1// Iostreams base classes -*- C++ -*-
2
3// Copyright (C) 1997-2022 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
49namespace 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_noreplace = 1L << 6,
120 _S_ios_openmode_end = 1L << 16,
121 _S_ios_openmode_max = __INT_MAX__,
122 _S_ios_openmode_min = ~__INT_MAX__
123 };
124
125 inline _GLIBCXX_CONSTEXPR _Ios_Openmode
126 operator&(_Ios_Openmode __a, _Ios_Openmode __b)
127 { return _Ios_Openmode(static_cast<int>(__a) & static_cast<int>(__b)); }
128
129 inline _GLIBCXX_CONSTEXPR _Ios_Openmode
130 operator|(_Ios_Openmode __a, _Ios_Openmode __b)
131 { return _Ios_Openmode(static_cast<int>(__a) | static_cast<int>(__b)); }
132
133 inline _GLIBCXX_CONSTEXPR _Ios_Openmode
134 operator^(_Ios_Openmode __a, _Ios_Openmode __b)
135 { return _Ios_Openmode(static_cast<int>(__a) ^ static_cast<int>(__b)); }
136
137 inline _GLIBCXX_CONSTEXPR _Ios_Openmode
138 operator~(_Ios_Openmode __a)
139 { return _Ios_Openmode(~static_cast<int>(__a)); }
140
141 inline const _Ios_Openmode&
142 operator|=(_Ios_Openmode& __a, _Ios_Openmode __b)
143 { return __a = __a | __b; }
144
145 inline const _Ios_Openmode&
146 operator&=(_Ios_Openmode& __a, _Ios_Openmode __b)
147 { return __a = __a & __b; }
148
149 inline const _Ios_Openmode&
150 operator^=(_Ios_Openmode& __a, _Ios_Openmode __b)
151 { return __a = __a ^ __b; }
152
153
154 enum _Ios_Iostate
155 {
156 _S_goodbit = 0,
157 _S_badbit = 1L << 0,
158 _S_eofbit = 1L << 1,
159 _S_failbit = 1L << 2,
160 _S_ios_iostate_end = 1L << 16,
161 _S_ios_iostate_max = __INT_MAX__,
162 _S_ios_iostate_min = ~__INT_MAX__
163 };
164
165 inline _GLIBCXX_CONSTEXPR _Ios_Iostate
166 operator&(_Ios_Iostate __a, _Ios_Iostate __b)
167 { return _Ios_Iostate(static_cast<int>(__a) & static_cast<int>(__b)); }
168
169 inline _GLIBCXX_CONSTEXPR _Ios_Iostate
170 operator|(_Ios_Iostate __a, _Ios_Iostate __b)
171 { return _Ios_Iostate(static_cast<int>(__a) | static_cast<int>(__b)); }
172
173 inline _GLIBCXX_CONSTEXPR _Ios_Iostate
174 operator^(_Ios_Iostate __a, _Ios_Iostate __b)
175 { return _Ios_Iostate(static_cast<int>(__a) ^ static_cast<int>(__b)); }
176
177 inline _GLIBCXX_CONSTEXPR _Ios_Iostate
178 operator~(_Ios_Iostate __a)
179 { return _Ios_Iostate(~static_cast<int>(__a)); }
180
181 inline const _Ios_Iostate&
182 operator|=(_Ios_Iostate& __a, _Ios_Iostate __b)
183 { return __a = __a | __b; }
184
185 inline const _Ios_Iostate&
186 operator&=(_Ios_Iostate& __a, _Ios_Iostate __b)
187 { return __a = __a & __b; }
188
189 inline const _Ios_Iostate&
190 operator^=(_Ios_Iostate& __a, _Ios_Iostate __b)
191 { return __a = __a ^ __b; }
192
193
194 enum _Ios_Seekdir
195 {
196 _S_beg = 0,
197 _S_cur = _GLIBCXX_STDIO_SEEK_CUR,
198 _S_end = _GLIBCXX_STDIO_SEEK_END,
199 _S_ios_seekdir_end = 1L << 16
200 };
201
202#if __cplusplus >= 201103L
203 /// I/O error code
204 enum class io_errc { stream = 1 };
205
206 template <> struct is_error_code_enum<io_errc> : public true_type { };
207
208 const error_category& iostream_category() noexcept;
209
210 inline error_code
211 make_error_code(io_errc __e) noexcept
212 { return error_code(static_cast<int>(__e), iostream_category()); }
213
214 inline error_condition
215 make_error_condition(io_errc __e) noexcept
216 { return error_condition(static_cast<int>(__e), iostream_category()); }
217#endif
218
219 // 27.4.2 Class ios_base
220 /**
221 * @brief The base of the I/O class hierarchy.
