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 
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_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 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 typedef int open_mode; 
476 typedef int seek_dir; 
477 
478 typedef std::streampos streampos; 
479 typedef std::streamoff streamoff; 
480#endif 
481 
482 // Callbacks; 
483 /** 
484 * @brief The set of events that may be passed to an event callback. 
485 * 
486 * erase_event is used during ~ios() and copyfmt(). imbue_event is used 
487 * during imbue(). copyfmt_event is used during copyfmt(). 
488 */ 
489 enum event 
490 { 
491 erase_event, 
492 imbue_event, 
493 copyfmt_event 
494 }; 
495 
496 /** 
497 * @brief The type of an event callback function. 
498 * @param __e One of the members of the event enum. 
499 * @param __b Reference to the ios_base object. 
500 * @param __i The integer provided when the callback was registered. 
501 * 
502 * Event callbacks are user defined functions that get called during 
503 * several ios_base and basic_ios functions, specifically imbue(), 
504 * copyfmt(), and ~ios(). 
505 */ 
506 typedef void (*event_callback) (event __e, ios_base& __b, int __i); 
507 
508 /** 
509 * @brief Add the callback __fn with parameter __index. 
510 * @param __fn The function to add. 
511 * @param __index The integer to pass to the function when invoked. 
512 * 
513 * Registers a function as an event callback with an integer parameter to 
514 * be passed to the function when invoked. Multiple copies of the 
515 * function are allowed. If there are multiple callbacks, they are 
516 * invoked in the order they were registered. 
517 */ 
518 void 
519 register_callback(event_callback __fn, int __index); 
520 
521 protected: 
522 streamsize _M_precision; 
523 streamsize _M_width; 
524 fmtflags _M_flags; 
525 iostate _M_exception; 
526 iostate _M_streambuf_state; 
527 
528 // 27.4.2.6 Members for callbacks 
529 // 27.4.2.6 ios_base callbacks 
530 struct _Callback_list 
531 { 
532 // Data Members 
533 _Callback_list* _M_next; 
534 ios_base::event_callback _M_fn; 
535 int _M_index; 
536 _Atomic_word _M_refcount; // 0 means one reference. 
537 
538 _Callback_list(ios_base::event_callback __fn, int __index, 
539 _Callback_list* __cb) 
540 : _M_next(__cb), _M_fn(__fn), _M_index(__index), _M_refcount(0) { } 
541 
542 void 
543 _M_add_reference() { __gnu_cxx::__atomic_add_dispatch(&_M_refcount, 1); } 
544 
545 // 0 => OK to delete. 
546 int 
547 _M_remove_reference()  
548 { 
549 // Be race-detector-friendly. For more info see bits/c++config. 
550 _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_refcount); 
551 int __res = __gnu_cxx::__exchange_and_add_dispatch(&_M_refcount, -1); 
552 if (__res == 0) 
553 { 
554 _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_refcount); 
555 } 
556 return __res; 
557 } 
558 }; 
559 
560 _Callback_list* _M_callbacks; 
561 
562 void 
563 _M_call_callbacks(event __ev) throw(); 
564 
565 void 
566 _M_dispose_callbacks(void) throw(); 
567 
568 // 27.4.2.5 Members for iword/pword storage 
569 struct _Words 
570 { 
571 void* _M_pword; 
572 long _M_iword; 
573 _Words() : _M_pword(0), _M_iword(0) { } 
574 }; 
575 
576 // Only for failed iword/pword calls. 
577 _Words _M_word_zero; 
578 
579 // Guaranteed storage. 
580 // The first 5 iword and pword slots are reserved for internal use. 
581 enum { _S_local_word_size = 8 }; 
582 _Words _M_local_word[_S_local_word_size]; 
583 
584 // Allocated storage. 
585 int _M_word_size; 
586 _Words* _M_word; 
587 
588 _Words& 
589 _M_grow_words(int __index, bool __iword); 
590 
591 // Members for locale and locale caching. 
