ostream

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00001 // Output streams -*- C++ -*-
00002 
00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
00004 // 2006, 2007, 2008, 2009
00005 // Free Software Foundation, Inc.
00006 //
00007 // This file is part of the GNU ISO C++ Library.  This library is free
00008 // software; you can redistribute it and/or modify it under the
00009 // terms of the GNU General Public License as published by the
00010 // Free Software Foundation; either version 3, or (at your option)
00011 // any later version.
00012 
00013 // This library is distributed in the hope that it will be useful,
00014 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00015 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00016 // GNU General Public License for more details.
00017 
00018 // Under Section 7 of GPL version 3, you are granted additional
00019 // permissions described in the GCC Runtime Library Exception, version
00020 // 3.1, as published by the Free Software Foundation.
00021 
00022 // You should have received a copy of the GNU General Public License and
00023 // a copy of the GCC Runtime Library Exception along with this program;
00024 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00025 // <http://www.gnu.org/licenses/>.
00026 
00027 /** @file ostream
00028  *  This is a Standard C++ Library header.
00029  */
00030 
00031 //
00032 // ISO C++ 14882: 27.6.2  Output streams
00033 //
00034 
00035 #ifndef _GLIBCXX_OSTREAM
00036 #define _GLIBCXX_OSTREAM 1
00037 
00038 #pragma GCC system_header
00039 
00040 #include <ios>
00041 #include <bits/ostream_insert.h>
00042 
00043 _GLIBCXX_BEGIN_NAMESPACE(std)
00044 
00045   // [27.6.2.1] Template class basic_ostream
00046   /**
00047    *  @brief  Controlling output.
00048    *  @ingroup io
00049    *
00050    *  This is the base class for all output streams.  It provides text
00051    *  formatting of all builtin types, and communicates with any class
00052    *  derived from basic_streambuf to do the actual output.
00053   */
00054   template<typename _CharT, typename _Traits>
00055     class basic_ostream : virtual public basic_ios<_CharT, _Traits>
00056     {
00057     public:
00058       // Types (inherited from basic_ios (27.4.4)):
00059       typedef _CharT                            char_type;
00060       typedef typename _Traits::int_type        int_type;
00061       typedef typename _Traits::pos_type        pos_type;
00062       typedef typename _Traits::off_type        off_type;
00063       typedef _Traits                           traits_type;
00064       
00065       // Non-standard Types:
00066       typedef basic_streambuf<_CharT, _Traits>      __streambuf_type;
00067       typedef basic_ios<_CharT, _Traits>        __ios_type;
00068       typedef basic_ostream<_CharT, _Traits>        __ostream_type;
00069       typedef num_put<_CharT, ostreambuf_iterator<_CharT, _Traits> >        
00070                                 __num_put_type;
00071       typedef ctype<_CharT>                     __ctype_type;
00072 
00073       // [27.6.2.2] constructor/destructor
00074       /**
00075        *  @brief  Base constructor.
00076        *
00077        *  This ctor is almost never called by the user directly, rather from
00078        *  derived classes' initialization lists, which pass a pointer to
00079        *  their own stream buffer.
00080       */
00081       explicit 
00082       basic_ostream(__streambuf_type* __sb)
00083       { this->init(__sb); }
00084 
00085       /**
00086        *  @brief  Base destructor.
00087        *
00088        *  This does very little apart from providing a virtual base dtor.
00089       */
00090       virtual 
00091       ~basic_ostream() { }
00092 
00093       // [27.6.2.3] prefix/suffix
00094       class sentry;
00095       friend class sentry;
00096       
00097       // [27.6.2.5] formatted output
00098       // [27.6.2.5.3]  basic_ostream::operator<<
00099       //@{
00100       /**
00101        *  @brief  Interface for manipulators.
00102        *
00103        *  Manipulators such as @c std::endl and @c std::hex use these
00104        *  functions in constructs like "std::cout << std::endl".  For more
00105        *  information, see the iomanip header.
00106       */
00107       __ostream_type&
00108       operator<<(__ostream_type& (*__pf)(__ostream_type&))
00109       {
00110     // _GLIBCXX_RESOLVE_LIB_DEFECTS
00111     // DR 60. What is a formatted input function?
