org.jaxen.util
Class PrecedingAxisIterator

java.lang.Object
  extended byorg.jaxen.util.PrecedingAxisIterator
All Implemented Interfaces:
java.util.Iterator

public class PrecedingAxisIterator
extends java.lang.Object
implements java.util.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

Field Summary
private  java.util.Iterator ancestorOrSelf
           
private  java.util.ListIterator childrenOrSelf
           
private  Navigator navigator
           
private  java.util.Iterator precedingSibling
           
private  java.util.ArrayList stack
           
 
Constructor Summary
PrecedingAxisIterator(java.lang.Object contextNode, Navigator navigator)
          Create a new preceding axis iterator.
 
Method Summary
private  java.util.ListIterator childrenOrSelf(java.lang.Object node)
           
 boolean hasNext()
          Returns true if there are any preceding nodes remaining; false otherwise.
 java.lang.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
 

Field Detail

ancestorOrSelf

private java.util.Iterator ancestorOrSelf

precedingSibling

private java.util.Iterator precedingSibling

childrenOrSelf

private java.util.ListIterator childrenOrSelf

stack

private java.util.ArrayList stack

navigator

private Navigator navigator
Constructor Detail

PrecedingAxisIterator

public PrecedingAxisIterator(java.lang.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
Method Detail

hasNext

public boolean hasNext()
Returns true if there are any preceding nodes remaining; false otherwise.

Specified by:
hasNext in interface java.util.Iterator
Returns:
true if any preceding nodes remain; false otherwise
See Also:
Iterator.hasNext()

childrenOrSelf

private java.util.ListIterator childrenOrSelf(java.lang.Object node)

next

public java.lang.Object next()
                      throws java.util.NoSuchElementException
Returns the next preceding node.

Specified by:
next in interface java.util.Iterator
Returns:
the next preceding node
Throws:
java.util.NoSuchElementException - if no preceding nodes remain
See Also:
Iterator.next()

remove

public void remove()
            throws java.lang.UnsupportedOperationException
This operation is not supported.

Specified by:
remove in interface java.util.Iterator
Throws:
java.lang.UnsupportedOperationException - always