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1 : // Iostreams base classes -*- C++ -*-
2 :
3 : // Copyright (C) 1997-2013 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/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}
28 : */
29 :
30 : #ifndef _BASIC_IOS_H
31 : #define _BASIC_IOS_H 1
32 :
33 : #pragma GCC system_header
34 :
35 : #include <bits/localefwd.h>
36 : #include <bits/locale_classes.h>
37 : #include <bits/locale_facets.h>
38 : #include <bits/streambuf_iterator.h>
39 :
40 : namespace std _GLIBCXX_VISIBILITY(default)
41 : {
42 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
43 :
44 : template<typename _Facet>
45 : inline const _Facet&
46 0 : __check_facet(const _Facet* __f)
47 : {
48 0 : if (!__f)
49 0 : __throw_bad_cast();
50 0 : return *__f;
51 : }
52 :
53 : /**
54 : * @brief Template class basic_ios, virtual base class for all
55 : * stream classes.
56 : * @ingroup io
57 : *
58 : * @tparam _CharT Type of character stream.
59 : * @tparam _Traits Traits for character type, defaults to
60 : * char_traits<_CharT>.
61 : *
62 : * Most of the member functions called dispatched on stream objects
63 : * (e.g., @c std::cout.foo(bar);) are consolidated in this class.
64 : */
65 : template<typename _CharT, typename _Traits>
66 : class basic_ios : public ios_base
67 : {
68 : public:
69 : //@{
70 : /**
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.
74 : */
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;
80 : //@}
81 :
82 : //@{
83 : /**
84 : * These are non-standard types.
85 : */
86 : typedef ctype<_CharT> __ctype_type;
87 : typedef num_put<_CharT, ostreambuf_iterator<_CharT, _Traits> >
88 : __num_put_type;
89 : typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> >
90 : __num_get_type;
91 : //@}
92 :
93 : // Data members:
94 : protected:
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;
99 :
100 : // Cached use_facet<ctype>, which is based on the current locale info.
101 : const __ctype_type* _M_ctype;
102 : // For ostream.
103 : const __num_put_type* _M_num_put;
104 : // For istream.
105 : const __num_get_type* _M_num_get;
106 :
107 : public:
108 : //@{
109 : /**
110 : * @brief The quick-and-easy status check.
111 : *
112 : * This allows you to write constructs such as
113 : * <code>if (!a_stream) ...</code> and <code>while (a_stream) ...</code>
114 : */
115 : operator void*() const
116 : { return this->fail() ? 0 : const_cast<basic_ios*>(this); }
117 :
118 : bool
119 : operator!() const
120 : { return this->fail(); }
121 : //@}
122 :
123 : /**
124 : * @brief Returns the error state of the stream buffer.
125 : * @return A bit pattern (well, isn't everything?)
126 : *
127 : * See std::ios_base::iostate for the possible bit values. Most
128 : * users will call one of the interpreting wrappers, e.g., good().
129 : */
130 : iostate
131 : rdstate() const
132 : { return _M_streambuf_state; }
133 :
134 : /**
135 : * @brief [Re]sets the error state.
136 : * @param __state The new state flag(s) to set.
137 : *
138 : * See std::ios_base::iostate for the possible bit values. Most
139 : * users will not need to pass an argument.
140 : */
141 : void
142 : clear(iostate __state = goodbit);
143 :
144 : /**
145 : * @brief Sets additional flags in the error state.
146 : * @param __state The additional state flag(s) to set.
147 : *
148 : * See std::ios_base::iostate for the possible bit values.
149 : */
150 : void
151 : setstate(iostate __state)
152 : { this->clear(this->rdstate() | __state); }
153 :
154 : // Flip the internal state on for the proper state bits, then re
155 : // throws the propagated exception if bit also set in
156 : // exceptions().
157 : void
158 : _M_setstate(iostate __state)
159 : {
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;
165 : }
166 :
167 : /**
168 : * @brief Fast error checking.
169 : * @return True if no error flags are set.
170 : *
171 : * A wrapper around rdstate.
