1 // Iostreams base classes -*- C++ -*-
3 // Copyright (C) 1997-2018 Free Software Foundation, Inc.
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)
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.
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.
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/>.
25 /** @file bits/basic_ios.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{ios}
31 #define _BASIC_IOS_H 1
33 #pragma GCC system_header
35 #include <bits/localefwd.h>
36 #include <bits/locale_classes.h>
37 #include <bits/locale_facets.h>
38 #include <bits/streambuf_iterator.h>
39 #include <bits/move.h>
41 namespace std
_GLIBCXX_VISIBILITY(default)
43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
45 template<typename _Facet
>
47 __check_facet(const _Facet
* __f
)
55 * @brief Template class basic_ios, virtual base class for all
59 * @tparam _CharT Type of character stream.
60 * @tparam _Traits Traits for character type, defaults to
61 * char_traits<_CharT>.
63 * Most of the member functions called dispatched on stream objects
64 * (e.g., @c std::cout.foo(bar);) are consolidated in this class.
66 template<typename _CharT
, typename _Traits
>
67 class basic_ios
: public ios_base
72 * These are standard types. They permit a standardized way of
73 * referring to names of (or names dependent on) the template
74 * parameters, which are specific to the implementation.
76 typedef _CharT char_type
;
77 typedef typename
_Traits::int_type int_type
;
78 typedef typename
_Traits::pos_type pos_type
;
79 typedef typename
_Traits::off_type off_type
;
80 typedef _Traits traits_type
;
85 * These are non-standard types.
87 typedef ctype
<_CharT
> __ctype_type
;
88 typedef num_put
<_CharT
, ostreambuf_iterator
<_CharT
, _Traits
> >
90 typedef num_get
<_CharT
, istreambuf_iterator
<_CharT
, _Traits
> >
96 basic_ostream
<_CharT
, _Traits
>* _M_tie
;
97 mutable char_type _M_fill
;
98 mutable bool _M_fill_init
;
99 basic_streambuf
<_CharT
, _Traits
>* _M_streambuf
;
101 // Cached use_facet<ctype>, which is based on the current locale info.
102 const __ctype_type
* _M_ctype
;
104 const __num_put_type
* _M_num_put
;
106 const __num_get_type
* _M_num_get
;
111 * @brief The quick-and-easy status check.
113 * This allows you to write constructs such as
114 * <code>if (!a_stream) ...</code> and <code>while (a_stream) ...</code>
116 #if __cplusplus >= 201103L
117 explicit operator bool() const
118 { return !this->fail(); }
120 operator void*() const
121 { return this->fail() ? 0 : const_cast<basic_ios
*>(this); }
126 { return this->fail(); }
130 * @brief Returns the error state of the stream buffer.
131 * @return A bit pattern (well, isn't everything?)
133 * See std::ios_base::iostate for the possible bit values. Most
134 * users will call one of the interpreting wrappers, e.g., good().
138 { return _M_streambuf_state
; }
141 * @brief [Re]sets the error state.
142 * @param __state The new state flag(s) to set.
144 * See std::ios_base::iostate for the possible bit values. Most
145 * users will not need to pass an argument.
148 clear(iostate __state
= goodbit
);
151 * @brief Sets additional flags in the error state.
152 * @param __state The additional state flag(s) to set.
154 * See std::ios_base::iostate for the possible bit values.
157 setstate(iostate __state
)
158 { this->clear(this->rdstate() | __state
); }
160 // Flip the internal state on for the proper state bits, then
161 // rethrows the propagated exception if bit also set in
164 _M_setstate(iostate __state
)
166 // 27.6.1.2.1 Common requirements.
167 // Turn this on without causing an ios::failure to be thrown.
168 _M_streambuf_state
|= __state
;
169 if (this->exceptions() & __state
)
170 __throw_exception_again
;
174 * @brief Fast error checking.
175 * @return True if no error flags are set.
177 * A wrapper around rdstate.
181 { return this->rdstate() == 0; }
184 * @brief Fast error checking.
185 * @return True if the eofbit is set.
187 * Note that other iostate flags may also be set.
