
org.apache.pig.builtin.REGEX_EXTRACT Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.pig.builtin;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.pig.EvalFunc;
import org.apache.pig.FuncSpec;
import org.apache.pig.PigWarning;
import org.apache.pig.data.DataType;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.impl.logicalLayer.schema.Schema;
/**
*
* - Syntax:
* String RegexExtract(String expression, String regex, int match_index)
.
* - Input:
* expression
-source string
.
* regex
-regular expression
.
* match_index
-index of the group to extract
.
* - Output:
* extracted group, if fail, return null
.
*
*/
public class REGEX_EXTRACT extends EvalFunc {
String mExpression = null;
Pattern mPattern = null;
@Override
public Schema outputSchema(Schema input) {
try {
return new Schema(new Schema.FieldSchema(getSchemaName(this.getClass().getName().toLowerCase(), input), DataType.CHARARRAY));
} catch (Exception e) {
return null;
}
}
public String exec(Tuple input) throws IOException {
if (input.size()!=3) {
String msg = "RegexExtract : Only 3 parameters are allowed.";
throw new IOException(msg);
}
if (input.get(0)==null)
return null;
try {
if (!input.get(1).equals(mExpression))
{
try
{
mExpression = (String)input.get(1);
mPattern = Pattern.compile(mExpression);
} catch (Exception e)
{
String msg = "RegexExtract : Mal-Formed Regular expression : "+input.get(1);
throw new IOException(msg);
}
}
} catch (NullPointerException e) {
String msg = "RegexExtract : Regular expression is null";
throw new IOException(msg);
}
int mIndex = (Integer)input.get(2);
Matcher m = mPattern.matcher((String)input.get(0));
if (m.find()&&m.groupCount()>=mIndex)
{
return m.group(mIndex);
}
warn("RegexExtract : Cannot extract group for input "+input.get(0), PigWarning.UDF_WARNING_1);
return null;
}
@Override
public List getArgToFuncMapping() throws FrontendException {
List funcList = new ArrayList();
Schema s = new Schema();
s.add(new Schema.FieldSchema(null, DataType.CHARARRAY));
s.add(new Schema.FieldSchema(null, DataType.CHARARRAY));
s.add(new Schema.FieldSchema(null, DataType.INTEGER));
funcList.add(new FuncSpec(this.getClass().getName(), s));
return funcList;
}
}
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