uk.gov.gchq.gaffer.function

Class AggregateFunction

java.lang.Object

uk.gov.gchq.gaffer.function.ConsumerFunction

uk.gov.gchq.gaffer.function.ConsumerProducerFunction

uk.gov.gchq.gaffer.function.AggregateFunction

All Implemented Interfaces:

Cloneable, Function

Direct Known Subclasses:

SimpleAggregateFunction

public abstract class AggregateFunction
extends ConsumerProducerFunction
implements Cloneable

An AggregateFunction is a ConsumerProducerFunction that reduces a number of input records to a single output of the same record type. The function will update it's internal state in response to new input records, and return the current state on request.

For example:
AggregateFunction sum = new Sum();
sum.aggregate({1}); sum.aggregate({2}); sum.aggregate({3});
Object[] state = sum.state() // state = {6}

Constructor Summary

Constructors

Constructor and Description
AggregateFunction()

Method Summary

Modifier and Type	Method and Description
abstract void	aggregate(Object[] input) Execute this AggregateFunction with an input record.
abstract void	init() Initialise the internal state of this AggregateFunction.
abstract Object[]	state()
abstract AggregateFunction	statelessClone() Create a deep copy of this AggregateFunction, with it's internal state initialised.

Methods inherited from class uk.gov.gchq.gaffer.function.ConsumerProducerFunction

equals, getOutputClasses, hashCode, toString

Methods inherited from class uk.gov.gchq.gaffer.function.ConsumerFunction

getInputClasses

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

AggregateFunction

public AggregateFunction()

Method Detail

init

public abstract void init()

Initialise the internal state of this AggregateFunction. This will normally involve setting an aggregate field back to null.

aggregate

public abstract void aggregate(Object[] input)

Execute this AggregateFunction with an input record. Input records should match the types reported by getInputClasses().

Parameters:

input - Input record.

state

public abstract Object[] state()

Returns:

Record containing the current state of this function.

statelessClone

public abstract AggregateFunction statelessClone()

Create a deep copy of this AggregateFunction, with it's internal state initialised.

Specified by:

statelessClone in interface Function

Specified by:

statelessClone in class ConsumerProducerFunction

Returns:

Initialised copy.