boost/iostreams/positioning.hpp
// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
// (C) Copyright 2003-2007 Jonathan Turkanis
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
// See http://www.boost.org/libs/iostreams for documentation.
// Thanks to Gareth Sylvester-Bradley for the Dinkumware versions of the
// positioning functions.
#ifndef BOOST_IOSTREAMS_POSITIONING_HPP_INCLUDED
#define BOOST_IOSTREAMS_POSITIONING_HPP_INCLUDED
#if defined(_MSC_VER)
# pragma once
#endif
#include <boost/config.hpp>
#include <boost/cstdint.hpp>
#include <boost/integer_traits.hpp>
#include <boost/iostreams/detail/config/codecvt.hpp> // mbstate_t.
#include <boost/iostreams/detail/config/fpos.hpp>
#include <boost/iostreams/detail/ios.hpp> // streamoff, streampos.
// Must come last.
#include <boost/iostreams/detail/config/disable_warnings.hpp>
#ifdef BOOST_NO_STDC_NAMESPACE
namespace std { using ::fpos_t; }
#endif
namespace boost { namespace iostreams {
//------------------Definition of stream_offset-------------------------------//
typedef boost::intmax_t stream_offset;
//------------------Definition of stream_offset_to_streamoff------------------//
inline std::streamoff stream_offset_to_streamoff(stream_offset off)
{ return static_cast<stream_offset>(off); }
//------------------Definition of offset_to_position--------------------------//
# ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
inline std::streampos offset_to_position(stream_offset off) { return off; }
# else // # ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
inline std::streampos offset_to_position(stream_offset off)
{ return std::streampos(std::mbstate_t(), off); }
# endif // # ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
//------------------Definition of position_to_offset--------------------------//
// Hande custom pos_type's
template<typename PosType>
inline stream_offset position_to_offset(PosType pos)
{ return std::streamoff(pos); }
# ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
inline stream_offset position_to_offset(std::streampos pos) { return pos; }
# else // # ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
// In the Dinkumware standard library, a std::streampos consists of two stream
// offsets -- _Fpos, of type std::fpos_t, and _Myoff, of type std::streamoff --
// together with a conversion state. A std::streampos is converted to a
// boost::iostreams::stream_offset by extracting the two stream offsets and
// summing them. The value of _Fpos can be extracted using the implementation-
// defined member functions seekpos() or get_fpos_t(), depending on the
// Dinkumware version. The value of _Myoff cannot be extracted directly, but can
// be calculated as the difference between the result of converting the
// std::fpos to a std::streamoff and the result of converting the member _Fpos
// to a long. The latter operation is accomplished with the macro _FPOSOFF,
// which works correctly on platforms where std::fpos_t is an integral type and
// platforms where it is a struct
// Converts a std::fpos_t to a stream_offset
inline stream_offset fpos_t_to_offset(std::fpos_t pos)
{
# if defined(_POSIX_) || (_INTEGRAL_MAX_BITS >= 64) || defined(__IBMCPP__)
return pos;
# else
return _FPOSOFF(pos);
# endif
}
// Extracts the member _Fpos from a std::fpos
inline std::fpos_t streampos_to_fpos_t(std::streampos pos)
{
# if defined (_CPPLIB_VER) || defined(__IBMCPP__)
return pos.seekpos();
# else
return pos.get_fpos_t();
# endif
}
inline stream_offset position_to_offset(std::streampos pos)
{
return fpos_t_to_offset(streampos_to_fpos_t(pos)) +
static_cast<stream_offset>(
static_cast<std::streamoff>(pos) -
_FPOSOFF(streampos_to_fpos_t(pos))
);
}
# endif // # ifndef BOOST_IOSTREAMS_HAS_DINKUMWARE_FPOS
} } // End namespaces iostreams, boost.
#include <boost/iostreams/detail/config/enable_warnings.hpp>
#endif // #ifndef BOOST_IOSTREAMS_POSITIONING_HPP_INCLUDED