1// Output streams -*- C++ -*- 2 3// Copyright (C) 1997-2018 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 include/ostream 26 * This is a Standard C++ Library header. 27 */ 28 29// 30// ISO C++ 14882: 27.6.2 Output streams 31// 32 33#ifndef _GLIBCXX_OSTREAM 34#define _GLIBCXX_OSTREAM 1 35 36#pragma GCC system_header 37 38#include <ios> 39#include <bits/ostream_insert.h> 40 41namespace std _GLIBCXX_VISIBILITY(default) 42{ 43_GLIBCXX_BEGIN_NAMESPACE_VERSION 44 45 /** 46 * @brief Template class basic_ostream. 47 * @ingroup io 48 * 49 * @tparam _CharT Type of character stream. 50 * @tparam _Traits Traits for character type, defaults to 51 * char_traits<_CharT>. 52 * 53 * This is the base class for all output streams. It provides text 54 * formatting of all builtin types, and communicates with any class 55 * derived from basic_streambuf to do the actual output. 56 */ 57 template<typename _CharT, typename _Traits> 58 class basic_ostream : virtual public basic_ios<_CharT, _Traits> 59 { 60 public: 61 // Types (inherited from basic_ios): 62 typedef _CharT char_type; 63 typedef typename _Traits::int_type int_type; 64 typedef typename _Traits::pos_type pos_type; 65 typedef typename _Traits::off_type off_type; 66 typedef _Traits traits_type; 67 68 // Non-standard Types: 69 typedef basic_streambuf<_CharT, _Traits> __streambuf_type; 70 typedef basic_ios<_CharT, _Traits> __ios_type; 71 typedef basic_ostream<_CharT, _Traits> __ostream_type; 72 typedef num_put<_CharT, ostreambuf_iterator<_CharT, _Traits> > 73 __num_put_type; 74 typedef ctype<_CharT> __ctype_type; 75 76 /** 77 * @brief Base constructor. 78 * 79 * This ctor is almost never called by the user directly, rather from 80 * derived classes' initialization lists, which pass a pointer to 81 * their own stream buffer. 82 */ 83 explicit 84 basic_ostream(__streambuf_type* __sb) 85 { this->init(__sb); } 86 87 /** 88 * @brief Base destructor. 89 * 90 * This does very little apart from providing a virtual base dtor. 91 */ 92 virtual 93 ~basic_ostream() { } 94 95 /// Safe prefix/suffix operations. 96 class sentry; 97 friend class sentry; 98 99 //@{ 100 /** 101 * @brief Interface for manipulators. 102 * 103 * Manipulators such as @c std::endl and @c std::hex use these 104 * functions in constructs like "std::cout << std::endl". For more 105 * information, see the iomanip header. 106 */ 107 __ostream_type& 108 operator<<(__ostream_type& (*__pf)(__ostream_type&)) 109 { 110 // _GLIBCXX_RESOLVE_LIB_DEFECTS 111 // DR 60. What is a formatted input function? 112 // The inserters for manipulators are *not* formatted output functions. 113 return __pf(*this); 114 } 115 116 __ostream_type& 117 operator<<(__ios_type& (*__pf)(__ios_type&)) 118 { 119 // _GLIBCXX_RESOLVE_LIB_DEFECTS 120 // DR 60. What is a formatted input function? 121 // The inserters for manipulators are *not* formatted output functions. 122 __pf(*this); 123 return *this; 124 } 125 126 __ostream_type& 127 operator<<(ios_base& (*__pf) (ios_base&)) 128 { 129 // _GLIBCXX_RESOLVE_LIB_DEFECTS 130 // DR 60. What is a formatted input function? 131 // The inserters for manipulators are *not* formatted output functions. 132 __pf(*this); 133 return *this; 134 } 135 //@} 136 137 //@{ 138 /** 139 * @name Inserters 140 * 141 * All the @c operator<< functions (aka <em>formatted output 142 * functions</em>) have some common behavior. Each starts by 143 * constructing a temporary object of type std::basic_ostream::sentry. 144 * This can have several effects, concluding with the setting of a 145 * status flag; see the sentry documentation for more. 146 * 147 * If the sentry status is good, the function tries to generate 148 * whatever data is appropriate for the type of the argument. 149 * 150 * If an exception is thrown during insertion, ios_base::badbit 151 * will be turned on in the stream's error state without causing an 152 * ios_base::failure to be thrown. The original exception will then 153 * be rethrown. 