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:
2.0.0