1// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
2// (C) Copyright 2003-2007 Jonathan Turkanis
3// Distributed under the Boost Software License, Version 1.0. (See accompanying
4// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
5
6// See http://www.boost.org/libs/iostreams for documentation.
7
8// Thanks to Gareth Sylvester-Bradley for the Dinkumware versions of the
9// positioning functions.
10
11#ifndef BOOST_IOSTREAMS_POSITIONING_HPP_INCLUDED
12#define BOOST_IOSTREAMS_POSITIONING_HPP_INCLUDED
13
14#if defined(_MSC_VER) && (_MSC_VER >= 1020)
15# pragma once
16#endif
17
18#include <boost/config.hpp>
19#include <boost/cstdint.hpp>
20#include <boost/integer_traits.hpp>
21#include <boost/iostreams/detail/config/codecvt.hpp> // mbstate_t.
22#include <boost/iostreams/detail/config/fpos.hpp>
23#include <boost/iostreams/detail/ios.hpp> // streamoff, streampos.
24
25// Must come last.
26#include <boost/iostreams/detail/config/disable_warnings.hpp>
27
28#ifdef BOOST_NO_STDC_NAMESPACE
29namespace std { using ::fpos_t; }
30#endif
31
32namespace boost { namespace iostreams {
33
34//------------------Definition of stream_offset-------------------------------//
35
36typedef boost::intmax_t stream_offset;
37
38//------------------Definition of stream_offset_to_streamoff------------------//
39
40inline std::streamoff stream_offset_to_streamoff(stream_offset off)
41{ return static_cast<stream_offset>(off); }
42
43//------------------Definition of offset_to_position--------------------------//
44
45# ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
46
47inline std::streampos offset_to_position(stream_offset off) { return off; }
48
49# else // # ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
50
51inline std::streampos offset_to_position(stream_offset off)
52{ return std::streampos(std::mbstate_t(), off); }
53
54# endif // # ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
55
56//------------------Definition of position_to_offset--------------------------//
57
58// Hande custom pos_type's
59template<typename PosType>
60inline stream_offset position_to_offset(PosType pos)
61{ return std::streamoff(pos); }
62
63# ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
64
65inline stream_offset position_to_offset(std::streampos pos) { return pos; }
66
67# else // # ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
68
69// In the Dinkumware standard library, a std::streampos consists of two stream
70// offsets -- _Fpos, of type std::fpos_t, and _Myoff, of type std::streamoff --
71// together with a conversion state. A std::streampos is converted to a
72// boost::iostreams::stream_offset by extracting the two stream offsets and
73// summing them. The value of _Fpos can be extracted using the implementation-
74// defined member functions seekpos() or get_fpos_t(), depending on the
75// Dinkumware version. The value of _Myoff cannot be extracted directly, but can
76// be calculated as the difference between the result of converting the
77// std::fpos to a std::streamoff and the result of converting the member _Fpos
78// to a long. The latter operation is accomplished with the macro _FPOSOFF,
79// which works correctly on platforms where std::fpos_t is an integral type and
80// platforms where it is a struct
81
82// Converts a std::fpos_t to a stream_offset
83inline stream_offset fpos_t_to_offset(std::fpos_t pos)
84{
85# if defined(_POSIX_) || (_INTEGRAL_MAX_BITS >= 64) || defined(__IBMCPP__)
86 return pos;
87# else
88 return _FPOSOFF(pos);
89# endif
90}
91
92// Extracts the member _Fpos from a std::fpos
93inline std::fpos_t streampos_to_fpos_t(std::streampos pos)
94{
95# if defined (_CPPLIB_VER) || defined(__IBMCPP__)
96 return pos.seekpos();
97# else
98 return pos.get_fpos_t();
99# endif
100}
101
102inline stream_offset position_to_offset(std::streampos pos)
103{
104 return fpos_t_to_offset(streampos_to_fpos_t(pos)) +
105 static_cast<stream_offset>(
106 static_cast<std::streamoff>(pos) -
107 _FPOSOFF(streampos_to_fpos_t(pos))
108 );
109}
110
111# endif // # ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
112
113} } // End namespaces iostreams, boost.
114
115#include <boost/iostreams/detail/config/enable_warnings.hpp>
116
117#endif // #ifndef BOOST_IOSTREAMS_POSITIONING_HPP_INCLUDED
118

source code of boost/boost/iostreams/positioning.hpp