| /* |
| * 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.expr.fn.impl; |
| |
| import org.apache.drill.common.types.TypeProtos.MinorType; |
| import org.apache.drill.exec.vector.complex.impl.SingleMapReaderImpl; |
| import org.apache.drill.exec.vector.complex.reader.FieldReader; |
| |
| public class IsEmptyUtils { |
| |
| /** |
| * This function recursively traverses a Drill map to determine whether the map is empty or not. |
| * @param reader A {@link FieldReader} containing the field in question |
| * @return True if the field contains no data, false if it does. |
| */ |
| public static boolean mapIsEmpty(FieldReader reader) { |
| |
| if (reader.getType().getMinorType() == MinorType.MAP) { |
| SingleMapReaderImpl mapReader = (SingleMapReaderImpl) reader; |
| |
| // If the map reader has no fields return true |
| if (!mapReader.iterator().hasNext()) { |
| return true; |
| } |
| // Now check to see whether the fields contain anything |
| boolean isEmpty = true; |
| for (String fieldName : reader) { |
| FieldReader fieldReader = reader.reader(fieldName); |
| if (fieldReader.isSet() && fieldReader.getType().getMinorType() == MinorType.MAP) { |
| boolean innerMapIsEmpty = mapIsEmpty(fieldReader); |
| |
| if (!innerMapIsEmpty) { |
| isEmpty = false; |
| } |
| |
| } else if (fieldReader.isSet()) { |
| isEmpty = false; |
| } |
| } |
| return isEmpty; |
| } else { |
| return ! reader.isSet(); |
| } |
| } |
| } |