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java.lang.Object com.phoenixst.plexus.traversals.DepthFirstTraverser
public class DepthFirstTraverser
A depth-first Traverser
for a Graph
,
with no cycle detection. This Traverser
hits each
node twice (assuming it has not been removed), once on the way
down and once on the way back up. The first and last nodes
returned are the start node, and no Edge
is traversed
to reach it. All of the caveats concerning the ordering of the
operations hasNext()
, next()
, and
remove()
detailed by the Traverser
class
documentation apply here.
Constructor Summary | |
---|---|
DepthFirstTraverser(Object startNode,
Graph graph,
org.apache.commons.collections.Predicate traverserPredicate)
Creates a new DepthFirstTraverser . |
|
DepthFirstTraverser(Object startNode,
Graph graph,
org.apache.commons.collections.Transformer traverserFactory)
Creates a new DepthFirstTraverser . |
|
DepthFirstTraverser(Object startNode,
OrientedForest forest)
Creates a new DepthFirstTraverser , which
depth-first traverses the descendants of the specified
startNode . |
|
DepthFirstTraverser(Object startNode,
org.apache.commons.collections.Transformer traverserFactory)
Creates a new DepthFirstTraverser . |
Method Summary | |
---|---|
Graph.Edge |
getEdge()
Returns the Edge which was traversed to get to
the last node returned by next() , or
null if no Edge was traversed. |
boolean |
hasNext()
|
boolean |
isDescending()
Returns true if the last node returned by next() is being traversed away from the start node,
false if the traversal is on its way back out. |
Object |
next()
|
void |
prune()
Signals this Traverser to not explore beyond the
last node returned by next() . |
void |
remove()
Removes from the underlying Graph the last node
returned by next() . |
void |
removeEdge()
Removes from the underlying Graph the
Edge that would be returned by getEdge() . |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public DepthFirstTraverser(Object startNode, Graph graph, org.apache.commons.collections.Predicate traverserPredicate)
DepthFirstTraverser
.
public DepthFirstTraverser(Object startNode, OrientedForest forest)
DepthFirstTraverser
, which
depth-first traverses the descendants of the specified
startNode
. The specified startNode
cannot be removed by remove()
when using this
constructor.
public DepthFirstTraverser(Object startNode, org.apache.commons.collections.Transformer traverserFactory)
DepthFirstTraverser
. The specified
startNode
cannot be removed by remove()
when using this constructor.
public DepthFirstTraverser(Object startNode, Graph graph, org.apache.commons.collections.Transformer traverserFactory)
DepthFirstTraverser
. If the
graph
argument is null
, the
specified startNode
cannot be removed by remove()
.
Method Detail |
---|
public boolean hasNext()
hasNext
in interface Iterator
public Object next()
next
in interface Iterator
public void remove()
Graph
the last node
returned by next()
. If this method is called during
descent, this will prevent the exploration of those nodes that
would have been reached through the removed node (unless they
are reachable by another route). This method can be called
only once per call to next()
. The behavior of
this Traverser
is unspecified if the underlying
graph structure is modified while the traversal is in progress
in any way other than by calling this method or removeEdge()
.
remove
in interface Iterator
IllegalStateException
- if next()
has not
yet been called, or remove()
or
removeEdge
has been called after the last call to
next()
.public Graph.Edge getEdge()
Traverser
Edge
which was traversed to get to
the last node returned by next()
, or
null
if no Edge
was traversed. This
call can be made only if remove()
or removeEdge()
has not been called after the last
call to next()
.
getEdge
in interface Traverser
Edge
which was traversed to get to
the last node returned by next()
, or
null
if no Edge
was traversed.public void removeEdge()
Graph
the
Edge
that would be returned by getEdge()
. If this method is called during descent, this
will prevent the exploration of those nodes that would have
been reached through the removed Edge
(unless
they are reachable by another route).
Description copied from interface: Traverser
Removes from the underlying Graph
the
Edge
that would be returned by getEdge()
(optional operation). If no Edge
was
traversed (as in the root of a breadth-first search), this
method throws a IllegalStateException
. This
method can be called only once per call to next()
. The behavior of a traverser is unspecified if the
underlying graph structure is modified while the traversal is
in progress in any way other than by calling this method or
remove()
.
removeEdge
in interface Traverser
public void prune()
PruningTraverser
Traverser
to not explore beyond the
last node returned by next()
. This method can
be called only once per call to next()
. After
calling this method (and before calling next()
again), remove()
, getEdge()
,
and removeEdge()
will all throw
IllegalStateExceptions
.
prune
in interface PruningTraverser
public boolean isDescending()
true
if the last node returned by next()
is being traversed away from the start node,
false
if the traversal is on its way back out.
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