    001/*
    002 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved.
    003 *
    004 * Project and contact information: http://www.cascading.org/
    005 *
    006 * This file is part of the Cascading project.
    007 *
    008 * Licensed under the Apache License, Version 2.0 (the "License");
    009 * you may not use this file except in compliance with the License.
    010 * You may obtain a copy of the License at
    011 *
    012 *     http://www.apache.org/licenses/LICENSE-2.0
    013 *
    014 * Unless required by applicable law or agreed to in writing, software
    015 * distributed under the License is distributed on an "AS IS" BASIS,
    016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    017 * See the License for the specific language governing permissions and
    018 * limitations under the License.
    019 */
    020
    021package cascading.operation.regex;
    022
    023import java.beans.ConstructorProperties;
    024import java.util.regex.Pattern;
    025
    026import cascading.flow.FlowProcess;
    027import cascading.operation.Function;
    028import cascading.operation.FunctionCall;
    029import cascading.operation.OperationCall;
    030import cascading.tuple.Fields;
    031import cascading.tuple.Tuple;
    032import cascading.util.Pair;
    033
    034/**
    035 * Class RegexGenerator will emit a new Tuple for every split on the incoming argument value delimited by the given patternString.
    036 * <p/>
    037 * RegexGenerator only expects one field value. If more than one argument value is passed, only the
    038 * first is handled, the remainder are ignored.
    039 * <p/>
    040 * This could be used to break a document into single word tuples for later processing for a word count.
    041 * <p/>
    042 * Note a {@code null} valued argument passed to the parser will be converted to an empty string ({@code ""}) before
    043 * the regex is applied.
    044 * <p/>
    045 * Any Object value will be coerced to a String type if type information is provided. See the
    046 * {@link cascading.tuple.type.CoercibleType} interface to control how custom Object types are converted to String
    047 * values.
    048 */
    049public class RegexSplitGenerator extends RegexOperation<Pair<Pattern, Tuple>> implements Function<Pair<Pattern, Tuple>>
    050  {
    051  /**
    052   * Constructor RegexGenerator creates a new RegexGenerator instance.
    053   *
    054   * @param patternString of type String
    055   */
    056  @ConstructorProperties({"patternString"})
    057  public RegexSplitGenerator( String patternString )
    058    {
    059    super( 1, Fields.size( 1 ), patternString );
    060    }
    061
    062  /**
    063   * Constructor RegexGenerator creates a new RegexGenerator instance.
    064   *
    065   * @param fieldDeclaration of type Fields
    066   * @param patternString    of type String
    067   */
    068  @ConstructorProperties({"fieldDeclaration", "patternString"})
    069  public RegexSplitGenerator( Fields fieldDeclaration, String patternString )
    070    {
    071    super( 1, fieldDeclaration, patternString );
    072
    073    if( fieldDeclaration.size() != 1 )
    074      throw new IllegalArgumentException( "fieldDeclaration may only declare one field, was " + fieldDeclaration.print() );
    075    }
    076
    077  @Override
    078  public void prepare( FlowProcess flowProcess, OperationCall<Pair<Pattern, Tuple>> operationCall )
    079    {
    080    operationCall.setContext( new Pair<Pattern, Tuple>( getPattern(), Tuple.size( 1 ) ) );
    081    }
    082
    083  @Override
    084  public void operate( FlowProcess flowProcess, FunctionCall<Pair<Pattern, Tuple>> functionCall )
    085    {
    086    String value = functionCall.getArguments().getString( 0 );
    087
    088    if( value == null )
    089      value = "";
    090
    091    String[] split = functionCall.getContext().getLhs().split( value );
    092
    093    for( String string : split )
    094      {
    095      functionCall.getContext().getRhs().set( 0, string );
    096      functionCall.getOutputCollector().add( functionCall.getContext().getRhs() );
    097      }
    098    }
    099  }