net.sf.saxon.om
Class SingletonIterator

java.lang.Object
  extended bynet.sf.saxon.om.SingletonIterator
All Implemented Interfaces:
AxisIterator, GroundedIterator, LastPositionFinder, ReversibleIterator, SequenceIterator

public class SingletonIterator
extends java.lang.Object
implements AxisIterator, ReversibleIterator, LastPositionFinder, GroundedIterator

SingletonIterator: an iterator over a sequence of zero or one values


Method Summary
 Item current()
          Get the current item in the sequence.
 SequenceIterator getAnother()
          Get another iterator over the same sequence of items, positioned at the start of the sequence.
 int getLastPosition()
          Get the last position (that is, the number of items in the sequence).
 SequenceIterator getReverseIterator()
          Get a new SequenceIterator that returns the same items in reverse order.
 Item getValue()
           
static AxisIterator makeIterator(Item item)
          Factory method.
 Value materialize()
          Return a SequenceExtent containing all the items in the sequence returned by this SequenceIterator
 Item next()
          Get the next item in the sequence.
 int position()
          Return the current position in the sequence.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

makeIterator

public static AxisIterator makeIterator(Item item)
Factory method.

Parameters:
item - the item to iterate over
Returns:
a SingletonIterator over the supplied item, or an EmptyIterator if the supplied item is null.

next

public Item next()
Description copied from interface: AxisIterator
Get the next item in the sequence.

Specified by:
next in interface AxisIterator
Returns:
the next Item. If there are no more nodes, return null.

current

public Item current()
Description copied from interface: AxisIterator
Get the current item in the sequence.

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

position

public int position()
Return the current position in the sequence.

Specified by:
position in interface AxisIterator
Returns:
0 before the first call on next(); 1 before the second call on next(); -1 after the second call on next().

getLastPosition

public int getLastPosition()
Description copied from interface: LastPositionFinder
Get the last position (that is, the number of items in the sequence). This method is non-destructive: it does not change the state of the iterator. The result is undefined if the next() method of the iterator has already returned null.

Specified by:
getLastPosition in interface LastPositionFinder

getAnother

public SequenceIterator getAnother()
Description copied from interface: AxisIterator
Get another iterator over the same sequence of items, positioned at the start of the sequence. It must be possible to call this method at any time, whether none, some, or all of the items in the original iterator have been read. The method is non-destructive: it does not change the state of the original iterator.

Specified by:
getAnother in interface AxisIterator
Returns:
a new iterator over the same sequence

getReverseIterator

public SequenceIterator getReverseIterator()
Description copied from interface: ReversibleIterator
Get a new SequenceIterator that returns the same items in reverse order. If this SequenceIterator is an AxisIterator, then the returned SequenceIterator must also be an AxisIterator.

Specified by:
getReverseIterator in interface ReversibleIterator

getValue

public Item getValue()

materialize

public Value materialize()
Return a SequenceExtent containing all the items in the sequence returned by this SequenceIterator

Specified by:
materialize in interface GroundedIterator
Returns:
the corresponding SequenceExtent if it exists, or null if it doesn't; in this case the caller must construct a new SequenceExtent by calling new SequenceExtent(iter.getAnother())