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e1e0016d | 1 | // Stream buffer classes -*- C++ -*- |
01dd2c6c | 2 | |
f1717362 | 3 | // Copyright (C) 1997-2016 Free Software Foundation, Inc. |
01dd2c6c | 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 | |
6bc9506f | 8 | // Free Software Foundation; either version 3, or (at your option) |
01dd2c6c | 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 | ||
6bc9506f | 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/>. | |
01dd2c6c | 24 | |
5846aeac | 25 | /** @file include/streambuf |
b2a66747 | 26 | * This is a Standard C++ Library header. |
78ee80ac | 27 | */ |
28 | ||
944beac5 | 29 | // |
30 | // ISO C++ 14882: 27.5 Stream buffers | |
31 | // | |
32 | ||
81e48263 | 33 | #ifndef _GLIBXX_STREAMBUF |
34 | #define _GLIBXX_STREAMBUF 1 | |
e1e0016d | 35 | |
36 | #pragma GCC system_header | |
37 | ||
38 | #include <bits/c++config.h> | |
39 | #include <iosfwd> | |
e1e0016d | 40 | #include <bits/localefwd.h> |
41 | #include <bits/ios_base.h> | |
b8fe296d | 42 | #include <bits/cpp_type_traits.h> |
9acda962 | 43 | #include <ext/type_traits.h> |
e1e0016d | 44 | |
2948dd21 | 45 | namespace std _GLIBCXX_VISIBILITY(default) |
46 | { | |
47 | _GLIBCXX_BEGIN_NAMESPACE_VERSION | |
1069247d | 48 | |
e1e0016d | 49 | template<typename _CharT, typename _Traits> |
50 | streamsize | |
b8fe296d | 51 | __copy_streambufs_eof(basic_streambuf<_CharT, _Traits>*, |
52 | basic_streambuf<_CharT, _Traits>*, bool&); | |
53 | ||
ce705c0a | 54 | /** |
55 | * @brief The actual work of input and output (interface). | |
add48425 | 56 | * @ingroup io |
ce705c0a | 57 | * |
7184845c | 58 | * @tparam _CharT Type of character stream. |
59 | * @tparam _Traits Traits for character type, defaults to | |
60 | * char_traits<_CharT>. | |
61 | * | |
ce705c0a | 62 | * This is a base class. Derived stream buffers each control a |
63 | * pair of character sequences: one for input, and one for output. | |
64 | * | |
65 | * Section [27.5.1] of the standard describes the requirements and | |
66 | * behavior of stream buffer classes. That section (three paragraphs) | |
67 | * is reproduced here, for simplicity and accuracy. | |
68 | * | |
69 | * -# Stream buffers can impose various constraints on the sequences | |
70 | * they control. Some constraints are: | |
71 | * - The controlled input sequence can be not readable. | |
72 | * - The controlled output sequence can be not writable. | |
73 | * - The controlled sequences can be associated with the contents of | |
74 | * other representations for character sequences, such as external | |
75 | * files. | |
76 | * - The controlled sequences can support operations @e directly to or | |
77 | * from associated sequences. | |
78 | * - The controlled sequences can impose limitations on how the | |
79 | * program can read characters from a sequence, write characters to | |
80 | * a sequence, put characters back into an input sequence, or alter | |
81 | * the stream position. | |
82 | * . | |
83 | * -# Each sequence is characterized by three pointers which, if non-null, | |
84 | * all point into the same @c charT array object. The array object | |
85 | * represents, at any moment, a (sub)sequence of characters from the | |
86 | * sequence. Operations performed on a sequence alter the values | |
87 | * stored in these pointers, perform reads and writes directly to or | |
72117d76 | 88 | * from associated sequences, and alter <em>the stream position</em> and |
ce705c0a | 89 | * conversion state as needed to maintain this subsequence relationship. |
90 | * The three pointers are: | |
91 | * - the <em>beginning pointer</em>, or lowest element address in the | |
92 | * array (called @e xbeg here); | |
93 | * - the <em>next pointer</em>, or next element address that is a | |
94 | * current candidate for reading or writing (called @e xnext here); | |
95 | * - the <em>end pointer</em>, or first element address beyond the | |
96 | * end of the array (called @e xend here). | |
97 | * . | |
98 | * -# The following semantic constraints shall always apply for any set | |
99 | * of three pointers for a sequence, using the pointer names given | |
100 | * immediately above: | |
101 | * - If @e xnext is not a null pointer, then @e xbeg and @e xend shall | |
102 | * also be non-null pointers into the same @c charT array, as | |
103 | * described above; otherwise, @e xbeg and @e xend shall also be null. | |
