| blob | 3dec366fcc1655d20b16a1abea3cefa008607371 |
1 // File based streams -*- C++ -*-
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
4 // Free Software Foundation, Inc.
5 //
6 // This file is part of the GNU ISO C++ Library. This library is free
7 // software; you can redistribute it and/or modify it under the
8 // terms of the GNU General Public License as published by the
9 // Free Software Foundation; either version 2, or (at your option)
10 // any later version.
12 // This library is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
17 // You should have received a copy of the GNU General Public License along
18 // with this library; see the file COPYING. If not, write to the Free
19 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
20 // USA.
22 // As a special exception, you may use this file as part of a free software
23 // library without restriction. Specifically, if other files instantiate
24 // templates or use macros or inline functions from this file, or you compile
25 // this file and link it with other files to produce an executable, this
26 // file does not by itself cause the resulting executable to be covered by
27 // the GNU General Public License. This exception does not however
28 // invalidate any other reasons why the executable file might be covered by
29 // the GNU General Public License.
31 //
32 // ISO C++ 14882: 27.8 File-based streams
33 //
35 /** @file fstream
36 * This is a Standard C++ Library header. You should @c #include this header
37 * in your programs, rather than any of the "st[dl]_*.h" implementation files.
38 */
40 #ifndef _GLIBCXX_FSTREAM
41 #define _GLIBCXX_FSTREAM 1
43 #pragma GCC system_header
45 #include <istream>
46 #include <ostream>
47 #include <locale> // For codecvt
48 #include <cstdio> // For SEEK_SET, SEEK_CUR, SEEK_END, BUFSIZ
49 #include <bits/basic_file.h>
50 #include <bits/gthr.h>
52 namespace std
53 {
54 // [27.8.1.1] template class basic_filebuf
55 /**
56 * @brief The actual work of input and output (for files).
57 *
58 * This class associates both its input and output sequence with an
59 * external disk file, and maintains a joint file position for both
60 * sequences. Many of its sematics are described in terms of similar
61 * behavior in the Standard C Library's @c FILE streams.
62 */
63 // Requirements on traits_type, specific to this class:
64 // traits_type::pos_type must be fpos<traits_type::state_type>
65 // traits_type::off_type must be streamoff
66 // traits_type::state_type must be Assignable and DefaultConstructable,
67 // and traits_type::state_type() must be the initial state for codecvt.
68 template<typename _CharT, typename _Traits>
69 class basic_filebuf : public basic_streambuf<_CharT, _Traits>
70 {
71 public:
72 // Types:
73 typedef _CharT char_type;
74 typedef _Traits traits_type;
75 typedef typename traits_type::int_type int_type;
76 typedef typename traits_type::pos_type pos_type;
77 typedef typename traits_type::off_type off_type;
79 //@{
80 /**
81 * @if maint
82 * @doctodo
83 * @endif
84 */
85 typedef basic_streambuf<char_type, traits_type> __streambuf_type;
86 typedef basic_filebuf<char_type, traits_type> __filebuf_type;
87 typedef __basic_file<char> __file_type;
88 typedef typename traits_type::state_type __state_type;
89 typedef codecvt<char_type, char, __state_type> __codecvt_type;
90 //@}
92 friend class ios_base; // For sync_with_stdio.
94 protected:
95 // Data Members:
96 // MT lock inherited from libio or other low-level io library.
97 /**
98 * @if maint
99 * @doctodo
100 * @endif
101 */
102 __c_lock _M_lock;
104 // External buffer.
105 /**
106 * @if maint
107 * @doctodo
108 * @endif
109 */
110 __file_type _M_file;
112 /**
113 * @if maint
114 * Place to stash in || out || in | out settings for current filebuf.
115 * @endif
116 */
117 ios_base::openmode _M_mode;
119 // Beginning state type for codecvt.
120 /**
121 * @if maint
122 * @doctodo
123 * @endif
124 */
125 __state_type _M_state_beg;
127 // During output, the state that corresponds to pptr(),
128 // during input, the state that corresponds to egptr() and
129 // _M_ext_next.
