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/*
 * 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 com.hazelcast.org.apache.calcite.model;

import com.hazelcast.com.fasterxml.jackson.annotation.JsonCreator;
import com.hazelcast.com.fasterxml.jackson.annotation.JsonProperty;

import com.hazelcast.org.checkerframework.checker.nullness.qual.Nullable;

import java.util.List;

import static java.util.Objects.requireNonNull;

/**
 * Function schema element.
 *
 * @see JsonRoot Description of schema elements
 */
public class JsonFunction {
  /** Name of this function.
   *
   * Required.
   */
  public final String name;

  /** Name of the class that implements this function.
   *
   * 
Required.
   */
  public final String className;

  /** Name of the method that implements this function.
   *
   * 
Optional.
   *
   * 
If specified, the method must exist (case-sensitive) and Calcite
   * will create a scalar function. The method may be static or non-static, but
   * if non-static, the class must have a public constructor with no parameters.
   *
   * 
If "*", Calcite creates a function for every method
   * in this class.
   *
   * 
If not specified, Calcite looks for a method called "eval", and
   * if found, creates a a table macro or scalar function.
   * It also looks for methods "init", "add", "merge", "result", and
   * if found, creates an aggregate function.
   */
  public final @Nullable String methodName;

  /** Path for resolving this function.
   *
   * Optional.
   */
  public final @Nullable List path;

  @JsonCreator
  public JsonFunction(
      @JsonProperty("name") String name,
      @JsonProperty(value = "className", required = true) String className,
      @JsonProperty("methodName") @Nullable String methodName,
      @JsonProperty("path") @Nullable List path) {
    this.name = name;
    this.className = requireNonNull(className, "className");
    this.methodName = methodName;
    this.path = path;
  }

  public void accept(ModelHandler handler) {
    handler.visit(this);
  }
}