libstdc++-v3/include/std/ostream

   1 // Output streams -*- C++ -*-
   2
   3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   4 // 2006, 2007, 2008, 2009, 2010, 2011, 2012
   5 // Free Software Foundation, Inc.
   6 //
   7 // This file is part of the GNU ISO C++ Library.  This library is free
   8 // software; you can redistribute it and/or modify it under the
   9 // terms of the GNU General Public License as published by the
  10 // Free Software Foundation; either version 3, or (at your option)
  11 // any later version.
  12
  13 // This library is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // Under Section 7 of GPL version 3, you are granted additional
  19 // permissions described in the GCC Runtime Library Exception, version
  20 // 3.1, as published by the Free Software Foundation.
  21
  22 // You should have received a copy of the GNU General Public License and
  23 // a copy of the GCC Runtime Library Exception along with this program;
  24 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25 // <http://www.gnu.org/licenses/>.
  26
  27 /** @file include/ostream
  28  *  This is a Standard C++ Library header.
  29  */
  30
  31 //
  32 // ISO C++ 14882: 27.6.2  Output streams
  33 //
  34
  35 #ifndef _GLIBCXX_OSTREAM
  36 #define _GLIBCXX_OSTREAM 1
  37
  38 #pragma GCC system_header
  39
  40 #include <ios>
  41 #include <bits/ostream_insert.h>
  42
  43 namespace std _GLIBCXX_VISIBILITY(default)
  44 {
  45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  46
  47   /**
  48    *  @brief  Template class basic_ostream.
  49    *  @ingroup io
  50    *
  51    *  @tparam _CharT  Type of character stream.
  52    *  @tparam _Traits  Traits for character type, defaults to
  53    *                   char_traits<_CharT>.
  54    *
  55    *  This is the base class for all output streams.  It provides text
  56    *  formatting of all builtin types, and communicates with any class
  57    *  derived from basic_streambuf to do the actual output.
  58   */
  59   template<typename _CharT, typename _Traits>
  60     class basic_ostream : virtual public basic_ios<_CharT, _Traits>
  61     {
  62     public:
  63       // Types (inherited from basic_ios):
  64       typedef _CharT                                    char_type;
  65       typedef typename _Traits::int_type                int_type;
  66       typedef typename _Traits::pos_type                pos_type;
  67       typedef typename _Traits::off_type                off_type;
  68       typedef _Traits                                   traits_type;
  69
  70       // Non-standard Types:
  71       typedef basic_streambuf<_CharT, _Traits>          __streambuf_type;
  72       typedef basic_ios<_CharT, _Traits>                __ios_type;
  73       typedef basic_ostream<_CharT, _Traits>            __ostream_type;
  74       typedef num_put<_CharT, ostreambuf_iterator<_CharT, _Traits> >
  75                                                         __num_put_type;
  76       typedef ctype<_CharT>                             __ctype_type;
  77
  78       /**
  79        *  @brief  Base constructor.
  80        *
  81        *  This ctor is almost never called by the user directly, rather from
  82        *  derived classes' initialization lists, which pass a pointer to
  83        *  their own stream buffer.
  84       */
  85       explicit
  86       basic_ostream(__streambuf_type* __sb)
  87       { this->init(__sb); }
  88
  89       /**
  90        *  @brief  Base destructor.
  91        *
  92        *  This does very little apart from providing a virtual base dtor.
  93       */
  94       virtual
  95       ~basic_ostream() { }
  96
  97       /// Safe prefix/suffix operations.
  98       class sentry;
  99       friend class sentry;
 100
 101       //@{
 102       /**
 103        *  @brief  Interface for manipulators.
 104        *
 105        *  Manipulators such as @c std::endl and @c std::hex use these
 106        *  functions in constructs like "std::cout << std::endl".  For more
 107        *  information, see the iomanip header.
 108       */
 109       __ostream_type&
 110       operator<<(__ostream_type& (*__pf)(__ostream_type&))
 111       {
 112         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 113         // DR 60. What is a formatted input function?
 114         // The inserters for manipulators are *not* formatted output functions.
 115         return __pf(*this);
 116       }
 117
 118       __ostream_type&
 119       operator<<(__ios_type& (*__pf)(__ios_type&))
 120       {
 121         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 122         // DR 60. What is a formatted input function?
