The C and C++ Include Header Files

/usr/include/c++/11/bits/stream_iterator.h


$ cat -n /usr/include/c++/11/bits/stream_iterator.h

     1	// Stream iterators
     2	
     3	// Copyright (C) 2001-2021 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 bits/stream_iterator.h
    26	 *  This is an internal header file, included by other library headers.
    27	 *  Do not attempt to use it directly. @headername{iterator}
    28	 */
    29	
    30	#ifndef _STREAM_ITERATOR_H
    31	#define _STREAM_ITERATOR_H 1
    32	
    33	#pragma GCC system_header
    34	
    35	#include <debug/debug.h>
    36	
    37	namespace std _GLIBCXX_VISIBILITY(default)
    38	{
    39	_GLIBCXX_BEGIN_NAMESPACE_VERSION
    40	
    41	  /**
    42	   * @addtogroup iterators
    43	   * @{
    44	   */
    45	
    46	  /// Provides input iterator semantics for streams.
    47	  template<typename _Tp, typename _CharT = char,
    48	           typename _Traits = char_traits<_CharT>, typename _Dist = ptrdiff_t>
    49	    class istream_iterator
    50	    : public iterator<input_iterator_tag, _Tp, _Dist, const _Tp*, const _Tp&>
    51	    {
    52	    public:
    53	      typedef _CharT                         char_type;
    54	      typedef _Traits                        traits_type;
    55	      typedef basic_istream<_CharT, _Traits> istream_type;
    56	
    57	    private:
    58	      istream_type*	_M_stream;
    59	      _Tp		_M_value;
    60	      // This bool becomes false at end-of-stream. It should be sufficient to
    61	      // check _M_stream != nullptr instead, but historically we did not set
    62	      // _M_stream to null when reaching the end, so we need to keep this flag.
    63	      bool		_M_ok;
    64	
    65	    public:
    66	      ///  Construct end of input stream iterator.
    67	      _GLIBCXX_CONSTEXPR istream_iterator()
    68	      : _M_stream(0), _M_value(), _M_ok(false) {}
    69	
    70	      ///  Construct start of input stream iterator.
    71	      istream_iterator(istream_type& __s)
    72	      : _M_stream(std::__addressof(__s)), _M_ok(true)
    73	      { _M_read(); }
    74	
    75	      istream_iterator(const istream_iterator& __obj)
    76	      : _M_stream(__obj._M_stream), _M_value(__obj._M_value),
    77	        _M_ok(__obj._M_ok)
    78	      { }
    79	
    80	#if __cplusplus > 201703L && __cpp_lib_concepts
    81	      constexpr
    82	      istream_iterator(default_sentinel_t)
    83	      noexcept(is_nothrow_default_constructible_v<_Tp>)
    84	      : istream_iterator() { }
    85	#endif
    86	
    87	#if __cplusplus >= 201103L
    88	      istream_iterator& operator=(const istream_iterator&) = default;
    89	      ~istream_iterator() = default;
    90	#endif
    91	
    92	      const _Tp&
    93	      operator*() const
    94	      {
    95		__glibcxx_requires_cond(_M_ok,
    96					_M_message(__gnu_debug::__msg_deref_istream)
    97					._M_iterator(*this));
    98		return _M_value;
    99	      }
   100	
   101	      const _Tp*
   102	      operator->() const { return std::__addressof((operator*())); }
   103	
   104	      istream_iterator&
   105	      operator++()
   106	      {
   107		__glibcxx_requires_cond(_M_ok,
   108					_M_message(__gnu_debug::__msg_inc_istream)
   109					._M_iterator(*this));
   110		_M_read();
   111		return *this;
   112	      }
   113	
   114	      istream_iterator
   115	      operator++(int)
   116	      {
   117		__glibcxx_requires_cond(_M_ok,
   118					_M_message(__gnu_debug::__msg_inc_istream)
   119					._M_iterator(*this));
   120		istream_iterator __tmp = *this;
   121		_M_read();
   122		return __tmp;
   123	      }
   124	
   125	    private:
   126	      bool
   127	      _M_equal(const istream_iterator& __x) const
   128	      {
   129		// Ideally this would just return _M_stream == __x._M_stream,
   130		// but code compiled with old versions never sets _M_stream to null.
   131		return (_M_ok == __x._M_ok) && (!_M_ok || _M_stream == __x._M_stream);
   132	      }
   133	
   134	      void
   135	      _M_read()
   136	      {
   137	        if (_M_stream && !(*_M_stream >> _M_value))
   138	          {
   139	            _M_stream = 0;
   140	            _M_ok = false;
   141	          }
   142	      }