154 */ 155 156 //@{ 157 /** 158 * @brief Integer arithmetic inserters 159 * @param __n A variable of builtin integral type. 160 * @return @c *this if successful 161 * 162 * These functions use the stream's current locale (specifically, the 163 * @c num_get facet) to perform numeric formatting. 164 */ 165 __ostream_type& 166 operator<<(long __n) 167 { return _M_insert(__n); } 168 169 __ostream_type& 170 operator<<(unsigned long __n) 171 { return _M_insert(__n); } 172 173 __ostream_type& 174 operator<<(bool __n) 175 { return _M_insert(__n); } 176 177 __ostream_type& 178 operator<<(short __n); 179 180 __ostream_type& 181 operator<<(unsigned short __n) 182 { 183 // _GLIBCXX_RESOLVE_LIB_DEFECTS 184 // 117. basic_ostream uses nonexistent num_put member functions. 185 return _M_insert(static_cast<unsigned long>(__n)); 186 } 187 188 __ostream_type& 189 operator<<(int __n); 190 191 __ostream_type& 192 operator<<(unsigned int __n) 193 { 194 // _GLIBCXX_RESOLVE_LIB_DEFECTS 195 // 117. basic_ostream uses nonexistent num_put member functions. 196 return _M_insert(static_cast<unsigned long>(__n)); 197 } 198 199#ifdef _GLIBCXX_USE_LONG_LONG 200 __ostream_type& 201 operator<<(long long __n) 202 { return _M_insert(__n); } 203 204 __ostream_type& 205 operator<<(unsigned long long __n) 206 { return _M_insert(__n); } 207#endif 208 //@} 209 210 //@{ 211 /** 212 * @brief Floating point arithmetic inserters 213 * @param __f A variable of builtin floating point type. 214 * @return @c *this if successful 215 * 216 * These functions use the stream's current locale (specifically, the 217 * @c num_get facet) to perform numeric formatting. 218 */ 219 __ostream_type& 220 operator<<(double __f) 221 { return _M_insert(__f); } 222 223 __ostream_type& 224 operator<<(float __f) 225 { 226 // _GLIBCXX_RESOLVE_LIB_DEFECTS 227 // 117. basic_ostream uses nonexistent num_put member functions. 228 return _M_insert(static_cast<double>(__f)); 229 } 230 231 __ostream_type& 232 operator<<(long double __f) 233 { return _M_insert(__f); } 234 //@} 235 236 /** 237 * @brief Pointer arithmetic inserters 238 * @param __p A variable of pointer type. 239 * @return @c *this if successful 240 * 241 * These functions use the stream's current locale (specifically, the 242 * @c num_get facet) to perform numeric formatting. 243 */ 244 __ostream_type& 245 operator<<(const void* __p) 246 { return _M_insert(__p); } 247 248 /** 249 * @brief Extracting from another streambuf. 250 * @param __sb A pointer to a streambuf 251 * 252 * This function behaves like one of the basic arithmetic extractors, 253 * in that it also constructs a sentry object and has the same error 254 * handling behavior. 255 * 256 * If @p __sb is NULL, the stream will set failbit in its error state. 257 * 258 * Characters are extracted from @p __sb and inserted into @c *this 259 * until one of the following occurs: 260 * 261 * - the input stream reaches end-of-file, 262 * - insertion into the output sequence fails (in this case, the 263 * character that would have been inserted is not extracted), or 264 * - an exception occurs while getting a character from @p __sb, which 265 * sets failbit in the error state 266 * 267 * If the function inserts no characters, failbit is set. 268 */ 269 __ostream_type& 270 operator<<(__streambuf_type* __sb); 271 //@} 272 273 //@{ 274 /** 275 * @name Unformatted Output Functions 276 * 277 * All the unformatted output functions have some common behavior. 278 * Each starts by constructing a temporary object of type 279 * std::basic_ostream::sentry. This has several effects, concluding 280 * with the setting of a status flag; see the sentry documentation 281 * for more. 282 * 283 * If the sentry status is good, the function tries to generate 284 * whatever data is appropriate for the type of the argument. 285 * 286 * If an exception is thrown during insertion, ios_base::badbit 287 * will be turned on in the stream's error state. If badbit is on in 288 * the stream's exceptions mask, the exception will be rethrown 289 * without completing its actions. 290 */ 291 292 /** 293 * @brief Simple insertion. 