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The C and C++ Include Header Files
/usr/include/c++/11/ostream
$ cat -n /usr/include/c++/11/ostream 1 // Output streams -*- C++ -*- 2 3 // Copyright (C) 1997-2021 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 41 namespace 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 #if __cplusplus >= 201703L 249 __ostream_type& 250 operator<<(nullptr_t) 251 { return *this << "nullptr"; } 252 #endif 253 254 #if __cplusplus > 202002L 255 __attribute__((__always_inline__)) 256 __ostream_type& 257 operator<<(const volatile void* __p) 258 { return _M_insert(const_cast<const void*>(__p)); } 259 #endif 260 261 /** 262 * @brief Extracting from another streambuf. 263 * @param __sb A pointer to a streambuf 264 * 265 * This function behaves like one of the basic arithmetic extractors, 266 * in that it also constructs a sentry object and has the same error 267 * handling behavior. 268 * 269 * If @p __sb is NULL, the stream will set failbit in its error state. 270 * 271 * Characters are extracted from @p __sb and inserted into @c *this 272 * until one of the following occurs: 273 * 274 * - the input stream reaches end-of-file, 275 * - insertion into the output sequence fails (in this case, the 276 * character that would have been inserted is not extracted), or 277 * - an exception occurs while getting a character from @p __sb, which 278 * sets failbit in the error state 279 * 280 * If the function inserts no characters, failbit is set. 281 */ 282 __ostream_type& 283 operator<<(__streambuf_type* __sb); 284 ///@} 285 286 ///@{ 287 /** 288 * @name Unformatted Output Functions 289 * 290 * All the unformatted output functions have some common behavior. 291 * Each starts by constructing a temporary object of type 292 * std::basic_ostream::sentry. This has several effects, concluding 293 * with the setting of a status flag; see the sentry documentation 294 * for more. 295 * 296 * If the sentry status is good, the function tries to generate 297 * whatever data is appropriate for the type of the argument. 298 * 299 * If an exception is thrown during insertion, ios_base::badbit 300 * will be turned on in the stream's error state. If badbit is on in 301 * the stream's exceptions mask, the exception will be rethrown 302 * without completing its actions. 303 */ 304 305 /** 306 * @brief Simple insertion. 307 * @param __c The character to insert. 308 * @return *this 309 * 310 * Tries to insert @p __c. 311 * 312 * @note This function is not overloaded on signed char and 313 * unsigned char. 314 */ 315 __ostream_type& 316 put(char_type __c); 317 318 /** 319 * @brief Core write functionality, without sentry. 320 * @param __s The array to insert. 321 * @param __n Maximum number of characters to insert. 322 */ 323 void 324 _M_write(const char_type* __s, streamsize __n) 325 { 326 const streamsize __put = this->rdbuf()->sputn(__s, __n); 327 if (__put != __n) 328 this->setstate(ios_base::badbit); 329 } 330 331 /** 332 * @brief Character string insertion. 333 * @param __s The array to insert. 334 * @param __n Maximum number of characters to insert. 335 * @return *this 336 * 337 * Characters are copied from @p __s and inserted into the stream until 338 * one of the following happens: 339 * 340 * - @p __n characters are inserted 341 * - inserting into the output sequence fails (in this case, badbit 342 * will be set in the stream's error state) 343 * 344 * @note This function is not overloaded on signed char and 345 * unsigned char. 346 */ 347 __ostream_type& 348 write(const char_type* __s, streamsize __n); 349 ///@} 350 351 /** 352 * @brief Synchronizing the stream buffer. 353 * @return *this 354 * 355 * If @c rdbuf() is a null pointer, changes nothing. 