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

Class MergeEdgeStep<S>

java.lang.Object

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

org.apache.tinkerpop.gremlin.process.traversal.step.map.FlatMapStep<S,Edge>

org.apache.tinkerpop.gremlin.process.traversal.step.map.MergeEdgeStep<S>

All Implemented Interfaces:

Serializable, AutoCloseable, Cloneable, Iterator<Traverser.Admin<Edge>>, Step<S,Edge>, Configuring, Mutating<Event>, Parameterizing, TraversalOptionParent<Merge,S,Edge>, TraversalParent

Direct Known Subclasses:

TinkerMergeEdgeStep

public class MergeEdgeStep<S>
extends FlatMapStep<S,Edge>
implements Mutating<Event>, TraversalOptionParent<Merge,S,Edge>

Implementation for the mergeE() step covering both the start step version and the one used mid-traversal.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected CallbackRegistry<Event>	callbackRegistry
static Vertex	PLACEHOLDER_VERTEX

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
MergeEdgeStep(Traversal.Admin traversal, boolean isStart)
MergeEdgeStep(Traversal.Admin traversal, boolean isStart, Map<Object,Object> searchCreate)
MergeEdgeStep(Traversal.Admin traversal, boolean isStart, Traversal.Admin<?,Map<Object,Object>> searchCreateTraversal)

Method Summary

Modifier and Type	Method and Description
void	addChildOption(Merge token, Traversal.Admin<S,Edge> traversalOption) The child as defined by the token it takes, like Pick or Merge.
MergeEdgeStep<S>	clone() Cloning is used to duplicate steps for the purpose of traversal optimization and OLTP replication.
void	configure(Object... keyValues) Accept a configuration to the Step.
protected Stream<Edge>	createSearchStream(Map<Object,Object> search) Use the Map of search criteria to most efficiently return a Stream<Edge> of matching elements.
protected Iterator<Edge>	flatMap(Traverser.Admin<S> traverser)
CallbackRegistry<Event>	getCallbackRegistry()
<S,E> List<Traversal.Admin<S,E>>	getLocalChildren()
CallbackRegistry<Event>	getMutatingCallbackRegistry() Gets the callback registry for events that the step raises.
Traversal.Admin<S,Map<Object,Object>>	getOnCreateTraversal() Gets the traversal that will be used to provide the Map that will be the override to the one provided by the getSearchCreateTraversal() for edge creation events.
Traversal.Admin<S,Map<String,Object>>	getOnMatchTraversal() Gets the traversal that will be used to provide the Map that will be used to modify edges that match the search criteria of getSearchCreateTraversal().
Parameters	getParameters() Gets the parameters on the step.
Set<TraverserRequirement>	getRequirements() Provide the necessary TraverserRequirement that must be met by the traverser in order for the step to function properly.
Traversal.Admin<S,Map<Object,Object>>	getSearchCreateTraversal() Gets the traversal that will be used to provide the Map that will be used to search for edges.
int	hashCode()
boolean	isFirst() Determine if this is the first pass through processNextStart().
boolean	isStart() Determines if this is a start step.
protected Traverser.Admin<Edge>	processNextStart()
void	reset() Reset the state of the step such that it has no incoming starts.
protected Vertex	resolveVertex(Traverser.Admin<S> traverser, Map<Object,Object> searchCreate, Direction direction) Little helper method that will resolve Direction map keys to a Vertex which is the currency of this step.
void	setTraversal(Traversal.Admin<?,?> parentTraversal) Set the Traversal that this step is contained within.
String	toString()
protected Vertex	tryAttachVertex(Vertex maybeAttachable) Tries to attach a Vertex to its host Graph of the traversal.
static void	validateMapInput(Map<?,Object> m, boolean ignoreTokens) Validates input to any Map arguments to this step.

Methods inherited from class org.apache.tinkerpop.gremlin.process.traversal.step.map.FlatMapStep

closeIterator

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

addLabel, addStart, addStarts, equals, getId, getLabels, getNextStep, getPreviousStep, getStarts, getTraversal, hasNext, hasStarts, isTraverserStepIdAndLabelsSetByChild, next, prepareTraversalForNextStep, 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.TraversalParent

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

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

equals

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

Field Detail

PLACEHOLDER_VERTEX

public static final Vertex PLACEHOLDER_VERTEX

callbackRegistry

protected CallbackRegistry<Event> callbackRegistry

Constructor Detail

MergeEdgeStep

public MergeEdgeStep(Traversal.Admin traversal,
                     boolean isStart)

MergeEdgeStep

public MergeEdgeStep(Traversal.Admin traversal,
                     boolean isStart,
                     Map<Object,Object> searchCreate)

MergeEdgeStep

public MergeEdgeStep(Traversal.Admin traversal,
                     boolean isStart,
                     Traversal.Admin<?,Map<Object,Object>> searchCreateTraversal)

