libstdc++-v3/include/std/std_ostream.h

   1 // Output streams -*- C++ -*-
   2
   3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   4 // 2006, 2007
   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 2, 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 // You should have received a copy of the GNU General Public License along
  19 // with this library; see the file COPYING.  If not, write to the Free
  20 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  21 // USA.
  22
  23 // As a special exception, you may use this file as part of a free software
  24 // library without restriction.  Specifically, if other files instantiate
  25 // templates or use macros or inline functions from this file, or you compile
  26 // this file and link it with other files to produce an executable, this
  27 // file does not by itself cause the resulting executable to be covered by
  28 // the GNU General Public License.  This exception does not however
  29 // invalidate any other reasons why the executable file might be covered by
  30 // the GNU General Public License.
  31
  32 /** @file ostream
  33  *  This is a Standard C++ Library header.
  34  */
  35
  36 //
  37 // ISO C++ 14882: 27.6.2  Output streams
  38 //
  39
  40 #ifndef _GLIBCXX_OSTREAM
  41 #define _GLIBCXX_OSTREAM 1
  42
  43 #pragma GCC system_header
  44
  45 #include <ios>
  46 #include <bits/ostream_insert.h>
  47
  48 _GLIBCXX_BEGIN_NAMESPACE(std)
  49
  50   // [27.6.2.1] Template class basic_ostream
  51   /**
  52    *  @brief  Controlling output.
  53    *
  54    *  This is the base class for all output streams.  It provides text
  55    *  formatting of all builtin types, and communicates with any class
  56    *  derived from basic_streambuf to do the actual output.
  57   */
  58   template<typename _CharT, typename _Traits>
  59     class basic_ostream : virtual public basic_ios<_CharT, _Traits>
  60     {
  61     public:
  62       // Types (inherited from basic_ios (27.4.4)):
  63       typedef _CharT                                    char_type;
  64       typedef typename _Traits::int_type                int_type;
  65       typedef typename _Traits::pos_type                pos_type;
  66       typedef typename _Traits::off_type                off_type;
  67       typedef _Traits                                   traits_type;
  68
  69       // Non-standard Types:
  70       typedef basic_streambuf<_CharT, _Traits>          __streambuf_type;
  71       typedef basic_ios<_CharT, _Traits>                __ios_type;
  72       typedef basic_ostream<_CharT, _Traits>            __ostream_type;
  73       typedef num_put<_CharT, ostreambuf_iterator<_CharT, _Traits> >
  74                                                         __num_put_type;
  75       typedef ctype<_CharT>                             __ctype_type;
  76
  77       // [27.6.2.2] constructor/destructor
  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       // [27.6.2.3] prefix/suffix
  98       class sentry;
  99       friend class sentry;
 100
 101       // [27.6.2.5] formatted output
 102       // [27.6.2.5.3]  basic_ostream::operator<<
 103       //@{
 104       /**
 105        *  @brief  Interface for manipulators.
 106        *
 107        *  Manuipulators such as @c std::endl and @c std::hex use these
 108        *  functions in constructs like "std::cout << std::endl".  For more
 109        *  information, see the iomanip header.
 110       */
 111       __ostream_type&
 112       operator<<(__ostream_type& (*__pf)(__ostream_type&))
 113       {
 114         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 115         // DR 60. What is a formatted input function?
 116         // The inserters for manipulators are *not* formatted output functions.
 117         return __pf(*this);
 118       }
 119
 120       __ostream_type&
 121       operator<<(__ios_type& (*__pf)(__ios_type&))
 122       {
 123         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 124         // DR 60. What is a formatted input function?
 125         // The inserters for manipulators are *not* formatted output functions.
 126         __pf(*this);
 127         return *this;
 128       }
 129
 130       __ostream_type&
 131       operator<<(ios_base& (*__pf) (ios_base&))
 132       {
 133         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 134         // DR 60. What is a formatted input function?