104 | * - If @e xnext is not a null pointer and @e xnext < @e xend for an | |
105 | * output sequence, then a <em>write position</em> is available. | |
106 | * In this case, @e *xnext shall be assignable as the next element | |
107 | * to write (to put, or to store a character value, into the sequence). | |
108 | * - If @e xnext is not a null pointer and @e xbeg < @e xnext for an | |
109 | * input sequence, then a <em>putback position</em> is available. | |
110 | * In this case, @e xnext[-1] shall have a defined value and is the | |
111 | * next (preceding) element to store a character that is put back | |
112 | * into the input sequence. | |
113 | * - If @e xnext is not a null pointer and @e xnext< @e xend for an | |
114 | * input sequence, then a <em>read position</em> is available. | |
115 | * In this case, @e *xnext shall have a defined value and is the | |
116 | * next element to read (to get, or to obtain a character value, | |
117 | * from the sequence). | |
118 | */ | |
e1e0016d | 119 | template<typename _CharT, typename _Traits> |
385aec5a | 120 | class basic_streambuf |
e1e0016d | 121 | { |
122 | public: | |
ce705c0a | 123 | //@{ |
124 | /** | |
125 | * These are standard types. They permit a standardized way of | |
380449cf | 126 | * referring to names of (or names dependent on) the template |
ce705c0a | 127 | * parameters, which are specific to the implementation. |
128 | */ | |
e1e0016d | 129 | typedef _CharT char_type; |
130 | typedef _Traits traits_type; | |
131 | typedef typename traits_type::int_type int_type; | |
132 | typedef typename traits_type::pos_type pos_type; | |
133 | typedef typename traits_type::off_type off_type; | |
ce705c0a | 134 | //@} |
135 | ||
136 | //@{ | |
0aeadebf | 137 | /// This is a non-standard type. |
e1e0016d | 138 | typedef basic_streambuf<char_type, traits_type> __streambuf_type; |
ce705c0a | 139 | //@} |
385aec5a | 140 | |
e1e0016d | 141 | friend class basic_ios<char_type, traits_type>; |
142 | friend class basic_istream<char_type, traits_type>; | |
143 | friend class basic_ostream<char_type, traits_type>; | |
144 | friend class istreambuf_iterator<char_type, traits_type>; | |
145 | friend class ostreambuf_iterator<char_type, traits_type>; | |
146 | ||
147 | friend streamsize | |
8ad4c4ec | 148 | __copy_streambufs_eof<>(basic_streambuf*, basic_streambuf*, bool&); |
b8fe296d | 149 | |
0960c06d | 150 | template<bool _IsMove, typename _CharT2> |
385aec5a | 151 | friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, |
9acda962 | 152 | _CharT2*>::__type |
0960c06d | 153 | __copy_move_a2(istreambuf_iterator<_CharT2>, |
154 | istreambuf_iterator<_CharT2>, _CharT2*); | |
b8fe296d | 155 | |
156 | template<typename _CharT2> | |
9acda962 | 157 | friend typename __gnu_cxx::__enable_if<__is_char<_CharT2>::__value, |
158 | istreambuf_iterator<_CharT2> >::__type | |
b8fe296d | 159 | find(istreambuf_iterator<_CharT2>, istreambuf_iterator<_CharT2>, |
6b9cb58c | 160 | const _CharT2&); |
b8fe296d | 161 | |
bc1c8aef | 162 | template<typename _CharT2, typename _Traits2> |
163 | friend basic_istream<_CharT2, _Traits2>& | |
164 | operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*); | |
b8fe296d | 165 | |
bc1c8aef | 166 | template<typename _CharT2, typename _Traits2, typename _Alloc> |
167 | friend basic_istream<_CharT2, _Traits2>& | |
168 | operator>>(basic_istream<_CharT2, _Traits2>&, | |
169 | basic_string<_CharT2, _Traits2, _Alloc>&); | |
b8fe296d | 170 | |
5712dd7d | 171 | template<typename _CharT2, typename _Traits2, typename _Alloc> |
172 | friend basic_istream<_CharT2, _Traits2>& | |
173 | getline(basic_istream<_CharT2, _Traits2>&, | |
174 | basic_string<_CharT2, _Traits2, _Alloc>&, _CharT2); | |
175 | ||
e1e0016d | 176 | protected: |
8ad4c4ec | 177 | /* |
ce705c0a | 178 | * This is based on _IO_FILE, just reordered to be more consistent, |
179 | * and is intended to be the most minimal abstraction for an | |
180 | * internal buffer. | |
181 | * - get == input == read | |
182 | * - put == output == write | |
ce705c0a | 183 | */ |
8ad4c4ec | 184 | char_type* _M_in_beg; ///< Start of get area. |
185 | char_type* _M_in_cur; ///< Current read area. | |
186 | char_type* _M_in_end; ///< End of get area. | |
187 | char_type* _M_out_beg; ///< Start of put area. | |
188 | char_type* _M_out_cur; ///< Current put area. | |
189 | char_type* _M_out_end; ///< End of put area. | |
943886d6 | 190 | |
