org.apache.pig

Class PrimitiveEvalFunc<IN,OUT>

java.lang.Object

org.apache.pig.EvalFunc<OUT>

org.apache.pig.TypedOutputEvalFunc<OUT>

org.apache.pig.PrimitiveEvalFunc<IN,OUT>

Direct Known Subclasses:

FunctionWrapperEvalFunc

public abstract class PrimitiveEvalFunc<IN,OUT>
extends TypedOutputEvalFunc<OUT>

Base class for simple Pig UDFs that are functions of primitive types IN to OUT. Handles marshalling objects, basic error checking, etc. Extend this class and implement the

OUT exec(IN input)

method when writting a UDF that operates on only the first input (of expected type IN) from the Tuple.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.pig.EvalFunc

EvalFunc.SchemaType

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.Class<IN>	inTypeClass

Fields inherited from class org.apache.pig.TypedOutputEvalFunc

outTypeClass

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

Constructors

Constructor and Description
PrimitiveEvalFunc()
PrimitiveEvalFunc(java.lang.Class inTypeClass, java.lang.Class outTypeClass)

Method Summary

Modifier and Type	Method and Description
abstract OUT	exec(IN input)
OUT	exec(Tuple tuple) This callback method must be implemented by all subclasses.
java.lang.Class<IN>	getInputTypeClass()

Methods inherited from class org.apache.pig.TypedOutputEvalFunc

getCounterGroup, getOutputTypeClass, getTypeArguments, safeIncrCounter, verifyInput, verifyUdfInput

Methods inherited from class org.apache.pig.EvalFunc

allowCompileTimeCalculation, finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLoadCaster, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, getShipFiles, isAsynchronous, needEndOfAllInputProcessing, outputSchema, progress, setEndOfAllInput, setInputSchema, setPigLogger, setReporter, setUDFContextSignature, warn

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

inTypeClass

protected java.lang.Class<IN> inTypeClass

Constructor Detail

PrimitiveEvalFunc

public PrimitiveEvalFunc()

PrimitiveEvalFunc

public PrimitiveEvalFunc(java.lang.Class inTypeClass,
                         java.lang.Class outTypeClass)

Method Detail

getInputTypeClass

public java.lang.Class<IN> getInputTypeClass()

exec

public OUT exec(Tuple tuple)
         throws java.io.IOException

Description copied from class: EvalFunc

This callback method must be implemented by all subclasses. This is the method that will be invoked on every Tuple of a given dataset. Since the dataset may be divided up in a variety of ways the programmer should not make assumptions about state that is maintained between invocations of this method.

Specified by:

exec in class EvalFunc<OUT>

Parameters:

tuple - the Tuple to be processed.

Returns:

result, of type T.

Throws:

java.io.IOException

exec

public abstract OUT exec(IN input)
                  throws java.io.IOException

Throws:

java.io.IOException