fx19880617 commented on a change in pull request #5461: URL: https://github.com/apache/incubator-pinot/pull/5461#discussion_r436241645
########## File path: pinot-core/src/main/java/org/apache/pinot/core/operator/transform/function/CaseTransformFunction.java ########## @@ -0,0 +1,484 @@ +/** + * 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.pinot.core.operator.transform.function; + +import com.google.common.base.Preconditions; +import java.math.BigDecimal; +import java.util.ArrayList; +import java.util.List; +import java.util.Map; +import org.apache.pinot.core.common.DataSource; +import org.apache.pinot.core.operator.blocks.ProjectionBlock; +import org.apache.pinot.core.operator.transform.TransformResultMetadata; +import org.apache.pinot.core.plan.DocIdSetPlanNode; +import org.apache.pinot.spi.data.FieldSpec; + + +/** + * The <code>CaseTransformFunction</code> class implements the CASE-WHEN-THEN-ELSE transformation. + * + * The SQL Syntax is: + * CASE + * WHEN condition1 THEN result1 + * WHEN condition2 THEN result2 + * WHEN conditionN THEN resultN + * ELSE result + * END; + * + * Usage: + * case(${WHEN_STATEMENT_1}, ..., ${WHEN_STATEMENT_N}, + * ${THEN_EXPRESSION_1}, ..., ${THEN_EXPRESSION_N}, + * ${ELSE_EXPRESSION}) + * + * There are 2 * N + 1 arguments: + * <code>WHEN_STATEMENT_$i</code> is a <code>BinaryOperatorTransformFunction</code> represents <code>condition$i</code> + * <code>THEN_EXPRESSION_$i</code> is a <code>TransformFunction</code> represents <code>result$i</code> + * <code>ELSE_EXPRESSION</code> is a <code>TransformFunction</code> represents <code>result</code> + * + */ +public class CaseTransformFunction extends BaseTransformFunction { + public static final String FUNCTION_NAME = "case"; + private final List<TransformFunction> _whenStatements = new ArrayList<>(); + private final List<TransformFunction> _elseThenStatements = new ArrayList<>(); + private int _numberWhenStatements; + private TransformResultMetadata _resultMetadata; + + @Override + public String getName() { + return FUNCTION_NAME; + } + + @Override + public void init(List<TransformFunction> arguments, Map<String, DataSource> dataSourceMap) { + // Check that there are more than 1 arguments + if (arguments.size() % 2 != 1 || arguments.size() < 3) { + throw new IllegalArgumentException("At least 3 odd number of arguments are required for CASE-WHEN-ELSE function"); + } + _numberWhenStatements = arguments.size() / 2; + for (int i = 0; i < _numberWhenStatements; i++) { + _whenStatements.add(arguments.get(i)); + } + // Add ELSE Statement first + _elseThenStatements.add(arguments.get(_numberWhenStatements * 2)); + for (int i = _numberWhenStatements; i < _numberWhenStatements * 2; i++) { + _elseThenStatements.add(arguments.get(i)); + } + Preconditions.checkState(_elseThenStatements.size() == _numberWhenStatements + 1, "Missing THEN/ELSE clause in CASE statement"); + _resultMetadata = getResultMetadata(_elseThenStatements); + } + + private TransformResultMetadata getResultMetadata(List<TransformFunction> elseThenStatements) { + FieldSpec.DataType dataType = elseThenStatements.get(0).getResultMetadata().getDataType(); + for (int i = 1; i < elseThenStatements.size(); i++) { + TransformResultMetadata resultMetadata = elseThenStatements.get(i).getResultMetadata(); + if (!resultMetadata.isSingleValue()) { Review comment: Yes we can. ---------------------------------------------------------------- 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 --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org For additional commands, e-mail: commits-h...@pinot.apache.org
