org.cdlib.xtf.lazyTree
Class TreeEnumeration

Object
  TreeEnumeration

All Implemented Interfaces:

AxisIterator, LookaheadIterator, SequenceIterator, UnfailingIterator

Direct Known Subclasses:

AncestorEnumeration, ChildEnumeration, DescendantEnumeration, FollowingEnumeration, FollowingSiblingEnumeration, PrecedingEnumeration, PrecedingOrAncestorEnumeration, PrecedingSiblingEnumeration

abstract class TreeEnumeration
extends Object
implements AxisIterator, LookaheadIterator

Field Summary

protected NodeImpl	current
protected NodeImpl	next
protected NodeTest	nodeTest
protected int	position
protected NodeImpl	start

Fields inherited from interface SequenceIterator

GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD

Constructor Summary

TreeEnumeration(NodeImpl origin, NodeTest nodeTest)
Create an axis enumeration for a given type and name of node, from a given origin node

Method Summary

protected void	advance() Advance along the axis until a node is found that matches the required criteria
Value	atomize() Return the atomized value of the current node.
protected boolean	conforms(NodeImpl node) Test whether a node conforms to the node type and name constraints.
Item	current() Return the current Item
int	getProperties() Get properties of this iterator, as a bit-significant integer.
CharSequence	getStringValue() Return the string value of the current node.
boolean	hasNext() Determine whether there are more items to come.
AxisIterator	iterateAxis(byte axis, NodeTest test) Return an iterator over an axis, starting at the current node.
boolean	moveNext() Move to the next node, without returning it.
Item	next() Return the next node in the enumeration
int	position() Return the current position
protected abstract void	step() Advance one step along the axis: the resulting node might not meet the required criteria for inclusion

Methods inherited from class Object

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

Methods inherited from interface UnfailingIterator

getAnother

Field Detail

start

protected NodeImpl start

next

protected NodeImpl next

nodeTest

protected NodeTest nodeTest

current

protected NodeImpl current

position

protected int position

Constructor Detail

TreeEnumeration

public TreeEnumeration(NodeImpl origin,
                       NodeTest nodeTest)

Create an axis enumeration for a given type and name of node, from a given origin node

Parameters:

origin - the node from which the axis originates

nodeTest - test to be satisfied by the returned nodes, or null if all nodes are to be returned.

Method Detail

conforms

protected boolean conforms(NodeImpl node)

Test whether a node conforms to the node type and name constraints. Note that this returns true if the supplied node is null, this is a way of terminating a loop.

advance

protected final void advance()

Advance along the axis until a node is found that matches the required criteria

step

protected abstract void step()

Advance one step along the axis: the resulting node might not meet the required criteria for inclusion

hasNext

public boolean hasNext()

Determine whether there are more items to come. Note that this operation is stateless and it is not necessary (or usual) to call it before calling next(). It is used only when there is an explicit need to tell if we are at the last element.

Specified by:

hasNext in interface LookaheadIterator

Returns:

true if there are more items in the sequence

moveNext

public boolean moveNext()

Move to the next node, without returning it. Returns true if there is a next node, false if the end of the sequence has been reached. After calling this method, the current node may be retrieved using the current() function.

Specified by:

moveNext in interface AxisIterator

next

public final Item next()

Return the next node in the enumeration

Specified by:

next in interface SequenceIterator

Specified by:

next in interface UnfailingIterator

current

public final Item current()

Return the current Item

Specified by:

current in interface SequenceIterator

Specified by:

current in interface UnfailingIterator

position

public final int position()

Return the current position

Specified by:

position in interface SequenceIterator

Specified by:

position in interface UnfailingIterator

iterateAxis

public AxisIterator iterateAxis(byte axis,
                                NodeTest test)

Return an iterator over an axis, starting at the current node.

Specified by:

iterateAxis in interface AxisIterator

Parameters:

axis - the axis to iterate over, using a constant such as Axis.CHILD

test - a predicate to apply to the nodes before returning them.

Throws:

NullPointerException - if there is no current node

atomize

public Value atomize()
              throws XPathException

Return the atomized value of the current node.

Specified by:

atomize in interface AxisIterator

Returns:

the atomized value.

Throws:

NullPointerException - if there is no current node

XPathException

getStringValue

public CharSequence getStringValue()

Return the string value of the current node.

Specified by:

getStringValue in interface AxisIterator

Returns:

the string value, as an instance of CharSequence.

Throws:

NullPointerException - if there is no current node

getProperties

public int getProperties()

Get properties of this iterator, as a bit-significant integer.

Specified by:

getProperties in interface SequenceIterator

Returns:

the properties of this iterator. This will be some combination of properties such as GROUNDED, LAST_POSITION_FINDER, and LOOKAHEAD. It is always acceptable to return the value zero, indicating that there are no known special properties. It is acceptable for the properties of the iterator to change depending on its state.