0aeadebf | 191 | /// Current locale setting. |
385aec5a | 192 | locale _M_buf_locale; |
e1e0016d | 193 | |
e1e0016d | 194 | public: |
ce705c0a | 195 | /// Destructor deallocates no buffer space. |
385aec5a | 196 | virtual |
197 | ~basic_streambuf() | |
212d2161 | 198 | { } |
e1e0016d | 199 | |
ce705c0a | 200 | // [27.5.2.2.1] locales |
201 | /** | |
202 | * @brief Entry point for imbue(). | |
e12e4f3b | 203 | * @param __loc The new locale. |
ce705c0a | 204 | * @return The previous locale. |
205 | * | |
e12e4f3b | 206 | * Calls the derived imbue(__loc). |
ce705c0a | 207 | */ |
385aec5a | 208 | locale |
e12e4f3b | 209 | pubimbue(const locale& __loc) |
e1e0016d | 210 | { |
211 | locale __tmp(this->getloc()); | |
212 | this->imbue(__loc); | |
fad557f3 | 213 | _M_buf_locale = __loc; |
e1e0016d | 214 | return __tmp; |
215 | } | |
216 | ||
ce705c0a | 217 | /** |
218 | * @brief Locale access. | |
219 | * @return The current locale in effect. | |
220 | * | |
221 | * If pubimbue(loc) has been called, then the most recent @c loc | |
222 | * is returned. Otherwise the global locale in effect at the time | |
223 | * of construction is returned. | |
224 | */ | |
385aec5a | 225 | locale |
e1e0016d | 226 | getloc() const |
385aec5a | 227 | { return _M_buf_locale; } |
e1e0016d | 228 | |
ce705c0a | 229 | // [27.5.2.2.2] buffer management and positioning |
230 | //@{ | |
231 | /** | |
232 | * @brief Entry points for derived buffer functions. | |
233 | * | |
234 | * The public versions of @c pubfoo dispatch to the protected | |
235 | * derived @c foo member functions, passing the arguments (if any) | |
236 | * and returning the result unchanged. | |
237 | */ | |
8ad4c4ec | 238 | basic_streambuf* |
385aec5a | 239 | pubsetbuf(char_type* __s, streamsize __n) |
e1e0016d | 240 | { return this->setbuf(__s, __n); } |
241 | ||
e12e4f3b | 242 | /** |
243 | * @brief Alters the stream position. | |
244 | * @param __off Offset. | |
245 | * @param __way Value for ios_base::seekdir. | |
246 | * @param __mode Value for ios_base::openmode. | |
247 | * | |
248 | * Calls virtual seekoff function. | |
249 | */ | |
385aec5a | 250 | pos_type |
251 | pubseekoff(off_type __off, ios_base::seekdir __way, | |
e1e0016d | 252 | ios_base::openmode __mode = ios_base::in | ios_base::out) |
253 | { return this->seekoff(__off, __way, __mode); } | |
254 | ||
e12e4f3b | 255 | /** |
256 | * @brief Alters the stream position. | |
257 | * @param __sp Position | |
258 | * @param __mode Value for ios_base::openmode. | |
259 | * | |
260 | * Calls virtual seekpos function. | |
261 | */ | |
385aec5a | 262 | pos_type |
e1e0016d | 263 | pubseekpos(pos_type __sp, |
264 | ios_base::openmode __mode = ios_base::in | ios_base::out) | |
265 | { return this->seekpos(__sp, __mode); } | |
266 | ||
e12e4f3b | 267 | /** |
268 | * @brief Calls virtual sync function. | |
269 | */ | |
385aec5a | 270 | int |
e1e0016d | 271 | pubsync() { return this->sync(); } |
ce705c0a | 272 | //@} |
273 | ||
274 | // [27.5.2.2.3] get area | |
275 | /** | |
276 | * @brief Looking ahead into the stream. | |
277 | * @return The number of characters available. | |
278 | * | |
279 | * If a read position is available, returns the number of characters | |
280 | * available for reading before the buffer must be refilled. | |
281 | * Otherwise returns the derived @c showmanyc(). | |
282 | */ | |
385aec5a | 283 | streamsize |
284 | in_avail() | |
285 | { | |
a6bfe6ae | 286 | const streamsize __ret = this->egptr() - this->gptr(); |
13a05508 | 287 | return __ret ? __ret : this->showmanyc(); |
e1e0016d | 288 | } |
289 | ||
ce705c0a | 290 | /** |
291 | * @brief Getting the next character. | |
292 | * @return The next character, or eof. | |
293 | * | |
294 | * Calls @c sbumpc(), and if that function returns | |
295 | * @c traits::eof(), so does this function. Otherwise, @c sgetc(). | |
296 | */ | |
385aec5a | 297 | int_type |
e1e0016d | 298 | snextc() |
299 | { | |
e99fa449 | 300 | int_type __ret = traits_type::eof(); |
385aec5a | 301 | if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(), |
bf2f8039 | 302 | __ret), true)) |
e99fa449 | 303 | __ret = this->sgetc(); |
304 | return __ret; | |
e1e0016d | 305 | } |
306 | ||
ce705c0a | 307 | /** |
308 | * @brief Getting the next character. | |
309 | * @return The next character, or eof. | |
310 | * | |
311 | * If the input read position is available, returns that character | |