222 * @ingroup io
223 *
224 * This class defines everything that can be defined about I/O that does
225 * not depend on the type of characters being input or output. Most
226 * people will only see @c ios_base when they need to specify the full
227 * name of the various I/O flags (e.g., the openmodes).
228 */
229 class ios_base
230 {
231#if _GLIBCXX_USE_CXX11_ABI
232#if __cplusplus < 201103L
233 // Type that is layout-compatible with std::system_error
234 struct system_error : std::runtime_error
235 {
236 // Type that is layout-compatible with std::error_code
237 struct error_code
238 {
239 error_code() { }
240 private:
241 int _M_value;
242 const void* _M_cat;
243 } _M_code;
244 };
245#endif
246#endif
247 public:
248
249 /**
250 * @brief These are thrown to indicate problems with io.
251 * @ingroup exceptions
252 *
253 * 27.4.2.1.1 Class ios_base::failure
254 */
255#if _GLIBCXX_USE_CXX11_ABI
256 class _GLIBCXX_ABI_TAG_CXX11 failure : public system_error
257 {
258 public:
259 explicit
260 failure(const string& __str);
261
262#if __cplusplus >= 201103L
263 explicit
264 failure(const string&, const error_code&);
265
266 explicit
267 failure(const char*, const error_code& = io_errc::stream);
268#endif
269
270 virtual
271 ~failure() throw();
272
273 virtual const char*
274 what() const throw();
275 };
276#else
277 class failure : public exception
278 {
279 public:
280 // _GLIBCXX_RESOLVE_LIB_DEFECTS
281 // 48. Use of non-existent exception constructor
282 explicit
283 failure(const string& __str) throw();
284
285 // This declaration is not useless:
286 // http://gcc.gnu.org/onlinedocs/gcc-4.3.2/gcc/Vague-Linkage.html
287 virtual
288 ~failure() throw();
289
290 virtual const char*
291 what() const throw();
292
293#if __cplusplus >= 201103L
294 // Define the new members required by C++11,
295 // even though the error_code cannot be stored.
296
297 explicit
298 failure(const string& __s, const error_code&) noexcept
299 : failure(__s)
300 { }
301
302 explicit
303 failure(const char* __s, const error_code& = error_code{})
304 : failure(string(__s))
305 { }
306
307 // Stand-in for system_error::code() but returning by value.
308 error_code code() const noexcept { return error_code{}; }
309#endif
310
311 private:
312 string _M_msg;
313 };
314#endif
315
316 // 27.4.2.1.2 Type ios_base::fmtflags
317 /**
318 * @brief This is a bitmask type.
319 *
320 * @c @a _Ios_Fmtflags is implementation-defined, but it is valid to
321 * perform bitwise operations on these values and expect the Right
322 * Thing to happen. Defined objects of type fmtflags are:
323 * - boolalpha
324 * - dec
325 * - fixed
326 * - hex
327 * - internal
328 * - left
329 * - oct
330 * - right
331 * - scientific
332 * - showbase
333 * - showpoint
334 * - showpos
335 * - skipws
336 * - unitbuf
337 * - uppercase
338 * - adjustfield
339 * - basefield
340 * - floatfield
341 */
342 typedef _Ios_Fmtflags fmtflags;
343
344 /// Insert/extract @c bool in alphabetic rather than numeric format.
345 static const fmtflags boolalpha = _S_boolalpha;
346
347 /// Converts integer input or generates integer output in decimal base.