00112     // The inserters for manipulators are *not* formatted output functions.
00113     return __pf(*this);
00114       }
00115 
00116       __ostream_type&
00117       operator<<(__ios_type& (*__pf)(__ios_type&))
00118       {
00119     // _GLIBCXX_RESOLVE_LIB_DEFECTS
00120     // DR 60. What is a formatted input function?
00121     // The inserters for manipulators are *not* formatted output functions.
00122     __pf(*this);
00123     return *this;
00124       }
00125 
00126       __ostream_type&
00127       operator<<(ios_base& (*__pf) (ios_base&))
00128       {
00129     // _GLIBCXX_RESOLVE_LIB_DEFECTS
00130     // DR 60. What is a formatted input function?
00131     // The inserters for manipulators are *not* formatted output functions.
00132     __pf(*this);
00133     return *this;
00134       }
00135       //@}
00136 
00137       // [27.6.2.5.2] arithmetic inserters
00138       /**
00139        *  @name Arithmetic Inserters
00140        *
00141        *  All the @c operator<< functions (aka <em>formatted output
00142        *  functions</em>) have some common behavior.  Each starts by
00143        *  constructing a temporary object of type std::basic_ostream::sentry.
00144        *  This can have several effects, concluding with the setting of a
00145        *  status flag; see the sentry documentation for more.
00146        *
00147        *  If the sentry status is good, the function tries to generate
00148        *  whatever data is appropriate for the type of the argument.
00149        *
00150        *  If an exception is thrown during insertion, ios_base::badbit
00151        *  will be turned on in the stream's error state without causing an
00152        *  ios_base::failure to be thrown.  The original exception will then
00153        *  be rethrown.
00154       */
00155       //@{
00156       /**
00157        *  @brief  Basic arithmetic inserters
00158        *  @param  A variable of builtin type.
00159        *  @return  @c *this if successful
00160        *
00161        *  These functions use the stream's current locale (specifically, the
00162        *  @c num_get facet) to perform numeric formatting.
00163       */
00164       __ostream_type& 
00165       operator<<(long __n)
00166       { return _M_insert(__n); }
00167       
00168       __ostream_type& 
00169       operator<<(unsigned long __n)
00170       { return _M_insert(__n); }    
00171 
00172       __ostream_type& 
00173       operator<<(bool __n)
00174       { return _M_insert(__n); }
00175 
00176       __ostream_type& 
00177       operator<<(short __n);
00178 
00179       __ostream_type& 
00180       operator<<(unsigned short __n)
00181       {
00182     // _GLIBCXX_RESOLVE_LIB_DEFECTS
00183     // 117. basic_ostream uses nonexistent num_put member functions.
00184     return _M_insert(static_cast<unsigned long>(__n));
00185       }
00186 
00187       __ostream_type& 
00188       operator<<(int __n);
00189 
00190       __ostream_type& 
00191       operator<<(unsigned int __n)
00192       {
00193     // _GLIBCXX_RESOLVE_LIB_DEFECTS
00194     // 117. basic_ostream uses nonexistent num_put member functions.
00195     return _M_insert(static_cast<unsigned long>(__n));
00196       }
00197 
00198 #ifdef _GLIBCXX_USE_LONG_LONG
00199       __ostream_type& 
00200       operator<<(long long __n)
00201       { return _M_insert(__n); }
00202 
00203       __ostream_type& 
00204       operator<<(unsigned long long __n)
00205       { return _M_insert(__n); }    
00206 #endif
00207 
00208       __ostream_type& 
00209       operator<<(double __f)
00210       { return _M_insert(__f); }
00211 
00212       __ostream_type& 
00213       operator<<(float __f)
00214       {
00215     // _GLIBCXX_RESOLVE_LIB_DEFECTS
00216     // 117. basic_ostream uses nonexistent num_put member functions.
00217     return _M_insert(static_cast<double>(__f));
00218       }
00219 
00220       __ostream_type& 
00221       operator<<(long double __f)
00222       { return _M_insert(__f); }
00223 
00224       __ostream_type& 
00225       operator<<(const void* __p)
00226       { return _M_insert(__p); }
00227 
00228       /**
00229        *  @brief  Extracting from another streambuf.