 123         // The inserters for manipulators are *not* formatted output functions.
 124         __pf(*this);
 125         return *this;
 126       }
 127
 128       __ostream_type&
 129       operator<<(ios_base& (*__pf) (ios_base&))
 130       {
 131         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 132         // DR 60. What is a formatted input function?
 133         // The inserters for manipulators are *not* formatted output functions.
 134         __pf(*this);
 135         return *this;
 136       }
 137       //@}
 138
 139       //@{
 140       /**
 141        *  @name Inserters
 142        *
 143        *  All the @c operator<< functions (aka <em>formatted output
 144        *  functions</em>) have some common behavior.  Each starts by
 145        *  constructing a temporary object of type std::basic_ostream::sentry.
 146        *  This can have several effects, concluding with the setting of a
 147        *  status flag; see the sentry documentation for more.
 148        *
 149        *  If the sentry status is good, the function tries to generate
 150        *  whatever data is appropriate for the type of the argument.
 151        *
 152        *  If an exception is thrown during insertion, ios_base::badbit
 153        *  will be turned on in the stream's error state without causing an
 154        *  ios_base::failure to be thrown.  The original exception will then
 155        *  be rethrown.
 156       */
 157
 158       //@{
 159       /**
 160        *  @brief Integer arithmetic inserters
 161        *  @param  __n A variable of builtin integral type.
 162        *  @return  @c *this if successful
 163        *
 164        *  These functions use the stream's current locale (specifically, the
 165        *  @c num_get facet) to perform numeric formatting.
 166       */
 167       __ostream_type&
 168       operator<<(long __n)
 169       { return _M_insert(__n); }
 170
 171       __ostream_type&
 172       operator<<(unsigned long __n)
 173       { return _M_insert(__n); }
 174
 175       __ostream_type&
 176       operator<<(bool __n)
 177       { return _M_insert(__n); }
 178
 179       __ostream_type&
 180       operator<<(short __n);
 181
 182       __ostream_type&
 183       operator<<(unsigned short __n)
 184       {
 185         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 186         // 117. basic_ostream uses nonexistent num_put member functions.
 187         return _M_insert(static_cast<unsigned long>(__n));
 188       }
 189
 190       __ostream_type&
 191       operator<<(int __n);
 192
 193       __ostream_type&
 194       operator<<(unsigned int __n)
 195       {
 196         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 197         // 117. basic_ostream uses nonexistent num_put member functions.
 198         return _M_insert(static_cast<unsigned long>(__n));
 199       }
 200
 201 #ifdef _GLIBCXX_USE_LONG_LONG
 202       __ostream_type&
 203       operator<<(long long __n)
 204       { return _M_insert(__n); }
 205
 206       __ostream_type&
 207       operator<<(unsigned long long __n)
 208       { return _M_insert(__n); }
 209 #endif
 210       //@}
 211
 212       //@{
 213       /**
 214        *  @brief  Floating point arithmetic inserters
 215        *  @param  __f A variable of builtin floating point type.
 216        *  @return  @c *this if successful
 217        *
 218        *  These functions use the stream's current locale (specifically, the
 219        *  @c num_get facet) to perform numeric formatting.
 220       */
 221       __ostream_type&
 222       operator<<(double __f)
 223       { return _M_insert(__f); }
 224
 225       __ostream_type&
 226       operator<<(float __f)
 227       {
 228         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 229         // 117. basic_ostream uses nonexistent num_put member functions.
 230         return _M_insert(static_cast<double>(__f));
 231       }
 232
 233       __ostream_type&
 234       operator<<(long double __f)
 235       { return _M_insert(__f); }
 236       //@}
 237
 238       /**
 239        *  @brief  Pointer arithmetic inserters
 240        *  @param  __p A variable of pointer type.
 241        *  @return  @c *this if successful
 242        *
 243        *  These functions use the stream's current locale (specifically, the
 244        *  @c num_get facet) to perform numeric formatting.
 245       */
 246       __ostream_type&
 247       operator<<(const void* __p)
 248       { return _M_insert(__p); }
 249
 250       /**
 251        *  @brief  Extracting from another streambuf.
 252        *  @param  __sb  A pointer to a streambuf
 253        *
 254        *  This function behaves like one of the basic arithmetic extractors,
 255        *  in that it also constructs a sentry object and has the same error
 256        *  handling behavior.
