| /* |
| * 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.Map; |
| |
| import org.apache.pig.EvalFunc; |
| 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 keyset. <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 KEYSET($0); |
| * grunt> dump b; |
| * ({(open),(1),(11)}) |
| * ({(3),(apache),(12)}) |
| * </code> |
| * </pre> |
| */ |
| public class KEYSET extends EvalFunc<DataBag> { |
| private static final TupleFactory TUPLE_FACTORY = TupleFactory.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; |
| } |
| |
| DataBag bag = new NonSpillableDataBag(m.size()); |
| for (String s : m.keySet()) { |
| Tuple t = TUPLE_FACTORY.newTuple(s); |
| bag.add(t); |
| } |
| |
| return bag; |
| } |
| |
| @Override |
| public Schema outputSchema(Schema input) { |
| try { |
| if(input.getField(0).type != DataType.MAP) { |
| throw new RuntimeException("Expected map, received schema " +DataType.findTypeName(input.getField(0).type)); |
| } |
| } catch(FrontendException e) { |
| throw new RuntimeException(e); |
| } |
| |
| FieldSchema innerFieldSchema = new Schema.FieldSchema(null, DataType.CHARARRAY); |
| Schema innerSchema = new Schema(innerFieldSchema); |
| Schema bagSchema = null; |
| |
| try { |
| bagSchema = new Schema(new FieldSchema(null, innerSchema, DataType.BAG)); |
| } catch(FrontendException e) { |
| throw new RuntimeException(e); |
| } |
| return bagSchema; |
| |
| } |
| |
| @Override |
| public boolean allowCompileTimeCalculation() { |
| return true; |
| } |
| } |