fixedstreambuf.h

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#ifndef fixedstreambuf_h
#define fixedstreambuf_h
/*
________________________________________________________________________

 (C) dGB Beheer B.V.; (LICENSE) http://opendtect.org/OpendTect_license.txt
 Author:        Bert
 Date:          Feb 2009
 RCS:           $Id$
________________________________________________________________________

*/

#include <streambuf>


namespace std
{

mClass(Basic) fixedstreambuf : public streambuf
{
public:

fixedstreambuf( char_type* b, off_type sz, bool manbuf=false )
    : mine_(manbuf)
    , newpos_(0)
{
    setbuf( b, sz );
}

~fixedstreambuf()
{
    if ( mine_ )
        delete [] buf_;
}

virtual fixedstreambuf* setbuf( char_type* b, streamsize n )
{
    buf_ = b; sz_ = n;
    setg( buf_, buf_, buf_ + sz_ );
    setp( buf_, buf_ + sz_ );

    return this;
}

virtual pos_type seekoff( off_type offs, ios_base::seekdir sd,
                          ios_base::openmode which )
{
    newpos_ = offs;
    if ( sd == ios_base::cur )
        newpos_ += which == ios_base::in ? gptr() - buf_ : pptr() - buf_;
    else if ( sd == ios_base::end )
        newpos_ = sz_ + newpos_;

    return seekpos( newpos_, which );
}

virtual pos_type seekpos( pos_type newpos, ios_base::openmode which )
{
    if ( newpos_ < 0 || newpos_ >= sz_ )
        newpos_ = -1;
    else if ( which == ios_base::in )
        setg( buf_, buf_+newpos_, buf_ + sz_ );
    else
        setp( buf_+newpos_, buf_ + sz_ );

    return newpos_;
}

virtual streamsize xsgetn( char_type* s, streamsize n )
{
    streamsize toget = n;
    const od_int64 memsz = epptr() - pptr();
    if ( toget > memsz && memsz >= 0  )
        toget = memsz;

    OD::memCopy( s, gptr(), (size_t)toget );
    gbump( (int) toget );

    return toget;
}

virtual streamsize xsputn( const char_type* s, streamsize n )
{
    streamsize toput = n;
    const od_int64 memsz = epptr() - pptr();
    if ( toput > memsz && memsz >= 0  )
        toput = memsz;

    OD::memCopy( pptr(), s, (size_t)toput );
    pbump( (int)toput );

    return toput;
}

    char_type*  buf_;
    off_type    sz_;
    bool        mine_;
    off_type    newpos_;
};

} // namespace std


#endif