| /* |
| * 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 org.apache.calcite.schema.Function; |
| import org.apache.calcite.schema.TranslatableTable; |
| import org.apache.calcite.schema.impl.TableMacroImpl; |
| |
| /** Beam-customized facade behind {@link Function} to address BEAM-5921. */ |
| class UdfImpl { |
| |
| private UdfImpl() {} |
| |
| /** |
| * Creates {@link org.apache.calcite.schema.Function} from given class. |
| * |
| * <p>If a method of the given name is not found or it does not suit, returns {@code null}. |
| * |
| * @param clazz class that is used to implement the function |
| * @param methodName Method name (typically "eval") |
| * @return created {@link Function} or null |
| */ |
| public static Function create(Class<?> clazz, String methodName) { |
| final Method method = findMethod(clazz, methodName); |
| if (method == null) { |
| return null; |
| } |
| return create(method); |
| } |
| |
| /** |
| * Creates {@link org.apache.calcite.schema.Function} from given method. |
| * |
| * @param method method that is used to implement the function |
| * @return created {@link Function} or null |
| */ |
| public static Function create(Method method) { |
| if (TranslatableTable.class.isAssignableFrom(method.getReturnType())) { |
| return TableMacroImpl.create(method); |
| } else { |
| return ScalarFunctionImpl.create(method); |
| } |
| } |
| |
| /* |
| * Finds a method in a given class by name. |
| * @param clazz class to search method in |
| * @param name name of the method to find |
| * @return the first method with matching name or null when no method found |
| */ |
| static Method findMethod(Class<?> clazz, String name) { |
| for (Method method : clazz.getMethods()) { |
| if (method.getName().equals(name) && !method.isBridge()) { |
| return method; |
| } |
| } |
| return null; |
| } |
| } |