 135         // The inserters for manipulators are *not* formatted output functions.
 136         __pf(*this);
 137         return *this;
 138       }
 139       //@}
 140
 141       // [27.6.2.5.2] arithmetic inserters
 142       /**
 143        *  @name Arithmetic Inserters
 144        *
 145        *  All the @c operator<< functions (aka <em>formatted output
 146        *  functions</em>) have some common behavior.  Each starts by
 147        *  constructing a temporary object of type std::basic_ostream::sentry.
 148        *  This can have several effects, concluding with the setting of a
 149        *  status flag; see the sentry documentation for more.
 150        *
 151        *  If the sentry status is good, the function tries to generate
 152        *  whatever data is appropriate for the type of the argument.
 153        *
 154        *  If an exception is thrown during insertion, ios_base::badbit
 155        *  will be turned on in the stream's error state without causing an
 156        *  ios_base::failure to be thrown.  The original exception will then
 157        *  be rethrown.
 158       */
 159       //@{
 160       /**
 161        *  @brief  Basic arithmetic inserters
 162        *  @param  A variable of builtin type.
 163        *  @return  @c *this if successful
 164        *
 165        *  These functions use the stream's current locale (specifically, the
 166        *  @c num_get facet) to perform numeric formatting.
 167       */
 168       __ostream_type&
 169       operator<<(long __n)
 170       { return _M_insert(__n); }
 171
 172       __ostream_type&
 173       operator<<(unsigned long __n)
 174       { return _M_insert(__n); }
 175
 176       __ostream_type&
 177       operator<<(bool __n)
 178       { return _M_insert(__n); }
 179
 180       __ostream_type&
 181       operator<<(short __n);
 182
 183       __ostream_type&
 184       operator<<(unsigned short __n)
 185       {
 186         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 187         // 117. basic_ostream uses nonexistent num_put member functions.
 188         return _M_insert(static_cast<unsigned long>(__n));
 189       }
 190
 191       __ostream_type&
 192       operator<<(int __n);
 193
 194       __ostream_type&
 195       operator<<(unsigned int __n)
 196       {
 197         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 198         // 117. basic_ostream uses nonexistent num_put member functions.
 199         return _M_insert(static_cast<unsigned long>(__n));
 200       }
 201
 202 #ifdef _GLIBCXX_USE_LONG_LONG
 203       __ostream_type&
 204       operator<<(long long __n)
 205       { return _M_insert(__n); }
 206
 207       __ostream_type&
 208       operator<<(unsigned long long __n)
 209       { return _M_insert(__n); }
 210 #endif
 211
 212       __ostream_type&
 213       operator<<(double __f)
 214       { return _M_insert(__f); }
 215
 216       __ostream_type&
 217       operator<<(float __f)
 218       {
 219         // _GLIBCXX_RESOLVE_LIB_DEFECTS
 220         // 117. basic_ostream uses nonexistent num_put member functions.
 221         return _M_insert(static_cast<double>(__f));
 222       }
 223
 224       __ostream_type&
 225       operator<<(long double __f)
 226       { return _M_insert(__f); }
 227
 228       __ostream_type&
 229       operator<<(const void* __p)
 230       { return _M_insert(__p); }
 231
 232       /**
 233        *  @brief  Extracting from another streambuf.
 234        *  @param  sb  A pointer to a streambuf
 235        *
 236        *  This function behaves like one of the basic arithmetic extractors,
 237        *  in that it also constructs a sentry object and has the same error
 238        *  handling behavior.
 239        *
 240        *  If @a sb is NULL, the stream will set failbit in its error state.
 241        *
 242        *  Characters are extracted from @a sb and inserted into @c *this
 243        *  until one of the following occurs:
 244        *
 245        *  - the input stream reaches end-of-file,
 246        *  - insertion into the output sequence fails (in this case, the
 247        *    character that would have been inserted is not extracted), or
 248        *  - an exception occurs while getting a character from @a sb, which
 249        *    sets failbit in the error state
 250        *
 251        *  If the function inserts no characters, failbit is set.
