1 // Iostreams base classes -*- C++ -*-
2
3 // Copyright (C) 1997-2021 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
_GLIBCXX_VISIBILITY(default)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
233 struct system_error : std::runtime_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 #if __cplusplus >= 201103L
293 // Define the new members required by C++11,
294 // even though the error_code cannot be stored.
295
296 explicit
297 failure(const string& __s, const error_code&) noexcept
298 : failure(__s)
299 { }
300
301 explicit
302 failure(const char* __s, const error_code& = error_code{})
303 : failure(string(__s))
304 { }
305
306 // Stand-in for system_error::code() but returning by value.
307 error_code code() const noexcept { return error_code{}; }
308 #endif
309
310 private:
311 string _M_msg;
312 };
313 #endif
314
315 // 27.4.2.1.2 Type ios_base::fmtflags
316 /**
317 * @brief This is a bitmask type.
318 *
319 * @c @a _Ios_Fmtflags is implementation-defined, but it is valid to
320 * perform bitwise operations on these values and expect the Right
321 * Thing to happen. Defined objects of type fmtflags are:
322 * - boolalpha
323 * - dec
324 * - fixed
325 * - hex
326 * - internal
327 * - left
328 * - oct
329 * - right
330 * - scientific
331 * - showbase
332 * - showpoint
333 * - showpos
334 * - skipws
335 * - unitbuf
336 * - uppercase
337 * - adjustfield
338 * - basefield
339 * - floatfield
340 */
341 typedef _Ios_Fmtflags fmtflags;
342
343 /// Insert/extract @c bool in alphabetic rather than numeric format.
344 static const fmtflags boolalpha = _S_boolalpha;
345
346 /// Converts integer input or generates integer output in decimal base.
347 static const fmtflags dec = _S_dec;
348
349 /// Generate floating-point output in fixed-point notation.
350 static const fmtflags fixed = _S_fixed;
351
352 /// Converts integer input or generates integer output in hexadecimal base.
353 static const fmtflags hex = _S_hex;
354
355 /// Adds fill characters at a designated internal point in certain
356 /// generated output, or identical to @c right if no such point is
357 /// designated.
358 static const fmtflags internal = _S_internal;
359
360 /// Adds fill characters on the right (final positions) of certain
361 /// generated output. (I.e., the thing you print is flush left.)
362 static const fmtflags left = _S_left;
363
364 /// Converts integer input or generates integer output in octal base.
365 static const fmtflags oct = _S_oct;
366
367 /// Adds fill characters on the left (initial positions) of certain
368 /// generated output. (I.e., the thing you print is flush right.)
369 static const fmtflags right = _S_right;
370
371 /// Generates floating-point output in scientific notation.
372 static const fmtflags scientific = _S_scientific;
373
374 /// Generates a prefix indicating the numeric base of generated integer
375 /// output.
376 static const fmtflags showbase = _S_showbase;
377
378 /// Generates a decimal-point character unconditionally in generated
379 /// floating-point output.
380 static const fmtflags showpoint = _S_showpoint;
381
382 /// Generates a + sign in non-negative generated numeric output.
383 static const fmtflags showpos = _S_showpos;
384
385 /// Skips leading white space before certain input operations.
386 static const fmtflags skipws = _S_skipws;
387
388 /// Flushes output after each output operation.
389 static const fmtflags unitbuf = _S_unitbuf;
390
391 /// Replaces certain lowercase letters with their uppercase equivalents
392 /// in generated output.
393 static const fmtflags uppercase = _S_uppercase;
394
395 /// A mask of left|right|internal. Useful for the 2-arg form of @c setf.
396 static const fmtflags adjustfield = _S_adjustfield;
397
398 /// A mask of dec|oct|hex. Useful for the 2-arg form of @c setf.
399 static const fmtflags basefield = _S_basefield;
400
401 /// A mask of scientific|fixed. Useful for the 2-arg form of @c setf.
402 static const fmtflags floatfield = _S_floatfield;
403
404 // 27.4.2.1.3 Type ios_base::iostate
405 /**
406 * @brief This is a bitmask type.
407 *
408 * @c @a _Ios_Iostate is implementation-defined, but it is valid to
409 * perform bitwise operations on these values and expect the Right
410 * Thing to happen. Defined objects of type iostate are:
411 * - badbit
412 * - eofbit
413 * - failbit
414 * - goodbit
415 */
416 typedef _Ios_Iostate iostate;
417
418 /// Indicates a loss of integrity in an input or output sequence (such
419 /// as an irrecoverable read error from a file).
