org.jaxen.util

Class PrecedingAxisIterator

java.lang.Object

org.jaxen.util.PrecedingAxisIterator

All Implemented Interfaces:

Iterator

public class PrecedingAxisIterator
extends Object
implements Iterator

Represents the XPath preceding axis. The "preceding axis contains all nodes in the same document as the context node that are before the context node in document order, excluding any ancestors and excluding attribute nodes and namespace nodes."

This implementation of 'preceding' works like so: the preceding axis includes preceding siblings of this node and their descendants. Also, for each ancestor node of this node, it includes all preceding siblings of that ancestor, and their descendants. Finally, it includes the ancestor nodes themselves.

The reversed descendant-or-self axes that are required are calculated using a stack of reversed 'child-or-self' axes. When asked for a node, it is always taken from a child-or-self axis. If it was the last node on that axis, the node is returned. Otherwise, this axis is pushed on the stack, and the process is repeated with the child-or-self of the node. Eventually this recurses down to the last descendant of any node, then works back up to the root.

Most object models could provide a faster implementation of the reversed 'children-or-self' used here.

Version:

1.2b12

Constructor Summary

Constructors

Constructor and Description
PrecedingAxisIterator(Object contextNode, Navigator navigator) Create a new preceding axis iterator.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	hasNext() Returns true if there are any preceding nodes remaining; false otherwise.
Object	next() Returns the next preceding node.
void	remove() This operation is not supported.

Methods inherited from class java.lang.Object

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

Constructor Detail

PrecedingAxisIterator

public PrecedingAxisIterator(Object contextNode,
                     Navigator navigator)
                      throws UnsupportedAxisException

Create a new preceding axis iterator.

Parameters:

contextNode - the node to start from

navigator - the object model specific navigator

Throws:

UnsupportedAxisException

Method Detail

hasNext

public boolean hasNext()

Returns true if there are any preceding nodes remaining; false otherwise.

Specified by:

hasNext in interface Iterator

Returns:

true if any preceding nodes remain; false otherwise

See Also:

Iterator.hasNext()

next

public Object next()
            throws NoSuchElementException

Returns the next preceding node.

Specified by:

next in interface Iterator

Returns:

the next preceding node

Throws:

NoSuchElementException - if no preceding nodes remain

See Also:

Iterator.next()

remove

public void remove()
            throws UnsupportedOperationException

This operation is not supported.

Specified by:

remove in interface Iterator

Throws:

UnsupportedOperationException - always