content: /*
   * 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.beam.vendor.calcite.v1_40_0.org.apache.calcite.schema.Function;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.schema.TranslatableTable;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.schema.impl.TableMacroImpl;
  
  /** Beam-customized facade behind {@link Function} to address BEAM-5921. */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  class UdfImpl {
  
    private UdfImpl() {}
  
    /**
     * Creates {@link org.apache.beam.vendor.calcite.v1_40_0.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.beam.vendor.calcite.v1_40_0.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;
    }
  }
  