/*
* 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.piggybank.evaluation.decode;
import java.io.IOException;
import org.apache.pig.EvalFunc;
import org.apache.pig.PigWarning;
import org.apache.pig.data.DataType;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.logicalLayer.schema.Schema;
/**
* <dl>
* <dt><b>Syntax:</b></dt>
* <dd><code>String Decode(expression, value1, mapping_string1, ..., valueN, mapping_stringN, other_string)</code>.</dd>
* <dt><b>Logic:</b></dt>
* <dd><code>if (expression==value1) return mapping_string1; <br>
* ...... <br>
* else if (expression==valueN) return mapping_stringN; <br>
* else return other_string;<br></code> <br>
* expression can be any simple types</dd>
* </dl>
*/
public class Decode extends EvalFunc<String> {
int numParams = -1;
@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;
}
}
@Override
public String exec(Tuple tuple) throws IOException {
if (numParams==-1) // Not initialized
{
numParams = tuple.size();
if (numParams <= 2) {
String msg = "Decode: Atleast an expression and default string is required.";
throw new IOException(msg);
}
if (tuple.size()%2!=0) {
String msg = "Decode : Some parameters are unmatched.";
throw new IOException(msg);
}
}
if (tuple.get(0)==null)
return null;
try {
for (int count = 1; count < numParams - 1; count += 2)
{
if (tuple.get(count).equals(tuple.get(0)))
{
return (String)tuple.get(count+1);
}
}
} catch (ClassCastException e) {
warn("Decode : Data type error", PigWarning.UDF_WARNING_1);
return null;
} catch (NullPointerException e) {
String msg = "Decode : Encounter null in the input";
throw new IOException(msg);
}
return (String)tuple.get(tuple.size()-1);
}
}