stream_iterator.h

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00001 // Stream iterators
00002 
00003 // Copyright (C) 2001, 2004, 2005, 2009 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /** @file stream_iterator.h
00026  *  This is an internal header file, included by other library headers.
00027  *  You should not attempt to use it directly.
00028  */
00029 
00030 #ifndef _STREAM_ITERATOR_H
00031 #define _STREAM_ITERATOR_H 1
00032 
00033 #pragma GCC system_header
00034 
00035 #include <debug/debug.h>
00036 
00037 _GLIBCXX_BEGIN_NAMESPACE(std)
00038 
00039   /// Provides input iterator semantics for streams.
00040   template<typename _Tp, typename _CharT = char,
00041            typename _Traits = char_traits<_CharT>, typename _Dist = ptrdiff_t>
00042     class istream_iterator
00043     : public iterator<input_iterator_tag, _Tp, _Dist, const _Tp*, const _Tp&>
00044     {
00045     public:
00046       typedef _CharT                         char_type;
00047       typedef _Traits                        traits_type;
00048       typedef basic_istream<_CharT, _Traits> istream_type;
00049 
00050     private:
00051       istream_type* _M_stream;
00052       _Tp       _M_value;
00053       bool      _M_ok;
00054 
00055     public:
00056       ///  Construct end of input stream iterator.
00057       istream_iterator()
00058       : _M_stream(0), _M_value(), _M_ok(false) {}
00059 
00060       ///  Construct start of input stream iterator.
00061       istream_iterator(istream_type& __s)
00062       : _M_stream(&__s)
00063       { _M_read(); }
00064 
00065       istream_iterator(const istream_iterator& __obj)
00066       : _M_stream(__obj._M_stream), _M_value(__obj._M_value),
00067         _M_ok(__obj._M_ok)
00068       { }
00069 
00070       const _Tp&
00071       operator*() const
00072       {
00073     __glibcxx_requires_cond(_M_ok,
00074                 _M_message(__gnu_debug::__msg_deref_istream)
00075                 ._M_iterator(*this));
00076     return _M_value;
00077       }
00078 
00079       const _Tp*
00080       operator->() const { return &(operator*()); }
00081 
00082       istream_iterator&
00083       operator++()
00084       {
00085     __glibcxx_requires_cond(_M_ok,
00086                 _M_message(__gnu_debug::__msg_inc_istream)
00087                 ._M_iterator(*this));
00088     _M_read();
00089     return *this;
00090       }
00091 
00092       istream_iterator
00093       operator++(int)
00094       {
00095     __glibcxx_requires_cond(_M_ok,
00096                 _M_message(__gnu_debug::__msg_inc_istream)
00097                 ._M_iterator(*this));
00098     istream_iterator __tmp = *this;
00099     _M_read();
00100     return __tmp;
00101       }
00102 
00103       bool
00104       _M_equal(const istream_iterator& __x) const
00105       { return (_M_ok == __x._M_ok) && (!_M_ok || _M_stream == __x._M_stream); }
00106 
00107     private:
00108       void
00109       _M_read()
00110       {
00111     _M_ok = (_M_stream && *_M_stream) ? true : false;
00112     if (_M_ok)
00113       {
00114         *_M_stream >> _M_value;
00115         _M_ok = *_M_stream ? true : false;
00116       }
00117       }
00118     };
00119 
00120   ///  Return true if x and y are both end or not end, or x and y are the same.
00121   template<typename _Tp, typename _CharT, typename _Traits, typename _Dist>
00122     inline bool
00123     operator==(const istream_iterator<_Tp, _CharT, _Traits, _Dist>& __x,
00124            const istream_iterator<_Tp, _CharT, _Traits, _Dist>& __y)
00125     { return __x._M_equal(__y); }
00126 
00127   ///  Return false if x and y are both end or not end, or x and y are the same.
00128   template <class _Tp, class _CharT, class _Traits, class _Dist>
00129     inline bool
00130     operator!=(const istream_iterator<_Tp, _CharT, _Traits, _Dist>& __x,
00131            const istream_iterator<_Tp, _CharT, _Traits, _Dist>& __y)
00132     { return !__x._M_equal(__y); }
00133 
00134   /**
00135    *  @brief  Provides output iterator semantics for streams.
00136    *
00137    *  This class provides an iterator to write to an ostream.  The type Tp is
00138    *  the only type written by this iterator and there must be an
00139    *  operator<<(Tp) defined.
00140    *
00141    *  @param  Tp  The type to write to the ostream.
00142    *  @param  CharT  The ostream char_type.
00143    *  @param  Traits  The ostream char_traits.
00144   */
00145   template<typename _Tp, typename _CharT = char,
00146            typename _Traits = char_traits<_CharT> >
00147     class ostream_iterator
00148     : public iterator<output_iterator_tag, void, void, void, void>
00149     {
00150     public:
00151       //@{
00152       /// Public typedef
00153       typedef _CharT                         char_type;
00154       typedef _Traits                        traits_type;
00155       typedef basic_ostream<_CharT, _Traits> ostream_type;
00156       //@}
00157 
00158     private:
00159       ostream_type* _M_stream;
00160       const _CharT* _M_string;
00161 
00162     public:
00163       /// Construct from an ostream.
00164       ostream_iterator(ostream_type& __s) : _M_stream(&__s), _M_string(0) {}
00165 
00166       /**
00167        *  Construct from an ostream.
00168        *
00169        *  The delimiter string @a c is written to the stream after every Tp
00170        *  written to the stream.  The delimiter is not copied, and thus must
00171        *  not be destroyed while this iterator is in use.
00172        *
00173        *  @param  s  Underlying ostream to write to.
00174        *  @param  c  CharT delimiter string to insert.
00175       */
00176       ostream_iterator(ostream_type& __s, const _CharT* __c)
00177       : _M_stream(&__s), _M_string(__c)  { }
00178 
00179       /// Copy constructor.
00180       ostream_iterator(const ostream_iterator& __obj)
00181       : _M_stream(__obj._M_stream), _M_string(__obj._M_string)  { }
00182 
00183       /// Writes @a value to underlying ostream using operator<<.  If
00184       /// constructed with delimiter string, writes delimiter to ostream.
00185       ostream_iterator&
00186       operator=(const _Tp& __value)
00187       {
00188     __glibcxx_requires_cond(_M_stream != 0,
00189                 _M_message(__gnu_debug::__msg_output_ostream)
00190                 ._M_iterator(*this));
00191     *_M_stream << __value;
00192     if (_M_string) *_M_stream << _M_string;
00193     return *this;
00194       }
00195 
00196       ostream_iterator&
00197       operator*()
00198       { return *this; }
00199 
00200       ostream_iterator&
00201       operator++()
00202       { return *this; }
00203 
00204       ostream_iterator&
00205       operator++(int)
00206       { return *this; }
00207     };
00208 
00209 _GLIBCXX_END_NAMESPACE
00210 
00211 #endif

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