Method Detail

getSearchCreateTraversal

public Traversal.Admin<S,Map<Object,Object>> getSearchCreateTraversal()

Gets the traversal that will be used to provide the Map that will be used to search for edges. This Map also will be used as the default data set to be used to create a edge if the search is not successful.

getOnCreateTraversal

public Traversal.Admin<S,Map<Object,Object>> getOnCreateTraversal()

Gets the traversal that will be used to provide the Map that will be the override to the one provided by the getSearchCreateTraversal() for edge creation events.

getOnMatchTraversal

public Traversal.Admin<S,Map<String,Object>> getOnMatchTraversal()

Gets the traversal that will be used to provide the Map that will be used to modify edges that match the search criteria of getSearchCreateTraversal().

isStart

public boolean isStart()

Determines if this is a start step.

isFirst

public boolean isFirst()

Determine if this is the first pass through processNextStart().

getCallbackRegistry

public CallbackRegistry<Event> getCallbackRegistry()

addChildOption

public void addChildOption(Merge token,
                           Traversal.Admin<S,Edge> traversalOption)

Description copied from interface: TraversalOptionParent

The child as defined by the token it takes, like Pick or Merge. This traversal may be of local or global scope depending on the step implementation that works with option().

Specified by:

addChildOption in interface TraversalOptionParent<Merge,S,Edge>

getLocalChildren

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

Specified by:

getLocalChildren in interface TraversalParent

configure

public void configure(Object... keyValues)

Description copied from interface: Configuring

Accept a configuration to the Step. Note that this interface extends Parameterizing and so there is an expectation that the Step implementation will have a Parameters instance that will house any values passed to this method. Storing these configurations in Parameters is not a requirement however, IF the configuration is an expected option for the step and can be stored on a member field that can be accessed on the step by more direct means (i.e. like a getter method).

Specified by:

configure in interface Configuring

getParameters

public Parameters getParameters()

Description copied from interface: Parameterizing

Gets the parameters on the step.

Specified by:

getParameters in interface Parameterizing

processNextStart

protected Traverser.Admin<Edge> processNextStart()

Overrides:

processNextStart in class FlatMapStep<S,Edge>

createSearchStream

protected Stream<Edge> createSearchStream(Map<Object,Object> search)

Use the Map of search criteria to most efficiently return a Stream<Edge> of matching elements. Providers might override this method when extending this step to provide their own optimized mechanisms for matching the list of edges. This implementation is only optimized for the T.id so any other usage will simply be in-memory filtering which could be slow.

flatMap

protected Iterator<Edge> flatMap(Traverser.Admin<S> traverser)

Specified by:

flatMap in class FlatMapStep<S,Edge>

resolveVertex

protected Vertex resolveVertex(Traverser.Admin<S> traverser,
                               Map<Object,Object> searchCreate,
                               Direction direction)

Little helper method that will resolve Direction map keys to a Vertex which is the currency of this step. Since this step can accept a Vertex as the traverser it uses that as a default value in the case where Direction is not specified in the Map. As a result the Map value overrides the traverser. Note that if this is a start step then the traverser will contain a PLACEHOLDER_VERTEX which is basically just a dummy to use as a marker where it will be assumed a Map argument to the step will have the necessary Vertex to allow the step to do its work. If the Direction contains something other than a Vertex it will become the T.id to a fresh ReferenceVertex.

tryAttachVertex

protected Vertex tryAttachVertex(Vertex maybeAttachable)

Tries to attach a Vertex to its host Graph of the traversal. If the Vertex cannot be found then an IllegalArgumentException is expected.

validateMapInput

public static void validateMapInput(Map<?,Object> m,
                                    boolean ignoreTokens)

Validates input to any Map arguments to this step. For Merge.onMatch updates cannot be applied to immutable parts of an Edge (id, label, incident vertices) so those can be ignored in the validation.

getMutatingCallbackRegistry

public CallbackRegistry<Event> getMutatingCallbackRegistry()

Description copied from interface: Mutating

Gets the callback registry for events that the step raises.

Specified by:

getMutatingCallbackRegistry in interface Mutating<Event>

hashCode

public int hashCode()

Overrides:

hashCode in class AbstractStep<S,Edge>

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,Edge>

Overrides:

reset in class FlatMapStep<S,Edge>

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,Edge>

Returns:

the set of requirements

toString

public String toString()

Overrides:

toString in class AbstractStep<S,Edge>

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,Edge>

Overrides:

setTraversal in class AbstractStep<S,Edge>

Parameters:

parentTraversal - the new traversal for this step

clone

public MergeEdgeStep<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 Step.reset() is called. Moreover, the previous and next steps should be set to EmptyStep.

Specified by:

clone in interface Step<S,Edge>

Overrides:

clone in class AbstractStep<S,Edge>

Returns:

The cloned step