// (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) && (_MSC_VER >= 1020) | |
# 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 //------------------------// |