Traversal (Apache TinkerPop 3.0.2-incubating API)

All Superinterfaces:

Cloneable, Iterator<E>, Serializable

All Known Subinterfaces:

GraphTraversal<S,E>, GraphTraversal.Admin<S,E>, Traversal.Admin<S,E>

All Known Implementing Classes:

AbstractLambdaTraversal, ConstantTraversal, DefaultGraphTraversal, DefaultTraversal, ElementValueTraversal, EmptyGraphTraversal, EmptyTraversal, IdentityTraversal, LoopTraversal, TokenTraversal, TrueTraversal
```
public interface Traversal<S,E>
extends Iterator<E>, Serializable, Cloneable
```
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: StandardTraversalEngine (OLTP) and ComputerTraversalEngine (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)

Nested Class Summary

Nested Classes
Modifier and Type	Interface and Description
`static interface`	`Traversal.Admin<S,E>`
`static class`	`Traversal.Exceptions` A collection of `Exception` types associated with Traversal execution.

Method Summary

All Methods Instance Methods Default Methods
Modifier and Type	Method and Description
`default Traversal.Admin<S,E>`	`asAdmin()` Get access to administrative methods of the traversal via its accompanying `Traversal.Admin`.
`default <C extends Collection<E>> C`	`fill(C collection)` Add all the results of the traversal to the provided collection.
`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.
`default void`	`forEachRemaining(Consumer<? super E> action)`
`default <A,B> Traversal<A,B>`	`iterate()` Iterate all the `Traverser` instances in the traversal.
`default List<E>`	`next(int amount)` Get the next n-number of results from the traversal.
`default BulkSet<E>`	`toBulkSet()` Put all the results into a `BulkSet`.
`default List<E>`	`toList()` Put all the results into an `ArrayList`.
`default Set<E>`	`toSet()` Put all the results into a `HashSet`.
`default Stream<E>`	`toStream()` Return the traversal as a `Stream`.
`default Optional<E>`	`tryNext()` Return an `Optional` of the next E object in the traversal.

Methods inherited from interface java.util.Iterator
hasNext, next, remove

- Method Detail
  - 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 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.
  - 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
  - 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<E>

Interface Traversal<S,E>

Nested Class Summary

Method Summary

Methods inherited from interface java.util.Iterator

Method Detail

asAdmin

tryNext

next

toList

toSet

toBulkSet

toStream

fill

iterate

forEachRemaining

forEachRemaining