1 // Iostreams base classes -*- C++ -*-
3 // Copyright (C) 1997-2014 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.
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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>
40 namespace std
_GLIBCXX_VISIBILITY(default)
42 _GLIBCXX_BEGIN_NAMESPACE_VERSION
44 template<typename _Facet
>
46 __check_facet(const _Facet
* __f
)
54 * @brief Template class basic_ios, virtual base class for all
58 * @tparam _CharT Type of character stream.
59 * @tparam _Traits Traits for character type, defaults to
60 * char_traits<_CharT>.
62 * Most of the member functions called dispatched on stream objects
63 * (e.g., @c std::cout.foo(bar);) are consolidated in this class.
65 template<typename _CharT
, typename _Traits
>
66 class basic_ios
: public ios_base
71 * These are standard types. They permit a standardized way of
72 * referring to names of (or names dependent on) the template
73 * parameters, which are specific to the implementation.
75 typedef _CharT char_type
;
76 typedef typename
_Traits::int_type int_type
;
77 typedef typename
_Traits::pos_type pos_type
;
78 typedef typename
_Traits::off_type off_type
;
79 typedef _Traits traits_type
;
84 * These are non-standard types.
86 typedef ctype
<_CharT
> __ctype_type
;
87 typedef num_put
<_CharT
, ostreambuf_iterator
<_CharT
, _Traits
> >
89 typedef num_get
<_CharT
, istreambuf_iterator
<_CharT
, _Traits
> >
95 basic_ostream
<_CharT
, _Traits
>* _M_tie
;
96 mutable char_type _M_fill
;
97 mutable bool _M_fill_init
;
98 basic_streambuf
<_CharT
, _Traits
>* _M_streambuf
;
100 // Cached use_facet<ctype>, which is based on the current locale info.
101 const __ctype_type
* _M_ctype
;
103 const __num_put_type
* _M_num_put
;
105 const __num_get_type
* _M_num_get
;
110 * @brief The quick-and-easy status check.
112 * This allows you to write constructs such as
113 * <code>if (!a_stream) ...</code> and <code>while (a_stream) ...</code>
115 operator void*() const
116 { return this->fail() ? 0 : const_cast<basic_ios
*>(this); }
120 { return this->fail(); }
124 * @brief Returns the error state of the stream buffer.
125 * @return A bit pattern (well, isn't everything?)
127 * See std::ios_base::iostate for the possible bit values. Most
128 * users will call one of the interpreting wrappers, e.g., good().
132 { return _M_streambuf_state
; }
135 * @brief [Re]sets the error state.
136 * @param __state The new state flag(s) to set.
138 * See std::ios_base::iostate for the possible bit values. Most
139 * users will not need to pass an argument.
142 clear(iostate __state
= goodbit
);
145 * @brief Sets additional flags in the error state.
146 * @param __state The additional state flag(s) to set.
148 * See std::ios_base::iostate for the possible bit values.
151 setstate(iostate __state
)
152 { this->clear(this->rdstate() | __state
); }
154 // Flip the internal state on for the proper state bits, then re
155 // throws the propagated exception if bit also set in
158 _M_setstate(iostate __state
)
160 // 27.6.1.2.1 Common requirements.
161 // Turn this on without causing an ios::failure to be thrown.
162 _M_streambuf_state
|= __state
;
163 if (this->exceptions() & __state
)
164 __throw_exception_again
;
168 * @brief Fast error checking.
169 * @return True if no error flags are set.
171 * A wrapper around rdstate.
175 { return this->rdstate() == 0; }
178 * @brief Fast error checking.
179 * @return True if the eofbit is set.
181 * Note that other iostate flags may also be set.
185 { return (this->rdstate() & eofbit
) != 0; }
188 * @brief Fast error checking.
189 * @return True if either the badbit or the failbit is set.
191 * Checking the badbit in fail() is historical practice.
192 * Note that other iostate flags may also be set.
196 { return (this->rdstate() & (badbit
| failbit
)) != 0; }
199 * @brief Fast error checking.
200 * @return True if the badbit is set.
202 * Note that other iostate flags may also be set.
206 { return (this->rdstate() & badbit
) != 0; }
209 * @brief Throwing exceptions on errors.
210 * @return The current exceptions mask.
212 * This changes nothing in the stream. See the one-argument version
213 * of exceptions(iostate) for the meaning of the return value.
217 { return _M_exception
; }
220 * @brief Throwing exceptions on errors.
221 * @param __except The new exceptions mask.
223 * By default, error flags are set silently. You can set an
224 * exceptions mask for each stream; if a bit in the mask becomes set
225 * in the error flags, then an exception of type
226 * std::ios_base::failure is thrown.
228 * If the error flag is already set when the exceptions mask is
229 * added, the exception is immediately thrown. Try running the
230 * following under GCC 3.1 or later:
232 * #include <iostream>
234 * #include <exception>
238 * std::set_terminate (__gnu_cxx::__verbose_terminate_handler);
240 * std::ifstream f ("/etc/motd");
242 * std::cerr << "Setting badbit\n";
243 * f.setstate (std::ios_base::badbit);
245 * std::cerr << "Setting exception mask\n";
246 * f.exceptions (std::ios_base::badbit);
251 exceptions(iostate __except
)
253 _M_exception
= __except
;
254 this->clear(_M_streambuf_state
);
257 // Constructor/destructor:
259 * @brief Constructor performs initialization.