130 /**
131 * @if maint
132 * @doctodo
133 * @endif
134 */
135 __state_type _M_state_cur;
137 // Not used for output. During input, the state that corresponds
138 // to eback() and _M_ext_buf.
139 /**
140 * @if maint
141 * @doctodo
142 * @endif
143 */
144 __state_type _M_state_last;
146 /**
147 * @if maint
148 * Pointer to the beginning of internal buffer.
149 * @endif
150 */
151 char_type* _M_buf;
153 /**
154 * @if maint
155 * Actual size of internal buffer. This number is equal to the size
156 * of the put area + 1 position, reserved for the overflow char of
157 * a full area.
158 * @endif
159 */
160 size_t _M_buf_size;
162 // Set iff _M_buf is allocated memory from _M_allocate_internal_buffer.
163 /**
164 * @if maint
165 * @doctodo
166 * @endif
167 */
168 bool _M_buf_allocated;
170 /**
171 * @if maint
172 * _M_reading == false && _M_writing == false for 'uncommitted' mode;
173 * _M_reading == true for 'read' mode;
174 * _M_writing == true for 'write' mode;
175 *
176 * NB: _M_reading == true && _M_writing == true is unused.
177 * @endif
178 */
179 bool _M_reading;
180 bool _M_writing;
182 //@{
183 /**
184 * @if maint
185 * Necessary bits for putback buffer management.
186 *
187 * @note pbacks of over one character are not currently supported.
188 * @endif
189 */
190 char_type _M_pback;
191 char_type* _M_pback_cur_save;
192 char_type* _M_pback_end_save;
193 bool _M_pback_init;
194 //@}
196 // Cached codecvt facet.
197 const __codecvt_type* _M_codecvt;
199 /**
200 * @if maint
201 * Buffer for external characters. Used for input when
202 * codecvt::always_noconv() == false. When valid, this corresponds
203 * to eback().
204 * @endif
205 */
206 char* _M_ext_buf;
208 /**
209 * @if maint
210 * Size of buffer held by _M_ext_buf.
211 * @endif
212 */
213 streamsize _M_ext_buf_size;
215 /**
216 * @if maint
217 * Pointers into the buffer held by _M_ext_buf that delimit a
218 * subsequence of bytes that have been read but not yet converted.
219 * When valid, _M_ext_next corresponds to egptr().
220 * @endif
221 */
222 const char* _M_ext_next;
223 char* _M_ext_end;
225 /**
226 * @if maint
227 * Initializes pback buffers, and moves normal buffers to safety.
228 * Assumptions:
229 * _M_in_cur has already been moved back
230 * @endif
231 */
232 void
233 _M_create_pback()
234 {
235 if (!_M_pback_init)
236 {
237 _M_pback_cur_save = this->gptr();
238 _M_pback_end_save = this->egptr();
239 this->setg(&_M_pback, &_M_pback, &_M_pback + 1);
240 _M_pback_init = true;
241 }
242 }
244 /**
245 * @if maint
246 * Deactivates pback buffer contents, and restores normal buffer.
247 * Assumptions:
248 * The pback buffer has only moved forward.
249 * @endif
250 */
251 void
252 _M_destroy_pback() throw()
253 {
254 if (_M_pback_init)
255 {
256 // Length _M_in_cur moved in the pback buffer.
257 _M_pback_cur_save += this->gptr() != this->eback();
258 this->setg(this->_M_buf, _M_pback_cur_save, _M_pback_end_save);
259 _M_pback_init = false;
260 }
261 }
263 public:
264 // Constructors/destructor:
265 /**
266 * @brief Does not open any files.
267 *
268 * The default constructor initializes the parent class using its
269 * own default ctor.
270 */
271 basic_filebuf();
273 /**
274 * @brief The destructor closes the file first.
275 */
276 virtual
277 ~basic_filebuf()
278 { this->close(); }
280 // Members:
281 /**
282 * @brief Returns true if the external file is open.
283 */
284 bool
285 is_open() const throw() { return _M_file.is_open(); }
287 /**
288 * @brief Opens an external file.
289 * @param s The name of the file.
290 * @param mode The open mode flags.