356 * 357 * Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1, 358 * sets badbit. 359 */ 360 __ostream_type& 361 flush(); 362 363 /** 364 * @brief Getting the current write position. 365 * @return A file position object. 366 * 367 * If @c fail() is not false, returns @c pos_type(-1) to indicate 368 * failure. Otherwise returns @c rdbuf()->pubseekoff(0,cur,out). 369 */ 370 pos_type 371 tellp(); 372 373 /** 374 * @brief Changing the current write position. 375 * @param __pos A file position object. 376 * @return *this 377 * 378 * If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos). If 379 * that function fails, sets failbit. 380 */ 381 __ostream_type& 382 seekp(pos_type); 383 384 /** 385 * @brief Changing the current write position. 386 * @param __off A file offset object. 387 * @param __dir The direction in which to seek. 388 * @return *this 389 * 390 * If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir). 391 * If that function fails, sets failbit. 392 */ 393 __ostream_type& 394 seekp(off_type, ios_base::seekdir); 395 396 protected: 397 basic_ostream() 398 { this->init(0); } 399 400 #if __cplusplus >= 201103L 401 // Non-standard constructor that does not call init() 402 basic_ostream(basic_iostream<_CharT, _Traits>&) { } 403 404 basic_ostream(const basic_ostream&) = delete; 405 406 basic_ostream(basic_ostream&& __rhs) 407 : __ios_type() 408 { __ios_type::move(__rhs); } 409 410 // 27.7.3.3 Assign/swap 411 412 basic_ostream& operator=(const basic_ostream&) = delete; 413 414 basic_ostream& 415 operator=(basic_ostream&& __rhs) 416 { 417 swap(__rhs); 418 return *this; 419 } 420 421 void 422 swap(basic_ostream& __rhs) 423 { __ios_type::swap(__rhs); } 424 #endif 425 426 template<typename _ValueT> 427 __ostream_type& 428 _M_insert(_ValueT __v); 429 }; 430 431 /** 432 * @brief Performs setup work for output streams. 433 * 434 * Objects of this class are created before all of the standard 435 * inserters are run. It is responsible for <em>exception-safe prefix and 436 * suffix operations</em>. 437 */ 438 template <typename _CharT, typename _Traits> 439 class basic_ostream<_CharT, _Traits>::sentry 440 { 441 // Data Members. 442 bool _M_ok; 443 basic_ostream<_CharT, _Traits>& _M_os; 444 445 public: 446 /** 447 * @brief The constructor performs preparatory work. 448 * @param __os The output stream to guard. 449 * 450 * If the stream state is good (@a __os.good() is true), then if the 451 * stream is tied to another output stream, @c is.tie()->flush() 452 * is called to synchronize the output sequences. 453 * 454 * If the stream state is still good, then the sentry state becomes 455 * true (@a okay). 456 */ 457 explicit 458 sentry(basic_ostream<_CharT, _Traits>& __os); 459 460 #pragma GCC diagnostic push 461 #pragma GCC diagnostic ignored "-Wdeprecated-declarations" 462 /** 463 * @brief Possibly flushes the stream. 464 * 465 * If @c ios_base::unitbuf is set in @c os.flags(), and 466 * @c std::uncaught_exception() is true, the sentry destructor calls 467 * @c flush() on the output stream. 468 */ 469 ~sentry() 470 { 471 // XXX MT 472 if (bool(_M_os.flags() & ios_base::unitbuf) && !uncaught_exception()) 473 { 474 // Can't call flush directly or else will get into recursive lock. 475 if (_M_os.rdbuf() && _M_os.rdbuf()->pubsync() == -1) 476 _M_os.setstate(ios_base::badbit); 477 } 478 } 479 #pragma GCC diagnostic pop 480 481 /** 482 * @brief Quick status checking. 483 * @return The sentry state. 484 * 485 * For ease of use, sentries may be converted to booleans. The 486 * return value is that of the sentry state (true == okay). 