312 | * and increments the read pointer, otherwise calls and returns | |
313 | * @c uflow(). | |
314 | */ | |
385aec5a | 315 | int_type |
bf2f8039 | 316 | sbumpc() |
317 | { | |
318 | int_type __ret; | |
319 | if (__builtin_expect(this->gptr() < this->egptr(), true)) | |
320 | { | |
321 | __ret = traits_type::to_int_type(*this->gptr()); | |
322 | this->gbump(1); | |
323 | } | |
385aec5a | 324 | else |
bf2f8039 | 325 | __ret = this->uflow(); |
326 | return __ret; | |
327 | } | |
e1e0016d | 328 | |
ce705c0a | 329 | /** |
330 | * @brief Getting the next character. | |
331 | * @return The next character, or eof. | |
332 | * | |
333 | * If the input read position is available, returns that character, | |
385aec5a | 334 | * otherwise calls and returns @c underflow(). Does not move the |
ce705c0a | 335 | * read position after fetching the character. |
336 | */ | |
385aec5a | 337 | int_type |
e1e0016d | 338 | sgetc() |
339 | { | |
4eea38c0 | 340 | int_type __ret; |
bf2f8039 | 341 | if (__builtin_expect(this->gptr() < this->egptr(), true)) |
a6bfe6ae | 342 | __ret = traits_type::to_int_type(*this->gptr()); |
385aec5a | 343 | else |
4eea38c0 | 344 | __ret = this->underflow(); |
345 | return __ret; | |
e1e0016d | 346 | } |
347 | ||
ce705c0a | 348 | /** |
349 | * @brief Entry point for xsgetn. | |
e12e4f3b | 350 | * @param __s A buffer area. |
351 | * @param __n A count. | |
ce705c0a | 352 | * |
e12e4f3b | 353 | * Returns xsgetn(__s,__n). The effect is to fill @a __s[0] through |
354 | * @a __s[__n-1] with characters from the input sequence, if possible. | |
ce705c0a | 355 | */ |
385aec5a | 356 | streamsize |
e1e0016d | 357 | sgetn(char_type* __s, streamsize __n) |
358 | { return this->xsgetn(__s, __n); } | |
359 | ||
ce705c0a | 360 | // [27.5.2.2.4] putback |
361 | /** | |
362 | * @brief Pushing characters back into the input stream. | |
e12e4f3b | 363 | * @param __c The character to push back. |
ce705c0a | 364 | * @return The previous character, if possible. |
365 | * | |
e12e4f3b | 366 | * Similar to sungetc(), but @a __c is pushed onto the stream |
72117d76 | 367 | * instead of <em>the previous character.</em> If successful, |
368 | * the next character fetched from the input stream will be @a | |
e12e4f3b | 369 | * __c. |
ce705c0a | 370 | */ |
385aec5a | 371 | int_type |
bf2f8039 | 372 | sputbackc(char_type __c) |
373 | { | |
374 | int_type __ret; | |
375 | const bool __testpos = this->eback() < this->gptr(); | |
385aec5a | 376 | if (__builtin_expect(!__testpos || |
bf2f8039 | 377 | !traits_type::eq(__c, this->gptr()[-1]), false)) |
378 | __ret = this->pbackfail(traits_type::to_int_type(__c)); | |
385aec5a | 379 | else |
bf2f8039 | 380 | { |
381 | this->gbump(-1); | |
382 | __ret = traits_type::to_int_type(*this->gptr()); | |
383 | } | |
384 | return __ret; | |
385 | } | |
e1e0016d | 386 | |
ce705c0a | 387 | /** |
388 | * @brief Moving backwards in the input stream. | |
389 | * @return The previous character, if possible. | |
390 | * | |
72117d76 | 391 | * If a putback position is available, this function decrements |
392 | * the input pointer and returns that character. Otherwise, | |
393 | * calls and returns pbackfail(). The effect is to @a unget | |
394 | * the last character @a gotten. | |
ce705c0a | 395 | */ |
385aec5a | 396 | int_type |
bf2f8039 | 397 | sungetc() |
398 | { | |
399 | int_type __ret; | |
400 | if (__builtin_expect(this->eback() < this->gptr(), true)) | |
401 | { | |
402 | this->gbump(-1); | |
403 | __ret = traits_type::to_int_type(*this->gptr()); | |
404 | } | |
385aec5a | 405 | else |
bf2f8039 | 406 | __ret = this->pbackfail(); |
407 | return __ret; | |
408 | } | |
e1e0016d | 409 | |
ce705c0a | 410 | // [27.5.2.2.5] put area |
411 | /** | |
412 | * @brief Entry point for all single-character output functions. | |
e12e4f3b | 413 | * @param __c A character to output. |
414 | * @return @a __c, if possible. | |
ce705c0a | 415 | * |
416 | * One of two public output functions. | |
417 | * | |
418 | * If a write position is available for the output sequence (i.e., | |
e12e4f3b | 419 | * the buffer is not full), stores @a __c in that position, increments |
420 | * the position, and returns @c traits::to_int_type(__c). If a write | |
421 | * position is not available, returns @c overflow(__c). | |
ce705c0a | 422 | */ |
385aec5a | 423 | int_type |
bf2f8039 | 424 | sputc(char_type __c) |
425 | { | |
426 | int_type __ret; | |