291 * @return @c this on success, NULL on failure
292 *
293 * If a file is already open, this function immediately fails.
294 * Otherwise it tries to open the file named @a s using the flags
295 * given in @a mode.
296 *
297 * [Table 92 gives the relation between openmode combinations and the
298 * equivalent fopen() flags, but the table has not been copied yet.]
299 */
300 __filebuf_type*
301 open(const char* __s, ios_base::openmode __mode);
303 /**
304 * @brief Closes the currently associated file.
305 * @return @c this on success, NULL on failure
306 *
307 * If no file is currently open, this function immediately fails.
308 *
309 * If a "put buffer area" exists, @c overflow(eof) is called to flush
310 * all the characters. The file is then closed.
311 *
312 * If any operations fail, this function also fails.
313 */
314 __filebuf_type*
315 close() throw();
317 protected:
318 /**
319 * @if maint
320 * @doctodo
321 * @endif
322 */
323 void
324 _M_allocate_internal_buffer();
326 /**
327 * @if maint
328 * @doctodo
329 * @endif
330 */
331 void
332 _M_destroy_internal_buffer() throw();
334 // [27.8.1.4] overridden virtual functions
335 // [documentation is inherited]
336 virtual streamsize
337 showmanyc();
339 // Stroustrup, 1998, p. 628
340 // underflow() and uflow() functions are called to get the next
341 // charater from the real input source when the buffer is empty.
342 // Buffered input uses underflow()
344 // [documentation is inherited]
345 virtual int_type
346 underflow();
348 // [documentation is inherited]
349 virtual int_type
350 pbackfail(int_type __c = _Traits::eof());
352 // Stroustrup, 1998, p 648
353 // The overflow() function is called to transfer characters to the
354 // real output destination when the buffer is full. A call to
355 // overflow(c) outputs the contents of the buffer plus the
356 // character c.
357 // 27.5.2.4.5
358 // Consume some sequence of the characters in the pending sequence.
359 /**
360 * @if maint
361 * @doctodo
362 * @endif
363 */
364 virtual int_type
365 overflow(int_type __c = _Traits::eof());
367 // Convert internal byte sequence to external, char-based
368 // sequence via codecvt.
369 /**
370 * @if maint
371 * @doctodo
372 * @endif
373 */
374 bool
375 _M_convert_to_external(char_type*, streamsize);
377 /**
378 * @brief Manipulates the buffer.
379 * @param s Pointer to a buffer area.
380 * @param n Size of @a s.
381 * @return @c this
382 *
383 * If no file has been opened, and both @a s and @a n are zero, then
384 * the stream becomes unbuffered. Otherwise, @c s is used as a
385 * buffer; see
386 * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2
387 * for more.
388 */
389 virtual __streambuf_type*
390 setbuf(char_type* __s, streamsize __n);
392 // [documentation is inherited]
393 virtual pos_type
394 seekoff(off_type __off, ios_base::seekdir __way,
395 ios_base::openmode __mode = ios_base::in | ios_base::out);
397 // [documentation is inherited]
398 virtual pos_type
399 seekpos(pos_type __pos,
400 ios_base::openmode __mode = ios_base::in | ios_base::out);
402 // Common code for seekoff and seekpos
403 /**
404 * @if maint
405 * @doctodo
406 * @endif
407 */
408 pos_type
409 _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state);
411 // [documentation is inherited]
412 virtual int
413 sync();
415 // [documentation is inherited]
416 virtual void
417 imbue(const locale& __loc);
419 // [documentation is inherited]
420 virtual streamsize
421 xsgetn(char_type* __s, streamsize __n);
423 // [documentation is inherited]
424 virtual streamsize
425 xsputn(const char_type* __s, streamsize __n);
427 // Flushes output buffer, then writes unshift sequence.
428 /**
429 * @if maint
430 * @doctodo
431 * @endif
432 */
433 bool
434 _M_terminate_output();
436 /**
437 * @if maint
438 * This function sets the pointers of the internal buffer, both get
439 * and put areas. Typically:
440 *
441 * __off == egptr() - eback() upon underflow/uflow ('read' mode);
442 * __off == 0 upon overflow ('write' mode);
443 * __off == -1 upon open, setbuf, seekoff/pos ('uncommitted' mode).