294 * @param __c The character to insert. 295 * @return *this 296 * 297 * Tries to insert @p __c. 298 * 299 * @note This function is not overloaded on signed char and 300 * unsigned char. 301 */ 302 __ostream_type& 303 put(char_type __c); 304 305 /** 306 * @brief Core write functionality, without sentry. 307 * @param __s The array to insert. 308 * @param __n Maximum number of characters to insert. 309 */ 310 void 311 _M_write(const char_type* __s, streamsize __n) 312 { 313 const streamsize __put = this->rdbuf()->sputn(__s, __n); 314 if (__put != __n) 315 this->setstate(ios_base::badbit); 316 } 317 318 /** 319 * @brief Character string insertion. 320 * @param __s The array to insert. 321 * @param __n Maximum number of characters to insert. 322 * @return *this 323 * 324 * Characters are copied from @p __s and inserted into the stream until 325 * one of the following happens: 326 * 327 * - @p __n characters are inserted 328 * - inserting into the output sequence fails (in this case, badbit 329 * will be set in the stream's error state) 330 * 331 * @note This function is not overloaded on signed char and 332 * unsigned char. 333 */ 334 __ostream_type& 335 write(const char_type* __s, streamsize __n); 336 //@} 337 338 /** 339 * @brief Synchronizing the stream buffer. 340 * @return *this 341 * 342 * If @c rdbuf() is a null pointer, changes nothing. 343 * 344 * Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1, 345 * sets badbit. 346 */ 347 __ostream_type& 348 flush(); 349 350 /** 351 * @brief Getting the current write position. 352 * @return A file position object. 353 * 354 * If @c fail() is not false, returns @c pos_type(-1) to indicate 355 * failure. Otherwise returns @c rdbuf()->pubseekoff(0,cur,out). 356 */ 357 pos_type 358 tellp(); 359 360 /** 361 * @brief Changing the current write position. 362 * @param __pos A file position object. 363 * @return *this 364 * 365 * If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos). If 366 * that function fails, sets failbit. 367 */ 368 __ostream_type& 369 seekp(pos_type); 370 371 /** 372 * @brief Changing the current write position. 373 * @param __off A file offset object. 374 * @param __dir The direction in which to seek. 375 * @return *this 376 * 377 * If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir). 378 * If that function fails, sets failbit. 379 */ 380 __ostream_type& 381 seekp(off_type, ios_base::seekdir); 382 383 protected: 384 basic_ostream() 385 { this->init(0); } 386 387#if __cplusplus >= 201103L 388 // Non-standard constructor that does not call init() 389 basic_ostream(basic_iostream<_CharT, _Traits>&) { } 390 391 basic_ostream(const basic_ostream&) = delete; 392 393 basic_ostream(basic_ostream&& __rhs) 394 : __ios_type() 395 { __ios_type::move(__rhs); } 396 397 // 27.7.3.3 Assign/swap 398 399 basic_ostream& operator=(const basic_ostream&) = delete; 400 401 basic_ostream& 402 operator=(basic_ostream&& __rhs) 403 { 404 swap(__rhs); 405 return *this; 406 } 407 408 void 409 swap(basic_ostream& __rhs) 410 { __ios_type::swap(__rhs); } 411#endif 412 413 template<typename _ValueT> 414 __ostream_type& 415 _M_insert(_ValueT __v); 416 }; 417 418 /** 419 * @brief Performs setup work for output streams. 420 * 421 * Objects of this class are created before all of the standard 422 * inserters are run. It is responsible for <em>exception-safe prefix and 423 * suffix operations</em>. 424 */ 425 template <typename _CharT, typename _Traits> 426 class basic_ostream<_CharT, _Traits>::sentry 427 { 428 // Data Members. 429 bool _M_ok; 430 basic_ostream<_CharT, _Traits>& _M_os; 431 432 public: 433 /** 434 * @brief The constructor performs preparatory work. 435 * @param __os The output stream to guard. 436 * 437 * If the stream state is good (@a __os.good() is true), then if the 438 * stream is tied to another output stream, @c is.tie()->flush() 439 * is called to synchronize the output sequences. 440 * 441 * If the stream state is still good, then the sentry state becomes 442 * true (@a okay). 