 257        *
 258        *  If @p __sb is NULL, the stream will set failbit in its error state.
 259        *
 260        *  Characters are extracted from @p __sb and inserted into @c *this
 261        *  until one of the following occurs:
 262        *
 263        *  - the input stream reaches end-of-file,
 264        *  - insertion into the output sequence fails (in this case, the
 265        *    character that would have been inserted is not extracted), or
 266        *  - an exception occurs while getting a character from @p __sb, which
 267        *    sets failbit in the error state
 268        *
 269        *  If the function inserts no characters, failbit is set.
 270       */
 271       __ostream_type&
 272       operator<<(__streambuf_type* __sb);
 273       //@}
 274
 275       //@{
 276       /**
 277        *  @name Unformatted Output Functions
 278        *
 279        *  All the unformatted output functions have some common behavior.
 280        *  Each starts by constructing a temporary object of type
 281        *  std::basic_ostream::sentry.  This has several effects, concluding
 282        *  with the setting of a status flag; see the sentry documentation
 283        *  for more.
 284        *
 285        *  If the sentry status is good, the function tries to generate
 286        *  whatever data is appropriate for the type of the argument.
 287        *
 288        *  If an exception is thrown during insertion, ios_base::badbit
 289        *  will be turned on in the stream's error state.  If badbit is on in
 290        *  the stream's exceptions mask, the exception will be rethrown
 291        *  without completing its actions.
 292       */
 293
 294       /**
 295        *  @brief  Simple insertion.
 296        *  @param  __c  The character to insert.
 297        *  @return  *this
 298        *
 299        *  Tries to insert @p __c.
 300        *
 301        *  @note  This function is not overloaded on signed char and
 302        *         unsigned char.
 303       */
 304       __ostream_type&
 305       put(char_type __c);
 306
 307       /**
 308        *  @brief  Core write functionality, without sentry.
 309        *  @param  __s  The array to insert.
 310        *  @param  __n  Maximum number of characters to insert.
 311       */
 312       void
 313       _M_write(const char_type* __s, streamsize __n)
 314       {
 315         const streamsize __put = this->rdbuf()->sputn(__s, __n);
 316         if (__put != __n)
 317           this->setstate(ios_base::badbit);
 318       }
 319
 320       /**
 321        *  @brief  Character string insertion.
 322        *  @param  __s  The array to insert.
 323        *  @param  __n  Maximum number of characters to insert.
 324        *  @return  *this
 325        *
 326        *  Characters are copied from @p __s and inserted into the stream until
 327        *  one of the following happens:
 328        *
 329        *  - @p __n characters are inserted
 330        *  - inserting into the output sequence fails (in this case, badbit
 331        *    will be set in the stream's error state)
 332        *
 333        *  @note  This function is not overloaded on signed char and
 334        *         unsigned char.
 335       */
 336       __ostream_type&
 337       write(const char_type* __s, streamsize __n);
 338       //@}
 339
 340       /**
 341        *  @brief  Synchronizing the stream buffer.
 342        *  @return  *this
 343        *
 344        *  If @c rdbuf() is a null pointer, changes nothing.
 345        *
 346        *  Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
 347        *  sets badbit.
 348       */
 349       __ostream_type&
 350       flush();
 351
 352       /**
 353        *  @brief  Getting the current write position.
 354        *  @return  A file position object.
 355        *
 356        *  If @c fail() is not false, returns @c pos_type(-1) to indicate
 357        *  failure.  Otherwise returns @c rdbuf()->pubseekoff(0,cur,out).
 358       */
 359       pos_type
 360       tellp();
 361
 362       /**
 363        *  @brief  Changing the current write position.
 364        *  @param  __pos  A file position object.
 365        *  @return  *this
 366        *
 367        *  If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos).  If
 368        *  that function fails, sets failbit.
 369       */
 370       __ostream_type&
 371       seekp(pos_type);
 372
 373       /**
 374        *  @brief  Changing the current write position.
 375        *  @param  __off  A file offset object.
 376        *  @param  __dir  The direction in which to seek.
 377        *  @return  *this
 378        *
 379        *  If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir).
 380        *  If that function fails, sets failbit.
