libstdc++
postypes.h
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1 // Position types -*- C++ -*-
2 
3 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
4 // 2006, 2007, 2008, 2009, 2010
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 3, 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 // Under Section 7 of GPL version 3, you are granted additional
19 // permissions described in the GCC Runtime Library Exception, version
20 // 3.1, as published by the Free Software Foundation.
21 
22 // You should have received a copy of the GNU General Public License and
23 // a copy of the GCC Runtime Library Exception along with this program;
24 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
25 // <http://www.gnu.org/licenses/>.
26 
27 /** @file bits/postypes.h
28  * This is an internal header file, included by other library headers.
29  * Do not attempt to use it directly. @headername{iosfwd}
30  */
31 
32 //
33 // ISO C++ 14882: 27.4.1 - Types
34 // ISO C++ 14882: 27.4.3 - Template class fpos
35 //
36 
37 #ifndef _GLIBCXX_POSTYPES_H
38 #define _GLIBCXX_POSTYPES_H 1
39 
40 #pragma GCC system_header
41 
42 #include <cwchar> // For mbstate_t
43 
44 // XXX If <stdint.h> is really needed, make sure to define the macros
45 // before including it, in order not to break <tr1/cstdint> (and <cstdint>
46 // in C++0x). Reconsider all this as soon as possible...
47 #if (defined(_GLIBCXX_HAVE_INT64_T) && !defined(_GLIBCXX_HAVE_INT64_T_LONG) \
48  && !defined(_GLIBCXX_HAVE_INT64_T_LONG_LONG))
49 
50 #ifndef __STDC_LIMIT_MACROS
51 # define _UNDEF__STDC_LIMIT_MACROS
52 # define __STDC_LIMIT_MACROS
53 #endif
54 #ifndef __STDC_CONSTANT_MACROS
55 # define _UNDEF__STDC_CONSTANT_MACROS
56 # define __STDC_CONSTANT_MACROS
57 #endif
58 #include <stdint.h> // For int64_t
59 #ifdef _UNDEF__STDC_LIMIT_MACROS
60 # undef __STDC_LIMIT_MACROS
61 # undef _UNDEF__STDC_LIMIT_MACROS
62 #endif
63 #ifdef _UNDEF__STDC_CONSTANT_MACROS
64 # undef __STDC_CONSTANT_MACROS
65 # undef _UNDEF__STDC_CONSTANT_MACROS
66 #endif
67 
68 #endif
69 
70 namespace std _GLIBCXX_VISIBILITY(default)
71 {
72 _GLIBCXX_BEGIN_NAMESPACE_VERSION
73 
74  // The types streamoff, streampos and wstreampos and the class
75  // template fpos<> are described in clauses 21.1.2, 21.1.3, 27.1.2,
76  // 27.2, 27.4.1, 27.4.3 and D.6. Despite all this verbiage, the
77  // behaviour of these types is mostly implementation defined or
78  // unspecified. The behaviour in this implementation is as noted
79  // below.
80 
81  /**
82  * @brief Type used by fpos, char_traits<char>, and char_traits<wchar_t>.
83  *
84  * In clauses 21.1.3.1 and 27.4.1 streamoff is described as an
85  * implementation defined type.
86  * Note: In versions of GCC up to and including GCC 3.3, streamoff
87  * was typedef long.
88  */
89 #ifdef _GLIBCXX_HAVE_INT64_T_LONG
90  typedef long streamoff;
91 #elif defined(_GLIBCXX_HAVE_INT64_T_LONG_LONG)
92  typedef long long streamoff;
93 #elif defined(_GLIBCXX_HAVE_INT64_T)
94  typedef int64_t streamoff;
95 #else
96  typedef long long streamoff;
97 #endif
98 
99  /// Integral type for I/O operation counts and buffer sizes.
100  typedef ptrdiff_t streamsize; // Signed integral type
101 
102  /**
103  * @brief Class representing stream positions.
104  *
105  * The standard places no requirements upon the template parameter StateT.