 252       */
 253       __ostream_type&
 254       operator<<(__streambuf_type* __sb);
 255       //@}
 256
 257       // [27.6.2.6] unformatted output functions
 258       /**
 259        *  @name Unformatted Output Functions
 260        *
 261        *  All the unformatted output functions have some common behavior.
 262        *  Each starts by constructing a temporary object of type
 263        *  std::basic_ostream::sentry.  This has several effects, concluding
 264        *  with the setting of a status flag; see the sentry documentation
 265        *  for more.
 266        *
 267        *  If the sentry status is good, the function tries to generate
 268        *  whatever data is appropriate for the type of the argument.
 269        *
 270        *  If an exception is thrown during insertion, ios_base::badbit
 271        *  will be turned on in the stream's error state.  If badbit is on in
 272        *  the stream's exceptions mask, the exception will be rethrown
 273        *  without completing its actions.
 274       */
 275       //@{
 276       /**
 277        *  @brief  Simple insertion.
 278        *  @param  c  The character to insert.
 279        *  @return  *this
 280        *
 281        *  Tries to insert @a c.
 282        *
 283        *  @note  This function is not overloaded on signed char and
 284        *         unsigned char.
 285       */
 286       __ostream_type&
 287       put(char_type __c);
 288
 289       // Core write functionality, without sentry.
 290       void
 291       _M_write(const char_type* __s, streamsize __n)
 292       {
 293         const streamsize __put = this->rdbuf()->sputn(__s, __n);
 294         if (__put != __n)
 295           this->setstate(ios_base::badbit);
 296       }
 297
 298       /**
 299        *  @brief  Character string insertion.
 300        *  @param  s  The array to insert.
 301        *  @param  n  Maximum number of characters to insert.
 302        *  @return  *this
 303        *
 304        *  Characters are copied from @a s and inserted into the stream until
 305        *  one of the following happens:
 306        *
 307        *  - @a n characters are inserted
 308        *  - inserting into the output sequence fails (in this case, badbit
 309        *    will be set in the stream's error state)
 310        *
 311        *  @note  This function is not overloaded on signed char and
 312        *         unsigned char.
 313       */
 314       __ostream_type&
 315       write(const char_type* __s, streamsize __n);
 316       //@}
 317
 318       /**
 319        *  @brief  Synchronizing the stream buffer.
 320        *  @return  *this
 321        *
 322        *  If @c rdbuf() is a null pointer, changes nothing.
 323        *
 324        *  Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
 325        *  sets badbit.
 326       */
 327       __ostream_type&
 328       flush();
 329
 330       // [27.6.2.4] seek members
 331       /**
 332        *  @brief  Getting the current write position.
 333        *  @return  A file position object.
 334        *
 335        *  If @c fail() is not false, returns @c pos_type(-1) to indicate
 336        *  failure.  Otherwise returns @c rdbuf()->pubseekoff(0,cur,out).
 337       */
 338       pos_type
 339       tellp();
 340
 341       /**
 342        *  @brief  Changing the current write position.
 343        *  @param  pos  A file position object.
 344        *  @return  *this
 345        *
 346        *  If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos).  If
 347        *  that function fails, sets failbit.
 348       */
 349       __ostream_type&
 350       seekp(pos_type);
 351
 352       /**
 353        *  @brief  Changing the current write position.
 354        *  @param  off  A file offset object.
 355        *  @param  dir  The direction in which to seek.
 356        *  @return  *this
 357        *
 358        *  If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir).
 359        *  If that function fails, sets failbit.
 360       */
 361        __ostream_type&
 362       seekp(off_type, ios_base::seekdir);
 363
 364     protected:
 365       explicit
 366       basic_ostream() { }
 367
 368       template<typename _ValueT>
 369         __ostream_type&
 370         _M_insert(_ValueT __v);
 371     };
 372
 373   /**
 374    *  @brief  Performs setup work for output streams.