427 | if (__builtin_expect(this->pptr() < this->epptr(), true)) | |
428 | { | |
429 | *this->pptr() = __c; | |
430 | this->pbump(1); | |
431 | __ret = traits_type::to_int_type(__c); | |
432 | } | |
433 | else | |
434 | __ret = this->overflow(traits_type::to_int_type(__c)); | |
435 | return __ret; | |
436 | } | |
e1e0016d | 437 | |
ce705c0a | 438 | /** |
439 | * @brief Entry point for all single-character output functions. | |
e12e4f3b | 440 | * @param __s A buffer read area. |
441 | * @param __n A count. | |
ce705c0a | 442 | * |
443 | * One of two public output functions. | |
444 | * | |
445 | * | |
e12e4f3b | 446 | * Returns xsputn(__s,__n). The effect is to write @a __s[0] through |
447 | * @a __s[__n-1] to the output sequence, if possible. | |
ce705c0a | 448 | */ |
385aec5a | 449 | streamsize |
e1e0016d | 450 | sputn(const char_type* __s, streamsize __n) |
451 | { return this->xsputn(__s, __n); } | |
452 | ||
453 | protected: | |
ce705c0a | 454 | /** |
455 | * @brief Base constructor. | |
456 | * | |
457 | * Only called from derived constructors, and sets up all the | |
458 | * buffer data to zero, including the pointers described in the | |
459 | * basic_streambuf class description. Note that, as a result, | |
460 | * - the class starts with no read nor write positions available, | |
461 | * - this is not an error | |
462 | */ | |
e1e0016d | 463 | basic_streambuf() |
385aec5a | 464 | : _M_in_beg(0), _M_in_cur(0), _M_in_end(0), |
6b7deda8 | 465 | _M_out_beg(0), _M_out_cur(0), _M_out_end(0), |
385aec5a | 466 | _M_buf_locale(locale()) |
e1e0016d | 467 | { } |
468 | ||
ce705c0a | 469 | // [27.5.2.3.1] get area access |
470 | //@{ | |
471 | /** | |
472 | * @brief Access to the get area. | |
473 | * | |
474 | * These functions are only available to other protected functions, | |
475 | * including derived classes. | |
476 | * | |
477 | * - eback() returns the beginning pointer for the input sequence | |
478 | * - gptr() returns the next pointer for the input sequence | |
479 | * - egptr() returns the end pointer for the input sequence | |
480 | */ | |
385aec5a | 481 | char_type* |
e1e0016d | 482 | eback() const { return _M_in_beg; } |
483 | ||
385aec5a | 484 | char_type* |
e1e0016d | 485 | gptr() const { return _M_in_cur; } |
486 | ||
385aec5a | 487 | char_type* |
e1e0016d | 488 | egptr() const { return _M_in_end; } |
ce705c0a | 489 | //@} |
490 | ||
491 | /** | |
492 | * @brief Moving the read position. | |
e12e4f3b | 493 | * @param __n The delta by which to move. |
ce705c0a | 494 | * |
495 | * This just advances the read position without returning any data. | |
496 | */ | |
385aec5a | 497 | void |
e1e0016d | 498 | gbump(int __n) { _M_in_cur += __n; } |
499 | ||
ce705c0a | 500 | /** |
501 | * @brief Setting the three read area pointers. | |
e12e4f3b | 502 | * @param __gbeg A pointer. |
503 | * @param __gnext A pointer. | |
504 | * @param __gend A pointer. | |
505 | * @post @a __gbeg == @c eback(), @a __gnext == @c gptr(), and | |
506 | * @a __gend == @c egptr() | |
ce705c0a | 507 | */ |
385aec5a | 508 | void |
e1e0016d | 509 | setg(char_type* __gbeg, char_type* __gnext, char_type* __gend) |
510 | { | |
511 | _M_in_beg = __gbeg; | |
512 | _M_in_cur = __gnext; | |
513 | _M_in_end = __gend; | |
e1e0016d | 514 | } |
515 | ||
ce705c0a | 516 | // [27.5.2.3.2] put area access |
517 | //@{ | |
518 | /** | |
519 | * @brief Access to the put area. | |
520 | * | |
521 | * These functions are only available to other protected functions, | |
522 | * including derived classes. | |
523 | * | |
524 | * - pbase() returns the beginning pointer for the output sequence | |
525 | * - pptr() returns the next pointer for the output sequence | |
526 | * - epptr() returns the end pointer for the output sequence | |
527 | */ | |
385aec5a | 528 | char_type* |
e1e0016d | 529 | pbase() const { return _M_out_beg; } |
530 | ||
385aec5a | 531 | char_type* |
e1e0016d | 532 | pptr() const { return _M_out_cur; } |
533 | ||
385aec5a | 534 | char_type* |
e1e0016d | 535 | epptr() const { return _M_out_end; } |
ce705c0a | 536 | //@} |
537 | ||
538 | /** | |
539 | * @brief Moving the write position. | |
e12e4f3b | 540 | * @param __n The delta by which to move. |
ce705c0a | 541 | * |
542 | * This just advances the write position without returning any data. | |
543 | */ | |
385aec5a | 544 | void |
e1e0016d | 545 | pbump(int __n) { _M_out_cur += __n; } |
546 | ||
ce705c0a | 547 | /** |