592 locale _M_ios_locale; 
593 
594 void 
595 _M_init() throw(); 
596 
597 public: 
598 
599 // 27.4.2.1.6 Class ios_base::Init 
600 // Used to initialize standard streams. In theory, g++ could use 
601 // -finit-priority to order this stuff correctly without going 
602 // through these machinations. 
603 class Init 
604 { 
605 friend class ios_base; 
606 public: 
607 Init(); 
608 ~Init(); 
609 
610#if __cplusplus >= 201103L 
611 Init(const Init&) = default; 
612 Init& operator=(const Init&) = default; 
613#endif 
614 
615 private: 
616 static _Atomic_word _S_refcount; 
617 static bool _S_synced_with_stdio; 
618 }; 
619 
620 // [27.4.2.2] fmtflags state functions 
621 /** 
622 * @brief Access to format flags. 
623 * @return The format control flags for both input and output. 
624 */ 
625 fmtflags 
626 flags() const 
627 { return _M_flags; } 
628 
629 /** 
630 * @brief Setting new format flags all at once. 
631 * @param __fmtfl The new flags to set. 
632 * @return The previous format control flags. 
633 * 
634 * This function overwrites all the format flags with @a __fmtfl. 
635 */ 
636 fmtflags 
637 flags(fmtflags __fmtfl) 
638 { 
639 fmtflags __old = _M_flags; 
640 _M_flags = __fmtfl; 
641 return __old; 
642 } 
643 
644 /** 
645 * @brief Setting new format flags. 
646 * @param __fmtfl Additional flags to set. 
647 * @return The previous format control flags. 
648 * 
649 * This function sets additional flags in format control. Flags that 
650 * were previously set remain set. 
651 */ 
652 fmtflags 
653 setf(fmtflags __fmtfl) 
654 { 
655 fmtflags __old = _M_flags; 
656 _M_flags |= __fmtfl; 
657 return __old; 
658 } 
659 
660 /** 
661 * @brief Setting new format flags. 
662 * @param __fmtfl Additional flags to set. 
663 * @param __mask The flags mask for @a fmtfl. 
664 * @return The previous format control flags. 
665 * 
666 * This function clears @a mask in the format flags, then sets 
667 * @a fmtfl @c & @a mask. An example mask is @c ios_base::adjustfield. 
668 */ 
669 fmtflags 
670 setf(fmtflags __fmtfl, fmtflags __mask) 
671 { 
672 fmtflags __old = _M_flags; 
673 _M_flags &= ~__mask; 
674 _M_flags |= (__fmtfl & __mask); 
675 return __old; 
676 } 
677 
678 /** 
679 * @brief Clearing format flags. 
680 * @param __mask The flags to unset. 
681 * 
682 * This function clears @a __mask in the format flags. 
683 */ 
684 void 
685 unsetf(fmtflags __mask) 
686 { _M_flags &= ~__mask; } 
687 
688 /** 
689 * @brief Flags access. 
690 * @return The precision to generate on certain output operations. 
691 * 
692 * Be careful if you try to give a definition of @a precision here; see 
693 * DR 189. 
694 */ 
695 streamsize 
696 precision() const 
697 { return _M_precision; } 
698 
699 /** 
700 * @brief Changing flags. 
701 * @param __prec The new precision value. 
702 * @return The previous value of precision(). 
703 */ 
704 streamsize 
705 precision(streamsize __prec) 
706 { 
707 streamsize __old = _M_precision; 
708 _M_precision = __prec; 
709 return __old; 
710 } 
711 
712 /** 
713 * @brief Flags access. 
714 * @return The minimum field width to generate on output operations. 
715 * 
716 * <em>Minimum field width</em> refers to the number of characters. 
717 */ 
718 streamsize 
719 width() const 
720 { return _M_width; } 
721 
722 /** 
723 * @brief Changing flags. 
724 * @param __wide The new width value. 
725 * @return The previous value of width(). 
