    001/*
    002 * Copyright (c) 2016-2017 Chris K Wensel. All Rights Reserved.
    003 * Copyright (c) 2007-2017 Xplenty, Inc. All Rights Reserved.
    004 *
    005 * Project and contact information: http://www.cascading.org/
    006 *
    007 * This file is part of the Cascading project.
    008 *
    009 * Licensed under the Apache License, Version 2.0 (the "License");
    010 * you may not use this file except in compliance with the License.
    011 * You may obtain a copy of the License at
    012 *
    013 *     http://www.apache.org/licenses/LICENSE-2.0
    014 *
    015 * Unless required by applicable law or agreed to in writing, software
    016 * distributed under the License is distributed on an "AS IS" BASIS,
    017 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    018 * See the License for the specific language governing permissions and
    019 * limitations under the License.
    020 */
    021
    022package cascading.operation.regex;
    023
    024import java.beans.ConstructorProperties;
    025import java.util.regex.Pattern;
    026
    027import cascading.flow.FlowProcess;
    028import cascading.operation.Function;
    029import cascading.operation.FunctionCall;
    030import cascading.operation.OperationCall;
    031import cascading.tuple.Fields;
    032import cascading.tuple.Tuple;
    033import cascading.tuple.TupleEntry;
    034import cascading.util.Pair;
    035
    036/**
    037 * Class RegexGenerator will emit a new Tuple for every split on the incoming argument value delimited by the given patternString.
    038 * <p/>
    039 * RegexGenerator only expects one field value. If more than one argument value is passed, only the
    040 * first is handled, the remainder are ignored.
    041 * <p/>
    042 * This could be used to break a document into single word tuples for later processing for a word count.
    043 * <p/>
    044 * Note a {@code null} valued argument passed to the parser will be converted to an empty string ({@code ""}) before
    045 * the regex is applied.
    046 * <p/>
    047 * Any Object value will be coerced to a String type if type information is provided. See the
    048 * {@link cascading.tuple.type.CoercibleType} interface to control how custom Object types are converted to String
    049 * values.
    050 */
    051public class RegexSplitGenerator extends RegexOperation<Pair<Pattern, TupleEntry>> implements Function<Pair<Pattern, TupleEntry>>
    052  {
    053  /**
    054   * Constructor RegexGenerator creates a new RegexGenerator instance.
    055   *
    056   * @param patternString of type String
    057   */
    058  @ConstructorProperties({"patternString"})
    059  public RegexSplitGenerator( String patternString )
    060    {
    061    super( 1, Fields.size( 1 ), patternString );
    062    }
    063
    064  /**
    065   * Constructor RegexGenerator creates a new RegexGenerator instance.
    066   *
    067   * @param fieldDeclaration of type Fields
    068   * @param patternString    of type String
    069   */
    070  @ConstructorProperties({"fieldDeclaration", "patternString"})
    071  public RegexSplitGenerator( Fields fieldDeclaration, String patternString )
    072    {
    073    super( 1, fieldDeclaration, patternString );
    074
    075    if( fieldDeclaration.size() != 1 )
    076      throw new IllegalArgumentException( "fieldDeclaration may only declare one field, was " + fieldDeclaration.print() );
    077    }
    078
    079  @Override
    080  public void prepare( FlowProcess flowProcess, OperationCall<Pair<Pattern, TupleEntry>> operationCall )
    081    {
    082    TupleEntry tupleEntry = new TupleEntry( operationCall.getDeclaredFields(), Tuple.size( 1 ) );
    083
    084    operationCall.setContext( new Pair<>( getPattern(), tupleEntry ) );
    085    }
    086
    087  @Override
    088  public void operate( FlowProcess flowProcess, FunctionCall<Pair<Pattern, TupleEntry>> functionCall )
    089    {
    090    String value = functionCall.getArguments().getString( 0 );
    091
    092    if( value == null )
    093      value = "";
    094
    095    String[] split = functionCall.getContext().getLhs().split( value );
    096
    097    for( String string : split )
    098      {
    099      TupleEntry tupleEntry = functionCall.getContext().getRhs();
    100
    101      tupleEntry.setString( 0, string );
    102      functionCall.getOutputCollector().add( tupleEntry );
    103      }
    104    }
    105  }