org.htmlparser.util
Class NodeTreeWalker

java.lang.Object
  org.htmlparser.util.NodeTreeWalker

All Implemented Interfaces:

NodeIterator

public class NodeTreeWalker
extends Object
implements NodeIterator

A class for walking a tree of Node objects, in either a depth-first or breadth-first manner. The following two diagrams show the represent tree traversal with the two different methods.

Depth-first traversal	Breadth-first traversal

Author:

ian_macfarlane

Field Summary

protected Node	mCurrentNode The current Node element, which will be a child of the root Node, or null.
protected boolean	mDepthFirst Whether the tree traversal method used is depth-first (default) or breadth-first.
protected int	mMaxDepth The maximum depth (child-parent links) from which this NodeTreeWalker may be removed from the root Node.
protected Node	mNextNode The next Node element after the current Node element.
protected Node	mRootNode The root Node element which defines the scope of the current tree to walk.

Constructor Summary

NodeTreeWalker(Node rootNode)
Creates a new instance of NodeTreeWalker using depth-first tree traversal, without limits on how deep it may traverse.

NodeTreeWalker(Node rootNode, boolean depthFirst)
Creates a new instance of NodeTreeWalker using the specified type of tree traversal, without limits on how deep it may traverse.

NodeTreeWalker(Node rootNode, boolean depthFirst, int maxDepth)
Creates a new instance of NodeTreeWalker using the specified type of tree traversal and maximum depth from the root Node to traverse.

Method Summary

Node	getCurrentNode() Get the Node in the tree that the NodeTreeWalker is current at.
int	getCurrentNodeDepth() Get the number of places down that the current Node is from the root Node.
int	getMaxDepth() The maximum depth (number of child-parent links) below the root Node that this NodeTreeWalker may traverse.
protected Node	getNextNodeBreadthFirst() Traverses to the next Node from the current Node using breadth-first tree traversal
protected Node	getNextNodeDepthFirst() Traverses to the next Node from the current Node using depth-first tree traversal
Node	getRootNode() Get the root Node that defines the scope of the tree to traverse.
boolean	hasMoreNodes() Returns whether or not there are more nodes available based on the current configuration of this NodeTreeWalker.
protected void	initRootNode(Node rootNode) Sets the root Node to be the given Node.
boolean	isDepthFirst() Whether the NodeTreeWalker is currently set to use depth-first or breadth-first tree traversal.
Node	nextNode() Traverses to the next Node from the current Node, using either depth-first or breadth-first tree traversal as appropriate.
void	removeMaxDepthRestriction() Removes any restrictions in place that prevent this NodeTreeWalker from traversing beyond a certain depth.
void	reset() Resets the current position in the tree, such that calling nextNode() will return the first Node again.
void	setCurrentNodeAsRootNode() Sets the current Node as the root Node.
void	setDepthFirst(boolean depthFirst) Sets whether the NodeTreeWalker should use depth-first or breadth-first tree traversal.
void	setRootNode(Node rootNode) Sets the specified Node as the root Node.

Methods inherited from class java.lang.Object

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

Field Detail

mRootNode

protected Node mRootNode

The root Node element which defines the scope of the current tree to walk.

mCurrentNode

protected Node mCurrentNode

The current Node element, which will be a child of the root Node, or null.

mNextNode

protected Node mNextNode

The next Node element after the current Node element. Stored for internal use only.

mMaxDepth

protected int mMaxDepth

The maximum depth (child-parent links) from which this NodeTreeWalker may be removed from the root Node. A value of -1 indicates that there is no depth restriction.

mDepthFirst

protected boolean mDepthFirst

Whether the tree traversal method used is depth-first (default) or breadth-first.

Constructor Detail

NodeTreeWalker

public NodeTreeWalker(Node rootNode)

Creates a new instance of NodeTreeWalker using depth-first tree traversal, without limits on how deep it may traverse.

Parameters:

rootNode - Node The Node to set as the root of the tree.

Throws:

NullPointerException - if root Node is null.

NodeTreeWalker

public NodeTreeWalker(Node rootNode,
                      boolean depthFirst)

Creates a new instance of NodeTreeWalker using the specified type of tree traversal, without limits on how deep it may traverse.