   143	
   144	      /// Return true if the iterators refer to the same stream,
   145	      /// or are both at end-of-stream.
   146	      friend bool
   147	      operator==(const istream_iterator& __x, const istream_iterator& __y)
   148	      { return __x._M_equal(__y); }
   149	
   150	      /// Return true if the iterators refer to different streams,
   151	      /// or if one is at end-of-stream and the other is not.
   152	      friend bool
   153	      operator!=(const istream_iterator& __x, const istream_iterator& __y)
   154	      { return !__x._M_equal(__y); }
   155	
   156	#if __cplusplus > 201703L && __cpp_lib_concepts
   157	      friend bool
   158	      operator==(const istream_iterator& __i, default_sentinel_t)
   159	      { return !__i._M_stream; }
   160	#endif
   161	    };
   162	
   163	  /**
   164	   *  @brief  Provides output iterator semantics for streams.
   165	   *
   166	   *  This class provides an iterator to write to an ostream.  The type Tp is
   167	   *  the only type written by this iterator and there must be an
   168	   *  operator<<(Tp) defined.
   169	   *
   170	   *  @tparam  _Tp  The type to write to the ostream.
   171	   *  @tparam  _CharT  The ostream char_type.
   172	   *  @tparam  _Traits  The ostream char_traits.
   173	  */
   174	  template<typename _Tp, typename _CharT = char,
   175	           typename _Traits = char_traits<_CharT> >
   176	    class ostream_iterator
   177	    : public iterator<output_iterator_tag, void, void, void, void>
   178	    {
   179	    public:
   180	      ///@{
   181	      /// Public typedef
   182	#if __cplusplus > 201703L
   183	      using difference_type = ptrdiff_t;
   184	#endif
   185	      typedef _CharT                         char_type;
   186	      typedef _Traits                        traits_type;
   187	      typedef basic_ostream<_CharT, _Traits> ostream_type;
   188	      ///@}
   189	
   190	    private:
   191	      ostream_type*	_M_stream;
   192	      const _CharT*	_M_string;
   193	
   194	    public:
   195	#if __cplusplus > 201703L
   196	      constexpr ostream_iterator() noexcept
   197	      : _M_stream(nullptr), _M_string(nullptr) { }
   198	#endif
   199	
   200	      /// Construct from an ostream.
   201	      ostream_iterator(ostream_type& __s)
   202	      : _M_stream(std::__addressof(__s)), _M_string(0) {}
   203	
   204	      /**
   205	       *  Construct from an ostream.
   206	       *
   207	       *  The delimiter string @a c is written to the stream after every Tp
   208	       *  written to the stream.  The delimiter is not copied, and thus must
   209	       *  not be destroyed while this iterator is in use.
   210	       *
   211	       *  @param  __s  Underlying ostream to write to.
   212	       *  @param  __c  CharT delimiter string to insert.
   213	      */
   214	      ostream_iterator(ostream_type& __s, const _CharT* __c)
   215	      : _M_stream(std::__addressof(__s)), _M_string(__c)  { }
   216	
   217	      /// Copy constructor.
   218	      ostream_iterator(const ostream_iterator& __obj)
   219	      : _M_stream(__obj._M_stream), _M_string(__obj._M_string)  { }
   220	
   221	#if __cplusplus >= 201103L
   222	      ostream_iterator& operator=(const ostream_iterator&) = default;
   223	#endif
   224	
   225	      /// Writes @a value to underlying ostream using operator<<.  If
   226	      /// constructed with delimiter string, writes delimiter to ostream.
   227	      ostream_iterator&
   228	      operator=(const _Tp& __value)
   229	      {
   230		__glibcxx_requires_cond(_M_stream != 0,
   231					_M_message(__gnu_debug::__msg_output_ostream)
   232					._M_iterator(*this));
   233		*_M_stream << __value;
   234		if (_M_string)
   235	          *_M_stream << _M_string;
   236		return *this;
   237	      }
   238	
   239	      ostream_iterator&
   240	      operator*()
   241	      { return *this; }
   242	
   243	      ostream_iterator&
   244	      operator++()
   245	      { return *this; }
   246	
   247	      ostream_iterator&
   248	      operator++(int)
   249	      { return *this; }
   250	    };
   251	
   252	  /// @} group iterators
   253	
   254	_GLIBCXX_END_NAMESPACE_VERSION
   255	} // namespace
   256	
   257	#endif