com.phoenixst.plexus.traversals
Class PostOrderTraverser

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

All Implemented Interfaces:

Traverser, Iterator

public class PostOrderTraverser
extends Object
implements Traverser

A post-order depth-first Traverser for a Graph, with no cycle detection. The last node returned is the start node, and no Edge is traversed to reach it. All of the caveats concerning the ordering of the operations hasNext(), next(), and remove() detailed by the Traverser class documentation apply here.

Since:

1.0

Version:

$Revision: 1.6 $

Author:

Ray A. Conner

Constructor Summary

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

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

PostOrderTraverser(Object startNode, OrientedForest forest)
Creates a new PostOrderTraverser, which depth-first traverses the descendants of the specified startNode.

PostOrderTraverser(Object startNode, org.apache.commons.collections.Transformer traverserFactory)
Creates a new PostOrderTraverser.

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()
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

PostOrderTraverser

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

Creates a new PostOrderTraverser.

PostOrderTraverser

public PostOrderTraverser(Object startNode,
                          OrientedForest forest)

Creates a new PostOrderTraverser, which depth-first traverses the descendants of the specified startNode. The specified startNode cannot be removed by remove() when using this constructor.

PostOrderTraverser

public PostOrderTraverser(Object startNode,
                          org.apache.commons.collections.Transformer traverserFactory)

Creates a new PostOrderTraverser. The specified startNode cannot be removed by remove() when using this constructor.

PostOrderTraverser

public PostOrderTraverser(Object startNode,
                          Graph graph,
                          org.apache.commons.collections.Transformer traverserFactory)

Creates a new PostOrderTraverser. If the graph argument is null, the specified startNode cannot be removed by remove().

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()

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