Package org.jgrapht.traverse
Class DepthFirstIterator<V,E>
- java.lang.Object
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- org.jgrapht.traverse.AbstractGraphIterator<V,E>
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- org.jgrapht.traverse.CrossComponentIterator<V,E,CrossComponentIterator.VisitColor>
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- org.jgrapht.traverse.DepthFirstIterator<V,E>
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- Type Parameters:
V
- the graph vertex typeE
- the graph edge type
- All Implemented Interfaces:
java.util.Iterator<V>
,GraphIterator<V,E>
- Direct Known Subclasses:
CycleDetector.ProbeIterator
public class DepthFirstIterator<V,E> extends CrossComponentIterator<V,E,CrossComponentIterator.VisitColor>
A depth-first iterator for a directed and an undirected graph. For this iterator to work correctly the graph must not be modified during iteration. Currently there are no means to ensure that, nor to fail-fast. The results of such modifications are undefined.- Since:
- Jul 29, 2003
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Nested Class Summary
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Nested classes/interfaces inherited from class org.jgrapht.traverse.CrossComponentIterator
CrossComponentIterator.SimpleContainer<T>, CrossComponentIterator.VisitColor
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Nested classes/interfaces inherited from class org.jgrapht.traverse.AbstractGraphIterator
AbstractGraphIterator.DirectedSpecifics<VV,EE>, AbstractGraphIterator.FlyweightEdgeEvent<VV,localE>, AbstractGraphIterator.FlyweightVertexEvent<VV>, AbstractGraphIterator.Specifics<VV,EE>, AbstractGraphIterator.UndirectedSpecifics<VV,EE>
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Field Summary
Fields Modifier and Type Field Description static java.lang.Object
SENTINEL
Sentinel object.private java.util.Deque<java.lang.Object>
stack
private TypeUtil<V>
vertexTypeDecl
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Fields inherited from class org.jgrapht.traverse.AbstractGraphIterator
nListeners, reusableEdgeEvent, reusableVertexEvent, specifics
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Constructor Summary
Constructors Constructor Description DepthFirstIterator(Graph<V,E> g)
Creates a new depth-first iterator for the specified graph.DepthFirstIterator(Graph<V,E> g, V startVertex)
Creates a new depth-first iterator for the specified graph.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected void
encounterVertex(V vertex, E edge)
Update data structures the first time we see a vertex.protected void
encounterVertexAgain(V vertex, E edge)
Called whenever we re-encounter a vertex.java.util.Deque<java.lang.Object>
getStack()
Retrieves the LIFO stack of vertices which have been encountered but not yet visited (WHITE).protected boolean
isConnectedComponentExhausted()
Returns true if there are no more uniterated vertices in the currently iterated connected component; false otherwise.protected V
provideNextVertex()
Returns the vertex to be returned in the following call to the iteratornext
method.private void
recordFinish()
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Methods inherited from class org.jgrapht.traverse.CrossComponentIterator
finishVertex, getGraph, getSeenData, hasNext, isSeenVertex, next, putSeenData
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Methods inherited from class org.jgrapht.traverse.AbstractGraphIterator
addTraversalListener, createGraphSpecifics, fireConnectedComponentFinished, fireConnectedComponentStarted, fireEdgeTraversed, fireVertexFinished, fireVertexTraversed, isCrossComponentTraversal, isReuseEvents, remove, removeTraversalListener, setCrossComponentTraversal, setReuseEvents
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Field Detail
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SENTINEL
public static final java.lang.Object SENTINEL
Sentinel object. Unfortunately, we can't use null, because ArrayDeque won't accept those. And we don't want to rely on the caller to provide a sentinel object for us. So we have to play typecasting games.
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stack
private java.util.Deque<java.lang.Object> stack
- See Also:
getStack()
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Constructor Detail
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DepthFirstIterator
public DepthFirstIterator(Graph<V,E> g)
Creates a new depth-first iterator for the specified graph.- Parameters:
g
- the graph to be iterated.
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DepthFirstIterator
public DepthFirstIterator(Graph<V,E> g, V startVertex)
Creates a new depth-first iterator for the specified graph. Iteration will start at the specified start vertex and will be limited to the connected component that includes that vertex. If the specified start vertex isnull
, iteration will start at an arbitrary vertex and will not be limited, that is, will be able to traverse all the graph.- Parameters:
g
- the graph to be iterated.startVertex
- the vertex iteration to be started.
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Method Detail
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isConnectedComponentExhausted
protected boolean isConnectedComponentExhausted()
Description copied from class:CrossComponentIterator
Returns true if there are no more uniterated vertices in the currently iterated connected component; false otherwise.- Specified by:
isConnectedComponentExhausted
in classCrossComponentIterator<V,E,CrossComponentIterator.VisitColor>
- Returns:
- true if there are no more uniterated vertices in the currently iterated connected component; false otherwise.
- See Also:
CrossComponentIterator.isConnectedComponentExhausted()
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encounterVertex
protected void encounterVertex(V vertex, E edge)
Description copied from class:CrossComponentIterator
Update data structures the first time we see a vertex.- Specified by:
encounterVertex
in classCrossComponentIterator<V,E,CrossComponentIterator.VisitColor>
- Parameters:
vertex
- the vertex encounterededge
- the edge via which the vertex was encountered, or null if the vertex is a starting point- See Also:
CrossComponentIterator.encounterVertex(Object, Object)
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encounterVertexAgain
protected void encounterVertexAgain(V vertex, E edge)
Description copied from class:CrossComponentIterator
Called whenever we re-encounter a vertex. The default implementation does nothing.- Specified by:
encounterVertexAgain
in classCrossComponentIterator<V,E,CrossComponentIterator.VisitColor>
- Parameters:
vertex
- the vertex re-encounterededge
- the edge via which the vertex was re-encountered- See Also:
CrossComponentIterator.encounterVertexAgain(Object, Object)
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provideNextVertex
protected V provideNextVertex()
Description copied from class:CrossComponentIterator
Returns the vertex to be returned in the following call to the iteratornext
method.- Specified by:
provideNextVertex
in classCrossComponentIterator<V,E,CrossComponentIterator.VisitColor>
- Returns:
- the next vertex to be returned by this iterator.
- See Also:
CrossComponentIterator.provideNextVertex()
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recordFinish
private void recordFinish()
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getStack
public java.util.Deque<java.lang.Object> getStack()
Retrieves the LIFO stack of vertices which have been encountered but not yet visited (WHITE). This stack also contains sentinel entries representing vertices which have been visited but are still GRAY. A sentinel entry is a sequence (v, SENTINEL), whereas a non-sentinel entry is just (v).- Returns:
- stack
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