1 // File based streams -*- C++ -*-
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003
4 // Free Software Foundation, Inc.
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)
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,
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.
32 // ISO C++ 14882: 27.8 File-based streams
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.
40 #ifndef _GLIBCXX_FSTREAM
41 #define _GLIBCXX_FSTREAM 1
43 #pragma GCC system_header
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>
54 // [27.8.1.1] template class basic_filebuf
56 * @brief The actual work of input and output (for files).
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.
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>
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;
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;
92 friend class ios_base; // For sync_with_stdio.
96 // MT lock inherited from libio or other low-level io library.
114 * Place to stash in || out || in | out settings for current filebuf.
117 ios_base::openmode _M_mode;
119 // Beginning state type for codecvt.
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
135 __state_type _M_state_cur;
137 // Not used for output. During input, the state that corresponds
138 // to eback() and _M_ext_buf.
144 __state_type _M_state_last;
148 * Pointer to the beginning of internal buffer.
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
162 // Set iff _M_buf is allocated memory from _M_allocate_internal_buffer.
168 bool _M_buf_allocated;
172 * _M_reading == false && _M_writing == false for 'uncommitted' mode;
173 * _M_reading == true for 'read' mode;
174 * _M_writing == true for 'write' mode;
176 * NB: _M_reading == true && _M_writing == true is unused.
185 * Necessary bits for putback buffer management.
187 * @note pbacks of over one character are not currently supported.
191 char_type* _M_pback_cur_save;
192 char_type* _M_pback_end_save;
196 // Cached codecvt facet.
197 const __codecvt_type* _M_codecvt;
201 * Buffer for external characters. Used for input when
202 * codecvt::always_noconv() == false. When valid, this corresponds
210 * Size of buffer held by _M_ext_buf.
213 streamsize _M_ext_buf_size;
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().
222 const char* _M_ext_next;
227 * Initializes pback buffers, and moves normal buffers to safety.
229 * _M_in_cur has already been moved back
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;
246 * Deactivates pback buffer contents, and restores normal buffer.
248 * The pback buffer has only moved forward.
252 _M_destroy_pback() throw()
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;
264 // Constructors/destructor:
266 * @brief Does not open any files.
268 * The default constructor initializes the parent class using its
274 * @brief The destructor closes the file first.
282 * @brief Returns true if the external file is open.
285 is_open() const throw() { return _M_file.is_open(); }
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
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
297 * [Table 92 gives the relation between openmode combinations and the
298 * equivalent fopen() flags, but the table has not been copied yet.]
301 open(const char* __s, ios_base::openmode __mode);
304 * @brief Closes the currently associated file.
305 * @return @c this on success, NULL on failure
307 * If no file is currently open, this function immediately fails.
309 * If a "put buffer area" exists, @c overflow(eof) is called to flush
310 * all the characters. The file is then closed.
312 * If any operations fail, this function also fails.
324 _M_allocate_internal_buffer();
332 _M_destroy_internal_buffer() throw();
334 // [27.8.1.4] overridden virtual functions
335 // [documentation is inherited]
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]
348 // [documentation is inherited]
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
358 // Consume some sequence of the characters in the pending sequence.
365 overflow(int_type __c = _Traits::eof());
367 // Convert internal byte sequence to external, char-based
368 // sequence via codecvt.
375 _M_convert_to_external(char_type*, streamsize);
378 * @brief Manipulates the buffer.
379 * @param s Pointer to a buffer area.
380 * @param n Size of @a s.
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
386 * http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2
389 virtual __streambuf_type*
390 setbuf(char_type* __s, streamsize __n);
392 // [documentation is inherited]
394 seekoff(off_type __off, ios_base::seekdir __way,
395 ios_base::openmode __mode = ios_base::in | ios_base::out);
397 // [documentation is inherited]
399 seekpos(pos_type __pos,
400 ios_base::openmode __mode = ios_base::in | ios_base::out);
402 // Common code for seekoff and seekpos
409 _M_seek(off_type __off, ios_base::seekdir __way, __state_type __state);
411 // [documentation is inherited]
415 // [documentation is inherited]
417 imbue(const locale& __loc);
419 // [documentation is inherited]
421 xsgetn(char_type* __s, streamsize __n)
423 // Clear out pback buffer before going on to the real deal...
424 streamsize __ret = 0;
425 if (this->_M_pback_init)
427 if (__n && this->gptr() == this->eback())
429 *__s++ = *this->gptr();
436 __ret += __streambuf_type::xsgetn(__s, __n - __ret);
440 // [documentation is inherited]
442 xsputn(const char_type* __s, streamsize __n);
444 // Flushes output buffer, then writes unshift sequence.
451 _M_terminate_output();
455 * This function sets the pointers of the internal buffer, both get
456 * and put areas. Typically:
458 * __off == egptr() - eback() upon underflow/uflow ('read' mode);
459 * __off == 0 upon overflow ('write' mode);
460 * __off == -1 upon open, setbuf, seekoff/pos ('uncommitted' mode).
