net.sf.saxon.tree.linked
Class TreeEnumeration

java.lang.Object
  extended by net.sf.saxon.tree.linked.TreeEnumeration
All Implemented Interfaces:
SequenceIterator, AxisIterator, LookaheadIterator, 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 net.sf.saxon.om.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.
 void close()
          Close the iterator.
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 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface net.sf.saxon.tree.iter.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
Returns:
the next Item. If there are no more nodes, return null.

current

public final Item current()
Return the current Item

Specified by:
current in interface SequenceIterator
Specified by:
current in interface UnfailingIterator
Returns:
the current item, that is, the item most recently returned by next()

position

public final int position()
Return the current position

Specified by:
position in interface SequenceIterator
Specified by:
position in interface UnfailingIterator
Returns:
the position of the current item (the item most recently returned by next()), starting at 1 for the first node

close

public void close()
Description copied from interface: SequenceIterator
Close the iterator. This indicates to the supplier of the data that the client does not require any more items to be delivered by the iterator. This may enable the supplier to release resources. After calling close(), no further calls on the iterator should be made; if further calls are made, the effect of such calls is undefined.

(Currently, closing an iterator is important only when the data is being "pushed" in another thread. Closing the iterator terminates that thread and means that it needs to do no additional work. Indeed, failing to close the iterator may cause the push thread to hang waiting for the buffer to be emptied.)

Specified by:
close in interface SequenceIterator

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.