420 static const iostate badbit = _S_badbit;
421
422 /// Indicates that an input operation reached the end of an input sequence.
423 static const iostate eofbit = _S_eofbit;
424
425 /// Indicates that an input operation failed to read the expected
426 /// characters, or that an output operation failed to generate the
427 /// desired characters.
428 static const iostate failbit = _S_failbit;
429
430 /// Indicates all is well.
431 static const iostate goodbit = _S_goodbit;
432
433 // 27.4.2.1.4 Type ios_base::openmode
434 /**
435 * @brief This is a bitmask type.
436 *
437 * @c @a _Ios_Openmode is implementation-defined, but it is valid to
438 * perform bitwise operations on these values and expect the Right
439 * Thing to happen. Defined objects of type openmode are:
440 * - app
441 * - ate
442 * - binary
443 * - in
444 * - out
445 * - trunc
446 */
447 typedef _Ios_Openmode openmode;
448
449 /// Seek to end before each write.
450 static const openmode app = _S_app;
451
452 /// Open and seek to end immediately after opening.
453 static const openmode ate = _S_ate;
454
455 /// Perform input and output in binary mode (as opposed to text mode).
456 /// This is probably not what you think it is; see
457 /// https://gcc.gnu.org/onlinedocs/libstdc++/manual/fstreams.html#std.io.filestreams.binary
458 static const openmode binary = _S_bin;
459
460 /// Open for input. Default for @c ifstream and fstream.
461 static const openmode in = _S_in;
462
463 /// Open for output. Default for @c ofstream and fstream.
464 static const openmode out = _S_out;
465
466 /// Truncate an existing stream when opening. Default for @c ofstream.
467 static const openmode trunc = _S_trunc;
468
469 // 27.4.2.1.5 Type ios_base::seekdir
470 /**
471 * @brief This is an enumerated type.
472 *
473 * @c @a _Ios_Seekdir is implementation-defined. Defined values
474 * of type seekdir are:
475 * - beg
476 * - cur, equivalent to @c SEEK_CUR in the C standard library.
477 * - end, equivalent to @c SEEK_END in the C standard library.
478 */
479 typedef _Ios_Seekdir seekdir;
480
481 /// Request a seek relative to the beginning of the stream.
482 static const seekdir beg = _S_beg;
483
484 /// Request a seek relative to the current position within the sequence.
485 static const seekdir cur = _S_cur;
486
487 /// Request a seek relative to the current end of the sequence.
488 static const seekdir end = _S_end;
489
490 #if __cplusplus <= 201402L
491 // Annex D.6 (removed in C++17)
492 typedef int io_state
493 _GLIBCXX_DEPRECATED_SUGGEST("std::iostate");
494 typedef int open_mode
495 _GLIBCXX_DEPRECATED_SUGGEST("std::openmode");
496 typedef int seek_dir
497 _GLIBCXX_DEPRECATED_SUGGEST("std::seekdir");
498
499 typedef std::streampos streampos
500 _GLIBCXX_DEPRECATED_SUGGEST("std::streampos");
501 typedef std::streamoff streamoff
502 _GLIBCXX_DEPRECATED_SUGGEST("std::streamoff");
503 #endif
504
505 // Callbacks;
506 /**
507 * @brief The set of events that may be passed to an event callback.
508 *
509 * erase_event is used during ~ios() and copyfmt(). imbue_event is used
510 * during imbue(). copyfmt_event is used during copyfmt().
511 */
512 enum event
513 {
514 erase_event,
515 imbue_event,
516 copyfmt_event
517 };
518
519 /**
520 * @brief The type of an event callback function.
521 * @param __e One of the members of the event enum.
522 * @param __b Reference to the ios_base object.
523 * @param __i The integer provided when the callback was registered.
524 *
525 * Event callbacks are user defined functions that get called during
526 * several ios_base and basic_ios functions, specifically imbue(),
527 * copyfmt(), and ~ios().
528 */
529 typedef void (*event_callback) (event __e, ios_base& __b, int __i);
530
531 /**
532 * @brief Add the callback __fn with parameter __index.
533 * @param __fn The function to add.