444 *
445 * NB: epptr() - pbase() == _M_buf_size - 1, since _M_buf_size
446 * reflects the actual allocated memory and the last cell is reserved
447 * for the overflow char of a full put area.
448 * @endif
449 */
450 void
451 _M_set_buffer(streamsize __off)
452 {
453 const bool __testin = this->_M_mode & ios_base::in;
454 const bool __testout = this->_M_mode & ios_base::out;
456 if (__testin && __off > 0)
457 this->setg(this->_M_buf, this->_M_buf, this->_M_buf + __off);
458 else
459 this->setg(this->_M_buf, this->_M_buf, this->_M_buf);
461 if (__testout && __off == 0 && this->_M_buf_size > 1 )
462 this->setp(this->_M_buf, this->_M_buf + this->_M_buf_size - 1);
463 else
464 this->setp(NULL, NULL);
465 }
466 };
468 // [27.8.1.5] Template class basic_ifstream
469 /**
470 * @brief Controlling input for files.
471 *
472 * This class supports reading from named files, using the inherited
473 * functions from std::basic_istream. To control the associated
474 * sequence, an instance of std::basic_filebuf is used, which this page
475 * refers to as @c sb.
476 */
477 template<typename _CharT, typename _Traits>
478 class basic_ifstream : public basic_istream<_CharT, _Traits>
479 {
480 public:
481 // Types:
482 typedef _CharT char_type;
483 typedef _Traits traits_type;
484 typedef typename traits_type::int_type int_type;
485 typedef typename traits_type::pos_type pos_type;
486 typedef typename traits_type::off_type off_type;
488 // Non-standard types:
489 typedef basic_filebuf<char_type, traits_type> __filebuf_type;
490 typedef basic_istream<char_type, traits_type> __istream_type;
492 private:
493 /**
494 * @if maint
495 * @doctodo
496 * @endif
497 */
498 __filebuf_type _M_filebuf;
500 public:
501 // Constructors/Destructors:
502 /**
503 * @brief Default constructor.
504 *
505 * Initializes @c sb using its default constructor, and passes
506 * @c &sb to the base class initializer. Does not open any files
507 * (you haven't given it a filename to open).
508 */
509 basic_ifstream() : __istream_type(), _M_filebuf()
510 { this->init(&_M_filebuf); }
512 /**
513 * @brief Create an input file stream.
514 * @param s Null terminated string specifying the filename.
515 * @param mode Open file in specified mode (see std::ios_base).
516 *
517 * @c ios_base::in is automatically included in @a mode.
518 *
519 * Tip: When using std::string to hold the filename, you must use
520 * .c_str() before passing it to this constructor.
521 */
522 explicit
523 basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
524 : __istream_type(), _M_filebuf()
525 {
526 this->init(&_M_filebuf);
527 this->open(__s, __mode);
528 }
530 /**
531 * @brief The destructor does nothing.
532 *
533 * The file is closed by the filebuf object, not the formatting
534 * stream.
535 */
536 ~basic_ifstream()
537 { }
539 // Members:
540 /**
541 * @brief Accessing the underlying buffer.
542 * @return The current basic_filebuf buffer.
543 *
544 * This hides both signatures of std::basic_ios::rdbuf().
545 */
546 __filebuf_type*
547 rdbuf() const
548 { return const_cast<__filebuf_type*>(&_M_filebuf); }
550 /**
551 * @brief Wrapper to test for an open file.
552 * @return @c rdbuf()->is_open()
553 */
554 bool
555 is_open() { return _M_filebuf.is_open(); }
557 /**
558 * @brief Opens an external file.
559 * @param s The name of the file.
560 * @param mode The open mode flags.
561 *
562 * Calls @c std::basic_filebuf::open(s,mode|in). If that function
563 * fails, @c failbit is set in the stream's error state.
564 *
565 * Tip: When using std::string to hold the filename, you must use
566 * .c_str() before passing it to this constructor.
