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

   1 // Position types -*- C++ -*-
   2
   3 // Copyright (C) 1997-2018 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/postypes.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{iosfwd}
  28  */
  29
  30 //
  31 // ISO C++ 14882: 27.4.1 - Types
  32 // ISO C++ 14882: 27.4.3 - Template class fpos
  33 //
  34
  35 #ifndef _GLIBCXX_POSTYPES_H
  36 #define _GLIBCXX_POSTYPES_H 1
  37
  38 #pragma GCC system_header
  39
  40 #include <cwchar> // For mbstate_t
  41
  42 // XXX If <stdint.h> is really needed, make sure to define the macros
  43 // before including it, in order not to break <tr1/cstdint> (and <cstdint>
  44 // in C++11).  Reconsider all this as soon as possible...
  45 #if (defined(_GLIBCXX_HAVE_INT64_T) && !defined(_GLIBCXX_HAVE_INT64_T_LONG) \
  46      && !defined(_GLIBCXX_HAVE_INT64_T_LONG_LONG))
  47
  48 #ifndef __STDC_LIMIT_MACROS
  49 # define _UNDEF__STDC_LIMIT_MACROS
  50 # define __STDC_LIMIT_MACROS
  51 #endif
  52 #ifndef __STDC_CONSTANT_MACROS
  53 # define _UNDEF__STDC_CONSTANT_MACROS
  54 # define __STDC_CONSTANT_MACROS
  55 #endif
  56 #include <stdint.h> // For int64_t
  57 #ifdef _UNDEF__STDC_LIMIT_MACROS
  58 # undef __STDC_LIMIT_MACROS
  59 # undef _UNDEF__STDC_LIMIT_MACROS
  60 #endif
  61 #ifdef _UNDEF__STDC_CONSTANT_MACROS
  62 # undef __STDC_CONSTANT_MACROS
  63 # undef _UNDEF__STDC_CONSTANT_MACROS
  64 #endif
  65
  66 #endif
  67
  68 namespace std _GLIBCXX_VISIBILITY(default)
  69 {
  70 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  71
  72   // The types streamoff, streampos and wstreampos and the class
  73   // template fpos<> are described in clauses 21.1.2, 21.1.3, 27.1.2,
  74   // 27.2, 27.4.1, 27.4.3 and D.6. Despite all this verbiage, the
  75   // behaviour of these types is mostly implementation defined or
  76   // unspecified. The behaviour in this implementation is as noted
  77   // below.
  78
  79   /**
  80    *  @brief  Type used by fpos, char_traits<char>, and char_traits<wchar_t>.
  81    *
  82    *  In clauses 21.1.3.1 and 27.4.1 streamoff is described as an
  83    *  implementation defined type.
  84    *  Note: In versions of GCC up to and including GCC 3.3, streamoff
  85    *  was typedef long.
  86   */
  87 #ifdef _GLIBCXX_HAVE_INT64_T_LONG
  88   typedef long          streamoff;
  89 #elif defined(_GLIBCXX_HAVE_INT64_T_LONG_LONG)
  90   typedef long long     streamoff;
  91 #elif defined(_GLIBCXX_HAVE_INT64_T)
  92   typedef int64_t       streamoff;
  93 #else
  94   typedef long long     streamoff;
  95 #endif
  96
  97   /// Integral type for I/O operation counts and buffer sizes.
  98   typedef ptrdiff_t     streamsize; // Signed integral type
  99
 100   /**
 101    *  @brief  Class representing stream positions.
 102    *
 103    *  The standard places no requirements upon the template parameter StateT.
 104    *  In this implementation StateT must be DefaultConstructible,
 105    *  CopyConstructible and Assignable.  The standard only requires that fpos
 106    *  should contain a member of type StateT. In this implementation it also
 107    *  contains an offset stored as a signed integer.
 108    *
 109    *  @param  StateT  Type passed to and returned from state().
 110    */
 111   template<typename _StateT>
 112     class fpos
 113     {
 114     private:
 115       streamoff                 _M_off;
 116       _StateT                   _M_state;
 117
 118     public:
 119       // The standard doesn't require that fpos objects can be default
 120       // constructed. This implementation provides a default
 121       // constructor that initializes the offset to 0 and default
 122       // constructs the state.