534 * @param __index The integer to pass to the function when invoked.
535 *
536 * Registers a function as an event callback with an integer parameter to
537 * be passed to the function when invoked. Multiple copies of the
538 * function are allowed. If there are multiple callbacks, they are
539 * invoked in the order they were registered.
540 */
541 void
542 register_callback(event_callback __fn, int __index);
543
544 protected:
545 streamsize _M_precision;
546 streamsize _M_width;
547 fmtflags _M_flags;
548 iostate _M_exception;
549 iostate _M_streambuf_state;
550
551 // 27.4.2.6 Members for callbacks
552 // 27.4.2.6 ios_base callbacks
553 struct _Callback_list
554 {
555 // Data Members
556 _Callback_list* _M_next;
557 ios_base::event_callback _M_fn;
558 int _M_index;
559 _Atomic_word _M_refcount; // 0 means one reference.
560
561 _Callback_list(ios_base::event_callback __fn, int __index,
562 _Callback_list* __cb)
563 : _M_next(__cb), _M_fn(__fn), _M_index(__index), _M_refcount(0) { }
564
565 void
566 _M_add_reference() { __gnu_cxx::__atomic_add_dispatch(&_M_refcount, 1); }
567
568 // 0 => OK to delete.
569 int
570 _M_remove_reference()
571 {
572 // Be race-detector-friendly. For more info see bits/c++config.
573 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount);
574 int __res = __gnu_cxx::__exchange_and_add_dispatch(&_M_refcount, -1);
575 if (__res == 0)
576 {
577 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount);
578 }
579 return __res;
580 }
581 };
582
583 _Callback_list* _M_callbacks;
584
585 void
586 _M_call_callbacks(event __ev) throw();
587
588 void
589 _M_dispose_callbacks(void) throw();
590
591 // 27.4.2.5 Members for iword/pword storage
592 struct _Words
593 {
594 void* _M_pword;
595 long _M_iword;
596 _Words() : _M_pword(0), _M_iword(0) { }
597 };
598
599 // Only for failed iword/pword calls.
600 _Words _M_word_zero;
601
602 // Guaranteed storage.
603 // The first 5 iword and pword slots are reserved for internal use.
604 enum { _S_local_word_size = 8 };
605 _Words _M_local_word[_S_local_word_size];
606
607 // Allocated storage.
608 int _M_word_size;
609 _Words* _M_word;
610
611 _Words&
612 _M_grow_words(int __index, bool __iword);
613
614 // Members for locale and locale caching.
615 locale _M_ios_locale;
616
617 void
618 _M_init() throw();
619
620 public:
621
622 // 27.4.2.1.6 Class ios_base::Init
623 // Used to initialize standard streams. In theory, g++ could use
624 // -finit-priority to order this stuff correctly without going
625 // through these machinations.
626 class Init
627 {
628 friend class ios_base;
629 public:
630 Init();
631 ~Init();
632
633 #if __cplusplus >= 201103L
634 Init(const Init&) = default;
635 Init& operator=(const Init&) = default;
636 #endif
637
638 private:
639 static _Atomic_word _S_refcount;
640 static bool _S_synced_with_stdio;
641 };
642
643 // [27.4.2.2] fmtflags state functions
644 /**
645 * @brief Access to format flags.
646 * @return The format control flags for both input and output.
647 */
648 fmtflags
649 flags() const
650 { return _M_flags; }
651
652 /**
653 * @brief Setting new format flags all at once.
654 * @param __fmtfl The new flags to set.
655 * @return The previous format control flags.
656 *
657 * This function overwrites all the format flags with @a __fmtfl.
658 */
659 fmtflags
660 flags(fmtflags __fmtfl)
661 {
662 fmtflags __old = _M_flags;
663 _M_flags = __fmtfl;
664 return __old;
665 }
666
667 /**
668 * @brief Setting new format flags.
669 * @param __fmtfl Additional flags to set.
670 * @return The previous format control flags.
671 *
672 * This function sets additional flags in format control. Flags that
673 * were previously set remain set.
674 */
675 fmtflags
676 setf(fmtflags __fmtfl)
677 {
678 fmtflags __old = _M_flags;
679 _M_flags |= __fmtfl;
680 return __old;
681 }
682
683 /**
684 * @brief Setting new format flags.
685 * @param __fmtfl Additional flags to set.