348 static const fmtflags dec = _S_dec;
349
350 /// Generate floating-point output in fixed-point notation.
351 static const fmtflags fixed = _S_fixed;
352
353 /// Converts integer input or generates integer output in hexadecimal base.
354 static const fmtflags hex = _S_hex;
355
356 /// Adds fill characters at a designated internal point in certain
357 /// generated output, or identical to @c right if no such point is
358 /// designated.
359 static const fmtflags internal = _S_internal;
360
361 /// Adds fill characters on the right (final positions) of certain
362 /// generated output. (I.e., the thing you print is flush left.)
363 static const fmtflags left = _S_left;
364
365 /// Converts integer input or generates integer output in octal base.
366 static const fmtflags oct = _S_oct;
367
368 /// Adds fill characters on the left (initial positions) of certain
369 /// generated output. (I.e., the thing you print is flush right.)
370 static const fmtflags right = _S_right;
371
372 /// Generates floating-point output in scientific notation.
373 static const fmtflags scientific = _S_scientific;
374
375 /// Generates a prefix indicating the numeric base of generated integer
376 /// output.
377 static const fmtflags showbase = _S_showbase;
378
379 /// Generates a decimal-point character unconditionally in generated
380 /// floating-point output.
381 static const fmtflags showpoint = _S_showpoint;
382
383 /// Generates a + sign in non-negative generated numeric output.
384 static const fmtflags showpos = _S_showpos;
385
386 /// Skips leading white space before certain input operations.
387 static const fmtflags skipws = _S_skipws;
388
389 /// Flushes output after each output operation.
390 static const fmtflags unitbuf = _S_unitbuf;
391
392 /// Replaces certain lowercase letters with their uppercase equivalents
393 /// in generated output.
394 static const fmtflags uppercase = _S_uppercase;
395
396 /// A mask of left|right|internal. Useful for the 2-arg form of @c setf.
397 static const fmtflags adjustfield = _S_adjustfield;
398
399 /// A mask of dec|oct|hex. Useful for the 2-arg form of @c setf.
400 static const fmtflags basefield = _S_basefield;
401
402 /// A mask of scientific|fixed. Useful for the 2-arg form of @c setf.
403 static const fmtflags floatfield = _S_floatfield;
404
405 // 27.4.2.1.3 Type ios_base::iostate
406 /**
407 * @brief This is a bitmask type.
408 *
409 * @c @a _Ios_Iostate is implementation-defined, but it is valid to
410 * perform bitwise operations on these values and expect the Right
411 * Thing to happen. Defined objects of type iostate are:
412 * - badbit
413 * - eofbit
414 * - failbit
415 * - goodbit
416 */
417 typedef _Ios_Iostate iostate;
418
419 /// Indicates a loss of integrity in an input or output sequence (such
420 /// as an irrecoverable read error from a file).
421 static const iostate badbit = _S_badbit;
422
423 /// Indicates that an input operation reached the end of an input sequence.
424 static const iostate eofbit = _S_eofbit;
425
426 /// Indicates that an input operation failed to read the expected
427 /// characters, or that an output operation failed to generate the
428 /// desired characters.
429 static const iostate failbit = _S_failbit;
430
431 /// Indicates all is well.
432 static const iostate goodbit = _S_goodbit;
433
434 // 27.4.2.1.4 Type ios_base::openmode
435 /**
436 * @brief This is a bitmask type.
437 *
438 * @c @a _Ios_Openmode is implementation-defined, but it is valid to
439 * perform bitwise operations on these values and expect the Right
440 * Thing to happen. Defined objects of type openmode are:
441 * - app
442 * - ate
443 * - binary
444 * - in
445 * - out
446 * - trunc
447 */
448 typedef _Ios_Openmode openmode;
449
450 /// Seek to end before each write.
451 static const openmode app = _S_app;
452
453 /// Open and seek to end immediately after opening.
454 static const openmode ate = _S_ate;
455
456 /// Perform input and output in binary mode (as opposed to text mode).
