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

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


Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.