1 // Iostreams base classes -*- C++ -*-
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4 // 2006, 2007, 2008, 2009, 2010, 2011
5 // Free Software Foundation, Inc.
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27 /** @file bits/basic_ios.h
28 * This is an internal header file, included by other library headers.
29 * Do not attempt to use it directly. @headername{ios}
33 #define _BASIC_IOS_H 1
35 #pragma GCC system_header
37 #include <bits/localefwd.h>
38 #include <bits/locale_classes.h>
39 #include <bits/locale_facets.h>
40 #include <bits/streambuf_iterator.h>
42 namespace std _GLIBCXX_VISIBILITY(default)
44 _GLIBCXX_BEGIN_NAMESPACE_VERSION
46 template<typename _Facet>
48 __check_facet(const _Facet* __f)
55 // 27.4.5 Template class basic_ios
57 * @brief Virtual base class for all stream classes.
60 * Most of the member functions called dispatched on stream objects
61 * (e.g., @c std::cout.foo(bar);) are consolidated in this class.
63 template<typename _CharT, typename _Traits>
64 class basic_ios : public ios_base
69 * These are standard types. They permit a standardized way of
70 * referring to names of (or names dependant on) the template
71 * parameters, which are specific to the implementation.
73 typedef _CharT char_type;
74 typedef typename _Traits::int_type int_type;
75 typedef typename _Traits::pos_type pos_type;
76 typedef typename _Traits::off_type off_type;
77 typedef _Traits traits_type;
82 * These are non-standard types.
84 typedef ctype<_CharT> __ctype_type;
85 typedef num_put<_CharT, ostreambuf_iterator<_CharT, _Traits> >
87 typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> >
93 basic_ostream<_CharT, _Traits>* _M_tie;
94 mutable char_type _M_fill;
95 mutable bool _M_fill_init;
96 basic_streambuf<_CharT, _Traits>* _M_streambuf;
98 // Cached use_facet<ctype>, which is based on the current locale info.
99 const __ctype_type* _M_ctype;
101 const __num_put_type* _M_num_put;
103 const __num_get_type* _M_num_get;
108 * @brief The quick-and-easy status check.
110 * This allows you to write constructs such as
111 * <code>if (!a_stream) ...</code> and <code>while (a_stream) ...</code>
113 operator void*() const
114 { return this->fail() ? 0 : const_cast<basic_ios*>(this); }
118 { return this->fail(); }
122 * @brief Returns the error state of the stream buffer.
123 * @return A bit pattern (well, isn't everything?)
125 * See std::ios_base::iostate for the possible bit values. Most
126 * users will call one of the interpreting wrappers, e.g., good().
130 { return _M_streambuf_state; }
133 * @brief [Re]sets the error state.
134 * @param state The new state flag(s) to set.
136 * See std::ios_base::iostate for the possible bit values. Most
137 * users will not need to pass an argument.
140 clear(iostate __state = goodbit);
143 * @brief Sets additional flags in the error state.
144 * @param state The additional state flag(s) to set.
146 * See std::ios_base::iostate for the possible bit values.
149 setstate(iostate __state)
150 { this->clear(this->rdstate() | __state); }
152 // Flip the internal state on for the proper state bits, then re
153 // throws the propagated exception if bit also set in
156 _M_setstate(iostate __state)
158 // 27.6.1.2.1 Common requirements.
159 // Turn this on without causing an ios::failure to be thrown.
160 _M_streambuf_state |= __state;
161 if (this->exceptions() & __state)
162 __throw_exception_again;
166 * @brief Fast error checking.
167 * @return True if no error flags are set.
169 * A wrapper around rdstate.
173 { return this->rdstate() == 0; }
176 * @brief Fast error checking.
177 * @return True if the eofbit is set.
179 * Note that other iostate flags may also be set.
183 { return (this->rdstate() & eofbit) != 0; }
186 * @brief Fast error checking.
187 * @return True if either the badbit or the failbit is set.
189 * Checking the badbit in fail() is historical practice.
190 * Note that other iostate flags may also be set.
194 { return (this->rdstate() & (badbit | failbit)) != 0; }
197 * @brief Fast error checking.
198 * @return True if the badbit is set.
200 * Note that other iostate flags may also be set.
204 { return (this->rdstate() & badbit) != 0; }
207 * @brief Throwing exceptions on errors.
208 * @return The current exceptions mask.
210 * This changes nothing in the stream. See the one-argument version
211 * of exceptions(iostate) for the meaning of the return value.
215 { return _M_exception; }
218 * @brief Throwing exceptions on errors.
219 * @param except The new exceptions mask.
221 * By default, error flags are set silently. You can set an
222 * exceptions mask for each stream; if a bit in the mask becomes set
223 * in the error flags, then an exception of type
224 * std::ios_base::failure is thrown.
226 * If the error flag is already set when the exceptions mask is
227 * added, the exception is immediately thrown. Try running the
228 * following under GCC 3.1 or later:
230 * #include <iostream>
232 * #include <exception>
236 * std::set_terminate (__gnu_cxx::__verbose_terminate_handler);
238 * std::ifstream f ("/etc/motd");
240 * std::cerr << "Setting badbit\n";
241 * f.setstate (std::ios_base::badbit);
243 * std::cerr << "Setting exception mask\n";
244 * f.exceptions (std::ios_base::badbit);
249 exceptions(iostate __except)
251 _M_exception = __except;
252 this->clear(_M_streambuf_state);
255 // Constructor/destructor:
257 * @brief Constructor performs initialization.
