    001/*
    002 * Copyright (c) 2007-2016 Concurrent, 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.Matcher;
    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 matched regex group.
    036 * <p/>
    037 * Note a {@code null} valued argument passed to the parser will be converted to an empty string ({@code ""}) before
    038 * the regex is applied.
    039 * <p/>
    040 * Any Object value will be coerced to a String type if type information is provided. See the
    041 * {@link cascading.tuple.type.CoercibleType} interface to control how custom Object types are converted to String
    042 * values.
    043 */
    044public class RegexGenerator extends RegexOperation<Pair<Matcher, Tuple>> implements Function<Pair<Matcher, Tuple>>
    045  {
    046  /**
    047   * Constructor RegexGenerator creates a new RegexGenerator instance.
    048   *
    049   * @param patternString of type String
    050   */
    051  @ConstructorProperties({"patternString"})
    052  public RegexGenerator( String patternString )
    053    {
    054    super( 1, Fields.size( 1 ), patternString );
    055    }
    056
    057  /**
    058   * Constructor RegexGenerator creates a new RegexGenerator instance.
    059   *
    060   * @param fieldDeclaration of type Fields
    061   * @param patternString    of type String
    062   */
    063  @ConstructorProperties({"fieldDeclaration", "patternString"})
    064  public RegexGenerator( Fields fieldDeclaration, String patternString )
    065    {
    066    super( 1, fieldDeclaration, patternString );
    067
    068    if( fieldDeclaration.size() != 1 )
    069      throw new IllegalArgumentException( "fieldDeclaration may only declare one field, was " + fieldDeclaration.print() );
    070    }
    071
    072  @Override
    073  public void prepare( FlowProcess flowProcess, OperationCall<Pair<Matcher, Tuple>> operationCall )
    074    {
    075    operationCall.setContext( new Pair<Matcher, Tuple>( getPattern().matcher( "" ), Tuple.size( 1 ) ) );
    076    }
    077
    078  @Override
    079  public void operate( FlowProcess flowProcess, FunctionCall<Pair<Matcher, Tuple>> functionCall )
    080    {
    081    String value = functionCall.getArguments().getString( 0 );
    082
    083    if( value == null )
    084      value = "";
    085
    086    Matcher matcher = functionCall.getContext().getLhs().reset( value );
    087
    088    while( matcher.find() )
    089      {
    090      functionCall.getContext().getRhs().set( 0, matcher.group() );
    091      functionCall.getOutputCollector().add( functionCall.getContext().getRhs() );
    092      }
    093    }
    094  }