548 | * @brief Setting the three write area pointers. | |
e12e4f3b | 549 | * @param __pbeg A pointer. |
550 | * @param __pend A pointer. | |
551 | * @post @a __pbeg == @c pbase(), @a __pbeg == @c pptr(), and | |
552 | * @a __pend == @c epptr() | |
ce705c0a | 553 | */ |
385aec5a | 554 | void |
e1e0016d | 555 | setp(char_type* __pbeg, char_type* __pend) |
385aec5a | 556 | { |
557 | _M_out_beg = _M_out_cur = __pbeg; | |
7097a0ba | 558 | _M_out_end = __pend; |
e1e0016d | 559 | } |
560 | ||
ce705c0a | 561 | // [27.5.2.4] virtual functions |
562 | // [27.5.2.4.1] locales | |
563 | /** | |
564 | * @brief Changes translations. | |
e12e4f3b | 565 | * @param __loc A new locale. |
ce705c0a | 566 | * |
72117d76 | 567 | * Translations done during I/O which depend on the current |
568 | * locale are changed by this call. The standard adds, | |
569 | * <em>Between invocations of this function a class derived | |
570 | * from streambuf can safely cache results of calls to locale | |
571 | * functions and to members of facets so obtained.</em> | |
fad557f3 | 572 | * |
573 | * @note Base class version does nothing. | |
ce705c0a | 574 | */ |
385aec5a | 575 | virtual void |
576 | imbue(const locale& __loc) | |
fad557f3 | 577 | { } |
e1e0016d | 578 | |
ce705c0a | 579 | // [27.5.2.4.2] buffer management and positioning |
580 | /** | |
9fc1117c | 581 | * @brief Manipulates the buffer. |
ce705c0a | 582 | * |
583 | * Each derived class provides its own appropriate behavior. See | |
385aec5a | 584 | * the next-to-last paragraph of |
0698cdf1 | 585 | * https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering |
c53be2be | 586 | * for more on this function. |
ce705c0a | 587 | * |
588 | * @note Base class version does nothing, returns @c this. | |
589 | */ | |
385aec5a | 590 | virtual basic_streambuf<char_type,_Traits>* |
e1e0016d | 591 | setbuf(char_type*, streamsize) |
592 | { return this; } | |
385aec5a | 593 | |
ce705c0a | 594 | /** |
595 | * @brief Alters the stream positions. | |
596 | * | |
597 | * Each derived class provides its own appropriate behavior. | |
598 | * @note Base class version does nothing, returns a @c pos_type | |
599 | * that represents an invalid stream position. | |
600 | */ | |
385aec5a | 601 | virtual pos_type |
e1e0016d | 602 | seekoff(off_type, ios_base::seekdir, |
603 | ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) | |
385aec5a | 604 | { return pos_type(off_type(-1)); } |
e1e0016d | 605 | |
ce705c0a | 606 | /** |
607 | * @brief Alters the stream positions. | |
608 | * | |
609 | * Each derived class provides its own appropriate behavior. | |
610 | * @note Base class version does nothing, returns a @c pos_type | |
611 | * that represents an invalid stream position. | |
612 | */ | |
385aec5a | 613 | virtual pos_type |
614 | seekpos(pos_type, | |
e1e0016d | 615 | ios_base::openmode /*__mode*/ = ios_base::in | ios_base::out) |
385aec5a | 616 | { return pos_type(off_type(-1)); } |
e1e0016d | 617 | |
ce705c0a | 618 | /** |
619 | * @brief Synchronizes the buffer arrays with the controlled sequences. | |
620 | * @return -1 on failure. | |
621 | * | |
622 | * Each derived class provides its own appropriate behavior, | |
72117d76 | 623 | * including the definition of @a failure. |
ce705c0a | 624 | * @note Base class version does nothing, returns zero. |
625 | */ | |
385aec5a | 626 | virtual int |
e1e0016d | 627 | sync() { return 0; } |
628 | ||
ce705c0a | 629 | // [27.5.2.4.3] get area |
630 | /** | |
631 | * @brief Investigating the data available. | |
632 | * @return An estimate of the number of characters available in the | |
633 | * input sequence, or -1. | |
634 | * | |
72117d76 | 635 | * <em>If it returns a positive value, then successive calls to |
636 | * @c underflow() will not return @c traits::eof() until at | |
637 | * least that number of characters have been supplied. If @c | |
638 | * showmanyc() returns -1, then calls to @c underflow() or @c | |
639 | * uflow() will fail.</em> [27.5.2.4.3]/1 | |
ce705c0a | 640 | * |
641 | * @note Base class version does nothing, returns zero. | |
72117d76 | 642 | * @note The standard adds that <em>the intention is not only that the |
ce705c0a | 643 | * calls [to underflow or uflow] will not return @c eof() but |
72117d76 | 644 | * that they will return immediately.</em> |
645 | * @note The standard adds that <em>the morphemes of @c showmanyc are | |
