public static RexNode fromFieldAccess ( final RowSignature rowSignature , final Project project , final int fieldNumber ) { if ( project == null ) { // I don't think the factory impl matters here. return RexInputRef . of ( fieldNumber , rowSignature . getRelDataType ( new JavaTypeFactoryImpl ( ) ) ) ; } else { return project . getChildExps ( ) . get ( fieldNumber ) ; } }
Translate a field access possibly through a projection to an underlying Druid dataSource .