org.apache.xml.dtm.ref
Class DTMAxisIteratorBase

java.lang.Object
  org.apache.xml.dtm.ref.DTMAxisIteratorBase

All Implemented Interfaces:

Cloneable, DTMAxisIterator

Direct Known Subclasses:

DTMDefaultBaseIterators.InternalAxisIteratorBase

public abstract class DTMAxisIteratorBase

extends Object

implements DTMAxisIterator

This class serves as a default base for implementations of DTMAxisIterators.

Field Summary

protected boolean	_includeSelf True if the start node should be considered part of the iteration.
protected boolean	_isRestartable True if this iteration can be restarted.
private int	_last The position of the last node within the iteration, as defined by XPath.
protected int	_markedNode The position of the marked node within the iteration; a saved itaration state that we may want to come back to.
private int	_position The position of the current node within the iteration, as defined by XPath.
protected int	_startNode The handle to the start, or root, of the iteration.

Fields inherited from interface org.apache.xml.dtm.DTMAxisIterator

END

Constructor Summary

DTMAxisIteratorBase()

Method Summary

DTMAxisIterator	cloneIterator() Returns a deep copy of this iterator.
int	getAxis() Returns the axis being iterated, if it is known.
int	getLast() Returns the position of the last node within the iteration, as defined by XPath.
int	getPosition()
int	getStartNode() Get start to END should 'close' the iterator, i.e. subsequent call to next() should return END.
DTMAxisIterator	includeSelf() Set the flag to include the start node in the iteration.
boolean	isDocOrdered() Returns true if all the nodes in the iteration well be returned in document order.
boolean	isReverse()
DTMAxisIterator	reset() Resets the iterator to the last start node.
protected DTMAxisIterator	resetPosition() Reset the position to zero.
protected int	returnNode(int node) Do any final cleanup that is required before returning the node that was passed in, and then return it.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.xml.dtm.DTMAxisIterator

gotoMark, next, setMark, setStartNode

Field Detail

_last

private int _last

The position of the last node within the iteration, as defined by XPath. Note that this is _not_ the node's handle within the DTM. Also, don't confuse it with the current (most recently returned) position.

_position

private int _position

The position of the current node within the iteration, as defined by XPath. Note that this is _not_ the node's handle within the DTM!

_markedNode

protected int _markedNode

The position of the marked node within the iteration; a saved itaration state that we may want to come back to. Note that only one mark is maintained; there is no stack.

_startNode

protected int _startNode

The handle to the start, or root, of the iteration. Set this to END to construct an empty iterator.

_includeSelf

protected boolean _includeSelf

True if the start node should be considered part of the iteration. False will cause it to be skipped.

_isRestartable

protected boolean _isRestartable

True if this iteration can be restarted. False otherwise (eg, if we are iterating over a stream that can not be re-scanned, or if the iterator was produced by cloning another iterator.)

Constructor Detail

DTMAxisIteratorBase

public DTMAxisIteratorBase()

Method Detail

getStartNode

public int getStartNode()

Get start to END should 'close' the iterator, i.e. subsequent call to next() should return END.

Specified by:

getStartNode in interface DTMAxisIterator

Returns:

The root node of the iteration.

reset

public DTMAxisIterator reset()

Description copied from interface: DTMAxisIterator

Resets the iterator to the last start node.

Specified by:

reset in interface DTMAxisIterator

Returns:

A DTMAxisIterator which has been reset to the start node, which may or may not be the same as this iterator.

includeSelf

public DTMAxisIterator includeSelf()

Set the flag to include the start node in the iteration.

Returns:

This default method returns just returns this DTMAxisIterator, after setting the flag. (Returning "this" permits C++-style chaining of method calls into a single expression.)

getLast

public int getLast()

Returns the position of the last node within the iteration, as defined by XPath. In a forward iterator, I believe this equals the number of nodes which this iterator will yield. In a reverse iterator, I believe it should return 1 (since the "last" is the first produced.) This may be an expensive operation when called the first time, since it may have to iterate through a large part of the document to produce its answer.

Specified by:

getLast in interface DTMAxisIterator

Returns:

The number of nodes in this iterator (forward) or 1 (reverse).

getPosition

public int getPosition()

Specified by:

getPosition in interface DTMAxisIterator

Returns:

The position of the current node within the set, as defined by XPath. Note that this is one-based, not zero-based.

isReverse

public boolean isReverse()

Specified by:

isReverse in interface DTMAxisIterator

Returns:

true if this iterator has a reversed axis, else false

cloneIterator

public DTMAxisIterator cloneIterator()

Returns a deep copy of this iterator. Cloned iterators may not be restartable. The iterator being cloned may or may not become non-restartable as a side effect of this operation.

Specified by:

cloneIterator in interface DTMAxisIterator

Returns:

a deep copy of this iterator.

returnNode

protected final int returnNode(int node)

Do any final cleanup that is required before returning the node that was passed in, and then return it. The intended use is
return returnNode(node); %REVIEW% If we're calling it purely for side effects, should we really be bothering with a return value? Something like
accept(node); return node;
would probably optimize just about as well and avoid questions about whether what's returned could ever be different from what's passed in.

Parameters:

node - Node handle which iteration is about to yield.

Returns:

The node handle passed in.

resetPosition

protected final DTMAxisIterator resetPosition()

Reset the position to zero. NOTE that this does not change the iteration state, only the position number associated with that state. %REVIEW% Document when this would be used?

Returns:

This instance.

isDocOrdered

public boolean isDocOrdered()

Returns true if all the nodes in the iteration well be returned in document order.

Returns:

true as a default.

getAxis

public int getAxis()

Returns the axis being iterated, if it is known.

Returns:

Axis.CHILD, etc., or -1 if the axis is not known or is of multiple types.