00230        *  @param  sb  A pointer to a streambuf
00231        *
00232        *  This function behaves like one of the basic arithmetic extractors,
00233        *  in that it also constructs a sentry object and has the same error
00234        *  handling behavior.
00235        *
00236        *  If @a sb is NULL, the stream will set failbit in its error state.
00237        *
00238        *  Characters are extracted from @a sb and inserted into @c *this
00239        *  until one of the following occurs:
00240        *
00241        *  - the input stream reaches end-of-file,
00242        *  - insertion into the output sequence fails (in this case, the
00243        *    character that would have been inserted is not extracted), or
00244        *  - an exception occurs while getting a character from @a sb, which
00245        *    sets failbit in the error state
00246        *
00247        *  If the function inserts no characters, failbit is set.
00248       */
00249       __ostream_type& 
00250       operator<<(__streambuf_type* __sb);
00251       //@}
00252 
00253       // [27.6.2.6] unformatted output functions
00254       /**
00255        *  @name Unformatted Output Functions
00256        *
00257        *  All the unformatted output functions have some common behavior.
00258        *  Each starts by constructing a temporary object of type
00259        *  std::basic_ostream::sentry.  This has several effects, concluding
00260        *  with the setting of a status flag; see the sentry documentation
00261        *  for more.
00262        *
00263        *  If the sentry status is good, the function tries to generate
00264        *  whatever data is appropriate for the type of the argument.
00265        *
00266        *  If an exception is thrown during insertion, ios_base::badbit
00267        *  will be turned on in the stream's error state.  If badbit is on in
00268        *  the stream's exceptions mask, the exception will be rethrown
00269        *  without completing its actions.
00270       */
00271       //@{
00272       /**
00273        *  @brief  Simple insertion.
00274        *  @param  c  The character to insert.
00275        *  @return  *this
00276        *
00277        *  Tries to insert @a c.
00278        *
00279        *  @note  This function is not overloaded on signed char and
00280        *         unsigned char.
00281       */
00282       __ostream_type& 
00283       put(char_type __c);
00284 
00285       // Core write functionality, without sentry.
00286       void
00287       _M_write(const char_type* __s, streamsize __n)
00288       {
00289     const streamsize __put = this->rdbuf()->sputn(__s, __n);
00290     if (__put != __n)
00291       this->setstate(ios_base::badbit);
00292       }
00293 
00294       /**
00295        *  @brief  Character string insertion.
00296        *  @param  s  The array to insert.
00297        *  @param  n  Maximum number of characters to insert.
00298        *  @return  *this
00299        *
00300        *  Characters are copied from @a s and inserted into the stream until
00301        *  one of the following happens:
00302        *
00303        *  - @a n characters are inserted
00304        *  - inserting into the output sequence fails (in this case, badbit
00305        *    will be set in the stream's error state)
00306        *
00307        *  @note  This function is not overloaded on signed char and
00308        *         unsigned char.
00309       */
00310       __ostream_type& 
00311       write(const char_type* __s, streamsize __n);
00312       //@}
00313 
00314       /**
00315        *  @brief  Synchronizing the stream buffer.
00316        *  @return  *this
00317        *
00318        *  If @c rdbuf() is a null pointer, changes nothing.
00319        *
00320        *  Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
00321        *  sets badbit.
00322       */
00323       __ostream_type& 
00324       flush();
00325 
00326       // [27.6.2.4] seek members
00327       /**
00328        *  @brief  Getting the current write position.
00329        *  @return  A file position object.
00330        *
00331        *  If @c fail() is not false, returns @c pos_type(-1) to indicate
00332        *  failure.  Otherwise returns @c rdbuf()->pubseekoff(0,cur,out).
00333       */
00334       pos_type 
00335       tellp();
00336 
00337       /**
00338        *  @brief  Changing the current write position.
00339        *  @param  pos  A file position object.
00340        *  @return  *this
00341        *
00342        *  If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos).  If
00343        *  that function fails, sets failbit.
00344       */
00345       __ostream_type& 
00346       seekp(pos_type);
00347 
00348       /**
00349        *  @brief  Changing the current write position.