443 */ 444 explicit 445 sentry(basic_ostream<_CharT, _Traits>& __os); 446 447 /** 448 * @brief Possibly flushes the stream. 449 * 450 * If @c ios_base::unitbuf is set in @c os.flags(), and 451 * @c std::uncaught_exception() is true, the sentry destructor calls 452 * @c flush() on the output stream. 453 */ 454 ~sentry() 455 { 456 // XXX MT 457 if (bool(_M_os.flags() & ios_base::unitbuf) && !uncaught_exception()) 458 { 459 // Can't call flush directly or else will get into recursive lock. 460 if (_M_os.rdbuf() && _M_os.rdbuf()->pubsync() == -1) 461 _M_os.setstate(ios_base::badbit); 462 } 463 } 464 465 /** 466 * @brief Quick status checking. 467 * @return The sentry state. 468 * 469 * For ease of use, sentries may be converted to booleans. The 470 * return value is that of the sentry state (true == okay). 471 */ 472#if __cplusplus >= 201103L 473 explicit 474#endif 475 operator bool() const 476 { return _M_ok; } 477 }; 478 479 //@{ 480 /** 481 * @brief Character inserters 482 * @param __out An output stream. 483 * @param __c A character. 484 * @return out 485 * 486 * Behaves like one of the formatted arithmetic inserters described in 487 * std::basic_ostream. After constructing a sentry object with good 488 * status, this function inserts a single character and any required 489 * padding (as determined by [22.2.2.2.2]). @c __out.width(0) is then 490 * called. 491 * 492 * If @p __c is of type @c char and the character type of the stream is not 493 * @c char, the character is widened before insertion. 494 */ 495 template<typename _CharT, typename _Traits> 496 inline basic_ostream<_CharT, _Traits>& 497 operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c) 498 { return __ostream_insert(__out, &__c, 1); } 499 500 template<typename _CharT, typename _Traits> 501 inline basic_ostream<_CharT, _Traits>& 502 operator<<(basic_ostream<_CharT, _Traits>& __out, char __c) 503 { return (__out << __out.widen(__c)); } 504 505 // Specialization 506 template <class _Traits> 507 inline basic_ostream<char, _Traits>& 508 operator<<(basic_ostream<char, _Traits>& __out, char __c) 509 { return __ostream_insert(__out, &__c, 1); } 510 511 // Signed and unsigned 512 template<class _Traits> 513 inline basic_ostream<char, _Traits>& 514 operator<<(basic_ostream<char, _Traits>& __out, signed char __c) 515 { return (__out << static_cast<char>(__c)); } 516 517 template<class _Traits> 518 inline basic_ostream<char, _Traits>& 519 operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c) 520 { return (__out << static_cast<char>(__c)); } 521 //@} 522 523 //@{ 524 /** 525 * @brief String inserters 526 * @param __out An output stream. 527 * @param __s A character string. 528 * @return out 529 * @pre @p __s must be a non-NULL pointer 530 * 531 * Behaves like one of the formatted arithmetic inserters described in 532 * std::basic_ostream. After constructing a sentry object with good 533 * status, this function inserts @c traits::length(__s) characters starting 534 * at @p __s, widened if necessary, followed by any required padding (as 535 * determined by [22.2.2.2.2]). @c __out.width(0) is then called. 536 */ 537 template<typename _CharT, typename _Traits> 538 inline basic_ostream<_CharT, _Traits>& 539 operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s) 540 { 541 if (!__s) 542 __out.setstate(ios_base::badbit); 543 else 544 __ostream_insert(__out, __s, 545 static_cast<streamsize>(_Traits::length(__s))); 546 return __out; 547 } 548 549 template<typename _CharT, typename _Traits> 550 basic_ostream<_CharT, _Traits> & 551 operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s); 552 553 // Partial specializations 554 template<class _Traits> 555 inline basic_ostream<char, _Traits>& 556 operator<<(basic_ostream<char, _Traits>& __out, const char* __s) 557 { 558 if (!