com.phoenixst.plexus.traversals
Class Walker

java.lang.Object
  com.phoenixst.plexus.traversals.Walker

All Implemented Interfaces:

Traverser, Iterator

public class Walker
extends Object
implements Traverser

A Traverser which walks a graph, with no cycle detection. Each iteration step moves from one node to an adjacent node. The first node returned is the start node, and no Edge is traversed to reach it.

Since:

1.0

Version:

$Revision: 1.9 $

Author:

Ray A. Conner

Constructor Summary

Walker(Object startNode, Graph graph, org.apache.commons.collections.Predicate traverserPredicate)
Creates a new Walker.

Walker(Object startNode, Graph graph, org.apache.commons.collections.Transformer incidentEdgeGetter)
Creates a new Walker.

Walker(Object startNode, OrientedForest forest)
Creates a new unmodifiable Walker, which traverses the ancestors of the specified startNode.

Walker(Object startNode, org.apache.commons.collections.Transformer incidentEdgeGetter)
Creates a new unmodifiable Walker.

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()
Object	next()
void	remove() Removes from the underlying Graph the last node returned by next(), effectively terminating this iteration.
void	removeEdge() Removes from the underlying Graph the Edge that would be returned by getEdge() (optional operation).

Methods inherited from class java.lang.Object

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

Constructor Detail

Walker

public Walker(Object startNode,
              Graph graph,
              org.apache.commons.collections.Predicate traverserPredicate)

Creates a new Walker.

Walker

public Walker(Object startNode,
              OrientedForest forest)

Creates a new unmodifiable Walker, which traverses the ancestors of the specified startNode.

Walker

public Walker(Object startNode,
              org.apache.commons.collections.Transformer incidentEdgeGetter)

Creates a new unmodifiable Walker.

Walker

public Walker(Object startNode,
              Graph graph,
              org.apache.commons.collections.Transformer incidentEdgeGetter)

Creates a new Walker. If the graph argument is null, the Walker will be unmodifiable.

Method Detail

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator

next

public Object next()

Specified by:

next in interface Iterator

remove

public void remove()

Removes from the underlying Graph the last node returned by next(), effectively terminating this iteration.

Description copied from interface: Iterator

Specified by:

remove in interface Iterator

getEdge

public Graph.Edge getEdge()

Description copied from interface: Traverser

Returns the 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().

Specified by:

getEdge in interface Traverser

Returns:

The Edge which was traversed to get to the last node returned by next(), or null if no Edge was traversed.

removeEdge

public void removeEdge()

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().

Specified by:

removeEdge in interface Traverser