261 * The parameter is passed by derived streams.
264 basic_ios(basic_streambuf
<_CharT
, _Traits
>* __sb
)
265 : ios_base(), _M_tie(0), _M_fill(), _M_fill_init(false), _M_streambuf(0),
266 _M_ctype(0), _M_num_put(0), _M_num_get(0)
267 { this->init(__sb
); }
272 * The destructor does nothing. More specifically, it does not
273 * destroy the streambuf held by rdbuf().
280 * @brief Fetches the current @e tied stream.
281 * @return A pointer to the tied stream, or NULL if the stream is
284 * A stream may be @e tied (or synchronized) to a second output
285 * stream. When this stream performs any I/O, the tied stream is
286 * first flushed. For example, @c std::cin is tied to @c std::cout.
288 basic_ostream
<_CharT
, _Traits
>*
293 * @brief Ties this stream to an output stream.
294 * @param __tiestr The output stream.
295 * @return The previously tied output stream, or NULL if the stream
298 * This sets up a new tie; see tie() for more.
300 basic_ostream
<_CharT
, _Traits
>*
301 tie(basic_ostream
<_CharT
, _Traits
>* __tiestr
)
303 basic_ostream
<_CharT
, _Traits
>* __old
= _M_tie
;
309 * @brief Accessing the underlying buffer.
310 * @return The current stream buffer.
312 * This does not change the state of the stream.
314 basic_streambuf
<_CharT
, _Traits
>*
316 { return _M_streambuf
; }
319 * @brief Changing the underlying buffer.
320 * @param __sb The new stream buffer.
321 * @return The previous stream buffer.
323 * Associates a new buffer with the current stream, and clears the
326 * Due to historical accidents which the LWG refuses to correct, the
327 * I/O library suffers from a design error: this function is hidden
328 * in derived classes by overrides of the zero-argument @c rdbuf(),
329 * which is non-virtual for hysterical raisins. As a result, you
330 * must use explicit qualifications to access this function via any
331 * derived class. For example:
334 * std::fstream foo; // or some other derived type
335 * std::streambuf* p = .....;
337 * foo.ios::rdbuf(p); // ios == basic_ios<char>
340 basic_streambuf
<_CharT
, _Traits
>*
341 rdbuf(basic_streambuf
<_CharT
, _Traits
>* __sb
);
344 * @brief Copies fields of __rhs into this.
345 * @param __rhs The source values for the copies.
346 * @return Reference to this object.
348 * All fields of __rhs are copied into this object except that rdbuf()
349 * and rdstate() remain unchanged. All values in the pword and iword
350 * arrays are copied. Before copying, each callback is invoked with
351 * erase_event. After copying, each (new) callback is invoked with
352 * copyfmt_event. The final step is to copy exceptions().
355 copyfmt(const basic_ios
& __rhs
);
358 * @brief Retrieves the @a empty character.
359 * @return The current fill character.
361 * It defaults to a space (' ') in the current locale.
368 _M_fill
= this->widen(' ');
375 * @brief Sets a new @a empty character.
376 * @param __ch The new character.
377 * @return The previous fill character.
379 * The fill character is used to fill out space when P+ characters
380 * have been requested (e.g., via setw), Q characters are actually
381 * used, and Q<P. It defaults to a space (' ') in the current locale.
386 char_type __old
= this->fill();
393 * @brief Moves to a new locale.
394 * @param __loc The new locale.
395 * @return The previous locale.
397 * Calls @c ios_base::imbue(loc), and if a stream buffer is associated
398 * with this stream, calls that buffer's @c pubimbue(loc).
400 * Additional l10n notes are at
401 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
404 imbue(const locale
& __loc
);
407 * @brief Squeezes characters.
408 * @param __c The character to narrow.
409 * @param __dfault The character to narrow.
410 * @return The narrowed character.
412 * Maps a character of @c char_type to a character of @c char,
415 * Returns the result of
417 * std::use_facet<ctype<char_type> >(getloc()).narrow(c,dfault)
420 * Additional l10n notes are at
421 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
424 narrow(char_type __c
, char __dfault
) const
425 { return __check_facet(_M_ctype
).narrow(__c
, __dfault
); }
428 * @brief Widens characters.
429 * @param __c The character to widen.
430 * @return The widened character.
432 * Maps a character of @c char to a character of @c char_type.
434 * Returns the result of
436 * std::use_facet<ctype<char_type> >(getloc()).widen(c)
439 * Additional l10n notes are at
440 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
443 widen(char __c
) const
444 { return __check_facet(_M_ctype
).widen(__c
); }
447 // 27.4.5.1 basic_ios constructors
451 * The default constructor does nothing and is not normally
452 * accessible to users.
455 : ios_base(), _M_tie(0), _M_fill(char_type()), _M_fill_init(false),
456 _M_streambuf(0), _M_ctype(0), _M_num_put(0), _M_num_get(0)
460 * @brief All setup is performed here.
462 * This is called from the public constructor. It is not virtual and
463 * cannot be redefined.
466 init(basic_streambuf
<_CharT
, _Traits
>* __sb
);
469 _M_cache_locale(const locale
& __loc
);
472 _GLIBCXX_END_NAMESPACE_VERSION
475 #include <bits/basic_ios.tcc>
477 #endif /* _BASIC_IOS_H */