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public interface StopEvaluator
A client hook for evaluating whether the traverser should traverse beyond
a specific node. When a traverser is created, the client parameterizes it
with a StopEvaluator. The traverser then invokes the
isStopNode()
operation just before traversing
the relationships of a node, allowing the client to either approve or
disapprove of traversing beyond that node.
When implementing a StopEvaluator, the client investigates the
information encapsulated in a TraversalPosition
to decide whether
to block traversal beyond a node. For example, here's a snippet detailing
a StopEvaluator that blocks traversal beyond a node if it has a certain
property value:
StopEvaluator stopEvaluator = new StopEvaluator()
{
// Block traversal if the node has a property with key 'key' and value
// 'someValue'
public boolean isStopNode( TraversalPosition position )
{
Node node = position.previousNode();
Object someProp = node.getProperty( "key" );
return someProp instanceof String &&
((String) someProp).equals( "someValue" );
}
};
Field Summary | |
---|---|
static StopEvaluator |
DEPTH_ONE
Traverses to depth 1. |
static StopEvaluator |
END_OF_GRAPH
Traverse until the end of the graph. |
static StopEvaluator |
END_OF_NETWORK
Deprecated. |
Method Summary | |
---|---|
boolean |
isStopNode(TraversalPosition currentPos)
Method invoked by traverser to see if current position is a stop node. |
Field Detail |
---|
static final StopEvaluator END_OF_NETWORK
END_OF_GRAPH
. Traverse until the end of
network, this evaluator returns false
all the time.
static final StopEvaluator END_OF_GRAPH
false
all the time.
static final StopEvaluator DEPTH_ONE
Method Detail |
---|
boolean isStopNode(TraversalPosition currentPos)
currentPos
- The traversal position
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