113 lines
3.9 KiB
C++
113 lines
3.9 KiB
C++
|
// (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.
|
||
|
|
|
||
|
|
// To do: handle bidirection streams and output-seekable components.
|
||
|
|
|
||
|
|
#ifndef BOOST_IOSTREAMS_SKIP_HPP_INCLUDED
|
||
|
|
#define BOOST_IOSTREAMS_SKIP_HPP_INCLUDED
|
||
|
|
|
||
|
|
#if defined(_MSC_VER)
|
||
|
|
# pragma once
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#include <boost/iostreams/char_traits.hpp>
|
||
|
|
#include <boost/iostreams/detail/ios.hpp> // failure.
|
||
|
|
#include <boost/iostreams/operations.hpp>
|
||
|
|
#include <boost/iostreams/seek.hpp>
|
||
|
|
#include <boost/iostreams/traits.hpp>
|
||
|
|
#include <boost/mpl/and.hpp>
|
||
|
|
#include <boost/mpl/bool.hpp>
|
||
|
|
#include <boost/mpl/or.hpp>
|
||
|
|
#include <boost/throw_exception.hpp>
|
||
|
|
#include <boost/type_traits/is_convertible.hpp>
|
||
|
|
|
||
|
|
namespace boost { namespace iostreams {
|
||
|
|
|
||
|
|
namespace detail {
|
||
|
|
|
||
|
|
template<typename Device>
|
||
|
|
void skip(Device& dev, stream_offset off, mpl::true_)
|
||
|
|
{ iostreams::seek(dev, off, BOOST_IOS::cur); }
|
||
|
|
|
||
|
|
template<typename Device>
|
||
|
|
void skip(Device& dev, stream_offset off, mpl::false_)
|
||
|
|
{ // gcc 2.95 needs namespace qualification for char_traits.
|
||
|
|
typedef typename char_type_of<Device>::type char_type;
|
||
|
|
typedef iostreams::char_traits<char_type> traits_type;
|
||
|
|
for (stream_offset z = 0; z < off; ) {
|
||
|
|
typename traits_type::int_type c;
|
||
|
|
if (traits_type::is_eof(c = iostreams::get(dev)))
|
||
|
|
boost::throw_exception(BOOST_IOSTREAMS_FAILURE("bad skip offset"));
|
||
|
|
if (!traits_type::would_block(c))
|
||
|
|
++z;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
template<typename Filter, typename Device>
|
||
|
|
void skip( Filter& flt, Device& dev, stream_offset off,
|
||
|
|
BOOST_IOS::openmode which, mpl::true_ )
|
||
|
|
{ boost::iostreams::seek(flt, dev, off, BOOST_IOS::cur, which); }
|
||
|
|
|
||
|
|
template<typename Filter, typename Device>
|
||
|
|
void skip( Filter& flt, Device& dev, stream_offset off,
|
||
|
|
BOOST_IOS::openmode, mpl::false_ )
|
||
|
|
{
|
||
|
|
typedef typename char_type_of<Device>::type char_type;
|
||
|
|
char_type c;
|
||
|
|
for (stream_offset z = 0; z < off; ) {
|
||
|
|
std::streamsize amt;
|
||
|
|
if ((amt = iostreams::read(flt, dev, &c, 1)) == -1)
|
||
|
|
boost::throw_exception(BOOST_IOSTREAMS_FAILURE("bad skip offset"));
|
||
|
|
if (amt == 1)
|
||
|
|
++z;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
} // End namespace detail.
|
||
|
|
|
||
|
|
template<typename Device>
|
||
|
|
void skip(Device& dev, stream_offset off)
|
||
|
|
{
|
||
|
|
typedef typename mode_of<Device>::type mode;
|
||
|
|
typedef mpl::or_<
|
||
|
|
is_convertible<mode, input_seekable>,
|
||
|
|
is_convertible<mode, output_seekable>
|
||
|
|
> can_seek;
|
||
|
|
BOOST_STATIC_ASSERT(
|
||
|
|
(can_seek::value || is_convertible<mode, input>::value)
|
||
|
|
);
|
||
|
|
detail::skip(dev, off, can_seek());
|
||
|
|
}
|
||
|
|
|
||
|
|
template<typename Filter, typename Device>
|
||
|
|
void skip( Filter& flt, Device& dev, stream_offset off,
|
||
|
|
BOOST_IOS::openmode which = BOOST_IOS::in | BOOST_IOS::out )
|
||
|
|
{
|
||
|
|
typedef typename mode_of<Filter>::type filter_mode;
|
||
|
|
typedef typename mode_of<Device>::type device_mode;
|
||
|
|
typedef mpl::or_<
|
||
|
|
mpl::and_<
|
||
|
|
is_convertible<filter_mode, input_seekable>,
|
||
|
|
is_convertible<device_mode, input_seekable>
|
||
|
|
>,
|
||
|
|
mpl::and_<
|
||
|
|
is_convertible<filter_mode, output_seekable>,
|
||
|
|
is_convertible<device_mode, output_seekable>
|
||
|
|
>
|
||
|
|
> can_seek;
|
||
|
|
BOOST_STATIC_ASSERT(
|
||
|
|
( can_seek::value ||
|
||
|
|
(is_convertible<filter_mode, input>::value &&
|
||
|
|
is_convertible<device_mode, input>::value) )
|
||
|
|
);
|
||
|
|
detail::skip(flt, dev, off, which, can_seek());
|
||
|
|
}
|
||
|
|
|
||
|
|
} } // End namespaces iostreams, boost.
|
||
|
|
|
||
|
|
#endif // #ifndef BOOST_IOSTREAMS_SKIP_HPP_INCLUDED //------------------------//
|