    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.Matcher;
    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 matched regex group.
    038 * <p/>
    039 * Note a {@code null} valued argument passed to the parser will be converted to an empty string ({@code ""}) before
    040 * the regex is applied.
    041 * <p/>
    042 * Any Object value will be coerced to a String type if type information is provided. See the
    043 * {@link cascading.tuple.type.CoercibleType} interface to control how custom Object types are converted to String
    044 * values.
    045 */
    046public class RegexGenerator extends RegexOperation<Pair<Matcher, TupleEntry>> implements Function<Pair<Matcher, TupleEntry>>
    047  {
    048  /**
    049   * Constructor RegexGenerator creates a new RegexGenerator instance.
    050   *
    051   * @param patternString of type String
    052   */
    053  @ConstructorProperties({"patternString"})
    054  public RegexGenerator( String patternString )
    055    {
    056    super( 1, Fields.size( 1 ), patternString );
    057    }
    058
    059  /**
    060   * Constructor RegexGenerator creates a new RegexGenerator instance.
    061   *
    062   * @param fieldDeclaration of type Fields
    063   * @param patternString    of type String
    064   */
    065  @ConstructorProperties({"fieldDeclaration", "patternString"})
    066  public RegexGenerator( Fields fieldDeclaration, String patternString )
    067    {
    068    super( 1, fieldDeclaration, patternString );
    069
    070    if( fieldDeclaration.size() != 1 )
    071      throw new IllegalArgumentException( "fieldDeclaration may only declare one field, was " + fieldDeclaration.print() );
    072    }
    073
    074  @Override
    075  public void prepare( FlowProcess flowProcess, OperationCall<Pair<Matcher, TupleEntry>> operationCall )
    076    {
    077    TupleEntry tupleEntry = new TupleEntry( operationCall.getDeclaredFields(), Tuple.size( 1 ) );
    078
    079    operationCall.setContext( new Pair<>( getPattern().matcher( "" ), tupleEntry ) );
    080    }
    081
    082  @Override
    083  public void operate( FlowProcess flowProcess, FunctionCall<Pair<Matcher, TupleEntry>> functionCall )
    084    {
    085    String value = functionCall.getArguments().getString( 0 );
    086
    087    if( value == null )
    088      value = "";
    089
    090    Matcher matcher = functionCall.getContext().getLhs().reset( value );
    091
    092    while( matcher.find() )
    093      {
    094      functionCall.getContext().getRhs().setString( 0, matcher.group() );
    095      functionCall.getOutputCollector().add( functionCall.getContext().getRhs() );
    096      }
    097    }
    098  }