net.sf.saxon.tree.util
Class Navigator.DescendantEnumeration

java.lang.Object
  net.sf.saxon.tree.iter.AxisIteratorImpl
      net.sf.saxon.tree.util.Navigator.BaseEnumeration
          net.sf.saxon.tree.util.Navigator.DescendantEnumeration

All Implemented Interfaces:

SequenceIterator, AxisIterator, UnfailingIterator

Enclosing class:

Navigator

public static final class Navigator.DescendantEnumeration
extends Navigator.BaseEnumeration

General-purpose implementation of the descendant and descendant-or-self axes, in terms of the child axis. But it also has the option to return the descendants in reverse document order; this is used when evaluating the preceding axis. Note that the includeSelf option should not be used when scanning in reverse order, as the self node will always be returned first.

Field Summary

Fields inherited from class net.sf.saxon.tree.iter.AxisIteratorImpl

current, position

Fields inherited from interface net.sf.saxon.om.SequenceIterator

GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD

Constructor Summary

Navigator.DescendantEnumeration(NodeInfo start, boolean includeSelf, boolean forwards)
Create an iterator over the descendant or descendant-or-self axis

Method Summary

void	advance() The advance() method must be provided in each concrete implementation.
SequenceIterator	getAnother() Get another SequenceIterator that iterates over the same items as the original, but which is repositioned at the start of the sequence.

Methods inherited from class net.sf.saxon.tree.util.Navigator.BaseEnumeration

next

Methods inherited from class net.sf.saxon.tree.iter.AxisIteratorImpl

atomize, close, current, getProperties, getStringValue, iterateAxis, moveNext, position

Methods inherited from class java.lang.Object

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

Constructor Detail

Navigator.DescendantEnumeration

public Navigator.DescendantEnumeration(NodeInfo start,
                                       boolean includeSelf,
                                       boolean forwards)

Create an iterator over the descendant or descendant-or-self axis

Parameters:

start - the initial context node

includeSelf - true if the "self" node is to be included

forwards - true for a forwards iteration, false for reverse order

Method Detail

advance

public void advance()

Description copied from class: Navigator.BaseEnumeration

The advance() method must be provided in each concrete implementation. It must leave the variable current set to the next node to be returned in the iteration, or to null if there are no more nodes to be returned.

Specified by:

advance in class Navigator.BaseEnumeration

getAnother

public SequenceIterator getAnother()

Description copied from interface: SequenceIterator

Get another SequenceIterator that iterates over the same items as the original, but which is repositioned at the start of the sequence.

This method allows access to all the items in the sequence without disturbing the current position of the iterator. Internally, its main use is in evaluating the last() function.

This method does not change the state of the iterator.

Specified by:

getAnother in interface SequenceIterator

Specified by:

getAnother in interface UnfailingIterator

Specified by:

getAnother in class Navigator.BaseEnumeration

Returns:

a SequenceIterator that iterates over the same items, positioned before the first item