sl@0: // (C) Copyright Jonathan Turkanis 2003.
sl@0: // Distributed under the Boost Software License, Version 1.0. (See accompanying
sl@0: // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
sl@0: 
sl@0: // See http://www.boost.org/libs/iostreams for documentation.
sl@0: 
sl@0: // To do: handle bidirection streams and output-seekable components.
sl@0: 
sl@0: #ifndef BOOST_IOSTREAMS_SKIP_HPP_INCLUDED
sl@0: #define BOOST_IOSTREAMS_SKIP_HPP_INCLUDED
sl@0: 
sl@0: #if defined(_MSC_VER) && (_MSC_VER >= 1020)
sl@0: # pragma once
sl@0: #endif
sl@0: 
sl@0: #include <boost/iostreams/char_traits.hpp>
sl@0: #include <boost/iostreams/detail/ios.hpp>  // failure.
sl@0: #include <boost/iostreams/operations.hpp>
sl@0: #include <boost/iostreams/traits.hpp>
sl@0: #include <boost/mpl/and.hpp>
sl@0: #include <boost/mpl/bool.hpp>
sl@0: #include <boost/type_traits/is_convertible.hpp>
sl@0: 
sl@0: namespace boost { namespace iostreams {
sl@0: 
sl@0: namespace detail {
sl@0: 
sl@0: template<typename Device>
sl@0: void skip(Device& dev, stream_offset off, mpl::true_)
sl@0: { iostreams::seek(dev, off, BOOST_IOS::cur); }
sl@0: 
sl@0: template<typename Device>
sl@0: void skip(Device& dev, stream_offset off, mpl::false_)
sl@0: {   // gcc 2.95 needs namespace qualification for char_traits.
sl@0:     typedef typename char_type_of<Device>::type  char_type;
sl@0:     typedef iostreams::char_traits<char_type>    traits_type;
sl@0:     for (stream_offset z = 0; z < off; ) {
sl@0:         typename traits_type::int_type c;
sl@0:         if (traits_type::is_eof(c = iostreams::get(dev)))
sl@0:             throw BOOST_IOSTREAMS_FAILURE("bad skip offset");
sl@0:         if (!traits_type::would_block(c))
sl@0:             ++z;
sl@0:     }
sl@0: }
sl@0: 
sl@0: template<typename Filter, typename Device>
sl@0: void skip(Filter& flt, Device& dev, stream_offset off, mpl::true_)
sl@0: { flt.seek(dev, off, BOOST_IOS::cur); }
sl@0: 
sl@0: template<typename Filter, typename Device>
sl@0: void skip(Filter& flt, Device& dev, stream_offset off, mpl::false_)
sl@0: { 
sl@0:     typedef typename char_type_of<Device>::type char_type;
sl@0:     char_type c;
sl@0:     for (stream_offset z = 0; z < off; ) {
sl@0:         std::streamsize amt;
sl@0:         if ((amt = iostreams::read(flt, dev, &c, 1)) == -1)
sl@0:             throw BOOST_IOSTREAMS_FAILURE("bad skip offset");
sl@0:         if (amt == 1)
sl@0:             ++z;
sl@0:     }
sl@0: }
sl@0: 
sl@0: } // End namespace detail.
sl@0: 
sl@0: template<typename Device>
sl@0: void skip(Device& dev, stream_offset off)
sl@0: { 
sl@0:     typedef typename mode_of<Device>::type mode;
sl@0:     detail::skip(dev, off, is_convertible<mode, seekable>());
sl@0: }
sl@0: 
sl@0: template<typename Filter, typename Device>
sl@0: void skip(Filter& flt, Device& dev, stream_offset off)
sl@0: { 
sl@0:     typedef typename mode_of<Filter>::type                     filter_mode;
sl@0:     typedef typename mode_of<Device>::type                     device_mode;
sl@0:     typedef mpl::and_<
sl@0:                 is_convertible<filter_mode, output_seekable>,
sl@0:                 is_convertible<device_mode, output_seekable>
sl@0:             >                                                  can_seek;
sl@0:     detail::skip(flt, dev, off, can_seek());
sl@0: }
sl@0: 
sl@0: } } // End namespaces iostreams, boost.
sl@0: 
sl@0: #endif // #ifndef BOOST_IOSTREAMS_SKIP_HPP_INCLUDED //------------------------//