 381       */
 382        __ostream_type&
 383       seekp(off_type, ios_base::seekdir);
 384
 385     protected:
 386       basic_ostream()
 387       { this->init(0); }
 388
 389       template<typename _ValueT>
 390         __ostream_type&
 391         _M_insert(_ValueT __v);
 392     };
 393
 394   /**
 395    *  @brief  Performs setup work for output streams.
 396    *
 397    *  Objects of this class are created before all of the standard
 398    *  inserters are run.  It is responsible for <em>exception-safe prefix and
 399    *  suffix operations</em>.
 400   */
 401   template <typename _CharT, typename _Traits>
 402     class basic_ostream<_CharT, _Traits>::sentry
 403     {
 404       // Data Members.
 405       bool                              _M_ok;
 406       basic_ostream<_CharT, _Traits>&   _M_os;
 407
 408     public:
 409       /**
 410        *  @brief  The constructor performs preparatory work.
 411        *  @param  __os  The output stream to guard.
 412        *
 413        *  If the stream state is good (@a __os.good() is true), then if the
 414        *  stream is tied to another output stream, @c is.tie()->flush()
 415        *  is called to synchronize the output sequences.
 416        *
 417        *  If the stream state is still good, then the sentry state becomes
 418        *  true (@a okay).
 419       */
 420       explicit
 421       sentry(basic_ostream<_CharT, _Traits>& __os);
 422
 423       /**
 424        *  @brief  Possibly flushes the stream.
 425        *
 426        *  If @c ios_base::unitbuf is set in @c os.flags(), and
 427        *  @c std::uncaught_exception() is true, the sentry destructor calls
 428        *  @c flush() on the output stream.
 429       */
 430       ~sentry()
 431       {
 432         // XXX MT
 433         if (bool(_M_os.flags() & ios_base::unitbuf) && !uncaught_exception())
 434           {
 435             // Can't call flush directly or else will get into recursive lock.
 436             if (_M_os.rdbuf() && _M_os.rdbuf()->pubsync() == -1)
 437               _M_os.setstate(ios_base::badbit);
 438           }
 439       }
 440
 441       /**
 442        *  @brief  Quick status checking.
 443        *  @return  The sentry state.
 444        *
 445        *  For ease of use, sentries may be converted to booleans.  The
 446        *  return value is that of the sentry state (true == okay).
 447       */
 448 #if __cplusplus >= 201103L
 449       explicit
 450 #endif
 451       operator bool() const
 452       { return _M_ok; }
 453     };
 454
 455   //@{
 456   /**
 457    *  @brief  Character inserters
 458    *  @param  __out  An output stream.
 459    *  @param  __c  A character.
 460    *  @return  out
 461    *
 462    *  Behaves like one of the formatted arithmetic inserters described in
 463    *  std::basic_ostream.  After constructing a sentry object with good
 464    *  status, this function inserts a single character and any required
 465    *  padding (as determined by [22.2.2.2.2]).  @c __out.width(0) is then
 466    *  called.
 467    *
 468    *  If @p __c is of type @c char and the character type of the stream is not
 469    *  @c char, the character is widened before insertion.
 470   */
 471   template<typename _CharT, typename _Traits>
 472     inline basic_ostream<_CharT, _Traits>&
 473     operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c)
 474     { return __ostream_insert(__out, &__c, 1); }
 475
 476   template<typename _CharT, typename _Traits>
 477     inline basic_ostream<_CharT, _Traits>&
 478     operator<<(basic_ostream<_CharT, _Traits>& __out, char __c)
 479     { return (__out << __out.widen(__c)); }
 480
 481   // Specialization
 482   template <class _Traits>
 483     inline basic_ostream<char, _Traits>&
 484     operator<<(basic_ostream<char, _Traits>& __out, char __c)
 485     { return __ostream_insert(__out, &__c, 1); }
 486
 487   // Signed and unsigned
 488   template<class _Traits>
 489     inline basic_ostream<char, _Traits>&
 490     operator<<(basic_ostream<char, _Traits>& __out, signed char __c)
 491     { return (__out << static_cast<char>(__c)); }
 492
 493   template<class _Traits>
 494     inline basic_ostream<char, _Traits>&
 495     operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c)
 496     { return (__out << static_cast<char>(__c)); }
 497   //@}
 498
 499   //@{
 500   /**
 501    *  @brief  String inserters
 502    *  @param  __out  An output stream.
