@ Override public boolean preVisit ( Operator < ? > node ) { // check if node was already visited if ( ! this . visitedNodes . add ( node ) ) { return false ; } // apply the appropriate check method if ( node instanceof FileDataSinkBase ) { checkFileDataSink ( ( FileDataSinkBase < ? > ) node ) ; } else if ( node instanceof FileDataSourceBase ) { checkFileDataSource ( ( FileDataSourceBase < ? > ) node ) ; } else if ( node instanceof GenericDataSinkBase ) { checkDataSink ( ( GenericDataSinkBase < ? > ) node ) ; } else if ( node instanceof BulkIterationBase ) { checkBulkIteration ( ( BulkIterationBase < ? > ) node ) ; } else if ( node instanceof SingleInputOperator ) { checkSingleInputContract ( ( SingleInputOperator < ? , ? , ? > ) node ) ; } else if ( node instanceof DualInputOperator < ? , ? , ? , ? > ) { checkDualInputContract ( ( DualInputOperator < ? , ? , ? , ? > ) node ) ; } if ( node instanceof Validatable ) { ( ( Validatable ) node ) . check ( ) ; } return true ; }
Checks whether the node is correctly connected to its input .