457 /// This is probably not what you think it is; see
458 /// https://gcc.gnu.org/onlinedocs/libstdc++/manual/fstreams.html#std.io.filestreams.binary
459 static const openmode binary = _S_bin;
460
461 /// Open for input. Default for @c ifstream and fstream.
462 static const openmode in = _S_in;
463
464 /// Open for output. Default for @c ofstream and fstream.
465 static const openmode out = _S_out;
466
467 /// Truncate an existing stream when opening. Default for @c ofstream.
468 static const openmode trunc = _S_trunc;
469
470 static const openmode __noreplace = _S_noreplace;
471
472#if __cplusplus >= 202100L
473#define __cpp_lib_ios_noreplace 202207L
474 /// Open a file in exclusive mode.
475 static const openmode noreplace = _S_noreplace;
476#endif
477
478 // 27.4.2.1.5 Type ios_base::seekdir
479 /**
480 * @brief This is an enumerated type.
481 *
482 * @c @a _Ios_Seekdir is implementation-defined. Defined values
483 * of type seekdir are:
484 * - beg
485 * - cur, equivalent to @c SEEK_CUR in the C standard library.
486 * - end, equivalent to @c SEEK_END in the C standard library.
487 */
488 typedef _Ios_Seekdir seekdir;
489
490 /// Request a seek relative to the beginning of the stream.
491 static const seekdir beg = _S_beg;
492
493 /// Request a seek relative to the current position within the sequence.
494 static const seekdir cur = _S_cur;
495
496 /// Request a seek relative to the current end of the sequence.
497 static const seekdir end = _S_end;
498
499#if __cplusplus <= 201402L
500 // Annex D.6 (removed in C++17)
501 typedef int io_state
502 _GLIBCXX_DEPRECATED_SUGGEST("std::iostate");
503 typedef int open_mode
504 _GLIBCXX_DEPRECATED_SUGGEST("std::openmode");
505 typedef int seek_dir
506 _GLIBCXX_DEPRECATED_SUGGEST("std::seekdir");
507
508 typedef std::streampos streampos
509 _GLIBCXX_DEPRECATED_SUGGEST("std::streampos");
510 typedef std::streamoff streamoff
511 _GLIBCXX_DEPRECATED_SUGGEST("std::streamoff");
512#endif
513
514 // Callbacks;
515 /**
516 * @brief The set of events that may be passed to an event callback.
517 *
518 * erase_event is used during ~ios() and copyfmt(). imbue_event is used
519 * during imbue(). copyfmt_event is used during copyfmt().
520 */
521 enum event
522 {
523 erase_event,
524 imbue_event,
525 copyfmt_event
526 };
527
528 /**
529 * @brief The type of an event callback function.
530 * @param __e One of the members of the event enum.
531 * @param __b Reference to the ios_base object.
532 * @param __i The integer provided when the callback was registered.
533 *
534 * Event callbacks are user defined functions that get called during
535 * several ios_base and basic_ios functions, specifically imbue(),
536 * copyfmt(), and ~ios().
537 */
538 typedef void (*event_callback) (event __e, ios_base& __b, int __i);
539
540 /**
541 * @brief Add the callback __fn with parameter __index.
542 * @param __fn The function to add.
543 * @param __index The integer to pass to the function when invoked.
544 *
545 * Registers a function as an event callback with an integer parameter to
546 * be passed to the function when invoked. Multiple copies of the
547 * function are allowed. If there are multiple callbacks, they are
548 * invoked in the order they were registered.
549 */
550 void
551 register_callback(event_callback __fn, int __index);
552
553 protected:
554 streamsize _M_precision;
555 streamsize _M_width;
556 fmtflags _M_flags;
557 iostate _M_exception;
558 iostate _M_streambuf_state;
559
560 // 27.4.2.6 Members for callbacks
561 // 27.4.2.6 ios_base callbacks
562 struct _Callback_list
563 {
564 // Data Members
565 _Callback_list* _M_next;
566 ios_base::event_callback _M_fn;
567 int _M_index;
568 _Atomic_word _M_refcount; // 0 means one reference.
