/*
* 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.Collection;
import java.util.Iterator;
import java.util.Map;
import org.apache.pig.EvalFunc;
import org.apache.pig.data.BagFactory;
import org.apache.pig.data.DataBag;
import org.apache.pig.data.DataType;
import org.apache.pig.data.NonSpillableDataBag;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.impl.logicalLayer.schema.Schema;
import org.apache.pig.impl.logicalLayer.schema.Schema.FieldSchema;
/**
*
* This UDF takes a Map and returns a Bag containing the values from map. <br />
* Note that output tuple contains all values, not just unique ones. <br />
* For obtaining unique values from map, use VALUESET instead. <br />
*
* <pre>
* <code>
* grunt> cat data
* [open#apache,1#2,11#2]
* [apache#hadoop,3#4,12#hadoop]
*
* grunt> a = load 'data' as (M:[]);
* grunt> b = foreach a generate VALUELIST($0);
* grunt> dump b;
* ({(apache),(2),(2)})
* ({(4),(hadoop),(hadoop)})
* </code>
* </pre>
*
*/
public class VALUELIST extends EvalFunc<DataBag> {
private static final TupleFactory TUPLE_FACTORY = TupleFactory.getInstance();
private static final BagFactory BAG_FACTORY = BagFactory.getInstance();
@SuppressWarnings("unchecked")
@Override
public DataBag exec(Tuple input) throws IOException {
if(input == null || input.size() == 0) {
return null;
}
Map<String, Object> m = null;
//Input must be of type Map. This is verified at compile time
m = (Map<String, Object>)(input.get(0));
if(m == null) {
return null;
}
Collection c = m.values();
DataBag bag = new NonSpillableDataBag(c.size());
Iterator<Object> iter = c.iterator();
while(iter.hasNext()) {
Tuple t = TUPLE_FACTORY.newTuple(iter.next());
bag.add(t);
}
return bag;
}
@Override
public Schema outputSchema(Schema input) {
FieldSchema f = null;
FieldSchema innerFieldSchema = null;
try {
f = input.getField(0);
} catch(FrontendException fe) {
throw new RuntimeException(fe);
}
if(f.type != DataType.MAP) {
throw new RuntimeException("Expected map, received schema " +DataType.findTypeName(f.type));
}
Schema s = f.schema;
if(s != null) {
Schema.FieldSchema fs = null;
try {
fs = s.getField(0);
} catch(FrontendException fe) {
throw new RuntimeException(fe);
}
if(fs != null) {
innerFieldSchema = new Schema.FieldSchema(null, fs.type);
}
} else {
innerFieldSchema = new Schema.FieldSchema(null, DataType.BYTEARRAY);
}
Schema innerSch = new Schema(innerFieldSchema);
Schema bagSchema = null;
try{
bagSchema = new Schema(new FieldSchema(null, innerSch, DataType.BAG));
} catch(FrontendException fe) {
throw new RuntimeException(fe);
}
return bagSchema;
}
@Override
public boolean allowCompileTimeCalculation() {
return true;
}
}