paul-rogers commented on a change in pull request #1870: DRILL-7359: Add support for DICT type in RowSet Framework URL: https://github.com/apache/drill/pull/1870#discussion_r347115511
########## File path: exec/vector/src/main/java/org/apache/drill/exec/vector/accessor/reader/NullReader.java ########## @@ -0,0 +1,369 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.drill.exec.vector.accessor.reader; + +import org.apache.drill.common.types.TypeProtos; +import org.apache.drill.exec.record.metadata.ColumnMetadata; +import org.apache.drill.exec.record.metadata.TupleMetadata; +import org.apache.drill.exec.record.metadata.VariantMetadata; +import org.apache.drill.exec.vector.accessor.ArrayReader; +import org.apache.drill.exec.vector.accessor.DictReader; +import org.apache.drill.exec.vector.accessor.ObjectReader; +import org.apache.drill.exec.vector.accessor.ObjectType; +import org.apache.drill.exec.vector.accessor.ScalarReader; +import org.apache.drill.exec.vector.accessor.TupleReader; +import org.apache.drill.exec.vector.accessor.ValueType; +import org.apache.drill.exec.vector.accessor.VariantReader; +import org.joda.time.Instant; +import org.joda.time.LocalDate; +import org.joda.time.LocalTime; +import org.joda.time.Period; + +import java.math.BigDecimal; + +/** + * Dummy reader which returns {@code null} for scalar types and itself for complex types. + */ +public class NullReader implements ScalarReader, ArrayReader, TupleReader, VariantReader, ObjectReader, DictReader { Review comment: See comments below. I think this is just a bit confusing; it is not clear when we'd use it and how clients would use it. As explained below, I *think* that if you need a reader for a missing element, you can use the existing scalar `NullReader`: just define a missing reader as a reader of scalar nulls. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
