org.apache.nutch.util

Class NodeWalker

java.lang.Object

org.apache.nutch.util.NodeWalker

public class NodeWalker
extends Object

A utility class that allows the walking of any DOM tree using a stack instead of recursion. As the node tree is walked the next node is popped off of the stack and all of its children are automatically added to the stack to be called in tree order.

Currently this class is not thread safe. It is assumed that only one thread will be accessing the NodeWalker at any given time.

Constructor Summary

Constructors

Constructor and Description
NodeWalker(Node rootNode) Starts the Node tree from the root node.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	hasNext()
Node	nextNode() Returns the next Node on the stack and pushes all of its children onto the stack, allowing us to walk the node tree without the use of recursion.
void	skipChildren() Skips over and removes from the node stack the children of the last node.

Methods inherited from class java.lang.Object

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

Constructor Detail

NodeWalker

public NodeWalker(Node rootNode)

Starts the Node tree from the root node.

Parameters:

rootNode -

Method Detail

nextNode

public Node nextNode()

Returns the next Node on the stack and pushes all of its children onto the stack, allowing us to walk the node tree without the use of recursion. If there are no more nodes on the stack then null is returned.

Returns:

Node The next Node on the stack or null if there isn't a next node.

skipChildren

public void skipChildren()

Skips over and removes from the node stack the children of the last node. When getting a next node from the walker, that node's children are automatically added to the stack. You can call this method to remove those children from the stack.

This is useful when you don't want to process deeper into the current path of the node tree but you want to continue processing sibling nodes.

hasNext

public boolean hasNext()

Returns:

returns true if there are more nodes on the current stack.