Package net.sf.saxon.om

Class SingletonIterator

java.lang.Object
net.sf.saxon.om.SingletonIterator
All Implemented Interfaces:
LastPositionFinder, ReversibleIterator, GroundedIterator, LookaheadIterator, SequenceIterator, UnfailingIterator
public class SingletonIterator extends Object implements UnfailingIterator, ReversibleIterator, LastPositionFinder, GroundedIterator, LookaheadIterator
SingletonIterator: an iterator over a sequence of zero or one values

  • Method Details

    • makeIterator

      public static UnfailingIterator 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.

    • 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

    • next

      public Item next()
      Description copied from interface: UnfailingIterator
      Get the next item in the sequence.
      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 Item current()
      Description copied from interface: UnfailingIterator
      Get the current item in the sequence.
      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 int position()
      Return the current position in the sequence.
      Specified by:
      position in interface SequenceIterator
      Specified by:
      position in interface UnfailingIterator
      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. This method must not be called unless the result of getProperties() on the iterator includes the bit setting SequenceIterator.LAST_POSITION_FINDER
      Specified by:
      getLastPosition in interface LastPositionFinder

    • 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

    • getAnother

      public SequenceIterator getAnother()
      Description copied from interface: UnfailingIterator
      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 SequenceIterator
      Specified by:
      getAnother in interface UnfailingIterator
      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
      Returns:
      an iterator over the items in reverse order

    • getValue

      public Item getValue()

    • materialize

      public GroundedValue materialize()
      Return a Value containing all the items in the sequence returned by this SequenceIterator
      Specified by:
      materialize in interface GroundedIterator
      Returns:
      the corresponding Value. If the value is a closure or a function call package, it will be evaluated and expanded.

    • 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 SequenceIterator.GROUNDED, SequenceIterator.LAST_POSITION_FINDER, and SequenceIterator.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.