567 */
568 void
569 open(const char* __s, ios_base::openmode __mode = ios_base::in)
570 {
571 if (!_M_filebuf.open(__s, __mode | ios_base::in))
572 this->setstate(ios_base::failbit);
573 }
575 /**
576 * @brief Close the file.
577 *
578 * Calls @c std::basic_filebuf::close(). If that function
579 * fails, @c failbit is set in the stream's error state.
580 */
581 void
582 close()
583 {
584 if (!_M_filebuf.close())
585 this->setstate(ios_base::failbit);
586 }
587 };
590 // [27.8.1.8] Template class basic_ofstream
591 /**
592 * @brief Controlling output for files.
593 *
594 * This class supports reading from named files, using the inherited
595 * functions from std::basic_ostream. To control the associated
596 * sequence, an instance of std::basic_filebuf is used, which this page
597 * refers to as @c sb.
598 */
599 template<typename _CharT, typename _Traits>
600 class basic_ofstream : public basic_ostream<_CharT,_Traits>
601 {
602 public:
603 // Types:
604 typedef _CharT char_type;
605 typedef _Traits traits_type;
606 typedef typename traits_type::int_type int_type;
607 typedef typename traits_type::pos_type pos_type;
608 typedef typename traits_type::off_type off_type;
610 // Non-standard types:
611 typedef basic_filebuf<char_type, traits_type> __filebuf_type;
612 typedef basic_ostream<char_type, traits_type> __ostream_type;
614 private:
615 /**
616 * @if maint
617 * @doctodo
618 * @endif
619 */
620 __filebuf_type _M_filebuf;
622 public:
623 // Constructors:
624 /**
625 * @brief Default constructor.
626 *
627 * Initializes @c sb using its default constructor, and passes
628 * @c &sb to the base class initializer. Does not open any files
629 * (you haven't given it a filename to open).
630 */
631 basic_ofstream(): __ostream_type(), _M_filebuf()
632 { this->init(&_M_filebuf); }
634 /**
635 * @brief Create an output file stream.
636 * @param s Null terminated string specifying the filename.
637 * @param mode Open file in specified mode (see std::ios_base).
638 *
639 * @c ios_base::out|ios_base::trunc is automatically included in
640 * @a mode.
641 *
642 * Tip: When using std::string to hold the filename, you must use
643 * .c_str() before passing it to this constructor.
644 */
645 explicit
646 basic_ofstream(const char* __s,
647 ios_base::openmode __mode = ios_base::out|ios_base::trunc)
648 : __ostream_type(), _M_filebuf()
649 {
650 this->init(&_M_filebuf);
651 this->open(__s, __mode);
652 }
654 /**
655 * @brief The destructor does nothing.
656 *
657 * The file is closed by the filebuf object, not the formatting
658 * stream.
659 */
660 ~basic_ofstream()
661 { }
663 // Members:
664 /**
665 * @brief Accessing the underlying buffer.
666 * @return The current basic_filebuf buffer.
667 *
668 * This hides both signatures of std::basic_ios::rdbuf().
669 */
670 __filebuf_type*
671 rdbuf() const
672 { return const_cast<__filebuf_type*>(&_M_filebuf); }
674 /**
675 * @brief Wrapper to test for an open file.
676 * @return @c rdbuf()->is_open()
677 */
678 bool
679 is_open() { return _M_filebuf.is_open(); }
681 /**
682 * @brief Opens an external file.
683 * @param s The name of the file.
684 * @param mode The open mode flags.
685 *
686 * Calls @c std::basic_filebuf::open(s,mode|out|trunc). If that
687 * function fails, @c failbit is set in the stream's error state.
688 *
689 * Tip: When using std::string to hold the filename, you must use
690 * .c_str() before passing it to this constructor.
691 */
692 void
693 open(const char* __s,
694 ios_base::openmode __mode = ios_base::out | ios_base::trunc)
695 {
696 if (!_M_filebuf.open(__s, __mode | ios_base::out))
697 this->setstate(ios_base::failbit);
698 }
700 /**
701 * @brief Close the file.
702 *
703 * Calls @c std::basic_filebuf::close(). If that function
704 * fails, @c failbit is set in the stream's error state.