487 */ 488 #if __cplusplus >= 201103L 489 explicit 490 #endif 491 operator bool() const 492 { return _M_ok; } 493 }; 494 495 ///@{ 496 /** 497 * @brief Character inserters 498 * @param __out An output stream. 499 * @param __c A character. 500 * @return out 501 * 502 * Behaves like one of the formatted arithmetic inserters described in 503 * std::basic_ostream. After constructing a sentry object with good 504 * status, this function inserts a single character and any required 505 * padding (as determined by [22.2.2.2.2]). @c __out.width(0) is then 506 * called. 507 * 508 * If @p __c is of type @c char and the character type of the stream is not 509 * @c char, the character is widened before insertion. 510 */ 511 template<typename _CharT, typename _Traits> 512 inline basic_ostream<_CharT, _Traits>& 513 operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c) 514 { return __ostream_insert(__out, &__c, 1); } 515 516 template<typename _CharT, typename _Traits> 517 inline basic_ostream<_CharT, _Traits>& 518 operator<<(basic_ostream<_CharT, _Traits>& __out, char __c) 519 { return (__out << __out.widen(__c)); } 520 521 // Specialization 522 template<typename _Traits> 523 inline basic_ostream<char, _Traits>& 524 operator<<(basic_ostream<char, _Traits>& __out, char __c) 525 { return __ostream_insert(__out, &__c, 1); } 526 527 // Signed and unsigned 528 template<typename _Traits> 529 inline basic_ostream<char, _Traits>& 530 operator<<(basic_ostream<char, _Traits>& __out, signed char __c) 531 { return (__out << static_cast<char>(__c)); } 532 533 template<typename _Traits> 534 inline basic_ostream<char, _Traits>& 535 operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c) 536 { return (__out << static_cast<char>(__c)); } 537 538 #if __cplusplus > 201703L 539 // The following deleted overloads prevent formatting character values as 540 // numeric values. 541 542 template<typename _Traits> 543 basic_ostream<char, _Traits>& 544 operator<<(basic_ostream<char, _Traits>&, wchar_t) = delete; 545 546 #ifdef _GLIBCXX_USE_CHAR8_T 547 template<typename _Traits> 548 basic_ostream<char, _Traits>& 549 operator<<(basic_ostream<char, _Traits>&, char8_t) = delete; 550 #endif 551 552 template<typename _Traits> 553 basic_ostream<char, _Traits>& 554 operator<<(basic_ostream<char, _Traits>&, char16_t) = delete; 555 556 template<typename _Traits> 557 basic_ostream<char, _Traits>& 558 operator<<(basic_ostream<char, _Traits>&, char32_t) = delete; 559 560 #ifdef _GLIBCXX_USE_WCHAR_T 561 #ifdef _GLIBCXX_USE_CHAR8_T 562 template<typename _Traits> 563 basic_ostream<wchar_t, _Traits>& 564 operator<<(basic_ostream<wchar_t, _Traits>&, char8_t) = delete; 565 #endif // _GLIBCXX_USE_CHAR8_T 566 567 template<typename _Traits> 568 basic_ostream<wchar_t, _Traits>& 569 operator<<(basic_ostream<wchar_t, _Traits>&, char16_t) = delete; 570 571 template<typename _Traits> 572 basic_ostream<wchar_t, _Traits>& 573 operator<<(basic_ostream<wchar_t, _Traits>&, char32_t) = delete; 574 #endif // _GLIBCXX_USE_WCHAR_T 575 #endif // C++20 576 ///@} 577 578 ///@{ 579 /** 580 * @brief String inserters 581 * @param __out An output stream. 582 * @param __s A character string. 583 * @return out 584 * @pre @p __s must be a non-NULL pointer 585 * 586 * Behaves like one of the formatted arithmetic inserters described in 587 * std::basic_ostream. After constructing a sentry object with good 588 * status, this function inserts @c traits::length(__s) characters starting 589 * at @p __s, widened if necessary, followed by any required padding (as 590 * determined by [22.2.2.2.2]). @c __out.width(0) is then called. 591 */ 592 template<typename _CharT, typename _Traits> 593 inline basic_ostream<_CharT, _Traits>& 594 operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s) 595 { 596 if (!