#ifndef VIRTUALSEEKER_H
#define VIRTUALSEEKER_H

#include "zipios++/zipios-config.h"

#include "zipios++/meta-iostreams.h"


namespace zipios {

using std::ios  ;
using std::cerr ;
using std::endl ;

/** VirtualSeeker is a simple class that keeps track of a set of
    specified 'virtual' file endings that mark a subset of a real
    file. An example of its use (and its reason for existence) is to
    keep track of the file endings of a Zip file embedded in another
    file. */
class VirtualSeeker {
public:
  inline VirtualSeeker( int start_offset = 0, int end_offset = 0) ;
  inline void setOffsets( int  start_offset, int  end_offset ) ;
  inline void getOffsets( int &start_offset, int &end_offset ) const ;
  inline int startOffset() const ;
  inline int   endOffset() const ;
  inline void vseekg( istream &is, int offset, ios::seekdir sd ) const ;
  inline int vtellg( istream &is ) const ;
private:
  // start and end offsets
  int _s_off, _e_off ;
};



VirtualSeeker::VirtualSeeker( int start_offset, int end_offset ) 
  : _s_off( start_offset ),
    _e_off( end_offset   )
{}


void VirtualSeeker::setOffsets( int start_offset, int end_offset ) {
  _s_off = start_offset ;
  _e_off = end_offset   ;
}


void VirtualSeeker::getOffsets( int &start_offset, int &end_offset ) const {
  start_offset = _s_off ;
  end_offset   = _e_off ;
}


int VirtualSeeker::startOffset() const {
  return _s_off ;
}


int VirtualSeeker::endOffset() const {
  return _e_off ;
}

void VirtualSeeker::vseekg( istream &is, int offset, ios::seekdir sd ) const {
  if ( sd == ios::cur )
    is.seekg( offset, sd ) ;
  else if ( sd == ios::beg )
      is.seekg( offset + _s_off,  sd ) ;
  else if ( sd == ios::end )
    is.seekg( offset - _e_off, sd ) ;
  else 
    cerr << "VirtualSeekManager::seekg: error - not supposed to happen!" << endl ;
}


int  VirtualSeeker::vtellg( istream &is ) const {
  return static_cast< int >( is.tellg() ) - _s_off ;
}


} // namespace

#endif

/** \file 
    Header file that defines VirtualSeeker.
*/

/*
  Zipios++ - a small C++ library that provides easy access to .zip files.
  Copyright (C) 2000  Thomas Søndergaard
  
  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2 of the License, or (at your option) any later version.
  
  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.
  
  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
*/
