| /* |
| * 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.iotdb.db.queryengine.transformation.dag.column.unary.scalar; |
| |
| import org.apache.iotdb.db.queryengine.transformation.dag.column.ColumnTransformer; |
| import org.apache.iotdb.db.queryengine.transformation.dag.column.unary.UnaryColumnTransformer; |
| |
| import org.apache.tsfile.block.column.Column; |
| import org.apache.tsfile.block.column.ColumnBuilder; |
| import org.apache.tsfile.read.common.type.Type; |
| |
| public class DiffFunctionColumnTransformer extends UnaryColumnTransformer { |
| |
| // default is true |
| private final boolean ignoreNull; |
| |
| // cache the last non-null value |
| private double lastValue; |
| |
| // indicate whether lastValue is null |
| private boolean lastValueIsNull = true; |
| |
| public DiffFunctionColumnTransformer( |
| Type returnType, ColumnTransformer childColumnTransformer, boolean ignoreNull) { |
| super(returnType, childColumnTransformer); |
| this.ignoreNull = ignoreNull; |
| } |
| |
| @Override |
| protected void doTransform(Column column, ColumnBuilder columnBuilder) { |
| for (int i = 0, n = column.getPositionCount(); i < n; i++) { |
| if (column.isNull(i)) { |
| columnBuilder.appendNull(); // currValue is null, append null |
| |
| // When currValue is null: |
| // ignoreNull = true, keep lastValueIsNull as before |
| // ignoreNull = false, update lastValueIsNull to true |
| lastValueIsNull |= !ignoreNull; |
| } else { |
| double currValue = childColumnTransformer.getType().getDouble(column, i); |
| if (lastValueIsNull) { |
| columnBuilder.appendNull(); // lastValue is null, append null |
| } else { |
| returnType.writeDouble(columnBuilder, currValue - lastValue); |
| } |
| |
| lastValue = currValue; // currValue is not null, update lastValue |
| lastValueIsNull = false; |
| } |
| } |
| } |
| } |