569
570 _Callback_list(ios_base::event_callback __fn, int __index,
571 _Callback_list* __cb)
572 : _M_next(__cb), _M_fn(__fn), _M_index(__index), _M_refcount(0) { }
573
574 void
575 _M_add_reference() { __gnu_cxx::__atomic_add_dispatch(&_M_refcount, 1); }
576
577 // 0 => OK to delete.
578 int
579 _M_remove_reference()
580 {
581 // Be race-detector-friendly. For more info see bits/c++config.
582 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount);
583 int __res = __gnu_cxx::__exchange_and_add_dispatch(&_M_refcount, -1);
584 if (__res == 0)
585 {
586 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount);
587 }
588 return __res;
589 }
590 };
591
592 _Callback_list* _M_callbacks;
593
594 void
595 _M_call_callbacks(event __ev) throw();
596
597 void
598 _M_dispose_callbacks(void) throw();
599
600 // 27.4.2.5 Members for iword/pword storage
601 struct _Words
602 {
603 void* _M_pword;
604 long _M_iword;
605 _Words() : _M_pword(0), _M_iword(0) { }
606 };
607
608 // Only for failed iword/pword calls.
609 _Words _M_word_zero;
610
611 // Guaranteed storage.
612 // The first 5 iword and pword slots are reserved for internal use.
613 enum { _S_local_word_size = 8 };
614 _Words _M_local_word[_S_local_word_size];
615
616 // Allocated storage.
617 int _M_word_size;
618 _Words* _M_word;
619
620 _Words&
621 _M_grow_words(int __index, bool __iword);
622
623 // Members for locale and locale caching.
624 locale _M_ios_locale;
625
626 void
627 _M_init() throw();
628
629 public:
630
631 // 27.4.2.1.6 Class ios_base::Init
632 // Used to initialize standard streams. In theory, g++ could use
633 // -finit-priority to order this stuff correctly without going
634 // through these machinations.
635 class Init
636 {
637 friend class ios_base;
638 public:
639 Init();
640 ~Init();
641
642#if __cplusplus >= 201103L
643 Init(const Init&) = default;
644 Init& operator=(const Init&) = default;
645#endif
646
647 private:
648 static _Atomic_word _S_refcount;
649 static bool _S_synced_with_stdio;
650 };
651
652 // [27.4.2.2] fmtflags state functions
653 /**
654 * @brief Access to format flags.
655 * @return The format control flags for both input and output.
656 */
657 fmtflags
658 flags() const
659 { return _M_flags; }
660
661 /**
662 * @brief Setting new format flags all at once.
663 * @param __fmtfl The new flags to set.
664 * @return The previous format control flags.
665 *
666 * This function overwrites all the format flags with @a __fmtfl.
667 */
668 fmtflags
669 flags(fmtflags __fmtfl)
670 {
671 fmtflags __old = _M_flags;
672 _M_flags = __fmtfl;
673 return __old;
674 }
675
676 /**
677 * @brief Setting new format flags.
678 * @param __fmtfl Additional flags to set.
679 * @return The previous format control flags.
680 *
681 * This function sets additional flags in format control. Flags that
682 * were previously set remain set.
683 */
684 fmtflags
685 setf(fmtflags __fmtfl)
686 {
687 fmtflags __old = _M_flags;
688 _M_flags |= __fmtfl;
689 return __old;
690 }
691
692 /**
693 * @brief Setting new format flags.
694 * @param __fmtfl Additional flags to set.
695 * @param __mask The flags mask for @a fmtfl.
696 * @return The previous format control flags.
697 *
698 * This function clears @a mask in the format flags, then sets
699 * @a fmtfl @c & @a mask. An example mask is @c ios_base::adjustfield.
700 */
701 fmtflags
702 setf(fmtflags __fmtfl, fmtflags __mask)
703 {
704 fmtflags __old = _M_flags;
705 _M_flags &= ~__mask;
706 _M_flags |= (__fmtfl & __mask);
707 return __old;
708 }
709
710 /**
711 * @brief Clearing format flags.
712 * @param __mask The flags to unset.
713 *
714 * This function clears @a __mask in the format flags.
