contrib/gcc-3.4/libstdc++-v3/include/bits/postypes.h

   1 // Position types -*- C++ -*-
   2
   3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2003, 2004
   4 // Free Software Foundation, Inc.
   5 //
   6 // This file is part of the GNU ISO C++ Library.  This library is free
   7 // software; you can redistribute it and/or modify it under the
   8 // terms of the GNU General Public License as published by the
   9 // Free Software Foundation; either version 2, or (at your option)
  10 // any later version.
  11
  12 // This library is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16
  17 // You should have received a copy of the GNU General Public License along
  18 // with this library; see the file COPYING.  If not, write to the Free
  19 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  20 // USA.
  21
  22 // As a special exception, you may use this file as part of a free software
  23 // library without restriction.  Specifically, if other files instantiate
  24 // templates or use macros or inline functions from this file, or you compile
  25 // this file and link it with other files to produce an executable, this
  26 // file does not by itself cause the resulting executable to be covered by
  27 // the GNU General Public License.  This exception does not however
  28 // invalidate any other reasons why the executable file might be covered by
  29 // the GNU General Public License.
  30
  31 //
  32 // ISO C++ 14882: 27.4.1 - Types
  33 // ISO C++ 14882: 27.4.3 - Template class fpos
  34 //
  35
  36 /** @file postypes.h
  37  *  This is an internal header file, included by other library headers.
  38  *  You should not attempt to use it directly.
  39  */
  40
  41 #ifndef _GLIBCXX_POSTYPES_H
  42 #define _GLIBCXX_POSTYPES_H 1
  43
  44 #pragma GCC system_header
  45
  46 #include <cwchar> // For mbstate_t
  47
  48 #ifdef _GLIBCXX_HAVE_STDINT_H
  49 #include <stdint.h> // For int64_t
  50 #endif
  51
  52 namespace std
  53 {
  54   // The types streamoff, streampos and wstreampos and the class
  55   // template fpos<> are described in clauses 21.1.2, 21.1.3, 27.1.2,
  56   // 27.2, 27.4.1, 27.4.3 and D.6. Despite all this verbage, the
  57   // behaviour of these types is mostly implementation defined or
  58   // unspecified. The behaviour in this implementation is as noted
  59   // below.
  60
  61   /**
  62    *  @brief  Type used by fpos, char_traits<char>, and char_traits<wchar_t>.
  63    *
  64    *  @if maint
  65    *  In clauses 21.1.3.1 and 27.4.1 streamoff is described as an
  66    *  implementation defined type.
  67    *  Note: In versions of GCC up to and including GCC 3.3, streamoff
  68    *  was typedef long.
  69    *  @endif
  70   */
  71 #ifdef _GLIBCXX_HAVE_INT64_T
  72   typedef int64_t       streamoff;
  73 #else
  74   typedef long long     streamoff;
  75 #endif
  76
  77   /// Integral type for I/O operation counts and buffer sizes.
  78   typedef ptrdiff_t     streamsize; // Signed integral type
  79
  80   template<typename _StateT>
  81     class fpos;
  82
  83   /**
  84    *  @brief  Class representing stream positions.
  85    *
  86    *  The standard places no requirements upon the template parameter StateT.
  87    *  In this implementation StateT must be DefaultConstructible,
  88    *  CopyConstructible and Assignable.  The standard only requires that fpos
  89    *  should contain a member of type StateT. In this implementation it also
  90    *  contains an offset stored as a signed integer.
  91    *
  92    *  @param  StateT  Type passed to and returned from state().
  93    */
  94   template<typename _StateT>
  95     class fpos
  96     {
  97     private:
  98       streamoff                 _M_off;
  99       _StateT                   _M_state;
 100
 101     public:
 102       // The standard doesn't require that fpos objects can be default
 103       // constructed. This implementation provides a default
 104       // constructor that initializes the offset to 0 and default
 105       // constructs the state.
 106       fpos()
 107       : _M_off(0), _M_state() { }
 108
 109       // The standard requires that fpos objects can be constructed
 110       // from streamoff objects using the constructor syntax, and
 111       // fails to give any meaningful semantics. In this
 112       // implementation implicit conversion is also allowed, and this
 113       // constructor stores the streamoff as the offset and default
 114       // constructs the state.
 115       /// Construct position from offset.
 116       fpos(streamoff __off)
 117       : _M_off(__off), _M_state() { }
 118
 119       /// Convert to streamoff.
 120       operator streamoff() const { return _M_off; }
 121
 122       /// Remember the value of @a st.
 123       void
 124       state(_StateT __st)
 125       { _M_state = __st; }
 126
 127       /// Return the last set value of @a st.
 128       _StateT
 129       state() const
 130       { return _M_state; }
 131
 132       // The standard only requires that operator== must be an
 133       // equivalence relation. In this implementation two fpos<StateT>
 134       // objects belong to the same equivalence class if the contained
 135       // offsets compare equal.
 136       /// Test if equivalent to another position.
 137       bool
 138       operator==(const fpos& __other) const
 139       { return _M_off == __other._M_off; }
 140
 141       /// Test if not equivalent to another position.
 142       bool
 143       operator!=(const fpos& __other) const
 144       { return _M_off != __other._M_off; }
 145
 146       // The standard requires that this operator must be defined, but
 147       // gives no semantics. In this implemenation it just adds it's
 148       // argument to the stored offset and returns *this.
 149       /// Add offset to this position.
 150       fpos&
 151       operator+=(streamoff __off)
 152       {
 153         _M_off += __off;
 154         return *this;
 155       }
 156
 157       // The standard requires that this operator must be defined, but
 158       // gives no semantics. In this implemenation it just subtracts
 159       // it's argument from the stored offset and returns *this.
 160       /// Subtract offset from this position.
 161       fpos&
 162       operator-=(streamoff __off)
 163       {
 164         _M_off -= __off;
 165         return *this;
 166       }
 167
 168       // The standard requires that this operator must be defined, but
 169       // defines it's semantics only in terms of operator-. In this
 170       // implementation it constructs a copy of *this, adds the
 171       // argument to that copy using operator+= and then returns the
 172       // copy.
 173       /// Add position and offset.
 174       fpos
 175       operator+(streamoff __off) const
 176       {
 177         fpos __pos(*this);
 178         __pos += __off;
 179         return __pos;
 180       }
 181
 182       // The standard requires that this operator must be defined, but
 183       // defines it's semantics only in terms of operator+. In this
 184       // implementation it constructs a copy of *this, subtracts the
 185       // argument from that copy using operator-= and then returns the
 186       // copy.
 187       /// Subtract offset from position.
 188       fpos
 189       operator-(streamoff __off) const
 190       {
 191         fpos __pos(*this);
 192         __pos -= __off;
 193         return __pos;
 194       }
 195
 196       // The standard requires that this operator must be defined, but
 197       // defines it's semantics only in terms of operator+. In this
 198       // implementation it returns the difference between the offset
 199       // stored in *this and in the argument.
 200       /// Subtract position to return offset.
 201       streamoff
 202       operator-(const fpos& __other) const
 203       { return _M_off - __other._M_off; }
 204     };
 205
 206   // Clauses 21.1.3.1 and 21.1.3.2 describe streampos and wstreampos
 207   // as implementation defined types, but clause 27.2 requires that
 208   // they must both be typedefs for fpos<mbstate_t>
 209   /// File position for char streams.
 210   typedef fpos<mbstate_t> streampos;
 211   /// File position for wchar_t streams.
 212   typedef fpos<mbstate_t> wstreampos;
 213 } // namespace std
 214
 215 #endif