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

   1 // Position types -*- C++ -*-
   2
   3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   4 // 2006, 2007, 2008
   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 2, 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 // You should have received a copy of the GNU General Public License along
  19 // with this library; see the file COPYING.  If not, write to the Free
  20 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  21 // USA.
  22
  23 // As a special exception, you may use this file as part of a free software
  24 // library without restriction.  Specifically, if other files instantiate
  25 // templates or use macros or inline functions from this file, or you compile
  26 // this file and link it with other files to produce an executable, this
  27 // file does not by itself cause the resulting executable to be covered by
  28 // the GNU General Public License.  This exception does not however
  29 // invalidate any other reasons why the executable file might be covered by
  30 // the GNU General Public License.
  31
  32 /** @file postypes.h
  33  *  This is an internal header file, included by other library headers.
  34  *  You should not attempt to use it directly.
  35  */
  36
  37 //
  38 // ISO C++ 14882: 27.4.1 - Types
  39 // ISO C++ 14882: 27.4.3 - Template class fpos
  40 //
  41
  42 #ifndef _GLIBCXX_POSTYPES_H
  43 #define _GLIBCXX_POSTYPES_H 1
  44
  45 #pragma GCC system_header
  46
  47 #include <cwchar> // For mbstate_t
  48
  49 #ifdef _GLIBCXX_HAVE_STDINT_H
  50 #include <stdint.h> // For int64_t
  51 #endif
  52
  53 _GLIBCXX_BEGIN_NAMESPACE(std)
  54
  55   // The types streamoff, streampos and wstreampos and the class
  56   // template fpos<> are described in clauses 21.1.2, 21.1.3, 27.1.2,
  57   // 27.2, 27.4.1, 27.4.3 and D.6. Despite all this verbiage, the
  58   // behaviour of these types is mostly implementation defined or
  59   // unspecified. The behaviour in this implementation is as noted
  60   // below.
  61
  62   /**
  63    *  @brief  Type used by fpos, char_traits<char>, and char_traits<wchar_t>.
  64    *
  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   */
  70 #ifdef _GLIBCXX_HAVE_INT64_T
  71   typedef int64_t       streamoff;
  72 #else
  73   typedef long long     streamoff;
  74 #endif
  75
  76   /// Integral type for I/O operation counts and buffer sizes.
  77   typedef ptrdiff_t     streamsize; // Signed integral type
  78
  79   /**
  80    *  @brief  Class representing stream positions.
  81    *
  82    *  The standard places no requirements upon the template parameter StateT.
  83    *  In this implementation StateT must be DefaultConstructible,
  84    *  CopyConstructible and Assignable.  The standard only requires that fpos
  85    *  should contain a member of type StateT. In this implementation it also
  86    *  contains an offset stored as a signed integer.
  87    *
  88    *  @param  StateT  Type passed to and returned from state().
  89    */
  90   template<typename _StateT>
  91     class fpos
  92     {
  93     private:
  94       streamoff                 _M_off;
  95       _StateT                   _M_state;
  96
  97     public:
  98       // The standard doesn't require that fpos objects can be default
  99       // constructed. This implementation provides a default
 100       // constructor that initializes the offset to 0 and default
 101       // constructs the state.
 102       fpos()
 103       : _M_off(0), _M_state() { }
 104
 105       // The standard requires that fpos objects can be constructed
 106       // from streamoff objects using the constructor syntax, and
 107       // fails to give any meaningful semantics. In this
 108       // implementation implicit conversion is also allowed, and this
 109       // constructor stores the streamoff as the offset and default
 110       // constructs the state.
 111       /// Construct position from offset.
 112       fpos(streamoff __off)
 113       : _M_off(__off), _M_state() { }
 114
 115       /// Convert to streamoff.
 116       operator streamoff() const { return _M_off; }
 117
 118       /// Remember the value of @a st.
 119       void
 120       state(_StateT __st)
 121       { _M_state = __st; }
 122
 123       /// Return the last set value of @a st.
 124       _StateT
 125       state() const
 126       { return _M_state; }
 127
 128       // The standard requires that this operator must be defined, but
 129       // gives no semantics. In this implementation it just adds its
 130       // argument to the stored offset and returns *this.
 131       /// Add offset to this position.
 132       fpos&
 133       operator+=(streamoff __off)
 134       {
 135         _M_off += __off;
 136         return *this;
 137       }
 138
 139       // The standard requires that this operator must be defined, but
 140       // gives no semantics. In this implementation it just subtracts
 141       // its argument from the stored offset and returns *this.
 142       /// Subtract offset from this position.
 143       fpos&
 144       operator-=(streamoff __off)
 145       {
 146         _M_off -= __off;
 147         return *this;
 148       }
 149
 150       // The standard requires that this operator must be defined, but
 151       // defines its semantics only in terms of operator-. In this
 152       // implementation it constructs a copy of *this, adds the
 153       // argument to that copy using operator+= and then returns the
 154       // copy.
 155       /// Add position and offset.
 156       fpos
 157       operator+(streamoff __off) const
 158       {
 159         fpos __pos(*this);
 160         __pos += __off;
 161         return __pos;
 162       }
 163
 164       // The standard requires that this operator must be defined, but
 165       // defines its semantics only in terms of operator+. In this
 166       // implementation it constructs a copy of *this, subtracts the
 167       // argument from that copy using operator-= and then returns the
 168       // copy.
 169       /// Subtract offset from position.
 170       fpos
 171       operator-(streamoff __off) const
 172       {
 173         fpos __pos(*this);
 174         __pos -= __off;
 175         return __pos;
 176       }
 177
 178       // The standard requires that this operator must be defined, but
 179       // defines its semantics only in terms of operator+. In this
 180       // implementation it returns the difference between the offset
 181       // stored in *this and in the argument.
 182       /// Subtract position to return offset.
 183       streamoff
 184       operator-(const fpos& __other) const
 185       { return _M_off - __other._M_off; }
 186     };
 187
 188   // The standard only requires that operator== must be an
 189   // equivalence relation. In this implementation two fpos<StateT>
 190   // objects belong to the same equivalence class if the contained
 191   // offsets compare equal.
 192   /// Test if equivalent to another position.
 193   template<typename _StateT>
 194     inline bool
 195     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
 196     { return streamoff(__lhs) == streamoff(__rhs); }
 197
 198   template<typename _StateT>
 199     inline bool
 200     operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
 201     { return streamoff(__lhs) != streamoff(__rhs); }
 202
 203   // Clauses 21.1.3.1 and 21.1.3.2 describe streampos and wstreampos
 204   // as implementation defined types, but clause 27.2 requires that
 205   // they must both be typedefs for fpos<mbstate_t>
 206   /// File position for char streams.
 207   typedef fpos<mbstate_t> streampos;
 208   /// File position for wchar_t streams.
 209   typedef fpos<mbstate_t> wstreampos;
 210
 211 _GLIBCXX_END_NAMESPACE
 212
 213 #endif