| /* |
| * 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.List; |
| import java.util.ArrayList; |
| |
| import org.apache.pig.impl.logicalLayer.FrontendException; |
| import org.apache.pig.FuncSpec; |
| import org.apache.pig.data.Tuple; |
| import org.apache.pig.impl.logicalLayer.schema.Schema; |
| import org.apache.pig.data.DataType; |
| |
| /** |
| * base class for math udfs that return Double value |
| */ |
| public abstract class DoubleBase extends Base{ |
| // each derived class provides the computation here |
| abstract Double compute(Double input); |
| |
| /** |
| * java level API |
| * @param input expects a tuple with a single Double value |
| * @return output returns a Double value |
| */ |
| public Double exec(Tuple input) throws IOException { |
| if (input == null || input.size() == 0) |
| return null; |
| |
| try { |
| Double val = (Double)input.get(0); |
| return (val == null ? null : compute(val)); |
| } catch (Exception e){ |
| throw new IOException("Caught exception processing input of " + this.getClass().getName(), e); |
| } |
| } |
| |
| /* (non-Javadoc) |
| * @see org.apache.pig.EvalFunc#getArgToFuncMapping() |
| */ |
| @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.DOUBLE)))); |
| |
| return funcList; |
| } |
| |
| } |