restrict_impl.hpp

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namespace detail {

//--------------Implementation of restricted_indirect_device------------------//

template<typename Device>
restricted_indirect_device<Device>::restricted_indirect_device
    (param_type dev, stream_offset off, stream_offset len)
    : device_adapter<Device>(dev), beg_(off), pos_(off), 
      end_(len != -1 ? off + len : -1)
{
    if (len < -1 || off < 0)
        throw BOOST_IOSTREAMS_FAILURE("bad offset");
    iostreams::skip(this->component(), off);
}

template<typename Device>
inline std::streamsize restricted_indirect_device<Device>::read
    (char_type* s, std::streamsize n)
{
    using namespace std;
    std::streamsize amt =
        end_ != -1 ?
            (std::min) (n, static_cast<std::streamsize>(end_ - pos_)) :
            n;
    std::streamsize result = iostreams::read(this->component(), s, amt);
    if (result != -1)
        pos_ += result;
    return result;
}

template<typename Device>
inline std::streamsize restricted_indirect_device<Device>::write
    (const char_type* s, std::streamsize n)
{
    if (end_ != -1 && pos_ + n >= end_)
        bad_write();
    std::streamsize result = iostreams::write(this->component(), s, n);
    pos_ += result;
    return result;
}

template<typename Device>
std::streampos restricted_indirect_device<Device>::seek
    (stream_offset off, BOOST_IOS::seekdir way)
{
    stream_offset next;
    if (way == BOOST_IOS::beg) {
        next = beg_ + off;
    } else if (way == BOOST_IOS::cur) {
        next = pos_ + off;
    } else if (end_ != -1) {
        next = end_ + off;
    } else {
        // Restriction is half-open; seek relative to the actual end.
        pos_ = iostreams::seek(this->component(), off, BOOST_IOS::end);
        if (pos_ < beg_)
            bad_seek();
        return offset_to_position(pos_ - beg_);
    }
    if (next < beg_ || end_ != -1 && next >= end_)
        bad_seek();
    pos_ = iostreams::seek(this->component(), next - pos_, BOOST_IOS::cur);
    return offset_to_position(pos_ - beg_);
}

//--------------Implementation of restricted_direct_device--------------------//

template<typename Device>
restricted_direct_device<Device>::restricted_direct_device
    (const Device& dev, stream_offset off, stream_offset len)
    : device_adapter<Device>(dev), beg_(0), end_(0)
{
    std::pair<char_type*, char_type*> seq =
        sequence(is_convertible<category, input>());
    if ( off < 0 || len < -1 || 
         len != -1 && off + len > seq.second - seq.first )
    {
        throw BOOST_IOSTREAMS_FAILURE("bad offset");
    }
    beg_ = seq.first + off;
    end_ = len != -1 ? 
        seq.first + off + len :
        seq.second;
}

template<typename Device>
typename restricted_direct_device<Device>::pair_type
restricted_direct_device<Device>::input_sequence()
{
    BOOST_STATIC_ASSERT((is_convertible<category, input>::value));
    return std::make_pair(beg_, end_);
}

template<typename Device>
typename restricted_direct_device<Device>::pair_type
restricted_direct_device<Device>::output_sequence()
{
    BOOST_STATIC_ASSERT((is_convertible<category, output>::value));
    return std::make_pair(beg_, end_);
}

template<typename Device>
typename restricted_direct_device<Device>::pair_type
restricted_direct_device<Device>::sequence(mpl::true_)
{ return iostreams::input_sequence(this->component()); }

template<typename Device>
typename restricted_direct_device<Device>::pair_type
restricted_direct_device<Device>::sequence(mpl::false_)
{ return iostreams::output_sequence(this->component()); }

//--------------Implementation of restricted_filter---------------------------//

template<typename Filter>
restricted_filter<Filter>::restricted_filter
    (const Filter& flt, stream_offset off, stream_offset len)
    : filter_adapter<Filter>(flt), beg_(off),
      pos_(off), end_(len != -1 ? off + len : -1), open_(false)
{
    if (len < -1 || off < 0)
        throw BOOST_IOSTREAMS_FAILURE("bad offset");
}

} // End namespace detail.

} } // End namespaces iostreams, boost.

#elif defined(BOOST_IOSTREAMS_RESTRICT)

namespace boost { namespace iostreams {

//--------------Implementation of restrict/slice------------------------------//

// Note: The following workarounds are patterned after resolve.hpp. It has not
// yet been confirmed that they are necessary.

