initialize( result, iter, selectedColumns, exprs );
this.extractResult = result; this.selectedColumns = selectedColumns; this.helper = helper;  if ( this.selectedColumns == null ) { ArrayList aColMeta = helper.validatedColMetas; this.selectedColumns = new String[aColMeta.size( )]; for( int i=0; i<aColMeta.size( ); i++ ) { ExprMetaData meta = (ExprMetaData)aColMeta.get( i ); this.selectedColumns[i] = meta.getName( ); } }  if ( this.selectedColumns != null ) { for ( int i=0; i<this.selectedColumns.length; i++ ) { colSet.add( this.selectedColumns[i] ); } }
	DataIterator( IExtractionResults result, IResultIterator iter, 			String[] selectedColumns, Collection exprs )	{		initialize( result, iter, selectedColumns, exprs );	}