org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect

Class AggregateStep<S>

java.lang.Object

org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep<S,S>

org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.AggregateStep<S>

All Implemented Interfaces:

Serializable, Cloneable, Iterator<Traverser.Admin<S>>, Step<S,S>, Barrier<TraverserSet<S>>, ByModulating, Generating<Collection,Collection>, LocalBarrier<S>, MemoryComputing<TraverserSet<S>>, SideEffectCapable<Collection,Collection>, TraversalParent

public final class AggregateStep<S>
extends AbstractStep<S,S>
implements SideEffectCapable<Collection,Collection>, TraversalParent, ByModulating, LocalBarrier<S>

Author:

Marko A. Rodriguez (http://markorodriguez.com)

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep

id, labels, nextEnd, nextStep, previousStep, starts, traversal, traverserStepIdAndLabelsSetByChild

Constructor Summary

Constructors

Constructor and Description
AggregateStep(Traversal.Admin traversal, String sideEffectKey)

Method Summary

Modifier and Type	Method and Description
void	addBarrier(TraverserSet<S> barrier) Add a barrier to the step.
AggregateStep<S>	clone() Cloning is used to duplicate steps for the purpose of traversal optimization and OLTP replication.
List<Traversal.Admin<S,Object>>	getLocalChildren()
Set<TraverserRequirement>	getRequirements() Provide the necessary TraverserRequirement that must be met by the traverser in order for the step to function properly.
String	getSideEffectKey() The side-effect key of the step.
int	hashCode()
boolean	hasNextBarrier() Whether or not the step has an accessible barrier.
void	modulateBy(Traversal.Admin<?,?> aggregateTraversal)
TraverserSet<S>	nextBarrier() Get the next barrier within this step.
void	processAllStarts() Process all left traversers by do not yield the resultant output.
protected Traverser.Admin<S>	processNextStart()
void	reset() Reset the state of the step such that it has no incoming starts.
void	setTraversal(Traversal.Admin<?,?> parentTraversal) Set the Traversal that this step is contained within.
String	toString()

Methods inherited from class org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep

addLabel, addStart, addStarts, equals, getId, getLabels, getNextStep, getPreviousStep, getTraversal, hasNext, next, removeLabel, setId, setNextStep, setPreviousStep

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.tinkerpop.gremlin.process.traversal.step.Generating

generateFinalResult

Methods inherited from interface org.apache.tinkerpop.gremlin.process.traversal.step.TraversalParent

addGlobalChild, addLocalChild, asStep, getGlobalChildren, getSelfAndChildRequirements, integrateChild, removeGlobalChild, removeLocalChild

Methods inherited from interface org.apache.tinkerpop.gremlin.process.traversal.step.ByModulating

modulateBy, modulateBy, modulateBy, modulateBy, modulateBy, modulateBy, modulateBy, modulateBy, modulateBy, modulateBy, modulateBy

Methods inherited from interface org.apache.tinkerpop.gremlin.process.traversal.step.LocalBarrier

getMemoryComputeKey

Methods inherited from interface org.apache.tinkerpop.gremlin.process.traversal.step.Barrier

done

Methods inherited from interface org.apache.tinkerpop.gremlin.process.traversal.Step

equals

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

Constructor Detail

AggregateStep

public AggregateStep(Traversal.Admin traversal,
                     String sideEffectKey)

Method Detail

getSideEffectKey

public String getSideEffectKey()

Description copied from interface: SideEffectCapable

The side-effect key of the step.

Specified by:

getSideEffectKey in interface SideEffectCapable<Collection,Collection>

Returns:

the side-effect key

toString

public String toString()

Overrides:

toString in class AbstractStep<S,S>

modulateBy

public void modulateBy(Traversal.Admin<?,?> aggregateTraversal)

Specified by:

modulateBy in interface ByModulating

getLocalChildren

public List<Traversal.Admin<S,Object>> getLocalChildren()

Specified by:

getLocalChildren in interface TraversalParent

getRequirements

public Set<TraverserRequirement> getRequirements()

Description copied from interface: Step

Provide the necessary TraverserRequirement that must be met by the traverser in order for the step to function properly. The provided default implements returns an empty set.

Specified by:

getRequirements in interface Step<S,S>

Returns:

the set of requirements

clone

public AggregateStep<S> clone()

Description copied from interface: Step

Cloning is used to duplicate steps for the purpose of traversal optimization and OLTP replication. When cloning a step, it is important that the steps, the cloned step is equivalent to the state of the step when reset() is called. Moreover, the previous and next steps should be set to EmptyStep.

Specified by:

clone in interface Step<S,S>

Overrides:

clone in class AbstractStep<S,S>

Returns:

The cloned step

setTraversal

public void setTraversal(Traversal.Admin<?,?> parentTraversal)

Description copied from interface: Step

Set the Traversal that this step is contained within.

Specified by:

setTraversal in interface Step<S,S>

Overrides:

setTraversal in class AbstractStep<S,S>

Parameters:

parentTraversal - the new traversal for this step

hashCode

public int hashCode()

Overrides:

hashCode in class AbstractStep<S,S>

processNextStart

protected Traverser.Admin<S> processNextStart()

Specified by:

processNextStart in class AbstractStep<S,S>

processAllStarts

public void processAllStarts()

Description copied from interface: Barrier

Process all left traversers by do not yield the resultant output. This method is useful for steps like ReducingBarrierStep, where traversers can be processed "on the fly" and thus, reduce memory consumption.

Specified by:

processAllStarts in interface Barrier<TraverserSet<S>>

hasNextBarrier

public boolean hasNextBarrier()

Description copied from interface: Barrier

Whether or not the step has an accessible barrier.

Specified by:

hasNextBarrier in interface Barrier<TraverserSet<S>>

Returns:

whether a barrier exists or not

nextBarrier

public TraverserSet<S> nextBarrier()
                            throws NoSuchElementException

Description copied from interface: Barrier

Get the next barrier within this step. Barriers from parallel steps can be the be merged to create a single step with merge barriers.

Specified by:

nextBarrier in interface Barrier<TraverserSet<S>>

Returns:

the next barrier of the step

Throws:

NoSuchElementException

addBarrier

public void addBarrier(TraverserSet<S> barrier)

Description copied from interface: Barrier

Add a barrier to the step. This typically happens when multiple parallel barriers need to become one barrier at a single step.

Specified by:

addBarrier in interface Barrier<TraverserSet<S>>

Parameters:

barrier - the barrier to merge in

reset

public void reset()

Description copied from interface: Step

Reset the state of the step such that it has no incoming starts. Internal states are to be reset, but any sideEffect data structures are not to be recreated.

Specified by:

reset in interface Step<S,S>

Overrides:

reset in class AbstractStep<S,S>