172 : */
173 : bool
174 0 : good() const
175 0 : { return this->rdstate() == 0; }
176 :
177 : /**
178 : * @brief Fast error checking.
179 : * @return True if the eofbit is set.
180 : *
181 : * Note that other iostate flags may also be set.
182 : */
183 : bool
184 0 : eof() const
185 0 : { return (this->rdstate() & eofbit) != 0; }
186 :
187 : /**
188 : * @brief Fast error checking.
189 : * @return True if either the badbit or the failbit is set.
190 : *
191 : * Checking the badbit in fail() is historical practice.
192 : * Note that other iostate flags may also be set.
193 : */
194 : bool
195 0 : fail() const
196 0 : { return (this->rdstate() & (badbit | failbit)) != 0; }
197 :
198 : /**
199 : * @brief Fast error checking.
200 : * @return True if the badbit is set.
201 : *
202 : * Note that other iostate flags may also be set.
203 : */
204 : bool
205 : bad() const
206 : { return (this->rdstate() & badbit) != 0; }
207 :
208 : /**
209 : * @brief Throwing exceptions on errors.
210 : * @return The current exceptions mask.
211 : *
212 : * This changes nothing in the stream. See the one-argument version
213 : * of exceptions(iostate) for the meaning of the return value.
214 : */
215 : iostate
216 : exceptions() const
217 : { return _M_exception; }
218 :
219 : /**
220 : * @brief Throwing exceptions on errors.
221 : * @param __except The new exceptions mask.
222 : *
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.
227 : *
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:
231 : * @code
232 : * #include <iostream>
233 : * #include <fstream>
234 : * #include <exception>
235 : *
236 : * int main()
237 : * {
238 : * std::set_terminate (__gnu_cxx::__verbose_terminate_handler);
239 : *
240 : * std::ifstream f ("/etc/motd");
241 : *
242 : * std::cerr << "Setting badbit\n";
243 : * f.setstate (std::ios_base::badbit);
244 : *
245 : * std::cerr << "Setting exception mask\n";
246 : * f.exceptions (std::ios_base::badbit);
247 : * }
248 : * @endcode
249 : */
250 : void
251 : exceptions(iostate __except)
252 : {
253 : _M_exception = __except;
254 : this->clear(_M_streambuf_state);
255 : }
256 :
257 : // Constructor/destructor:
258 : /**
259 : * @brief Constructor performs initialization.
260 : *
261 : * The parameter is passed by derived streams.
262 : */
263 : explicit
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); }
268 :
269 : /**
270 : * @brief Empty.
271 : *
272 : * The destructor does nothing. More specifically, it does not
273 : * destroy the streambuf held by rdbuf().
274 : */
275 : virtual
276 : ~basic_ios() { }
277 :
278 : // Members:
279 : /**
280 : * @brief Fetches the current @e tied stream.
281 : * @return A pointer to the tied stream, or NULL if the stream is
282 : * not tied.
283 : *
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.
287 : */
288 : basic_ostream<_CharT, _Traits>*
289 : tie() const
290 : { return _M_tie; }
291 :
292 : /**
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
296 : * was not tied.
297 : *
298 : * This sets up a new tie; see tie() for more.
299 : */
300 : basic_ostream<_CharT, _Traits>*
301 : tie(basic_ostream<_CharT, _Traits>* __tiestr)
302 : {
303 : basic_ostream<_CharT, _Traits>* __old = _M_tie;
304 : _M_tie = __tiestr;
305 : return __old;
306 : }
307 :
308 : /**
309 : * @brief Accessing the underlying buffer.
310 : * @return The current stream buffer.
311 : *
312 : * This does not change the state of the stream.
313 : */
314 : basic_streambuf<_CharT, _Traits>*
315 : rdbuf() const
316 : { return _M_streambuf; }
317 :
318 : /**
319 : * @brief Changing the underlying buffer.
320 : * @param __sb The new stream buffer.
321 : * @return The previous stream buffer.
