Hisoka-X commented on code in PR #4241: URL: https://github.com/apache/flink-cdc/pull/4241#discussion_r2754354903
########## flink-cdc-runtime/src/main/java/org/apache/flink/cdc/runtime/functions/impl/StructFunctions.java: ########## @@ -0,0 +1,96 @@ +/* + * 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.cdc.runtime.functions.impl; + +import java.util.List; +import java.util.Map; + +/** Struct built-in functions. */ +public class StructFunctions { + + /** + * Accesses an element from an ARRAY or MAP by index or key. + * + * <p>For ARRAY: Uses 1-based index (SQL standard). array[1] returns the first element. + * + * <p>For MAP: Uses key to access the value. map['key'] returns the value for 'key'. + */ + public static Object itemAccess(Object collection, Object indexOrKey) { + if (collection == null || indexOrKey == null) { + return null; + } + + Object result; + if (collection instanceof List) { + result = arrayElement((List) collection, indexOrKey); + } else if (collection instanceof Map) { + result = mapValue((Map<?, ?>) collection, indexOrKey); + } else { + throw new IllegalArgumentException( + "itemAccess only supports List or Map, but got: " + + collection.getClass().getName()); + } + return result; + } + + /** + * Gets an element from an Object array by index (1-based, SQL standard). This overload handles + * arrays that have been converted from ArrayData to Object[] by DataTypeConverter. + * + * @param array the Object array to access + * @param index the 1-based index + * @return the element at the specified index, or null if index is out of bounds + */ + public static Object arrayElement(List array, Object index) { + if (array == null || index == null) { + return null; + } + + int idx; + if (index instanceof Number) { + idx = ((Number) index).intValue(); + } else { + idx = Integer.parseInt(index.toString()); + } + + // Convert 1-based index to 0-based (SQL standard uses 1-based indexing) + int zeroBasedIndex = idx - 1; + + // Check bounds + if (zeroBasedIndex < 0 || zeroBasedIndex >= array.size()) { + return null; + } + + return array.get(zeroBasedIndex); + } + + /** + * Gets a value from a Map by key. + * + * @param map the Map to access + * @param key the key to look up + * @return the value for the specified key, or null if not found + */ + public static Object mapValue(Map<?, ?> map, Object key) { Review Comment: I prefer support with another pr cause variant type behavior is different in calcite. We need add some custom operator. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