686 * @param __mask The flags mask for @a fmtfl.
687 * @return The previous format control flags.
688 *
689 * This function clears @a mask in the format flags, then sets
690 * @a fmtfl @c & @a mask. An example mask is @c ios_base::adjustfield.
691 */
692 fmtflags
693 setf(fmtflags __fmtfl, fmtflags __mask)
694 {
695 fmtflags __old = _M_flags;
696 _M_flags &= ~__mask;
697 _M_flags |= (__fmtfl & __mask);
698 return __old;
699 }
700
701 /**
702 * @brief Clearing format flags.
703 * @param __mask The flags to unset.
704 *
705 * This function clears @a __mask in the format flags.
706 */
707 void
708 unsetf(fmtflags __mask)
709 { _M_flags &= ~__mask; }
710
711 /**
712 * @brief Flags access.
713 * @return The precision to generate on certain output operations.
714 *
715 * Be careful if you try to give a definition of @a precision here; see
716 * DR 189.
717 */
718 streamsize
719 precision() const
720 { return _M_precision; }
721
722 /**
723 * @brief Changing flags.
724 * @param __prec The new precision value.
725 * @return The previous value of precision().
726 */
727 streamsize
728 precision(streamsize __prec)
729 {
730 streamsize __old = _M_precision;
731 _M_precision = __prec;
732 return __old;
733 }
734
735 /**
736 * @brief Flags access.
737 * @return The minimum field width to generate on output operations.
738 *
739 * <em>Minimum field width</em> refers to the number of characters.
740 */
741 streamsize
742 width() const
743 { return _M_width; }
744
745 /**
746 * @brief Changing flags.
747 * @param __wide The new width value.
748 * @return The previous value of width().
749 */
750 streamsize
751 width(streamsize __wide)
752 {
753 streamsize __old = _M_width;
754 _M_width = __wide;
755 return __old;
756 }
757
758 // [27.4.2.4] ios_base static members
759 /**
760 * @brief Interaction with the standard C I/O objects.
761 * @param __sync Whether to synchronize or not.
762 * @return True if the standard streams were previously synchronized.
763 *
764 * The synchronization referred to is @e only that between the standard
765 * C facilities (e.g., stdout) and the standard C++ objects (e.g.,
766 * cout). User-declared streams are unaffected. See
767 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/fstreams.html#std.io.filestreams.binary
768 */
769 static bool
770 sync_with_stdio(bool __sync = true);
771
772 // [27.4.2.3] ios_base locale functions
773 /**
774 * @brief Setting a new locale.
775 * @param __loc The new locale.
776 * @return The previous locale.
777 *
778 * Sets the new locale for this stream, and then invokes each callback
779 * with imbue_event.
780 */
781 locale
782 imbue(const locale& __loc) throw();
783
784 /**
785 * @brief Locale access
786 * @return A copy of the current locale.
787 *
788 * If @c imbue(loc) has previously been called, then this function
789 * returns @c loc. Otherwise, it returns a copy of @c std::locale(),
790 * the global C++ locale.
791 */
792 locale
793 getloc() const
794 { return _M_ios_locale; }
795
796 /**
797 * @brief Locale access
798 * @return A reference to the current locale.
799 *
800 * Like getloc above, but returns a reference instead of
801 * generating a copy.
802 */
803 const locale&
804 _M_getloc() const
805 { return _M_ios_locale; }
806
807 // [27.4.2.5] ios_base storage functions
808 /**
809 * @brief Access to unique indices.
810 * @return An integer different from all previous calls.
811 *
812 * This function returns a unique integer every time it is called. It
813 * can be used for any purpose, but is primarily intended to be a unique
814 * index for the iword and pword functions. The expectation is that an
815 * application calls xalloc in order to obtain an index in the iword and
816 * pword arrays that can be used without fear of conflict.
817 *
818 * The implementation maintains a static variable that is incremented and
819 * returned on each invocation. xalloc is guaranteed to return an index
820 * that is safe to use in the iword and pword arrays.
821 */
822 static int
823 xalloc() throw();
824
825 /**
826 * @brief Access to integer array.
827 * @param __ix Index into the array.
828 * @return A reference to an integer associated with the index.
829 *
830 * The iword function provides access to an array of integers that can be
831 * used for any purpose. The array grows as required to hold the
832 * supplied index. All integers in the array are initialized to 0.
