Package org.apache.tinkerpop.gremlin.process.traversal

Interface Traversal<S,E>

All Superinterfaces:
AutoCloseable, Cloneable, Iterator<E>, Serializable
All Known Subinterfaces:
GraphTraversal<S,E>, GraphTraversal.Admin<S,E>, Traversal.Admin<S,E>
public interface Traversal<S,E> extends Iterator<E>, Serializable, Cloneable, AutoCloseable
A Traversal represents a directed walk over a Graph. This is the base interface for all traversal's, where each extending interface is seen as a domain specific language. For example, GraphTraversal is a domain specific language for traversing a graph using "graph concepts" (e.g. vertices, edges). Another example may represent the graph using "social concepts" (e.g. people, cities, artifacts). A Traversal is evaluated in one of two ways: iterator-based OLTP or GraphComputer-based OLAP. OLTP traversals leverage an iterator and are executed within a single JVM (with data access allowed to be remote). OLAP traversals leverage GraphComputer and are executed between multiple JVMs (and/or cores).
Author:
Marko A. Rodriguez (http://markorodriguez.com)

  • Method Details

    • asAdmin

      default Traversal.Admin<S,E> asAdmin()
      Get access to administrative methods of the traversal via its accompanying Traversal.Admin.
      Returns:
      the admin of this traversal

    • tryNext

      default Optional<E> tryNext()
      Return an Optional of the next E object in the traversal. If the traversal is empty, then an Optional.empty() is returned.
      Returns:
      an optional of the next object in the traversal

    • next

      default List<E> next(int amount)
      Get the next n-number of results from the traversal. If the traversal has less than n-results, then only that number of results are returned.
      Parameters:
      amount - the number of results to get
      Returns:
      the n-results in a List

    • toList

      default List<E> toList()
      Put all the results into an ArrayList.
      Returns:
      the results in a list

    • toSet

      default Set<E> toSet()
      Put all the results into a HashSet.
      Returns:
      the results in a set

    • toBulkSet

      default org.apache.tinkerpop.gremlin.process.traversal.step.util.BulkSet<E> toBulkSet()
      Put all the results into a BulkSet. This can reduce both time and space when aggregating results by ensuring a weighted set.
      Returns:
      the results in a bulk set

    • toStream

      default Stream<E> toStream()
      Return the traversal as a Stream.
      Returns:
      the traversal as a stream.

    • promise

      default <T> CompletableFuture<T> promise(Function<Traversal<S,E>,T> traversalFunction)
      Starts a promise to execute a function on the current Traversal that will be completed in the future. Note that this method can only be used if the Traversal is constructed using AnonymousTraversalSource.withRemote(Configuration). Calling this method otherwise will yield an IllegalStateException.

    • fill

      default <C extends Collection<E>> C fill(C collection)
      Add all the results of the traversal to the provided collection.
      Parameters:
      collection - the collection to fill
      Returns:
      the collection now filled

    • iterate

      default <A, B> Traversal<A,B> iterate()
      Iterate all the Traverser instances in the traversal. What is returned is the empty traversal. It is assumed that what is desired from the computation is are the sideEffects yielded by the traversal.
      Returns:
      the fully drained traversal

    • discard

      default Traversal<S,E> discard()
      Filter all traversers in the traversal. Formerly named none() prior to 3.8.0.
      Since:
      3.8.0
      See Also:

    • profile

      default Traversal<S,org.apache.tinkerpop.gremlin.process.traversal.util.TraversalMetrics> profile()
      Profile the traversal.
      Returns:
      the updated traversal with respective ProfileSideEffectStep.

    • explain

      default org.apache.tinkerpop.gremlin.process.traversal.util.TraversalExplanation explain()
      Return a TraversalExplanation that shows how this traversal will mutate with each applied TraversalStrategy.
      Returns:
      a traversal explanation

    • forEachRemaining

      default <E2> void forEachRemaining(Class<E2> endType, Consumer<E2> consumer)
      A traversal can be rewritten such that its defined end type E may yield objects of a different type. This helper method allows for the casting of the output to the known the type.
      Type Parameters:
      E2 - the known output type of the traversal
      Parameters:
      endType - the true output type of the traversal
      consumer - a Consumer to process each output

    • forEachRemaining

      default void forEachRemaining(Consumer<? super E> action)
      Specified by:
      forEachRemaining in interface Iterator<S>

    • close

      default void close() throws Exception
      Releases resources opened in any steps that implement AutoCloseable. If this method is overridden,the implementer should invoke notifyClose().
      Specified by:
      close in interface AutoCloseable
      Throws:
      Exception

    • notifyClose

      default void notifyClose()
      Gets a callback from close() for additional operations specific to the Traversal implementation. A good implementation will use close() to release resources in steps and this method to release resources specific to the Traversal implementations.