slinkydeveloper commented on a change in pull request #17522: URL: https://github.com/apache/flink/pull/17522#discussion_r733701740
########## File path: flink-table/flink-table-common/src/main/java/org/apache/flink/table/data/casting/CastRule.java ########## @@ -0,0 +1,60 @@ +/* + * 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.data.casting; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.table.types.logical.LogicalType; + +import java.time.ZoneId; + +/** + * Casting executor factory performs the pre-flight of a casting operation. + * + * @param <IN> Input internal type + * @param <OUT> Output internal type + */ +@Internal +public interface CastRule<IN, OUT> { + + /** @see CastRulePredicate for more details about a cast rule predicate definition */ + CastRulePredicate getPredicateDefinition(); + + /** + * Create a casting executor starting from the provided input type. The returned {@link + * CastExecutor} assumes the input value is using the internal data type, and it's a valid value + * for the provided {@code targetLogicalType}. + */ + CastExecutor<IN, OUT> create( Review comment: `CastRuleProvider` rule resolver tries to use first `LogicalTypeRoot` for matching, then `LogicalTypeFamily` and then, if nothing matches, it uses as last resort to match predicates on the instances of `LogicalType` itself. `CastRule` needs the instances of `LogicalType` because either the code generated expression and the `CastExecutor` depends on parameters inside `LogicalType` (e.g. timestamp precision). > isn't this redundant? the CastRuleProvider can directly return the CastExecutor and we would save an additional indirection. We could convert the CastRuleProvider into a CastExecutorProvider that would only work with CastRules internally. Not really, because if you look into the `ScalarOperatorGens` changes you see how depending on which interface the `CastRule` implements, I decide how to generate code https://github.com/apache/flink/pull/17522/commits/68acfefe511801125154e10cf53a05c5f2a83fd8#diff-7f639dba805e67cebeeb8b3cba3625477c82929ffc74980dede1209ce1692155R922. -- 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