Parameters:

rootNode - The Node to set as the root of the tree.

depthFirst - Whether to use depth-first (true) or breadth-first (false) tree traversal.

Throws:

NullPointerException - if rootNode is null.

NodeTreeWalker

public NodeTreeWalker(Node rootNode,
                      boolean depthFirst,
                      int maxDepth)

Creates a new instance of NodeTreeWalker using the specified type of tree traversal and maximum depth from the root Node to traverse.

Parameters:

rootNode - The Node to set as the root of the tree.

depthFirst - Whether to use depth-first (true) or breadth-first (false) tree traversal.

maxDepth - The maximum depth from the root Node that this NodeTreeWalker may traverse. This must be > 0 or equal to -1.

Throws:

NullPointerException - if rootNode is null.

IllegalArgumentException - maxDepth is not > 0 or equal to -1.

Method Detail

isDepthFirst

public boolean isDepthFirst()

Whether the NodeTreeWalker is currently set to use depth-first or breadth-first tree traversal.

Returns:

True if depth-first tree-traversal is used, or false if breadth-first tree-traversal is being used.

setDepthFirst

public void setDepthFirst(boolean depthFirst)

Sets whether the NodeTreeWalker should use depth-first or breadth-first tree traversal.

Parameters:

depthFirst - Whether to use depth-first (true) or breadth-first (false) tree traversal.

getMaxDepth

public int getMaxDepth()

The maximum depth (number of child-parent links) below the root Node that this NodeTreeWalker may traverse.

Returns:

The maximum depth that this NodeTreeWalker can traverse to.

removeMaxDepthRestriction

public void removeMaxDepthRestriction()

Removes any restrictions in place that prevent this NodeTreeWalker from traversing beyond a certain depth.

getRootNode

public Node getRootNode()

Get the root Node that defines the scope of the tree to traverse.

Returns:

The root Node.

getCurrentNode

public Node getCurrentNode()

Get the Node in the tree that the NodeTreeWalker is current at.

Returns:

The current Node.

setCurrentNodeAsRootNode

public void setCurrentNodeAsRootNode()
                              throws NullPointerException

Sets the current Node as the root Node. Resets the current position in the tree.

Throws:

NullPointerException - if the current Node is null (i.e. if the tree traversal has not yet begun).

setRootNode

public void setRootNode(Node rootNode)
                 throws NullPointerException

Sets the specified Node as the root Node. Resets the current position in the tree.

Parameters:

rootNode - The Node to set as the root of the tree.

Throws:

NullPointerException - if rootNode is null.

reset

public void reset()

Resets the current position in the tree, such that calling nextNode() will return the first Node again.

nextNode

public Node nextNode()

Traverses to the next Node from the current Node, using either depth-first or breadth-first tree traversal as appropriate.

Specified by:

nextNode in interface NodeIterator

Returns:

The next Node from the current Node.

getCurrentNodeDepth

public int getCurrentNodeDepth()

Get the number of places down that the current Node is from the root Node. Returns 1 if current Node is a child of the root Node. Returns 0 if this NodeTreeWalker has not yet traversed to any Nodes.

Returns:

The depth the current Node is from the root Node.

hasMoreNodes

public boolean hasMoreNodes()

Returns whether or not there are more nodes available based on the current configuration of this NodeTreeWalker.

Specified by:

hasMoreNodes in interface NodeIterator

Returns:

True if there are more Nodes available, based on the current configuration, or false otherwise.

initRootNode

protected void initRootNode(Node rootNode)
                     throws NullPointerException

Sets the root Node to be the given Node. Resets the current position in the tree.

Parameters:

rootNode - The Node to set as the root of the tree.

Throws:

NullPointerException - if rootNode is null.

getNextNodeDepthFirst

protected Node getNextNodeDepthFirst()

Traverses to the next Node from the current Node using depth-first tree traversal

Returns:

The next Node from the current Node using depth-first tree traversal.

getNextNodeBreadthFirst

protected Node getNextNodeBreadthFirst()

Traverses to the next Node from the current Node using breadth-first tree traversal

Returns:

The next Node from the current Node using breadth-first tree traversal.