833 *
834 * The implementation reserves several indices. You should use xalloc to
835 * obtain an index that is safe to use. Also note that since the array
836 * can grow dynamically, it is not safe to hold onto the reference.
837 */
838 long&
839 iword(int __ix)
840 {
841 _Words& __word = ((unsigned)__ix < (unsigned)_M_word_size)
842 ? _M_word[__ix] : _M_grow_words(__ix, true);
843 return __word._M_iword;
844 }
845
846 /**
847 * @brief Access to void pointer array.
848 * @param __ix Index into the array.
849 * @return A reference to a void* associated with the index.
850 *
851 * The pword function provides access to an array of pointers that can be
852 * used for any purpose. The array grows as required to hold the
853 * supplied index. All pointers in the array are initialized to 0.
854 *
855 * The implementation reserves several indices. You should use xalloc to
856 * obtain an index that is safe to use. Also note that since the array
857 * can grow dynamically, it is not safe to hold onto the reference.
858 */
859 void*&
860 pword(int __ix)
861 {
862 _Words& __word = ((unsigned)__ix < (unsigned)_M_word_size)
863 ? _M_word[__ix] : _M_grow_words(__ix, false);
864 return __word._M_pword;
865 }
866
867 // Destructor
868 /**
869 * Invokes each callback with erase_event. Destroys local storage.
870 *
871 * Note that the ios_base object for the standard streams never gets
872 * destroyed. As a result, any callbacks registered with the standard
873 * streams will not get invoked with erase_event (unless copyfmt is
874 * used).
875 */
876 virtual ~ios_base();
877
878 protected:
879 ios_base() throw ();
880
881 #if __cplusplus < 201103L
882 // _GLIBCXX_RESOLVE_LIB_DEFECTS
883 // 50. Copy constructor and assignment operator of ios_base
884 private:
885 ios_base(const ios_base&);
886
887 ios_base&
888 operator=(const ios_base&);
889 #else
890 public:
891 ios_base(const ios_base&) = delete;
892
893 ios_base&
894 operator=(const ios_base&) = delete;
895
896 protected:
897 void
898 _M_move(ios_base&) noexcept;
899
900 void
901 _M_swap(ios_base& __rhs) noexcept;
902 #endif
903 };
904
905 // [27.4.5.1] fmtflags manipulators
906 /// Calls base.setf(ios_base::boolalpha).
907 inline ios_base&
908 boolalpha(ios_base& __base)
909 {
910 __base.setf(ios_base::boolalpha);
911 return __base;
912 }
913
914 /// Calls base.unsetf(ios_base::boolalpha).
915 inline ios_base&
916 noboolalpha(ios_base& __base)
917 {
918 __base.unsetf(ios_base::boolalpha);
919 return __base;
920 }
921
922 /// Calls base.setf(ios_base::showbase).
923 inline ios_base&
924 showbase(ios_base& __base)
925 {
926 __base.setf(ios_base::showbase);
927 return __base;
928 }
929
930 /// Calls base.unsetf(ios_base::showbase).
931 inline ios_base&
932 noshowbase(ios_base& __base)
933 {
934 __base.unsetf(ios_base::showbase);
935 return __base;
936 }
937
938 /// Calls base.setf(ios_base::showpoint).
939 inline ios_base&
940 showpoint(ios_base& __base)
941 {
942 __base.setf(ios_base::showpoint);
943 return __base;
944 }
945
946 /// Calls base.unsetf(ios_base::showpoint).
947 inline ios_base&
948 noshowpoint(ios_base& __base)
949 {
950 __base.unsetf(ios_base::showpoint);
951 return __base;
952 }
953
954 /// Calls base.setf(ios_base::showpos).
955 inline ios_base&
956 showpos(ios_base& __base)
957 {
958 __base.setf(ios_base::showpos);
959 return __base;
960 }
961
962 /// Calls base.unsetf(ios_base::showpos).
963 inline ios_base&
964 noshowpos(ios_base& __base)
965 {
966 __base.unsetf(ios_base::showpos);
967 return __base;
968 }
969
970 /// Calls base.setf(ios_base::skipws).
971 inline ios_base&
972 skipws(ios_base& __base)
973 {
974 __base.setf(ios_base::skipws);
975 return __base;
976 }
977
978 /// Calls base.unsetf(ios_base::skipws).
