NodeFilter

All Known Implementing Classes:

Collector.FirstFinder
```
public interface NodeFilter
```
Node filter interface. Provide an implementing class to NodeTraversor to iterate through nodes.
This interface provides two methods, head and tail. The head method is called when the node is first seen, and the tail method when all of the node's children have been visited. As an example, head can be used to create a start tag for a node, and tail to create the end tag.

For every node, the filter has to decide whether to
- continue (NodeFilter.FilterResult.CONTINUE),
- skip all children (NodeFilter.FilterResult.SKIP_CHILDREN),
- skip node entirely (NodeFilter.FilterResult.SKIP_ENTIRELY),
- remove the subtree (NodeFilter.FilterResult.REMOVE),
- interrupt the iteration and return (NodeFilter.FilterResult.STOP).
The difference between NodeFilter.FilterResult.SKIP_CHILDREN and NodeFilter.FilterResult.SKIP_ENTIRELY is that the first will invoke tail(Node, int) on the node, while the latter will not. Within tail(Node, int), both are equivalent to NodeFilter.FilterResult.CONTINUE.

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static class NodeFilter.FilterResult
Filter decision.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`NodeFilter.FilterResult`	`head(Node node, int depth)`	Callback for when a node is first visited.
`NodeFilter.FilterResult`	`tail(Node node, int depth)`	Callback for when a node is last visited, after all of its descendants have been visited.

- Method Detail
  - head
```
NodeFilter.FilterResult head(Node node,
                             int depth)
```
    Callback for when a node is first visited.
    
    Parameters:
    
    node - the node being visited.
    
    depth - the depth of the node, relative to the root node. E.g., the root node has depth 0, and a child node of that will have depth 1.
    
    Returns:
    
    Filter decision
  - tail
```
NodeFilter.FilterResult tail(Node node,
                             int depth)
```
    Callback for when a node is last visited, after all of its descendants have been visited.
    
    Parameters:
    
    node - the node being visited.
    
    depth - the depth of the node, relative to the root node. E.g., the root node has depth 0, and a child node of that will have depth 1.
    
    Returns:
    
    Filter decision