libstdc++
ostream
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1 // Output streams -*- C++ -*-
2 
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
4 // 2006, 2007, 2008, 2009, 2010, 2011
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  // [27.6.2.1] Template class basic_ostream
48  /**
49  * @brief Controlling output.
50  * @ingroup io
51  *
52  * This is the base class for all output streams. It provides text
53  * formatting of all builtin types, and communicates with any class
54  * derived from basic_streambuf to do the actual output.
55  */
56  template<typename _CharT, typename _Traits>
57  class basic_ostream : virtual public basic_ios<_CharT, _Traits>
58  {
59  public:
60  // Types (inherited from basic_ios (27.4.4)):
61  typedef _CharT char_type;
62  typedef typename _Traits::int_type int_type;
63  typedef typename _Traits::pos_type pos_type;
64  typedef typename _Traits::off_type off_type;
65  typedef _Traits traits_type;
66 
67  // Non-standard Types:
68  typedef basic_streambuf<_CharT, _Traits> __streambuf_type;
69  typedef basic_ios<_CharT, _Traits> __ios_type;
70  typedef basic_ostream<_CharT, _Traits> __ostream_type;
71  typedef num_put<_CharT, ostreambuf_iterator<_CharT, _Traits> >
72  __num_put_type;
73  typedef ctype<_CharT> __ctype_type;
74 
75  // [27.6.2.2] constructor/destructor
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
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
94 
95  // [27.6.2.3] prefix/suffix
96  class sentry;
97  friend class sentry;
98 
99  // [27.6.2.5] formatted output
100  // [27.6.2.5.3] basic_ostream::operator<<
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&
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&
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&
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  // [27.6.2.5.2] arithmetic inserters
140  /**
141  * @name Arithmetic 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  * @brief Basic arithmetic inserters
160  * @param A variable of builtin type.
161  * @return @c *this if successful
162  *
163  * These functions use the stream's current locale (specifically, the
164  * @c num_get facet) to perform numeric formatting.
165  */
166  __ostream_type&
167  operator<<(long __n)
168  { return _M_insert(__n); }
169 
170  __ostream_type&
171  operator<<(unsigned long __n)
172  { return _M_insert(__n); }
173 
174  __ostream_type&
175  operator<<(bool __n)
176  { return _M_insert(__n); }
177 
178  __ostream_type&
179  operator<<(short __n);
180 
181  __ostream_type&
182  operator<<(unsigned short __n)
183  {
184  // _GLIBCXX_RESOLVE_LIB_DEFECTS
185  // 117. basic_ostream uses nonexistent num_put member functions.
186  return _M_insert(static_cast<unsigned long>(__n));
187  }
188 
189  __ostream_type&
190  operator<<(int __n);
191 
192  __ostream_type&
193  operator<<(unsigned int __n)
194  {
195  // _GLIBCXX_RESOLVE_LIB_DEFECTS
196  // 117. basic_ostream uses nonexistent num_put member functions.
197  return _M_insert(static_cast<unsigned long>(__n));
198  }
199 
200 #ifdef _GLIBCXX_USE_LONG_LONG
201  __ostream_type&
202  operator<<(long long __n)
203  { return _M_insert(__n); }
204 
205  __ostream_type&
206  operator<<(unsigned long long __n)
207  { return _M_insert(__n); }
208 #endif
209 
210  __ostream_type&
211  operator<<(double __f)
212  { return _M_insert(__f); }
213 
214  __ostream_type&
215  operator<<(float __f)
216  {
217  // _GLIBCXX_RESOLVE_LIB_DEFECTS
218  // 117. basic_ostream uses nonexistent num_put member functions.
219  return _M_insert(static_cast<double>(__f));
220  }
221 
222  __ostream_type&
223  operator<<(long double __f)
224  { return _M_insert(__f); }
225 
226  __ostream_type&
227  operator<<(const void* __p)
228  { return _M_insert(__p); }
229 
230  /**
231  * @brief Extracting from another streambuf.
232  * @param sb A pointer to a streambuf
233  *
234  * This function behaves like one of the basic arithmetic extractors,
235  * in that it also constructs a sentry object and has the same error
236  * handling behavior.
237  *
238  * If @a sb is NULL, the stream will set failbit in its error state.
239  *
240  * Characters are extracted from @a sb and inserted into @c *this
241  * until one of the following occurs:
242  *
243  * - the input stream reaches end-of-file,
244  * - insertion into the output sequence fails (in this case, the
245  * character that would have been inserted is not extracted), or
246  * - an exception occurs while getting a character from @a sb, which
247  * sets failbit in the error state
248  *
249  * If the function inserts no characters, failbit is set.
250  */
251  __ostream_type&
252  operator<<(__streambuf_type* __sb);
253  //@}
254 
255  // [27.6.2.6] unformatted output functions
256  /**
257  * @name Unformatted Output Functions
258  *
259  * All the unformatted output functions have some common behavior.
260  * Each starts by constructing a temporary object of type
261  * std::basic_ostream::sentry. This has several effects, concluding
262  * with the setting of a status flag; see the sentry documentation
263  * for more.
