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/*
 * Copyright © 2016 Cask Data, Inc.
 *
 * Licensed 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 co.cask.wrangler.api;

import co.cask.wrangler.api.annotations.PublicEvolving;

import java.io.Serializable;

/**
 * A interface defining the wrangle Executor in the wrangling {@link RecipePipeline}.
 */
@PublicEvolving
public interface Executor extends Serializable {
  /**
   * This method provides a way for the custom directive writer the ability to access
   * the arguments passed by the users.
   *
   * 

This method is invoked only once during the initialization phase of the {@code Executor} * object. The arguments are constructed based on the definition as provided by the user in * the method above {@code define}.

* *

* Following is an example of how {@code initialize} could be used to accept the * arguments that are tokenized and parsed by the framework. * * public void initialize(Arguments args) throws DirectiveParseException { * ColumnName column = args.value("column"); * if (args.contains("number") { * Numeric number = args.value("number"); * } * Text text = args.value("text"); * Bool bool = args.value("boolean"); * Expression expression = args.value("expression"); * } * *

* * @param args Tokenized and parsed arguments. * @throws DirectiveParseException thrown by the user in case of any issues with validation or * ensuring the argument values are as expected. */ void initialize(Arguments args) throws DirectiveParseException; /** * Executes a wrangle step on single {@link Row} and return an array of wrangled {@link Row}. * * @param rows List of input {@link Row} to be wrangled by this step. * @param context {@link ExecutorContext} passed to each step. * @return Wrangled List of {@link Row}. */ O execute(I rows, ExecutorContext context) throws DirectiveExecutionException, ErrorRowException, ReportErrorAndProceed; /** * This method provides a way for the directive to de-initialize or destroy the * resources that were acquired during the initialization phase. This method is * called from the Transform#destroy() when the directive is invoked * within a plugin or when during Service#destroy() when invoked in the * service. * * This method is specifically designed not to thrown any exceptions. So, if the * the user code is throws any exception, the system will be unable to react or * correct at this phase of invocation. */ void destroy(); }




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