646 | * @b es-how-many-see, not @b show-manic.</em> | |
ce705c0a | 647 | */ |
385aec5a | 648 | virtual streamsize |
e1e0016d | 649 | showmanyc() { return 0; } |
650 | ||
ce705c0a | 651 | /** |
652 | * @brief Multiple character extraction. | |
e12e4f3b | 653 | * @param __s A buffer area. |
654 | * @param __n Maximum number of characters to assign. | |
ce705c0a | 655 | * @return The number of characters assigned. |
656 | * | |
e12e4f3b | 657 | * Fills @a __s[0] through @a __s[__n-1] with characters from the input |
658 | * sequence, as if by @c sbumpc(). Stops when either @a __n characters | |
ce705c0a | 659 | * have been copied, or when @c traits::eof() would be copied. |
660 | * | |
661 | * It is expected that derived classes provide a more efficient | |
662 | * implementation by overriding this definition. | |
663 | */ | |
385aec5a | 664 | virtual streamsize |
e1e0016d | 665 | xsgetn(char_type* __s, streamsize __n); |
666 | ||
ce705c0a | 667 | /** |
668 | * @brief Fetches more data from the controlled sequence. | |
669 | * @return The first character from the <em>pending sequence</em>. | |
670 | * | |
671 | * Informally, this function is called when the input buffer is | |
672 | * exhausted (or does not exist, as buffering need not actually be | |
72117d76 | 673 | * done). If a buffer exists, it is @a refilled. In either case, the |
ce705c0a | 674 | * next available character is returned, or @c traits::eof() to |
675 | * indicate a null pending sequence. | |
676 | * | |
9fc1117c | 677 | * For a formal definition of the pending sequence, see a good text |
ce705c0a | 678 | * such as Langer & Kreft, or [27.5.2.4.3]/7-14. |
679 | * | |
680 | * A functioning input streambuf can be created by overriding only | |
681 | * this function (no buffer area will be used). For an example, see | |
0698cdf1 | 682 | * https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html |
ce705c0a | 683 | * |
684 | * @note Base class version does nothing, returns eof(). | |
685 | */ | |
385aec5a | 686 | virtual int_type |
e1e0016d | 687 | underflow() |
688 | { return traits_type::eof(); } | |
689 | ||
ce705c0a | 690 | /** |
691 | * @brief Fetches more data from the controlled sequence. | |
692 | * @return The first character from the <em>pending sequence</em>. | |
693 | * | |
694 | * Informally, this function does the same thing as @c underflow(), | |
695 | * and in fact is required to call that function. It also returns | |
696 | * the new character, like @c underflow() does. However, this | |
697 | * function also moves the read position forward by one. | |
698 | */ | |
385aec5a | 699 | virtual int_type |
700 | uflow() | |
e1e0016d | 701 | { |
702 | int_type __ret = traits_type::eof(); | |
385aec5a | 703 | const bool __testeof = traits_type::eq_int_type(this->underflow(), |
e99fa449 | 704 | __ret); |
87306449 | 705 | if (!__testeof) |
e1e0016d | 706 | { |
a6bfe6ae | 707 | __ret = traits_type::to_int_type(*this->gptr()); |
708 | this->gbump(1); | |
e1e0016d | 709 | } |
385aec5a | 710 | return __ret; |
e1e0016d | 711 | } |
712 | ||
ce705c0a | 713 | // [27.5.2.4.4] putback |
714 | /** | |
715 | * @brief Tries to back up the input sequence. | |
e12e4f3b | 716 | * @param __c The character to be inserted back into the sequence. |
72117d76 | 717 | * @return eof() on failure, <em>some other value</em> on success |
ce705c0a | 718 | * @post The constraints of @c gptr(), @c eback(), and @c pptr() |
719 | * are the same as for @c underflow(). | |
720 | * | |
721 | * @note Base class version does nothing, returns eof(). | |
722 | */ | |
385aec5a | 723 | virtual int_type |
e12e4f3b | 724 | pbackfail(int_type __c = traits_type::eof()) |
e1e0016d | 725 | { return traits_type::eof(); } |
726 | ||
727 | // Put area: | |
ce705c0a | 728 | /** |
729 | * @brief Multiple character insertion. | |
e12e4f3b | 730 | * @param __s A buffer area. |
731 | * @param __n Maximum number of characters to write. | |
ce705c0a | 732 | * @return The number of characters written. |
733 | * | |
e12e4f3b | 734 | * Writes @a __s[0] through @a __s[__n-1] to the output sequence, as if |
ce705c0a | 735 | * by @c sputc(). Stops when either @a n characters have been |
736 | * copied, or when @c sputc() would return @c traits::eof(). | |
737 | * | |
738 | * It is expected that derived classes provide a more efficient | |
739 | * implementation by overriding this definition. | |
740 | */ | |
385aec5a | 741 | virtual streamsize |
