spork-master/contrib/piggybank/java/src/main/java/org/apache/pig/piggybank/evaluation/math/SCALB.java
/*
 * 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.math;

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.data.Tuple;
import org.apache.pig.impl.logicalLayer.schema.Schema;
import org.apache.pig.data.DataType;
import org.apache.pig.impl.logicalLayer.FrontendException;

/**
 * math.SCALB implements a binding to the Java function
* {@link java.lang.Math#scalb(double,int) Math.scalb(double,int)}. 
* Given a tuple with two data atom x and y ,it Return x pow(2,y) 
* rounded as if performed by a single correctly rounded 
* floating-point multiply to a member of the double value set.
* 
* <dl>
* <dt><b>Parameters:</b></dt>
* <dd><code>value</code> - <code>Tuple containing two numeric values [Double, Integer]</code>.</dd>
* 
* <dt><b>Return Value:</b></dt>
* <dd><code>Double</code> </dd>
* 
* <dt><b>Return Schema:</b></dt>
* <dd>SCALB_inputSchema</dd>
* 
* <dt><b>Example:</b></dt>
* <dd><code>
* register math.jar;<br/>
* A = load 'mydata' using PigStorage() as ( float1 );<br/>
* B = foreach A generate float1, math.SCALB(float1);
* </code></dd>
* </dl>
* 
* @see Math#scalb(double,int)
* @see
* @author ajay garg
*
*/
public class SCALB extends EvalFunc<Double>{
	
	/**
	 * java level API
	 * @param input expects a tuple containing two numeric DataAtom value
	 * @param output returns a single numeric DataAtom value, which is 
	 * fistArgument pow(2,secondArgument) rounded as if performed by a 
	 * single correctly rounded floating-point multiply to a member of 
	 * the double value set.
	 */
	public Double exec(Tuple input) throws IOException {
        if (input == null || input.size() < 2)
            return null;
        if (input.get(0) == null || input.get(1) == null) {
            return null;
        }
		try{
			Double first = DataType.toDouble(input.get(0));
			Integer second = DataType.toInteger(input.get(1));

            return Math.scalb(first, second);
		} catch (NumberFormatException nfe){
            System.err.println("Failed to process input; error - " + nfe.getMessage());
            return null;
        } catch(Exception e){
            throw new IOException("Caught exception in MAX.Initial", e);
        }
	}
	
	@Override
	public Schema outputSchema(Schema input) {
        return new Schema(new Schema.FieldSchema(getSchemaName(this.getClass().getName().toLowerCase(), input), DataType.DOUBLE));
	}

    /* (non-Javadoc)
     * @see org.apache.pig.EvalFunc#getArgToFuncMapping()
     */
    @Override
    public List<FuncSpec> getArgToFuncMapping() throws FrontendException {
        List<FuncSpec> funcList = new ArrayList<FuncSpec>();
        Util.addToFunctionList(funcList, this.getClass().getName(), DataType.BYTEARRAY);
        Util.addToFunctionList(funcList, DoubleMax.class.getName(), DataType.DOUBLE);
        Util.addToFunctionList(funcList, FloatMax.class.getName(), DataType.FLOAT);

        return funcList;
   }
}