264  *
265  * If the sentry status is good, the function tries to generate
266  * whatever data is appropriate for the type of the argument.
267  *
268  * If an exception is thrown during insertion, ios_base::badbit
269  * will be turned on in the stream's error state. If badbit is on in
270  * the stream's exceptions mask, the exception will be rethrown
271  * without completing its actions.
272  */
273  //@{
274  /**
275  * @brief Simple insertion.
276  * @param c The character to insert.
277  * @return *this
278  *
279  * Tries to insert @a c.
280  *
281  * @note This function is not overloaded on signed char and
282  * unsigned char.
283  */
284  __ostream_type&
285  put(char_type __c);
286 
287  // Core write functionality, without sentry.
288  void
289  _M_write(const char_type* __s, streamsize __n)
290  {
291  const streamsize __put = this->rdbuf()->sputn(__s, __n);
292  if (__put != __n)
293  this->setstate(ios_base::badbit);
294  }
295 
296  /**
297  * @brief Character string insertion.
298  * @param s The array to insert.
299  * @param n Maximum number of characters to insert.
300  * @return *this
301  *
302  * Characters are copied from @a s and inserted into the stream until
303  * one of the following happens:
304  *
305  * - @a n characters are inserted
306  * - inserting into the output sequence fails (in this case, badbit
307  * will be set in the stream's error state)
308  *
309  * @note This function is not overloaded on signed char and
310  * unsigned char.
311  */
312  __ostream_type&
313  write(const char_type* __s, streamsize __n);
314  //@}
315 
316  /**
317  * @brief Synchronizing the stream buffer.
318  * @return *this
319  *
320  * If @c rdbuf() is a null pointer, changes nothing.
321  *
322  * Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1,
323  * sets badbit.
324  */
325  __ostream_type&
326  flush();
327 
328  // [27.6.2.4] seek members
329  /**
330  * @brief Getting the current write position.
331  * @return A file position object.
332  *
333  * If @c fail() is not false, returns @c pos_type(-1) to indicate
334  * failure. Otherwise returns @c rdbuf()->pubseekoff(0,cur,out).
335  */
336  pos_type
337  tellp();
338 
339  /**
340  * @brief Changing the current write position.
341  * @param pos A file position object.
342  * @return *this
343  *
344  * If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos). If
345  * that function fails, sets failbit.
346  */
347  __ostream_type&
348  seekp(pos_type);
349 
350  /**
351  * @brief Changing the current write position.
352  * @param off A file offset object.
353  * @param dir The direction in which to seek.
354  * @return *this
355  *
356  * If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir).
357  * If that function fails, sets failbit.
358  */
359  __ostream_type&
360  seekp(off_type, ios_base::seekdir);
361 
362  protected:
363  basic_ostream()
364  { this->init(0); }
365 
366  template<typename _ValueT>
367  __ostream_type&
368  _M_insert(_ValueT __v);
369  };
370 
371  /**
372  * @brief Performs setup work for output streams.
373  *
374  * Objects of this class are created before all of the standard
375  * inserters are run. It is responsible for <em>exception-safe prefix and
376  * suffix operations</em>.
377  */
378  template <typename _CharT, typename _Traits>
379  class basic_ostream<_CharT, _Traits>::sentry
380  {
381  // Data Members.
382  bool _M_ok;
384 
385  public:
386  /**
387  * @brief The constructor performs preparatory work.
388  * @param os The output stream to guard.
389  *
390  * If the stream state is good (@a os.good() is true), then if the
391  * stream is tied to another output stream, @c is.tie()->flush()
392  * is called to synchronize the output sequences.
393  *
394  * If the stream state is still good, then the sentry state becomes
395  * true (@a okay).
396  */
397  explicit
399 
400  /**
401  * @brief Possibly flushes the stream.
402  *
403  * If @c ios_base::unitbuf is set in @c os.flags(), and
404  * @c std::uncaught_exception() is true, the sentry destructor calls
405  * @c flush() on the output stream.
406  */
408  {
409  // XXX MT
410  if (bool(_M_os.flags() & ios_base::unitbuf) && !uncaught_exception())
411  {
412  // Can't call flush directly or else will get into recursive lock.
413  if (_M_os.rdbuf() && _M_os.rdbuf()->pubsync() == -1)
414  _M_os.setstate(ios_base::badbit);
415  }
416  }
417 
418  /**
419  * @brief Quick status checking.
420  * @return The sentry state.
421  *
422  * For ease of use, sentries may be converted to booleans. The
423  * return value is that of the sentry state (true == okay).
424  */
425 #ifdef __GXX_EXPERIMENTAL_CXX0X__
426  explicit
427 #endif
428  operator bool() const
429  { return _M_ok; }
430  };
431 
432  // [27.6.2.5.4] character insertion templates
433  //@{
434  /**
435  * @brief Character inserters
436  * @param out An output stream.
437  * @param c A character.
438  * @return out
439  *
440  * Behaves like one of the formatted arithmetic inserters described in
441  * std::basic_ostream. After constructing a sentry object with good
442  * status, this function inserts a single character and any required
443  * padding (as determined by [22.2.2.2.2]). @c out.width(0) is then
444  * called.
