org.apache.pig.builtin
Class IsEmpty
java.lang.Object
org.apache.pig.EvalFunc<Boolean>
org.apache.pig.FilterFunc
org.apache.pig.builtin.IsEmpty
- All Implemented Interfaces:
- Accumulator<Boolean>, TerminatingAccumulator<Boolean>
public class IsEmpty
- extends FilterFunc
- implements TerminatingAccumulator<Boolean>
Determine whether a bag or map is empty.
Method Summary |
void |
accumulate(Tuple b)
Pass tuples to the UDF. |
void |
cleanup()
Called after getValue() to prepare processing for next key. |
Boolean |
exec(Tuple input)
This callback method must be implemented by all subclasses. |
Boolean |
getValue()
Called when all tuples from current key have been passed to accumulate. |
boolean |
isFinished()
|
Methods inherited from class org.apache.pig.EvalFunc |
getArgToFuncMapping, getCacheFiles, getInputSchema, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, 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 |
IsEmpty
public IsEmpty()
exec
public Boolean exec(Tuple input)
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<Boolean>
- Parameters:
input
- the Tuple to be processed.
- Returns:
- result, of type T.
- Throws:
IOException
isFinished
public boolean isFinished()
- Specified by:
isFinished
in interface TerminatingAccumulator<Boolean>
accumulate
public void accumulate(Tuple b)
throws IOException
- Description copied from interface:
Accumulator
- Pass tuples to the UDF.
- Specified by:
accumulate
in interface Accumulator<Boolean>
- Parameters:
b
- A tuple containing a single field, which is a bag. The bag will contain the set
of tuples being passed to the UDF in this iteration.
- Throws:
IOException
cleanup
public void cleanup()
- Description copied from interface:
Accumulator
- Called after getValue() to prepare processing for next key.
- Specified by:
cleanup
in interface Accumulator<Boolean>
getValue
public Boolean getValue()
- Description copied from interface:
Accumulator
- Called when all tuples from current key have been passed to accumulate.
- Specified by:
getValue
in interface Accumulator<Boolean>
- Returns:
- the value for the UDF for this key.
Copyright © 2007-2012 The Apache Software Foundation