715 */
716 void
717 unsetf(fmtflags __mask)
718 { _M_flags &= ~__mask; }
719
720 /**
721 * @brief Flags access.
722 * @return The precision to generate on certain output operations.
723 *
724 * Be careful if you try to give a definition of @a precision here; see
725 * DR 189.
726 */
727 streamsize
728 precision() const
729 { return _M_precision; }
730
731 /**
732 * @brief Changing flags.
733 * @param __prec The new precision value.
734 * @return The previous value of precision().
735 */
736 streamsize
737 precision(streamsize __prec)
738 {
739 streamsize __old = _M_precision;
740 _M_precision = __prec;
741 return __old;
742 }
743
744 /**
745 * @brief Flags access.
746 * @return The minimum field width to generate on output operations.
747 *
748 * <em>Minimum field width</em> refers to the number of characters.
749 */
750 streamsize
751 width() const
752 { return _M_width; }
753
754 /**
755 * @brief Changing flags.
756 * @param __wide The new width value.
757 * @return The previous value of width().
758 */
759 streamsize
760 width(streamsize __wide)
761 {
762 streamsize __old = _M_width;
763 _M_width = __wide;
764 return __old;
765 }
766
767 // [27.4.2.4] ios_base static members
768 /**
769 * @brief Interaction with the standard C I/O objects.
770 * @param __sync Whether to synchronize or not.
771 * @return True if the standard streams were previously synchronized.
772 *
773 * The synchronization referred to is @e only that between the standard
774 * C facilities (e.g., stdout) and the standard C++ objects (e.g.,
775 * cout). User-declared streams are unaffected. See
776 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/fstreams.html#std.io.filestreams.binary
777 */
778 static bool
779 sync_with_stdio(bool __sync = true);
780
781 // [27.4.2.3] ios_base locale functions
782 /**
783 * @brief Setting a new locale.
784 * @param __loc The new locale.
785 * @return The previous locale.
786 *
787 * Sets the new locale for this stream, and then invokes each callback
788 * with imbue_event.
789 */
790 locale
791 imbue(const locale& __loc) throw();
792
793 /**
794 * @brief Locale access
795 * @return A copy of the current locale.
796 *
797 * If @c imbue(loc) has previously been called, then this function
798 * returns @c loc. Otherwise, it returns a copy of @c std::locale(),
799 * the global C++ locale.
800 */
801 locale
802 getloc() const
803 { return _M_ios_locale; }
804
805 /**
806 * @brief Locale access
807 * @return A reference to the current locale.
808 *
809 * Like getloc above, but returns a reference instead of
810 * generating a copy.
811 */
812 const locale&
813 _M_getloc() const
814 { return _M_ios_locale; }
815
816 // [27.4.2.5] ios_base storage functions
817 /**
818 * @brief Access to unique indices.
819 * @return An integer different from all previous calls.
820 *
821 * This function returns a unique integer every time it is called. It
822 * can be used for any purpose, but is primarily intended to be a unique
823 * index for the iword and pword functions. The expectation is that an
824 * application calls xalloc in order to obtain an index in the iword and
825 * pword arrays that can be used without fear of conflict.
826 *
827 * The implementation maintains a static variable that is incremented and
828 * returned on each invocation. xalloc is guaranteed to return an index
829 * that is safe to use in the iword and pword arrays.
830 */
831 static int
832 xalloc() throw();
833
834 /**
835 * @brief Access to integer array.
836 * @param __ix Index into the array.
837 * @return A reference to an integer associated with the index.
838 *
839 * The iword function provides access to an array of integers that can be
840 * used for any purpose. The array grows as required to hold the
841 * supplied index. All integers in the array are initialized to 0.
842 *
843 * The implementation reserves several indices. You should use xalloc to
844 * obtain an index that is safe to use. Also note that since the array
845 * can grow dynamically, it is not safe to hold onto the reference.
846 */
847 long&
848 iword(int __ix)
849 {
850 _Words& __word = ((unsigned)__ix < (unsigned)_M_word_size)
851 ? _M_word[__ix] : _M_grow_words(__ix, true);
852 return __word._M_iword;
853 }
854
855 /**
856 * @brief Access to void pointer array.