__s) 559 __out.setstate(ios_base::badbit); 560 else 561 __ostream_insert(__out, __s, 562 static_cast<streamsize>(_Traits::length(__s))); 563 return __out; 564 } 565 566 // Signed and unsigned 567 template<class _Traits> 568 inline basic_ostream<char, _Traits>& 569 operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s) 570 { return (__out << reinterpret_cast<const char*>(__s)); } 571 572 template<class _Traits> 573 inline basic_ostream<char, _Traits> & 574 operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s) 575 { return (__out << reinterpret_cast<const char*>(__s)); } 576 //@} 577 578 // Standard basic_ostream manipulators 579 580 /** 581 * @brief Write a newline and flush the stream. 582 * 583 * This manipulator is often mistakenly used when a simple newline is 584 * desired, leading to poor buffering performance. See 585 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering 586 * for more on this subject. 587 */ 588 template<typename _CharT, typename _Traits> 589 inline basic_ostream<_CharT, _Traits>& 590 endl(basic_ostream<_CharT, _Traits>& __os) 591 { return flush(__os.put(__os.widen('\n'))); } 592 593 /** 594 * @brief Write a null character into the output sequence. 595 * 596 * <em>Null character</em> is @c CharT() by definition. For CharT 597 * of @c char, this correctly writes the ASCII @c NUL character 598 * string terminator. 599 */ 600 template<typename _CharT, typename _Traits> 601 inline basic_ostream<_CharT, _Traits>& 602 ends(basic_ostream<_CharT, _Traits>& __os) 603 { return __os.put(_CharT()); } 604 605 /** 606 * @brief Flushes the output stream. 607 * 608 * This manipulator simply calls the stream's @c flush() member function. 609 */ 610 template<typename _CharT, typename _Traits> 611 inline basic_ostream<_CharT, _Traits>& 612 flush(basic_ostream<_CharT, _Traits>& __os) 613 { return __os.flush(); } 614 615#if __cplusplus >= 201103L 616 template<typename _Ch, typename _Up> 617 basic_ostream<_Ch, _Up>& 618 __is_convertible_to_basic_ostream_test(basic_ostream<_Ch, _Up>*); 619 620 template<typename _Tp, typename = void> 621 struct __is_convertible_to_basic_ostream_impl 622 { 623 using __ostream_type = void; 624 }; 625 626 template<typename _Tp> 627 using __do_is_convertible_to_basic_ostream_impl = 628 decltype(__is_convertible_to_basic_ostream_test 629 (declval<typename remove_reference<_Tp>::type*>())); 630 631 template<typename _Tp> 632 struct __is_convertible_to_basic_ostream_impl 633 <_Tp, 634 __void_t<__do_is_convertible_to_basic_ostream_impl<_Tp>>> 635 { 636 using __ostream_type = 637 __do_is_convertible_to_basic_ostream_impl<_Tp>; 638 }; 639 640 template<typename _Tp> 641 struct __is_convertible_to_basic_ostream 642 : __is_convertible_to_basic_ostream_impl<_Tp> 643 { 644 public: 645 using type = __not_<is_void< 646 typename __is_convertible_to_basic_ostream_impl<_Tp>::__ostream_type>>; 647 constexpr static bool value = type::value; 648 }; 649 650 template<typename _Ostream, typename _Tp, typename = void> 651 struct __is_insertable : false_type {}; 652 653 template<typename _Ostream, typename _Tp> 654 struct __is_insertable<_Ostream, _Tp, 655 __void_t<decltype(declval<_Ostream&>() 656 << declval<const _Tp&>())>> 657 : true_type {}; 658 659 template<typename _Ostream> 660 using __rvalue_ostream_type = 661 typename __is_convertible_to_basic_ostream< 662 _Ostream>::__ostream_type; 663 664 /** 665 * @brief Generic inserter for rvalue stream 666 * @param __os An input stream. 667 * @param __x A reference to the object being inserted. 668 * @return os 669 * 670 * This is just a forwarding function to allow insertion to 671 * rvalue streams since they won't bind to the inserter functions 672 * that take an lvalue reference. 673 */ 674 template<typename _Ostream, typename _Tp> 675 inline 676 typename enable_if<__and_<__not_<is_lvalue_reference<_Ostream>>, 677 __is_convertible_to_basic_ostream<_Ostream>, 678 __is_insertable< 679 __rvalue_ostream_type<_Ostream>, 680 const _Tp&>>::value, 681 __rvalue_ostream_type<_Ostream>>::type 682 operator<<(_Ostream&& __os, const _Tp& __x) 683 { 684 __rvalue_ostream_type<_Ostream> __ret_os = __os; 685 __ret_os << __x; 686 return __ret_os; 687 } 688#endif // C++11 689 690_GLIBCXX_END_NAMESPACE_VERSION 691} // namespace std 692 693#include <bits/ostream.tcc> 694 695#endif /* _GLIBCXX_OSTREAM */ 696