462 * NB: epptr() - pbase() == _M_buf_size - 1, since _M_buf_size
463 * reflects the actual allocated memory and the last cell is reserved
464 * for the overflow char of a full put area.
468 _M_set_buffer(streamsize __off)
470 const bool __testin = this->_M_mode & ios_base::in;
471 const bool __testout = this->_M_mode & ios_base::out;
473 if (__testin && __off > 0)
474 this->setg(this->_M_buf, this->_M_buf, this->_M_buf + __off);
476 this->setg(this->_M_buf, this->_M_buf, this->_M_buf);
478 if (__testout && __off == 0 && this->_M_buf_size > 1 )
479 this->setp(this->_M_buf, this->_M_buf + this->_M_buf_size - 1);
481 this->setp(NULL, NULL);
485 // [27.8.1.5] Template class basic_ifstream
487 * @brief Controlling input for files.
489 * This class supports reading from named files, using the inherited
490 * functions from std::basic_istream. To control the associated
491 * sequence, an instance of std::basic_filebuf is used, which this page
492 * refers to as @c sb.
494 template<typename _CharT, typename _Traits>
495 class basic_ifstream : public basic_istream<_CharT, _Traits>
499 typedef _CharT char_type;
500 typedef _Traits traits_type;
501 typedef typename traits_type::int_type int_type;
502 typedef typename traits_type::pos_type pos_type;
503 typedef typename traits_type::off_type off_type;
505 // Non-standard types:
506 typedef basic_filebuf<char_type, traits_type> __filebuf_type;
507 typedef basic_istream<char_type, traits_type> __istream_type;
515 __filebuf_type _M_filebuf;
518 // Constructors/Destructors:
520 * @brief Default constructor.
522 * Initializes @c sb using its default constructor, and passes
523 * @c &sb to the base class initializer. Does not open any files
524 * (you haven't given it a filename to open).
526 basic_ifstream() : __istream_type(), _M_filebuf()
527 { this->init(&_M_filebuf); }
530 * @brief Create an input file stream.
531 * @param s Null terminated string specifying the filename.
532 * @param mode Open file in specified mode (see std::ios_base).
534 * @c ios_base::in is automatically included in @a mode.
536 * Tip: When using std::string to hold the filename, you must use
537 * .c_str() before passing it to this constructor.
540 basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in)
541 : __istream_type(), _M_filebuf()
543 this->init(&_M_filebuf);
544 this->open(__s, __mode);
548 * @brief The destructor does nothing.
550 * The file is closed by the filebuf object, not the formatting
558 * @brief Accessing the underlying buffer.
559 * @return The current basic_filebuf buffer.
561 * This hides both signatures of std::basic_ios::rdbuf().
565 { return const_cast<__filebuf_type*>(&_M_filebuf); }
568 * @brief Wrapper to test for an open file.
569 * @return @c rdbuf()->is_open()
572 is_open() { return _M_filebuf.is_open(); }
575 * @brief Opens an external file.
576 * @param s The name of the file.
577 * @param mode The open mode flags.
579 * Calls @c std::basic_filebuf::open(s,mode|in). If that function
580 * fails, @c failbit is set in the stream's error state.
582 * Tip: When using std::string to hold the filename, you must use
583 * .c_str() before passing it to this constructor.
586 open(const char* __s, ios_base::openmode __mode = ios_base::in)
588 if (!_M_filebuf.open(__s, __mode | ios_base::in))
589 this->setstate(ios_base::failbit);
593 * @brief Close the file.
595 * Calls @c std::basic_filebuf::close(). If that function
596 * fails, @c failbit is set in the stream's error state.
601 if (!_M_filebuf.close())
602 this->setstate(ios_base::failbit);
607 // [27.8.1.8] Template class basic_ofstream
609 * @brief Controlling output for files.
611 * This class supports reading from named files, using the inherited
612 * functions from std::basic_ostream. To control the associated
613 * sequence, an instance of std::basic_filebuf is used, which this page
614 * refers to as @c sb.
616 template<typename _CharT, typename _Traits>
617 class basic_ofstream : public basic_ostream<_CharT,_Traits>
621 typedef _CharT char_type;
622 typedef _Traits traits_type;
623 typedef typename traits_type::int_type int_type;
624 typedef typename traits_type::pos_type pos_type;
625 typedef typename traits_type::off_type off_type;
627 // Non-standard types:
628 typedef basic_filebuf<char_type, traits_type> __filebuf_type;
629 typedef basic_ostream<char_type, traits_type> __ostream_type;
637 __filebuf_type _M_filebuf;
642 * @brief Default constructor.
644 * Initializes @c sb using its default constructor, and passes
645 * @c &sb to the base class initializer. Does not open any files
646 * (you haven't given it a filename to open).
648 basic_ofstream(): __ostream_type(), _M_filebuf()
649 { this->init(&_M_filebuf); }
652 * @brief Create an output file stream.
653 * @param s Null terminated string specifying the filename.
