EvtStreamInputIterator.hh

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/*******************************************************************************
 * Project: BaBar detector at the SLAC PEP-II B-factory
 * Package: EvtGenBase
 *    File: $Id: EvtStreamInputIterator.hh,v 1.2 2015/04/07 07:39:37 pingrg Exp $
 *  Author: Alexei Dvoretskii, dvoretsk@slac.stanford.edu, 2001-2002
 *
 * Copyright (C) 2002 Caltech
 *******************************************************************************/
 
// Adapters are used to convert various types of input streams
// into an iteratable interface.
 
#ifndef EVT_STREAM_INPUT_ITERATOR_HH
#define EVT_STREAM_INPUT_ITERATOR_HH
 
#include "EvtStreamAdapter.hh"
#include <iterator>
using std::input_iterator_tag;
 
template <class Point> class EvtStreamInputIterator {
public:
  typedef input_iterator_tag iterator_category;
  typedef Point              value_type;
  // typedef ptrdiff_t          difference_type;
  typedef const Point* pointer;
  typedef const Point& reference;
 
  EvtStreamInputIterator() : _counter( 0 ) {}
 
  EvtStreamInputIterator( const EvtStreamInputIterator& other )
      : _counter( other._counter ? other._counter->clone() : 0 )
      , _currentValue( other._currentValue ) {}
 
  EvtStreamInputIterator( EvtStreamAdapter<Point>& counter ) : _counter( counter.clone() ) {
    _currentValue = _counter->currentValue();
  }
 
  ~EvtStreamInputIterator() {
    if ( _counter ) delete _counter;
  }
 
  reference operator*() const { return _currentValue; }
 
  EvtStreamInputIterator& operator++() {
    _read();
    return *this;
  }
 
  EvtStreamInputIterator operator++( int ) {
    EvtStreamInputIterator tmp = *this;
    _read();
    return tmp;
  }
 
  bool operator==( const EvtStreamInputIterator& other ) const {
    // Equality is only defined for two past the end iterators
    return ( pastEnd() && other.pastEnd() );
  }
 
protected:
  EvtStreamAdapter<Point>* _counter;
  value_type               _currentValue;
 
  bool pastEnd() const {
    bool ret = true;
    if ( _counter ) ret = _counter->pastEnd();
    return ret;
  }
 
  // Advances the iterator
 
  void _read() {
 
    _counter->advance();
    _currentValue = _counter->currentValue();
  }
};
 
// For adaptable generators these shorthand functions can be used
// to construct iterators.
 
template <class Generator>
EvtStreamInputIterator<typename Generator::result_type> iter( Generator gen, int N = 0 ) {
  typedef typename Generator::result_type Point;
  EvtGenStreamAdapter<Point, Generator>   counter( gen, N );
  return EvtStreamInputIterator<Point>( counter );
}
 
#endif