ibzib commented on a change in pull request #13593: URL: https://github.com/apache/beam/pull/13593#discussion_r547566487
########## File path: sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/ScalarFnReflector.java ########## @@ -0,0 +1,73 @@ +/* + * 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.beam.sdk.extensions.sql.impl; + +import java.lang.reflect.Method; +import java.lang.reflect.Modifier; +import java.util.Arrays; +import java.util.Collection; +import org.apache.beam.sdk.extensions.sql.udf.ScalarFn; +import org.apache.beam.sdk.util.common.ReflectHelpers; + +/** Reflection-based implementation logic for {@link ScalarFn}. */ +public class ScalarFnReflector { + /** + * Gets the method annotated with {@link + * org.apache.beam.sdk.extensions.sql.udf.ScalarFn.ApplyMethod} from {@code scalarFn}. + * + * <p>There must be exactly one method annotated with {@link + * org.apache.beam.sdk.extensions.sql.udf.ScalarFn.ApplyMethod}, and it must be public. + */ + public static Method getApplyMethod(ScalarFn scalarFn) { + Class<? extends ScalarFn> clazz = scalarFn.getClass(); + Collection<Method> matches = + ReflectHelpers.declaredMethodsWithAnnotation( + ScalarFn.ApplyMethod.class, clazz, ScalarFn.class); + + if (matches.isEmpty()) { + throw new IllegalArgumentException( + String.format( + "No method annotated with @%s found in class %s.", + ScalarFn.ApplyMethod.class.getSimpleName(), clazz.getName())); + } + + // If we have at least one match, then either it should be the only match Review comment: Added tests. ---------------------------------------------------------------- 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: [email protected]