705 */
706 void
707 close()
708 {
709 if (!_M_filebuf.close())
710 this->setstate(ios_base::failbit);
711 }
712 };
715 // [27.8.1.11] Template class basic_fstream
716 /**
717 * @brief Controlling intput and output for files.
718 *
719 * This class supports reading from and writing to named files, using
720 * the inherited functions from std::basic_iostream. To control the
721 * associated sequence, an instance of std::basic_filebuf is used, which
722 * this page refers to as @c sb.
723 */
724 template<typename _CharT, typename _Traits>
725 class basic_fstream : public basic_iostream<_CharT, _Traits>
726 {
727 public:
728 // Types:
729 typedef _CharT char_type;
730 typedef _Traits traits_type;
731 typedef typename traits_type::int_type int_type;
732 typedef typename traits_type::pos_type pos_type;
733 typedef typename traits_type::off_type off_type;
735 // Non-standard types:
736 typedef basic_filebuf<char_type, traits_type> __filebuf_type;
737 typedef basic_ios<char_type, traits_type> __ios_type;
738 typedef basic_iostream<char_type, traits_type> __iostream_type;
740 private:
741 /**
742 * @if maint
743 * @doctodo
744 * @endif
745 */
746 __filebuf_type _M_filebuf;
748 public:
749 // Constructors/destructor:
750 /**
751 * @brief Default constructor.
752 *
753 * Initializes @c sb using its default constructor, and passes
754 * @c &sb to the base class initializer. Does not open any files
755 * (you haven't given it a filename to open).
756 */
757 basic_fstream()
758 : __iostream_type(), _M_filebuf()
759 { this->init(&_M_filebuf); }
761 /**
762 * @brief Create an input/output file stream.
763 * @param s Null terminated string specifying the filename.
764 * @param mode Open file in specified mode (see std::ios_base).
765 *
766 * Tip: When using std::string to hold the filename, you must use
767 * .c_str() before passing it to this constructor.
768 */
769 explicit
770 basic_fstream(const char* __s,
771 ios_base::openmode __mode = ios_base::in | ios_base::out)
772 : __iostream_type(NULL), _M_filebuf()
773 {
774 this->init(&_M_filebuf);
775 this->open(__s, __mode);
776 }
778 /**
779 * @brief The destructor does nothing.
780 *
781 * The file is closed by the filebuf object, not the formatting
782 * stream.
783 */
784 ~basic_fstream()
785 { }
787 // Members:
788 /**
789 * @brief Accessing the underlying buffer.
790 * @return The current basic_filebuf buffer.
791 *
792 * This hides both signatures of std::basic_ios::rdbuf().
793 */
794 __filebuf_type*
795 rdbuf() const
796 { return const_cast<__filebuf_type*>(&_M_filebuf); }
798 /**
799 * @brief Wrapper to test for an open file.
800 * @return @c rdbuf()->is_open()
801 */
802 bool
803 is_open() { return _M_filebuf.is_open(); }
805 /**
806 * @brief Opens an external file.
807 * @param s The name of the file.
808 * @param mode The open mode flags.
809 *
810 * Calls @c std::basic_filebuf::open(s,mode). If that
811 * function fails, @c failbit is set in the stream's error state.
812 *
813 * Tip: When using std::string to hold the filename, you must use
814 * .c_str() before passing it to this constructor.
815 */
816 void
817 open(const char* __s,
818 ios_base::openmode __mode = ios_base::in | ios_base::out)
819 {
820 if (!_M_filebuf.open(__s, __mode))
821 this->setstate(ios_base::failbit);
822 }
824 /**
825 * @brief Close the file.
826 *
827 * Calls @c std::basic_filebuf::close(). If that function
828 * fails, @c failbit is set in the stream's error state.
829 */
830 void
831 close()
832 {
833 if (!_M_filebuf.close())
834 this->setstate(ios_base::failbit);
835 }
836 };
837 } // namespace std
839 #ifndef _GLIBCXX_EXPORT_TEMPLATE
840 # include <bits/fstream.tcc>
841 #endif
843 #endif /* _GLIBCXX_FSTREAM */