# ifndef BOOST_IOSTREAMS_BROKEN_OVERLOAD_RESOLUTION //------------------------//
#  ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //------------------------------//

template<typename T>
restriction<T> 
BOOST_IOSTREAMS_RESTRICT( const T& t, stream_offset off, stream_offset len = -1
                          BOOST_IOSTREAMS_DISABLE_IF_STREAM(T) )
{ return restriction<T>(t, off, len); }

template<typename Ch, typename Tr>
restriction< std::basic_streambuf<Ch, Tr> >
BOOST_IOSTREAMS_RESTRICT( std::basic_streambuf<Ch, Tr>& sb, stream_offset off, 
                          stream_offset len = -1 )
{ return restriction< std::basic_streambuf<Ch, Tr> >(sb, off, len); }

template<typename Ch, typename Tr>
restriction< std::basic_istream<Ch, Tr> >
BOOST_IOSTREAMS_RESTRICT
    (std::basic_istream<Ch, Tr>& is, stream_offset off, stream_offset len = -1)
{ return restriction< std::basic_istream<Ch, Tr> >(is, off, len); }

template<typename Ch, typename Tr>
restriction< std::basic_ostream<Ch, Tr> >
BOOST_IOSTREAMS_RESTRICT
    (std::basic_ostream<Ch, Tr>& os, stream_offset off, stream_offset len = -1)
{ return restriction< std::basic_ostream<Ch, Tr> >(os, off, len); }

template<typename Ch, typename Tr>
restriction< std::basic_iostream<Ch, Tr> >
BOOST_IOSTREAMS_RESTRICT
    (std::basic_iostream<Ch, Tr>& io, stream_offset off, stream_offset len = -1)
{ return restriction< std::basic_iostream<Ch, Tr> >(io, off, len); }

#  else // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //--------------------//

template<typename T>
restriction<T> 
BOOST_IOSTREAMS_RESTRICT( const T& t, stream_offset off, stream_offset len = -1
                          BOOST_IOSTREAMS_DISABLE_IF_STREAM(T) )
{ return restriction<T>(t, off, len); }

restriction<std::streambuf> 
BOOST_IOSTREAMS_RESTRICT
    (std::streambuf& sb, stream_offset off, stream_offset len = -1)
{ return restriction<std::streambuf>(sb, off, len); }

restriction<std::istream> 
BOOST_IOSTREAMS_RESTRICT
    (std::istream<Ch, Tr>& is, stream_offset off, stream_offset len = -1)
{ return restriction<std::istream>(is, off, len); }

restriction<std::ostream> 
BOOST_IOSTREAMS_RESTRICT
    (std::ostream<Ch, Tr>& os, stream_offset off, stream_offset len = -1)
{ return restriction<std::ostream>(os, off, len); }

restriction<std::iostream> 
BOOST_IOSTREAMS_RESTRICT
    (std::iostream<Ch, Tr>& io, stream_offset off, stream_offset len = -1)
{ return restriction<std::iostream>(io, off, len); }

#  endif // # ifndef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES //-------------------//
# else // #ifndef BOOST_IOSTREAMS_BROKEN_OVERLOAD_RESOLUTION //---------------//

template<typename T>
restriction<T> 
BOOST_IOSTREAMS_RESTRICT
    (const T& t, stream_offset off, stream_offset len, mpl::true_)
{   // Bad overload resolution.
    return restriction<T>(const_cast<T&>(t, off, len));
}

template<typename T>
restriction<T> 
BOOST_IOSTREAMS_RESTRICT
    (const T& t, stream_offset off, stream_offset len, mpl::false_)
{ return restriction<T>(t, off, len); }

template<typename T>
restriction<T> 
BOOST_IOSTREAMS_RESTRICT( const T& t, stream_offset off, stream_offset len = -1
                          BOOST_IOSTREAMS_DISABLE_IF_STREAM(T) )
{ return BOOST_IOSTREAMS_RESTRICT(t, off, len, is_std_io<T>()); }

# if !BOOST_WORKAROUND(__BORLANDC__, < 0x600) && \
     !BOOST_WORKAROUND(BOOST_MSVC, <= 1300) && \
     !defined(__GNUC__) // ---------------------------------------------------//

template<typename T>
restriction<T>
BOOST_IOSTREAMS_RESTRICT(T& t, stream_offset off, stream_offset len = -1)
{ return restriction<T>(t, off, len); }

#  endif // Borland 5.x, VC6-7.0 or GCC 2.9x //-------------------------------//
# endif // #ifndef BOOST_IOSTREAMS_BROKEN_OVERLOAD_RESOLUTION //--------------//

} } // End namespaces iostreams, boost.

#endif // #if !defined(BOOST_IOSTREAMS_RESTRICT_IMPL_HPP_INCLUDED) ...