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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.tutorial;
import java.io.IOException;
import java.util.List;
import java.util.ArrayList;
import org.apache.pig.EvalFunc;
import org.apache.pig.FuncSpec;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.DataType;
import org.apache.pig.impl.logicalLayer.schema.Schema;
import org.apache.pig.impl.logicalLayer.FrontendException;
/**
* This function converts the input into lowercase and
* removes leading and trailing white spaces.
*/
public class ToLower extends EvalFunc<String> {
public String exec(Tuple input) throws IOException {
if(input == null || input.size() == 0)
return null;
try{
String query = (String)input.get(0);
return query.toLowerCase().trim();
}catch(Exception e){
System.err.println("ToLower: failed to process input; error - " + e.getMessage());
return null;
}
}
@Override
/**
* This method gives a name to the column.
* @param input - schema of the input data
* @return schema of the output data
*/
public Schema outputSchema(Schema input) {
return new Schema(new Schema.FieldSchema(getSchemaName(this.getClass().getName().toLowerCase(), input), DataType.CHARARRAY));
}
/* (non-Javadoc)
* @see org.apache.pig.EvalFunc#getArgToFuncMapping()
* This is needed to make sure that both bytearrays and chararrays can be passed as arguments
*/
@Override
public List<FuncSpec> getArgToFuncMapping() throws FrontendException {
List<FuncSpec> funcList = new ArrayList<FuncSpec>();
funcList.add(new FuncSpec(this.getClass().getName(), new Schema(new Schema.FieldSchema(null, DataType.CHARARRAY))));
return funcList;
}
}