445  *
446  * If @a c is of type @c char and the character type of the stream is not
447  * @c char, the character is widened before insertion.
448  */
449  template<typename _CharT, typename _Traits>
451  operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c)
452  { return __ostream_insert(__out, &__c, 1); }
453 
454  template<typename _CharT, typename _Traits>
455  inline basic_ostream<_CharT, _Traits>&
456  operator<<(basic_ostream<_CharT, _Traits>& __out, char __c)
457  { return (__out << __out.widen(__c)); }
458 
459  // Specialization
460  template <class _Traits>
461  inline basic_ostream<char, _Traits>&
462  operator<<(basic_ostream<char, _Traits>& __out, char __c)
463  { return __ostream_insert(__out, &__c, 1); }
464 
465  // Signed and unsigned
466  template<class _Traits>
467  inline basic_ostream<char, _Traits>&
468  operator<<(basic_ostream<char, _Traits>& __out, signed char __c)
469  { return (__out << static_cast<char>(__c)); }
470 
471  template<class _Traits>
472  inline basic_ostream<char, _Traits>&
473  operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c)
474  { return (__out << static_cast<char>(__c)); }
475  //@}
476 
477  //@{
478  /**
479  * @brief String inserters
480  * @param out An output stream.
481  * @param s A character string.
482  * @return out
483  * @pre @a s must be a non-NULL pointer
484  *
485  * Behaves like one of the formatted arithmetic inserters described in
486  * std::basic_ostream. After constructing a sentry object with good
487  * status, this function inserts @c traits::length(s) characters starting
488  * at @a s, widened if necessary, followed by any required padding (as
489  * determined by [22.2.2.2.2]). @c out.width(0) is then called.
490  */
491  template<typename _CharT, typename _Traits>
492  inline basic_ostream<_CharT, _Traits>&
493  operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s)
494  {
495  if (!__s)
496  __out.setstate(ios_base::badbit);
497  else
498  __ostream_insert(__out, __s,
499  static_cast<streamsize>(_Traits::length(__s)));
500  return __out;
501  }
502 
503  template<typename _CharT, typename _Traits>
504  basic_ostream<_CharT, _Traits> &
505  operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s);
506 
507  // Partial specializations
508  template<class _Traits>
509  inline basic_ostream<char, _Traits>&
510  operator<<(basic_ostream<char, _Traits>& __out, const char* __s)
511  {
512  if (!__s)
513  __out.setstate(ios_base::badbit);
514  else
515  __ostream_insert(__out, __s,
516  static_cast<streamsize>(_Traits::length(__s)));
517  return __out;
518  }
519 
520  // Signed and unsigned
521  template<class _Traits>
522  inline basic_ostream<char, _Traits>&
523  operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s)
524  { return (__out << reinterpret_cast<const char*>(__s)); }
525 
526  template<class _Traits>
527  inline basic_ostream<char, _Traits> &
528  operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s)
529  { return (__out << reinterpret_cast<const char*>(__s)); }
530  //@}
531 
532  // [27.6.2.7] standard basic_ostream manipulators
533  /**
534  * @brief Write a newline and flush the stream.
535  *
536  * This manipulator is often mistakenly used when a simple newline is
537  * desired, leading to poor buffering performance. See
538  * http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html
539  * for more on this subject.
540  */
541  template<typename _CharT, typename _Traits>
542  inline basic_ostream<_CharT, _Traits>&
544  { return flush(__os.put(__os.widen('\n'))); }
545 
546  /**
547  * @brief Write a null character into the output sequence.
548  *
549  * <em>Null character</em> is @c CharT() by definition. For CharT of @c char,
550  * this correctly writes the ASCII @c NUL character string terminator.
551  */
552  template<typename _CharT, typename _Traits>
553  inline basic_ostream<_CharT, _Traits>&
555  { return __os.put(_CharT()); }
556 
557  /**
558  * @brief Flushes the output stream.
559  *
560  * This manipulator simply calls the stream's @c flush() member function.
561  */
562  template<typename _CharT, typename _Traits>
563  inline basic_ostream<_CharT, _Traits>&
565  { return __os.flush(); }
566 
567 #ifdef __GXX_EXPERIMENTAL_CXX0X__
568  // [27.7.2.9] Rvalue stream insertion
569  /**
570  * @brief Generic inserter for rvalue stream
571  * @param os An input stream.
572  * @param x A reference to the object being inserted.
573  * @return os
574  *
575  * This is just a forwarding function to allow insertion to
576  * rvalue streams since they won't bind to the inserter functions
577  * that take an lvalue reference.
578  */
579  template<typename _CharT, typename _Traits, typename _Tp>
580  inline basic_ostream<_CharT, _Traits>&
581  operator<<(basic_ostream<_CharT, _Traits>&& __os, const _Tp& __x)
582  { return (__os << __x); }
583 #endif // __GXX_EXPERIMENTAL_CXX0X__
584 
585 _GLIBCXX_END_NAMESPACE_VERSION
586 } // namespace
587 
588 #include <bits/ostream.tcc>
589 
590 #endif /* _GLIBCXX_OSTREAM */