 123       fpos()
 124       : _M_off(0), _M_state() { }
 125
 126       // The standard requires that fpos objects can be constructed
 127       // from streamoff objects using the constructor syntax, and
 128       // fails to give any meaningful semantics. In this
 129       // implementation implicit conversion is also allowed, and this
 130       // constructor stores the streamoff as the offset and default
 131       // constructs the state.
 132       /// Construct position from offset.
 133       fpos(streamoff __off)
 134       : _M_off(__off), _M_state() { }
 135
 136 #if __cplusplus >= 201103L
 137       fpos(const fpos&) = default;
 138       fpos& operator=(const fpos&) = default;
 139       ~fpos() = default;
 140 #endif
 141
 142       /// Convert to streamoff.
 143       operator streamoff() const { return _M_off; }
 144
 145       /// Remember the value of @a st.
 146       void
 147       state(_StateT __st)
 148       { _M_state = __st; }
 149
 150       /// Return the last set value of @a st.
 151       _StateT
 152       state() const
 153       { return _M_state; }
 154
 155       // The standard requires that this operator must be defined, but
 156       // gives no semantics. In this implementation it just adds its
 157       // argument to the stored offset and returns *this.
 158       /// Add offset to this position.
 159       fpos&
 160       operator+=(streamoff __off)
 161       {
 162         _M_off += __off;
 163         return *this;
 164       }
 165
 166       // The standard requires that this operator must be defined, but
 167       // gives no semantics. In this implementation it just subtracts
 168       // its argument from the stored offset and returns *this.
 169       /// Subtract offset from this position.
 170       fpos&
 171       operator-=(streamoff __off)
 172       {
 173         _M_off -= __off;
 174         return *this;
 175       }
 176
 177       // The standard requires that this operator must be defined, but
 178       // defines its semantics only in terms of operator-. In this
 179       // implementation it constructs a copy of *this, adds the
 180       // argument to that copy using operator+= and then returns the
 181       // copy.
 182       /// Add position and offset.
 183       fpos
 184       operator+(streamoff __off) const
 185       {
 186         fpos __pos(*this);
 187         __pos += __off;
 188         return __pos;
 189       }
 190
 191       // The standard requires that this operator must be defined, but
 192       // defines its semantics only in terms of operator+. In this
 193       // implementation it constructs a copy of *this, subtracts the
 194       // argument from that copy using operator-= and then returns the
 195       // copy.
 196       /// Subtract offset from position.
 197       fpos
 198       operator-(streamoff __off) const
 199       {
 200         fpos __pos(*this);
 201         __pos -= __off;
 202         return __pos;
 203       }
 204
 205       // The standard requires that this operator must be defined, but
 206       // defines its semantics only in terms of operator+. In this
 207       // implementation it returns the difference between the offset
 208       // stored in *this and in the argument.
 209       /// Subtract position to return offset.
 210       streamoff
 211       operator-(const fpos& __other) const
 212       { return _M_off - __other._M_off; }
 213     };
 214
 215   // The standard only requires that operator== must be an
 216   // equivalence relation. In this implementation two fpos<StateT>
 217   // objects belong to the same equivalence class if the contained
 218   // offsets compare equal.
 219   /// Test if equivalent to another position.
 220   template<typename _StateT>
 221     inline bool
 222     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
 223     { return streamoff(__lhs) == streamoff(__rhs); }
 224
 225   template<typename _StateT>
 226     inline bool
 227     operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
 228     { return streamoff(__lhs) != streamoff(__rhs); }
 229
 230   // Clauses 21.1.3.1 and 21.1.3.2 describe streampos and wstreampos
 231   // as implementation defined types, but clause 27.2 requires that
 232   // they must both be typedefs for fpos<mbstate_t>
 233   /// File position for char streams.
 234   typedef fpos<mbstate_t> streampos;
 235   /// File position for wchar_t streams.
 236   typedef fpos<mbstate_t> wstreampos;
 237
 238 #if __cplusplus >= 201103L
 239   /// File position for char16_t streams.
 240   typedef fpos<mbstate_t> u16streampos;
 241   /// File position for char32_t streams.
 242   typedef fpos<mbstate_t> u32streampos;
 243 #endif
 244
 245 _GLIBCXX_END_NAMESPACE_VERSION
 246 } // namespace
 247
 248 #endif