__s) 597 __out.setstate(ios_base::badbit); 598 else 599 __ostream_insert(__out, __s, 600 static_cast<streamsize>(_Traits::length(__s))); 601 return __out; 602 } 603 604 template<typename _CharT, typename _Traits> 605 basic_ostream<_CharT, _Traits> & 606 operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s); 607 608 // Partial specializations 609 template<typename _Traits> 610 inline basic_ostream<char, _Traits>& 611 operator<<(basic_ostream<char, _Traits>& __out, const char* __s) 612 { 613 if (!__s) 614 __out.setstate(ios_base::badbit); 615 else 616 __ostream_insert(__out, __s, 617 static_cast<streamsize>(_Traits::length(__s))); 618 return __out; 619 } 620 621 // Signed and unsigned 622 template<typename _Traits> 623 inline basic_ostream<char, _Traits>& 624 operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s) 625 { return (__out << reinterpret_cast<const char*>(__s)); } 626 627 template<typename _Traits> 628 inline basic_ostream<char, _Traits> & 629 operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s) 630 { return (__out << reinterpret_cast<const char*>(__s)); } 631 632 #if __cplusplus > 201703L 633 // The following deleted overloads prevent formatting strings as 634 // pointer values. 635 636 template<typename _Traits> 637 basic_ostream<char, _Traits>& 638 operator<<(basic_ostream<char, _Traits>&, const wchar_t*) = delete; 639 640 #ifdef _GLIBCXX_USE_CHAR8_T 641 template<typename _Traits> 642 basic_ostream<char, _Traits>& 643 operator<<(basic_ostream<char, _Traits>&, const char8_t*) = delete; 644 #endif // _GLIBCXX_USE_CHAR8_T 645 646 template<typename _Traits> 647 basic_ostream<char, _Traits>& 648 operator<<(basic_ostream<char, _Traits>&, const char16_t*) = delete; 649 650 template<typename _Traits> 651 basic_ostream<char, _Traits>& 652 operator<<(basic_ostream<char, _Traits>&, const char32_t*) = delete; 653 654 #ifdef _GLIBCXX_USE_WCHAR_T 655 #ifdef _GLIBCXX_USE_CHAR8_T 656 template<typename _Traits> 657 basic_ostream<wchar_t, _Traits>& 658 operator<<(basic_ostream<wchar_t, _Traits>&, const char8_t*) = delete; 659 #endif 660 661 template<typename _Traits> 662 basic_ostream<wchar_t, _Traits>& 663 operator<<(basic_ostream<wchar_t, _Traits>&, const char16_t*) = delete; 664 665 template<typename _Traits> 666 basic_ostream<wchar_t, _Traits>& 667 operator<<(basic_ostream<wchar_t, _Traits>&, const char32_t*) = delete; 668 #endif // _GLIBCXX_USE_WCHAR_T 669 #endif // C++20 670 ///@} 671 672 // Standard basic_ostream manipulators 673 674 /** 675 * @brief Write a newline and flush the stream. 676 * 677 * This manipulator is often mistakenly used when a simple newline is 678 * desired, leading to poor buffering performance. See 679 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering 680 * for more on this subject. 681 */ 682 template<typename _CharT, typename _Traits> 683 inline basic_ostream<_CharT, _Traits>& 684 endl(basic_ostream<_CharT, _Traits>& __os) 685 { return flush(__os.put(__os.widen('\n'))); } 686 687 /** 688 * @brief Write a null character into the output sequence. 689 * 690 * <em>Null character</em> is @c CharT() by definition. For CharT 691 * of @c char, this correctly writes the ASCII @c NUL character 692 * string terminator. 693 */ 694 template<typename _CharT, typename _Traits> 695 inline basic_ostream<_CharT, _Traits>& 696 ends(basic_ostream<_CharT, _Traits>& __os) 697 { return __os.put(_CharT()); } 698 699 /** 700 * @brief Flushes the output stream. 701 * 702 * This manipulator simply calls the stream's @c flush() member function. 