org.apache.tinkerpop.gremlin.process.traversal

Interface TraversalStrategy<S extends TraversalStrategy>

All Superinterfaces:

Comparable<Class<? extends TraversalStrategy>>, Serializable

All Known Subinterfaces:

TraversalStrategy.DecorationStrategy, TraversalStrategy.FinalizationStrategy, TraversalStrategy.OptimizationStrategy, TraversalStrategy.ProviderOptimizationStrategy, TraversalStrategy.VerificationStrategy

public interface TraversalStrategy<S extends TraversalStrategy>
extends Serializable, Comparable<Class<? extends TraversalStrategy>>

A TraversalStrategy defines a particular atomic operation for mutating a Traversal prior to its evaluation. There are 5 pre-defined "traversal categories": TraversalStrategy.DecorationStrategy, TraversalStrategy.OptimizationStrategy, TraversalStrategy.ProviderOptimizationStrategy, TraversalStrategy.FinalizationStrategy, and TraversalStrategy.VerificationStrategy. Strategies within a category are sorted amongst themselves and then category sorts are applied in the ordered specified previous. That is, decorations are applied, then optimizations, then provider optimizations, then finalizations, and finally, verifications. If a strategy does not fit within the specified categories, then it can simply implement TraversalStrategy and can have priors/posts that span categories.

A traversal strategy should be a final class as various internal operations on a strategy are based on its ability to be assigned to more general classes. A traversal strategy should typically be stateless with a public static instance() method. However, at limit, a traversal strategy can have a state defining constructor (typically via a "builder"), but that state can not mutate once instantiated.

Author:

Marko A. Rodriguez (http://markorodriguez.com), Matthias Broecheler (me@matthiasb.com)

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	TraversalStrategy.DecorationStrategy Implemented by strategies that adds "application logic" to the traversal (e.g.
static interface	TraversalStrategy.FinalizationStrategy Implemented by strategies that do final behaviors that require a fully compiled traversal to work (e.g.
static interface	TraversalStrategy.OptimizationStrategy Implemented by strategies that rewrite the traversal to be more efficient, but with the same semantics (e.g.
static interface	TraversalStrategy.ProviderOptimizationStrategy Implemented by strategies that rewrite the traversal to be more efficient, but with the same semantics.
static interface	TraversalStrategy.VerificationStrategy Implemented by strategies where there is no more behavioral tweaking of the traversal required.

Field Summary

Fields

Modifier and Type	Field and Description
static String	STRATEGY

Method Summary

Modifier and Type	Method and Description
void	apply(Traversal.Admin<?,?> traversal)
default Set<Class<? extends S>>	applyPost() The set of strategies that must be executed after this strategy is executed.
default Set<Class<? extends S>>	applyPrior() The set of strategies that must be executed before this strategy is executed.
default int	compareTo(Class<? extends TraversalStrategy> otherTraversalCategory)
default org.apache.commons.configuration.Configuration	getConfiguration() Get the configuration representation of this strategy.
default Class<S>	getTraversalCategory() The type of traversal strategy -- i.e.

Field Detail

STRATEGY

static final String STRATEGY

See Also:

Constant Field Values

Method Detail

apply

void apply(Traversal.Admin<?,?> traversal)

applyPrior

default Set<Class<? extends S>> applyPrior()

The set of strategies that must be executed before this strategy is executed. If there are no ordering requirements, the default implementation returns an empty set.

Returns:

the set of strategies that must be executed prior to this one.

applyPost

default Set<Class<? extends S>> applyPost()

The set of strategies that must be executed after this strategy is executed. If there are no ordering requirements, the default implementation returns an empty set.

Returns:

the set of strategies that must be executed post this one

getTraversalCategory

default Class<S> getTraversalCategory()

The type of traversal strategy -- i.e. TraversalStrategy.DecorationStrategy, TraversalStrategy.OptimizationStrategy, TraversalStrategy.FinalizationStrategy, or TraversalStrategy.VerificationStrategy.

Returns:

the traversal strategy category class

getConfiguration

default org.apache.commons.configuration.Configuration getConfiguration()

Get the configuration representation of this strategy. This is useful for converting a strategy into a serialized form.

Returns:

the configuration used to create this strategy

compareTo

default int compareTo(Class<? extends TraversalStrategy> otherTraversalCategory)

Specified by:

compareTo in interface Comparable<Class<? extends TraversalStrategy>>