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