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 0 : fpos(streamoff __off)
113 0 : : _M_off(__off), _M_state() { }
114 :
115 : /// Convert to streamoff.
116 0 : 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
|
