org.apache.pig.impl.builtin

Class ReadScalars

java.lang.Object

org.apache.pig.EvalFunc<java.lang.Object>

org.apache.pig.impl.builtin.ReadScalars

public class ReadScalars
extends EvalFunc<java.lang.Object>

ReadScalars reads a line from a file and returns it as its value. The file is only read once, and the same line is returned over and over again. This is useful for incorporating a result from an agregation into another evaluation.

Nested Class Summary

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

EvalFunc.SchemaType

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

Constructors

Constructor and Description
ReadScalars()

Method Summary

Modifier and Type	Method and Description
java.lang.Object	exec(Tuple input) Java level API
void	setOutputBuffer(java.util.Map<java.lang.String,DataBag> inputBuffer)

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

Constructor Detail

ReadScalars

public ReadScalars()

Method Detail

exec

public java.lang.Object exec(Tuple input)
                      throws java.io.IOException

Java level API

Specified by:

exec in class EvalFunc<java.lang.Object>

Parameters:

input - expects a single constant that is the name of the file to be read

Returns:

result, of type T.

Throws:

java.io.IOException

setOutputBuffer

public void setOutputBuffer(java.util.Map<java.lang.String,DataBag> inputBuffer)