726 */ 
727 streamsize 
728 width(streamsize __wide) 
729 { 
730 streamsize __old = _M_width; 
731 _M_width = __wide; 
732 return __old; 
733 } 
734 
735 // [27.4.2.4] ios_base static members 
736 /** 
737 * @brief Interaction with the standard C I/O objects. 
738 * @param __sync Whether to synchronize or not. 
739 * @return True if the standard streams were previously synchronized. 
740 * 
741 * The synchronization referred to is @e only that between the standard 
742 * C facilities (e.g., stdout) and the standard C++ objects (e.g., 
743 * cout). User-declared streams are unaffected. See 
744 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/fstreams.html#std.io.filestreams.binary 
745 */ 
746 static bool 
747 sync_with_stdio(bool __sync = true); 
748 
749 // [27.4.2.3] ios_base locale functions 
750 /** 
751 * @brief Setting a new locale. 
752 * @param __loc The new locale. 
753 * @return The previous locale. 
754 * 
755 * Sets the new locale for this stream, and then invokes each callback 
756 * with imbue_event. 
757 */ 
758 locale 
759 imbue(const locale& __loc) throw(); 
760 
761 /** 
762 * @brief Locale access 
763 * @return A copy of the current locale. 
764 * 
765 * If @c imbue(loc) has previously been called, then this function 
766 * returns @c loc. Otherwise, it returns a copy of @c std::locale(), 
767 * the global C++ locale. 
768 */ 
769 locale 
770 getloc() const 
771 { return _M_ios_locale; } 
772 
773 /** 
774 * @brief Locale access 
775 * @return A reference to the current locale. 
776 * 
777 * Like getloc above, but returns a reference instead of 
778 * generating a copy. 
779 */ 
780 const locale& 
781 _M_getloc() const 
782 { return _M_ios_locale; } 
783 
784 // [27.4.2.5] ios_base storage functions 
785 /** 
786 * @brief Access to unique indices. 
787 * @return An integer different from all previous calls. 
788 * 
789 * This function returns a unique integer every time it is called. It 
790 * can be used for any purpose, but is primarily intended to be a unique 
791 * index for the iword and pword functions. The expectation is that an 
792 * application calls xalloc in order to obtain an index in the iword and 
793 * pword arrays that can be used without fear of conflict. 
794 * 
795 * The implementation maintains a static variable that is incremented and 
796 * returned on each invocation. xalloc is guaranteed to return an index 
797 * that is safe to use in the iword and pword arrays. 
798 */ 
799 static int 
800 xalloc() throw(); 
801 
802 /** 
803 * @brief Access to integer array. 
804 * @param __ix Index into the array. 
805 * @return A reference to an integer associated with the index. 
806 * 
807 * The iword function provides access to an array of integers that can be 
808 * used for any purpose. The array grows as required to hold the 
809 * supplied index. All integers in the array are initialized to 0. 
810 * 
811 * The implementation reserves several indices. You should use xalloc to 
812 * obtain an index that is safe to use. Also note that since the array 
813 * can grow dynamically, it is not safe to hold onto the reference. 
814 */ 
815 long& 
816 iword(int __ix) 
817 { 
818 _Words& __word = ((unsigned)__ix < (unsigned)_M_word_size) 
819 ? _M_word[__ix] : _M_grow_words(__ix, true); 
820 return __word._M_iword; 
821 } 
822 
823 /** 
824 * @brief Access to void pointer array. 
825 * @param __ix Index into the array. 
826 * @return A reference to a void* associated with the index. 
827 * 
828 * The pword function provides access to an array of pointers that can be 
829 * used for any purpose. The array grows as required to hold the 
830 * supplied index. All pointers in the array are initialized to 0. 
831 * 
832 * The implementation reserves several indices. You should use xalloc to 
833 * obtain an index that is safe to use. Also note that since the array 
834 * can grow dynamically, it is not safe to hold onto the reference. 
835 */ 
836 void*& 
837 pword(int __ix) 
838 { 
839 _Words& __word = ((unsigned)__ix < (unsigned)_M_word_size) 
840 ? _M_word[__ix] : _M_grow_words(__ix, false); 
841 return __word._M_pword; 
842 } 
843 
844 // Destructor 
845 /** 
846 * Invokes each callback with erase_event. Destroys local storage. 