e1e0016d | 742 | xsputn(const char_type* __s, streamsize __n); |
743 | ||
ce705c0a | 744 | /** |
745 | * @brief Consumes data from the buffer; writes to the | |
746 | * controlled sequence. | |
e12e4f3b | 747 | * @param __c An additional character to consume. |
ce705c0a | 748 | * @return eof() to indicate failure, something else (usually |
e12e4f3b | 749 | * @a __c, or not_eof()) |
ce705c0a | 750 | * |
72117d76 | 751 | * Informally, this function is called when the output buffer |
752 | * is full (or does not exist, as buffering need not actually | |
753 | * be done). If a buffer exists, it is @a consumed, with | |
754 | * <em>some effect</em> on the controlled sequence. | |
755 | * (Typically, the buffer is written out to the sequence | |
756 | * verbatim.) In either case, the character @a c is also | |
e12e4f3b | 757 | * written out, if @a __c is not @c eof(). |
ce705c0a | 758 | * |
9fc1117c | 759 | * For a formal definition of this function, see a good text |
ce705c0a | 760 | * such as Langer & Kreft, or [27.5.2.4.5]/3-7. |
761 | * | |
762 | * A functioning output streambuf can be created by overriding only | |
763 | * this function (no buffer area will be used). | |
764 | * | |
765 | * @note Base class version does nothing, returns eof(). | |
766 | */ | |
385aec5a | 767 | virtual int_type |
e12e4f3b | 768 | overflow(int_type __c = traits_type::eof()) |
e1e0016d | 769 | { return traits_type::eof(); } |
770 | ||
f58707cd | 771 | #if _GLIBCXX_USE_DEPRECATED |
4d1232fa | 772 | // Annex D.6 |
e1e0016d | 773 | public: |
ce705c0a | 774 | /** |
775 | * @brief Tosses a character. | |
776 | * | |
777 | * Advances the read pointer, ignoring the character that would have | |
778 | * been read. | |
779 | * | |
780 | * See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html | |
99fb4782 | 781 | */ |
385aec5a | 782 | void |
783 | stossc() | |
e1e0016d | 784 | { |
385aec5a | 785 | if (this->gptr() < this->egptr()) |
a6bfe6ae | 786 | this->gbump(1); |
385aec5a | 787 | else |
e1e0016d | 788 | this->uflow(); |
789 | } | |
1d487aca | 790 | #endif |
e1e0016d | 791 | |
5affa0ef | 792 | // Also used by specializations for char and wchar_t in src. |
385aec5a | 793 | void |
5affa0ef | 794 | __safe_gbump(streamsize __n) { _M_in_cur += __n; } |
795 | ||
796 | void | |
797 | __safe_pbump(streamsize __n) { _M_out_cur += __n; } | |
798 | ||
385aec5a | 799 | #if __cplusplus < 201103L |
e1e0016d | 800 | private: |
385aec5a | 801 | #else |
802 | protected: | |
28f8cba2 | 803 | #endif |
804 | basic_streambuf(const basic_streambuf&); | |
385aec5a | 805 | |
806 | basic_streambuf& | |
28f8cba2 | 807 | operator=(const basic_streambuf&); |
385aec5a | 808 | |
28f8cba2 | 809 | #if __cplusplus >= 201103L |
385aec5a | 810 | void |
811 | swap(basic_streambuf& __sb) | |
812 | { | |
813 | std::swap(_M_in_beg, __sb._M_in_beg); | |
814 | std::swap(_M_in_cur, __sb._M_in_cur); | |
815 | std::swap(_M_in_end, __sb._M_in_end); | |
816 | std::swap(_M_out_beg, __sb._M_out_beg); | |
817 | std::swap(_M_out_cur, __sb._M_out_cur); | |
818 | std::swap(_M_out_end, __sb._M_out_end); | |
819 | std::swap(_M_buf_locale, __sb._M_buf_locale); | |
820 | } | |
821 | #endif | |
e1e0016d | 822 | }; |
6dd0a9c3 | 823 | |
28f8cba2 | 824 | #if __cplusplus >= 201103L |
825 | template<typename _CharT, typename _Traits> | |
826 | std::basic_streambuf<_CharT, _Traits>:: | |
827 | basic_streambuf(const basic_streambuf&) = default; | |
828 | ||
829 | template<typename _CharT, typename _Traits> | |
830 | std::basic_streambuf<_CharT, _Traits>& | |
831 | std::basic_streambuf<_CharT, _Traits>:: | |
832 | operator=(const basic_streambuf&) = default; | |
833 | #endif | |
834 | ||
6dd0a9c3 | 835 | // Explicit specialization declarations, defined in src/streambuf.cc. |
836 | template<> | |
837 | streamsize | |
c22bf199 | 838 | __copy_streambufs_eof(basic_streambuf<char>* __sbin, |
839 | basic_streambuf<char>* __sbout, bool& __ineof); | |
6dd0a9c3 | 840 | #ifdef _GLIBCXX_USE_WCHAR_T |
841 | template<> | |
842 | streamsize | |
c22bf199 | 843 | __copy_streambufs_eof(basic_streambuf<wchar_t>* __sbin, |
844 | basic_streambuf<wchar_t>* __sbout, bool& __ineof); | |
6dd0a9c3 | 845 | #endif |
1069247d | 846 | |
2948dd21 | 847 | _GLIBCXX_END_NAMESPACE_VERSION |
848 | } // namespace | |
e1e0016d | 849 | |
74642da2 | 850 | #include <bits/streambuf.tcc> |
e1e0016d | 851 | |
a438d9ac | 852 | #endif /* _GLIBCXX_STREAMBUF */ |