com.tinkerpop.gremlin.process.util

Class EmptyStep<S,E>

java.lang.Object

com.tinkerpop.gremlin.process.util.EmptyStep<S,E>

All Implemented Interfaces:

TraversalHolder<S,E>, Step<S,E>, java.lang.Cloneable, java.util.Iterator<Traverser<E>>

public final class EmptyStep<S,E>
extends java.lang.Object
implements Step<S,E>, TraversalHolder<S,E>

Author:

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

Nested Class Summary

Nested classes/interfaces inherited from interface com.tinkerpop.gremlin.process.graph.marker.TraversalHolder

TraversalHolder.Child

Method Summary

Modifier and Type	Method and Description
void	addStart(Traverser<S> start) Add a single Traverser to the step.
void	addStarts(java.util.Iterator<Traverser<S>> starts) Add a iterator of Traverser objects of type S to the step.
EmptyStep<S,E>	clone() Cloning is used to duplicate steps for the purpose of traversal optimization and OLTP replication.
boolean	equals(java.lang.Object object)
java.lang.String	getId() Get the unique id of this step.
java.util.Optional<java.lang.String>	getLabel() Get the label of this step.
Step<E,?>	getNextStep() Get the next step to the current step.
Step<?,S>	getPreviousStep() Get the step prior to the current step.
<A,B> Traversal<A,B>	getTraversal() Get the Traversal that this step is contained within.
java.util.List<Traversal<S,E>>	getTraversals()
int	hashCode()
boolean	hasNext()
static <S,E> Step<S,E>	instance()
Traverser<E>	next()
void	reset() Reset the state of the step such that it has no incoming starts.
void	setId(java.lang.String id) Get the unique id of the step.
void	setLabel(java.lang.String label) Set the label of this step.
void	setNextStep(Step<E,?> step) Set the step that is next to the current step.
void	setPreviousStep(Step<?,S> step) Set the step that is previous to the current step.
void	setTraversal(Traversal<?,?> traversal) Set the Traversal that this step is contained within.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.tinkerpop.gremlin.process.Step

getRequirements

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

Methods inherited from interface com.tinkerpop.gremlin.process.graph.marker.TraversalHolder

asStep, executeTraversalOperations, getChildStrategies, getTraversalRequirements, resetTraversals

Method Detail

instance

public static <S,E> Step<S,E> instance()

addStarts

public void addStarts(java.util.Iterator<Traverser<S>> starts)

Description copied from interface: Step

Add a iterator of Traverser objects of type S to the step.

Specified by:

addStarts in interface Step<S,E>

Parameters:

starts - The iterator of objects to add

addStart

public void addStart(Traverser<S> start)

Description copied from interface: Step

Add a single Traverser to the step.

Specified by:

addStart in interface Step<S,E>

Parameters:

start - The traverser to add

setPreviousStep

public void setPreviousStep(Step<?,S> step)

Description copied from interface: Step

Set the step that is previous to the current step. Used for linking steps together to form a function chain.

Specified by:

setPreviousStep in interface Step<S,E>

Parameters:

step - the previous step of this step

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,E>

getPreviousStep

public Step<?,S> getPreviousStep()

Description copied from interface: Step

Get the step prior to the current step.

Specified by:

getPreviousStep in interface Step<S,E>

Returns:

The previous step

setNextStep

public void setNextStep(Step<E,?> step)

Description copied from interface: Step

Set the step that is next to the current step. Used for linking steps together to form a function chain.

Specified by:

setNextStep in interface Step<S,E>

Parameters:

step - the next step of this step

getNextStep

public Step<E,?> getNextStep()

Description copied from interface: Step

Get the next step to the current step.

Specified by:

getNextStep in interface Step<S,E>

Returns:

The next step

getTraversal

public <A,B> Traversal<A,B> getTraversal()

Description copied from interface: Step

Get the Traversal that this step is contained within.

Specified by:

getTraversal in interface Step<S,E>

Type Parameters:

A - The incoming object type of the traversal

B - The outgoing object type of the traversal

Returns:

The traversal of this step

setTraversal

public void setTraversal(Traversal<?,?> traversal)

Description copied from interface: Step

Set the Traversal that this step is contained within.

Specified by:

setTraversal in interface Step<S,E>

Parameters:

traversal - the new traversal for this step

clone

public EmptyStep<S,E> clone()
                     throws java.lang.CloneNotSupportedException

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,E>

Overrides:

clone in class java.lang.Object

Returns:

The cloned step

Throws:

java.lang.CloneNotSupportedException

getLabel

public java.util.Optional<java.lang.String> getLabel()

Description copied from interface: Step

Get the label of this step. If the step is not labeled, then an Optional.empty() is returned.

Specified by:

getLabel in interface Step<S,E>

Returns:

the optional label of the step

setLabel

public void setLabel(java.lang.String label)

Description copied from interface: Step

Set the label of this step.

Specified by:

setLabel in interface Step<S,E>

Parameters:

label - the label for this step

setId

public void setId(java.lang.String id)

Description copied from interface: Step

Get the unique id of the step. These ids can change when strategies are applied and anonymous traversals are embedded in the parent traversal. A developer should typically not need to call this method.

Specified by:

setId in interface Step<S,E>

Parameters:

id - the unique id of the step

getId

public java.lang.String getId()

Description copied from interface: Step

Get the unique id of this step.

Specified by:

getId in interface Step<S,E>

Returns:

the unique id of the step

hasNext

public boolean hasNext()

Specified by:

hasNext in interface java.util.Iterator<Traverser<E>>

next

public Traverser<E> next()

Specified by:

next in interface java.util.Iterator<Traverser<E>>

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object object)

Overrides:

equals in class java.lang.Object

getTraversals

public java.util.List<Traversal<S,E>> getTraversals()

Specified by:

getTraversals in interface TraversalHolder<S,E>