base.h:365
static const openmode ate
Open and seek to end immediately after opening.
Definition: ios_base.h:435
locale getloc() const
Locale access.
Definition: ios_base.h:775
static const openmode trunc
Truncate an existing stream when opening. Default for ofstream.
Definition: ios_base.h:449
streamsize precision(streamsize __prec)
Changing flags.
Definition: ios_base.h:710
static const iostate failbit
Indicates that an input operation failed to read the expected characters, or that an output operation...
Definition: ios_base.h:410
static const fmtflags scientific
Generates floating-point output in scientific notation.
Definition: ios_base.h:354
static const fmtflags adjustfield
A mask of left|right|internal. Useful for the 2-arg form of setf.
Definition: ios_base.h:378
These are thrown to indicate problems with io.
Definition: ios_base.h:277
virtual const char * what() const
Container class for localization functionality.
Class representing stream positions.
Definition: postypes.h:113