703 */ 704 template<typename _CharT, typename _Traits> 705 inline basic_ostream<_CharT, _Traits>& 706 flush(basic_ostream<_CharT, _Traits>& __os) 707 { return __os.flush(); } 708 709 #if __cplusplus >= 201103L 710 // C++11 27.7.3.9 Rvalue stream insertion [ostream.rvalue] 711 // _GLIBCXX_RESOLVE_LIB_DEFECTS 712 // 1203. More useful rvalue stream insertion 713 714 #if __cpp_lib_concepts 715 // Use concepts if possible because they're cheaper to evaluate. 716 template<typename _Tp> 717 concept __derived_from_ios_base = is_class_v<_Tp> 718 && (!is_same_v<_Tp, ios_base>) 719 && requires (_Tp* __t, ios_base* __b) { __b = __t; }; 720 721 template<typename _Os, typename _Tp> 722 requires __derived_from_ios_base<_Os> 723 && requires (_Os& __os, const _Tp& __t) { __os << __t; } 724 using __rvalue_stream_insertion_t = _Os&&; 725 #else 726 template<typename _Tp> 727 using _Require_derived_from_ios_base 728 = _Require<is_class<_Tp>, __not_<is_same<_Tp, ios_base>>, 729 is_convertible<typename add_pointer<_Tp>::type, ios_base*>>; 730 731 template<typename _Os, typename _Tp, 732 typename = _Require_derived_from_ios_base<_Os>, 733 typename 734 = decltype(std::declval<_Os&>() << std::declval<const _Tp&>())> 735 using __rvalue_stream_insertion_t = _Os&&; 736 #endif 737 738 /** 739 * @brief Generic inserter for rvalue stream 740 * @param __os An input stream. 741 * @param __x A reference to the object being inserted. 742 * @return __os 743 * 744 * This is just a forwarding function to allow insertion to 745 * rvalue streams since they won't bind to the inserter functions 746 * that take an lvalue reference. 747 */ 748 template<typename _Ostream, typename _Tp> 749 inline __rvalue_stream_insertion_t<_Ostream, _Tp> 750 operator<<(_Ostream&& __os, const _Tp& __x) 751 { 752 __os << __x; 753 return std::move(__os); 754 } 755 756 #if __cplusplus > 201703L && _GLIBCXX_USE_CXX11_ABI 757 template<typename _CharT, typename _Traits> 758 class __syncbuf_base : public basic_streambuf<_CharT, _Traits> 759 { 760 public: 761 static bool* 762 _S_get(basic_streambuf<_CharT, _Traits>* __buf [[maybe_unused]]) noexcept 763 { 764 #if __cpp_rtti 765 if (auto __p = dynamic_cast<__syncbuf_base*>(__buf)) 766 return &__p->_M_emit_on_sync; 767 #endif 768 return nullptr; 769 } 770 771 protected: 772 __syncbuf_base(basic_streambuf<_CharT, _Traits>* __w = nullptr) 773 : _M_wrapped(__w) 774 { } 775 776 basic_streambuf<_CharT, _Traits>* _M_wrapped = nullptr; 777 bool _M_emit_on_sync = false; 778 bool _M_needs_sync = false; 779 }; 780 781 template<typename _CharT, typename _Traits> 782 inline basic_ostream<_CharT, _Traits>& 783 emit_on_flush(basic_ostream<_CharT, _Traits>& __os) 784 { 785 if (bool* __flag = __syncbuf_base<_CharT, _Traits>::_S_get(__os.rdbuf())) 786 *__flag = true; 787 return __os; 788 } 789 790 template<typename _CharT, typename _Traits> 791 inline basic_ostream<_CharT, _Traits>& 792 noemit_on_flush(basic_ostream<_CharT, _Traits>& __os) 793 { 794 if (bool* __flag = __syncbuf_base<_CharT, _Traits>::_S_get(__os.rdbuf())) 795 *__flag = false; 796 return __os; 797 } 798 799 template<typename _CharT, typename _Traits> 800 inline basic_ostream<_CharT, _Traits>& 801 flush_emit(basic_ostream<_CharT, _Traits>& __os) 802 { 803 struct _Restore 804 { 805 ~_Restore() { *_M_flag = _M_prev; } 806 807 bool _M_prev = false; 808 bool* _M_flag = &_M_prev; 809 } __restore; 810 811 if (bool* __flag = __syncbuf_base<_CharT, _Traits>::_S_get(__os.rdbuf())) 812 { 813 __restore._M_prev = *__flag; 814 __restore._M_flag = __flag; 815 *__flag = true; 816 } 817 818 __os.flush(); 819 return __os; 820 } 821 822 #endif // C++20 823 824 #endif // C++11 825 826 _GLIBCXX_END_NAMESPACE_VERSION 827 } // namespace std 828 829 #include <bits/ostream.tcc> 830 831 #endif /* _GLIBCXX_OSTREAM */
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