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 com.aliyun.odps.udf;
  
  import java.io.IOException;
  
  /**
   * 具有拉数据功能的UDTF，可以主动调用getNextRow()获取一条记录。
   * 仅在LOT中才能使用，并且有如下限制：
   * 1. 在一个stage中只能有一个StandaloneUDTF
   * 2. StandaloneUDTF在LOT的结构中不能有siblings
   */
  public abstract class StandaloneUDTF extends UDTF {
  
    private UDTFPuller puller;
  
    /**
     * 该方法由框架调用来初始化 StandaloneUDTF
     */
    public final void init(UDTFPuller puller) {
      this.puller = puller;
    }
  
    /**
     * run方法默认实现，每拉一条记录，调用一次process方法。
     *
     * @throws UDFException
     */
    public void run() throws UDFException,IOException {
      Object[] args;
      while ((args = getNextRow()) != null) {
        process(args);
      }
    }
  
    /**
     * 获取下一条记录
     *
     * @return
     */
    public final Object[] getNextRow() {
      return puller.getNextRow();
    }
  
    public final UDTFPuller getPuller() {
      return puller;
    }
  
  }
  