libstdc++-v3/include/bits/stream_iterator.h

   1 // Stream iterators
   2
   3 // Copyright (C) 2001-2018 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       bool              _M_ok;
  61
  62     public:
  63       ///  Construct end of input stream iterator.
  64       _GLIBCXX_CONSTEXPR istream_iterator()
  65       : _M_stream(0), _M_value(), _M_ok(false) {}
  66
  67       ///  Construct start of input stream iterator.
  68       istream_iterator(istream_type& __s)
  69       : _M_stream(std::__addressof(__s))
  70       { _M_read(); }
  71
  72       istream_iterator(const istream_iterator& __obj)
  73       : _M_stream(__obj._M_stream), _M_value(__obj._M_value),
  74         _M_ok(__obj._M_ok)
  75       { }
  76
  77       const _Tp&
  78       operator*() const
  79       {
  80         __glibcxx_requires_cond(_M_ok,
  81                                 _M_message(__gnu_debug::__msg_deref_istream)
  82                                 ._M_iterator(*this));
  83         return _M_value;
  84       }
  85
  86       const _Tp*
  87       operator->() const { return std::__addressof((operator*())); }
  88
  89       istream_iterator&
  90       operator++()
  91       {
  92         __glibcxx_requires_cond(_M_ok,
  93                                 _M_message(__gnu_debug::__msg_inc_istream)
  94                                 ._M_iterator(*this));
  95         _M_read();
  96         return *this;
  97       }
  98
  99       istream_iterator
 100       operator++(int)
 101       {
 102         __glibcxx_requires_cond(_M_ok,
 103                                 _M_message(__gnu_debug::__msg_inc_istream)
 104                                 ._M_iterator(*this));
 105         istream_iterator __tmp = *this;
 106         _M_read();
 107         return __tmp;
 108       }
 109
 110       bool
 111       _M_equal(const istream_iterator& __x) const
 112       { return (_M_ok == __x._M_ok) && (!_M_ok || _M_stream == __x._M_stream); }
 113
 114     private:
 115       void
 116       _M_read()
 117       {
 118         _M_ok = (_M_stream && *_M_stream) ? true : false;
 119         if (_M_ok)
 120           {
 121             *_M_stream >> _M_value;
 122             _M_ok = *_M_stream ? true : false;
 123           }
 124       }
 125     };
 126
 127   ///  Return true if x and y are both end or not end, or x and y are the same.
 128   template<typename _Tp, typename _CharT, typename _Traits, typename _Dist>
 129     inline bool
 130     operator==(const istream_iterator<_Tp, _CharT, _Traits, _Dist>& __x,
 131                const istream_iterator<_Tp, _CharT, _Traits, _Dist>& __y)
 132     { return __x._M_equal(__y); }
 133
 134   ///  Return false if x and y are both end or not end, or x and y are the same.
 135   template <class _Tp, class _CharT, class _Traits, class _Dist>
 136     inline bool
 137     operator!=(const istream_iterator<_Tp, _CharT, _Traits, _Dist>& __x,
 138                const istream_iterator<_Tp, _CharT, _Traits, _Dist>& __y)
 139     { return !__x._M_equal(__y); }
 140
 141   /**
 142    *  @brief  Provides output iterator semantics for streams.
 143    *
 144    *  This class provides an iterator to write to an ostream.  The type Tp is
 145    *  the only type written by this iterator and there must be an
 146    *  operator<<(Tp) defined.
 147    *
 148    *  @tparam  _Tp  The type to write to the ostream.
 149    *  @tparam  _CharT  The ostream char_type.
 150    *  @tparam  _Traits  The ostream char_traits.
 151   */
 152   template<typename _Tp, typename _CharT = char,
 153            typename _Traits = char_traits<_CharT> >
 154     class ostream_iterator
 155     : public iterator<output_iterator_tag, void, void, void, void>
 156     {
 157     public:
 158       //@{
 159       /// Public typedef
 160       typedef _CharT                         char_type;
 161       typedef _Traits                        traits_type;
 162       typedef basic_ostream<_CharT, _Traits> ostream_type;
 163       //@}
 164
 165     private:
 166       ostream_type*     _M_stream;
 167       const _CharT*     _M_string;
 168
 169     public:
 170       /// Construct from an ostream.
 171       ostream_iterator(ostream_type& __s)
 172       : _M_stream(std::__addressof(__s)), _M_string(0) {}
 173
 174       /**
 175        *  Construct from an ostream.
 176        *
 177        *  The delimiter string @a c is written to the stream after every Tp
 178        *  written to the stream.  The delimiter is not copied, and thus must
 179        *  not be destroyed while this iterator is in use.
 180        *
 181        *  @param  __s  Underlying ostream to write to.
 182        *  @param  __c  CharT delimiter string to insert.
 183       */
 184       ostream_iterator(ostream_type& __s, const _CharT* __c)
 185       : _M_stream(&__s), _M_string(__c)  { }
 186
 187       /// Copy constructor.
 188       ostream_iterator(const ostream_iterator& __obj)
 189       : _M_stream(__obj._M_stream), _M_string(__obj._M_string)  { }
 190
 191       /// Writes @a value to underlying ostream using operator<<.  If
 192       /// constructed with delimiter string, writes delimiter to ostream.
 193       ostream_iterator&
 194       operator=(const _Tp& __value)
 195       {
 196         __glibcxx_requires_cond(_M_stream != 0,
 197                                 _M_message(__gnu_debug::__msg_output_ostream)
 198                                 ._M_iterator(*this));
 199         *_M_stream << __value;
 200         if (_M_string) *_M_stream << _M_string;
 201         return *this;
 202       }
 203
 204       ostream_iterator&
 205       operator*()
 206       { return *this; }
 207
 208       ostream_iterator&
 209       operator++()
 210       { return *this; }
 211
 212       ostream_iterator&
 213       operator++(int)
 214       { return *this; }
 215     };
 216
 217   // @} group iterators
 218
 219 _GLIBCXX_END_NAMESPACE_VERSION
 220 } // namespace
 221
 222 #endif