00350        *  @param  off  A file offset object.
00351        *  @param  dir  The direction in which to seek.
00352        *  @return  *this
00353        *
00354        *  If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir).
00355        *  If that function fails, sets failbit.
00356       */
00357        __ostream_type& 
00358       seekp(off_type, ios_base::seekdir);
00359       
00360     protected:
00361       basic_ostream()
00362       { this->init(0); }
00363 
00364       template<typename _ValueT>
00365         __ostream_type&
00366         _M_insert(_ValueT __v);
00367     };
00368 
00369   /**
00370    *  @brief  Performs setup work for output streams.
00371    *
00372    *  Objects of this class are created before all of the standard
00373    *  inserters are run.  It is responsible for "exception-safe prefix and
00374    *  suffix operations." 
00375   */
00376   template <typename _CharT, typename _Traits>
00377     class basic_ostream<_CharT, _Traits>::sentry
00378     {
00379       // Data Members:
00380       bool              _M_ok;
00381       basic_ostream<_CharT, _Traits>&   _M_os;
00382       
00383     public:
00384       /**
00385        *  @brief  The constructor performs preparatory work.
00386        *  @param  os  The output stream to guard.
00387        *
00388        *  If the stream state is good (@a os.good() is true), then if the
00389        *  stream is tied to another output stream, @c is.tie()->flush()
00390        *  is called to synchronize the output sequences.
00391        *
00392        *  If the stream state is still good, then the sentry state becomes
00393        *  true ("okay").
00394       */
00395       explicit
00396       sentry(basic_ostream<_CharT, _Traits>& __os);
00397 
00398       /**
00399        *  @brief  Possibly flushes the stream.
00400        *
00401        *  If @c ios_base::unitbuf is set in @c os.flags(), and
00402        *  @c std::uncaught_exception() is true, the sentry destructor calls
00403        *  @c flush() on the output stream.
00404       */
00405       ~sentry()
00406       {
00407     // XXX MT
00408     if (bool(_M_os.flags() & ios_base::unitbuf) && !uncaught_exception())
00409       {
00410         // Can't call flush directly or else will get into recursive lock.
00411         if (_M_os.rdbuf() && _M_os.rdbuf()->pubsync() == -1)
00412           _M_os.setstate(ios_base::badbit);
00413       }
00414       }
00415 
00416       /**
00417        *  @brief  Quick status checking.
00418        *  @return  The sentry state.
00419        *
00420        *  For ease of use, sentries may be converted to booleans.  The
00421        *  return value is that of the sentry state (true == okay).
00422       */
00423       operator bool() const
00424       { return _M_ok; }
00425     };
00426 
00427   // [27.6.2.5.4] character insertion templates
00428   //@{
00429   /**
00430    *  @brief  Character inserters
00431    *  @param  out  An output stream.
00432    *  @param  c  A character.
00433    *  @return  out
00434    *
00435    *  Behaves like one of the formatted arithmetic inserters described in
00436    *  std::basic_ostream.  After constructing a sentry object with good
00437    *  status, this function inserts a single character and any required
00438    *  padding (as determined by [22.2.2.2.2]).  @c out.width(0) is then
00439    *  called.
00440    *
00441    *  If @a c is of type @c char and the character type of the stream is not
00442    *  @c char, the character is widened before insertion.
00443   */
00444   template<typename _CharT, typename _Traits>
00445     inline basic_ostream<_CharT, _Traits>&
00446     operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c)
00447     { return __ostream_insert(__out, &__c, 1); }
00448 
00449   template<typename _CharT, typename _Traits>
00450     inline basic_ostream<_CharT, _Traits>&
00451     operator<<(basic_ostream<_CharT, _Traits>& __out, char __c)
00452     { return (__out << __out.widen(__c)); }
00453 
00454   // Specialization
00455   template <class _Traits> 
00456     inline basic_ostream<char, _Traits>&
00457     operator<<(basic_ostream<char, _Traits>& __out, char __c)
00458     { return __ostream_insert(__out, &__c, 1); }
00459 
00460   // Signed and unsigned
00461   template<class _Traits>
00462     inline basic_ostream<char, _Traits>&
00463     operator<<(basic_ostream<char, _Traits>& __out, signed char __c)
00464     { return (__out << static_cast<char>(__c)); }
00465   
00466   template<class _Traits>
00467     inline basic_ostream<char, _Traits>&
00468     operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c)
00469     { return (__out << static_cast<char>(__c)); }
00470   //@}
00471   
00472   //@{
00473   /**
00474    *  @brief  String inserters
00475    *  @param  out  An output stream.
