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

protected 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

PrimitiveEvalFunc()

PrimitiveEvalFunc(Class inTypeClass, Class outTypeClass)

Method Summary

abstract OUT	exec(IN input)
OUT	exec(Tuple tuple) This callback method must be implemented by all subclasses.
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

finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, getSchemaType, isAsynchronous, outputSchema, progress, 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 Class<IN> inTypeClass

Constructor Detail

PrimitiveEvalFunc

public PrimitiveEvalFunc()

PrimitiveEvalFunc

public PrimitiveEvalFunc(Class inTypeClass,
                         Class outTypeClass)

Method Detail

getInputTypeClass

public Class<IN> getInputTypeClass()

exec

public OUT exec(Tuple tuple)
         throws 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:

IOException

exec

public abstract OUT exec(IN input)
                  throws IOException

Throws:

IOException