 503    *  @param  __s  A character string.
 504    *  @return  out
 505    *  @pre  @p __s must be a non-NULL pointer
 506    *
 507    *  Behaves like one of the formatted arithmetic inserters described in
 508    *  std::basic_ostream.  After constructing a sentry object with good
 509    *  status, this function inserts @c traits::length(__s) characters starting
 510    *  at @p __s, widened if necessary, followed by any required padding (as
 511    *  determined by [22.2.2.2.2]).  @c __out.width(0) is then called.
 512   */
 513   template<typename _CharT, typename _Traits>
 514     inline basic_ostream<_CharT, _Traits>&
 515     operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s)
 516     {
 517       if (!__s)
 518         __out.setstate(ios_base::badbit);
 519       else
 520         __ostream_insert(__out, __s,
 521                          static_cast<streamsize>(_Traits::length(__s)));
 522       return __out;
 523     }
 524
 525   template<typename _CharT, typename _Traits>
 526     basic_ostream<_CharT, _Traits> &
 527     operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s);
 528
 529   // Partial specializations
 530   template<class _Traits>
 531     inline basic_ostream<char, _Traits>&
 532     operator<<(basic_ostream<char, _Traits>& __out, const char* __s)
 533     {
 534       if (!__s)
 535         __out.setstate(ios_base::badbit);
 536       else
 537         __ostream_insert(__out, __s,
 538                          static_cast<streamsize>(_Traits::length(__s)));
 539       return __out;
 540     }
 541
 542   // Signed and unsigned
 543   template<class _Traits>
 544     inline basic_ostream<char, _Traits>&
 545     operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s)
 546     { return (__out << reinterpret_cast<const char*>(__s)); }
 547
 548   template<class _Traits>
 549     inline basic_ostream<char, _Traits> &
 550     operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s)
 551     { return (__out << reinterpret_cast<const char*>(__s)); }
 552   //@}
 553
 554   // Standard basic_ostream manipulators
 555
 556   /**
 557    *  @brief  Write a newline and flush the stream.
 558    *
 559    *  This manipulator is often mistakenly used when a simple newline is
 560    *  desired, leading to poor buffering performance.  See
 561    *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html
 562    *  for more on this subject.
 563   */
 564   template<typename _CharT, typename _Traits>
 565     inline basic_ostream<_CharT, _Traits>&
 566     endl(basic_ostream<_CharT, _Traits>& __os)
 567     { return flush(__os.put(__os.widen('\n'))); }
 568
 569   /**
 570    *  @brief  Write a null character into the output sequence.
 571    *
 572    *  <em>Null character</em> is @c CharT() by definition.  For CharT
 573    *  of @c char, this correctly writes the ASCII @c NUL character
 574    *  string terminator.
 575   */
 576   template<typename _CharT, typename _Traits>
 577     inline basic_ostream<_CharT, _Traits>&
 578     ends(basic_ostream<_CharT, _Traits>& __os)
 579     { return __os.put(_CharT()); }
 580
 581   /**
 582    *  @brief  Flushes the output stream.
 583    *
 584    *  This manipulator simply calls the stream's @c flush() member function.
 585   */
 586   template<typename _CharT, typename _Traits>
 587     inline basic_ostream<_CharT, _Traits>&
 588     flush(basic_ostream<_CharT, _Traits>& __os)
 589     { return __os.flush(); }
 590
 591 #if __cplusplus >= 201103L
 592   /**
 593    *  @brief  Generic inserter for rvalue stream
 594    *  @param  __os  An input stream.
 595    *  @param  __x  A reference to the object being inserted.
 596    *  @return  os
 597    *
 598    *  This is just a forwarding function to allow insertion to
 599    *  rvalue streams since they won't bind to the inserter functions
 600    *  that take an lvalue reference.
 601   */
 602   template<typename _CharT, typename _Traits, typename _Tp>
 603     inline basic_ostream<_CharT, _Traits>&
 604     operator<<(basic_ostream<_CharT, _Traits>&& __os, const _Tp& __x)
 605     { return (__os << __x); }
 606 #endif // C++11
 607
 608 _GLIBCXX_END_NAMESPACE_VERSION
 609 } // namespace std
 610
 611 #include <bits/ostream.tcc>
 612
 613 #endif  /* _GLIBCXX_OSTREAM */