322 : *
323 : * Associates a new buffer with the current stream, and clears the
324 : * error state.
325 : *
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:
332 : *
333 : * @code
334 : * std::fstream foo; // or some other derived type
335 : * std::streambuf* p = .....;
336 : *
337 : * foo.ios::rdbuf(p); // ios == basic_ios<char>
338 : * @endcode
339 : */
340 : basic_streambuf<_CharT, _Traits>*
341 : rdbuf(basic_streambuf<_CharT, _Traits>* __sb);
342 :
343 : /**
344 : * @brief Copies fields of __rhs into this.
345 : * @param __rhs The source values for the copies.
346 : * @return Reference to this object.
347 : *
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().
353 : */
354 : basic_ios&
355 : copyfmt(const basic_ios& __rhs);
356 :
357 : /**
358 : * @brief Retrieves the @a empty character.
359 : * @return The current fill character.
360 : *
361 : * It defaults to a space (' ') in the current locale.
362 : */
363 : char_type
364 : fill() const
365 : {
366 : if (!_M_fill_init)
367 : {
368 : _M_fill = this->widen(' ');
369 : _M_fill_init = true;
370 : }
371 : return _M_fill;
372 : }
373 :
374 : /**
375 : * @brief Sets a new @a empty character.
376 : * @param __ch The new character.
377 : * @return The previous fill character.
378 : *
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.
382 : */
383 : char_type
384 : fill(char_type __ch)
385 : {
386 0 : char_type __old = this->fill();
387 0 : _M_fill = __ch;
388 : return __old;
389 : }
390 :
391 : // Locales:
392 : /**
393 : * @brief Moves to a new locale.
394 : * @param __loc The new locale.
395 : * @return The previous locale.
396 : *
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).
399 : *
400 : * Additional l10n notes are at
401 : * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
402 : */
403 : locale
404 : imbue(const locale& __loc);
405 :
406 : /**
407 : * @brief Squeezes characters.
408 : * @param __c The character to narrow.
409 : * @param __dfault The character to narrow.
410 : * @return The narrowed character.
411 : *
412 : * Maps a character of @c char_type to a character of @c char,
413 : * if possible.
414 : *
415 : * Returns the result of
416 : * @code
417 : * std::use_facet<ctype<char_type> >(getloc()).narrow(c,dfault)
418 : * @endcode
419 : *
420 : * Additional l10n notes are at
421 : * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
422 : */
423 : char
424 : narrow(char_type __c, char __dfault) const
425 : { return __check_facet(_M_ctype).narrow(__c, __dfault); }
426 :
427 : /**
428 : * @brief Widens characters.
429 : * @param __c The character to widen.
430 : * @return The widened character.
431 : *
432 : * Maps a character of @c char to a character of @c char_type.
433 : *
434 : * Returns the result of
435 : * @code
436 : * std::use_facet<ctype<char_type> >(getloc()).widen(c)
437 : * @endcode
438 : *
439 : * Additional l10n notes are at
440 : * http://gcc.gnu.org/onlinedocs/libstdc++/manual/localization.html
441 : */
442 : char_type
443 : widen(char __c) const
444 : { return __check_facet(_M_ctype).widen(__c); }
445 :
446 : protected:
447 : // 27.4.5.1 basic_ios constructors
448 : /**
449 : * @brief Empty.
450 : *
451 : * The default constructor does nothing and is not normally
452 : * accessible to users.
453 : */
454 : basic_ios()
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)
457 : { }
458 :
459 : /**
460 : * @brief All setup is performed here.
461 : *
462 : * This is called from the public constructor. It is not virtual and
463 : * cannot be redefined.
464 : */
465 : void
466 : init(basic_streambuf<_CharT, _Traits>* __sb);
467 :
468 : void
469 : _M_cache_locale(const locale& __loc);
470 : };
471 :
472 : _GLIBCXX_END_NAMESPACE_VERSION
473 : } // namespace
474 :
475 : #include <bits/basic_ios.tcc>
476 :
477 : #endif /* _BASIC_IOS_H */
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