| /* |
| * 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.EvalFunc; |
| import org.apache.pig.FuncSpec; |
| 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; |
| import org.apache.pig.impl.logicalLayer.FrontendException; |
| |
| /** |
| * SUBSTRING implements eval function to get a part of a string. |
| * Example:<code> |
| * A = load 'mydata' as (name); |
| * B = foreach A generate SUBSTRING(name, 10, 12); |
| * </code> |
| * First argument is the string to take a substring of.<br> |
| * Second argument is the index of the first character of substring.<br> |
| * Third argument is the index of the last character of substring.<br> |
| * if the last argument is past the end of the string, substring of (beginIndex, length(str)) is returned. |
| */ |
| public class SUBSTRING extends EvalFunc<String> { |
| |
| /** |
| * Method invoked on every tuple during foreach evaluation |
| * @param input tuple; first column is assumed to have the column to convert |
| * @exception java.io.IOException |
| */ |
| @Override |
| public String exec(Tuple input) throws IOException { |
| if (input == null || input.size() < 3) { |
| warn("invalid number of arguments to SUBSTRING", PigWarning.UDF_WARNING_1); |
| return null; |
| } |
| try { |
| String source = (String)input.get(0); |
| Integer beginindex = (Integer)input.get(1); |
| Integer endindex = (Integer)input.get(2); |
| return source.substring(beginindex, Math.min(source.length(), endindex)); |
| } catch (NullPointerException npe) { |
| warn(npe.toString(), PigWarning.UDF_WARNING_2); |
| return null; |
| } catch (StringIndexOutOfBoundsException npe) { |
| warn(npe.toString(), PigWarning.UDF_WARNING_3); |
| return null; |
| } catch (ClassCastException e) { |
| warn(e.toString(), PigWarning.UDF_WARNING_4); |
| return null; |
| } |
| } |
| |
| @Override |
| public Schema outputSchema(Schema input) { |
| return new Schema(new Schema.FieldSchema(null, DataType.CHARARRAY)); |
| } |
| |
| /* (non-Javadoc) |
| * @see org.apache.pig.EvalFunc#getArgToFuncMapping() |
| */ |
| @Override |
| public List<FuncSpec> getArgToFuncMapping() throws FrontendException { |
| List<FuncSpec> funcList = new ArrayList<FuncSpec>(); |
| Schema s = new Schema(); |
| s.add(new Schema.FieldSchema(null, DataType.CHARARRAY)); |
| s.add(new Schema.FieldSchema(null, DataType.INTEGER)); |
| s.add(new Schema.FieldSchema(null, DataType.INTEGER)); |
| funcList.add(new FuncSpec(this.getClass().getName(), s)); |
| return funcList; |
| } |
| |
| @Override |
| public boolean allowCompileTimeCalculation() { |
| return true; |
| } |
| } |