LCIterator.h

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// -*- C++ -*-
#ifndef  UTIL_LCIterator_include
#define  UTIL_LCIterator_include

#include <string>
#include <sstream>
#include <typeinfo>
#include "EVENT/LCEvent.h"
#include "EVENT/LCCollection.h"
#include "lcio.h"

namespace UTIL {

  template <class T>
  class LCIterator{
  
    LCIterator<T>() {} 
  
  public:

    LCIterator<T>( EVENT::LCEvent* evt, const std::string& name ) : _i(0), _col(0) {
    
    
      try{
      
    _col = evt->getCollection( name ) ;
      
      } catch( EVENT::DataNotAvailableException& ) { }  
    
      _n = (_col ? _col->getNumberOfElements() : 0 ) ;
    
      if( _n > 0 ){
      
    T* t = dynamic_cast<T*>(  _col->getElementAt(0)  );

    if( t == 0 ){

      std::stringstream s ;
      s << " invalid iterator type  : " << typeid( t ).name() << " for collection " <<  name  << std::endl ; 
      throw lcio::Exception( s.str() ) ;
    }
      }
    }
  
  
    LCIterator<T>( const EVENT::LCCollection* col) : _i(0) , _col( col ) {
    
      _n = (_col ? _col->getNumberOfElements() : 0 ) ;
    
      if( _n > 0 ){
      
    T* t = dynamic_cast<T*>(  _col->getElementAt(0)  );
      
    if( t == 0 ){
    
      std::stringstream s ;
      s << " invalid iterator type  : " << typeid( t ).name() << " for collection " << std::endl ; 
      throw lcio::Exception( s.str() ) ;
    }
      }
    }
  
    T* next(){
    
      if( _i < _n ) 
    return (T*)_col->getElementAt( _i++ )  ;
      //      return dynamic_cast<T*>( _col->getElementAt( _i++ ) ) ;
      else
    return 0 ;
    }
  
    int size() { return _n ; }
  

    const EVENT::LCCollection* operator->() { return _col ; }

    const EVENT::LCCollection* operator()() { return _col ; }

  private:
    int _n{0}, _i ;
    const EVENT::LCCollection* _col ;
  } ;

} // namespace UTIL

#endif