191 { return (this->rdstate() & eofbit
) != 0; }
194 * @brief Fast error checking.
195 * @return True if either the badbit or the failbit is set.
197 * Checking the badbit in fail() is historical practice.
198 * Note that other iostate flags may also be set.
202 { return (this->rdstate() & (badbit
| failbit
)) != 0; }
205 * @brief Fast error checking.
206 * @return True if the badbit is set.
208 * Note that other iostate flags may also be set.
212 { return (this->rdstate() & badbit
) != 0; }
215 * @brief Throwing exceptions on errors.
216 * @return The current exceptions mask.
218 * This changes nothing in the stream. See the one-argument version
219 * of exceptions(iostate) for the meaning of the return value.
223 { return _M_exception
; }
226 * @brief Throwing exceptions on errors.
227 * @param __except The new exceptions mask.
229 * By default, error flags are set silently. You can set an
230 * exceptions mask for each stream; if a bit in the mask becomes set
231 * in the error flags, then an exception of type
232 * std::ios_base::failure is thrown.
234 * If the error flag is already set when the exceptions mask is
235 * added, the exception is immediately thrown. Try running the
236 * following under GCC 3.1 or later:
238 * #include <iostream>
240 * #include <exception>
244 * std::set_terminate (__gnu_cxx::__verbose_terminate_handler);
246 * std::ifstream f ("/etc/motd");
248 * std::cerr << "Setting badbit\n";
249 * f.setstate (std::ios_base::badbit);
251 * std::cerr << "Setting exception mask\n";
252 * f.exceptions (std::ios_base::badbit);
257 exceptions(iostate __except
)
259 _M_exception
= __except
;
260 this->clear(_M_streambuf_state
);
263 // Constructor/destructor:
265 * @brief Constructor performs initialization.
267 * The parameter is passed by derived streams.
270 basic_ios(basic_streambuf
<_CharT
, _Traits
>* __sb
)
271 : ios_base(), _M_tie(0), _M_fill(), _M_fill_init(false), _M_streambuf(0),
272 _M_ctype(0), _M_num_put(0), _M_num_get(0)
273 { this->init(__sb
); }
278 * The destructor does nothing. More specifically, it does not
279 * destroy the streambuf held by rdbuf().
286 * @brief Fetches the current @e tied stream.
287 * @return A pointer to the tied stream, or NULL if the stream is
290 * A stream may be @e tied (or synchronized) to a second output
291 * stream. When this stream performs any I/O, the tied stream is
292 * first flushed. For example, @c std::cin is tied to @c std::cout.
294 basic_ostream
<_CharT
, _Traits
>*
299 * @brief Ties this stream to an output stream.
300 * @param __tiestr The output stream.
301 * @return The previously tied output stream, or NULL if the stream
304 * This sets up a new tie; see tie() for more.
306 basic_ostream
<_CharT
, _Traits
>*
307 tie(basic_ostream
<_CharT
, _Traits
>* __tiestr
)
309 basic_ostream
<_CharT
, _Traits
>* __old
= _M_tie
;
315 * @brief Accessing the underlying buffer.
316 * @return The current stream buffer.
318 * This does not change the state of the stream.
320 basic_streambuf
<_CharT
, _Traits
>*
322 { return _M_streambuf
; }
325 * @brief Changing the underlying buffer.
326 * @param __sb The new stream buffer.
327 * @return The previous stream buffer.
329 * Associates a new buffer with the current stream, and clears the
332 * Due to historical accidents which the LWG refuses to correct, the
333 * I/O library suffers from a design error: this function is hidden
334 * in derived classes by overrides of the zero-argument @c rdbuf(),
335 * which is non-virtual for hysterical raisins. As a result, you
336 * must use explicit qualifications to access this function via any
337 * derived class. For example:
340 * std::fstream foo; // or some other derived type
341 * std::streambuf* p = .....;
343 * foo.ios::rdbuf(p); // ios == basic_ios<char>
346 basic_streambuf
<_CharT
, _Traits
>*
347 rdbuf(basic_streambuf
<_CharT
, _Traits
>* __sb
);
350 * @brief Copies fields of __rhs into this.
351 * @param __rhs The source values for the copies.