 375    *
 376    *  Objects of this class are created before all of the standard
 377    *  inserters are run.  It is responsible for "exception-safe prefix and
 378    *  suffix operations."  Additional actions may be added by the
 379    *  implementation, and we list them in
 380    *  http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/howto.html#5
 381    *  under [27.6] notes.
 382   */
 383   template <typename _CharT, typename _Traits>
 384     class basic_ostream<_CharT, _Traits>::sentry
 385     {
 386       // Data Members:
 387       bool                              _M_ok;
 388       basic_ostream<_CharT, _Traits>&   _M_os;
 389
 390     public:
 391       /**
 392        *  @brief  The constructor performs preparatory work.
 393        *  @param  os  The output stream to guard.
 394        *
 395        *  If the stream state is good (@a os.good() is true), then if the
 396        *  stream is tied to another output stream, @c is.tie()->flush()
 397        *  is called to synchronize the output sequences.
 398        *
 399        *  If the stream state is still good, then the sentry state becomes
 400        *  true ("okay").
 401       */
 402       explicit
 403       sentry(basic_ostream<_CharT, _Traits>& __os);
 404
 405       /**
 406        *  @brief  Possibly flushes the stream.
 407        *
 408        *  If @c ios_base::unitbuf is set in @c os.flags(), and
 409        *  @c std::uncaught_exception() is true, the sentry destructor calls
 410        *  @c flush() on the output stream.
 411       */
 412       ~sentry()
 413       {
 414         // XXX MT
 415         if (_M_os.flags() & ios_base::unitbuf && !uncaught_exception())
 416           {
 417             // Can't call flush directly or else will get into recursive lock.
 418             if (_M_os.rdbuf() && _M_os.rdbuf()->pubsync() == -1)
 419               _M_os.setstate(ios_base::badbit);
 420           }
 421       }
 422
 423       /**
 424        *  @brief  Quick status checking.
 425        *  @return  The sentry state.
 426        *
 427        *  For ease of use, sentries may be converted to booleans.  The
 428        *  return value is that of the sentry state (true == okay).
 429       */
 430       operator bool() const
 431       { return _M_ok; }
 432     };
 433
 434   // [27.6.2.5.4] character insertion templates
 435   //@{
 436   /**
 437    *  @brief  Character inserters
 438    *  @param  out  An output stream.
 439    *  @param  c  A character.
 440    *  @return  out
 441    *
 442    *  Behaves like one of the formatted arithmetic inserters described in
 443    *  std::basic_ostream.  After constructing a sentry object with good
 444    *  status, this function inserts a single character and any required
 445    *  padding (as determined by [22.2.2.2.2]).  @c out.width(0) is then
 446    *  called.
 447    *
 448    *  If @a c is of type @c char and the character type of the stream is not
 449    *  @c char, the character is widened before insertion.
 450   */
 451   template<typename _CharT, typename _Traits>
 452     inline basic_ostream<_CharT, _Traits>&
 453     operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c)
 454     { return __ostream_insert(__out, &__c, 1); }
 455
 456   template<typename _CharT, typename _Traits>
 457     inline basic_ostream<_CharT, _Traits>&
 458     operator<<(basic_ostream<_CharT, _Traits>& __out, char __c)
 459     { return (__out << __out.widen(__c)); }
 460
 461   // Specialization
 462   template <class _Traits>
 463     inline basic_ostream<char, _Traits>&
 464     operator<<(basic_ostream<char, _Traits>& __out, char __c)
 465     { return __ostream_insert(__out, &__c, 1); }
 466
 467   // Signed and unsigned
 468   template<class _Traits>
 469     inline basic_ostream<char, _Traits>&
 470     operator<<(basic_ostream<char, _Traits>& __out, signed char __c)
 471     { return (__out << static_cast<char>(__c)); }
 472
 473   template<class _Traits>
 474     inline basic_ostream<char, _Traits>&
 475     operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c)
 476     { return (__out << static_cast<char>(__c)); }
 477   //@}
 478
 479   //@{
 480   /**
 481    *  @brief  String inserters
 482    *  @param  out  An output stream.