847 * 
848 * Note that the ios_base object for the standard streams never gets 
849 * destroyed. As a result, any callbacks registered with the standard 
850 * streams will not get invoked with erase_event (unless copyfmt is 
851 * used). 
852 */ 
853 virtual ~ios_base(); 
854 
855 protected: 
856 ios_base() throw (); 
857 
858#if __cplusplus < 201103L 
859 // _GLIBCXX_RESOLVE_LIB_DEFECTS 
860 // 50. Copy constructor and assignment operator of ios_base 
861 private: 
862 ios_base(const ios_base&); 
863 
864 ios_base& 
865 operator=(const ios_base&); 
866#else 
867 public: 
868 ios_base(const ios_base&) = delete; 
869 
870 ios_base& 
871 operator=(const ios_base&) = delete; 
872 
873 protected: 
874 void 
875 _M_move(ios_base&) noexcept; 
876 
877 void 
878 _M_swap(ios_base& __rhs) noexcept; 
879#endif 
880 }; 
881 
882 // [27.4.5.1] fmtflags manipulators 
883 /// Calls base.setf(ios_base::boolalpha). 
884 inline ios_base& 
885 boolalpha(ios_base& __base) 
886 { 
887 __base.setf(ios_base::boolalpha); 
888 return __base; 
889 } 
890 
891 /// Calls base.unsetf(ios_base::boolalpha). 
892 inline ios_base& 
893 noboolalpha(ios_base& __base) 
894 { 
895 __base.unsetf(ios_base::boolalpha); 
896 return __base; 
897 } 
898 
899 /// Calls base.setf(ios_base::showbase). 
900 inline ios_base& 
901 showbase(ios_base& __base) 
902 { 
903 __base.setf(ios_base::showbase); 
904 return __base; 
905 } 
906 
907 /// Calls base.unsetf(ios_base::showbase). 
908 inline ios_base& 
909 noshowbase(ios_base& __base) 
910 { 
911 __base.unsetf(ios_base::showbase); 
912 return __base; 
913 } 
914 
915 /// Calls base.setf(ios_base::showpoint). 
916 inline ios_base& 
917 showpoint(ios_base& __base) 
918 { 
919 __base.setf(ios_base::showpoint); 
920 return __base; 
921 } 
922 
923 /// Calls base.unsetf(ios_base::showpoint). 
924 inline ios_base& 
925 noshowpoint(ios_base& __base) 
926 { 
927 __base.unsetf(ios_base::showpoint); 
928 return __base; 
929 } 
930 
931 /// Calls base.setf(ios_base::showpos). 
932 inline ios_base& 
933 showpos(ios_base& __base) 
934 { 
935 __base.setf(ios_base::showpos); 
936 return __base; 
937 } 
938 
939 /// Calls base.unsetf(ios_base::showpos). 
940 inline ios_base& 
941 noshowpos(ios_base& __base) 
942 { 
943 __base.unsetf(ios_base::showpos); 
944 return __base; 
945 } 
946 
947 /// Calls base.setf(ios_base::skipws). 
948 inline ios_base& 
949 skipws(ios_base& __base) 
950 { 
951 __base.setf(ios_base::skipws); 
952 return __base; 
953 } 
954 
955 /// Calls base.unsetf(ios_base::skipws). 
956 inline ios_base& 
957 noskipws(ios_base& __base) 
958 { 
959 __base.unsetf(ios_base::skipws); 
960 return __base; 
961 } 
962 
963 /// Calls base.setf(ios_base::uppercase). 
964 inline ios_base& 
965 uppercase(ios_base& __base) 
966 { 
967 __base.setf(ios_base::uppercase); 
968 return __base; 
969 } 
970 
971 /// Calls base.unsetf(ios_base::uppercase). 