352 * @return Reference to this object.
354 * All fields of __rhs are copied into this object except that rdbuf()
355 * and rdstate() remain unchanged. All values in the pword and iword
356 * arrays are copied. Before copying, each callback is invoked with
357 * erase_event. After copying, each (new) callback is invoked with
358 * copyfmt_event. The final step is to copy exceptions().
361 copyfmt(const basic_ios
& __rhs
);
364 * @brief Retrieves the @a empty character.
365 * @return The current fill character.
367 * It defaults to a space (' ') in the current locale.
374 _M_fill
= this->widen(' ');
381 * @brief Sets a new @a empty character.
382 * @param __ch The new character.
383 * @return The previous fill character.
385 * The fill character is used to fill out space when P+ characters
386 * have been requested (e.g., via setw), Q characters are actually
387 * used, and Q<P. It defaults to a space (' ') in the current locale.
392 char_type __old
= this->fill();
399 * @brief Moves to a new locale.
400 * @param __loc The new locale.
401 * @return The previous locale.
403 * Calls @c ios_base::imbue(loc), and if a stream buffer is associated
404 * with this stream, calls that buffer's @c pubimbue(loc).
406 * Additional l10n notes are at
407 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
410 imbue(const locale
& __loc
);
413 * @brief Squeezes characters.
414 * @param __c The character to narrow.
415 * @param __dfault The character to narrow.
416 * @return The narrowed character.
418 * Maps a character of @c char_type to a character of @c char,
421 * Returns the result of
423 * std::use_facet<ctype<char_type> >(getloc()).narrow(c,dfault)
426 * Additional l10n notes are at
427 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
430 narrow(char_type __c
, char __dfault
) const
431 { return __check_facet(_M_ctype
).narrow(__c
, __dfault
); }
434 * @brief Widens characters.
435 * @param __c The character to widen.
436 * @return The widened character.
438 * Maps a character of @c char to a character of @c char_type.
440 * Returns the result of
442 * std::use_facet<ctype<char_type> >(getloc()).widen(c)
445 * Additional l10n notes are at
446 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
449 widen(char __c
) const
450 { return __check_facet(_M_ctype
).widen(__c
); }
453 // 27.4.5.1 basic_ios constructors
457 * The default constructor does nothing and is not normally
458 * accessible to users.
461 : ios_base(), _M_tie(0), _M_fill(char_type()), _M_fill_init(false),
462 _M_streambuf(0), _M_ctype(0), _M_num_put(0), _M_num_get(0)
466 * @brief All setup is performed here.
468 * This is called from the public constructor. It is not virtual and
469 * cannot be redefined.
472 init(basic_streambuf
<_CharT
, _Traits
>* __sb
);
474 #if __cplusplus >= 201103L
475 basic_ios(const basic_ios
&) = delete;
476 basic_ios
& operator=(const basic_ios
&) = delete;
479 move(basic_ios
& __rhs
)
481 ios_base::_M_move(__rhs
);
482 _M_cache_locale(_M_ios_locale
);
483 this->tie(__rhs
.tie(nullptr));
484 _M_fill
= __rhs
._M_fill
;
485 _M_fill_init
= __rhs
._M_fill_init
;
486 _M_streambuf
= nullptr;
490 move(basic_ios
&& __rhs
)
491 { this->move(__rhs
); }
494 swap(basic_ios
& __rhs
) noexcept
496 ios_base::_M_swap(__rhs
);
497 _M_cache_locale(_M_ios_locale
);
498 __rhs
._M_cache_locale(__rhs
._M_ios_locale
);
499 std::swap(_M_tie
, __rhs
._M_tie
);
500 std::swap(_M_fill
, __rhs
._M_fill
);
501 std::swap(_M_fill_init
, __rhs
._M_fill_init
);
505 set_rdbuf(basic_streambuf
<_CharT
, _Traits
>* __sb
)
506 { _M_streambuf
= __sb
; }
510 _M_cache_locale(const locale
& __loc
);
513 _GLIBCXX_END_NAMESPACE_VERSION
516 #include <bits/basic_ios.tcc>
518 #endif /* _BASIC_IOS_H */