org.neo4j.graphdb
Interface TraversalPosition

public interface TraversalPosition

Encapsulates information about the current traversal position. The TraversalPosition is mainly used in StopEvaluator.isStopNode(TraversalPosition) and ReturnableEvaluator.isReturnableNode(TraversalPosition) for evaluating whether a position in a traversal is a point where the traversal should stop or if the node at that position is to be part of the result respectively.

Method Summary

Node	currentNode() Returns the current node.
int	depth() Returns the current traversal depth.
boolean	isStartNode() Returns true if the current position is the start node, false otherwise.
Relationship	lastRelationshipTraversed() Return the last relationship traversed.
boolean	notStartNode() Returns true if the current position is anywhere except on the start node, false if it is on the start node.
Node	previousNode() Returns the previous node.
int	returnedNodesCount() Returns the number of nodes returned by the traverser so far.

Method Detail

currentNode

Node currentNode()

Returns the current node.

Returns:

The current node

previousNode

Node previousNode()

Returns the previous node. If this TraversalPosition represents the start node null is returned.

Returns:

The previous node, or null

lastRelationshipTraversed

Relationship lastRelationshipTraversed()

Return the last relationship traversed. If this TraversalPosition represents the start node null is returned.

Returns:

The last relationship traversed, or null.

depth

int depth()

Returns the current traversal depth. The traversal depth is the length of the path taken to reach the current traversal position. This is not necessarily the length of shortest path from the start node to the node at the current position. When traversing breadth first the depth is the length of the shortest path from the start node to the node at the current position, but when traversing depth first there might exist shorter paths from the start node to the node at this position.

Returns:

The current traversal depth

returnedNodesCount

int returnedNodesCount()

Returns the number of nodes returned by the traverser so far.

Returns:

The number of returned nodes.

notStartNode

boolean notStartNode()

Returns true if the current position is anywhere except on the start node, false if it is on the start node. This is useful because code in the evaluators usually have to treat the edge case of the start node separately and using this method makes that code a lot cleaner. This allows for much cleaner code where null checks can be avoided for return values from lastRelationshipTraversed() and previousNode(), such as in this example:

 
 public boolean isStopNode( TraversalPosition currentPos )
 {
     // Stop at nodes reached through a SOME_RELATIONSHIP.
     return currentPos.notStartNode()
         && currentPos.lastRelationshipTraversed().isType(
             MyRelationshipTypes.SOME_RELATIONSHIP );
 }
 
 

Returns:

true if the this TraversalPosition is not at the start node, false if it is.

isStartNode

boolean isStartNode()

Returns true if the current position is the start node, false otherwise. This is useful because code in the evaluators usually have to treat the edge case of the start node separately and using this method makes that code a lot cleaner. This allows for much cleaner code where null checks can be avoided for return values from lastRelationshipTraversed() and previousNode(), such as in this example:

 
 public boolean isReturnableNode( TraversalPosition currentPos )
 {
     // The start node, and nodes reached through SOME_RELATIONSHIP
     // are returnable.
     return currentPos.isStartNode()
         || currentPos.lastRelationshipTraversed().isType(
             MyRelationshipTypes.SOME_RELATIONSHIP );
 }
 
 

Returns:

true if the this TraversalPosition is at the start node, false if it is not.