654 * @param mode Open file in specified mode (see std::ios_base).
656 * @c ios_base::out|ios_base::trunc is automatically included in
659 * Tip: When using std::string to hold the filename, you must use
660 * .c_str() before passing it to this constructor.
663 basic_ofstream(const char* __s,
664 ios_base::openmode __mode = ios_base::out|ios_base::trunc)
665 : __ostream_type(), _M_filebuf()
667 this->init(&_M_filebuf);
668 this->open(__s, __mode);
672 * @brief The destructor does nothing.
674 * The file is closed by the filebuf object, not the formatting
682 * @brief Accessing the underlying buffer.
683 * @return The current basic_filebuf buffer.
685 * This hides both signatures of std::basic_ios::rdbuf().
689 { return const_cast<__filebuf_type*>(&_M_filebuf); }
692 * @brief Wrapper to test for an open file.
693 * @return @c rdbuf()->is_open()
696 is_open() { return _M_filebuf.is_open(); }
699 * @brief Opens an external file.
700 * @param s The name of the file.
701 * @param mode The open mode flags.
703 * Calls @c std::basic_filebuf::open(s,mode|out|trunc). If that
704 * function fails, @c failbit is set in the stream's error state.
706 * Tip: When using std::string to hold the filename, you must use
707 * .c_str() before passing it to this constructor.
710 open(const char* __s,
711 ios_base::openmode __mode = ios_base::out | ios_base::trunc)
713 if (!_M_filebuf.open(__s, __mode | ios_base::out))
714 this->setstate(ios_base::failbit);
718 * @brief Close the file.
720 * Calls @c std::basic_filebuf::close(). If that function
721 * fails, @c failbit is set in the stream's error state.
726 if (!_M_filebuf.close())
727 this->setstate(ios_base::failbit);
732 // [27.8.1.11] Template class basic_fstream
734 * @brief Controlling intput and output for files.
736 * This class supports reading from and writing to named files, using
737 * the inherited functions from std::basic_iostream. To control the
738 * associated sequence, an instance of std::basic_filebuf is used, which
739 * this page refers to as @c sb.
741 template<typename _CharT, typename _Traits>
742 class basic_fstream : public basic_iostream<_CharT, _Traits>
746 typedef _CharT char_type;
747 typedef _Traits traits_type;
748 typedef typename traits_type::int_type int_type;
749 typedef typename traits_type::pos_type pos_type;
750 typedef typename traits_type::off_type off_type;
752 // Non-standard types:
753 typedef basic_filebuf<char_type, traits_type> __filebuf_type;
754 typedef basic_ios<char_type, traits_type> __ios_type;
755 typedef basic_iostream<char_type, traits_type> __iostream_type;
763 __filebuf_type _M_filebuf;
766 // Constructors/destructor:
768 * @brief Default constructor.
770 * Initializes @c sb using its default constructor, and passes
771 * @c &sb to the base class initializer. Does not open any files
772 * (you haven't given it a filename to open).
775 : __iostream_type(), _M_filebuf()
776 { this->init(&_M_filebuf); }
779 * @brief Create an input/output file stream.
780 * @param s Null terminated string specifying the filename.
781 * @param mode Open file in specified mode (see std::ios_base).
783 * Tip: When using std::string to hold the filename, you must use
784 * .c_str() before passing it to this constructor.
787 basic_fstream(const char* __s,
788 ios_base::openmode __mode = ios_base::in | ios_base::out)
789 : __iostream_type(NULL), _M_filebuf()
791 this->init(&_M_filebuf);
792 this->open(__s, __mode);
796 * @brief The destructor does nothing.
798 * The file is closed by the filebuf object, not the formatting
806 * @brief Accessing the underlying buffer.
807 * @return The current basic_filebuf buffer.
809 * This hides both signatures of std::basic_ios::rdbuf().
813 { return const_cast<__filebuf_type*>(&_M_filebuf); }
816 * @brief Wrapper to test for an open file.
817 * @return @c rdbuf()->is_open()
820 is_open() { return _M_filebuf.is_open(); }
823 * @brief Opens an external file.
824 * @param s The name of the file.
825 * @param mode The open mode flags.
827 * Calls @c std::basic_filebuf::open(s,mode). If that
828 * function fails, @c failbit is set in the stream's error state.
830 * Tip: When using std::string to hold the filename, you must use
831 * .c_str() before passing it to this constructor.
834 open(const char* __s,
835 ios_base::openmode __mode = ios_base::in | ios_base::out)
837 if (!_M_filebuf.open(__s, __mode))
838 this->setstate(ios_base::failbit);
842 * @brief Close the file.
844 * Calls @c std::basic_filebuf::close(). If that function
845 * fails, @c failbit is set in the stream's error state.
850 if (!_M_filebuf.close())
851 this->setstate(ios_base::failbit);
856 #ifndef _GLIBCXX_EXPORT_TEMPLATE
857 # include <bits/fstream.tcc>
860 #endif /* _GLIBCXX_FSTREAM */