857 * @param __ix Index into the array.
858 * @return A reference to a void* associated with the index.
859 *
860 * The pword function provides access to an array of pointers that can be
861 * used for any purpose. The array grows as required to hold the
862 * supplied index. All pointers in the array are initialized to 0.
863 *
864 * The implementation reserves several indices. You should use xalloc to
865 * obtain an index that is safe to use. Also note that since the array
866 * can grow dynamically, it is not safe to hold onto the reference.
867 */
868 void*&
869 pword(int __ix)
870 {
871 _Words& __word = ((unsigned)__ix < (unsigned)_M_word_size)
872 ? _M_word[__ix] : _M_grow_words(__ix, false);
873 return __word._M_pword;
874 }
875
876 // Destructor
877 /**
878 * Invokes each callback with erase_event. Destroys local storage.
879 *
880 * Note that the ios_base object for the standard streams never gets
881 * destroyed. As a result, any callbacks registered with the standard
882 * streams will not get invoked with erase_event (unless copyfmt is
883 * used).
884 */
885 virtual ~ios_base();
886
887 protected:
888 ios_base() throw ();
889
890#if __cplusplus < 201103L
891 // _GLIBCXX_RESOLVE_LIB_DEFECTS
892 // 50. Copy constructor and assignment operator of ios_base
893 private:
894 ios_base(const ios_base&);
895
896 ios_base&
897 operator=(const ios_base&);
898#else
899 public:
900 ios_base(const ios_base&) = delete;
901
902 ios_base&
903 operator=(const ios_base&) = delete;
904
905 protected:
906 void
907 _M_move(ios_base&) noexcept;
908
909 void
910 _M_swap(ios_base& __rhs) noexcept;
911#endif
912 };
913
914 // [27.4.5.1] fmtflags manipulators
915 /// Calls base.setf(ios_base::boolalpha).
916 inline ios_base&
917 boolalpha(ios_base& __base)
918 {
919 __base.setf(ios_base::boolalpha);
920 return __base;
921 }
922
923 /// Calls base.unsetf(ios_base::boolalpha).
924 inline ios_base&
925 noboolalpha(ios_base& __base)
926 {
927 __base.unsetf(ios_base::boolalpha);
928 return __base;
929 }
930
931 /// Calls base.setf(ios_base::showbase).
932 inline ios_base&
933 showbase(ios_base& __base)
934 {
935 __base.setf(ios_base::showbase);
936 return __base;
937 }
938
939 /// Calls base.unsetf(ios_base::showbase).
940 inline ios_base&
941 noshowbase(ios_base& __base)
942 {
943 __base.unsetf(ios_base::showbase);
944 return __base;
945 }
946
947 /// Calls base.setf(ios_base::showpoint).
948 inline ios_base&
949 showpoint(ios_base& __base)
950 {
951 __base.setf(ios_base::showpoint);
952 return __base;
953 }
954
955 /// Calls base.unsetf(ios_base::showpoint).
956 inline ios_base&
957 noshowpoint(ios_base& __base)
958 {
959 __base.unsetf(ios_base::showpoint);
960 return __base;
961 }
962
963 /// Calls base.setf(ios_base::showpos).
964 inline ios_base&
965 showpos(ios_base& __base)
966 {
967 __base.setf(ios_base::showpos);
968 return __base;
969 }
970
971 /// Calls base.unsetf(ios_base::showpos).
972 inline ios_base&
973 noshowpos(ios_base& __base)
974 {
975 __base.unsetf(ios_base::showpos);
976 return __base;
977 }
978
979 /// Calls base.setf(ios_base::skipws).
980 inline ios_base&
981 skipws(ios_base& __base)
982 {
983 __base.setf(ios_base::skipws);
984 return __base;
985 }
986
987 /// Calls base.unsetf(ios_base::skipws).
988 inline ios_base&
989 noskipws(ios_base& __base)
990 {
991 __base.unsetf(ios_base::skipws);
992 return __base;
993 }
994
995 /// Calls base.setf(ios_base::uppercase).
