 Type Parameters:
V
 the graph vertex type.E
 the graph edge type.
 All Implemented Interfaces:
Iterator<V>
,GraphIterator<V,
E>
Every vertex has an implicit label (they aren't used explicitly in order to reduce time and memory complexity). When some vertex is returned by this iterator, its index is the number of vertices in this graph minus number of already returned vertices. For a given vertex v its label is a concatenation of indices of already returned vertices, that were also its neighbours, with some separator between them. For example, 7#4#3 is a valid vertex label.
Iterator chooses vertex with lexicographically largest label and returns it. It breaks ties arbitrarily. For more information on lexicographical BFS see the following article: Corneil D.G. (2004) Lexicographic Breadth First Search – A Survey. In: Hromkovič J., Nagl M., Westfechtel B. (eds) GraphTheoretic Concepts in Computer Science. WG 2004. Lecture Notes in Computer Science, vol 3353. Springer, Berlin, Heidelberg; and the following paper:CS 762: Graphtheoretic algorithms. Lecture notes of a graduate course. University of Waterloo.
For this iterator to work correctly the graph must not be modified during iteration. Currently there are no means to ensure that, nor to failfast. The results of such modifications are undefined.
Note: only vertex events are fired by this iterator.
 Author:
 Timofey Chudakov

Field Summary
Fields inherited from class org.jgrapht.traverse.AbstractGraphIterator
crossComponentTraversal, graph, nListeners, reusableEdgeEvent, reusableVertexEvent, reuseEvents

Constructor Summary
ConstructorDescriptionLexBreadthFirstIterator
(Graph<V, E> graph) Creates new lexicographical breadthfirst iterator forgraph
. 
Method Summary
Modifier and TypeMethodDescriptionboolean
hasNext()
Checks whether there exist unvisited vertices.boolean
Test whether this iterator is set to traverse the graph across connected components.next()
Returns the next vertex in the ordering.void
setCrossComponentTraversal
(boolean crossComponentTraversal) Sets the cross component traversal flag  indicates whether to traverse the graph across connected components.Methods inherited from class org.jgrapht.traverse.AbstractGraphIterator
addTraversalListener, createEdgeTraversalEvent, createVertexTraversalEvent, fireConnectedComponentFinished, fireConnectedComponentStarted, fireEdgeTraversed, fireVertexFinished, fireVertexTraversed, getGraph, isReuseEvents, remove, removeTraversalListener, setReuseEvents
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface java.util.Iterator
forEachRemaining

Constructor Details

LexBreadthFirstIterator
Creates new lexicographical breadthfirst iterator forgraph
. Parameters:
graph
 the graph to be iterated.


Method Details

hasNext
public boolean hasNext()Checks whether there exist unvisited vertices. Returns:
 true if there exist unvisited vertices.

next
Returns the next vertex in the ordering. Returns:
 the next vertex in the ordering.

isCrossComponentTraversal
public boolean isCrossComponentTraversal()Test whether this iterator is set to traverse the graph across connected components.Always returns true since this iterator doesn't care about connected components.
 Specified by:
isCrossComponentTraversal
in interfaceGraphIterator<V,
E>  Overrides:
isCrossComponentTraversal
in classAbstractGraphIterator<V,
E>  Returns:
true
if traverses across connected components, otherwisefalse
.

setCrossComponentTraversal
public void setCrossComponentTraversal(boolean crossComponentTraversal) Sets the cross component traversal flag  indicates whether to traverse the graph across connected components.Trying to disable the cross components nature of this iterator will result into throwing a
IllegalArgumentException
. Overrides:
setCrossComponentTraversal
in classAbstractGraphIterator<V,
E>  Parameters:
crossComponentTraversal
 iftrue
traverses across connected components.
