EvtStreamInputIterator.hh

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#ifndef EVT_STREAM_INPUT_ITERATOR_HH
#define EVT_STREAM_INPUT_ITERATOR_HH
 
#include "EvtGenBase/EvtStreamAdapter.hh"
 
#include <cstddef>
#include <iterator>
 
using std::input_iterator_tag;
 
// Adapters are used to convert various types of input streams
// into an iteratable interface.
 
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() : m_counter( 0 ) {}
 
    EvtStreamInputIterator( const EvtStreamInputIterator& other ) :
        m_counter( other.m_counter ? other.m_counter->clone() : nullptr ),
        m_currentValue( other.m_currentValue )
    {
    }
 
    EvtStreamInputIterator( EvtStreamAdapter<Point>& counter ) :
        m_counter( counter.clone() )
    {
        m_currentValue = m_counter->currentValue();
    }
 
    ~EvtStreamInputIterator()
    {
        if ( m_counter )
            delete m_counter;
    }
 
    reference operator*() const { return m_currentValue; }
 
    EvtStreamInputIterator& operator++()
    {
        m_read();
        return *this;
    }
 
    EvtStreamInputIterator operator++( int )
    {
        EvtStreamInputIterator tmp = *this;
        m_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>* m_counter;
    value_type m_currentValue;
 
    bool pastEnd() const
    {
        bool ret = true;
        if ( m_counter )
            ret = m_counter->pastEnd();
        return ret;
    }
 
    // Advances the iterator
 
    void m_read()
    {
        m_counter->advance();
        m_currentValue = m_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