org.jscience.computing.graph.iterators
Class CrossComponentIterator

java.lang.Object
  extended by org.jscience.computing.graph.iterators.AbstractGraphIterator
      extended by org.jscience.computing.graph.iterators.CrossComponentIterator
All Implemented Interfaces:
java.util.Iterator, GraphIterator
Direct Known Subclasses:
BreadthFirstIterator, ClosestFirstIterator, DepthFirstIterator, TopologicalOrderIterator

public abstract class CrossComponentIterator
extends AbstractGraphIterator

Provides a cross-connected-component traversal functionality for iterator subclasses.

Since:
Jan 31, 2004

Constructor Summary
CrossComponentIterator(Graph g, java.lang.Object startVertex)
          Creates a new iterator for the specified graph.
 
Method Summary
protected abstract  void encounterVertex(java.lang.Object vertex, Edge edge)
          Update data structures the first time we see a vertex.
protected abstract  void encounterVertexAgain(java.lang.Object vertex, Edge edge)
          Called whenever we re-encounter a vertex.
protected  java.lang.Object getSeenData(java.lang.Object vertex)
          Access the data stored for a seen vertex.
 boolean hasNext()
           
protected abstract  boolean isConnectedComponentExhausted()
          Returns true if there are no more uniterated vertices in the currently iterated connected component; false otherwise.
protected  boolean isSeenVertex(java.lang.Object vertex)
          Determines whether a vertex has been seen yet by this traversal.
 java.lang.Object next()
           
protected abstract  java.lang.Object provideNextVertex()
          Returns the vertex to be returned in the following call to the iterator next method.
protected  java.lang.Object putSeenData(java.lang.Object vertex, java.lang.Object data)
          Stores iterator-dependent data for a vertex that has been seen.
 
Methods inherited from class org.jscience.computing.graph.iterators.AbstractGraphIterator
addTraversalListener, fireConnectedComponentFinished, fireConnectedComponentStarted, fireEdgeTraversed, fireVertexTraversed, isCrossComponentTraversal, isReuseEvents, remove, removeTraversalListener, setCrossComponentTraversal, setReuseEvents
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

CrossComponentIterator

public CrossComponentIterator(Graph g,
                              java.lang.Object startVertex)
Creates a new iterator for the specified graph. Iteration will start at the specified start vertex. If the specified start vertex is null, Iteration will start at an arbitrary graph vertex.

Parameters:
g - the graph to be iterated.
startVertex - the vertex iteration to be started.
Throws:
java.lang.NullPointerException
java.lang.IllegalArgumentException
Method Detail

hasNext

public boolean hasNext()
See Also:
Iterator.hasNext()

next

public java.lang.Object next()
See Also:
Iterator.next()

isConnectedComponentExhausted

protected abstract boolean isConnectedComponentExhausted()
Returns true if there are no more uniterated vertices in the currently iterated connected component; false otherwise.

Returns:
true if there are no more uniterated vertices in the currently iterated connected component; false otherwise.

encounterVertex

protected abstract void encounterVertex(java.lang.Object vertex,
                                        Edge edge)
Update data structures the first time we see a vertex.

Parameters:
vertex - the vertex encountered
edge - the edge via which the vertex was encountered, or null if the vertex is a starting point

provideNextVertex

protected abstract java.lang.Object provideNextVertex()
Returns the vertex to be returned in the following call to the iterator next method.

Returns:
the next vertex to be returned by this iterator.

getSeenData

protected java.lang.Object getSeenData(java.lang.Object vertex)
Access the data stored for a seen vertex.

Parameters:
vertex - a vertex which has already been seen.
Returns:
data associated with the seen vertex or null if no data was associated with the vertex. A null return can also indicate that the vertex was explicitly associated with null.

isSeenVertex

protected boolean isSeenVertex(java.lang.Object vertex)
Determines whether a vertex has been seen yet by this traversal.

Parameters:
vertex - vertex in question
Returns:
true if vertex has already been seen

encounterVertexAgain

protected abstract void encounterVertexAgain(java.lang.Object vertex,
                                             Edge edge)
Called whenever we re-encounter a vertex. The default implementation does nothing.

Parameters:
vertex - the vertex re-encountered
edge - the edge via which the vertex was re-encountered

putSeenData

protected java.lang.Object putSeenData(java.lang.Object vertex,
                                       java.lang.Object data)
Stores iterator-dependent data for a vertex that has been seen.

Parameters:
vertex - a vertex which has been seen.
data - data to be associated with the seen vertex.
Returns:
previous value associated with specified vertex or null if no data was associated with the vertex. A null return can also indicate that the vertex was explicitly associated with null.