slinkydeveloper commented on a change in pull request #17522: URL: https://github.com/apache/flink/pull/17522#discussion_r737499573
########## File path: flink-table/flink-table-planner/src/main/java/org/apache/flink/table/planner/functions/casting/rules/AbstractNullAwareCodeGeneratorCastRule.java ########## @@ -0,0 +1,91 @@ +/* + * 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.flink.table.planner.functions.casting.rules; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.table.planner.functions.casting.CastCodeBlock; +import org.apache.flink.table.planner.functions.casting.CastRulePredicate; +import org.apache.flink.table.planner.functions.casting.CodeGeneratorCastRule; +import org.apache.flink.table.types.logical.LogicalType; + +/** + * Base class for cast rules supporting code generation. This class inherits from {@link + * AbstractCodeGeneratorCastRule} and takes care of nullability checks. + */ +@Internal +public abstract class AbstractNullAwareCodeGeneratorCastRule<IN, OUT> + extends AbstractCodeGeneratorCastRule<IN, OUT> { + + protected AbstractNullAwareCodeGeneratorCastRule(CastRulePredicate predicate) { + super(predicate); + } + + /** + * This method doesn't need to take care of null checks handling of input values. + * Implementations should write the cast result in the {@code returnVariable}. + */ + protected abstract String generateCodeBlockInternal( + CodeGeneratorCastRule.Context context, + String inputTerm, + String returnVariable, + LogicalType inputLogicalType, + LogicalType targetLogicalType); + + @Override + public CastCodeBlock generateCodeBlock( + CodeGeneratorCastRule.Context context, + String inputTerm, + LogicalType inputType, + LogicalType targetType) { + StringBuilder resultCode = new StringBuilder(); + + // Result of a casting can be null only and only if the input is null + boolean isResultNullable = inputType.isNullable(); + String nullTerm; + if (isResultNullable) { + nullTerm = context.declareVariable("boolean", "isNull"); + resultCode.append(nullTerm).append(" = ").append(inputTerm).append(" == null;\n"); + } else { + nullTerm = "false"; + } + + // Create the result value variable + String returnTerm = context.declareVariable(targetType, "result"); + + // Generate the code block + String castCodeBlock = + this.generateCodeBlockInternal( + context, inputTerm, returnTerm, inputType, targetType); + + if (isResultNullable) { + resultCode + .append("if (!") Review comment: I don't understand what's your suggestion here, should we keep all `+` or `StringBuilder`? I personally just tried to use whatever fits best, but I'm ok if we wanna decide for trying to stick to a precise code style. -- 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. To unsubscribe, e-mail: issues-unsubscr...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
