org.jgrapht.traverse

Class DepthFirstIterator<V,E>

java.lang.Object

org.jgrapht.traverse.AbstractGraphIterator<V,E>

org.jgrapht.traverse.CrossComponentIterator<V,E,org.jgrapht.traverse.CrossComponentIterator.VisitColor>

org.jgrapht.traverse.DepthFirstIterator<V,E>

Type Parameters:

V - the graph vertex type

E - the graph edge type

All Implemented Interfaces:

java.util.Iterator<V>, GraphIterator<V,E>

public class DepthFirstIterator<V,E>
extends CrossComponentIterator<V,E,org.jgrapht.traverse.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

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.Object	SENTINEL Sentinel object.

Constructor Summary

Constructors

Constructor and 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.

Method Summary

Modifier and Type	Method and Description
java.util.Deque<java.lang.Object>	getStack() Retrieves the LIFO stack of vertices which have been encountered but not yet visited (WHITE).

Methods inherited from class org.jgrapht.traverse.CrossComponentIterator

getGraph, hasNext, next

Methods inherited from class org.jgrapht.traverse.AbstractGraphIterator

addTraversalListener, isCrossComponentTraversal, isReuseEvents, remove, removeTraversalListener, setCrossComponentTraversal, setReuseEvents

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Iterator

forEachRemaining

Field Detail

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.

Constructor Detail

DepthFirstIterator

public DepthFirstIterator(Graph<V,E> g)

Creates a new depth-first iterator for the specified graph.

Parameters:

g - the graph to be iterated.

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 is null, 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.

Method Detail

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