00476    *  @param  s  A character string.
00477    *  @return  out
00478    *  @pre  @a s must be a non-NULL pointer
00479    *
00480    *  Behaves like one of the formatted arithmetic inserters described in
00481    *  std::basic_ostream.  After constructing a sentry object with good
00482    *  status, this function inserts @c traits::length(s) characters starting
00483    *  at @a s, widened if necessary, followed by any required padding (as
00484    *  determined by [22.2.2.2.2]).  @c out.width(0) is then called.
00485   */
00486   template<typename _CharT, typename _Traits>
00487     inline basic_ostream<_CharT, _Traits>&
00488     operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s)
00489     {
00490       if (!__s)
00491     __out.setstate(ios_base::badbit);
00492       else
00493     __ostream_insert(__out, __s,
00494              static_cast<streamsize>(_Traits::length(__s)));
00495       return __out;
00496     }
00497 
00498   template<typename _CharT, typename _Traits>
00499     basic_ostream<_CharT, _Traits> &
00500     operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s);
00501 
00502   // Partial specializations
00503   template<class _Traits>
00504     inline basic_ostream<char, _Traits>&
00505     operator<<(basic_ostream<char, _Traits>& __out, const char* __s)
00506     {
00507       if (!__s)
00508     __out.setstate(ios_base::badbit);
00509       else
00510     __ostream_insert(__out, __s,
00511              static_cast<streamsize>(_Traits::length(__s)));
00512       return __out;
00513     }
00514 
00515   // Signed and unsigned
00516   template<class _Traits>
00517     inline basic_ostream<char, _Traits>&
00518     operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s)
00519     { return (__out << reinterpret_cast<const char*>(__s)); }
00520 
00521   template<class _Traits>
00522     inline basic_ostream<char, _Traits> &
00523     operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s)
00524     { return (__out << reinterpret_cast<const char*>(__s)); }
00525   //@}
00526 
00527   // [27.6.2.7] standard basic_ostream manipulators
00528   /**
00529    *  @brief  Write a newline and flush the stream.
00530    *
00531    *  This manipulator is often mistakenly used when a simple newline is
00532    *  desired, leading to poor buffering performance.  See
00533    *  http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2 for more
00534    *  on this subject.
00535   */
00536   template<typename _CharT, typename _Traits>
00537     inline basic_ostream<_CharT, _Traits>& 
00538     endl(basic_ostream<_CharT, _Traits>& __os)
00539     { return flush(__os.put(__os.widen('\n'))); }
00540 
00541   /**
00542    *  @brief  Write a null character into the output sequence.
00543    *
00544    *  "Null character" is @c CharT() by definition.  For CharT of @c char,
00545    *  this correctly writes the ASCII @c NUL character string terminator.
00546   */
00547   template<typename _CharT, typename _Traits>
00548     inline basic_ostream<_CharT, _Traits>& 
00549     ends(basic_ostream<_CharT, _Traits>& __os)
00550     { return __os.put(_CharT()); }
00551   
00552   /**
00553    *  @brief  Flushes the output stream.
00554    *
00555    *  This manipulator simply calls the stream's @c flush() member function.
00556   */
00557   template<typename _CharT, typename _Traits>
00558     inline basic_ostream<_CharT, _Traits>& 
00559     flush(basic_ostream<_CharT, _Traits>& __os)
00560     { return __os.flush(); }
00561 
00562 _GLIBCXX_END_NAMESPACE
00563 
00564 #ifndef _GLIBCXX_EXPORT_TEMPLATE
00565 # include <bits/ostream.tcc>
00566 #endif
00567 
00568 #endif  /* _GLIBCXX_OSTREAM */

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