 483    *  @param  s  A character string.
 484    *  @return  out
 485    *  @pre  @a s must be a non-NULL pointer
 486    *
 487    *  Behaves like one of the formatted arithmetic inserters described in
 488    *  std::basic_ostream.  After constructing a sentry object with good
 489    *  status, this function inserts @c traits::length(s) characters starting
 490    *  at @a s, widened if necessary, followed by any required padding (as
 491    *  determined by [22.2.2.2.2]).  @c out.width(0) is then called.
 492   */
 493   template<typename _CharT, typename _Traits>
 494     inline basic_ostream<_CharT, _Traits>&
 495     operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s)
 496     {
 497       if (!__s)
 498         __out.setstate(ios_base::badbit);
 499       else
 500         __ostream_insert(__out, __s,
 501                          static_cast<streamsize>(_Traits::length(__s)));
 502       return __out;
 503     }
 504
 505   template<typename _CharT, typename _Traits>
 506     basic_ostream<_CharT, _Traits> &
 507     operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s);
 508
 509   // Partial specializationss
 510   template<class _Traits>
 511     inline basic_ostream<char, _Traits>&
 512     operator<<(basic_ostream<char, _Traits>& __out, const char* __s)
 513     {
 514       if (!__s)
 515         __out.setstate(ios_base::badbit);
 516       else
 517         __ostream_insert(__out, __s,
 518                          static_cast<streamsize>(_Traits::length(__s)));
 519       return __out;
 520     }
 521
 522   // Signed and unsigned
 523   template<class _Traits>
 524     inline basic_ostream<char, _Traits>&
 525     operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s)
 526     { return (__out << reinterpret_cast<const char*>(__s)); }
 527
 528   template<class _Traits>
 529     inline basic_ostream<char, _Traits> &
 530     operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s)
 531     { return (__out << reinterpret_cast<const char*>(__s)); }
 532   //@}
 533
 534   // [27.6.2.7] standard basic_ostream manipulators
 535   /**
 536    *  @brief  Write a newline and flush the stream.
 537    *
 538    *  This manipulator is often mistakenly used when a simple newline is
 539    *  desired, leading to poor buffering performance.  See
 540    *  http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2 for more
 541    *  on this subject.
 542   */
 543   template<typename _CharT, typename _Traits>
 544     inline basic_ostream<_CharT, _Traits>&
 545     endl(basic_ostream<_CharT, _Traits>& __os)
 546     { return flush(__os.put(__os.widen('\n'))); }
 547
 548   /**
 549    *  @brief  Write a null character into the output sequence.
 550    *
 551    *  "Null character" is @c CharT() by definition.  For CharT of @c char,
 552    *  this correctly writes the ASCII @c NUL character string terminator.
 553   */
 554   template<typename _CharT, typename _Traits>
 555     inline basic_ostream<_CharT, _Traits>&
 556     ends(basic_ostream<_CharT, _Traits>& __os)
 557     { return __os.put(_CharT()); }
 558
 559   /**
 560    *  @brief  Flushes the output stream.
 561    *
 562    *  This manipulator simply calls the stream's @c flush() member function.
 563   */
 564   template<typename _CharT, typename _Traits>
 565     inline basic_ostream<_CharT, _Traits>&
 566     flush(basic_ostream<_CharT, _Traits>& __os)
 567     { return __os.flush(); }
 568
 569 _GLIBCXX_END_NAMESPACE
 570
 571 #ifndef _GLIBCXX_EXPORT_TEMPLATE
 572 # include <bits/ostream.tcc>
 573 #endif
 574
 575 #endif  /* _GLIBCXX_OSTREAM */