972 inline ios_base& 
973 nouppercase(ios_base& __base) 
974 { 
975 __base.unsetf(ios_base::uppercase); 
976 return __base; 
977 } 
978 
979 /// Calls base.setf(ios_base::unitbuf). 
980 inline ios_base& 
981 unitbuf(ios_base& __base) 
982 { 
983 __base.setf(ios_base::unitbuf); 
984 return __base; 
985 } 
986 
987 /// Calls base.unsetf(ios_base::unitbuf). 
988 inline ios_base& 
989 nounitbuf(ios_base& __base) 
990 { 
991 __base.unsetf(ios_base::unitbuf); 
992 return __base; 
993 } 
994 
995 // [27.4.5.2] adjustfield manipulators 
996 /// Calls base.setf(ios_base::internal, ios_base::adjustfield). 
997 inline ios_base& 
998 internal(ios_base& __base) 
999 { 
1000 __base.setf(ios_base::internal, ios_base::adjustfield); 
1001 return __base; 
1002 } 
1003 
1004 /// Calls base.setf(ios_base::left, ios_base::adjustfield). 
1005 inline ios_base& 
1006 left(ios_base& __base) 
1007 { 
1008 __base.setf(ios_base::left, ios_base::adjustfield); 
1009 return __base; 
1010 } 
1011 
1012 /// Calls base.setf(ios_base::right, ios_base::adjustfield). 
1013 inline ios_base& 
1014 right(ios_base& __base) 
1015 { 
1016 __base.setf(ios_base::right, ios_base::adjustfield); 
1017 return __base; 
1018 } 
1019 
1020 // [27.4.5.3] basefield manipulators 
1021 /// Calls base.setf(ios_base::dec, ios_base::basefield). 
1022 inline ios_base& 
1023 dec(ios_base& __base) 
1024 { 
1025 __base.setf(ios_base::dec, ios_base::basefield); 
1026 return __base; 
1027 } 
1028 
1029 /// Calls base.setf(ios_base::hex, ios_base::basefield). 
1030 inline ios_base& 
1031 hex(ios_base& __base) 
1032 { 
1033 __base.setf(ios_base::hex, ios_base::basefield); 
1034 return __base; 
1035 } 
1036 
1037 /// Calls base.setf(ios_base::oct, ios_base::basefield). 
1038 inline ios_base& 
1039 oct(ios_base& __base) 
1040 { 
1041 __base.setf(ios_base::oct, ios_base::basefield); 
1042 return __base; 
1043 } 
1044 
1045 // [27.4.5.4] floatfield manipulators 
1046 /// Calls base.setf(ios_base::fixed, ios_base::floatfield). 
1047 inline ios_base& 
1048 fixed(ios_base& __base) 
1049 { 
1050 __base.setf(ios_base::fixed, ios_base::floatfield); 
1051 return __base; 
1052 } 
1053 
1054 /// Calls base.setf(ios_base::scientific, ios_base::floatfield). 
1055 inline ios_base& 
1056 scientific(ios_base& __base) 
1057 { 
1058 __base.setf(ios_base::scientific, ios_base::floatfield); 
1059 return __base; 
1060 } 
1061 
1062#if __cplusplus >= 201103L 
1063 // New C++11 floatfield manipulators 
1064 
1065 /// Calls 
1066 /// base.setf(ios_base::fixed|ios_base::scientific, ios_base::floatfield) 
1067 inline ios_base& 
1068 hexfloat(ios_base& __base) 
1069 { 
1070 __base.setf(ios_base::fixed | ios_base::scientific, ios_base::floatfield); 
1071 return __base; 
1072 } 
1073 
1074 /// Calls @c base.unsetf(ios_base::floatfield) 
1075 inline ios_base& 
1076 defaultfloat(ios_base& __base) 
1077 { 
1078 __base.unsetf(ios_base::floatfield); 
1079 return __base; 
1080 } 
1081#endif 
1082 
1083_GLIBCXX_END_NAMESPACE_VERSION 
1084} // namespace 
1085 
1086#endif /* _IOS_BASE_H */ 
1087