996 inline ios_base&
997 uppercase(ios_base& __base)
998 {
999 __base.setf(ios_base::uppercase);
1000 return __base;
1001 }
1002
1003 /// Calls base.unsetf(ios_base::uppercase).
1004 inline ios_base&
1005 nouppercase(ios_base& __base)
1006 {
1007 __base.unsetf(ios_base::uppercase);
1008 return __base;
1009 }
1010
1011 /// Calls base.setf(ios_base::unitbuf).
1012 inline ios_base&
1013 unitbuf(ios_base& __base)
1014 {
1015 __base.setf(ios_base::unitbuf);
1016 return __base;
1017 }
1018
1019 /// Calls base.unsetf(ios_base::unitbuf).
1020 inline ios_base&
1021 nounitbuf(ios_base& __base)
1022 {
1023 __base.unsetf(ios_base::unitbuf);
1024 return __base;
1025 }
1026
1027 // [27.4.5.2] adjustfield manipulators
1028 /// Calls base.setf(ios_base::internal, ios_base::adjustfield).
1029 inline ios_base&
1030 internal(ios_base& __base)
1031 {
1032 __base.setf(ios_base::internal, ios_base::adjustfield);
1033 return __base;
1034 }
1035
1036 /// Calls base.setf(ios_base::left, ios_base::adjustfield).
1037 inline ios_base&
1038 left(ios_base& __base)
1039 {
1040 __base.setf(ios_base::left, ios_base::adjustfield);
1041 return __base;
1042 }
1043
1044 /// Calls base.setf(ios_base::right, ios_base::adjustfield).
1045 inline ios_base&
1046 right(ios_base& __base)
1047 {
1048 __base.setf(ios_base::right, ios_base::adjustfield);
1049 return __base;
1050 }
1051
1052 // [27.4.5.3] basefield manipulators
1053 /// Calls base.setf(ios_base::dec, ios_base::basefield).
1054 inline ios_base&
1055 dec(ios_base& __base)
1056 {
1057 __base.setf(ios_base::dec, ios_base::basefield);
1058 return __base;
1059 }
1060
1061 /// Calls base.setf(ios_base::hex, ios_base::basefield).
1062 inline ios_base&
1063 hex(ios_base& __base)
1064 {
1065 __base.setf(ios_base::hex, ios_base::basefield);
1066 return __base;
1067 }
1068
1069 /// Calls base.setf(ios_base::oct, ios_base::basefield).
1070 inline ios_base&
1071 oct(ios_base& __base)
1072 {
1073 __base.setf(ios_base::oct, ios_base::basefield);
1074 return __base;
1075 }
1076
1077 // [27.4.5.4] floatfield manipulators
1078 /// Calls base.setf(ios_base::fixed, ios_base::floatfield).
1079 inline ios_base&
1080 fixed(ios_base& __base)
1081 {
1082 __base.setf(ios_base::fixed, ios_base::floatfield);
1083 return __base;
1084 }
1085
1086 /// Calls base.setf(ios_base::scientific, ios_base::floatfield).
1087 inline ios_base&
1088 scientific(ios_base& __base)
1089 {
1090 __base.setf(ios_base::scientific, ios_base::floatfield);
1091 return __base;
1092 }
1093
1094#if __cplusplus >= 201103L
1095 // New C++11 floatfield manipulators
1096
1097 /// Calls
1098 /// base.setf(ios_base::fixed|ios_base::scientific, ios_base::floatfield)
1099 inline ios_base&
1100 hexfloat(ios_base& __base)
1101 {
1102 __base.setf(ios_base::fixed | ios_base::scientific, ios_base::floatfield);
1103 return __base;
1104 }
1105
1106 /// Calls @c base.unsetf(ios_base::floatfield)
1107 inline ios_base&
1108 defaultfloat(ios_base& __base)
1109 {
1110 __base.unsetf(ios_base::floatfield);
1111 return __base;
1112 }
1113#endif
1114
1115_GLIBCXX_END_NAMESPACE_VERSION
1116} // namespace
1117
1118#endif /* _IOS_BASE_H */
1119