106  * In this implementation StateT must be DefaultConstructible,
107  * CopyConstructible and Assignable. The standard only requires that fpos
108  * should contain a member of type StateT. In this implementation it also
109  * contains an offset stored as a signed integer.
110  *
111  * @param StateT Type passed to and returned from state().
112  */
113  template<typename _StateT>
114  class fpos
115  {
116  private:
117  streamoff _M_off;
118  _StateT _M_state;
119 
120  public:
121  // The standard doesn't require that fpos objects can be default
122  // constructed. This implementation provides a default
123  // constructor that initializes the offset to 0 and default
124  // constructs the state.
125  fpos()
126  : _M_off(0), _M_state() { }
127 
128  // The standard requires that fpos objects can be constructed
129  // from streamoff objects using the constructor syntax, and
130  // fails to give any meaningful semantics. In this
131  // implementation implicit conversion is also allowed, and this
132  // constructor stores the streamoff as the offset and default
133  // constructs the state.
134  /// Construct position from offset.
136  : _M_off(__off), _M_state() { }
137 
138  /// Convert to streamoff.
139  operator streamoff() const { return _M_off; }
140 
141  /// Remember the value of @a st.
142  void
143  state(_StateT __st)
144  { _M_state = __st; }
145 
146  /// Return the last set value of @a st.
147  _StateT
148  state() const
149  { return _M_state; }
150 
151  // The standard requires that this operator must be defined, but
152  // gives no semantics. In this implementation it just adds its
153  // argument to the stored offset and returns *this.
154  /// Add offset to this position.
155  fpos&
157  {
158  _M_off += __off;
159  return *this;
160  }
161 
162  // The standard requires that this operator must be defined, but
163  // gives no semantics. In this implementation it just subtracts
164  // its argument from the stored offset and returns *this.
165  /// Subtract offset from this position.
166  fpos&
168  {
169  _M_off -= __off;
170  return *this;
171  }
172 
173  // The standard requires that this operator must be defined, but
174  // defines its semantics only in terms of operator-. In this
175  // implementation it constructs a copy of *this, adds the
176  // argument to that copy using operator+= and then returns the
177  // copy.
178  /// Add position and offset.
179  fpos
180  operator+(streamoff __off) const
181  {
182  fpos __pos(*this);
183  __pos += __off;
184  return __pos;
185  }
186 
187  // The standard requires that this operator must be defined, but
188  // defines its semantics only in terms of operator+. In this
189  // implementation it constructs a copy of *this, subtracts the
190  // argument from that copy using operator-= and then returns the
191  // copy.
192  /// Subtract offset from position.
193  fpos
194  operator-(streamoff __off) const
195  {
196  fpos __pos(*this);
197  __pos -= __off;
198  return __pos;
199  }
200 
201  // The standard requires that this operator must be defined, but
202  // defines its semantics only in terms of operator+. In this
203  // implementation it returns the difference between the offset
204  // stored in *this and in the argument.
205  /// Subtract position to return offset.
206  streamoff
207  operator-(const fpos& __other) const
208  { return _M_off - __other._M_off; }
209  };
210 
211  // The standard only requires that operator== must be an
212  // equivalence relation. In this implementation two fpos<StateT>
213  // objects belong to the same equivalence class if the contained
214  // offsets compare equal.
215  /// Test if equivalent to another position.
216  template<typename _StateT>
217  inline bool
218  operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
219  { return streamoff(__lhs) == streamoff(__rhs); }
220 
221  template<typename _StateT>
222  inline bool
223  operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
224  { return streamoff(__lhs) != streamoff(__rhs); }
225 
226  // Clauses 21.1.3.1 and 21.1.3.2 describe streampos and wstreampos
227  // as implementation defined types, but clause 27.2 requires that
228  // they must both be typedefs for fpos<mbstate_t>
229  /// File position for char streams.
231  /// File position for wchar_t streams.
233 
234 #ifdef __GXX_EXPERIMENTAL_CXX0X__
235  /// File position for char16_t streams.
237  /// File position for char32_t streams.
239 #endif
240 
241 _GLIBCXX_END_NAMESPACE_VERSION
242 } // namespace
243 
244 #endif