private static final class EndpointPairIterator.Undirected<N> extends EndpointPairIterator<N>
EndpointPair
s, we keep track of the nodes that we have visited. When processing endpoint
pairs, we skip if the "other node" is in the visited set, as shown below:
Nodes = {N1, N2, N3, N4} N2 __ / \ | | N1----N3 N4__| Visited Nodes = {} EndpointPair [N1, N2] - return EndpointPair [N1, N3] - return Visited Nodes = {N1} EndpointPair [N2, N1] - skip EndpointPair [N2, N3] - return Visited Nodes = {N1, N2} EndpointPair [N3, N1] - skip EndpointPair [N3, N2] - skip Visited Nodes = {N1, N2, N3} EndpointPair [N4, N4] - return Visited Nodes = {N1, N2, N3, N4}
Modifier and Type | Field and Description |
---|---|
private java.util.Set<N> |
visitedNodes |
node, successorIterator
Modifier | Constructor and Description |
---|---|
private |
Undirected(Graph<N> graph) |
Modifier and Type | Method and Description |
---|---|
protected EndpointPair<N> |
computeNext()
Returns the next element.
|
advance, of
endOfData, hasNext, next, peek
remove
private java.util.Set<N> visitedNodes
protected EndpointPair<N> computeNext()
AbstractIterator
AbstractIterator.endOfData()
when there are no elements left in the iteration. Failure to
do so could result in an infinite loop.
The initial invocation of AbstractIterator.hasNext()
or AbstractIterator.next()
calls
this method, as does the first invocation of hasNext
or next
following each successful call to next
. Once the
implementation either invokes endOfData
or throws an exception,
computeNext
is guaranteed to never be called again.
If this method throws an exception, it will propagate outward to the
hasNext
or next
invocation that invoked this method. Any
further attempts to use the iterator will result in an IllegalStateException
.
The implementation of this method may not invoke the hasNext
,
next
, or AbstractIterator.peek()
methods on this instance; if it does, an
IllegalStateException
will result.
computeNext
in class AbstractIterator<EndpointPair<N>>
endOfData
was called
during execution, the return value will be ignored.