// (C) Copyright Jonathan Turkanis 2003.

// 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.

#ifndef BOOST_IOSTREAMS_SEEK_HPP_INCLUDED

#define BOOST_IOSTREAMS_SEEK_HPP_INCLUDED

#if defined(_MSC_VER) && (_MSC_VER >= 1020)

# pragma once

#endif

#include <boost/config.hpp>  // DEDUCED_TYPENAME, MSVC.

#include <boost/integer_traits.hpp>

#include <boost/iostreams/categories.hpp>

#include <boost/iostreams/detail/dispatch.hpp>

#include <boost/iostreams/detail/ios.hpp>       // streamsize, seekdir, openmode.

#include <boost/iostreams/detail/streambuf.hpp>

#include <boost/iostreams/detail/wrap_unwrap.hpp>

#include <boost/iostreams/operations_fwd.hpp>

#include <boost/iostreams/positioning.hpp>

#include <boost/mpl/if.hpp>

// Must come last.

#include <boost/iostreams/detail/config/disable_warnings.hpp>

namespace boost { namespace iostreams {

namespace detail {

template<typename T>

struct seek_device_impl;

template<typename T>

struct seek_filter_impl;

} // End namespace detail.

template<typename T>

inline std::streampos

seek( T& t, stream_offset off, BOOST_IOS::seekdir way,

      BOOST_IOS::openmode which = BOOST_IOS::in | BOOST_IOS::out )

{ 

    using namespace detail;

    return seek_device_impl<T>::seek(detail::unwrap(t), off, way, which); 

}

template<typename T, typename Device>

inline std::streampos

seek( T& t, Device& dev, stream_offset off, BOOST_IOS::seekdir way,

      BOOST_IOS::openmode which = BOOST_IOS::in | BOOST_IOS::out )

{ 

    using namespace detail;

    return seek_filter_impl<T>::seek(detail::unwrap(t), dev, off, way, which);

}

namespace detail {

//------------------Definition of seek_device_impl----------------------------//

template<typename T>

struct seek_device_impl

    : mpl::if_<

          is_custom<T>,

          operations<T>,

          seek_device_impl<

              BOOST_DEDUCED_TYPENAME

              dispatch<

                  T, iostream_tag, istream_tag, ostream_tag,

                  streambuf_tag, two_head, any_tag

              >::type

          >

      >::type

    { };

struct seek_impl_basic_ios {

    template<typename T>

    static std::streampos seek( T& t, stream_offset off,

                                BOOST_IOS::seekdir way,

                                BOOST_IOS::openmode which )

    {

        if ( way == BOOST_IOS::beg &&

             ( off < integer_traits<std::streamoff>::const_min ||

               off > integer_traits<std::streamoff>::const_max ) )

        {

            return t.rdbuf()->pubseekpos(offset_to_position(off));

        } else {

            return t.rdbuf()->pubseekoff(off, way, which);

        }

    }

};

template<>

struct seek_device_impl<iostream_tag> : seek_impl_basic_ios { };

template<>

struct seek_device_impl<istream_tag> : seek_impl_basic_ios { };

template<>

struct seek_device_impl<ostream_tag> : seek_impl_basic_ios { };

template<>

struct seek_device_impl<streambuf_tag> {

    template<typename T>

    static std::streampos seek( T& t, stream_offset off,

                                BOOST_IOS::seekdir way,

                                BOOST_IOS::openmode which )

    {

        if ( way == BOOST_IOS::beg &&

             ( off < integer_traits<std::streamoff>::const_min ||

               off > integer_traits<std::streamoff>::const_max ) )

        {

            return t.BOOST_IOSTREAMS_PUBSEEKPOS(offset_to_position(off));

        } else {

            return t.BOOST_IOSTREAMS_PUBSEEKOFF(off, way, which);

        }

    }

};

template<>

struct seek_device_impl<two_head> {

    template<typename T>

    static std::streampos seek( T& t, stream_offset off,

                                BOOST_IOS::seekdir way,

                                BOOST_IOS::openmode which )

    { return t.seek(off, way, which); }

};

template<>

struct seek_device_impl<any_tag> {

    template<typename T>

    static std::streampos seek( T& t, stream_offset off,

                                BOOST_IOS::seekdir way,

                                BOOST_IOS::openmode )

    { return t.seek(off, way); }

};

//------------------Definition of seek_filter_impl----------------------------//

template<typename T>

struct seek_filter_impl

    : mpl::if_<

          is_custom<T>,

          operations<T>,

          seek_filter_impl<

              BOOST_DEDUCED_TYPENAME

              dispatch<T, two_head, any_tag>::type

          >

      >::type

    { };

template<>

struct seek_filter_impl<two_head> {

    template<typename T, typename Device>

    static std::streampos seek( T& t, Device& d,

                                stream_offset off,

                                BOOST_IOS::seekdir way,

                                BOOST_IOS::openmode which )

    { return t.seek(d, off, way, which); }

};

template<>

struct seek_filter_impl<any_tag> {

    template<typename T, typename Device>

    static std::streampos seek( T& t, Device& d,

                                stream_offset off,

                                BOOST_IOS::seekdir way,

                                BOOST_IOS::openmode )

    { return t.seek(d, off, way); }

};

} // End namespace detail.

} } // End namespaces iostreams, boost.

#include <boost/iostreams/detail/config/enable_warnings.hpp>

#endif // #ifndef BOOST_IOSTREAMS_SEEK_HPP_INCLUDED