259 * The parameter is passed by derived streams.
262 basic_ios(basic_streambuf<_CharT, _Traits>* __sb)
263 : ios_base(), _M_tie(0), _M_fill(), _M_fill_init(false), _M_streambuf(0),
264 _M_ctype(0), _M_num_put(0), _M_num_get(0)
265 { this->init(__sb); }
270 * The destructor does nothing. More specifically, it does not
271 * destroy the streambuf held by rdbuf().
278 * @brief Fetches the current @e tied stream.
279 * @return A pointer to the tied stream, or NULL if the stream is
282 * A stream may be @e tied (or synchronized) to a second output
283 * stream. When this stream performs any I/O, the tied stream is
284 * first flushed. For example, @c std::cin is tied to @c std::cout.
286 basic_ostream<_CharT, _Traits>*
291 * @brief Ties this stream to an output stream.
292 * @param tiestr The output stream.
293 * @return The previously tied output stream, or NULL if the stream
296 * This sets up a new tie; see tie() for more.
298 basic_ostream<_CharT, _Traits>*
299 tie(basic_ostream<_CharT, _Traits>* __tiestr)
301 basic_ostream<_CharT, _Traits>* __old = _M_tie;
307 * @brief Accessing the underlying buffer.
308 * @return The current stream buffer.
310 * This does not change the state of the stream.
312 basic_streambuf<_CharT, _Traits>*
314 { return _M_streambuf; }
317 * @brief Changing the underlying buffer.
318 * @param sb The new stream buffer.
319 * @return The previous stream buffer.
321 * Associates a new buffer with the current stream, and clears the
324 * Due to historical accidents which the LWG refuses to correct, the
325 * I/O library suffers from a design error: this function is hidden
326 * in derived classes by overrides of the zero-argument @c rdbuf(),
327 * which is non-virtual for hysterical raisins. As a result, you
328 * must use explicit qualifications to access this function via any
329 * derived class. For example:
332 * std::fstream foo; // or some other derived type
333 * std::streambuf* p = .....;
335 * foo.ios::rdbuf(p); // ios == basic_ios<char>
338 basic_streambuf<_CharT, _Traits>*
339 rdbuf(basic_streambuf<_CharT, _Traits>* __sb);
342 * @brief Copies fields of __rhs into this.
343 * @param __rhs The source values for the copies.
344 * @return Reference to this object.
346 * All fields of __rhs are copied into this object except that rdbuf()
347 * and rdstate() remain unchanged. All values in the pword and iword
348 * arrays are copied. Before copying, each callback is invoked with
349 * erase_event. After copying, each (new) callback is invoked with
350 * copyfmt_event. The final step is to copy exceptions().
353 copyfmt(const basic_ios& __rhs);
356 * @brief Retrieves the @a empty character.
357 * @return The current fill character.
359 * It defaults to a space (' ') in the current locale.
366 _M_fill = this->widen(' ');
373 * @brief Sets a new @a empty character.
374 * @param ch The new character.
375 * @return The previous fill character.
377 * The fill character is used to fill out space when P+ characters
378 * have been requested (e.g., via setw), Q characters are actually
379 * used, and Q<P. It defaults to a space (' ') in the current locale.
384 char_type __old = this->fill();
391 * @brief Moves to a new locale.
392 * @param loc The new locale.
393 * @return The previous locale.
395 * Calls @c ios_base::imbue(loc), and if a stream buffer is associated
396 * with this stream, calls that buffer's @c pubimbue(loc).
398 * Additional l10n notes are at
399 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
402 imbue(const locale& __loc);
405 * @brief Squeezes characters.
406 * @param c The character to narrow.
407 * @param dfault The character to narrow.
408 * @return The narrowed character.
410 * Maps a character of @c char_type to a character of @c char,
413 * Returns the result of
415 * std::use_facet<ctype<char_type> >(getloc()).narrow(c,dfault)
418 * Additional l10n notes are at
419 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
422 narrow(char_type __c, char __dfault) const
423 { return __check_facet(_M_ctype).narrow(__c, __dfault); }
426 * @brief Widens characters.
427 * @param c The character to widen.
428 * @return The widened character.
430 * Maps a character of @c char to a character of @c char_type.
432 * Returns the result of
434 * std::use_facet<ctype<char_type> >(getloc()).widen(c)
437 * Additional l10n notes are at
438 * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
441 widen(char __c) const
442 { return __check_facet(_M_ctype).widen(__c); }
445 // 27.4.5.1 basic_ios constructors
449 * The default constructor does nothing and is not normally
450 * accessible to users.
453 : ios_base(), _M_tie(0), _M_fill(char_type()), _M_fill_init(false),
454 _M_streambuf(0), _M_ctype(0), _M_num_put(0), _M_num_get(0)
458 * @brief All setup is performed here.
460 * This is called from the public constructor. It is not virtual and
461 * cannot be redefined.
464 init(basic_streambuf<_CharT, _Traits>* __sb);
467 _M_cache_locale(const locale& __loc);
470 _GLIBCXX_END_NAMESPACE_VERSION
473 #include <bits/basic_ios.tcc>
475 #endif /* _BASIC_IOS_H */