979 inline ios_base&
980 noskipws(ios_base& __base)
981 {
982 __base.unsetf(ios_base::skipws);
983 return __base;
984 }
985
986 /// Calls base.setf(ios_base::uppercase).
987 inline ios_base&
988 uppercase(ios_base& __base)
989 {
990 __base.setf(ios_base::uppercase);
991 return __base;
992 }
993
994 /// Calls base.unsetf(ios_base::uppercase).
995 inline ios_base&
996 nouppercase(ios_base& __base)
997 {
998 __base.unsetf(ios_base::uppercase);
999 return __base;
1000 }
1001
1002 /// Calls base.setf(ios_base::unitbuf).
1003 inline ios_base&
1004 unitbuf(ios_base& __base)
1005 {
1006 __base.setf(ios_base::unitbuf);
1007 return __base;
1008 }
1009
1010 /// Calls base.unsetf(ios_base::unitbuf).
1011 inline ios_base&
1012 nounitbuf(ios_base& __base)
1013 {
1014 __base.unsetf(ios_base::unitbuf);
1015 return __base;
1016 }
1017
1018 // [27.4.5.2] adjustfield manipulators
1019 /// Calls base.setf(ios_base::internal, ios_base::adjustfield).
1020 inline ios_base&
1021 internal(ios_base& __base)
1022 {
1023 __base.setf(ios_base::internal, ios_base::adjustfield);
1024 return __base;
1025 }
1026
1027 /// Calls base.setf(ios_base::left, ios_base::adjustfield).
1028 inline ios_base&
1029 left(ios_base& __base)
1030 {
1031 __base.setf(ios_base::left, ios_base::adjustfield);
1032 return __base;
1033 }
1034
1035 /// Calls base.setf(ios_base::right, ios_base::adjustfield).
1036 inline ios_base&
1037 right(ios_base& __base)
1038 {
1039 __base.setf(ios_base::right, ios_base::adjustfield);
1040 return __base;
1041 }
1042
1043 // [27.4.5.3] basefield manipulators
1044 /// Calls base.setf(ios_base::dec, ios_base::basefield).
1045 inline ios_base&
1046 dec(ios_base& __base)
1047 {
1048 __base.setf(ios_base::dec, ios_base::basefield);
1049 return __base;
1050 }
1051
1052 /// Calls base.setf(ios_base::hex, ios_base::basefield).
1053 inline ios_base&
1054 hex(ios_base& __base)
1055 {
1056 __base.setf(ios_base::hex, ios_base::basefield);
1057 return __base;
1058 }
1059
1060 /// Calls base.setf(ios_base::oct, ios_base::basefield).
1061 inline ios_base&
1062 oct(ios_base& __base)
1063 {
1064 __base.setf(ios_base::oct, ios_base::basefield);
1065 return __base;
1066 }
1067
1068 // [27.4.5.4] floatfield manipulators
1069 /// Calls base.setf(ios_base::fixed, ios_base::floatfield).
1070 inline ios_base&
1071 fixed(ios_base& __base)
1072 {
1073 __base.setf(ios_base::fixed, ios_base::floatfield);
1074 return __base;
1075 }
1076
1077 /// Calls base.setf(ios_base::scientific, ios_base::floatfield).
1078 inline ios_base&
1079 scientific(ios_base& __base)
1080 {
1081 __base.setf(ios_base::scientific, ios_base::floatfield);
1082 return __base;
1083 }
1084
1085 #if __cplusplus >= 201103L
1086 // New C++11 floatfield manipulators
1087
1088 /// Calls
1089 /// base.setf(ios_base::fixed|ios_base::scientific, ios_base::floatfield)
1090 inline ios_base&
1091 hexfloat(ios_base& __base)
1092 {
1093 __base.setf(ios_base::fixed | ios_base::scientific, ios_base::floatfield);
1094 return __base;
1095 }
1096
1097 /// Calls @c base.unsetf(ios_base::floatfield)
1098 inline ios_base&
1099 defaultfloat(ios_base& __base)
1100 {
1101 __base.unsetf(ios_base::floatfield);
1102 return __base;
1103 }
1104 #endif
1105
1106 _GLIBCXX_END_NAMESPACE_VERSION
1107 } // namespace
1108
1109 #endif /* _IOS_BASE_H */
1110